Commit | Line | Data |
---|---|---|
bf0f6f24 IM |
1 | /* |
2 | * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH) | |
3 | * | |
4 | * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
5 | * | |
6 | * Interactivity improvements by Mike Galbraith | |
7 | * (C) 2007 Mike Galbraith <efault@gmx.de> | |
8 | * | |
9 | * Various enhancements by Dmitry Adamushko. | |
10 | * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com> | |
11 | * | |
12 | * Group scheduling enhancements by Srivatsa Vaddagiri | |
13 | * Copyright IBM Corporation, 2007 | |
14 | * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> | |
15 | * | |
16 | * Scaled math optimizations by Thomas Gleixner | |
17 | * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de> | |
21805085 PZ |
18 | * |
19 | * Adaptive scheduling granularity, math enhancements by Peter Zijlstra | |
20 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> | |
bf0f6f24 IM |
21 | */ |
22 | ||
9745512c | 23 | #include <linux/latencytop.h> |
1983a922 | 24 | #include <linux/sched.h> |
3436ae12 | 25 | #include <linux/cpumask.h> |
029632fb PZ |
26 | #include <linux/slab.h> |
27 | #include <linux/profile.h> | |
28 | #include <linux/interrupt.h> | |
cbee9f88 | 29 | #include <linux/mempolicy.h> |
e14808b4 | 30 | #include <linux/migrate.h> |
cbee9f88 | 31 | #include <linux/task_work.h> |
029632fb PZ |
32 | |
33 | #include <trace/events/sched.h> | |
34 | ||
35 | #include "sched.h" | |
9745512c | 36 | |
bf0f6f24 | 37 | /* |
21805085 | 38 | * Targeted preemption latency for CPU-bound tasks: |
864616ee | 39 | * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds) |
bf0f6f24 | 40 | * |
21805085 | 41 | * NOTE: this latency value is not the same as the concept of |
d274a4ce IM |
42 | * 'timeslice length' - timeslices in CFS are of variable length |
43 | * and have no persistent notion like in traditional, time-slice | |
44 | * based scheduling concepts. | |
bf0f6f24 | 45 | * |
d274a4ce IM |
46 | * (to see the precise effective timeslice length of your workload, |
47 | * run vmstat and monitor the context-switches (cs) field) | |
bf0f6f24 | 48 | */ |
21406928 MG |
49 | unsigned int sysctl_sched_latency = 6000000ULL; |
50 | unsigned int normalized_sysctl_sched_latency = 6000000ULL; | |
2bd8e6d4 | 51 | |
1983a922 CE |
52 | /* |
53 | * The initial- and re-scaling of tunables is configurable | |
54 | * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus)) | |
55 | * | |
56 | * Options are: | |
57 | * SCHED_TUNABLESCALING_NONE - unscaled, always *1 | |
58 | * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus) | |
59 | * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus | |
60 | */ | |
61 | enum sched_tunable_scaling sysctl_sched_tunable_scaling | |
62 | = SCHED_TUNABLESCALING_LOG; | |
63 | ||
2bd8e6d4 | 64 | /* |
b2be5e96 | 65 | * Minimal preemption granularity for CPU-bound tasks: |
864616ee | 66 | * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds) |
2bd8e6d4 | 67 | */ |
0bf377bb IM |
68 | unsigned int sysctl_sched_min_granularity = 750000ULL; |
69 | unsigned int normalized_sysctl_sched_min_granularity = 750000ULL; | |
21805085 PZ |
70 | |
71 | /* | |
b2be5e96 PZ |
72 | * is kept at sysctl_sched_latency / sysctl_sched_min_granularity |
73 | */ | |
0bf377bb | 74 | static unsigned int sched_nr_latency = 8; |
b2be5e96 PZ |
75 | |
76 | /* | |
2bba22c5 | 77 | * After fork, child runs first. If set to 0 (default) then |
b2be5e96 | 78 | * parent will (try to) run first. |
21805085 | 79 | */ |
2bba22c5 | 80 | unsigned int sysctl_sched_child_runs_first __read_mostly; |
bf0f6f24 | 81 | |
bf0f6f24 IM |
82 | /* |
83 | * SCHED_OTHER wake-up granularity. | |
172e082a | 84 | * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) |
bf0f6f24 IM |
85 | * |
86 | * This option delays the preemption effects of decoupled workloads | |
87 | * and reduces their over-scheduling. Synchronous workloads will still | |
88 | * have immediate wakeup/sleep latencies. | |
89 | */ | |
172e082a | 90 | unsigned int sysctl_sched_wakeup_granularity = 1000000UL; |
0bcdcf28 | 91 | unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL; |
bf0f6f24 | 92 | |
da84d961 IM |
93 | const_debug unsigned int sysctl_sched_migration_cost = 500000UL; |
94 | ||
a7a4f8a7 PT |
95 | /* |
96 | * The exponential sliding window over which load is averaged for shares | |
97 | * distribution. | |
98 | * (default: 10msec) | |
99 | */ | |
100 | unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; | |
101 | ||
ec12cb7f PT |
102 | #ifdef CONFIG_CFS_BANDWIDTH |
103 | /* | |
104 | * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool | |
105 | * each time a cfs_rq requests quota. | |
106 | * | |
107 | * Note: in the case that the slice exceeds the runtime remaining (either due | |
108 | * to consumption or the quota being specified to be smaller than the slice) | |
109 | * we will always only issue the remaining available time. | |
110 | * | |
111 | * default: 5 msec, units: microseconds | |
112 | */ | |
113 | unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; | |
114 | #endif | |
115 | ||
8527632d PG |
116 | static inline void update_load_add(struct load_weight *lw, unsigned long inc) |
117 | { | |
118 | lw->weight += inc; | |
119 | lw->inv_weight = 0; | |
120 | } | |
121 | ||
122 | static inline void update_load_sub(struct load_weight *lw, unsigned long dec) | |
123 | { | |
124 | lw->weight -= dec; | |
125 | lw->inv_weight = 0; | |
126 | } | |
127 | ||
128 | static inline void update_load_set(struct load_weight *lw, unsigned long w) | |
129 | { | |
130 | lw->weight = w; | |
131 | lw->inv_weight = 0; | |
132 | } | |
133 | ||
029632fb PZ |
134 | /* |
135 | * Increase the granularity value when there are more CPUs, | |
136 | * because with more CPUs the 'effective latency' as visible | |
137 | * to users decreases. But the relationship is not linear, | |
138 | * so pick a second-best guess by going with the log2 of the | |
139 | * number of CPUs. | |
140 | * | |
141 | * This idea comes from the SD scheduler of Con Kolivas: | |
142 | */ | |
143 | static int get_update_sysctl_factor(void) | |
144 | { | |
145 | unsigned int cpus = min_t(int, num_online_cpus(), 8); | |
146 | unsigned int factor; | |
147 | ||
148 | switch (sysctl_sched_tunable_scaling) { | |
149 | case SCHED_TUNABLESCALING_NONE: | |
150 | factor = 1; | |
151 | break; | |
152 | case SCHED_TUNABLESCALING_LINEAR: | |
153 | factor = cpus; | |
154 | break; | |
155 | case SCHED_TUNABLESCALING_LOG: | |
156 | default: | |
157 | factor = 1 + ilog2(cpus); | |
158 | break; | |
159 | } | |
160 | ||
161 | return factor; | |
162 | } | |
163 | ||
164 | static void update_sysctl(void) | |
165 | { | |
166 | unsigned int factor = get_update_sysctl_factor(); | |
167 | ||
168 | #define SET_SYSCTL(name) \ | |
169 | (sysctl_##name = (factor) * normalized_sysctl_##name) | |
170 | SET_SYSCTL(sched_min_granularity); | |
171 | SET_SYSCTL(sched_latency); | |
172 | SET_SYSCTL(sched_wakeup_granularity); | |
173 | #undef SET_SYSCTL | |
174 | } | |
175 | ||
176 | void sched_init_granularity(void) | |
177 | { | |
178 | update_sysctl(); | |
179 | } | |
180 | ||
9dbdb155 | 181 | #define WMULT_CONST (~0U) |
029632fb PZ |
182 | #define WMULT_SHIFT 32 |
183 | ||
9dbdb155 PZ |
184 | static void __update_inv_weight(struct load_weight *lw) |
185 | { | |
186 | unsigned long w; | |
187 | ||
188 | if (likely(lw->inv_weight)) | |
189 | return; | |
190 | ||
191 | w = scale_load_down(lw->weight); | |
192 | ||
193 | if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST)) | |
194 | lw->inv_weight = 1; | |
195 | else if (unlikely(!w)) | |
196 | lw->inv_weight = WMULT_CONST; | |
197 | else | |
198 | lw->inv_weight = WMULT_CONST / w; | |
199 | } | |
029632fb PZ |
200 | |
201 | /* | |
9dbdb155 PZ |
202 | * delta_exec * weight / lw.weight |
203 | * OR | |
204 | * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT | |
205 | * | |
206 | * Either weight := NICE_0_LOAD and lw \e prio_to_wmult[], in which case | |
207 | * we're guaranteed shift stays positive because inv_weight is guaranteed to | |
208 | * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22. | |
209 | * | |
210 | * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus | |
211 | * weight/lw.weight <= 1, and therefore our shift will also be positive. | |
029632fb | 212 | */ |
9dbdb155 | 213 | static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw) |
029632fb | 214 | { |
9dbdb155 PZ |
215 | u64 fact = scale_load_down(weight); |
216 | int shift = WMULT_SHIFT; | |
029632fb | 217 | |
9dbdb155 | 218 | __update_inv_weight(lw); |
029632fb | 219 | |
9dbdb155 PZ |
220 | if (unlikely(fact >> 32)) { |
221 | while (fact >> 32) { | |
222 | fact >>= 1; | |
223 | shift--; | |
224 | } | |
029632fb PZ |
225 | } |
226 | ||
9dbdb155 PZ |
227 | /* hint to use a 32x32->64 mul */ |
228 | fact = (u64)(u32)fact * lw->inv_weight; | |
029632fb | 229 | |
9dbdb155 PZ |
230 | while (fact >> 32) { |
231 | fact >>= 1; | |
232 | shift--; | |
233 | } | |
029632fb | 234 | |
9dbdb155 | 235 | return mul_u64_u32_shr(delta_exec, fact, shift); |
029632fb PZ |
236 | } |
237 | ||
238 | ||
239 | const struct sched_class fair_sched_class; | |
a4c2f00f | 240 | |
bf0f6f24 IM |
241 | /************************************************************** |
242 | * CFS operations on generic schedulable entities: | |
243 | */ | |
244 | ||
62160e3f | 245 | #ifdef CONFIG_FAIR_GROUP_SCHED |
bf0f6f24 | 246 | |
62160e3f | 247 | /* cpu runqueue to which this cfs_rq is attached */ |
bf0f6f24 IM |
248 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
249 | { | |
62160e3f | 250 | return cfs_rq->rq; |
bf0f6f24 IM |
251 | } |
252 | ||
62160e3f IM |
253 | /* An entity is a task if it doesn't "own" a runqueue */ |
254 | #define entity_is_task(se) (!se->my_q) | |
bf0f6f24 | 255 | |
8f48894f PZ |
256 | static inline struct task_struct *task_of(struct sched_entity *se) |
257 | { | |
258 | #ifdef CONFIG_SCHED_DEBUG | |
259 | WARN_ON_ONCE(!entity_is_task(se)); | |
260 | #endif | |
261 | return container_of(se, struct task_struct, se); | |
262 | } | |
263 | ||
b758149c PZ |
264 | /* Walk up scheduling entities hierarchy */ |
265 | #define for_each_sched_entity(se) \ | |
266 | for (; se; se = se->parent) | |
267 | ||
268 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) | |
269 | { | |
270 | return p->se.cfs_rq; | |
271 | } | |
272 | ||
273 | /* runqueue on which this entity is (to be) queued */ | |
274 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) | |
275 | { | |
276 | return se->cfs_rq; | |
277 | } | |
278 | ||
279 | /* runqueue "owned" by this group */ | |
280 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
281 | { | |
282 | return grp->my_q; | |
283 | } | |
284 | ||
aff3e498 PT |
285 | static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, |
286 | int force_update); | |
9ee474f5 | 287 | |
3d4b47b4 PZ |
288 | static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
289 | { | |
290 | if (!cfs_rq->on_list) { | |
67e86250 PT |
291 | /* |
292 | * Ensure we either appear before our parent (if already | |
293 | * enqueued) or force our parent to appear after us when it is | |
294 | * enqueued. The fact that we always enqueue bottom-up | |
295 | * reduces this to two cases. | |
296 | */ | |
297 | if (cfs_rq->tg->parent && | |
298 | cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) { | |
299 | list_add_rcu(&cfs_rq->leaf_cfs_rq_list, | |
300 | &rq_of(cfs_rq)->leaf_cfs_rq_list); | |
301 | } else { | |
302 | list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list, | |
3d4b47b4 | 303 | &rq_of(cfs_rq)->leaf_cfs_rq_list); |
67e86250 | 304 | } |
3d4b47b4 PZ |
305 | |
306 | cfs_rq->on_list = 1; | |
9ee474f5 | 307 | /* We should have no load, but we need to update last_decay. */ |
aff3e498 | 308 | update_cfs_rq_blocked_load(cfs_rq, 0); |
3d4b47b4 PZ |
309 | } |
310 | } | |
311 | ||
312 | static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) | |
313 | { | |
314 | if (cfs_rq->on_list) { | |
315 | list_del_rcu(&cfs_rq->leaf_cfs_rq_list); | |
316 | cfs_rq->on_list = 0; | |
317 | } | |
318 | } | |
319 | ||
b758149c PZ |
320 | /* Iterate thr' all leaf cfs_rq's on a runqueue */ |
321 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ | |
322 | list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) | |
323 | ||
324 | /* Do the two (enqueued) entities belong to the same group ? */ | |
fed14d45 | 325 | static inline struct cfs_rq * |
b758149c PZ |
326 | is_same_group(struct sched_entity *se, struct sched_entity *pse) |
327 | { | |
328 | if (se->cfs_rq == pse->cfs_rq) | |
fed14d45 | 329 | return se->cfs_rq; |
b758149c | 330 | |
fed14d45 | 331 | return NULL; |
b758149c PZ |
332 | } |
333 | ||
334 | static inline struct sched_entity *parent_entity(struct sched_entity *se) | |
335 | { | |
336 | return se->parent; | |
337 | } | |
338 | ||
464b7527 PZ |
339 | static void |
340 | find_matching_se(struct sched_entity **se, struct sched_entity **pse) | |
341 | { | |
342 | int se_depth, pse_depth; | |
343 | ||
344 | /* | |
345 | * preemption test can be made between sibling entities who are in the | |
346 | * same cfs_rq i.e who have a common parent. Walk up the hierarchy of | |
347 | * both tasks until we find their ancestors who are siblings of common | |
348 | * parent. | |
349 | */ | |
350 | ||
351 | /* First walk up until both entities are at same depth */ | |
fed14d45 PZ |
352 | se_depth = (*se)->depth; |
353 | pse_depth = (*pse)->depth; | |
464b7527 PZ |
354 | |
355 | while (se_depth > pse_depth) { | |
356 | se_depth--; | |
357 | *se = parent_entity(*se); | |
358 | } | |
359 | ||
360 | while (pse_depth > se_depth) { | |
361 | pse_depth--; | |
362 | *pse = parent_entity(*pse); | |
363 | } | |
364 | ||
365 | while (!is_same_group(*se, *pse)) { | |
366 | *se = parent_entity(*se); | |
367 | *pse = parent_entity(*pse); | |
368 | } | |
369 | } | |
370 | ||
8f48894f PZ |
371 | #else /* !CONFIG_FAIR_GROUP_SCHED */ |
372 | ||
373 | static inline struct task_struct *task_of(struct sched_entity *se) | |
374 | { | |
375 | return container_of(se, struct task_struct, se); | |
376 | } | |
bf0f6f24 | 377 | |
62160e3f IM |
378 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
379 | { | |
380 | return container_of(cfs_rq, struct rq, cfs); | |
bf0f6f24 IM |
381 | } |
382 | ||
383 | #define entity_is_task(se) 1 | |
384 | ||
b758149c PZ |
385 | #define for_each_sched_entity(se) \ |
386 | for (; se; se = NULL) | |
bf0f6f24 | 387 | |
b758149c | 388 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
bf0f6f24 | 389 | { |
b758149c | 390 | return &task_rq(p)->cfs; |
bf0f6f24 IM |
391 | } |
392 | ||
b758149c PZ |
393 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
394 | { | |
395 | struct task_struct *p = task_of(se); | |
396 | struct rq *rq = task_rq(p); | |
397 | ||
398 | return &rq->cfs; | |
399 | } | |
400 | ||
401 | /* runqueue "owned" by this group */ | |
402 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
403 | { | |
404 | return NULL; | |
405 | } | |
406 | ||
3d4b47b4 PZ |
407 | static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
408 | { | |
409 | } | |
410 | ||
411 | static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) | |
412 | { | |
413 | } | |
414 | ||
b758149c PZ |
415 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
416 | for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) | |
417 | ||
b758149c PZ |
418 | static inline struct sched_entity *parent_entity(struct sched_entity *se) |
419 | { | |
420 | return NULL; | |
421 | } | |
422 | ||
464b7527 PZ |
423 | static inline void |
424 | find_matching_se(struct sched_entity **se, struct sched_entity **pse) | |
425 | { | |
426 | } | |
427 | ||
b758149c PZ |
428 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
429 | ||
6c16a6dc | 430 | static __always_inline |
9dbdb155 | 431 | void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec); |
bf0f6f24 IM |
432 | |
433 | /************************************************************** | |
434 | * Scheduling class tree data structure manipulation methods: | |
435 | */ | |
436 | ||
1bf08230 | 437 | static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime) |
02e0431a | 438 | { |
1bf08230 | 439 | s64 delta = (s64)(vruntime - max_vruntime); |
368059a9 | 440 | if (delta > 0) |
1bf08230 | 441 | max_vruntime = vruntime; |
02e0431a | 442 | |
1bf08230 | 443 | return max_vruntime; |
02e0431a PZ |
444 | } |
445 | ||
0702e3eb | 446 | static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) |
b0ffd246 PZ |
447 | { |
448 | s64 delta = (s64)(vruntime - min_vruntime); | |
449 | if (delta < 0) | |
450 | min_vruntime = vruntime; | |
451 | ||
452 | return min_vruntime; | |
453 | } | |
454 | ||
54fdc581 FC |
455 | static inline int entity_before(struct sched_entity *a, |
456 | struct sched_entity *b) | |
457 | { | |
458 | return (s64)(a->vruntime - b->vruntime) < 0; | |
459 | } | |
460 | ||
1af5f730 PZ |
461 | static void update_min_vruntime(struct cfs_rq *cfs_rq) |
462 | { | |
463 | u64 vruntime = cfs_rq->min_vruntime; | |
464 | ||
465 | if (cfs_rq->curr) | |
466 | vruntime = cfs_rq->curr->vruntime; | |
467 | ||
468 | if (cfs_rq->rb_leftmost) { | |
469 | struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost, | |
470 | struct sched_entity, | |
471 | run_node); | |
472 | ||
e17036da | 473 | if (!cfs_rq->curr) |
1af5f730 PZ |
474 | vruntime = se->vruntime; |
475 | else | |
476 | vruntime = min_vruntime(vruntime, se->vruntime); | |
477 | } | |
478 | ||
1bf08230 | 479 | /* ensure we never gain time by being placed backwards. */ |
1af5f730 | 480 | cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); |
3fe1698b PZ |
481 | #ifndef CONFIG_64BIT |
482 | smp_wmb(); | |
483 | cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; | |
484 | #endif | |
1af5f730 PZ |
485 | } |
486 | ||
bf0f6f24 IM |
487 | /* |
488 | * Enqueue an entity into the rb-tree: | |
489 | */ | |
0702e3eb | 490 | static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 IM |
491 | { |
492 | struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; | |
493 | struct rb_node *parent = NULL; | |
494 | struct sched_entity *entry; | |
bf0f6f24 IM |
495 | int leftmost = 1; |
496 | ||
497 | /* | |
498 | * Find the right place in the rbtree: | |
499 | */ | |
500 | while (*link) { | |
501 | parent = *link; | |
502 | entry = rb_entry(parent, struct sched_entity, run_node); | |
503 | /* | |
504 | * We dont care about collisions. Nodes with | |
505 | * the same key stay together. | |
506 | */ | |
2bd2d6f2 | 507 | if (entity_before(se, entry)) { |
bf0f6f24 IM |
508 | link = &parent->rb_left; |
509 | } else { | |
510 | link = &parent->rb_right; | |
511 | leftmost = 0; | |
512 | } | |
513 | } | |
514 | ||
515 | /* | |
516 | * Maintain a cache of leftmost tree entries (it is frequently | |
517 | * used): | |
518 | */ | |
1af5f730 | 519 | if (leftmost) |
57cb499d | 520 | cfs_rq->rb_leftmost = &se->run_node; |
bf0f6f24 IM |
521 | |
522 | rb_link_node(&se->run_node, parent, link); | |
523 | rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline); | |
bf0f6f24 IM |
524 | } |
525 | ||
0702e3eb | 526 | static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 527 | { |
3fe69747 PZ |
528 | if (cfs_rq->rb_leftmost == &se->run_node) { |
529 | struct rb_node *next_node; | |
3fe69747 PZ |
530 | |
531 | next_node = rb_next(&se->run_node); | |
532 | cfs_rq->rb_leftmost = next_node; | |
3fe69747 | 533 | } |
e9acbff6 | 534 | |
bf0f6f24 | 535 | rb_erase(&se->run_node, &cfs_rq->tasks_timeline); |
bf0f6f24 IM |
536 | } |
537 | ||
029632fb | 538 | struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq) |
bf0f6f24 | 539 | { |
f4b6755f PZ |
540 | struct rb_node *left = cfs_rq->rb_leftmost; |
541 | ||
542 | if (!left) | |
543 | return NULL; | |
544 | ||
545 | return rb_entry(left, struct sched_entity, run_node); | |
bf0f6f24 IM |
546 | } |
547 | ||
ac53db59 RR |
548 | static struct sched_entity *__pick_next_entity(struct sched_entity *se) |
549 | { | |
550 | struct rb_node *next = rb_next(&se->run_node); | |
551 | ||
552 | if (!next) | |
553 | return NULL; | |
554 | ||
555 | return rb_entry(next, struct sched_entity, run_node); | |
556 | } | |
557 | ||
558 | #ifdef CONFIG_SCHED_DEBUG | |
029632fb | 559 | struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) |
aeb73b04 | 560 | { |
7eee3e67 | 561 | struct rb_node *last = rb_last(&cfs_rq->tasks_timeline); |
aeb73b04 | 562 | |
70eee74b BS |
563 | if (!last) |
564 | return NULL; | |
7eee3e67 IM |
565 | |
566 | return rb_entry(last, struct sched_entity, run_node); | |
aeb73b04 PZ |
567 | } |
568 | ||
bf0f6f24 IM |
569 | /************************************************************** |
570 | * Scheduling class statistics methods: | |
571 | */ | |
572 | ||
acb4a848 | 573 | int sched_proc_update_handler(struct ctl_table *table, int write, |
8d65af78 | 574 | void __user *buffer, size_t *lenp, |
b2be5e96 PZ |
575 | loff_t *ppos) |
576 | { | |
8d65af78 | 577 | int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
acb4a848 | 578 | int factor = get_update_sysctl_factor(); |
b2be5e96 PZ |
579 | |
580 | if (ret || !write) | |
581 | return ret; | |
582 | ||
583 | sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, | |
584 | sysctl_sched_min_granularity); | |
585 | ||
acb4a848 CE |
586 | #define WRT_SYSCTL(name) \ |
587 | (normalized_sysctl_##name = sysctl_##name / (factor)) | |
588 | WRT_SYSCTL(sched_min_granularity); | |
589 | WRT_SYSCTL(sched_latency); | |
590 | WRT_SYSCTL(sched_wakeup_granularity); | |
acb4a848 CE |
591 | #undef WRT_SYSCTL |
592 | ||
b2be5e96 PZ |
593 | return 0; |
594 | } | |
595 | #endif | |
647e7cac | 596 | |
a7be37ac | 597 | /* |
f9c0b095 | 598 | * delta /= w |
a7be37ac | 599 | */ |
9dbdb155 | 600 | static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se) |
a7be37ac | 601 | { |
f9c0b095 | 602 | if (unlikely(se->load.weight != NICE_0_LOAD)) |
9dbdb155 | 603 | delta = __calc_delta(delta, NICE_0_LOAD, &se->load); |
a7be37ac PZ |
604 | |
605 | return delta; | |
606 | } | |
607 | ||
647e7cac IM |
608 | /* |
609 | * The idea is to set a period in which each task runs once. | |
610 | * | |
532b1858 | 611 | * When there are too many tasks (sched_nr_latency) we have to stretch |
647e7cac IM |
612 | * this period because otherwise the slices get too small. |
613 | * | |
614 | * p = (nr <= nl) ? l : l*nr/nl | |
615 | */ | |
4d78e7b6 PZ |
616 | static u64 __sched_period(unsigned long nr_running) |
617 | { | |
618 | u64 period = sysctl_sched_latency; | |
b2be5e96 | 619 | unsigned long nr_latency = sched_nr_latency; |
4d78e7b6 PZ |
620 | |
621 | if (unlikely(nr_running > nr_latency)) { | |
4bf0b771 | 622 | period = sysctl_sched_min_granularity; |
4d78e7b6 | 623 | period *= nr_running; |
4d78e7b6 PZ |
624 | } |
625 | ||
626 | return period; | |
627 | } | |
628 | ||
647e7cac IM |
629 | /* |
630 | * We calculate the wall-time slice from the period by taking a part | |
631 | * proportional to the weight. | |
632 | * | |
f9c0b095 | 633 | * s = p*P[w/rw] |
647e7cac | 634 | */ |
6d0f0ebd | 635 | static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
21805085 | 636 | { |
0a582440 | 637 | u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq); |
f9c0b095 | 638 | |
0a582440 | 639 | for_each_sched_entity(se) { |
6272d68c | 640 | struct load_weight *load; |
3104bf03 | 641 | struct load_weight lw; |
6272d68c LM |
642 | |
643 | cfs_rq = cfs_rq_of(se); | |
644 | load = &cfs_rq->load; | |
f9c0b095 | 645 | |
0a582440 | 646 | if (unlikely(!se->on_rq)) { |
3104bf03 | 647 | lw = cfs_rq->load; |
0a582440 MG |
648 | |
649 | update_load_add(&lw, se->load.weight); | |
650 | load = &lw; | |
651 | } | |
9dbdb155 | 652 | slice = __calc_delta(slice, se->load.weight, load); |
0a582440 MG |
653 | } |
654 | return slice; | |
bf0f6f24 IM |
655 | } |
656 | ||
647e7cac | 657 | /* |
660cc00f | 658 | * We calculate the vruntime slice of a to-be-inserted task. |
647e7cac | 659 | * |
f9c0b095 | 660 | * vs = s/w |
647e7cac | 661 | */ |
f9c0b095 | 662 | static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
67e9fb2a | 663 | { |
f9c0b095 | 664 | return calc_delta_fair(sched_slice(cfs_rq, se), se); |
a7be37ac PZ |
665 | } |
666 | ||
a75cdaa9 | 667 | #ifdef CONFIG_SMP |
fb13c7ee MG |
668 | static unsigned long task_h_load(struct task_struct *p); |
669 | ||
a75cdaa9 AS |
670 | static inline void __update_task_entity_contrib(struct sched_entity *se); |
671 | ||
672 | /* Give new task start runnable values to heavy its load in infant time */ | |
673 | void init_task_runnable_average(struct task_struct *p) | |
674 | { | |
675 | u32 slice; | |
676 | ||
677 | p->se.avg.decay_count = 0; | |
678 | slice = sched_slice(task_cfs_rq(p), &p->se) >> 10; | |
679 | p->se.avg.runnable_avg_sum = slice; | |
680 | p->se.avg.runnable_avg_period = slice; | |
681 | __update_task_entity_contrib(&p->se); | |
682 | } | |
683 | #else | |
684 | void init_task_runnable_average(struct task_struct *p) | |
685 | { | |
686 | } | |
687 | #endif | |
688 | ||
bf0f6f24 | 689 | /* |
9dbdb155 | 690 | * Update the current task's runtime statistics. |
bf0f6f24 | 691 | */ |
b7cc0896 | 692 | static void update_curr(struct cfs_rq *cfs_rq) |
bf0f6f24 | 693 | { |
429d43bc | 694 | struct sched_entity *curr = cfs_rq->curr; |
78becc27 | 695 | u64 now = rq_clock_task(rq_of(cfs_rq)); |
9dbdb155 | 696 | u64 delta_exec; |
bf0f6f24 IM |
697 | |
698 | if (unlikely(!curr)) | |
699 | return; | |
700 | ||
9dbdb155 PZ |
701 | delta_exec = now - curr->exec_start; |
702 | if (unlikely((s64)delta_exec <= 0)) | |
34f28ecd | 703 | return; |
bf0f6f24 | 704 | |
8ebc91d9 | 705 | curr->exec_start = now; |
d842de87 | 706 | |
9dbdb155 PZ |
707 | schedstat_set(curr->statistics.exec_max, |
708 | max(delta_exec, curr->statistics.exec_max)); | |
709 | ||
710 | curr->sum_exec_runtime += delta_exec; | |
711 | schedstat_add(cfs_rq, exec_clock, delta_exec); | |
712 | ||
713 | curr->vruntime += calc_delta_fair(delta_exec, curr); | |
714 | update_min_vruntime(cfs_rq); | |
715 | ||
d842de87 SV |
716 | if (entity_is_task(curr)) { |
717 | struct task_struct *curtask = task_of(curr); | |
718 | ||
f977bb49 | 719 | trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); |
d842de87 | 720 | cpuacct_charge(curtask, delta_exec); |
f06febc9 | 721 | account_group_exec_runtime(curtask, delta_exec); |
d842de87 | 722 | } |
ec12cb7f PT |
723 | |
724 | account_cfs_rq_runtime(cfs_rq, delta_exec); | |
bf0f6f24 IM |
725 | } |
726 | ||
727 | static inline void | |
5870db5b | 728 | update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 729 | { |
78becc27 | 730 | schedstat_set(se->statistics.wait_start, rq_clock(rq_of(cfs_rq))); |
bf0f6f24 IM |
731 | } |
732 | ||
bf0f6f24 IM |
733 | /* |
734 | * Task is being enqueued - update stats: | |
735 | */ | |
d2417e5a | 736 | static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 737 | { |
bf0f6f24 IM |
738 | /* |
739 | * Are we enqueueing a waiting task? (for current tasks | |
740 | * a dequeue/enqueue event is a NOP) | |
741 | */ | |
429d43bc | 742 | if (se != cfs_rq->curr) |
5870db5b | 743 | update_stats_wait_start(cfs_rq, se); |
bf0f6f24 IM |
744 | } |
745 | ||
bf0f6f24 | 746 | static void |
9ef0a961 | 747 | update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 748 | { |
41acab88 | 749 | schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max, |
78becc27 | 750 | rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start)); |
41acab88 LDM |
751 | schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1); |
752 | schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum + | |
78becc27 | 753 | rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start); |
768d0c27 PZ |
754 | #ifdef CONFIG_SCHEDSTATS |
755 | if (entity_is_task(se)) { | |
756 | trace_sched_stat_wait(task_of(se), | |
78becc27 | 757 | rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start); |
768d0c27 PZ |
758 | } |
759 | #endif | |
41acab88 | 760 | schedstat_set(se->statistics.wait_start, 0); |
bf0f6f24 IM |
761 | } |
762 | ||
763 | static inline void | |
19b6a2e3 | 764 | update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 765 | { |
bf0f6f24 IM |
766 | /* |
767 | * Mark the end of the wait period if dequeueing a | |
768 | * waiting task: | |
769 | */ | |
429d43bc | 770 | if (se != cfs_rq->curr) |
9ef0a961 | 771 | update_stats_wait_end(cfs_rq, se); |
bf0f6f24 IM |
772 | } |
773 | ||
774 | /* | |
775 | * We are picking a new current task - update its stats: | |
776 | */ | |
777 | static inline void | |
79303e9e | 778 | update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 IM |
779 | { |
780 | /* | |
781 | * We are starting a new run period: | |
782 | */ | |
78becc27 | 783 | se->exec_start = rq_clock_task(rq_of(cfs_rq)); |
bf0f6f24 IM |
784 | } |
785 | ||
bf0f6f24 IM |
786 | /************************************************** |
787 | * Scheduling class queueing methods: | |
788 | */ | |
789 | ||
cbee9f88 PZ |
790 | #ifdef CONFIG_NUMA_BALANCING |
791 | /* | |
598f0ec0 MG |
792 | * Approximate time to scan a full NUMA task in ms. The task scan period is |
793 | * calculated based on the tasks virtual memory size and | |
794 | * numa_balancing_scan_size. | |
cbee9f88 | 795 | */ |
598f0ec0 MG |
796 | unsigned int sysctl_numa_balancing_scan_period_min = 1000; |
797 | unsigned int sysctl_numa_balancing_scan_period_max = 60000; | |
6e5fb223 PZ |
798 | |
799 | /* Portion of address space to scan in MB */ | |
800 | unsigned int sysctl_numa_balancing_scan_size = 256; | |
cbee9f88 | 801 | |
4b96a29b PZ |
802 | /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */ |
803 | unsigned int sysctl_numa_balancing_scan_delay = 1000; | |
804 | ||
598f0ec0 MG |
805 | static unsigned int task_nr_scan_windows(struct task_struct *p) |
806 | { | |
807 | unsigned long rss = 0; | |
808 | unsigned long nr_scan_pages; | |
809 | ||
810 | /* | |
811 | * Calculations based on RSS as non-present and empty pages are skipped | |
812 | * by the PTE scanner and NUMA hinting faults should be trapped based | |
813 | * on resident pages | |
814 | */ | |
815 | nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT); | |
816 | rss = get_mm_rss(p->mm); | |
817 | if (!rss) | |
818 | rss = nr_scan_pages; | |
819 | ||
820 | rss = round_up(rss, nr_scan_pages); | |
821 | return rss / nr_scan_pages; | |
822 | } | |
823 | ||
824 | /* For sanitys sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */ | |
825 | #define MAX_SCAN_WINDOW 2560 | |
826 | ||
827 | static unsigned int task_scan_min(struct task_struct *p) | |
828 | { | |
829 | unsigned int scan, floor; | |
830 | unsigned int windows = 1; | |
831 | ||
832 | if (sysctl_numa_balancing_scan_size < MAX_SCAN_WINDOW) | |
833 | windows = MAX_SCAN_WINDOW / sysctl_numa_balancing_scan_size; | |
834 | floor = 1000 / windows; | |
835 | ||
836 | scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p); | |
837 | return max_t(unsigned int, floor, scan); | |
838 | } | |
839 | ||
840 | static unsigned int task_scan_max(struct task_struct *p) | |
841 | { | |
842 | unsigned int smin = task_scan_min(p); | |
843 | unsigned int smax; | |
844 | ||
845 | /* Watch for min being lower than max due to floor calculations */ | |
846 | smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p); | |
847 | return max(smin, smax); | |
848 | } | |
849 | ||
0ec8aa00 PZ |
850 | static void account_numa_enqueue(struct rq *rq, struct task_struct *p) |
851 | { | |
852 | rq->nr_numa_running += (p->numa_preferred_nid != -1); | |
853 | rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p)); | |
854 | } | |
855 | ||
856 | static void account_numa_dequeue(struct rq *rq, struct task_struct *p) | |
857 | { | |
858 | rq->nr_numa_running -= (p->numa_preferred_nid != -1); | |
859 | rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p)); | |
860 | } | |
861 | ||
8c8a743c PZ |
862 | struct numa_group { |
863 | atomic_t refcount; | |
864 | ||
865 | spinlock_t lock; /* nr_tasks, tasks */ | |
866 | int nr_tasks; | |
e29cf08b | 867 | pid_t gid; |
8c8a743c PZ |
868 | struct list_head task_list; |
869 | ||
870 | struct rcu_head rcu; | |
20e07dea | 871 | nodemask_t active_nodes; |
989348b5 | 872 | unsigned long total_faults; |
7e2703e6 RR |
873 | /* |
874 | * Faults_cpu is used to decide whether memory should move | |
875 | * towards the CPU. As a consequence, these stats are weighted | |
876 | * more by CPU use than by memory faults. | |
877 | */ | |
50ec8a40 | 878 | unsigned long *faults_cpu; |
989348b5 | 879 | unsigned long faults[0]; |
8c8a743c PZ |
880 | }; |
881 | ||
be1e4e76 RR |
882 | /* Shared or private faults. */ |
883 | #define NR_NUMA_HINT_FAULT_TYPES 2 | |
884 | ||
885 | /* Memory and CPU locality */ | |
886 | #define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2) | |
887 | ||
888 | /* Averaged statistics, and temporary buffers. */ | |
889 | #define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2) | |
890 | ||
e29cf08b MG |
891 | pid_t task_numa_group_id(struct task_struct *p) |
892 | { | |
893 | return p->numa_group ? p->numa_group->gid : 0; | |
894 | } | |
895 | ||
ac8e895b MG |
896 | static inline int task_faults_idx(int nid, int priv) |
897 | { | |
be1e4e76 | 898 | return NR_NUMA_HINT_FAULT_TYPES * nid + priv; |
ac8e895b MG |
899 | } |
900 | ||
901 | static inline unsigned long task_faults(struct task_struct *p, int nid) | |
902 | { | |
ff1df896 | 903 | if (!p->numa_faults_memory) |
ac8e895b MG |
904 | return 0; |
905 | ||
ff1df896 RR |
906 | return p->numa_faults_memory[task_faults_idx(nid, 0)] + |
907 | p->numa_faults_memory[task_faults_idx(nid, 1)]; | |
ac8e895b MG |
908 | } |
909 | ||
83e1d2cd MG |
910 | static inline unsigned long group_faults(struct task_struct *p, int nid) |
911 | { | |
912 | if (!p->numa_group) | |
913 | return 0; | |
914 | ||
82897b4f WL |
915 | return p->numa_group->faults[task_faults_idx(nid, 0)] + |
916 | p->numa_group->faults[task_faults_idx(nid, 1)]; | |
83e1d2cd MG |
917 | } |
918 | ||
20e07dea RR |
919 | static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) |
920 | { | |
921 | return group->faults_cpu[task_faults_idx(nid, 0)] + | |
922 | group->faults_cpu[task_faults_idx(nid, 1)]; | |
923 | } | |
924 | ||
83e1d2cd MG |
925 | /* |
926 | * These return the fraction of accesses done by a particular task, or | |
927 | * task group, on a particular numa node. The group weight is given a | |
928 | * larger multiplier, in order to group tasks together that are almost | |
929 | * evenly spread out between numa nodes. | |
930 | */ | |
931 | static inline unsigned long task_weight(struct task_struct *p, int nid) | |
932 | { | |
933 | unsigned long total_faults; | |
934 | ||
ff1df896 | 935 | if (!p->numa_faults_memory) |
83e1d2cd MG |
936 | return 0; |
937 | ||
938 | total_faults = p->total_numa_faults; | |
939 | ||
940 | if (!total_faults) | |
941 | return 0; | |
942 | ||
943 | return 1000 * task_faults(p, nid) / total_faults; | |
944 | } | |
945 | ||
946 | static inline unsigned long group_weight(struct task_struct *p, int nid) | |
947 | { | |
989348b5 | 948 | if (!p->numa_group || !p->numa_group->total_faults) |
83e1d2cd MG |
949 | return 0; |
950 | ||
989348b5 | 951 | return 1000 * group_faults(p, nid) / p->numa_group->total_faults; |
83e1d2cd MG |
952 | } |
953 | ||
10f39042 RR |
954 | bool should_numa_migrate_memory(struct task_struct *p, struct page * page, |
955 | int src_nid, int dst_cpu) | |
956 | { | |
957 | struct numa_group *ng = p->numa_group; | |
958 | int dst_nid = cpu_to_node(dst_cpu); | |
959 | int last_cpupid, this_cpupid; | |
960 | ||
961 | this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid); | |
962 | ||
963 | /* | |
964 | * Multi-stage node selection is used in conjunction with a periodic | |
965 | * migration fault to build a temporal task<->page relation. By using | |
966 | * a two-stage filter we remove short/unlikely relations. | |
967 | * | |
968 | * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate | |
969 | * a task's usage of a particular page (n_p) per total usage of this | |
970 | * page (n_t) (in a given time-span) to a probability. | |
971 | * | |
972 | * Our periodic faults will sample this probability and getting the | |
973 | * same result twice in a row, given these samples are fully | |
974 | * independent, is then given by P(n)^2, provided our sample period | |
975 | * is sufficiently short compared to the usage pattern. | |
976 | * | |
977 | * This quadric squishes small probabilities, making it less likely we | |
978 | * act on an unlikely task<->page relation. | |
979 | */ | |
980 | last_cpupid = page_cpupid_xchg_last(page, this_cpupid); | |
981 | if (!cpupid_pid_unset(last_cpupid) && | |
982 | cpupid_to_nid(last_cpupid) != dst_nid) | |
983 | return false; | |
984 | ||
985 | /* Always allow migrate on private faults */ | |
986 | if (cpupid_match_pid(p, last_cpupid)) | |
987 | return true; | |
988 | ||
989 | /* A shared fault, but p->numa_group has not been set up yet. */ | |
990 | if (!ng) | |
991 | return true; | |
992 | ||
993 | /* | |
994 | * Do not migrate if the destination is not a node that | |
995 | * is actively used by this numa group. | |
996 | */ | |
997 | if (!node_isset(dst_nid, ng->active_nodes)) | |
998 | return false; | |
999 | ||
1000 | /* | |
1001 | * Source is a node that is not actively used by this | |
1002 | * numa group, while the destination is. Migrate. | |
1003 | */ | |
1004 | if (!node_isset(src_nid, ng->active_nodes)) | |
1005 | return true; | |
1006 | ||
1007 | /* | |
1008 | * Both source and destination are nodes in active | |
1009 | * use by this numa group. Maximize memory bandwidth | |
1010 | * by migrating from more heavily used groups, to less | |
1011 | * heavily used ones, spreading the load around. | |
1012 | * Use a 1/4 hysteresis to avoid spurious page movement. | |
1013 | */ | |
1014 | return group_faults(p, dst_nid) < (group_faults(p, src_nid) * 3 / 4); | |
1015 | } | |
1016 | ||
e6628d5b | 1017 | static unsigned long weighted_cpuload(const int cpu); |
58d081b5 MG |
1018 | static unsigned long source_load(int cpu, int type); |
1019 | static unsigned long target_load(int cpu, int type); | |
ced549fa | 1020 | static unsigned long capacity_of(int cpu); |
58d081b5 MG |
1021 | static long effective_load(struct task_group *tg, int cpu, long wl, long wg); |
1022 | ||
fb13c7ee | 1023 | /* Cached statistics for all CPUs within a node */ |
58d081b5 | 1024 | struct numa_stats { |
fb13c7ee | 1025 | unsigned long nr_running; |
58d081b5 | 1026 | unsigned long load; |
fb13c7ee MG |
1027 | |
1028 | /* Total compute capacity of CPUs on a node */ | |
5ef20ca1 | 1029 | unsigned long compute_capacity; |
fb13c7ee MG |
1030 | |
1031 | /* Approximate capacity in terms of runnable tasks on a node */ | |
5ef20ca1 | 1032 | unsigned long task_capacity; |
1b6a7495 | 1033 | int has_free_capacity; |
58d081b5 | 1034 | }; |
e6628d5b | 1035 | |
fb13c7ee MG |
1036 | /* |
1037 | * XXX borrowed from update_sg_lb_stats | |
1038 | */ | |
1039 | static void update_numa_stats(struct numa_stats *ns, int nid) | |
1040 | { | |
83d7f242 RR |
1041 | int smt, cpu, cpus = 0; |
1042 | unsigned long capacity; | |
fb13c7ee MG |
1043 | |
1044 | memset(ns, 0, sizeof(*ns)); | |
1045 | for_each_cpu(cpu, cpumask_of_node(nid)) { | |
1046 | struct rq *rq = cpu_rq(cpu); | |
1047 | ||
1048 | ns->nr_running += rq->nr_running; | |
1049 | ns->load += weighted_cpuload(cpu); | |
ced549fa | 1050 | ns->compute_capacity += capacity_of(cpu); |
5eca82a9 PZ |
1051 | |
1052 | cpus++; | |
fb13c7ee MG |
1053 | } |
1054 | ||
5eca82a9 PZ |
1055 | /* |
1056 | * If we raced with hotplug and there are no CPUs left in our mask | |
1057 | * the @ns structure is NULL'ed and task_numa_compare() will | |
1058 | * not find this node attractive. | |
1059 | * | |
1b6a7495 NP |
1060 | * We'll either bail at !has_free_capacity, or we'll detect a huge |
1061 | * imbalance and bail there. | |
5eca82a9 PZ |
1062 | */ |
1063 | if (!cpus) | |
1064 | return; | |
1065 | ||
83d7f242 RR |
1066 | /* smt := ceil(cpus / capacity), assumes: 1 < smt_power < 2 */ |
1067 | smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, ns->compute_capacity); | |
1068 | capacity = cpus / smt; /* cores */ | |
1069 | ||
1070 | ns->task_capacity = min_t(unsigned, capacity, | |
1071 | DIV_ROUND_CLOSEST(ns->compute_capacity, SCHED_CAPACITY_SCALE)); | |
1b6a7495 | 1072 | ns->has_free_capacity = (ns->nr_running < ns->task_capacity); |
fb13c7ee MG |
1073 | } |
1074 | ||
58d081b5 MG |
1075 | struct task_numa_env { |
1076 | struct task_struct *p; | |
e6628d5b | 1077 | |
58d081b5 MG |
1078 | int src_cpu, src_nid; |
1079 | int dst_cpu, dst_nid; | |
e6628d5b | 1080 | |
58d081b5 | 1081 | struct numa_stats src_stats, dst_stats; |
e6628d5b | 1082 | |
40ea2b42 | 1083 | int imbalance_pct; |
fb13c7ee MG |
1084 | |
1085 | struct task_struct *best_task; | |
1086 | long best_imp; | |
58d081b5 MG |
1087 | int best_cpu; |
1088 | }; | |
1089 | ||
fb13c7ee MG |
1090 | static void task_numa_assign(struct task_numa_env *env, |
1091 | struct task_struct *p, long imp) | |
1092 | { | |
1093 | if (env->best_task) | |
1094 | put_task_struct(env->best_task); | |
1095 | if (p) | |
1096 | get_task_struct(p); | |
1097 | ||
1098 | env->best_task = p; | |
1099 | env->best_imp = imp; | |
1100 | env->best_cpu = env->dst_cpu; | |
1101 | } | |
1102 | ||
28a21745 | 1103 | static bool load_too_imbalanced(long src_load, long dst_load, |
e63da036 RR |
1104 | struct task_numa_env *env) |
1105 | { | |
1106 | long imb, old_imb; | |
28a21745 RR |
1107 | long orig_src_load, orig_dst_load; |
1108 | long src_capacity, dst_capacity; | |
1109 | ||
1110 | /* | |
1111 | * The load is corrected for the CPU capacity available on each node. | |
1112 | * | |
1113 | * src_load dst_load | |
1114 | * ------------ vs --------- | |
1115 | * src_capacity dst_capacity | |
1116 | */ | |
1117 | src_capacity = env->src_stats.compute_capacity; | |
1118 | dst_capacity = env->dst_stats.compute_capacity; | |
e63da036 RR |
1119 | |
1120 | /* We care about the slope of the imbalance, not the direction. */ | |
1121 | if (dst_load < src_load) | |
1122 | swap(dst_load, src_load); | |
1123 | ||
1124 | /* Is the difference below the threshold? */ | |
28a21745 RR |
1125 | imb = dst_load * src_capacity * 100 - |
1126 | src_load * dst_capacity * env->imbalance_pct; | |
e63da036 RR |
1127 | if (imb <= 0) |
1128 | return false; | |
1129 | ||
1130 | /* | |
1131 | * The imbalance is above the allowed threshold. | |
1132 | * Compare it with the old imbalance. | |
1133 | */ | |
28a21745 RR |
1134 | orig_src_load = env->src_stats.load; |
1135 | orig_dst_load = env->dst_stats.load; | |
1136 | ||
e63da036 RR |
1137 | if (orig_dst_load < orig_src_load) |
1138 | swap(orig_dst_load, orig_src_load); | |
1139 | ||
28a21745 RR |
1140 | old_imb = orig_dst_load * src_capacity * 100 - |
1141 | orig_src_load * dst_capacity * env->imbalance_pct; | |
e63da036 RR |
1142 | |
1143 | /* Would this change make things worse? */ | |
1662867a | 1144 | return (imb > old_imb); |
e63da036 RR |
1145 | } |
1146 | ||
fb13c7ee MG |
1147 | /* |
1148 | * This checks if the overall compute and NUMA accesses of the system would | |
1149 | * be improved if the source tasks was migrated to the target dst_cpu taking | |
1150 | * into account that it might be best if task running on the dst_cpu should | |
1151 | * be exchanged with the source task | |
1152 | */ | |
887c290e RR |
1153 | static void task_numa_compare(struct task_numa_env *env, |
1154 | long taskimp, long groupimp) | |
fb13c7ee MG |
1155 | { |
1156 | struct rq *src_rq = cpu_rq(env->src_cpu); | |
1157 | struct rq *dst_rq = cpu_rq(env->dst_cpu); | |
1158 | struct task_struct *cur; | |
28a21745 | 1159 | long src_load, dst_load; |
fb13c7ee | 1160 | long load; |
1c5d3eb3 | 1161 | long imp = env->p->numa_group ? groupimp : taskimp; |
0132c3e1 | 1162 | long moveimp = imp; |
fb13c7ee MG |
1163 | |
1164 | rcu_read_lock(); | |
1165 | cur = ACCESS_ONCE(dst_rq->curr); | |
1166 | if (cur->pid == 0) /* idle */ | |
1167 | cur = NULL; | |
1168 | ||
1169 | /* | |
1170 | * "imp" is the fault differential for the source task between the | |
1171 | * source and destination node. Calculate the total differential for | |
1172 | * the source task and potential destination task. The more negative | |
1173 | * the value is, the more rmeote accesses that would be expected to | |
1174 | * be incurred if the tasks were swapped. | |
1175 | */ | |
1176 | if (cur) { | |
1177 | /* Skip this swap candidate if cannot move to the source cpu */ | |
1178 | if (!cpumask_test_cpu(env->src_cpu, tsk_cpus_allowed(cur))) | |
1179 | goto unlock; | |
1180 | ||
887c290e RR |
1181 | /* |
1182 | * If dst and source tasks are in the same NUMA group, or not | |
ca28aa53 | 1183 | * in any group then look only at task weights. |
887c290e | 1184 | */ |
ca28aa53 | 1185 | if (cur->numa_group == env->p->numa_group) { |
887c290e RR |
1186 | imp = taskimp + task_weight(cur, env->src_nid) - |
1187 | task_weight(cur, env->dst_nid); | |
ca28aa53 RR |
1188 | /* |
1189 | * Add some hysteresis to prevent swapping the | |
1190 | * tasks within a group over tiny differences. | |
1191 | */ | |
1192 | if (cur->numa_group) | |
1193 | imp -= imp/16; | |
887c290e | 1194 | } else { |
ca28aa53 RR |
1195 | /* |
1196 | * Compare the group weights. If a task is all by | |
1197 | * itself (not part of a group), use the task weight | |
1198 | * instead. | |
1199 | */ | |
ca28aa53 RR |
1200 | if (cur->numa_group) |
1201 | imp += group_weight(cur, env->src_nid) - | |
1202 | group_weight(cur, env->dst_nid); | |
1203 | else | |
1204 | imp += task_weight(cur, env->src_nid) - | |
1205 | task_weight(cur, env->dst_nid); | |
887c290e | 1206 | } |
fb13c7ee MG |
1207 | } |
1208 | ||
0132c3e1 | 1209 | if (imp <= env->best_imp && moveimp <= env->best_imp) |
fb13c7ee MG |
1210 | goto unlock; |
1211 | ||
1212 | if (!cur) { | |
1213 | /* Is there capacity at our destination? */ | |
b932c03c | 1214 | if (env->src_stats.nr_running <= env->src_stats.task_capacity && |
1b6a7495 | 1215 | !env->dst_stats.has_free_capacity) |
fb13c7ee MG |
1216 | goto unlock; |
1217 | ||
1218 | goto balance; | |
1219 | } | |
1220 | ||
1221 | /* Balance doesn't matter much if we're running a task per cpu */ | |
0132c3e1 RR |
1222 | if (imp > env->best_imp && src_rq->nr_running == 1 && |
1223 | dst_rq->nr_running == 1) | |
fb13c7ee MG |
1224 | goto assign; |
1225 | ||
1226 | /* | |
1227 | * In the overloaded case, try and keep the load balanced. | |
1228 | */ | |
1229 | balance: | |
e720fff6 PZ |
1230 | load = task_h_load(env->p); |
1231 | dst_load = env->dst_stats.load + load; | |
1232 | src_load = env->src_stats.load - load; | |
fb13c7ee | 1233 | |
0132c3e1 RR |
1234 | if (moveimp > imp && moveimp > env->best_imp) { |
1235 | /* | |
1236 | * If the improvement from just moving env->p direction is | |
1237 | * better than swapping tasks around, check if a move is | |
1238 | * possible. Store a slightly smaller score than moveimp, | |
1239 | * so an actually idle CPU will win. | |
1240 | */ | |
1241 | if (!load_too_imbalanced(src_load, dst_load, env)) { | |
1242 | imp = moveimp - 1; | |
1243 | cur = NULL; | |
1244 | goto assign; | |
1245 | } | |
1246 | } | |
1247 | ||
1248 | if (imp <= env->best_imp) | |
1249 | goto unlock; | |
1250 | ||
fb13c7ee | 1251 | if (cur) { |
e720fff6 PZ |
1252 | load = task_h_load(cur); |
1253 | dst_load -= load; | |
1254 | src_load += load; | |
fb13c7ee MG |
1255 | } |
1256 | ||
28a21745 | 1257 | if (load_too_imbalanced(src_load, dst_load, env)) |
fb13c7ee MG |
1258 | goto unlock; |
1259 | ||
1260 | assign: | |
1261 | task_numa_assign(env, cur, imp); | |
1262 | unlock: | |
1263 | rcu_read_unlock(); | |
1264 | } | |
1265 | ||
887c290e RR |
1266 | static void task_numa_find_cpu(struct task_numa_env *env, |
1267 | long taskimp, long groupimp) | |
2c8a50aa MG |
1268 | { |
1269 | int cpu; | |
1270 | ||
1271 | for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) { | |
1272 | /* Skip this CPU if the source task cannot migrate */ | |
1273 | if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p))) | |
1274 | continue; | |
1275 | ||
1276 | env->dst_cpu = cpu; | |
887c290e | 1277 | task_numa_compare(env, taskimp, groupimp); |
2c8a50aa MG |
1278 | } |
1279 | } | |
1280 | ||
58d081b5 MG |
1281 | static int task_numa_migrate(struct task_struct *p) |
1282 | { | |
58d081b5 MG |
1283 | struct task_numa_env env = { |
1284 | .p = p, | |
fb13c7ee | 1285 | |
58d081b5 | 1286 | .src_cpu = task_cpu(p), |
b32e86b4 | 1287 | .src_nid = task_node(p), |
fb13c7ee MG |
1288 | |
1289 | .imbalance_pct = 112, | |
1290 | ||
1291 | .best_task = NULL, | |
1292 | .best_imp = 0, | |
1293 | .best_cpu = -1 | |
58d081b5 MG |
1294 | }; |
1295 | struct sched_domain *sd; | |
887c290e | 1296 | unsigned long taskweight, groupweight; |
2c8a50aa | 1297 | int nid, ret; |
887c290e | 1298 | long taskimp, groupimp; |
e6628d5b | 1299 | |
58d081b5 | 1300 | /* |
fb13c7ee MG |
1301 | * Pick the lowest SD_NUMA domain, as that would have the smallest |
1302 | * imbalance and would be the first to start moving tasks about. | |
1303 | * | |
1304 | * And we want to avoid any moving of tasks about, as that would create | |
1305 | * random movement of tasks -- counter the numa conditions we're trying | |
1306 | * to satisfy here. | |
58d081b5 MG |
1307 | */ |
1308 | rcu_read_lock(); | |
fb13c7ee | 1309 | sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu)); |
46a73e8a RR |
1310 | if (sd) |
1311 | env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2; | |
e6628d5b MG |
1312 | rcu_read_unlock(); |
1313 | ||
46a73e8a RR |
1314 | /* |
1315 | * Cpusets can break the scheduler domain tree into smaller | |
1316 | * balance domains, some of which do not cross NUMA boundaries. | |
1317 | * Tasks that are "trapped" in such domains cannot be migrated | |
1318 | * elsewhere, so there is no point in (re)trying. | |
1319 | */ | |
1320 | if (unlikely(!sd)) { | |
de1b301a | 1321 | p->numa_preferred_nid = task_node(p); |
46a73e8a RR |
1322 | return -EINVAL; |
1323 | } | |
1324 | ||
887c290e RR |
1325 | taskweight = task_weight(p, env.src_nid); |
1326 | groupweight = group_weight(p, env.src_nid); | |
fb13c7ee | 1327 | update_numa_stats(&env.src_stats, env.src_nid); |
2c8a50aa | 1328 | env.dst_nid = p->numa_preferred_nid; |
887c290e RR |
1329 | taskimp = task_weight(p, env.dst_nid) - taskweight; |
1330 | groupimp = group_weight(p, env.dst_nid) - groupweight; | |
2c8a50aa | 1331 | update_numa_stats(&env.dst_stats, env.dst_nid); |
58d081b5 | 1332 | |
a43455a1 RR |
1333 | /* Try to find a spot on the preferred nid. */ |
1334 | task_numa_find_cpu(&env, taskimp, groupimp); | |
e1dda8a7 RR |
1335 | |
1336 | /* No space available on the preferred nid. Look elsewhere. */ | |
1337 | if (env.best_cpu == -1) { | |
2c8a50aa MG |
1338 | for_each_online_node(nid) { |
1339 | if (nid == env.src_nid || nid == p->numa_preferred_nid) | |
1340 | continue; | |
58d081b5 | 1341 | |
83e1d2cd | 1342 | /* Only consider nodes where both task and groups benefit */ |
887c290e RR |
1343 | taskimp = task_weight(p, nid) - taskweight; |
1344 | groupimp = group_weight(p, nid) - groupweight; | |
1345 | if (taskimp < 0 && groupimp < 0) | |
fb13c7ee MG |
1346 | continue; |
1347 | ||
2c8a50aa MG |
1348 | env.dst_nid = nid; |
1349 | update_numa_stats(&env.dst_stats, env.dst_nid); | |
887c290e | 1350 | task_numa_find_cpu(&env, taskimp, groupimp); |
58d081b5 MG |
1351 | } |
1352 | } | |
1353 | ||
68d1b02a RR |
1354 | /* |
1355 | * If the task is part of a workload that spans multiple NUMA nodes, | |
1356 | * and is migrating into one of the workload's active nodes, remember | |
1357 | * this node as the task's preferred numa node, so the workload can | |
1358 | * settle down. | |
1359 | * A task that migrated to a second choice node will be better off | |
1360 | * trying for a better one later. Do not set the preferred node here. | |
1361 | */ | |
db015dae RR |
1362 | if (p->numa_group) { |
1363 | if (env.best_cpu == -1) | |
1364 | nid = env.src_nid; | |
1365 | else | |
1366 | nid = env.dst_nid; | |
1367 | ||
1368 | if (node_isset(nid, p->numa_group->active_nodes)) | |
1369 | sched_setnuma(p, env.dst_nid); | |
1370 | } | |
1371 | ||
1372 | /* No better CPU than the current one was found. */ | |
1373 | if (env.best_cpu == -1) | |
1374 | return -EAGAIN; | |
0ec8aa00 | 1375 | |
04bb2f94 RR |
1376 | /* |
1377 | * Reset the scan period if the task is being rescheduled on an | |
1378 | * alternative node to recheck if the tasks is now properly placed. | |
1379 | */ | |
1380 | p->numa_scan_period = task_scan_min(p); | |
1381 | ||
fb13c7ee | 1382 | if (env.best_task == NULL) { |
286549dc MG |
1383 | ret = migrate_task_to(p, env.best_cpu); |
1384 | if (ret != 0) | |
1385 | trace_sched_stick_numa(p, env.src_cpu, env.best_cpu); | |
fb13c7ee MG |
1386 | return ret; |
1387 | } | |
1388 | ||
1389 | ret = migrate_swap(p, env.best_task); | |
286549dc MG |
1390 | if (ret != 0) |
1391 | trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task)); | |
fb13c7ee MG |
1392 | put_task_struct(env.best_task); |
1393 | return ret; | |
e6628d5b MG |
1394 | } |
1395 | ||
6b9a7460 MG |
1396 | /* Attempt to migrate a task to a CPU on the preferred node. */ |
1397 | static void numa_migrate_preferred(struct task_struct *p) | |
1398 | { | |
5085e2a3 RR |
1399 | unsigned long interval = HZ; |
1400 | ||
2739d3ee | 1401 | /* This task has no NUMA fault statistics yet */ |
ff1df896 | 1402 | if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults_memory)) |
6b9a7460 MG |
1403 | return; |
1404 | ||
2739d3ee | 1405 | /* Periodically retry migrating the task to the preferred node */ |
5085e2a3 RR |
1406 | interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16); |
1407 | p->numa_migrate_retry = jiffies + interval; | |
2739d3ee RR |
1408 | |
1409 | /* Success if task is already running on preferred CPU */ | |
de1b301a | 1410 | if (task_node(p) == p->numa_preferred_nid) |
6b9a7460 MG |
1411 | return; |
1412 | ||
1413 | /* Otherwise, try migrate to a CPU on the preferred node */ | |
2739d3ee | 1414 | task_numa_migrate(p); |
6b9a7460 MG |
1415 | } |
1416 | ||
20e07dea RR |
1417 | /* |
1418 | * Find the nodes on which the workload is actively running. We do this by | |
1419 | * tracking the nodes from which NUMA hinting faults are triggered. This can | |
1420 | * be different from the set of nodes where the workload's memory is currently | |
1421 | * located. | |
1422 | * | |
1423 | * The bitmask is used to make smarter decisions on when to do NUMA page | |
1424 | * migrations, To prevent flip-flopping, and excessive page migrations, nodes | |
1425 | * are added when they cause over 6/16 of the maximum number of faults, but | |
1426 | * only removed when they drop below 3/16. | |
1427 | */ | |
1428 | static void update_numa_active_node_mask(struct numa_group *numa_group) | |
1429 | { | |
1430 | unsigned long faults, max_faults = 0; | |
1431 | int nid; | |
1432 | ||
1433 | for_each_online_node(nid) { | |
1434 | faults = group_faults_cpu(numa_group, nid); | |
1435 | if (faults > max_faults) | |
1436 | max_faults = faults; | |
1437 | } | |
1438 | ||
1439 | for_each_online_node(nid) { | |
1440 | faults = group_faults_cpu(numa_group, nid); | |
1441 | if (!node_isset(nid, numa_group->active_nodes)) { | |
1442 | if (faults > max_faults * 6 / 16) | |
1443 | node_set(nid, numa_group->active_nodes); | |
1444 | } else if (faults < max_faults * 3 / 16) | |
1445 | node_clear(nid, numa_group->active_nodes); | |
1446 | } | |
1447 | } | |
1448 | ||
04bb2f94 RR |
1449 | /* |
1450 | * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS | |
1451 | * increments. The more local the fault statistics are, the higher the scan | |
a22b4b01 RR |
1452 | * period will be for the next scan window. If local/(local+remote) ratio is |
1453 | * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS) | |
1454 | * the scan period will decrease. Aim for 70% local accesses. | |
04bb2f94 RR |
1455 | */ |
1456 | #define NUMA_PERIOD_SLOTS 10 | |
a22b4b01 | 1457 | #define NUMA_PERIOD_THRESHOLD 7 |
04bb2f94 RR |
1458 | |
1459 | /* | |
1460 | * Increase the scan period (slow down scanning) if the majority of | |
1461 | * our memory is already on our local node, or if the majority of | |
1462 | * the page accesses are shared with other processes. | |
1463 | * Otherwise, decrease the scan period. | |
1464 | */ | |
1465 | static void update_task_scan_period(struct task_struct *p, | |
1466 | unsigned long shared, unsigned long private) | |
1467 | { | |
1468 | unsigned int period_slot; | |
1469 | int ratio; | |
1470 | int diff; | |
1471 | ||
1472 | unsigned long remote = p->numa_faults_locality[0]; | |
1473 | unsigned long local = p->numa_faults_locality[1]; | |
1474 | ||
1475 | /* | |
1476 | * If there were no record hinting faults then either the task is | |
1477 | * completely idle or all activity is areas that are not of interest | |
1478 | * to automatic numa balancing. Scan slower | |
1479 | */ | |
1480 | if (local + shared == 0) { | |
1481 | p->numa_scan_period = min(p->numa_scan_period_max, | |
1482 | p->numa_scan_period << 1); | |
1483 | ||
1484 | p->mm->numa_next_scan = jiffies + | |
1485 | msecs_to_jiffies(p->numa_scan_period); | |
1486 | ||
1487 | return; | |
1488 | } | |
1489 | ||
1490 | /* | |
1491 | * Prepare to scale scan period relative to the current period. | |
1492 | * == NUMA_PERIOD_THRESHOLD scan period stays the same | |
1493 | * < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster) | |
1494 | * >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower) | |
1495 | */ | |
1496 | period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS); | |
1497 | ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote); | |
1498 | if (ratio >= NUMA_PERIOD_THRESHOLD) { | |
1499 | int slot = ratio - NUMA_PERIOD_THRESHOLD; | |
1500 | if (!slot) | |
1501 | slot = 1; | |
1502 | diff = slot * period_slot; | |
1503 | } else { | |
1504 | diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot; | |
1505 | ||
1506 | /* | |
1507 | * Scale scan rate increases based on sharing. There is an | |
1508 | * inverse relationship between the degree of sharing and | |
1509 | * the adjustment made to the scanning period. Broadly | |
1510 | * speaking the intent is that there is little point | |
1511 | * scanning faster if shared accesses dominate as it may | |
1512 | * simply bounce migrations uselessly | |
1513 | */ | |
04bb2f94 RR |
1514 | ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared)); |
1515 | diff = (diff * ratio) / NUMA_PERIOD_SLOTS; | |
1516 | } | |
1517 | ||
1518 | p->numa_scan_period = clamp(p->numa_scan_period + diff, | |
1519 | task_scan_min(p), task_scan_max(p)); | |
1520 | memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); | |
1521 | } | |
1522 | ||
7e2703e6 RR |
1523 | /* |
1524 | * Get the fraction of time the task has been running since the last | |
1525 | * NUMA placement cycle. The scheduler keeps similar statistics, but | |
1526 | * decays those on a 32ms period, which is orders of magnitude off | |
1527 | * from the dozens-of-seconds NUMA balancing period. Use the scheduler | |
1528 | * stats only if the task is so new there are no NUMA statistics yet. | |
1529 | */ | |
1530 | static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period) | |
1531 | { | |
1532 | u64 runtime, delta, now; | |
1533 | /* Use the start of this time slice to avoid calculations. */ | |
1534 | now = p->se.exec_start; | |
1535 | runtime = p->se.sum_exec_runtime; | |
1536 | ||
1537 | if (p->last_task_numa_placement) { | |
1538 | delta = runtime - p->last_sum_exec_runtime; | |
1539 | *period = now - p->last_task_numa_placement; | |
1540 | } else { | |
1541 | delta = p->se.avg.runnable_avg_sum; | |
1542 | *period = p->se.avg.runnable_avg_period; | |
1543 | } | |
1544 | ||
1545 | p->last_sum_exec_runtime = runtime; | |
1546 | p->last_task_numa_placement = now; | |
1547 | ||
1548 | return delta; | |
1549 | } | |
1550 | ||
cbee9f88 PZ |
1551 | static void task_numa_placement(struct task_struct *p) |
1552 | { | |
83e1d2cd MG |
1553 | int seq, nid, max_nid = -1, max_group_nid = -1; |
1554 | unsigned long max_faults = 0, max_group_faults = 0; | |
04bb2f94 | 1555 | unsigned long fault_types[2] = { 0, 0 }; |
7e2703e6 RR |
1556 | unsigned long total_faults; |
1557 | u64 runtime, period; | |
7dbd13ed | 1558 | spinlock_t *group_lock = NULL; |
cbee9f88 | 1559 | |
2832bc19 | 1560 | seq = ACCESS_ONCE(p->mm->numa_scan_seq); |
cbee9f88 PZ |
1561 | if (p->numa_scan_seq == seq) |
1562 | return; | |
1563 | p->numa_scan_seq = seq; | |
598f0ec0 | 1564 | p->numa_scan_period_max = task_scan_max(p); |
cbee9f88 | 1565 | |
7e2703e6 RR |
1566 | total_faults = p->numa_faults_locality[0] + |
1567 | p->numa_faults_locality[1]; | |
1568 | runtime = numa_get_avg_runtime(p, &period); | |
1569 | ||
7dbd13ed MG |
1570 | /* If the task is part of a group prevent parallel updates to group stats */ |
1571 | if (p->numa_group) { | |
1572 | group_lock = &p->numa_group->lock; | |
60e69eed | 1573 | spin_lock_irq(group_lock); |
7dbd13ed MG |
1574 | } |
1575 | ||
688b7585 MG |
1576 | /* Find the node with the highest number of faults */ |
1577 | for_each_online_node(nid) { | |
83e1d2cd | 1578 | unsigned long faults = 0, group_faults = 0; |
ac8e895b | 1579 | int priv, i; |
745d6147 | 1580 | |
be1e4e76 | 1581 | for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) { |
7e2703e6 | 1582 | long diff, f_diff, f_weight; |
8c8a743c | 1583 | |
ac8e895b | 1584 | i = task_faults_idx(nid, priv); |
745d6147 | 1585 | |
ac8e895b | 1586 | /* Decay existing window, copy faults since last scan */ |
35664fd4 | 1587 | diff = p->numa_faults_buffer_memory[i] - p->numa_faults_memory[i] / 2; |
ff1df896 RR |
1588 | fault_types[priv] += p->numa_faults_buffer_memory[i]; |
1589 | p->numa_faults_buffer_memory[i] = 0; | |
fb13c7ee | 1590 | |
7e2703e6 RR |
1591 | /* |
1592 | * Normalize the faults_from, so all tasks in a group | |
1593 | * count according to CPU use, instead of by the raw | |
1594 | * number of faults. Tasks with little runtime have | |
1595 | * little over-all impact on throughput, and thus their | |
1596 | * faults are less important. | |
1597 | */ | |
1598 | f_weight = div64_u64(runtime << 16, period + 1); | |
1599 | f_weight = (f_weight * p->numa_faults_buffer_cpu[i]) / | |
1600 | (total_faults + 1); | |
35664fd4 | 1601 | f_diff = f_weight - p->numa_faults_cpu[i] / 2; |
50ec8a40 RR |
1602 | p->numa_faults_buffer_cpu[i] = 0; |
1603 | ||
35664fd4 RR |
1604 | p->numa_faults_memory[i] += diff; |
1605 | p->numa_faults_cpu[i] += f_diff; | |
ff1df896 | 1606 | faults += p->numa_faults_memory[i]; |
83e1d2cd | 1607 | p->total_numa_faults += diff; |
8c8a743c PZ |
1608 | if (p->numa_group) { |
1609 | /* safe because we can only change our own group */ | |
989348b5 | 1610 | p->numa_group->faults[i] += diff; |
50ec8a40 | 1611 | p->numa_group->faults_cpu[i] += f_diff; |
989348b5 MG |
1612 | p->numa_group->total_faults += diff; |
1613 | group_faults += p->numa_group->faults[i]; | |
8c8a743c | 1614 | } |
ac8e895b MG |
1615 | } |
1616 | ||
688b7585 MG |
1617 | if (faults > max_faults) { |
1618 | max_faults = faults; | |
1619 | max_nid = nid; | |
1620 | } | |
83e1d2cd MG |
1621 | |
1622 | if (group_faults > max_group_faults) { | |
1623 | max_group_faults = group_faults; | |
1624 | max_group_nid = nid; | |
1625 | } | |
1626 | } | |
1627 | ||
04bb2f94 RR |
1628 | update_task_scan_period(p, fault_types[0], fault_types[1]); |
1629 | ||
7dbd13ed | 1630 | if (p->numa_group) { |
20e07dea | 1631 | update_numa_active_node_mask(p->numa_group); |
60e69eed | 1632 | spin_unlock_irq(group_lock); |
f0b8a4af | 1633 | max_nid = max_group_nid; |
688b7585 MG |
1634 | } |
1635 | ||
bb97fc31 RR |
1636 | if (max_faults) { |
1637 | /* Set the new preferred node */ | |
1638 | if (max_nid != p->numa_preferred_nid) | |
1639 | sched_setnuma(p, max_nid); | |
1640 | ||
1641 | if (task_node(p) != p->numa_preferred_nid) | |
1642 | numa_migrate_preferred(p); | |
3a7053b3 | 1643 | } |
cbee9f88 PZ |
1644 | } |
1645 | ||
8c8a743c PZ |
1646 | static inline int get_numa_group(struct numa_group *grp) |
1647 | { | |
1648 | return atomic_inc_not_zero(&grp->refcount); | |
1649 | } | |
1650 | ||
1651 | static inline void put_numa_group(struct numa_group *grp) | |
1652 | { | |
1653 | if (atomic_dec_and_test(&grp->refcount)) | |
1654 | kfree_rcu(grp, rcu); | |
1655 | } | |
1656 | ||
3e6a9418 MG |
1657 | static void task_numa_group(struct task_struct *p, int cpupid, int flags, |
1658 | int *priv) | |
8c8a743c PZ |
1659 | { |
1660 | struct numa_group *grp, *my_grp; | |
1661 | struct task_struct *tsk; | |
1662 | bool join = false; | |
1663 | int cpu = cpupid_to_cpu(cpupid); | |
1664 | int i; | |
1665 | ||
1666 | if (unlikely(!p->numa_group)) { | |
1667 | unsigned int size = sizeof(struct numa_group) + | |
50ec8a40 | 1668 | 4*nr_node_ids*sizeof(unsigned long); |
8c8a743c PZ |
1669 | |
1670 | grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); | |
1671 | if (!grp) | |
1672 | return; | |
1673 | ||
1674 | atomic_set(&grp->refcount, 1); | |
1675 | spin_lock_init(&grp->lock); | |
1676 | INIT_LIST_HEAD(&grp->task_list); | |
e29cf08b | 1677 | grp->gid = p->pid; |
50ec8a40 | 1678 | /* Second half of the array tracks nids where faults happen */ |
be1e4e76 RR |
1679 | grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES * |
1680 | nr_node_ids; | |
8c8a743c | 1681 | |
20e07dea RR |
1682 | node_set(task_node(current), grp->active_nodes); |
1683 | ||
be1e4e76 | 1684 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
ff1df896 | 1685 | grp->faults[i] = p->numa_faults_memory[i]; |
8c8a743c | 1686 | |
989348b5 | 1687 | grp->total_faults = p->total_numa_faults; |
83e1d2cd | 1688 | |
8c8a743c PZ |
1689 | list_add(&p->numa_entry, &grp->task_list); |
1690 | grp->nr_tasks++; | |
1691 | rcu_assign_pointer(p->numa_group, grp); | |
1692 | } | |
1693 | ||
1694 | rcu_read_lock(); | |
1695 | tsk = ACCESS_ONCE(cpu_rq(cpu)->curr); | |
1696 | ||
1697 | if (!cpupid_match_pid(tsk, cpupid)) | |
3354781a | 1698 | goto no_join; |
8c8a743c PZ |
1699 | |
1700 | grp = rcu_dereference(tsk->numa_group); | |
1701 | if (!grp) | |
3354781a | 1702 | goto no_join; |
8c8a743c PZ |
1703 | |
1704 | my_grp = p->numa_group; | |
1705 | if (grp == my_grp) | |
3354781a | 1706 | goto no_join; |
8c8a743c PZ |
1707 | |
1708 | /* | |
1709 | * Only join the other group if its bigger; if we're the bigger group, | |
1710 | * the other task will join us. | |
1711 | */ | |
1712 | if (my_grp->nr_tasks > grp->nr_tasks) | |
3354781a | 1713 | goto no_join; |
8c8a743c PZ |
1714 | |
1715 | /* | |
1716 | * Tie-break on the grp address. | |
1717 | */ | |
1718 | if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp) | |
3354781a | 1719 | goto no_join; |
8c8a743c | 1720 | |
dabe1d99 RR |
1721 | /* Always join threads in the same process. */ |
1722 | if (tsk->mm == current->mm) | |
1723 | join = true; | |
1724 | ||
1725 | /* Simple filter to avoid false positives due to PID collisions */ | |
1726 | if (flags & TNF_SHARED) | |
1727 | join = true; | |
8c8a743c | 1728 | |
3e6a9418 MG |
1729 | /* Update priv based on whether false sharing was detected */ |
1730 | *priv = !join; | |
1731 | ||
dabe1d99 | 1732 | if (join && !get_numa_group(grp)) |
3354781a | 1733 | goto no_join; |
8c8a743c | 1734 | |
8c8a743c PZ |
1735 | rcu_read_unlock(); |
1736 | ||
1737 | if (!join) | |
1738 | return; | |
1739 | ||
60e69eed MG |
1740 | BUG_ON(irqs_disabled()); |
1741 | double_lock_irq(&my_grp->lock, &grp->lock); | |
989348b5 | 1742 | |
be1e4e76 | 1743 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) { |
ff1df896 RR |
1744 | my_grp->faults[i] -= p->numa_faults_memory[i]; |
1745 | grp->faults[i] += p->numa_faults_memory[i]; | |
8c8a743c | 1746 | } |
989348b5 MG |
1747 | my_grp->total_faults -= p->total_numa_faults; |
1748 | grp->total_faults += p->total_numa_faults; | |
8c8a743c PZ |
1749 | |
1750 | list_move(&p->numa_entry, &grp->task_list); | |
1751 | my_grp->nr_tasks--; | |
1752 | grp->nr_tasks++; | |
1753 | ||
1754 | spin_unlock(&my_grp->lock); | |
60e69eed | 1755 | spin_unlock_irq(&grp->lock); |
8c8a743c PZ |
1756 | |
1757 | rcu_assign_pointer(p->numa_group, grp); | |
1758 | ||
1759 | put_numa_group(my_grp); | |
3354781a PZ |
1760 | return; |
1761 | ||
1762 | no_join: | |
1763 | rcu_read_unlock(); | |
1764 | return; | |
8c8a743c PZ |
1765 | } |
1766 | ||
1767 | void task_numa_free(struct task_struct *p) | |
1768 | { | |
1769 | struct numa_group *grp = p->numa_group; | |
ff1df896 | 1770 | void *numa_faults = p->numa_faults_memory; |
e9dd685c SR |
1771 | unsigned long flags; |
1772 | int i; | |
8c8a743c PZ |
1773 | |
1774 | if (grp) { | |
e9dd685c | 1775 | spin_lock_irqsave(&grp->lock, flags); |
be1e4e76 | 1776 | for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
ff1df896 | 1777 | grp->faults[i] -= p->numa_faults_memory[i]; |
989348b5 | 1778 | grp->total_faults -= p->total_numa_faults; |
83e1d2cd | 1779 | |
8c8a743c PZ |
1780 | list_del(&p->numa_entry); |
1781 | grp->nr_tasks--; | |
e9dd685c | 1782 | spin_unlock_irqrestore(&grp->lock, flags); |
8c8a743c PZ |
1783 | rcu_assign_pointer(p->numa_group, NULL); |
1784 | put_numa_group(grp); | |
1785 | } | |
1786 | ||
ff1df896 RR |
1787 | p->numa_faults_memory = NULL; |
1788 | p->numa_faults_buffer_memory = NULL; | |
50ec8a40 RR |
1789 | p->numa_faults_cpu= NULL; |
1790 | p->numa_faults_buffer_cpu = NULL; | |
82727018 | 1791 | kfree(numa_faults); |
8c8a743c PZ |
1792 | } |
1793 | ||
cbee9f88 PZ |
1794 | /* |
1795 | * Got a PROT_NONE fault for a page on @node. | |
1796 | */ | |
58b46da3 | 1797 | void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) |
cbee9f88 PZ |
1798 | { |
1799 | struct task_struct *p = current; | |
6688cc05 | 1800 | bool migrated = flags & TNF_MIGRATED; |
58b46da3 | 1801 | int cpu_node = task_node(current); |
792568ec | 1802 | int local = !!(flags & TNF_FAULT_LOCAL); |
ac8e895b | 1803 | int priv; |
cbee9f88 | 1804 | |
10e84b97 | 1805 | if (!numabalancing_enabled) |
1a687c2e MG |
1806 | return; |
1807 | ||
9ff1d9ff MG |
1808 | /* for example, ksmd faulting in a user's mm */ |
1809 | if (!p->mm) | |
1810 | return; | |
1811 | ||
82727018 RR |
1812 | /* Do not worry about placement if exiting */ |
1813 | if (p->state == TASK_DEAD) | |
1814 | return; | |
1815 | ||
f809ca9a | 1816 | /* Allocate buffer to track faults on a per-node basis */ |
ff1df896 | 1817 | if (unlikely(!p->numa_faults_memory)) { |
be1e4e76 RR |
1818 | int size = sizeof(*p->numa_faults_memory) * |
1819 | NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids; | |
f809ca9a | 1820 | |
be1e4e76 | 1821 | p->numa_faults_memory = kzalloc(size, GFP_KERNEL|__GFP_NOWARN); |
ff1df896 | 1822 | if (!p->numa_faults_memory) |
f809ca9a | 1823 | return; |
745d6147 | 1824 | |
ff1df896 | 1825 | BUG_ON(p->numa_faults_buffer_memory); |
be1e4e76 RR |
1826 | /* |
1827 | * The averaged statistics, shared & private, memory & cpu, | |
1828 | * occupy the first half of the array. The second half of the | |
1829 | * array is for current counters, which are averaged into the | |
1830 | * first set by task_numa_placement. | |
1831 | */ | |
50ec8a40 RR |
1832 | p->numa_faults_cpu = p->numa_faults_memory + (2 * nr_node_ids); |
1833 | p->numa_faults_buffer_memory = p->numa_faults_memory + (4 * nr_node_ids); | |
1834 | p->numa_faults_buffer_cpu = p->numa_faults_memory + (6 * nr_node_ids); | |
83e1d2cd | 1835 | p->total_numa_faults = 0; |
04bb2f94 | 1836 | memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); |
f809ca9a | 1837 | } |
cbee9f88 | 1838 | |
8c8a743c PZ |
1839 | /* |
1840 | * First accesses are treated as private, otherwise consider accesses | |
1841 | * to be private if the accessing pid has not changed | |
1842 | */ | |
1843 | if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) { | |
1844 | priv = 1; | |
1845 | } else { | |
1846 | priv = cpupid_match_pid(p, last_cpupid); | |
6688cc05 | 1847 | if (!priv && !(flags & TNF_NO_GROUP)) |
3e6a9418 | 1848 | task_numa_group(p, last_cpupid, flags, &priv); |
8c8a743c PZ |
1849 | } |
1850 | ||
792568ec RR |
1851 | /* |
1852 | * If a workload spans multiple NUMA nodes, a shared fault that | |
1853 | * occurs wholly within the set of nodes that the workload is | |
1854 | * actively using should be counted as local. This allows the | |
1855 | * scan rate to slow down when a workload has settled down. | |
1856 | */ | |
1857 | if (!priv && !local && p->numa_group && | |
1858 | node_isset(cpu_node, p->numa_group->active_nodes) && | |
1859 | node_isset(mem_node, p->numa_group->active_nodes)) | |
1860 | local = 1; | |
1861 | ||
cbee9f88 | 1862 | task_numa_placement(p); |
f809ca9a | 1863 | |
2739d3ee RR |
1864 | /* |
1865 | * Retry task to preferred node migration periodically, in case it | |
1866 | * case it previously failed, or the scheduler moved us. | |
1867 | */ | |
1868 | if (time_after(jiffies, p->numa_migrate_retry)) | |
6b9a7460 MG |
1869 | numa_migrate_preferred(p); |
1870 | ||
b32e86b4 IM |
1871 | if (migrated) |
1872 | p->numa_pages_migrated += pages; | |
1873 | ||
58b46da3 RR |
1874 | p->numa_faults_buffer_memory[task_faults_idx(mem_node, priv)] += pages; |
1875 | p->numa_faults_buffer_cpu[task_faults_idx(cpu_node, priv)] += pages; | |
792568ec | 1876 | p->numa_faults_locality[local] += pages; |
cbee9f88 PZ |
1877 | } |
1878 | ||
6e5fb223 PZ |
1879 | static void reset_ptenuma_scan(struct task_struct *p) |
1880 | { | |
1881 | ACCESS_ONCE(p->mm->numa_scan_seq)++; | |
1882 | p->mm->numa_scan_offset = 0; | |
1883 | } | |
1884 | ||
cbee9f88 PZ |
1885 | /* |
1886 | * The expensive part of numa migration is done from task_work context. | |
1887 | * Triggered from task_tick_numa(). | |
1888 | */ | |
1889 | void task_numa_work(struct callback_head *work) | |
1890 | { | |
1891 | unsigned long migrate, next_scan, now = jiffies; | |
1892 | struct task_struct *p = current; | |
1893 | struct mm_struct *mm = p->mm; | |
6e5fb223 | 1894 | struct vm_area_struct *vma; |
9f40604c | 1895 | unsigned long start, end; |
598f0ec0 | 1896 | unsigned long nr_pte_updates = 0; |
9f40604c | 1897 | long pages; |
cbee9f88 PZ |
1898 | |
1899 | WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work)); | |
1900 | ||
1901 | work->next = work; /* protect against double add */ | |
1902 | /* | |
1903 | * Who cares about NUMA placement when they're dying. | |
1904 | * | |
1905 | * NOTE: make sure not to dereference p->mm before this check, | |
1906 | * exit_task_work() happens _after_ exit_mm() so we could be called | |
1907 | * without p->mm even though we still had it when we enqueued this | |
1908 | * work. | |
1909 | */ | |
1910 | if (p->flags & PF_EXITING) | |
1911 | return; | |
1912 | ||
930aa174 | 1913 | if (!mm->numa_next_scan) { |
7e8d16b6 MG |
1914 | mm->numa_next_scan = now + |
1915 | msecs_to_jiffies(sysctl_numa_balancing_scan_delay); | |
b8593bfd MG |
1916 | } |
1917 | ||
cbee9f88 PZ |
1918 | /* |
1919 | * Enforce maximal scan/migration frequency.. | |
1920 | */ | |
1921 | migrate = mm->numa_next_scan; | |
1922 | if (time_before(now, migrate)) | |
1923 | return; | |
1924 | ||
598f0ec0 MG |
1925 | if (p->numa_scan_period == 0) { |
1926 | p->numa_scan_period_max = task_scan_max(p); | |
1927 | p->numa_scan_period = task_scan_min(p); | |
1928 | } | |
cbee9f88 | 1929 | |
fb003b80 | 1930 | next_scan = now + msecs_to_jiffies(p->numa_scan_period); |
cbee9f88 PZ |
1931 | if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate) |
1932 | return; | |
1933 | ||
19a78d11 PZ |
1934 | /* |
1935 | * Delay this task enough that another task of this mm will likely win | |
1936 | * the next time around. | |
1937 | */ | |
1938 | p->node_stamp += 2 * TICK_NSEC; | |
1939 | ||
9f40604c MG |
1940 | start = mm->numa_scan_offset; |
1941 | pages = sysctl_numa_balancing_scan_size; | |
1942 | pages <<= 20 - PAGE_SHIFT; /* MB in pages */ | |
1943 | if (!pages) | |
1944 | return; | |
cbee9f88 | 1945 | |
6e5fb223 | 1946 | down_read(&mm->mmap_sem); |
9f40604c | 1947 | vma = find_vma(mm, start); |
6e5fb223 PZ |
1948 | if (!vma) { |
1949 | reset_ptenuma_scan(p); | |
9f40604c | 1950 | start = 0; |
6e5fb223 PZ |
1951 | vma = mm->mmap; |
1952 | } | |
9f40604c | 1953 | for (; vma; vma = vma->vm_next) { |
fc314724 | 1954 | if (!vma_migratable(vma) || !vma_policy_mof(p, vma)) |
6e5fb223 PZ |
1955 | continue; |
1956 | ||
4591ce4f MG |
1957 | /* |
1958 | * Shared library pages mapped by multiple processes are not | |
1959 | * migrated as it is expected they are cache replicated. Avoid | |
1960 | * hinting faults in read-only file-backed mappings or the vdso | |
1961 | * as migrating the pages will be of marginal benefit. | |
1962 | */ | |
1963 | if (!vma->vm_mm || | |
1964 | (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) | |
1965 | continue; | |
1966 | ||
3c67f474 MG |
1967 | /* |
1968 | * Skip inaccessible VMAs to avoid any confusion between | |
1969 | * PROT_NONE and NUMA hinting ptes | |
1970 | */ | |
1971 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) | |
1972 | continue; | |
4591ce4f | 1973 | |
9f40604c MG |
1974 | do { |
1975 | start = max(start, vma->vm_start); | |
1976 | end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE); | |
1977 | end = min(end, vma->vm_end); | |
598f0ec0 MG |
1978 | nr_pte_updates += change_prot_numa(vma, start, end); |
1979 | ||
1980 | /* | |
1981 | * Scan sysctl_numa_balancing_scan_size but ensure that | |
1982 | * at least one PTE is updated so that unused virtual | |
1983 | * address space is quickly skipped. | |
1984 | */ | |
1985 | if (nr_pte_updates) | |
1986 | pages -= (end - start) >> PAGE_SHIFT; | |
6e5fb223 | 1987 | |
9f40604c MG |
1988 | start = end; |
1989 | if (pages <= 0) | |
1990 | goto out; | |
3cf1962c RR |
1991 | |
1992 | cond_resched(); | |
9f40604c | 1993 | } while (end != vma->vm_end); |
cbee9f88 | 1994 | } |
6e5fb223 | 1995 | |
9f40604c | 1996 | out: |
6e5fb223 | 1997 | /* |
c69307d5 PZ |
1998 | * It is possible to reach the end of the VMA list but the last few |
1999 | * VMAs are not guaranteed to the vma_migratable. If they are not, we | |
2000 | * would find the !migratable VMA on the next scan but not reset the | |
2001 | * scanner to the start so check it now. | |
6e5fb223 PZ |
2002 | */ |
2003 | if (vma) | |
9f40604c | 2004 | mm->numa_scan_offset = start; |
6e5fb223 PZ |
2005 | else |
2006 | reset_ptenuma_scan(p); | |
2007 | up_read(&mm->mmap_sem); | |
cbee9f88 PZ |
2008 | } |
2009 | ||
2010 | /* | |
2011 | * Drive the periodic memory faults.. | |
2012 | */ | |
2013 | void task_tick_numa(struct rq *rq, struct task_struct *curr) | |
2014 | { | |
2015 | struct callback_head *work = &curr->numa_work; | |
2016 | u64 period, now; | |
2017 | ||
2018 | /* | |
2019 | * We don't care about NUMA placement if we don't have memory. | |
2020 | */ | |
2021 | if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work) | |
2022 | return; | |
2023 | ||
2024 | /* | |
2025 | * Using runtime rather than walltime has the dual advantage that | |
2026 | * we (mostly) drive the selection from busy threads and that the | |
2027 | * task needs to have done some actual work before we bother with | |
2028 | * NUMA placement. | |
2029 | */ | |
2030 | now = curr->se.sum_exec_runtime; | |
2031 | period = (u64)curr->numa_scan_period * NSEC_PER_MSEC; | |
2032 | ||
2033 | if (now - curr->node_stamp > period) { | |
4b96a29b | 2034 | if (!curr->node_stamp) |
598f0ec0 | 2035 | curr->numa_scan_period = task_scan_min(curr); |
19a78d11 | 2036 | curr->node_stamp += period; |
cbee9f88 PZ |
2037 | |
2038 | if (!time_before(jiffies, curr->mm->numa_next_scan)) { | |
2039 | init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */ | |
2040 | task_work_add(curr, work, true); | |
2041 | } | |
2042 | } | |
2043 | } | |
2044 | #else | |
2045 | static void task_tick_numa(struct rq *rq, struct task_struct *curr) | |
2046 | { | |
2047 | } | |
0ec8aa00 PZ |
2048 | |
2049 | static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p) | |
2050 | { | |
2051 | } | |
2052 | ||
2053 | static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p) | |
2054 | { | |
2055 | } | |
cbee9f88 PZ |
2056 | #endif /* CONFIG_NUMA_BALANCING */ |
2057 | ||
30cfdcfc DA |
2058 | static void |
2059 | account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2060 | { | |
2061 | update_load_add(&cfs_rq->load, se->load.weight); | |
c09595f6 | 2062 | if (!parent_entity(se)) |
029632fb | 2063 | update_load_add(&rq_of(cfs_rq)->load, se->load.weight); |
367456c7 | 2064 | #ifdef CONFIG_SMP |
0ec8aa00 PZ |
2065 | if (entity_is_task(se)) { |
2066 | struct rq *rq = rq_of(cfs_rq); | |
2067 | ||
2068 | account_numa_enqueue(rq, task_of(se)); | |
2069 | list_add(&se->group_node, &rq->cfs_tasks); | |
2070 | } | |
367456c7 | 2071 | #endif |
30cfdcfc | 2072 | cfs_rq->nr_running++; |
30cfdcfc DA |
2073 | } |
2074 | ||
2075 | static void | |
2076 | account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
2077 | { | |
2078 | update_load_sub(&cfs_rq->load, se->load.weight); | |
c09595f6 | 2079 | if (!parent_entity(se)) |
029632fb | 2080 | update_load_sub(&rq_of(cfs_rq)->load, se->load.weight); |
0ec8aa00 PZ |
2081 | if (entity_is_task(se)) { |
2082 | account_numa_dequeue(rq_of(cfs_rq), task_of(se)); | |
b87f1724 | 2083 | list_del_init(&se->group_node); |
0ec8aa00 | 2084 | } |
30cfdcfc | 2085 | cfs_rq->nr_running--; |
30cfdcfc DA |
2086 | } |
2087 | ||
3ff6dcac YZ |
2088 | #ifdef CONFIG_FAIR_GROUP_SCHED |
2089 | # ifdef CONFIG_SMP | |
cf5f0acf PZ |
2090 | static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq) |
2091 | { | |
2092 | long tg_weight; | |
2093 | ||
2094 | /* | |
2095 | * Use this CPU's actual weight instead of the last load_contribution | |
2096 | * to gain a more accurate current total weight. See | |
2097 | * update_cfs_rq_load_contribution(). | |
2098 | */ | |
bf5b986e | 2099 | tg_weight = atomic_long_read(&tg->load_avg); |
82958366 | 2100 | tg_weight -= cfs_rq->tg_load_contrib; |
cf5f0acf PZ |
2101 | tg_weight += cfs_rq->load.weight; |
2102 | ||
2103 | return tg_weight; | |
2104 | } | |
2105 | ||
6d5ab293 | 2106 | static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
3ff6dcac | 2107 | { |
cf5f0acf | 2108 | long tg_weight, load, shares; |
3ff6dcac | 2109 | |
cf5f0acf | 2110 | tg_weight = calc_tg_weight(tg, cfs_rq); |
6d5ab293 | 2111 | load = cfs_rq->load.weight; |
3ff6dcac | 2112 | |
3ff6dcac | 2113 | shares = (tg->shares * load); |
cf5f0acf PZ |
2114 | if (tg_weight) |
2115 | shares /= tg_weight; | |
3ff6dcac YZ |
2116 | |
2117 | if (shares < MIN_SHARES) | |
2118 | shares = MIN_SHARES; | |
2119 | if (shares > tg->shares) | |
2120 | shares = tg->shares; | |
2121 | ||
2122 | return shares; | |
2123 | } | |
3ff6dcac | 2124 | # else /* CONFIG_SMP */ |
6d5ab293 | 2125 | static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
3ff6dcac YZ |
2126 | { |
2127 | return tg->shares; | |
2128 | } | |
3ff6dcac | 2129 | # endif /* CONFIG_SMP */ |
2069dd75 PZ |
2130 | static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, |
2131 | unsigned long weight) | |
2132 | { | |
19e5eebb PT |
2133 | if (se->on_rq) { |
2134 | /* commit outstanding execution time */ | |
2135 | if (cfs_rq->curr == se) | |
2136 | update_curr(cfs_rq); | |
2069dd75 | 2137 | account_entity_dequeue(cfs_rq, se); |
19e5eebb | 2138 | } |
2069dd75 PZ |
2139 | |
2140 | update_load_set(&se->load, weight); | |
2141 | ||
2142 | if (se->on_rq) | |
2143 | account_entity_enqueue(cfs_rq, se); | |
2144 | } | |
2145 | ||
82958366 PT |
2146 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); |
2147 | ||
6d5ab293 | 2148 | static void update_cfs_shares(struct cfs_rq *cfs_rq) |
2069dd75 PZ |
2149 | { |
2150 | struct task_group *tg; | |
2151 | struct sched_entity *se; | |
3ff6dcac | 2152 | long shares; |
2069dd75 | 2153 | |
2069dd75 PZ |
2154 | tg = cfs_rq->tg; |
2155 | se = tg->se[cpu_of(rq_of(cfs_rq))]; | |
64660c86 | 2156 | if (!se || throttled_hierarchy(cfs_rq)) |
2069dd75 | 2157 | return; |
3ff6dcac YZ |
2158 | #ifndef CONFIG_SMP |
2159 | if (likely(se->load.weight == tg->shares)) | |
2160 | return; | |
2161 | #endif | |
6d5ab293 | 2162 | shares = calc_cfs_shares(cfs_rq, tg); |
2069dd75 PZ |
2163 | |
2164 | reweight_entity(cfs_rq_of(se), se, shares); | |
2165 | } | |
2166 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
6d5ab293 | 2167 | static inline void update_cfs_shares(struct cfs_rq *cfs_rq) |
2069dd75 PZ |
2168 | { |
2169 | } | |
2170 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
2171 | ||
141965c7 | 2172 | #ifdef CONFIG_SMP |
5b51f2f8 PT |
2173 | /* |
2174 | * We choose a half-life close to 1 scheduling period. | |
2175 | * Note: The tables below are dependent on this value. | |
2176 | */ | |
2177 | #define LOAD_AVG_PERIOD 32 | |
2178 | #define LOAD_AVG_MAX 47742 /* maximum possible load avg */ | |
2179 | #define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */ | |
2180 | ||
2181 | /* Precomputed fixed inverse multiplies for multiplication by y^n */ | |
2182 | static const u32 runnable_avg_yN_inv[] = { | |
2183 | 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6, | |
2184 | 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85, | |
2185 | 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581, | |
2186 | 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9, | |
2187 | 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80, | |
2188 | 0x85aac367, 0x82cd8698, | |
2189 | }; | |
2190 | ||
2191 | /* | |
2192 | * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent | |
2193 | * over-estimates when re-combining. | |
2194 | */ | |
2195 | static const u32 runnable_avg_yN_sum[] = { | |
2196 | 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103, | |
2197 | 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082, | |
2198 | 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371, | |
2199 | }; | |
2200 | ||
9d85f21c PT |
2201 | /* |
2202 | * Approximate: | |
2203 | * val * y^n, where y^32 ~= 0.5 (~1 scheduling period) | |
2204 | */ | |
2205 | static __always_inline u64 decay_load(u64 val, u64 n) | |
2206 | { | |
5b51f2f8 PT |
2207 | unsigned int local_n; |
2208 | ||
2209 | if (!n) | |
2210 | return val; | |
2211 | else if (unlikely(n > LOAD_AVG_PERIOD * 63)) | |
2212 | return 0; | |
2213 | ||
2214 | /* after bounds checking we can collapse to 32-bit */ | |
2215 | local_n = n; | |
2216 | ||
2217 | /* | |
2218 | * As y^PERIOD = 1/2, we can combine | |
2219 | * y^n = 1/2^(n/PERIOD) * k^(n%PERIOD) | |
2220 | * With a look-up table which covers k^n (n<PERIOD) | |
2221 | * | |
2222 | * To achieve constant time decay_load. | |
2223 | */ | |
2224 | if (unlikely(local_n >= LOAD_AVG_PERIOD)) { | |
2225 | val >>= local_n / LOAD_AVG_PERIOD; | |
2226 | local_n %= LOAD_AVG_PERIOD; | |
9d85f21c PT |
2227 | } |
2228 | ||
5b51f2f8 PT |
2229 | val *= runnable_avg_yN_inv[local_n]; |
2230 | /* We don't use SRR here since we always want to round down. */ | |
2231 | return val >> 32; | |
2232 | } | |
2233 | ||
2234 | /* | |
2235 | * For updates fully spanning n periods, the contribution to runnable | |
2236 | * average will be: \Sum 1024*y^n | |
2237 | * | |
2238 | * We can compute this reasonably efficiently by combining: | |
2239 | * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD} | |
2240 | */ | |
2241 | static u32 __compute_runnable_contrib(u64 n) | |
2242 | { | |
2243 | u32 contrib = 0; | |
2244 | ||
2245 | if (likely(n <= LOAD_AVG_PERIOD)) | |
2246 | return runnable_avg_yN_sum[n]; | |
2247 | else if (unlikely(n >= LOAD_AVG_MAX_N)) | |
2248 | return LOAD_AVG_MAX; | |
2249 | ||
2250 | /* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */ | |
2251 | do { | |
2252 | contrib /= 2; /* y^LOAD_AVG_PERIOD = 1/2 */ | |
2253 | contrib += runnable_avg_yN_sum[LOAD_AVG_PERIOD]; | |
2254 | ||
2255 | n -= LOAD_AVG_PERIOD; | |
2256 | } while (n > LOAD_AVG_PERIOD); | |
2257 | ||
2258 | contrib = decay_load(contrib, n); | |
2259 | return contrib + runnable_avg_yN_sum[n]; | |
9d85f21c PT |
2260 | } |
2261 | ||
2262 | /* | |
2263 | * We can represent the historical contribution to runnable average as the | |
2264 | * coefficients of a geometric series. To do this we sub-divide our runnable | |
2265 | * history into segments of approximately 1ms (1024us); label the segment that | |
2266 | * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g. | |
2267 | * | |
2268 | * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ... | |
2269 | * p0 p1 p2 | |
2270 | * (now) (~1ms ago) (~2ms ago) | |
2271 | * | |
2272 | * Let u_i denote the fraction of p_i that the entity was runnable. | |
2273 | * | |
2274 | * We then designate the fractions u_i as our co-efficients, yielding the | |
2275 | * following representation of historical load: | |
2276 | * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ... | |
2277 | * | |
2278 | * We choose y based on the with of a reasonably scheduling period, fixing: | |
2279 | * y^32 = 0.5 | |
2280 | * | |
2281 | * This means that the contribution to load ~32ms ago (u_32) will be weighted | |
2282 | * approximately half as much as the contribution to load within the last ms | |
2283 | * (u_0). | |
2284 | * | |
2285 | * When a period "rolls over" and we have new u_0`, multiplying the previous | |
2286 | * sum again by y is sufficient to update: | |
2287 | * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... ) | |
2288 | * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}] | |
2289 | */ | |
2290 | static __always_inline int __update_entity_runnable_avg(u64 now, | |
2291 | struct sched_avg *sa, | |
2292 | int runnable) | |
2293 | { | |
5b51f2f8 PT |
2294 | u64 delta, periods; |
2295 | u32 runnable_contrib; | |
9d85f21c PT |
2296 | int delta_w, decayed = 0; |
2297 | ||
2298 | delta = now - sa->last_runnable_update; | |
2299 | /* | |
2300 | * This should only happen when time goes backwards, which it | |
2301 | * unfortunately does during sched clock init when we swap over to TSC. | |
2302 | */ | |
2303 | if ((s64)delta < 0) { | |
2304 | sa->last_runnable_update = now; | |
2305 | return 0; | |
2306 | } | |
2307 | ||
2308 | /* | |
2309 | * Use 1024ns as the unit of measurement since it's a reasonable | |
2310 | * approximation of 1us and fast to compute. | |
2311 | */ | |
2312 | delta >>= 10; | |
2313 | if (!delta) | |
2314 | return 0; | |
2315 | sa->last_runnable_update = now; | |
2316 | ||
2317 | /* delta_w is the amount already accumulated against our next period */ | |
2318 | delta_w = sa->runnable_avg_period % 1024; | |
2319 | if (delta + delta_w >= 1024) { | |
2320 | /* period roll-over */ | |
2321 | decayed = 1; | |
2322 | ||
2323 | /* | |
2324 | * Now that we know we're crossing a period boundary, figure | |
2325 | * out how much from delta we need to complete the current | |
2326 | * period and accrue it. | |
2327 | */ | |
2328 | delta_w = 1024 - delta_w; | |
5b51f2f8 PT |
2329 | if (runnable) |
2330 | sa->runnable_avg_sum += delta_w; | |
2331 | sa->runnable_avg_period += delta_w; | |
2332 | ||
2333 | delta -= delta_w; | |
2334 | ||
2335 | /* Figure out how many additional periods this update spans */ | |
2336 | periods = delta / 1024; | |
2337 | delta %= 1024; | |
2338 | ||
2339 | sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum, | |
2340 | periods + 1); | |
2341 | sa->runnable_avg_period = decay_load(sa->runnable_avg_period, | |
2342 | periods + 1); | |
2343 | ||
2344 | /* Efficiently calculate \sum (1..n_period) 1024*y^i */ | |
2345 | runnable_contrib = __compute_runnable_contrib(periods); | |
2346 | if (runnable) | |
2347 | sa->runnable_avg_sum += runnable_contrib; | |
2348 | sa->runnable_avg_period += runnable_contrib; | |
9d85f21c PT |
2349 | } |
2350 | ||
2351 | /* Remainder of delta accrued against u_0` */ | |
2352 | if (runnable) | |
2353 | sa->runnable_avg_sum += delta; | |
2354 | sa->runnable_avg_period += delta; | |
2355 | ||
2356 | return decayed; | |
2357 | } | |
2358 | ||
9ee474f5 | 2359 | /* Synchronize an entity's decay with its parenting cfs_rq.*/ |
aff3e498 | 2360 | static inline u64 __synchronize_entity_decay(struct sched_entity *se) |
9ee474f5 PT |
2361 | { |
2362 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
2363 | u64 decays = atomic64_read(&cfs_rq->decay_counter); | |
2364 | ||
2365 | decays -= se->avg.decay_count; | |
2366 | if (!decays) | |
aff3e498 | 2367 | return 0; |
9ee474f5 PT |
2368 | |
2369 | se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays); | |
2370 | se->avg.decay_count = 0; | |
aff3e498 PT |
2371 | |
2372 | return decays; | |
9ee474f5 PT |
2373 | } |
2374 | ||
c566e8e9 PT |
2375 | #ifdef CONFIG_FAIR_GROUP_SCHED |
2376 | static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, | |
2377 | int force_update) | |
2378 | { | |
2379 | struct task_group *tg = cfs_rq->tg; | |
bf5b986e | 2380 | long tg_contrib; |
c566e8e9 PT |
2381 | |
2382 | tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg; | |
2383 | tg_contrib -= cfs_rq->tg_load_contrib; | |
2384 | ||
bf5b986e AS |
2385 | if (force_update || abs(tg_contrib) > cfs_rq->tg_load_contrib / 8) { |
2386 | atomic_long_add(tg_contrib, &tg->load_avg); | |
c566e8e9 PT |
2387 | cfs_rq->tg_load_contrib += tg_contrib; |
2388 | } | |
2389 | } | |
8165e145 | 2390 | |
bb17f655 PT |
2391 | /* |
2392 | * Aggregate cfs_rq runnable averages into an equivalent task_group | |
2393 | * representation for computing load contributions. | |
2394 | */ | |
2395 | static inline void __update_tg_runnable_avg(struct sched_avg *sa, | |
2396 | struct cfs_rq *cfs_rq) | |
2397 | { | |
2398 | struct task_group *tg = cfs_rq->tg; | |
2399 | long contrib; | |
2400 | ||
2401 | /* The fraction of a cpu used by this cfs_rq */ | |
85b088e9 | 2402 | contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT, |
bb17f655 PT |
2403 | sa->runnable_avg_period + 1); |
2404 | contrib -= cfs_rq->tg_runnable_contrib; | |
2405 | ||
2406 | if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) { | |
2407 | atomic_add(contrib, &tg->runnable_avg); | |
2408 | cfs_rq->tg_runnable_contrib += contrib; | |
2409 | } | |
2410 | } | |
2411 | ||
8165e145 PT |
2412 | static inline void __update_group_entity_contrib(struct sched_entity *se) |
2413 | { | |
2414 | struct cfs_rq *cfs_rq = group_cfs_rq(se); | |
2415 | struct task_group *tg = cfs_rq->tg; | |
bb17f655 PT |
2416 | int runnable_avg; |
2417 | ||
8165e145 PT |
2418 | u64 contrib; |
2419 | ||
2420 | contrib = cfs_rq->tg_load_contrib * tg->shares; | |
bf5b986e AS |
2421 | se->avg.load_avg_contrib = div_u64(contrib, |
2422 | atomic_long_read(&tg->load_avg) + 1); | |
bb17f655 PT |
2423 | |
2424 | /* | |
2425 | * For group entities we need to compute a correction term in the case | |
2426 | * that they are consuming <1 cpu so that we would contribute the same | |
2427 | * load as a task of equal weight. | |
2428 | * | |
2429 | * Explicitly co-ordinating this measurement would be expensive, but | |
2430 | * fortunately the sum of each cpus contribution forms a usable | |
2431 | * lower-bound on the true value. | |
2432 | * | |
2433 | * Consider the aggregate of 2 contributions. Either they are disjoint | |
2434 | * (and the sum represents true value) or they are disjoint and we are | |
2435 | * understating by the aggregate of their overlap. | |
2436 | * | |
2437 | * Extending this to N cpus, for a given overlap, the maximum amount we | |
2438 | * understand is then n_i(n_i+1)/2 * w_i where n_i is the number of | |
2439 | * cpus that overlap for this interval and w_i is the interval width. | |
2440 | * | |
2441 | * On a small machine; the first term is well-bounded which bounds the | |
2442 | * total error since w_i is a subset of the period. Whereas on a | |
2443 | * larger machine, while this first term can be larger, if w_i is the | |
2444 | * of consequential size guaranteed to see n_i*w_i quickly converge to | |
2445 | * our upper bound of 1-cpu. | |
2446 | */ | |
2447 | runnable_avg = atomic_read(&tg->runnable_avg); | |
2448 | if (runnable_avg < NICE_0_LOAD) { | |
2449 | se->avg.load_avg_contrib *= runnable_avg; | |
2450 | se->avg.load_avg_contrib >>= NICE_0_SHIFT; | |
2451 | } | |
8165e145 | 2452 | } |
f5f9739d DE |
2453 | |
2454 | static inline void update_rq_runnable_avg(struct rq *rq, int runnable) | |
2455 | { | |
2456 | __update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable); | |
2457 | __update_tg_runnable_avg(&rq->avg, &rq->cfs); | |
2458 | } | |
6e83125c | 2459 | #else /* CONFIG_FAIR_GROUP_SCHED */ |
c566e8e9 PT |
2460 | static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, |
2461 | int force_update) {} | |
bb17f655 PT |
2462 | static inline void __update_tg_runnable_avg(struct sched_avg *sa, |
2463 | struct cfs_rq *cfs_rq) {} | |
8165e145 | 2464 | static inline void __update_group_entity_contrib(struct sched_entity *se) {} |
f5f9739d | 2465 | static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {} |
6e83125c | 2466 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
c566e8e9 | 2467 | |
8165e145 PT |
2468 | static inline void __update_task_entity_contrib(struct sched_entity *se) |
2469 | { | |
2470 | u32 contrib; | |
2471 | ||
2472 | /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */ | |
2473 | contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight); | |
2474 | contrib /= (se->avg.runnable_avg_period + 1); | |
2475 | se->avg.load_avg_contrib = scale_load(contrib); | |
2476 | } | |
2477 | ||
2dac754e PT |
2478 | /* Compute the current contribution to load_avg by se, return any delta */ |
2479 | static long __update_entity_load_avg_contrib(struct sched_entity *se) | |
2480 | { | |
2481 | long old_contrib = se->avg.load_avg_contrib; | |
2482 | ||
8165e145 PT |
2483 | if (entity_is_task(se)) { |
2484 | __update_task_entity_contrib(se); | |
2485 | } else { | |
bb17f655 | 2486 | __update_tg_runnable_avg(&se->avg, group_cfs_rq(se)); |
8165e145 PT |
2487 | __update_group_entity_contrib(se); |
2488 | } | |
2dac754e PT |
2489 | |
2490 | return se->avg.load_avg_contrib - old_contrib; | |
2491 | } | |
2492 | ||
9ee474f5 PT |
2493 | static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq, |
2494 | long load_contrib) | |
2495 | { | |
2496 | if (likely(load_contrib < cfs_rq->blocked_load_avg)) | |
2497 | cfs_rq->blocked_load_avg -= load_contrib; | |
2498 | else | |
2499 | cfs_rq->blocked_load_avg = 0; | |
2500 | } | |
2501 | ||
f1b17280 PT |
2502 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); |
2503 | ||
9d85f21c | 2504 | /* Update a sched_entity's runnable average */ |
9ee474f5 PT |
2505 | static inline void update_entity_load_avg(struct sched_entity *se, |
2506 | int update_cfs_rq) | |
9d85f21c | 2507 | { |
2dac754e PT |
2508 | struct cfs_rq *cfs_rq = cfs_rq_of(se); |
2509 | long contrib_delta; | |
f1b17280 | 2510 | u64 now; |
2dac754e | 2511 | |
f1b17280 PT |
2512 | /* |
2513 | * For a group entity we need to use their owned cfs_rq_clock_task() in | |
2514 | * case they are the parent of a throttled hierarchy. | |
2515 | */ | |
2516 | if (entity_is_task(se)) | |
2517 | now = cfs_rq_clock_task(cfs_rq); | |
2518 | else | |
2519 | now = cfs_rq_clock_task(group_cfs_rq(se)); | |
2520 | ||
2521 | if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq)) | |
2dac754e PT |
2522 | return; |
2523 | ||
2524 | contrib_delta = __update_entity_load_avg_contrib(se); | |
9ee474f5 PT |
2525 | |
2526 | if (!update_cfs_rq) | |
2527 | return; | |
2528 | ||
2dac754e PT |
2529 | if (se->on_rq) |
2530 | cfs_rq->runnable_load_avg += contrib_delta; | |
9ee474f5 PT |
2531 | else |
2532 | subtract_blocked_load_contrib(cfs_rq, -contrib_delta); | |
2533 | } | |
2534 | ||
2535 | /* | |
2536 | * Decay the load contributed by all blocked children and account this so that | |
2537 | * their contribution may appropriately discounted when they wake up. | |
2538 | */ | |
aff3e498 | 2539 | static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update) |
9ee474f5 | 2540 | { |
f1b17280 | 2541 | u64 now = cfs_rq_clock_task(cfs_rq) >> 20; |
9ee474f5 PT |
2542 | u64 decays; |
2543 | ||
2544 | decays = now - cfs_rq->last_decay; | |
aff3e498 | 2545 | if (!decays && !force_update) |
9ee474f5 PT |
2546 | return; |
2547 | ||
2509940f AS |
2548 | if (atomic_long_read(&cfs_rq->removed_load)) { |
2549 | unsigned long removed_load; | |
2550 | removed_load = atomic_long_xchg(&cfs_rq->removed_load, 0); | |
aff3e498 PT |
2551 | subtract_blocked_load_contrib(cfs_rq, removed_load); |
2552 | } | |
9ee474f5 | 2553 | |
aff3e498 PT |
2554 | if (decays) { |
2555 | cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg, | |
2556 | decays); | |
2557 | atomic64_add(decays, &cfs_rq->decay_counter); | |
2558 | cfs_rq->last_decay = now; | |
2559 | } | |
c566e8e9 PT |
2560 | |
2561 | __update_cfs_rq_tg_load_contrib(cfs_rq, force_update); | |
9d85f21c | 2562 | } |
18bf2805 | 2563 | |
2dac754e PT |
2564 | /* Add the load generated by se into cfs_rq's child load-average */ |
2565 | static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, | |
9ee474f5 PT |
2566 | struct sched_entity *se, |
2567 | int wakeup) | |
2dac754e | 2568 | { |
aff3e498 PT |
2569 | /* |
2570 | * We track migrations using entity decay_count <= 0, on a wake-up | |
2571 | * migration we use a negative decay count to track the remote decays | |
2572 | * accumulated while sleeping. | |
a75cdaa9 AS |
2573 | * |
2574 | * Newly forked tasks are enqueued with se->avg.decay_count == 0, they | |
2575 | * are seen by enqueue_entity_load_avg() as a migration with an already | |
2576 | * constructed load_avg_contrib. | |
aff3e498 PT |
2577 | */ |
2578 | if (unlikely(se->avg.decay_count <= 0)) { | |
78becc27 | 2579 | se->avg.last_runnable_update = rq_clock_task(rq_of(cfs_rq)); |
aff3e498 PT |
2580 | if (se->avg.decay_count) { |
2581 | /* | |
2582 | * In a wake-up migration we have to approximate the | |
2583 | * time sleeping. This is because we can't synchronize | |
2584 | * clock_task between the two cpus, and it is not | |
2585 | * guaranteed to be read-safe. Instead, we can | |
2586 | * approximate this using our carried decays, which are | |
2587 | * explicitly atomically readable. | |
2588 | */ | |
2589 | se->avg.last_runnable_update -= (-se->avg.decay_count) | |
2590 | << 20; | |
2591 | update_entity_load_avg(se, 0); | |
2592 | /* Indicate that we're now synchronized and on-rq */ | |
2593 | se->avg.decay_count = 0; | |
2594 | } | |
9ee474f5 PT |
2595 | wakeup = 0; |
2596 | } else { | |
9390675a | 2597 | __synchronize_entity_decay(se); |
9ee474f5 PT |
2598 | } |
2599 | ||
aff3e498 PT |
2600 | /* migrated tasks did not contribute to our blocked load */ |
2601 | if (wakeup) { | |
9ee474f5 | 2602 | subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib); |
aff3e498 PT |
2603 | update_entity_load_avg(se, 0); |
2604 | } | |
9ee474f5 | 2605 | |
2dac754e | 2606 | cfs_rq->runnable_load_avg += se->avg.load_avg_contrib; |
aff3e498 PT |
2607 | /* we force update consideration on load-balancer moves */ |
2608 | update_cfs_rq_blocked_load(cfs_rq, !wakeup); | |
2dac754e PT |
2609 | } |
2610 | ||
9ee474f5 PT |
2611 | /* |
2612 | * Remove se's load from this cfs_rq child load-average, if the entity is | |
2613 | * transitioning to a blocked state we track its projected decay using | |
2614 | * blocked_load_avg. | |
2615 | */ | |
2dac754e | 2616 | static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, |
9ee474f5 PT |
2617 | struct sched_entity *se, |
2618 | int sleep) | |
2dac754e | 2619 | { |
9ee474f5 | 2620 | update_entity_load_avg(se, 1); |
aff3e498 PT |
2621 | /* we force update consideration on load-balancer moves */ |
2622 | update_cfs_rq_blocked_load(cfs_rq, !sleep); | |
9ee474f5 | 2623 | |
2dac754e | 2624 | cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib; |
9ee474f5 PT |
2625 | if (sleep) { |
2626 | cfs_rq->blocked_load_avg += se->avg.load_avg_contrib; | |
2627 | se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter); | |
2628 | } /* migrations, e.g. sleep=0 leave decay_count == 0 */ | |
2dac754e | 2629 | } |
642dbc39 VG |
2630 | |
2631 | /* | |
2632 | * Update the rq's load with the elapsed running time before entering | |
2633 | * idle. if the last scheduled task is not a CFS task, idle_enter will | |
2634 | * be the only way to update the runnable statistic. | |
2635 | */ | |
2636 | void idle_enter_fair(struct rq *this_rq) | |
2637 | { | |
2638 | update_rq_runnable_avg(this_rq, 1); | |
2639 | } | |
2640 | ||
2641 | /* | |
2642 | * Update the rq's load with the elapsed idle time before a task is | |
2643 | * scheduled. if the newly scheduled task is not a CFS task, idle_exit will | |
2644 | * be the only way to update the runnable statistic. | |
2645 | */ | |
2646 | void idle_exit_fair(struct rq *this_rq) | |
2647 | { | |
2648 | update_rq_runnable_avg(this_rq, 0); | |
2649 | } | |
2650 | ||
6e83125c PZ |
2651 | static int idle_balance(struct rq *this_rq); |
2652 | ||
38033c37 PZ |
2653 | #else /* CONFIG_SMP */ |
2654 | ||
9ee474f5 PT |
2655 | static inline void update_entity_load_avg(struct sched_entity *se, |
2656 | int update_cfs_rq) {} | |
18bf2805 | 2657 | static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {} |
2dac754e | 2658 | static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, |
9ee474f5 PT |
2659 | struct sched_entity *se, |
2660 | int wakeup) {} | |
2dac754e | 2661 | static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, |
9ee474f5 PT |
2662 | struct sched_entity *se, |
2663 | int sleep) {} | |
aff3e498 PT |
2664 | static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, |
2665 | int force_update) {} | |
6e83125c PZ |
2666 | |
2667 | static inline int idle_balance(struct rq *rq) | |
2668 | { | |
2669 | return 0; | |
2670 | } | |
2671 | ||
38033c37 | 2672 | #endif /* CONFIG_SMP */ |
9d85f21c | 2673 | |
2396af69 | 2674 | static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 2675 | { |
bf0f6f24 | 2676 | #ifdef CONFIG_SCHEDSTATS |
e414314c PZ |
2677 | struct task_struct *tsk = NULL; |
2678 | ||
2679 | if (entity_is_task(se)) | |
2680 | tsk = task_of(se); | |
2681 | ||
41acab88 | 2682 | if (se->statistics.sleep_start) { |
78becc27 | 2683 | u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.sleep_start; |
bf0f6f24 IM |
2684 | |
2685 | if ((s64)delta < 0) | |
2686 | delta = 0; | |
2687 | ||
41acab88 LDM |
2688 | if (unlikely(delta > se->statistics.sleep_max)) |
2689 | se->statistics.sleep_max = delta; | |
bf0f6f24 | 2690 | |
8c79a045 | 2691 | se->statistics.sleep_start = 0; |
41acab88 | 2692 | se->statistics.sum_sleep_runtime += delta; |
9745512c | 2693 | |
768d0c27 | 2694 | if (tsk) { |
e414314c | 2695 | account_scheduler_latency(tsk, delta >> 10, 1); |
768d0c27 PZ |
2696 | trace_sched_stat_sleep(tsk, delta); |
2697 | } | |
bf0f6f24 | 2698 | } |
41acab88 | 2699 | if (se->statistics.block_start) { |
78becc27 | 2700 | u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.block_start; |
bf0f6f24 IM |
2701 | |
2702 | if ((s64)delta < 0) | |
2703 | delta = 0; | |
2704 | ||
41acab88 LDM |
2705 | if (unlikely(delta > se->statistics.block_max)) |
2706 | se->statistics.block_max = delta; | |
bf0f6f24 | 2707 | |
8c79a045 | 2708 | se->statistics.block_start = 0; |
41acab88 | 2709 | se->statistics.sum_sleep_runtime += delta; |
30084fbd | 2710 | |
e414314c | 2711 | if (tsk) { |
8f0dfc34 | 2712 | if (tsk->in_iowait) { |
41acab88 LDM |
2713 | se->statistics.iowait_sum += delta; |
2714 | se->statistics.iowait_count++; | |
768d0c27 | 2715 | trace_sched_stat_iowait(tsk, delta); |
8f0dfc34 AV |
2716 | } |
2717 | ||
b781a602 AV |
2718 | trace_sched_stat_blocked(tsk, delta); |
2719 | ||
e414314c PZ |
2720 | /* |
2721 | * Blocking time is in units of nanosecs, so shift by | |
2722 | * 20 to get a milliseconds-range estimation of the | |
2723 | * amount of time that the task spent sleeping: | |
2724 | */ | |
2725 | if (unlikely(prof_on == SLEEP_PROFILING)) { | |
2726 | profile_hits(SLEEP_PROFILING, | |
2727 | (void *)get_wchan(tsk), | |
2728 | delta >> 20); | |
2729 | } | |
2730 | account_scheduler_latency(tsk, delta >> 10, 0); | |
30084fbd | 2731 | } |
bf0f6f24 IM |
2732 | } |
2733 | #endif | |
2734 | } | |
2735 | ||
ddc97297 PZ |
2736 | static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se) |
2737 | { | |
2738 | #ifdef CONFIG_SCHED_DEBUG | |
2739 | s64 d = se->vruntime - cfs_rq->min_vruntime; | |
2740 | ||
2741 | if (d < 0) | |
2742 | d = -d; | |
2743 | ||
2744 | if (d > 3*sysctl_sched_latency) | |
2745 | schedstat_inc(cfs_rq, nr_spread_over); | |
2746 | #endif | |
2747 | } | |
2748 | ||
aeb73b04 PZ |
2749 | static void |
2750 | place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) | |
2751 | { | |
1af5f730 | 2752 | u64 vruntime = cfs_rq->min_vruntime; |
94dfb5e7 | 2753 | |
2cb8600e PZ |
2754 | /* |
2755 | * The 'current' period is already promised to the current tasks, | |
2756 | * however the extra weight of the new task will slow them down a | |
2757 | * little, place the new task so that it fits in the slot that | |
2758 | * stays open at the end. | |
2759 | */ | |
94dfb5e7 | 2760 | if (initial && sched_feat(START_DEBIT)) |
f9c0b095 | 2761 | vruntime += sched_vslice(cfs_rq, se); |
aeb73b04 | 2762 | |
a2e7a7eb | 2763 | /* sleeps up to a single latency don't count. */ |
5ca9880c | 2764 | if (!initial) { |
a2e7a7eb | 2765 | unsigned long thresh = sysctl_sched_latency; |
a7be37ac | 2766 | |
a2e7a7eb MG |
2767 | /* |
2768 | * Halve their sleep time's effect, to allow | |
2769 | * for a gentler effect of sleepers: | |
2770 | */ | |
2771 | if (sched_feat(GENTLE_FAIR_SLEEPERS)) | |
2772 | thresh >>= 1; | |
51e0304c | 2773 | |
a2e7a7eb | 2774 | vruntime -= thresh; |
aeb73b04 PZ |
2775 | } |
2776 | ||
b5d9d734 | 2777 | /* ensure we never gain time by being placed backwards. */ |
16c8f1c7 | 2778 | se->vruntime = max_vruntime(se->vruntime, vruntime); |
aeb73b04 PZ |
2779 | } |
2780 | ||
d3d9dc33 PT |
2781 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq); |
2782 | ||
bf0f6f24 | 2783 | static void |
88ec22d3 | 2784 | enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 2785 | { |
88ec22d3 PZ |
2786 | /* |
2787 | * Update the normalized vruntime before updating min_vruntime | |
0fc576d5 | 2788 | * through calling update_curr(). |
88ec22d3 | 2789 | */ |
371fd7e7 | 2790 | if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING)) |
88ec22d3 PZ |
2791 | se->vruntime += cfs_rq->min_vruntime; |
2792 | ||
bf0f6f24 | 2793 | /* |
a2a2d680 | 2794 | * Update run-time statistics of the 'current'. |
bf0f6f24 | 2795 | */ |
b7cc0896 | 2796 | update_curr(cfs_rq); |
f269ae04 | 2797 | enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP); |
17bc14b7 LT |
2798 | account_entity_enqueue(cfs_rq, se); |
2799 | update_cfs_shares(cfs_rq); | |
bf0f6f24 | 2800 | |
88ec22d3 | 2801 | if (flags & ENQUEUE_WAKEUP) { |
aeb73b04 | 2802 | place_entity(cfs_rq, se, 0); |
2396af69 | 2803 | enqueue_sleeper(cfs_rq, se); |
e9acbff6 | 2804 | } |
bf0f6f24 | 2805 | |
d2417e5a | 2806 | update_stats_enqueue(cfs_rq, se); |
ddc97297 | 2807 | check_spread(cfs_rq, se); |
83b699ed SV |
2808 | if (se != cfs_rq->curr) |
2809 | __enqueue_entity(cfs_rq, se); | |
2069dd75 | 2810 | se->on_rq = 1; |
3d4b47b4 | 2811 | |
d3d9dc33 | 2812 | if (cfs_rq->nr_running == 1) { |
3d4b47b4 | 2813 | list_add_leaf_cfs_rq(cfs_rq); |
d3d9dc33 PT |
2814 | check_enqueue_throttle(cfs_rq); |
2815 | } | |
bf0f6f24 IM |
2816 | } |
2817 | ||
2c13c919 | 2818 | static void __clear_buddies_last(struct sched_entity *se) |
2002c695 | 2819 | { |
2c13c919 RR |
2820 | for_each_sched_entity(se) { |
2821 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 2822 | if (cfs_rq->last != se) |
2c13c919 | 2823 | break; |
f1044799 PZ |
2824 | |
2825 | cfs_rq->last = NULL; | |
2c13c919 RR |
2826 | } |
2827 | } | |
2002c695 | 2828 | |
2c13c919 RR |
2829 | static void __clear_buddies_next(struct sched_entity *se) |
2830 | { | |
2831 | for_each_sched_entity(se) { | |
2832 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 2833 | if (cfs_rq->next != se) |
2c13c919 | 2834 | break; |
f1044799 PZ |
2835 | |
2836 | cfs_rq->next = NULL; | |
2c13c919 | 2837 | } |
2002c695 PZ |
2838 | } |
2839 | ||
ac53db59 RR |
2840 | static void __clear_buddies_skip(struct sched_entity *se) |
2841 | { | |
2842 | for_each_sched_entity(se) { | |
2843 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
f1044799 | 2844 | if (cfs_rq->skip != se) |
ac53db59 | 2845 | break; |
f1044799 PZ |
2846 | |
2847 | cfs_rq->skip = NULL; | |
ac53db59 RR |
2848 | } |
2849 | } | |
2850 | ||
a571bbea PZ |
2851 | static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) |
2852 | { | |
2c13c919 RR |
2853 | if (cfs_rq->last == se) |
2854 | __clear_buddies_last(se); | |
2855 | ||
2856 | if (cfs_rq->next == se) | |
2857 | __clear_buddies_next(se); | |
ac53db59 RR |
2858 | |
2859 | if (cfs_rq->skip == se) | |
2860 | __clear_buddies_skip(se); | |
a571bbea PZ |
2861 | } |
2862 | ||
6c16a6dc | 2863 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
d8b4986d | 2864 | |
bf0f6f24 | 2865 | static void |
371fd7e7 | 2866 | dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
bf0f6f24 | 2867 | { |
a2a2d680 DA |
2868 | /* |
2869 | * Update run-time statistics of the 'current'. | |
2870 | */ | |
2871 | update_curr(cfs_rq); | |
17bc14b7 | 2872 | dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP); |
a2a2d680 | 2873 | |
19b6a2e3 | 2874 | update_stats_dequeue(cfs_rq, se); |
371fd7e7 | 2875 | if (flags & DEQUEUE_SLEEP) { |
67e9fb2a | 2876 | #ifdef CONFIG_SCHEDSTATS |
bf0f6f24 IM |
2877 | if (entity_is_task(se)) { |
2878 | struct task_struct *tsk = task_of(se); | |
2879 | ||
2880 | if (tsk->state & TASK_INTERRUPTIBLE) | |
78becc27 | 2881 | se->statistics.sleep_start = rq_clock(rq_of(cfs_rq)); |
bf0f6f24 | 2882 | if (tsk->state & TASK_UNINTERRUPTIBLE) |
78becc27 | 2883 | se->statistics.block_start = rq_clock(rq_of(cfs_rq)); |
bf0f6f24 | 2884 | } |
db36cc7d | 2885 | #endif |
67e9fb2a PZ |
2886 | } |
2887 | ||
2002c695 | 2888 | clear_buddies(cfs_rq, se); |
4793241b | 2889 | |
83b699ed | 2890 | if (se != cfs_rq->curr) |
30cfdcfc | 2891 | __dequeue_entity(cfs_rq, se); |
17bc14b7 | 2892 | se->on_rq = 0; |
30cfdcfc | 2893 | account_entity_dequeue(cfs_rq, se); |
88ec22d3 PZ |
2894 | |
2895 | /* | |
2896 | * Normalize the entity after updating the min_vruntime because the | |
2897 | * update can refer to the ->curr item and we need to reflect this | |
2898 | * movement in our normalized position. | |
2899 | */ | |
371fd7e7 | 2900 | if (!(flags & DEQUEUE_SLEEP)) |
88ec22d3 | 2901 | se->vruntime -= cfs_rq->min_vruntime; |
1e876231 | 2902 | |
d8b4986d PT |
2903 | /* return excess runtime on last dequeue */ |
2904 | return_cfs_rq_runtime(cfs_rq); | |
2905 | ||
1e876231 | 2906 | update_min_vruntime(cfs_rq); |
17bc14b7 | 2907 | update_cfs_shares(cfs_rq); |
bf0f6f24 IM |
2908 | } |
2909 | ||
2910 | /* | |
2911 | * Preempt the current task with a newly woken task if needed: | |
2912 | */ | |
7c92e54f | 2913 | static void |
2e09bf55 | 2914 | check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
bf0f6f24 | 2915 | { |
11697830 | 2916 | unsigned long ideal_runtime, delta_exec; |
f4cfb33e WX |
2917 | struct sched_entity *se; |
2918 | s64 delta; | |
11697830 | 2919 | |
6d0f0ebd | 2920 | ideal_runtime = sched_slice(cfs_rq, curr); |
11697830 | 2921 | delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; |
a9f3e2b5 | 2922 | if (delta_exec > ideal_runtime) { |
8875125e | 2923 | resched_curr(rq_of(cfs_rq)); |
a9f3e2b5 MG |
2924 | /* |
2925 | * The current task ran long enough, ensure it doesn't get | |
2926 | * re-elected due to buddy favours. | |
2927 | */ | |
2928 | clear_buddies(cfs_rq, curr); | |
f685ceac MG |
2929 | return; |
2930 | } | |
2931 | ||
2932 | /* | |
2933 | * Ensure that a task that missed wakeup preemption by a | |
2934 | * narrow margin doesn't have to wait for a full slice. | |
2935 | * This also mitigates buddy induced latencies under load. | |
2936 | */ | |
f685ceac MG |
2937 | if (delta_exec < sysctl_sched_min_granularity) |
2938 | return; | |
2939 | ||
f4cfb33e WX |
2940 | se = __pick_first_entity(cfs_rq); |
2941 | delta = curr->vruntime - se->vruntime; | |
f685ceac | 2942 | |
f4cfb33e WX |
2943 | if (delta < 0) |
2944 | return; | |
d7d82944 | 2945 | |
f4cfb33e | 2946 | if (delta > ideal_runtime) |
8875125e | 2947 | resched_curr(rq_of(cfs_rq)); |
bf0f6f24 IM |
2948 | } |
2949 | ||
83b699ed | 2950 | static void |
8494f412 | 2951 | set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
bf0f6f24 | 2952 | { |
83b699ed SV |
2953 | /* 'current' is not kept within the tree. */ |
2954 | if (se->on_rq) { | |
2955 | /* | |
2956 | * Any task has to be enqueued before it get to execute on | |
2957 | * a CPU. So account for the time it spent waiting on the | |
2958 | * runqueue. | |
2959 | */ | |
2960 | update_stats_wait_end(cfs_rq, se); | |
2961 | __dequeue_entity(cfs_rq, se); | |
2962 | } | |
2963 | ||
79303e9e | 2964 | update_stats_curr_start(cfs_rq, se); |
429d43bc | 2965 | cfs_rq->curr = se; |
eba1ed4b IM |
2966 | #ifdef CONFIG_SCHEDSTATS |
2967 | /* | |
2968 | * Track our maximum slice length, if the CPU's load is at | |
2969 | * least twice that of our own weight (i.e. dont track it | |
2970 | * when there are only lesser-weight tasks around): | |
2971 | */ | |
495eca49 | 2972 | if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) { |
41acab88 | 2973 | se->statistics.slice_max = max(se->statistics.slice_max, |
eba1ed4b IM |
2974 | se->sum_exec_runtime - se->prev_sum_exec_runtime); |
2975 | } | |
2976 | #endif | |
4a55b450 | 2977 | se->prev_sum_exec_runtime = se->sum_exec_runtime; |
bf0f6f24 IM |
2978 | } |
2979 | ||
3f3a4904 PZ |
2980 | static int |
2981 | wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se); | |
2982 | ||
ac53db59 RR |
2983 | /* |
2984 | * Pick the next process, keeping these things in mind, in this order: | |
2985 | * 1) keep things fair between processes/task groups | |
2986 | * 2) pick the "next" process, since someone really wants that to run | |
2987 | * 3) pick the "last" process, for cache locality | |
2988 | * 4) do not run the "skip" process, if something else is available | |
2989 | */ | |
678d5718 PZ |
2990 | static struct sched_entity * |
2991 | pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) | |
aa2ac252 | 2992 | { |
678d5718 PZ |
2993 | struct sched_entity *left = __pick_first_entity(cfs_rq); |
2994 | struct sched_entity *se; | |
2995 | ||
2996 | /* | |
2997 | * If curr is set we have to see if its left of the leftmost entity | |
2998 | * still in the tree, provided there was anything in the tree at all. | |
2999 | */ | |
3000 | if (!left || (curr && entity_before(curr, left))) | |
3001 | left = curr; | |
3002 | ||
3003 | se = left; /* ideally we run the leftmost entity */ | |
f4b6755f | 3004 | |
ac53db59 RR |
3005 | /* |
3006 | * Avoid running the skip buddy, if running something else can | |
3007 | * be done without getting too unfair. | |
3008 | */ | |
3009 | if (cfs_rq->skip == se) { | |
678d5718 PZ |
3010 | struct sched_entity *second; |
3011 | ||
3012 | if (se == curr) { | |
3013 | second = __pick_first_entity(cfs_rq); | |
3014 | } else { | |
3015 | second = __pick_next_entity(se); | |
3016 | if (!second || (curr && entity_before(curr, second))) | |
3017 | second = curr; | |
3018 | } | |
3019 | ||
ac53db59 RR |
3020 | if (second && wakeup_preempt_entity(second, left) < 1) |
3021 | se = second; | |
3022 | } | |
aa2ac252 | 3023 | |
f685ceac MG |
3024 | /* |
3025 | * Prefer last buddy, try to return the CPU to a preempted task. | |
3026 | */ | |
3027 | if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) | |
3028 | se = cfs_rq->last; | |
3029 | ||
ac53db59 RR |
3030 | /* |
3031 | * Someone really wants this to run. If it's not unfair, run it. | |
3032 | */ | |
3033 | if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) | |
3034 | se = cfs_rq->next; | |
3035 | ||
f685ceac | 3036 | clear_buddies(cfs_rq, se); |
4793241b PZ |
3037 | |
3038 | return se; | |
aa2ac252 PZ |
3039 | } |
3040 | ||
678d5718 | 3041 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
d3d9dc33 | 3042 | |
ab6cde26 | 3043 | static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) |
bf0f6f24 IM |
3044 | { |
3045 | /* | |
3046 | * If still on the runqueue then deactivate_task() | |
3047 | * was not called and update_curr() has to be done: | |
3048 | */ | |
3049 | if (prev->on_rq) | |
b7cc0896 | 3050 | update_curr(cfs_rq); |
bf0f6f24 | 3051 | |
d3d9dc33 PT |
3052 | /* throttle cfs_rqs exceeding runtime */ |
3053 | check_cfs_rq_runtime(cfs_rq); | |
3054 | ||
ddc97297 | 3055 | check_spread(cfs_rq, prev); |
30cfdcfc | 3056 | if (prev->on_rq) { |
5870db5b | 3057 | update_stats_wait_start(cfs_rq, prev); |
30cfdcfc DA |
3058 | /* Put 'current' back into the tree. */ |
3059 | __enqueue_entity(cfs_rq, prev); | |
9d85f21c | 3060 | /* in !on_rq case, update occurred at dequeue */ |
9ee474f5 | 3061 | update_entity_load_avg(prev, 1); |
30cfdcfc | 3062 | } |
429d43bc | 3063 | cfs_rq->curr = NULL; |
bf0f6f24 IM |
3064 | } |
3065 | ||
8f4d37ec PZ |
3066 | static void |
3067 | entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) | |
bf0f6f24 | 3068 | { |
bf0f6f24 | 3069 | /* |
30cfdcfc | 3070 | * Update run-time statistics of the 'current'. |
bf0f6f24 | 3071 | */ |
30cfdcfc | 3072 | update_curr(cfs_rq); |
bf0f6f24 | 3073 | |
9d85f21c PT |
3074 | /* |
3075 | * Ensure that runnable average is periodically updated. | |
3076 | */ | |
9ee474f5 | 3077 | update_entity_load_avg(curr, 1); |
aff3e498 | 3078 | update_cfs_rq_blocked_load(cfs_rq, 1); |
bf0bd948 | 3079 | update_cfs_shares(cfs_rq); |
9d85f21c | 3080 | |
8f4d37ec PZ |
3081 | #ifdef CONFIG_SCHED_HRTICK |
3082 | /* | |
3083 | * queued ticks are scheduled to match the slice, so don't bother | |
3084 | * validating it and just reschedule. | |
3085 | */ | |
983ed7a6 | 3086 | if (queued) { |
8875125e | 3087 | resched_curr(rq_of(cfs_rq)); |
983ed7a6 HH |
3088 | return; |
3089 | } | |
8f4d37ec PZ |
3090 | /* |
3091 | * don't let the period tick interfere with the hrtick preemption | |
3092 | */ | |
3093 | if (!sched_feat(DOUBLE_TICK) && | |
3094 | hrtimer_active(&rq_of(cfs_rq)->hrtick_timer)) | |
3095 | return; | |
3096 | #endif | |
3097 | ||
2c2efaed | 3098 | if (cfs_rq->nr_running > 1) |
2e09bf55 | 3099 | check_preempt_tick(cfs_rq, curr); |
bf0f6f24 IM |
3100 | } |
3101 | ||
ab84d31e PT |
3102 | |
3103 | /************************************************** | |
3104 | * CFS bandwidth control machinery | |
3105 | */ | |
3106 | ||
3107 | #ifdef CONFIG_CFS_BANDWIDTH | |
029632fb PZ |
3108 | |
3109 | #ifdef HAVE_JUMP_LABEL | |
c5905afb | 3110 | static struct static_key __cfs_bandwidth_used; |
029632fb PZ |
3111 | |
3112 | static inline bool cfs_bandwidth_used(void) | |
3113 | { | |
c5905afb | 3114 | return static_key_false(&__cfs_bandwidth_used); |
029632fb PZ |
3115 | } |
3116 | ||
1ee14e6c | 3117 | void cfs_bandwidth_usage_inc(void) |
029632fb | 3118 | { |
1ee14e6c BS |
3119 | static_key_slow_inc(&__cfs_bandwidth_used); |
3120 | } | |
3121 | ||
3122 | void cfs_bandwidth_usage_dec(void) | |
3123 | { | |
3124 | static_key_slow_dec(&__cfs_bandwidth_used); | |
029632fb PZ |
3125 | } |
3126 | #else /* HAVE_JUMP_LABEL */ | |
3127 | static bool cfs_bandwidth_used(void) | |
3128 | { | |
3129 | return true; | |
3130 | } | |
3131 | ||
1ee14e6c BS |
3132 | void cfs_bandwidth_usage_inc(void) {} |
3133 | void cfs_bandwidth_usage_dec(void) {} | |
029632fb PZ |
3134 | #endif /* HAVE_JUMP_LABEL */ |
3135 | ||
ab84d31e PT |
3136 | /* |
3137 | * default period for cfs group bandwidth. | |
3138 | * default: 0.1s, units: nanoseconds | |
3139 | */ | |
3140 | static inline u64 default_cfs_period(void) | |
3141 | { | |
3142 | return 100000000ULL; | |
3143 | } | |
ec12cb7f PT |
3144 | |
3145 | static inline u64 sched_cfs_bandwidth_slice(void) | |
3146 | { | |
3147 | return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC; | |
3148 | } | |
3149 | ||
a9cf55b2 PT |
3150 | /* |
3151 | * Replenish runtime according to assigned quota and update expiration time. | |
3152 | * We use sched_clock_cpu directly instead of rq->clock to avoid adding | |
3153 | * additional synchronization around rq->lock. | |
3154 | * | |
3155 | * requires cfs_b->lock | |
3156 | */ | |
029632fb | 3157 | void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b) |
a9cf55b2 PT |
3158 | { |
3159 | u64 now; | |
3160 | ||
3161 | if (cfs_b->quota == RUNTIME_INF) | |
3162 | return; | |
3163 | ||
3164 | now = sched_clock_cpu(smp_processor_id()); | |
3165 | cfs_b->runtime = cfs_b->quota; | |
3166 | cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period); | |
3167 | } | |
3168 | ||
029632fb PZ |
3169 | static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
3170 | { | |
3171 | return &tg->cfs_bandwidth; | |
3172 | } | |
3173 | ||
f1b17280 PT |
3174 | /* rq->task_clock normalized against any time this cfs_rq has spent throttled */ |
3175 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) | |
3176 | { | |
3177 | if (unlikely(cfs_rq->throttle_count)) | |
3178 | return cfs_rq->throttled_clock_task; | |
3179 | ||
78becc27 | 3180 | return rq_clock_task(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time; |
f1b17280 PT |
3181 | } |
3182 | ||
85dac906 PT |
3183 | /* returns 0 on failure to allocate runtime */ |
3184 | static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
ec12cb7f PT |
3185 | { |
3186 | struct task_group *tg = cfs_rq->tg; | |
3187 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg); | |
a9cf55b2 | 3188 | u64 amount = 0, min_amount, expires; |
ec12cb7f PT |
3189 | |
3190 | /* note: this is a positive sum as runtime_remaining <= 0 */ | |
3191 | min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining; | |
3192 | ||
3193 | raw_spin_lock(&cfs_b->lock); | |
3194 | if (cfs_b->quota == RUNTIME_INF) | |
3195 | amount = min_amount; | |
58088ad0 | 3196 | else { |
a9cf55b2 PT |
3197 | /* |
3198 | * If the bandwidth pool has become inactive, then at least one | |
3199 | * period must have elapsed since the last consumption. | |
3200 | * Refresh the global state and ensure bandwidth timer becomes | |
3201 | * active. | |
3202 | */ | |
3203 | if (!cfs_b->timer_active) { | |
3204 | __refill_cfs_bandwidth_runtime(cfs_b); | |
09dc4ab0 | 3205 | __start_cfs_bandwidth(cfs_b, false); |
a9cf55b2 | 3206 | } |
58088ad0 PT |
3207 | |
3208 | if (cfs_b->runtime > 0) { | |
3209 | amount = min(cfs_b->runtime, min_amount); | |
3210 | cfs_b->runtime -= amount; | |
3211 | cfs_b->idle = 0; | |
3212 | } | |
ec12cb7f | 3213 | } |
a9cf55b2 | 3214 | expires = cfs_b->runtime_expires; |
ec12cb7f PT |
3215 | raw_spin_unlock(&cfs_b->lock); |
3216 | ||
3217 | cfs_rq->runtime_remaining += amount; | |
a9cf55b2 PT |
3218 | /* |
3219 | * we may have advanced our local expiration to account for allowed | |
3220 | * spread between our sched_clock and the one on which runtime was | |
3221 | * issued. | |
3222 | */ | |
3223 | if ((s64)(expires - cfs_rq->runtime_expires) > 0) | |
3224 | cfs_rq->runtime_expires = expires; | |
85dac906 PT |
3225 | |
3226 | return cfs_rq->runtime_remaining > 0; | |
ec12cb7f PT |
3227 | } |
3228 | ||
a9cf55b2 PT |
3229 | /* |
3230 | * Note: This depends on the synchronization provided by sched_clock and the | |
3231 | * fact that rq->clock snapshots this value. | |
3232 | */ | |
3233 | static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
ec12cb7f | 3234 | { |
a9cf55b2 | 3235 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
a9cf55b2 PT |
3236 | |
3237 | /* if the deadline is ahead of our clock, nothing to do */ | |
78becc27 | 3238 | if (likely((s64)(rq_clock(rq_of(cfs_rq)) - cfs_rq->runtime_expires) < 0)) |
ec12cb7f PT |
3239 | return; |
3240 | ||
a9cf55b2 PT |
3241 | if (cfs_rq->runtime_remaining < 0) |
3242 | return; | |
3243 | ||
3244 | /* | |
3245 | * If the local deadline has passed we have to consider the | |
3246 | * possibility that our sched_clock is 'fast' and the global deadline | |
3247 | * has not truly expired. | |
3248 | * | |
3249 | * Fortunately we can check determine whether this the case by checking | |
51f2176d BS |
3250 | * whether the global deadline has advanced. It is valid to compare |
3251 | * cfs_b->runtime_expires without any locks since we only care about | |
3252 | * exact equality, so a partial write will still work. | |
a9cf55b2 PT |
3253 | */ |
3254 | ||
51f2176d | 3255 | if (cfs_rq->runtime_expires != cfs_b->runtime_expires) { |
a9cf55b2 PT |
3256 | /* extend local deadline, drift is bounded above by 2 ticks */ |
3257 | cfs_rq->runtime_expires += TICK_NSEC; | |
3258 | } else { | |
3259 | /* global deadline is ahead, expiration has passed */ | |
3260 | cfs_rq->runtime_remaining = 0; | |
3261 | } | |
3262 | } | |
3263 | ||
9dbdb155 | 3264 | static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
a9cf55b2 PT |
3265 | { |
3266 | /* dock delta_exec before expiring quota (as it could span periods) */ | |
ec12cb7f | 3267 | cfs_rq->runtime_remaining -= delta_exec; |
a9cf55b2 PT |
3268 | expire_cfs_rq_runtime(cfs_rq); |
3269 | ||
3270 | if (likely(cfs_rq->runtime_remaining > 0)) | |
ec12cb7f PT |
3271 | return; |
3272 | ||
85dac906 PT |
3273 | /* |
3274 | * if we're unable to extend our runtime we resched so that the active | |
3275 | * hierarchy can be throttled | |
3276 | */ | |
3277 | if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr)) | |
8875125e | 3278 | resched_curr(rq_of(cfs_rq)); |
ec12cb7f PT |
3279 | } |
3280 | ||
6c16a6dc | 3281 | static __always_inline |
9dbdb155 | 3282 | void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
ec12cb7f | 3283 | { |
56f570e5 | 3284 | if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled) |
ec12cb7f PT |
3285 | return; |
3286 | ||
3287 | __account_cfs_rq_runtime(cfs_rq, delta_exec); | |
3288 | } | |
3289 | ||
85dac906 PT |
3290 | static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) |
3291 | { | |
56f570e5 | 3292 | return cfs_bandwidth_used() && cfs_rq->throttled; |
85dac906 PT |
3293 | } |
3294 | ||
64660c86 PT |
3295 | /* check whether cfs_rq, or any parent, is throttled */ |
3296 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) | |
3297 | { | |
56f570e5 | 3298 | return cfs_bandwidth_used() && cfs_rq->throttle_count; |
64660c86 PT |
3299 | } |
3300 | ||
3301 | /* | |
3302 | * Ensure that neither of the group entities corresponding to src_cpu or | |
3303 | * dest_cpu are members of a throttled hierarchy when performing group | |
3304 | * load-balance operations. | |
3305 | */ | |
3306 | static inline int throttled_lb_pair(struct task_group *tg, | |
3307 | int src_cpu, int dest_cpu) | |
3308 | { | |
3309 | struct cfs_rq *src_cfs_rq, *dest_cfs_rq; | |
3310 | ||
3311 | src_cfs_rq = tg->cfs_rq[src_cpu]; | |
3312 | dest_cfs_rq = tg->cfs_rq[dest_cpu]; | |
3313 | ||
3314 | return throttled_hierarchy(src_cfs_rq) || | |
3315 | throttled_hierarchy(dest_cfs_rq); | |
3316 | } | |
3317 | ||
3318 | /* updated child weight may affect parent so we have to do this bottom up */ | |
3319 | static int tg_unthrottle_up(struct task_group *tg, void *data) | |
3320 | { | |
3321 | struct rq *rq = data; | |
3322 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
3323 | ||
3324 | cfs_rq->throttle_count--; | |
3325 | #ifdef CONFIG_SMP | |
3326 | if (!cfs_rq->throttle_count) { | |
f1b17280 | 3327 | /* adjust cfs_rq_clock_task() */ |
78becc27 | 3328 | cfs_rq->throttled_clock_task_time += rq_clock_task(rq) - |
f1b17280 | 3329 | cfs_rq->throttled_clock_task; |
64660c86 PT |
3330 | } |
3331 | #endif | |
3332 | ||
3333 | return 0; | |
3334 | } | |
3335 | ||
3336 | static int tg_throttle_down(struct task_group *tg, void *data) | |
3337 | { | |
3338 | struct rq *rq = data; | |
3339 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; | |
3340 | ||
82958366 PT |
3341 | /* group is entering throttled state, stop time */ |
3342 | if (!cfs_rq->throttle_count) | |
78becc27 | 3343 | cfs_rq->throttled_clock_task = rq_clock_task(rq); |
64660c86 PT |
3344 | cfs_rq->throttle_count++; |
3345 | ||
3346 | return 0; | |
3347 | } | |
3348 | ||
d3d9dc33 | 3349 | static void throttle_cfs_rq(struct cfs_rq *cfs_rq) |
85dac906 PT |
3350 | { |
3351 | struct rq *rq = rq_of(cfs_rq); | |
3352 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
3353 | struct sched_entity *se; | |
3354 | long task_delta, dequeue = 1; | |
3355 | ||
3356 | se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; | |
3357 | ||
f1b17280 | 3358 | /* freeze hierarchy runnable averages while throttled */ |
64660c86 PT |
3359 | rcu_read_lock(); |
3360 | walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq); | |
3361 | rcu_read_unlock(); | |
85dac906 PT |
3362 | |
3363 | task_delta = cfs_rq->h_nr_running; | |
3364 | for_each_sched_entity(se) { | |
3365 | struct cfs_rq *qcfs_rq = cfs_rq_of(se); | |
3366 | /* throttled entity or throttle-on-deactivate */ | |
3367 | if (!se->on_rq) | |
3368 | break; | |
3369 | ||
3370 | if (dequeue) | |
3371 | dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP); | |
3372 | qcfs_rq->h_nr_running -= task_delta; | |
3373 | ||
3374 | if (qcfs_rq->load.weight) | |
3375 | dequeue = 0; | |
3376 | } | |
3377 | ||
3378 | if (!se) | |
72465447 | 3379 | sub_nr_running(rq, task_delta); |
85dac906 PT |
3380 | |
3381 | cfs_rq->throttled = 1; | |
78becc27 | 3382 | cfs_rq->throttled_clock = rq_clock(rq); |
85dac906 | 3383 | raw_spin_lock(&cfs_b->lock); |
c06f04c7 BS |
3384 | /* |
3385 | * Add to the _head_ of the list, so that an already-started | |
3386 | * distribute_cfs_runtime will not see us | |
3387 | */ | |
3388 | list_add_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); | |
f9f9ffc2 | 3389 | if (!cfs_b->timer_active) |
09dc4ab0 | 3390 | __start_cfs_bandwidth(cfs_b, false); |
85dac906 PT |
3391 | raw_spin_unlock(&cfs_b->lock); |
3392 | } | |
3393 | ||
029632fb | 3394 | void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) |
671fd9da PT |
3395 | { |
3396 | struct rq *rq = rq_of(cfs_rq); | |
3397 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
3398 | struct sched_entity *se; | |
3399 | int enqueue = 1; | |
3400 | long task_delta; | |
3401 | ||
22b958d8 | 3402 | se = cfs_rq->tg->se[cpu_of(rq)]; |
671fd9da PT |
3403 | |
3404 | cfs_rq->throttled = 0; | |
1a55af2e FW |
3405 | |
3406 | update_rq_clock(rq); | |
3407 | ||
671fd9da | 3408 | raw_spin_lock(&cfs_b->lock); |
78becc27 | 3409 | cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock; |
671fd9da PT |
3410 | list_del_rcu(&cfs_rq->throttled_list); |
3411 | raw_spin_unlock(&cfs_b->lock); | |
3412 | ||
64660c86 PT |
3413 | /* update hierarchical throttle state */ |
3414 | walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq); | |
3415 | ||
671fd9da PT |
3416 | if (!cfs_rq->load.weight) |
3417 | return; | |
3418 | ||
3419 | task_delta = cfs_rq->h_nr_running; | |
3420 | for_each_sched_entity(se) { | |
3421 | if (se->on_rq) | |
3422 | enqueue = 0; | |
3423 | ||
3424 | cfs_rq = cfs_rq_of(se); | |
3425 | if (enqueue) | |
3426 | enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); | |
3427 | cfs_rq->h_nr_running += task_delta; | |
3428 | ||
3429 | if (cfs_rq_throttled(cfs_rq)) | |
3430 | break; | |
3431 | } | |
3432 | ||
3433 | if (!se) | |
72465447 | 3434 | add_nr_running(rq, task_delta); |
671fd9da PT |
3435 | |
3436 | /* determine whether we need to wake up potentially idle cpu */ | |
3437 | if (rq->curr == rq->idle && rq->cfs.nr_running) | |
8875125e | 3438 | resched_curr(rq); |
671fd9da PT |
3439 | } |
3440 | ||
3441 | static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, | |
3442 | u64 remaining, u64 expires) | |
3443 | { | |
3444 | struct cfs_rq *cfs_rq; | |
c06f04c7 BS |
3445 | u64 runtime; |
3446 | u64 starting_runtime = remaining; | |
671fd9da PT |
3447 | |
3448 | rcu_read_lock(); | |
3449 | list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq, | |
3450 | throttled_list) { | |
3451 | struct rq *rq = rq_of(cfs_rq); | |
3452 | ||
3453 | raw_spin_lock(&rq->lock); | |
3454 | if (!cfs_rq_throttled(cfs_rq)) | |
3455 | goto next; | |
3456 | ||
3457 | runtime = -cfs_rq->runtime_remaining + 1; | |
3458 | if (runtime > remaining) | |
3459 | runtime = remaining; | |
3460 | remaining -= runtime; | |
3461 | ||
3462 | cfs_rq->runtime_remaining += runtime; | |
3463 | cfs_rq->runtime_expires = expires; | |
3464 | ||
3465 | /* we check whether we're throttled above */ | |
3466 | if (cfs_rq->runtime_remaining > 0) | |
3467 | unthrottle_cfs_rq(cfs_rq); | |
3468 | ||
3469 | next: | |
3470 | raw_spin_unlock(&rq->lock); | |
3471 | ||
3472 | if (!remaining) | |
3473 | break; | |
3474 | } | |
3475 | rcu_read_unlock(); | |
3476 | ||
c06f04c7 | 3477 | return starting_runtime - remaining; |
671fd9da PT |
3478 | } |
3479 | ||
58088ad0 PT |
3480 | /* |
3481 | * Responsible for refilling a task_group's bandwidth and unthrottling its | |
3482 | * cfs_rqs as appropriate. If there has been no activity within the last | |
3483 | * period the timer is deactivated until scheduling resumes; cfs_b->idle is | |
3484 | * used to track this state. | |
3485 | */ | |
3486 | static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) | |
3487 | { | |
671fd9da | 3488 | u64 runtime, runtime_expires; |
51f2176d | 3489 | int throttled; |
58088ad0 | 3490 | |
58088ad0 PT |
3491 | /* no need to continue the timer with no bandwidth constraint */ |
3492 | if (cfs_b->quota == RUNTIME_INF) | |
51f2176d | 3493 | goto out_deactivate; |
58088ad0 | 3494 | |
671fd9da | 3495 | throttled = !list_empty(&cfs_b->throttled_cfs_rq); |
e8da1b18 | 3496 | cfs_b->nr_periods += overrun; |
671fd9da | 3497 | |
51f2176d BS |
3498 | /* |
3499 | * idle depends on !throttled (for the case of a large deficit), and if | |
3500 | * we're going inactive then everything else can be deferred | |
3501 | */ | |
3502 | if (cfs_b->idle && !throttled) | |
3503 | goto out_deactivate; | |
a9cf55b2 | 3504 | |
927b54fc BS |
3505 | /* |
3506 | * if we have relooped after returning idle once, we need to update our | |
3507 | * status as actually running, so that other cpus doing | |
3508 | * __start_cfs_bandwidth will stop trying to cancel us. | |
3509 | */ | |
3510 | cfs_b->timer_active = 1; | |
3511 | ||
a9cf55b2 PT |
3512 | __refill_cfs_bandwidth_runtime(cfs_b); |
3513 | ||
671fd9da PT |
3514 | if (!throttled) { |
3515 | /* mark as potentially idle for the upcoming period */ | |
3516 | cfs_b->idle = 1; | |
51f2176d | 3517 | return 0; |
671fd9da PT |
3518 | } |
3519 | ||
e8da1b18 NR |
3520 | /* account preceding periods in which throttling occurred */ |
3521 | cfs_b->nr_throttled += overrun; | |
3522 | ||
671fd9da | 3523 | runtime_expires = cfs_b->runtime_expires; |
671fd9da PT |
3524 | |
3525 | /* | |
c06f04c7 BS |
3526 | * This check is repeated as we are holding onto the new bandwidth while |
3527 | * we unthrottle. This can potentially race with an unthrottled group | |
3528 | * trying to acquire new bandwidth from the global pool. This can result | |
3529 | * in us over-using our runtime if it is all used during this loop, but | |
3530 | * only by limited amounts in that extreme case. | |
671fd9da | 3531 | */ |
c06f04c7 BS |
3532 | while (throttled && cfs_b->runtime > 0) { |
3533 | runtime = cfs_b->runtime; | |
671fd9da PT |
3534 | raw_spin_unlock(&cfs_b->lock); |
3535 | /* we can't nest cfs_b->lock while distributing bandwidth */ | |
3536 | runtime = distribute_cfs_runtime(cfs_b, runtime, | |
3537 | runtime_expires); | |
3538 | raw_spin_lock(&cfs_b->lock); | |
3539 | ||
3540 | throttled = !list_empty(&cfs_b->throttled_cfs_rq); | |
c06f04c7 BS |
3541 | |
3542 | cfs_b->runtime -= min(runtime, cfs_b->runtime); | |
671fd9da | 3543 | } |
58088ad0 | 3544 | |
671fd9da PT |
3545 | /* |
3546 | * While we are ensured activity in the period following an | |
3547 | * unthrottle, this also covers the case in which the new bandwidth is | |
3548 | * insufficient to cover the existing bandwidth deficit. (Forcing the | |
3549 | * timer to remain active while there are any throttled entities.) | |
3550 | */ | |
3551 | cfs_b->idle = 0; | |
58088ad0 | 3552 | |
51f2176d BS |
3553 | return 0; |
3554 | ||
3555 | out_deactivate: | |
3556 | cfs_b->timer_active = 0; | |
3557 | return 1; | |
58088ad0 | 3558 | } |
d3d9dc33 | 3559 | |
d8b4986d PT |
3560 | /* a cfs_rq won't donate quota below this amount */ |
3561 | static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC; | |
3562 | /* minimum remaining period time to redistribute slack quota */ | |
3563 | static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC; | |
3564 | /* how long we wait to gather additional slack before distributing */ | |
3565 | static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; | |
3566 | ||
db06e78c BS |
3567 | /* |
3568 | * Are we near the end of the current quota period? | |
3569 | * | |
3570 | * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the | |
3571 | * hrtimer base being cleared by __hrtimer_start_range_ns. In the case of | |
3572 | * migrate_hrtimers, base is never cleared, so we are fine. | |
3573 | */ | |
d8b4986d PT |
3574 | static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) |
3575 | { | |
3576 | struct hrtimer *refresh_timer = &cfs_b->period_timer; | |
3577 | u64 remaining; | |
3578 | ||
3579 | /* if the call-back is running a quota refresh is already occurring */ | |
3580 | if (hrtimer_callback_running(refresh_timer)) | |
3581 | return 1; | |
3582 | ||
3583 | /* is a quota refresh about to occur? */ | |
3584 | remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); | |
3585 | if (remaining < min_expire) | |
3586 | return 1; | |
3587 | ||
3588 | return 0; | |
3589 | } | |
3590 | ||
3591 | static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b) | |
3592 | { | |
3593 | u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration; | |
3594 | ||
3595 | /* if there's a quota refresh soon don't bother with slack */ | |
3596 | if (runtime_refresh_within(cfs_b, min_left)) | |
3597 | return; | |
3598 | ||
3599 | start_bandwidth_timer(&cfs_b->slack_timer, | |
3600 | ns_to_ktime(cfs_bandwidth_slack_period)); | |
3601 | } | |
3602 | ||
3603 | /* we know any runtime found here is valid as update_curr() precedes return */ | |
3604 | static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
3605 | { | |
3606 | struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); | |
3607 | s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime; | |
3608 | ||
3609 | if (slack_runtime <= 0) | |
3610 | return; | |
3611 | ||
3612 | raw_spin_lock(&cfs_b->lock); | |
3613 | if (cfs_b->quota != RUNTIME_INF && | |
3614 | cfs_rq->runtime_expires == cfs_b->runtime_expires) { | |
3615 | cfs_b->runtime += slack_runtime; | |
3616 | ||
3617 | /* we are under rq->lock, defer unthrottling using a timer */ | |
3618 | if (cfs_b->runtime > sched_cfs_bandwidth_slice() && | |
3619 | !list_empty(&cfs_b->throttled_cfs_rq)) | |
3620 | start_cfs_slack_bandwidth(cfs_b); | |
3621 | } | |
3622 | raw_spin_unlock(&cfs_b->lock); | |
3623 | ||
3624 | /* even if it's not valid for return we don't want to try again */ | |
3625 | cfs_rq->runtime_remaining -= slack_runtime; | |
3626 | } | |
3627 | ||
3628 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
3629 | { | |
56f570e5 PT |
3630 | if (!cfs_bandwidth_used()) |
3631 | return; | |
3632 | ||
fccfdc6f | 3633 | if (!cfs_rq->runtime_enabled || cfs_rq->nr_running) |
d8b4986d PT |
3634 | return; |
3635 | ||
3636 | __return_cfs_rq_runtime(cfs_rq); | |
3637 | } | |
3638 | ||
3639 | /* | |
3640 | * This is done with a timer (instead of inline with bandwidth return) since | |
3641 | * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs. | |
3642 | */ | |
3643 | static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) | |
3644 | { | |
3645 | u64 runtime = 0, slice = sched_cfs_bandwidth_slice(); | |
3646 | u64 expires; | |
3647 | ||
3648 | /* confirm we're still not at a refresh boundary */ | |
db06e78c BS |
3649 | raw_spin_lock(&cfs_b->lock); |
3650 | if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) { | |
3651 | raw_spin_unlock(&cfs_b->lock); | |
d8b4986d | 3652 | return; |
db06e78c | 3653 | } |
d8b4986d | 3654 | |
c06f04c7 | 3655 | if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) |
d8b4986d | 3656 | runtime = cfs_b->runtime; |
c06f04c7 | 3657 | |
d8b4986d PT |
3658 | expires = cfs_b->runtime_expires; |
3659 | raw_spin_unlock(&cfs_b->lock); | |
3660 | ||
3661 | if (!runtime) | |
3662 | return; | |
3663 | ||
3664 | runtime = distribute_cfs_runtime(cfs_b, runtime, expires); | |
3665 | ||
3666 | raw_spin_lock(&cfs_b->lock); | |
3667 | if (expires == cfs_b->runtime_expires) | |
c06f04c7 | 3668 | cfs_b->runtime -= min(runtime, cfs_b->runtime); |
d8b4986d PT |
3669 | raw_spin_unlock(&cfs_b->lock); |
3670 | } | |
3671 | ||
d3d9dc33 PT |
3672 | /* |
3673 | * When a group wakes up we want to make sure that its quota is not already | |
3674 | * expired/exceeded, otherwise it may be allowed to steal additional ticks of | |
3675 | * runtime as update_curr() throttling can not not trigger until it's on-rq. | |
3676 | */ | |
3677 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq) | |
3678 | { | |
56f570e5 PT |
3679 | if (!cfs_bandwidth_used()) |
3680 | return; | |
3681 | ||
d3d9dc33 PT |
3682 | /* an active group must be handled by the update_curr()->put() path */ |
3683 | if (!cfs_rq->runtime_enabled || cfs_rq->curr) | |
3684 | return; | |
3685 | ||
3686 | /* ensure the group is not already throttled */ | |
3687 | if (cfs_rq_throttled(cfs_rq)) | |
3688 | return; | |
3689 | ||
3690 | /* update runtime allocation */ | |
3691 | account_cfs_rq_runtime(cfs_rq, 0); | |
3692 | if (cfs_rq->runtime_remaining <= 0) | |
3693 | throttle_cfs_rq(cfs_rq); | |
3694 | } | |
3695 | ||
3696 | /* conditionally throttle active cfs_rq's from put_prev_entity() */ | |
678d5718 | 3697 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
d3d9dc33 | 3698 | { |
56f570e5 | 3699 | if (!cfs_bandwidth_used()) |
678d5718 | 3700 | return false; |
56f570e5 | 3701 | |
d3d9dc33 | 3702 | if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0)) |
678d5718 | 3703 | return false; |
d3d9dc33 PT |
3704 | |
3705 | /* | |
3706 | * it's possible for a throttled entity to be forced into a running | |
3707 | * state (e.g. set_curr_task), in this case we're finished. | |
3708 | */ | |
3709 | if (cfs_rq_throttled(cfs_rq)) | |
678d5718 | 3710 | return true; |
d3d9dc33 PT |
3711 | |
3712 | throttle_cfs_rq(cfs_rq); | |
678d5718 | 3713 | return true; |
d3d9dc33 | 3714 | } |
029632fb | 3715 | |
029632fb PZ |
3716 | static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) |
3717 | { | |
3718 | struct cfs_bandwidth *cfs_b = | |
3719 | container_of(timer, struct cfs_bandwidth, slack_timer); | |
3720 | do_sched_cfs_slack_timer(cfs_b); | |
3721 | ||
3722 | return HRTIMER_NORESTART; | |
3723 | } | |
3724 | ||
3725 | static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) | |
3726 | { | |
3727 | struct cfs_bandwidth *cfs_b = | |
3728 | container_of(timer, struct cfs_bandwidth, period_timer); | |
3729 | ktime_t now; | |
3730 | int overrun; | |
3731 | int idle = 0; | |
3732 | ||
51f2176d | 3733 | raw_spin_lock(&cfs_b->lock); |
029632fb PZ |
3734 | for (;;) { |
3735 | now = hrtimer_cb_get_time(timer); | |
3736 | overrun = hrtimer_forward(timer, now, cfs_b->period); | |
3737 | ||
3738 | if (!overrun) | |
3739 | break; | |
3740 | ||
3741 | idle = do_sched_cfs_period_timer(cfs_b, overrun); | |
3742 | } | |
51f2176d | 3743 | raw_spin_unlock(&cfs_b->lock); |
029632fb PZ |
3744 | |
3745 | return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; | |
3746 | } | |
3747 | ||
3748 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) | |
3749 | { | |
3750 | raw_spin_lock_init(&cfs_b->lock); | |
3751 | cfs_b->runtime = 0; | |
3752 | cfs_b->quota = RUNTIME_INF; | |
3753 | cfs_b->period = ns_to_ktime(default_cfs_period()); | |
3754 | ||
3755 | INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq); | |
3756 | hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
3757 | cfs_b->period_timer.function = sched_cfs_period_timer; | |
3758 | hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
3759 | cfs_b->slack_timer.function = sched_cfs_slack_timer; | |
3760 | } | |
3761 | ||
3762 | static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) | |
3763 | { | |
3764 | cfs_rq->runtime_enabled = 0; | |
3765 | INIT_LIST_HEAD(&cfs_rq->throttled_list); | |
3766 | } | |
3767 | ||
3768 | /* requires cfs_b->lock, may release to reprogram timer */ | |
09dc4ab0 | 3769 | void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b, bool force) |
029632fb PZ |
3770 | { |
3771 | /* | |
3772 | * The timer may be active because we're trying to set a new bandwidth | |
3773 | * period or because we're racing with the tear-down path | |
3774 | * (timer_active==0 becomes visible before the hrtimer call-back | |
3775 | * terminates). In either case we ensure that it's re-programmed | |
3776 | */ | |
927b54fc BS |
3777 | while (unlikely(hrtimer_active(&cfs_b->period_timer)) && |
3778 | hrtimer_try_to_cancel(&cfs_b->period_timer) < 0) { | |
3779 | /* bounce the lock to allow do_sched_cfs_period_timer to run */ | |
029632fb | 3780 | raw_spin_unlock(&cfs_b->lock); |
927b54fc | 3781 | cpu_relax(); |
029632fb PZ |
3782 | raw_spin_lock(&cfs_b->lock); |
3783 | /* if someone else restarted the timer then we're done */ | |
09dc4ab0 | 3784 | if (!force && cfs_b->timer_active) |
029632fb PZ |
3785 | return; |
3786 | } | |
3787 | ||
3788 | cfs_b->timer_active = 1; | |
3789 | start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period); | |
3790 | } | |
3791 | ||
3792 | static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) | |
3793 | { | |
3794 | hrtimer_cancel(&cfs_b->period_timer); | |
3795 | hrtimer_cancel(&cfs_b->slack_timer); | |
3796 | } | |
3797 | ||
0e59bdae KT |
3798 | static void __maybe_unused update_runtime_enabled(struct rq *rq) |
3799 | { | |
3800 | struct cfs_rq *cfs_rq; | |
3801 | ||
3802 | for_each_leaf_cfs_rq(rq, cfs_rq) { | |
3803 | struct cfs_bandwidth *cfs_b = &cfs_rq->tg->cfs_bandwidth; | |
3804 | ||
3805 | raw_spin_lock(&cfs_b->lock); | |
3806 | cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; | |
3807 | raw_spin_unlock(&cfs_b->lock); | |
3808 | } | |
3809 | } | |
3810 | ||
38dc3348 | 3811 | static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq) |
029632fb PZ |
3812 | { |
3813 | struct cfs_rq *cfs_rq; | |
3814 | ||
3815 | for_each_leaf_cfs_rq(rq, cfs_rq) { | |
029632fb PZ |
3816 | if (!cfs_rq->runtime_enabled) |
3817 | continue; | |
3818 | ||
3819 | /* | |
3820 | * clock_task is not advancing so we just need to make sure | |
3821 | * there's some valid quota amount | |
3822 | */ | |
51f2176d | 3823 | cfs_rq->runtime_remaining = 1; |
0e59bdae KT |
3824 | /* |
3825 | * Offline rq is schedulable till cpu is completely disabled | |
3826 | * in take_cpu_down(), so we prevent new cfs throttling here. | |
3827 | */ | |
3828 | cfs_rq->runtime_enabled = 0; | |
3829 | ||
029632fb PZ |
3830 | if (cfs_rq_throttled(cfs_rq)) |
3831 | unthrottle_cfs_rq(cfs_rq); | |
3832 | } | |
3833 | } | |
3834 | ||
3835 | #else /* CONFIG_CFS_BANDWIDTH */ | |
f1b17280 PT |
3836 | static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) |
3837 | { | |
78becc27 | 3838 | return rq_clock_task(rq_of(cfs_rq)); |
f1b17280 PT |
3839 | } |
3840 | ||
9dbdb155 | 3841 | static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {} |
678d5718 | 3842 | static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; } |
d3d9dc33 | 3843 | static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} |
6c16a6dc | 3844 | static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} |
85dac906 PT |
3845 | |
3846 | static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) | |
3847 | { | |
3848 | return 0; | |
3849 | } | |
64660c86 PT |
3850 | |
3851 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) | |
3852 | { | |
3853 | return 0; | |
3854 | } | |
3855 | ||
3856 | static inline int throttled_lb_pair(struct task_group *tg, | |
3857 | int src_cpu, int dest_cpu) | |
3858 | { | |
3859 | return 0; | |
3860 | } | |
029632fb PZ |
3861 | |
3862 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} | |
3863 | ||
3864 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
3865 | static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} | |
ab84d31e PT |
3866 | #endif |
3867 | ||
029632fb PZ |
3868 | static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
3869 | { | |
3870 | return NULL; | |
3871 | } | |
3872 | static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} | |
0e59bdae | 3873 | static inline void update_runtime_enabled(struct rq *rq) {} |
a4c96ae3 | 3874 | static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {} |
029632fb PZ |
3875 | |
3876 | #endif /* CONFIG_CFS_BANDWIDTH */ | |
3877 | ||
bf0f6f24 IM |
3878 | /************************************************** |
3879 | * CFS operations on tasks: | |
3880 | */ | |
3881 | ||
8f4d37ec PZ |
3882 | #ifdef CONFIG_SCHED_HRTICK |
3883 | static void hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
3884 | { | |
8f4d37ec PZ |
3885 | struct sched_entity *se = &p->se; |
3886 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
3887 | ||
3888 | WARN_ON(task_rq(p) != rq); | |
3889 | ||
b39e66ea | 3890 | if (cfs_rq->nr_running > 1) { |
8f4d37ec PZ |
3891 | u64 slice = sched_slice(cfs_rq, se); |
3892 | u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime; | |
3893 | s64 delta = slice - ran; | |
3894 | ||
3895 | if (delta < 0) { | |
3896 | if (rq->curr == p) | |
8875125e | 3897 | resched_curr(rq); |
8f4d37ec PZ |
3898 | return; |
3899 | } | |
3900 | ||
3901 | /* | |
3902 | * Don't schedule slices shorter than 10000ns, that just | |
3903 | * doesn't make sense. Rely on vruntime for fairness. | |
3904 | */ | |
31656519 | 3905 | if (rq->curr != p) |
157124c1 | 3906 | delta = max_t(s64, 10000LL, delta); |
8f4d37ec | 3907 | |
31656519 | 3908 | hrtick_start(rq, delta); |
8f4d37ec PZ |
3909 | } |
3910 | } | |
a4c2f00f PZ |
3911 | |
3912 | /* | |
3913 | * called from enqueue/dequeue and updates the hrtick when the | |
3914 | * current task is from our class and nr_running is low enough | |
3915 | * to matter. | |
3916 | */ | |
3917 | static void hrtick_update(struct rq *rq) | |
3918 | { | |
3919 | struct task_struct *curr = rq->curr; | |
3920 | ||
b39e66ea | 3921 | if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class) |
a4c2f00f PZ |
3922 | return; |
3923 | ||
3924 | if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency) | |
3925 | hrtick_start_fair(rq, curr); | |
3926 | } | |
55e12e5e | 3927 | #else /* !CONFIG_SCHED_HRTICK */ |
8f4d37ec PZ |
3928 | static inline void |
3929 | hrtick_start_fair(struct rq *rq, struct task_struct *p) | |
3930 | { | |
3931 | } | |
a4c2f00f PZ |
3932 | |
3933 | static inline void hrtick_update(struct rq *rq) | |
3934 | { | |
3935 | } | |
8f4d37ec PZ |
3936 | #endif |
3937 | ||
bf0f6f24 IM |
3938 | /* |
3939 | * The enqueue_task method is called before nr_running is | |
3940 | * increased. Here we update the fair scheduling stats and | |
3941 | * then put the task into the rbtree: | |
3942 | */ | |
ea87bb78 | 3943 | static void |
371fd7e7 | 3944 | enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
bf0f6f24 IM |
3945 | { |
3946 | struct cfs_rq *cfs_rq; | |
62fb1851 | 3947 | struct sched_entity *se = &p->se; |
bf0f6f24 IM |
3948 | |
3949 | for_each_sched_entity(se) { | |
62fb1851 | 3950 | if (se->on_rq) |
bf0f6f24 IM |
3951 | break; |
3952 | cfs_rq = cfs_rq_of(se); | |
88ec22d3 | 3953 | enqueue_entity(cfs_rq, se, flags); |
85dac906 PT |
3954 | |
3955 | /* | |
3956 | * end evaluation on encountering a throttled cfs_rq | |
3957 | * | |
3958 | * note: in the case of encountering a throttled cfs_rq we will | |
3959 | * post the final h_nr_running increment below. | |
3960 | */ | |
3961 | if (cfs_rq_throttled(cfs_rq)) | |
3962 | break; | |
953bfcd1 | 3963 | cfs_rq->h_nr_running++; |
85dac906 | 3964 | |
88ec22d3 | 3965 | flags = ENQUEUE_WAKEUP; |
bf0f6f24 | 3966 | } |
8f4d37ec | 3967 | |
2069dd75 | 3968 | for_each_sched_entity(se) { |
0f317143 | 3969 | cfs_rq = cfs_rq_of(se); |
953bfcd1 | 3970 | cfs_rq->h_nr_running++; |
2069dd75 | 3971 | |
85dac906 PT |
3972 | if (cfs_rq_throttled(cfs_rq)) |
3973 | break; | |
3974 | ||
17bc14b7 | 3975 | update_cfs_shares(cfs_rq); |
9ee474f5 | 3976 | update_entity_load_avg(se, 1); |
2069dd75 PZ |
3977 | } |
3978 | ||
18bf2805 BS |
3979 | if (!se) { |
3980 | update_rq_runnable_avg(rq, rq->nr_running); | |
72465447 | 3981 | add_nr_running(rq, 1); |
18bf2805 | 3982 | } |
a4c2f00f | 3983 | hrtick_update(rq); |
bf0f6f24 IM |
3984 | } |
3985 | ||
2f36825b VP |
3986 | static void set_next_buddy(struct sched_entity *se); |
3987 | ||
bf0f6f24 IM |
3988 | /* |
3989 | * The dequeue_task method is called before nr_running is | |
3990 | * decreased. We remove the task from the rbtree and | |
3991 | * update the fair scheduling stats: | |
3992 | */ | |
371fd7e7 | 3993 | static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
bf0f6f24 IM |
3994 | { |
3995 | struct cfs_rq *cfs_rq; | |
62fb1851 | 3996 | struct sched_entity *se = &p->se; |
2f36825b | 3997 | int task_sleep = flags & DEQUEUE_SLEEP; |
bf0f6f24 IM |
3998 | |
3999 | for_each_sched_entity(se) { | |
4000 | cfs_rq = cfs_rq_of(se); | |
371fd7e7 | 4001 | dequeue_entity(cfs_rq, se, flags); |
85dac906 PT |
4002 | |
4003 | /* | |
4004 | * end evaluation on encountering a throttled cfs_rq | |
4005 | * | |
4006 | * note: in the case of encountering a throttled cfs_rq we will | |
4007 | * post the final h_nr_running decrement below. | |
4008 | */ | |
4009 | if (cfs_rq_throttled(cfs_rq)) | |
4010 | break; | |
953bfcd1 | 4011 | cfs_rq->h_nr_running--; |
2069dd75 | 4012 | |
bf0f6f24 | 4013 | /* Don't dequeue parent if it has other entities besides us */ |
2f36825b VP |
4014 | if (cfs_rq->load.weight) { |
4015 | /* | |
4016 | * Bias pick_next to pick a task from this cfs_rq, as | |
4017 | * p is sleeping when it is within its sched_slice. | |
4018 | */ | |
4019 | if (task_sleep && parent_entity(se)) | |
4020 | set_next_buddy(parent_entity(se)); | |
9598c82d PT |
4021 | |
4022 | /* avoid re-evaluating load for this entity */ | |
4023 | se = parent_entity(se); | |
bf0f6f24 | 4024 | break; |
2f36825b | 4025 | } |
371fd7e7 | 4026 | flags |= DEQUEUE_SLEEP; |
bf0f6f24 | 4027 | } |
8f4d37ec | 4028 | |
2069dd75 | 4029 | for_each_sched_entity(se) { |
0f317143 | 4030 | cfs_rq = cfs_rq_of(se); |
953bfcd1 | 4031 | cfs_rq->h_nr_running--; |
2069dd75 | 4032 | |
85dac906 PT |
4033 | if (cfs_rq_throttled(cfs_rq)) |
4034 | break; | |
4035 | ||
17bc14b7 | 4036 | update_cfs_shares(cfs_rq); |
9ee474f5 | 4037 | update_entity_load_avg(se, 1); |
2069dd75 PZ |
4038 | } |
4039 | ||
18bf2805 | 4040 | if (!se) { |
72465447 | 4041 | sub_nr_running(rq, 1); |
18bf2805 BS |
4042 | update_rq_runnable_avg(rq, 1); |
4043 | } | |
a4c2f00f | 4044 | hrtick_update(rq); |
bf0f6f24 IM |
4045 | } |
4046 | ||
e7693a36 | 4047 | #ifdef CONFIG_SMP |
029632fb PZ |
4048 | /* Used instead of source_load when we know the type == 0 */ |
4049 | static unsigned long weighted_cpuload(const int cpu) | |
4050 | { | |
b92486cb | 4051 | return cpu_rq(cpu)->cfs.runnable_load_avg; |
029632fb PZ |
4052 | } |
4053 | ||
4054 | /* | |
4055 | * Return a low guess at the load of a migration-source cpu weighted | |
4056 | * according to the scheduling class and "nice" value. | |
4057 | * | |
4058 | * We want to under-estimate the load of migration sources, to | |
4059 | * balance conservatively. | |
4060 | */ | |
4061 | static unsigned long source_load(int cpu, int type) | |
4062 | { | |
4063 | struct rq *rq = cpu_rq(cpu); | |
4064 | unsigned long total = weighted_cpuload(cpu); | |
4065 | ||
4066 | if (type == 0 || !sched_feat(LB_BIAS)) | |
4067 | return total; | |
4068 | ||
4069 | return min(rq->cpu_load[type-1], total); | |
4070 | } | |
4071 | ||
4072 | /* | |
4073 | * Return a high guess at the load of a migration-target cpu weighted | |
4074 | * according to the scheduling class and "nice" value. | |
4075 | */ | |
4076 | static unsigned long target_load(int cpu, int type) | |
4077 | { | |
4078 | struct rq *rq = cpu_rq(cpu); | |
4079 | unsigned long total = weighted_cpuload(cpu); | |
4080 | ||
4081 | if (type == 0 || !sched_feat(LB_BIAS)) | |
4082 | return total; | |
4083 | ||
4084 | return max(rq->cpu_load[type-1], total); | |
4085 | } | |
4086 | ||
ced549fa | 4087 | static unsigned long capacity_of(int cpu) |
029632fb | 4088 | { |
ced549fa | 4089 | return cpu_rq(cpu)->cpu_capacity; |
029632fb PZ |
4090 | } |
4091 | ||
4092 | static unsigned long cpu_avg_load_per_task(int cpu) | |
4093 | { | |
4094 | struct rq *rq = cpu_rq(cpu); | |
4095 | unsigned long nr_running = ACCESS_ONCE(rq->nr_running); | |
b92486cb | 4096 | unsigned long load_avg = rq->cfs.runnable_load_avg; |
029632fb PZ |
4097 | |
4098 | if (nr_running) | |
b92486cb | 4099 | return load_avg / nr_running; |
029632fb PZ |
4100 | |
4101 | return 0; | |
4102 | } | |
4103 | ||
62470419 MW |
4104 | static void record_wakee(struct task_struct *p) |
4105 | { | |
4106 | /* | |
4107 | * Rough decay (wiping) for cost saving, don't worry | |
4108 | * about the boundary, really active task won't care | |
4109 | * about the loss. | |
4110 | */ | |
2538d960 | 4111 | if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) { |
096aa338 | 4112 | current->wakee_flips >>= 1; |
62470419 MW |
4113 | current->wakee_flip_decay_ts = jiffies; |
4114 | } | |
4115 | ||
4116 | if (current->last_wakee != p) { | |
4117 | current->last_wakee = p; | |
4118 | current->wakee_flips++; | |
4119 | } | |
4120 | } | |
098fb9db | 4121 | |
74f8e4b2 | 4122 | static void task_waking_fair(struct task_struct *p) |
88ec22d3 PZ |
4123 | { |
4124 | struct sched_entity *se = &p->se; | |
4125 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
3fe1698b PZ |
4126 | u64 min_vruntime; |
4127 | ||
4128 | #ifndef CONFIG_64BIT | |
4129 | u64 min_vruntime_copy; | |
88ec22d3 | 4130 | |
3fe1698b PZ |
4131 | do { |
4132 | min_vruntime_copy = cfs_rq->min_vruntime_copy; | |
4133 | smp_rmb(); | |
4134 | min_vruntime = cfs_rq->min_vruntime; | |
4135 | } while (min_vruntime != min_vruntime_copy); | |
4136 | #else | |
4137 | min_vruntime = cfs_rq->min_vruntime; | |
4138 | #endif | |
88ec22d3 | 4139 | |
3fe1698b | 4140 | se->vruntime -= min_vruntime; |
62470419 | 4141 | record_wakee(p); |
88ec22d3 PZ |
4142 | } |
4143 | ||
bb3469ac | 4144 | #ifdef CONFIG_FAIR_GROUP_SCHED |
f5bfb7d9 PZ |
4145 | /* |
4146 | * effective_load() calculates the load change as seen from the root_task_group | |
4147 | * | |
4148 | * Adding load to a group doesn't make a group heavier, but can cause movement | |
4149 | * of group shares between cpus. Assuming the shares were perfectly aligned one | |
4150 | * can calculate the shift in shares. | |
cf5f0acf PZ |
4151 | * |
4152 | * Calculate the effective load difference if @wl is added (subtracted) to @tg | |
4153 | * on this @cpu and results in a total addition (subtraction) of @wg to the | |
4154 | * total group weight. | |
4155 | * | |
4156 | * Given a runqueue weight distribution (rw_i) we can compute a shares | |
4157 | * distribution (s_i) using: | |
4158 | * | |
4159 | * s_i = rw_i / \Sum rw_j (1) | |
4160 | * | |
4161 | * Suppose we have 4 CPUs and our @tg is a direct child of the root group and | |
4162 | * has 7 equal weight tasks, distributed as below (rw_i), with the resulting | |
4163 | * shares distribution (s_i): | |
4164 | * | |
4165 | * rw_i = { 2, 4, 1, 0 } | |
4166 | * s_i = { 2/7, 4/7, 1/7, 0 } | |
4167 | * | |
4168 | * As per wake_affine() we're interested in the load of two CPUs (the CPU the | |
4169 | * task used to run on and the CPU the waker is running on), we need to | |
4170 | * compute the effect of waking a task on either CPU and, in case of a sync | |
4171 | * wakeup, compute the effect of the current task going to sleep. | |
4172 | * | |
4173 | * So for a change of @wl to the local @cpu with an overall group weight change | |
4174 | * of @wl we can compute the new shares distribution (s'_i) using: | |
4175 | * | |
4176 | * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2) | |
4177 | * | |
4178 | * Suppose we're interested in CPUs 0 and 1, and want to compute the load | |
4179 | * differences in waking a task to CPU 0. The additional task changes the | |
4180 | * weight and shares distributions like: | |
4181 | * | |
4182 | * rw'_i = { 3, 4, 1, 0 } | |
4183 | * s'_i = { 3/8, 4/8, 1/8, 0 } | |
4184 | * | |
4185 | * We can then compute the difference in effective weight by using: | |
4186 | * | |
4187 | * dw_i = S * (s'_i - s_i) (3) | |
4188 | * | |
4189 | * Where 'S' is the group weight as seen by its parent. | |
4190 | * | |
4191 | * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7) | |
4192 | * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 - | |
4193 | * 4/7) times the weight of the group. | |
f5bfb7d9 | 4194 | */ |
2069dd75 | 4195 | static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
bb3469ac | 4196 | { |
4be9daaa | 4197 | struct sched_entity *se = tg->se[cpu]; |
f1d239f7 | 4198 | |
9722c2da | 4199 | if (!tg->parent) /* the trivial, non-cgroup case */ |
f1d239f7 PZ |
4200 | return wl; |
4201 | ||
4be9daaa | 4202 | for_each_sched_entity(se) { |
cf5f0acf | 4203 | long w, W; |
4be9daaa | 4204 | |
977dda7c | 4205 | tg = se->my_q->tg; |
bb3469ac | 4206 | |
cf5f0acf PZ |
4207 | /* |
4208 | * W = @wg + \Sum rw_j | |
4209 | */ | |
4210 | W = wg + calc_tg_weight(tg, se->my_q); | |
4be9daaa | 4211 | |
cf5f0acf PZ |
4212 | /* |
4213 | * w = rw_i + @wl | |
4214 | */ | |
4215 | w = se->my_q->load.weight + wl; | |
940959e9 | 4216 | |
cf5f0acf PZ |
4217 | /* |
4218 | * wl = S * s'_i; see (2) | |
4219 | */ | |
4220 | if (W > 0 && w < W) | |
4221 | wl = (w * tg->shares) / W; | |
977dda7c PT |
4222 | else |
4223 | wl = tg->shares; | |
940959e9 | 4224 | |
cf5f0acf PZ |
4225 | /* |
4226 | * Per the above, wl is the new se->load.weight value; since | |
4227 | * those are clipped to [MIN_SHARES, ...) do so now. See | |
4228 | * calc_cfs_shares(). | |
4229 | */ | |
977dda7c PT |
4230 | if (wl < MIN_SHARES) |
4231 | wl = MIN_SHARES; | |
cf5f0acf PZ |
4232 | |
4233 | /* | |
4234 | * wl = dw_i = S * (s'_i - s_i); see (3) | |
4235 | */ | |
977dda7c | 4236 | wl -= se->load.weight; |
cf5f0acf PZ |
4237 | |
4238 | /* | |
4239 | * Recursively apply this logic to all parent groups to compute | |
4240 | * the final effective load change on the root group. Since | |
4241 | * only the @tg group gets extra weight, all parent groups can | |
4242 | * only redistribute existing shares. @wl is the shift in shares | |
4243 | * resulting from this level per the above. | |
4244 | */ | |
4be9daaa | 4245 | wg = 0; |
4be9daaa | 4246 | } |
bb3469ac | 4247 | |
4be9daaa | 4248 | return wl; |
bb3469ac PZ |
4249 | } |
4250 | #else | |
4be9daaa | 4251 | |
58d081b5 | 4252 | static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
4be9daaa | 4253 | { |
83378269 | 4254 | return wl; |
bb3469ac | 4255 | } |
4be9daaa | 4256 | |
bb3469ac PZ |
4257 | #endif |
4258 | ||
62470419 MW |
4259 | static int wake_wide(struct task_struct *p) |
4260 | { | |
7d9ffa89 | 4261 | int factor = this_cpu_read(sd_llc_size); |
62470419 MW |
4262 | |
4263 | /* | |
4264 | * Yeah, it's the switching-frequency, could means many wakee or | |
4265 | * rapidly switch, use factor here will just help to automatically | |
4266 | * adjust the loose-degree, so bigger node will lead to more pull. | |
4267 | */ | |
4268 | if (p->wakee_flips > factor) { | |
4269 | /* | |
4270 | * wakee is somewhat hot, it needs certain amount of cpu | |
4271 | * resource, so if waker is far more hot, prefer to leave | |
4272 | * it alone. | |
4273 | */ | |
4274 | if (current->wakee_flips > (factor * p->wakee_flips)) | |
4275 | return 1; | |
4276 | } | |
4277 | ||
4278 | return 0; | |
4279 | } | |
4280 | ||
c88d5910 | 4281 | static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) |
098fb9db | 4282 | { |
e37b6a7b | 4283 | s64 this_load, load; |
c88d5910 | 4284 | int idx, this_cpu, prev_cpu; |
098fb9db | 4285 | unsigned long tl_per_task; |
c88d5910 | 4286 | struct task_group *tg; |
83378269 | 4287 | unsigned long weight; |
b3137bc8 | 4288 | int balanced; |
098fb9db | 4289 | |
62470419 MW |
4290 | /* |
4291 | * If we wake multiple tasks be careful to not bounce | |
4292 | * ourselves around too much. | |
4293 | */ | |
4294 | if (wake_wide(p)) | |
4295 | return 0; | |
4296 | ||
c88d5910 PZ |
4297 | idx = sd->wake_idx; |
4298 | this_cpu = smp_processor_id(); | |
4299 | prev_cpu = task_cpu(p); | |
4300 | load = source_load(prev_cpu, idx); | |
4301 | this_load = target_load(this_cpu, idx); | |
098fb9db | 4302 | |
b3137bc8 MG |
4303 | /* |
4304 | * If sync wakeup then subtract the (maximum possible) | |
4305 | * effect of the currently running task from the load | |
4306 | * of the current CPU: | |
4307 | */ | |
83378269 PZ |
4308 | if (sync) { |
4309 | tg = task_group(current); | |
4310 | weight = current->se.load.weight; | |
4311 | ||
c88d5910 | 4312 | this_load += effective_load(tg, this_cpu, -weight, -weight); |
83378269 PZ |
4313 | load += effective_load(tg, prev_cpu, 0, -weight); |
4314 | } | |
b3137bc8 | 4315 | |
83378269 PZ |
4316 | tg = task_group(p); |
4317 | weight = p->se.load.weight; | |
b3137bc8 | 4318 | |
71a29aa7 PZ |
4319 | /* |
4320 | * In low-load situations, where prev_cpu is idle and this_cpu is idle | |
c88d5910 PZ |
4321 | * due to the sync cause above having dropped this_load to 0, we'll |
4322 | * always have an imbalance, but there's really nothing you can do | |
4323 | * about that, so that's good too. | |
71a29aa7 PZ |
4324 | * |
4325 | * Otherwise check if either cpus are near enough in load to allow this | |
4326 | * task to be woken on this_cpu. | |
4327 | */ | |
e37b6a7b PT |
4328 | if (this_load > 0) { |
4329 | s64 this_eff_load, prev_eff_load; | |
e51fd5e2 PZ |
4330 | |
4331 | this_eff_load = 100; | |
ced549fa | 4332 | this_eff_load *= capacity_of(prev_cpu); |
e51fd5e2 PZ |
4333 | this_eff_load *= this_load + |
4334 | effective_load(tg, this_cpu, weight, weight); | |
4335 | ||
4336 | prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2; | |
ced549fa | 4337 | prev_eff_load *= capacity_of(this_cpu); |
e51fd5e2 PZ |
4338 | prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight); |
4339 | ||
4340 | balanced = this_eff_load <= prev_eff_load; | |
4341 | } else | |
4342 | balanced = true; | |
b3137bc8 | 4343 | |
098fb9db | 4344 | /* |
4ae7d5ce IM |
4345 | * If the currently running task will sleep within |
4346 | * a reasonable amount of time then attract this newly | |
4347 | * woken task: | |
098fb9db | 4348 | */ |
2fb7635c PZ |
4349 | if (sync && balanced) |
4350 | return 1; | |
098fb9db | 4351 | |
41acab88 | 4352 | schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts); |
098fb9db IM |
4353 | tl_per_task = cpu_avg_load_per_task(this_cpu); |
4354 | ||
c88d5910 PZ |
4355 | if (balanced || |
4356 | (this_load <= load && | |
4357 | this_load + target_load(prev_cpu, idx) <= tl_per_task)) { | |
098fb9db IM |
4358 | /* |
4359 | * This domain has SD_WAKE_AFFINE and | |
4360 | * p is cache cold in this domain, and | |
4361 | * there is no bad imbalance. | |
4362 | */ | |
c88d5910 | 4363 | schedstat_inc(sd, ttwu_move_affine); |
41acab88 | 4364 | schedstat_inc(p, se.statistics.nr_wakeups_affine); |
098fb9db IM |
4365 | |
4366 | return 1; | |
4367 | } | |
4368 | return 0; | |
4369 | } | |
4370 | ||
aaee1203 PZ |
4371 | /* |
4372 | * find_idlest_group finds and returns the least busy CPU group within the | |
4373 | * domain. | |
4374 | */ | |
4375 | static struct sched_group * | |
78e7ed53 | 4376 | find_idlest_group(struct sched_domain *sd, struct task_struct *p, |
c44f2a02 | 4377 | int this_cpu, int sd_flag) |
e7693a36 | 4378 | { |
b3bd3de6 | 4379 | struct sched_group *idlest = NULL, *group = sd->groups; |
aaee1203 | 4380 | unsigned long min_load = ULONG_MAX, this_load = 0; |
c44f2a02 | 4381 | int load_idx = sd->forkexec_idx; |
aaee1203 | 4382 | int imbalance = 100 + (sd->imbalance_pct-100)/2; |
e7693a36 | 4383 | |
c44f2a02 VG |
4384 | if (sd_flag & SD_BALANCE_WAKE) |
4385 | load_idx = sd->wake_idx; | |
4386 | ||
aaee1203 PZ |
4387 | do { |
4388 | unsigned long load, avg_load; | |
4389 | int local_group; | |
4390 | int i; | |
e7693a36 | 4391 | |
aaee1203 PZ |
4392 | /* Skip over this group if it has no CPUs allowed */ |
4393 | if (!cpumask_intersects(sched_group_cpus(group), | |
fa17b507 | 4394 | tsk_cpus_allowed(p))) |
aaee1203 PZ |
4395 | continue; |
4396 | ||
4397 | local_group = cpumask_test_cpu(this_cpu, | |
4398 | sched_group_cpus(group)); | |
4399 | ||
4400 | /* Tally up the load of all CPUs in the group */ | |
4401 | avg_load = 0; | |
4402 | ||
4403 | for_each_cpu(i, sched_group_cpus(group)) { | |
4404 | /* Bias balancing toward cpus of our domain */ | |
4405 | if (local_group) | |
4406 | load = source_load(i, load_idx); | |
4407 | else | |
4408 | load = target_load(i, load_idx); | |
4409 | ||
4410 | avg_load += load; | |
4411 | } | |
4412 | ||
63b2ca30 | 4413 | /* Adjust by relative CPU capacity of the group */ |
ca8ce3d0 | 4414 | avg_load = (avg_load * SCHED_CAPACITY_SCALE) / group->sgc->capacity; |
aaee1203 PZ |
4415 | |
4416 | if (local_group) { | |
4417 | this_load = avg_load; | |
aaee1203 PZ |
4418 | } else if (avg_load < min_load) { |
4419 | min_load = avg_load; | |
4420 | idlest = group; | |
4421 | } | |
4422 | } while (group = group->next, group != sd->groups); | |
4423 | ||
4424 | if (!idlest || 100*this_load < imbalance*min_load) | |
4425 | return NULL; | |
4426 | return idlest; | |
4427 | } | |
4428 | ||
4429 | /* | |
4430 | * find_idlest_cpu - find the idlest cpu among the cpus in group. | |
4431 | */ | |
4432 | static int | |
4433 | find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) | |
4434 | { | |
4435 | unsigned long load, min_load = ULONG_MAX; | |
4436 | int idlest = -1; | |
4437 | int i; | |
4438 | ||
4439 | /* Traverse only the allowed CPUs */ | |
fa17b507 | 4440 | for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { |
aaee1203 PZ |
4441 | load = weighted_cpuload(i); |
4442 | ||
4443 | if (load < min_load || (load == min_load && i == this_cpu)) { | |
4444 | min_load = load; | |
4445 | idlest = i; | |
e7693a36 GH |
4446 | } |
4447 | } | |
4448 | ||
aaee1203 PZ |
4449 | return idlest; |
4450 | } | |
e7693a36 | 4451 | |
a50bde51 PZ |
4452 | /* |
4453 | * Try and locate an idle CPU in the sched_domain. | |
4454 | */ | |
99bd5e2f | 4455 | static int select_idle_sibling(struct task_struct *p, int target) |
a50bde51 | 4456 | { |
99bd5e2f | 4457 | struct sched_domain *sd; |
37407ea7 | 4458 | struct sched_group *sg; |
e0a79f52 | 4459 | int i = task_cpu(p); |
a50bde51 | 4460 | |
e0a79f52 MG |
4461 | if (idle_cpu(target)) |
4462 | return target; | |
99bd5e2f SS |
4463 | |
4464 | /* | |
e0a79f52 | 4465 | * If the prevous cpu is cache affine and idle, don't be stupid. |
99bd5e2f | 4466 | */ |
e0a79f52 MG |
4467 | if (i != target && cpus_share_cache(i, target) && idle_cpu(i)) |
4468 | return i; | |
a50bde51 PZ |
4469 | |
4470 | /* | |
37407ea7 | 4471 | * Otherwise, iterate the domains and find an elegible idle cpu. |
a50bde51 | 4472 | */ |
518cd623 | 4473 | sd = rcu_dereference(per_cpu(sd_llc, target)); |
970e1789 | 4474 | for_each_lower_domain(sd) { |
37407ea7 LT |
4475 | sg = sd->groups; |
4476 | do { | |
4477 | if (!cpumask_intersects(sched_group_cpus(sg), | |
4478 | tsk_cpus_allowed(p))) | |
4479 | goto next; | |
4480 | ||
4481 | for_each_cpu(i, sched_group_cpus(sg)) { | |
e0a79f52 | 4482 | if (i == target || !idle_cpu(i)) |
37407ea7 LT |
4483 | goto next; |
4484 | } | |
970e1789 | 4485 | |
37407ea7 LT |
4486 | target = cpumask_first_and(sched_group_cpus(sg), |
4487 | tsk_cpus_allowed(p)); | |
4488 | goto done; | |
4489 | next: | |
4490 | sg = sg->next; | |
4491 | } while (sg != sd->groups); | |
4492 | } | |
4493 | done: | |
a50bde51 PZ |
4494 | return target; |
4495 | } | |
4496 | ||
aaee1203 | 4497 | /* |
de91b9cb MR |
4498 | * select_task_rq_fair: Select target runqueue for the waking task in domains |
4499 | * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE, | |
4500 | * SD_BALANCE_FORK, or SD_BALANCE_EXEC. | |
aaee1203 | 4501 | * |
de91b9cb MR |
4502 | * Balances load by selecting the idlest cpu in the idlest group, or under |
4503 | * certain conditions an idle sibling cpu if the domain has SD_WAKE_AFFINE set. | |
aaee1203 | 4504 | * |
de91b9cb | 4505 | * Returns the target cpu number. |
aaee1203 PZ |
4506 | * |
4507 | * preempt must be disabled. | |
4508 | */ | |
0017d735 | 4509 | static int |
ac66f547 | 4510 | select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags) |
aaee1203 | 4511 | { |
29cd8bae | 4512 | struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; |
c88d5910 | 4513 | int cpu = smp_processor_id(); |
c88d5910 | 4514 | int new_cpu = cpu; |
99bd5e2f | 4515 | int want_affine = 0; |
5158f4e4 | 4516 | int sync = wake_flags & WF_SYNC; |
c88d5910 | 4517 | |
29baa747 | 4518 | if (p->nr_cpus_allowed == 1) |
76854c7e MG |
4519 | return prev_cpu; |
4520 | ||
0763a660 | 4521 | if (sd_flag & SD_BALANCE_WAKE) { |
fa17b507 | 4522 | if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) |
c88d5910 PZ |
4523 | want_affine = 1; |
4524 | new_cpu = prev_cpu; | |
4525 | } | |
aaee1203 | 4526 | |
dce840a0 | 4527 | rcu_read_lock(); |
aaee1203 | 4528 | for_each_domain(cpu, tmp) { |
e4f42888 PZ |
4529 | if (!(tmp->flags & SD_LOAD_BALANCE)) |
4530 | continue; | |
4531 | ||
fe3bcfe1 | 4532 | /* |
99bd5e2f SS |
4533 | * If both cpu and prev_cpu are part of this domain, |
4534 | * cpu is a valid SD_WAKE_AFFINE target. | |
fe3bcfe1 | 4535 | */ |
99bd5e2f SS |
4536 | if (want_affine && (tmp->flags & SD_WAKE_AFFINE) && |
4537 | cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) { | |
4538 | affine_sd = tmp; | |
29cd8bae | 4539 | break; |
f03542a7 | 4540 | } |
29cd8bae | 4541 | |
f03542a7 | 4542 | if (tmp->flags & sd_flag) |
29cd8bae PZ |
4543 | sd = tmp; |
4544 | } | |
4545 | ||
8bf21433 RR |
4546 | if (affine_sd && cpu != prev_cpu && wake_affine(affine_sd, p, sync)) |
4547 | prev_cpu = cpu; | |
dce840a0 | 4548 | |
8bf21433 | 4549 | if (sd_flag & SD_BALANCE_WAKE) { |
dce840a0 PZ |
4550 | new_cpu = select_idle_sibling(p, prev_cpu); |
4551 | goto unlock; | |
8b911acd | 4552 | } |
e7693a36 | 4553 | |
aaee1203 PZ |
4554 | while (sd) { |
4555 | struct sched_group *group; | |
c88d5910 | 4556 | int weight; |
098fb9db | 4557 | |
0763a660 | 4558 | if (!(sd->flags & sd_flag)) { |
aaee1203 PZ |
4559 | sd = sd->child; |
4560 | continue; | |
4561 | } | |
098fb9db | 4562 | |
c44f2a02 | 4563 | group = find_idlest_group(sd, p, cpu, sd_flag); |
aaee1203 PZ |
4564 | if (!group) { |
4565 | sd = sd->child; | |
4566 | continue; | |
4567 | } | |
4ae7d5ce | 4568 | |
d7c33c49 | 4569 | new_cpu = find_idlest_cpu(group, p, cpu); |
aaee1203 PZ |
4570 | if (new_cpu == -1 || new_cpu == cpu) { |
4571 | /* Now try balancing at a lower domain level of cpu */ | |
4572 | sd = sd->child; | |
4573 | continue; | |
e7693a36 | 4574 | } |
aaee1203 PZ |
4575 | |
4576 | /* Now try balancing at a lower domain level of new_cpu */ | |
4577 | cpu = new_cpu; | |
669c55e9 | 4578 | weight = sd->span_weight; |
aaee1203 PZ |
4579 | sd = NULL; |
4580 | for_each_domain(cpu, tmp) { | |
669c55e9 | 4581 | if (weight <= tmp->span_weight) |
aaee1203 | 4582 | break; |
0763a660 | 4583 | if (tmp->flags & sd_flag) |
aaee1203 PZ |
4584 | sd = tmp; |
4585 | } | |
4586 | /* while loop will break here if sd == NULL */ | |
e7693a36 | 4587 | } |
dce840a0 PZ |
4588 | unlock: |
4589 | rcu_read_unlock(); | |
e7693a36 | 4590 | |
c88d5910 | 4591 | return new_cpu; |
e7693a36 | 4592 | } |
0a74bef8 PT |
4593 | |
4594 | /* | |
4595 | * Called immediately before a task is migrated to a new cpu; task_cpu(p) and | |
4596 | * cfs_rq_of(p) references at time of call are still valid and identify the | |
4597 | * previous cpu. However, the caller only guarantees p->pi_lock is held; no | |
4598 | * other assumptions, including the state of rq->lock, should be made. | |
4599 | */ | |
4600 | static void | |
4601 | migrate_task_rq_fair(struct task_struct *p, int next_cpu) | |
4602 | { | |
aff3e498 PT |
4603 | struct sched_entity *se = &p->se; |
4604 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
4605 | ||
4606 | /* | |
4607 | * Load tracking: accumulate removed load so that it can be processed | |
4608 | * when we next update owning cfs_rq under rq->lock. Tasks contribute | |
4609 | * to blocked load iff they have a positive decay-count. It can never | |
4610 | * be negative here since on-rq tasks have decay-count == 0. | |
4611 | */ | |
4612 | if (se->avg.decay_count) { | |
4613 | se->avg.decay_count = -__synchronize_entity_decay(se); | |
2509940f AS |
4614 | atomic_long_add(se->avg.load_avg_contrib, |
4615 | &cfs_rq->removed_load); | |
aff3e498 | 4616 | } |
3944a927 BS |
4617 | |
4618 | /* We have migrated, no longer consider this task hot */ | |
4619 | se->exec_start = 0; | |
0a74bef8 | 4620 | } |
e7693a36 GH |
4621 | #endif /* CONFIG_SMP */ |
4622 | ||
e52fb7c0 PZ |
4623 | static unsigned long |
4624 | wakeup_gran(struct sched_entity *curr, struct sched_entity *se) | |
0bbd3336 PZ |
4625 | { |
4626 | unsigned long gran = sysctl_sched_wakeup_granularity; | |
4627 | ||
4628 | /* | |
e52fb7c0 PZ |
4629 | * Since its curr running now, convert the gran from real-time |
4630 | * to virtual-time in his units. | |
13814d42 MG |
4631 | * |
4632 | * By using 'se' instead of 'curr' we penalize light tasks, so | |
4633 | * they get preempted easier. That is, if 'se' < 'curr' then | |
4634 | * the resulting gran will be larger, therefore penalizing the | |
4635 | * lighter, if otoh 'se' > 'curr' then the resulting gran will | |
4636 | * be smaller, again penalizing the lighter task. | |
4637 | * | |
4638 | * This is especially important for buddies when the leftmost | |
4639 | * task is higher priority than the buddy. | |
0bbd3336 | 4640 | */ |
f4ad9bd2 | 4641 | return calc_delta_fair(gran, se); |
0bbd3336 PZ |
4642 | } |
4643 | ||
464b7527 PZ |
4644 | /* |
4645 | * Should 'se' preempt 'curr'. | |
4646 | * | |
4647 | * |s1 | |
4648 | * |s2 | |
4649 | * |s3 | |
4650 | * g | |
4651 | * |<--->|c | |
4652 | * | |
4653 | * w(c, s1) = -1 | |
4654 | * w(c, s2) = 0 | |
4655 | * w(c, s3) = 1 | |
4656 | * | |
4657 | */ | |
4658 | static int | |
4659 | wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) | |
4660 | { | |
4661 | s64 gran, vdiff = curr->vruntime - se->vruntime; | |
4662 | ||
4663 | if (vdiff <= 0) | |
4664 | return -1; | |
4665 | ||
e52fb7c0 | 4666 | gran = wakeup_gran(curr, se); |
464b7527 PZ |
4667 | if (vdiff > gran) |
4668 | return 1; | |
4669 | ||
4670 | return 0; | |
4671 | } | |
4672 | ||
02479099 PZ |
4673 | static void set_last_buddy(struct sched_entity *se) |
4674 | { | |
69c80f3e VP |
4675 | if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
4676 | return; | |
4677 | ||
4678 | for_each_sched_entity(se) | |
4679 | cfs_rq_of(se)->last = se; | |
02479099 PZ |
4680 | } |
4681 | ||
4682 | static void set_next_buddy(struct sched_entity *se) | |
4683 | { | |
69c80f3e VP |
4684 | if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
4685 | return; | |
4686 | ||
4687 | for_each_sched_entity(se) | |
4688 | cfs_rq_of(se)->next = se; | |
02479099 PZ |
4689 | } |
4690 | ||
ac53db59 RR |
4691 | static void set_skip_buddy(struct sched_entity *se) |
4692 | { | |
69c80f3e VP |
4693 | for_each_sched_entity(se) |
4694 | cfs_rq_of(se)->skip = se; | |
ac53db59 RR |
4695 | } |
4696 | ||
bf0f6f24 IM |
4697 | /* |
4698 | * Preempt the current task with a newly woken task if needed: | |
4699 | */ | |
5a9b86f6 | 4700 | static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) |
bf0f6f24 IM |
4701 | { |
4702 | struct task_struct *curr = rq->curr; | |
8651a86c | 4703 | struct sched_entity *se = &curr->se, *pse = &p->se; |
03e89e45 | 4704 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
f685ceac | 4705 | int scale = cfs_rq->nr_running >= sched_nr_latency; |
2f36825b | 4706 | int next_buddy_marked = 0; |
bf0f6f24 | 4707 | |
4ae7d5ce IM |
4708 | if (unlikely(se == pse)) |
4709 | return; | |
4710 | ||
5238cdd3 | 4711 | /* |
163122b7 | 4712 | * This is possible from callers such as attach_tasks(), in which we |
5238cdd3 PT |
4713 | * unconditionally check_prempt_curr() after an enqueue (which may have |
4714 | * lead to a throttle). This both saves work and prevents false | |
4715 | * next-buddy nomination below. | |
4716 | */ | |
4717 | if (unlikely(throttled_hierarchy(cfs_rq_of(pse)))) | |
4718 | return; | |
4719 | ||
2f36825b | 4720 | if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) { |
3cb63d52 | 4721 | set_next_buddy(pse); |
2f36825b VP |
4722 | next_buddy_marked = 1; |
4723 | } | |
57fdc26d | 4724 | |
aec0a514 BR |
4725 | /* |
4726 | * We can come here with TIF_NEED_RESCHED already set from new task | |
4727 | * wake up path. | |
5238cdd3 PT |
4728 | * |
4729 | * Note: this also catches the edge-case of curr being in a throttled | |
4730 | * group (e.g. via set_curr_task), since update_curr() (in the | |
4731 | * enqueue of curr) will have resulted in resched being set. This | |
4732 | * prevents us from potentially nominating it as a false LAST_BUDDY | |
4733 | * below. | |
aec0a514 BR |
4734 | */ |
4735 | if (test_tsk_need_resched(curr)) | |
4736 | return; | |
4737 | ||
a2f5c9ab DH |
4738 | /* Idle tasks are by definition preempted by non-idle tasks. */ |
4739 | if (unlikely(curr->policy == SCHED_IDLE) && | |
4740 | likely(p->policy != SCHED_IDLE)) | |
4741 | goto preempt; | |
4742 | ||
91c234b4 | 4743 | /* |
a2f5c9ab DH |
4744 | * Batch and idle tasks do not preempt non-idle tasks (their preemption |
4745 | * is driven by the tick): | |
91c234b4 | 4746 | */ |
8ed92e51 | 4747 | if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION)) |
91c234b4 | 4748 | return; |
bf0f6f24 | 4749 | |
464b7527 | 4750 | find_matching_se(&se, &pse); |
9bbd7374 | 4751 | update_curr(cfs_rq_of(se)); |
002f128b | 4752 | BUG_ON(!pse); |
2f36825b VP |
4753 | if (wakeup_preempt_entity(se, pse) == 1) { |
4754 | /* | |
4755 | * Bias pick_next to pick the sched entity that is | |
4756 | * triggering this preemption. | |
4757 | */ | |
4758 | if (!next_buddy_marked) | |
4759 | set_next_buddy(pse); | |
3a7e73a2 | 4760 | goto preempt; |
2f36825b | 4761 | } |
464b7527 | 4762 | |
3a7e73a2 | 4763 | return; |
a65ac745 | 4764 | |
3a7e73a2 | 4765 | preempt: |
8875125e | 4766 | resched_curr(rq); |
3a7e73a2 PZ |
4767 | /* |
4768 | * Only set the backward buddy when the current task is still | |
4769 | * on the rq. This can happen when a wakeup gets interleaved | |
4770 | * with schedule on the ->pre_schedule() or idle_balance() | |
4771 | * point, either of which can * drop the rq lock. | |
4772 | * | |
4773 | * Also, during early boot the idle thread is in the fair class, | |
4774 | * for obvious reasons its a bad idea to schedule back to it. | |
4775 | */ | |
4776 | if (unlikely(!se->on_rq || curr == rq->idle)) | |
4777 | return; | |
4778 | ||
4779 | if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se)) | |
4780 | set_last_buddy(se); | |
bf0f6f24 IM |
4781 | } |
4782 | ||
606dba2e PZ |
4783 | static struct task_struct * |
4784 | pick_next_task_fair(struct rq *rq, struct task_struct *prev) | |
bf0f6f24 IM |
4785 | { |
4786 | struct cfs_rq *cfs_rq = &rq->cfs; | |
4787 | struct sched_entity *se; | |
678d5718 | 4788 | struct task_struct *p; |
37e117c0 | 4789 | int new_tasks; |
678d5718 | 4790 | |
6e83125c | 4791 | again: |
678d5718 PZ |
4792 | #ifdef CONFIG_FAIR_GROUP_SCHED |
4793 | if (!cfs_rq->nr_running) | |
38033c37 | 4794 | goto idle; |
678d5718 | 4795 | |
3f1d2a31 | 4796 | if (prev->sched_class != &fair_sched_class) |
678d5718 PZ |
4797 | goto simple; |
4798 | ||
4799 | /* | |
4800 | * Because of the set_next_buddy() in dequeue_task_fair() it is rather | |
4801 | * likely that a next task is from the same cgroup as the current. | |
4802 | * | |
4803 | * Therefore attempt to avoid putting and setting the entire cgroup | |
4804 | * hierarchy, only change the part that actually changes. | |
4805 | */ | |
4806 | ||
4807 | do { | |
4808 | struct sched_entity *curr = cfs_rq->curr; | |
4809 | ||
4810 | /* | |
4811 | * Since we got here without doing put_prev_entity() we also | |
4812 | * have to consider cfs_rq->curr. If it is still a runnable | |
4813 | * entity, update_curr() will update its vruntime, otherwise | |
4814 | * forget we've ever seen it. | |
4815 | */ | |
4816 | if (curr && curr->on_rq) | |
4817 | update_curr(cfs_rq); | |
4818 | else | |
4819 | curr = NULL; | |
4820 | ||
4821 | /* | |
4822 | * This call to check_cfs_rq_runtime() will do the throttle and | |
4823 | * dequeue its entity in the parent(s). Therefore the 'simple' | |
4824 | * nr_running test will indeed be correct. | |
4825 | */ | |
4826 | if (unlikely(check_cfs_rq_runtime(cfs_rq))) | |
4827 | goto simple; | |
4828 | ||
4829 | se = pick_next_entity(cfs_rq, curr); | |
4830 | cfs_rq = group_cfs_rq(se); | |
4831 | } while (cfs_rq); | |
4832 | ||
4833 | p = task_of(se); | |
4834 | ||
4835 | /* | |
4836 | * Since we haven't yet done put_prev_entity and if the selected task | |
4837 | * is a different task than we started out with, try and touch the | |
4838 | * least amount of cfs_rqs. | |
4839 | */ | |
4840 | if (prev != p) { | |
4841 | struct sched_entity *pse = &prev->se; | |
4842 | ||
4843 | while (!(cfs_rq = is_same_group(se, pse))) { | |
4844 | int se_depth = se->depth; | |
4845 | int pse_depth = pse->depth; | |
4846 | ||
4847 | if (se_depth <= pse_depth) { | |
4848 | put_prev_entity(cfs_rq_of(pse), pse); | |
4849 | pse = parent_entity(pse); | |
4850 | } | |
4851 | if (se_depth >= pse_depth) { | |
4852 | set_next_entity(cfs_rq_of(se), se); | |
4853 | se = parent_entity(se); | |
4854 | } | |
4855 | } | |
4856 | ||
4857 | put_prev_entity(cfs_rq, pse); | |
4858 | set_next_entity(cfs_rq, se); | |
4859 | } | |
4860 | ||
4861 | if (hrtick_enabled(rq)) | |
4862 | hrtick_start_fair(rq, p); | |
4863 | ||
4864 | return p; | |
4865 | simple: | |
4866 | cfs_rq = &rq->cfs; | |
4867 | #endif | |
bf0f6f24 | 4868 | |
36ace27e | 4869 | if (!cfs_rq->nr_running) |
38033c37 | 4870 | goto idle; |
bf0f6f24 | 4871 | |
3f1d2a31 | 4872 | put_prev_task(rq, prev); |
606dba2e | 4873 | |
bf0f6f24 | 4874 | do { |
678d5718 | 4875 | se = pick_next_entity(cfs_rq, NULL); |
f4b6755f | 4876 | set_next_entity(cfs_rq, se); |
bf0f6f24 IM |
4877 | cfs_rq = group_cfs_rq(se); |
4878 | } while (cfs_rq); | |
4879 | ||
8f4d37ec | 4880 | p = task_of(se); |
678d5718 | 4881 | |
b39e66ea MG |
4882 | if (hrtick_enabled(rq)) |
4883 | hrtick_start_fair(rq, p); | |
8f4d37ec PZ |
4884 | |
4885 | return p; | |
38033c37 PZ |
4886 | |
4887 | idle: | |
e4aa358b | 4888 | new_tasks = idle_balance(rq); |
37e117c0 PZ |
4889 | /* |
4890 | * Because idle_balance() releases (and re-acquires) rq->lock, it is | |
4891 | * possible for any higher priority task to appear. In that case we | |
4892 | * must re-start the pick_next_entity() loop. | |
4893 | */ | |
e4aa358b | 4894 | if (new_tasks < 0) |
37e117c0 PZ |
4895 | return RETRY_TASK; |
4896 | ||
e4aa358b | 4897 | if (new_tasks > 0) |
38033c37 | 4898 | goto again; |
38033c37 PZ |
4899 | |
4900 | return NULL; | |
bf0f6f24 IM |
4901 | } |
4902 | ||
4903 | /* | |
4904 | * Account for a descheduled task: | |
4905 | */ | |
31ee529c | 4906 | static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) |
bf0f6f24 IM |
4907 | { |
4908 | struct sched_entity *se = &prev->se; | |
4909 | struct cfs_rq *cfs_rq; | |
4910 | ||
4911 | for_each_sched_entity(se) { | |
4912 | cfs_rq = cfs_rq_of(se); | |
ab6cde26 | 4913 | put_prev_entity(cfs_rq, se); |
bf0f6f24 IM |
4914 | } |
4915 | } | |
4916 | ||
ac53db59 RR |
4917 | /* |
4918 | * sched_yield() is very simple | |
4919 | * | |
4920 | * The magic of dealing with the ->skip buddy is in pick_next_entity. | |
4921 | */ | |
4922 | static void yield_task_fair(struct rq *rq) | |
4923 | { | |
4924 | struct task_struct *curr = rq->curr; | |
4925 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); | |
4926 | struct sched_entity *se = &curr->se; | |
4927 | ||
4928 | /* | |
4929 | * Are we the only task in the tree? | |
4930 | */ | |
4931 | if (unlikely(rq->nr_running == 1)) | |
4932 | return; | |
4933 | ||
4934 | clear_buddies(cfs_rq, se); | |
4935 | ||
4936 | if (curr->policy != SCHED_BATCH) { | |
4937 | update_rq_clock(rq); | |
4938 | /* | |
4939 | * Update run-time statistics of the 'current'. | |
4940 | */ | |
4941 | update_curr(cfs_rq); | |
916671c0 MG |
4942 | /* |
4943 | * Tell update_rq_clock() that we've just updated, | |
4944 | * so we don't do microscopic update in schedule() | |
4945 | * and double the fastpath cost. | |
4946 | */ | |
4947 | rq->skip_clock_update = 1; | |
ac53db59 RR |
4948 | } |
4949 | ||
4950 | set_skip_buddy(se); | |
4951 | } | |
4952 | ||
d95f4122 MG |
4953 | static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) |
4954 | { | |
4955 | struct sched_entity *se = &p->se; | |
4956 | ||
5238cdd3 PT |
4957 | /* throttled hierarchies are not runnable */ |
4958 | if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se))) | |
d95f4122 MG |
4959 | return false; |
4960 | ||
4961 | /* Tell the scheduler that we'd really like pse to run next. */ | |
4962 | set_next_buddy(se); | |
4963 | ||
d95f4122 MG |
4964 | yield_task_fair(rq); |
4965 | ||
4966 | return true; | |
4967 | } | |
4968 | ||
681f3e68 | 4969 | #ifdef CONFIG_SMP |
bf0f6f24 | 4970 | /************************************************** |
e9c84cb8 PZ |
4971 | * Fair scheduling class load-balancing methods. |
4972 | * | |
4973 | * BASICS | |
4974 | * | |
4975 | * The purpose of load-balancing is to achieve the same basic fairness the | |
4976 | * per-cpu scheduler provides, namely provide a proportional amount of compute | |
4977 | * time to each task. This is expressed in the following equation: | |
4978 | * | |
4979 | * W_i,n/P_i == W_j,n/P_j for all i,j (1) | |
4980 | * | |
4981 | * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight | |
4982 | * W_i,0 is defined as: | |
4983 | * | |
4984 | * W_i,0 = \Sum_j w_i,j (2) | |
4985 | * | |
4986 | * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight | |
4987 | * is derived from the nice value as per prio_to_weight[]. | |
4988 | * | |
4989 | * The weight average is an exponential decay average of the instantaneous | |
4990 | * weight: | |
4991 | * | |
4992 | * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3) | |
4993 | * | |
ced549fa | 4994 | * C_i is the compute capacity of cpu i, typically it is the |
e9c84cb8 PZ |
4995 | * fraction of 'recent' time available for SCHED_OTHER task execution. But it |
4996 | * can also include other factors [XXX]. | |
4997 | * | |
4998 | * To achieve this balance we define a measure of imbalance which follows | |
4999 | * directly from (1): | |
5000 | * | |
ced549fa | 5001 | * imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j } (4) |
e9c84cb8 PZ |
5002 | * |
5003 | * We them move tasks around to minimize the imbalance. In the continuous | |
5004 | * function space it is obvious this converges, in the discrete case we get | |
5005 | * a few fun cases generally called infeasible weight scenarios. | |
5006 | * | |
5007 | * [XXX expand on: | |
5008 | * - infeasible weights; | |
5009 | * - local vs global optima in the discrete case. ] | |
5010 | * | |
5011 | * | |
5012 | * SCHED DOMAINS | |
5013 | * | |
5014 | * In order to solve the imbalance equation (4), and avoid the obvious O(n^2) | |
5015 | * for all i,j solution, we create a tree of cpus that follows the hardware | |
5016 | * topology where each level pairs two lower groups (or better). This results | |
5017 | * in O(log n) layers. Furthermore we reduce the number of cpus going up the | |
5018 | * tree to only the first of the previous level and we decrease the frequency | |
5019 | * of load-balance at each level inv. proportional to the number of cpus in | |
5020 | * the groups. | |
5021 | * | |
5022 | * This yields: | |
5023 | * | |
5024 | * log_2 n 1 n | |
5025 | * \Sum { --- * --- * 2^i } = O(n) (5) | |
5026 | * i = 0 2^i 2^i | |
5027 | * `- size of each group | |
5028 | * | | `- number of cpus doing load-balance | |
5029 | * | `- freq | |
5030 | * `- sum over all levels | |
5031 | * | |
5032 | * Coupled with a limit on how many tasks we can migrate every balance pass, | |
5033 | * this makes (5) the runtime complexity of the balancer. | |
5034 | * | |
5035 | * An important property here is that each CPU is still (indirectly) connected | |
5036 | * to every other cpu in at most O(log n) steps: | |
5037 | * | |
5038 | * The adjacency matrix of the resulting graph is given by: | |
5039 | * | |
5040 | * log_2 n | |
5041 | * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6) | |
5042 | * k = 0 | |
5043 | * | |
5044 | * And you'll find that: | |
5045 | * | |
5046 | * A^(log_2 n)_i,j != 0 for all i,j (7) | |
5047 | * | |
5048 | * Showing there's indeed a path between every cpu in at most O(log n) steps. | |
5049 | * The task movement gives a factor of O(m), giving a convergence complexity | |
5050 | * of: | |
5051 | * | |
5052 | * O(nm log n), n := nr_cpus, m := nr_tasks (8) | |
5053 | * | |
5054 | * | |
5055 | * WORK CONSERVING | |
5056 | * | |
5057 | * In order to avoid CPUs going idle while there's still work to do, new idle | |
5058 | * balancing is more aggressive and has the newly idle cpu iterate up the domain | |
5059 | * tree itself instead of relying on other CPUs to bring it work. | |
5060 | * | |
5061 | * This adds some complexity to both (5) and (8) but it reduces the total idle | |
5062 | * time. | |
5063 | * | |
5064 | * [XXX more?] | |
5065 | * | |
5066 | * | |
5067 | * CGROUPS | |
5068 | * | |
5069 | * Cgroups make a horror show out of (2), instead of a simple sum we get: | |
5070 | * | |
5071 | * s_k,i | |
5072 | * W_i,0 = \Sum_j \Prod_k w_k * ----- (9) | |
5073 | * S_k | |
5074 | * | |
5075 | * Where | |
5076 | * | |
5077 | * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10) | |
5078 | * | |
5079 | * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i. | |
5080 | * | |
5081 | * The big problem is S_k, its a global sum needed to compute a local (W_i) | |
5082 | * property. | |
5083 | * | |
5084 | * [XXX write more on how we solve this.. _after_ merging pjt's patches that | |
5085 | * rewrite all of this once again.] | |
5086 | */ | |
bf0f6f24 | 5087 | |
ed387b78 HS |
5088 | static unsigned long __read_mostly max_load_balance_interval = HZ/10; |
5089 | ||
0ec8aa00 PZ |
5090 | enum fbq_type { regular, remote, all }; |
5091 | ||
ddcdf6e7 | 5092 | #define LBF_ALL_PINNED 0x01 |
367456c7 | 5093 | #define LBF_NEED_BREAK 0x02 |
6263322c PZ |
5094 | #define LBF_DST_PINNED 0x04 |
5095 | #define LBF_SOME_PINNED 0x08 | |
ddcdf6e7 PZ |
5096 | |
5097 | struct lb_env { | |
5098 | struct sched_domain *sd; | |
5099 | ||
ddcdf6e7 | 5100 | struct rq *src_rq; |
85c1e7da | 5101 | int src_cpu; |
ddcdf6e7 PZ |
5102 | |
5103 | int dst_cpu; | |
5104 | struct rq *dst_rq; | |
5105 | ||
88b8dac0 SV |
5106 | struct cpumask *dst_grpmask; |
5107 | int new_dst_cpu; | |
ddcdf6e7 | 5108 | enum cpu_idle_type idle; |
bd939f45 | 5109 | long imbalance; |
b9403130 MW |
5110 | /* The set of CPUs under consideration for load-balancing */ |
5111 | struct cpumask *cpus; | |
5112 | ||
ddcdf6e7 | 5113 | unsigned int flags; |
367456c7 PZ |
5114 | |
5115 | unsigned int loop; | |
5116 | unsigned int loop_break; | |
5117 | unsigned int loop_max; | |
0ec8aa00 PZ |
5118 | |
5119 | enum fbq_type fbq_type; | |
163122b7 | 5120 | struct list_head tasks; |
ddcdf6e7 PZ |
5121 | }; |
5122 | ||
029632fb PZ |
5123 | /* |
5124 | * Is this task likely cache-hot: | |
5125 | */ | |
5d5e2b1b | 5126 | static int task_hot(struct task_struct *p, struct lb_env *env) |
029632fb PZ |
5127 | { |
5128 | s64 delta; | |
5129 | ||
e5673f28 KT |
5130 | lockdep_assert_held(&env->src_rq->lock); |
5131 | ||
029632fb PZ |
5132 | if (p->sched_class != &fair_sched_class) |
5133 | return 0; | |
5134 | ||
5135 | if (unlikely(p->policy == SCHED_IDLE)) | |
5136 | return 0; | |
5137 | ||
5138 | /* | |
5139 | * Buddy candidates are cache hot: | |
5140 | */ | |
5d5e2b1b | 5141 | if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running && |
029632fb PZ |
5142 | (&p->se == cfs_rq_of(&p->se)->next || |
5143 | &p->se == cfs_rq_of(&p->se)->last)) | |
5144 | return 1; | |
5145 | ||
5146 | if (sysctl_sched_migration_cost == -1) | |
5147 | return 1; | |
5148 | if (sysctl_sched_migration_cost == 0) | |
5149 | return 0; | |
5150 | ||
5d5e2b1b | 5151 | delta = rq_clock_task(env->src_rq) - p->se.exec_start; |
029632fb PZ |
5152 | |
5153 | return delta < (s64)sysctl_sched_migration_cost; | |
5154 | } | |
5155 | ||
3a7053b3 MG |
5156 | #ifdef CONFIG_NUMA_BALANCING |
5157 | /* Returns true if the destination node has incurred more faults */ | |
5158 | static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env) | |
5159 | { | |
b1ad065e | 5160 | struct numa_group *numa_group = rcu_dereference(p->numa_group); |
3a7053b3 MG |
5161 | int src_nid, dst_nid; |
5162 | ||
ff1df896 | 5163 | if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults_memory || |
3a7053b3 MG |
5164 | !(env->sd->flags & SD_NUMA)) { |
5165 | return false; | |
5166 | } | |
5167 | ||
5168 | src_nid = cpu_to_node(env->src_cpu); | |
5169 | dst_nid = cpu_to_node(env->dst_cpu); | |
5170 | ||
83e1d2cd | 5171 | if (src_nid == dst_nid) |
3a7053b3 MG |
5172 | return false; |
5173 | ||
b1ad065e RR |
5174 | if (numa_group) { |
5175 | /* Task is already in the group's interleave set. */ | |
5176 | if (node_isset(src_nid, numa_group->active_nodes)) | |
5177 | return false; | |
83e1d2cd | 5178 | |
b1ad065e RR |
5179 | /* Task is moving into the group's interleave set. */ |
5180 | if (node_isset(dst_nid, numa_group->active_nodes)) | |
5181 | return true; | |
83e1d2cd | 5182 | |
b1ad065e RR |
5183 | return group_faults(p, dst_nid) > group_faults(p, src_nid); |
5184 | } | |
5185 | ||
5186 | /* Encourage migration to the preferred node. */ | |
5187 | if (dst_nid == p->numa_preferred_nid) | |
3a7053b3 MG |
5188 | return true; |
5189 | ||
b1ad065e | 5190 | return task_faults(p, dst_nid) > task_faults(p, src_nid); |
3a7053b3 | 5191 | } |
7a0f3083 MG |
5192 | |
5193 | ||
5194 | static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env) | |
5195 | { | |
b1ad065e | 5196 | struct numa_group *numa_group = rcu_dereference(p->numa_group); |
7a0f3083 MG |
5197 | int src_nid, dst_nid; |
5198 | ||
5199 | if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER)) | |
5200 | return false; | |
5201 | ||
ff1df896 | 5202 | if (!p->numa_faults_memory || !(env->sd->flags & SD_NUMA)) |
7a0f3083 MG |
5203 | return false; |
5204 | ||
5205 | src_nid = cpu_to_node(env->src_cpu); | |
5206 | dst_nid = cpu_to_node(env->dst_cpu); | |
5207 | ||
83e1d2cd | 5208 | if (src_nid == dst_nid) |
7a0f3083 MG |
5209 | return false; |
5210 | ||
b1ad065e RR |
5211 | if (numa_group) { |
5212 | /* Task is moving within/into the group's interleave set. */ | |
5213 | if (node_isset(dst_nid, numa_group->active_nodes)) | |
5214 | return false; | |
5215 | ||
5216 | /* Task is moving out of the group's interleave set. */ | |
5217 | if (node_isset(src_nid, numa_group->active_nodes)) | |
5218 | return true; | |
5219 | ||
5220 | return group_faults(p, dst_nid) < group_faults(p, src_nid); | |
5221 | } | |
5222 | ||
83e1d2cd MG |
5223 | /* Migrating away from the preferred node is always bad. */ |
5224 | if (src_nid == p->numa_preferred_nid) | |
5225 | return true; | |
5226 | ||
b1ad065e | 5227 | return task_faults(p, dst_nid) < task_faults(p, src_nid); |
7a0f3083 MG |
5228 | } |
5229 | ||
3a7053b3 MG |
5230 | #else |
5231 | static inline bool migrate_improves_locality(struct task_struct *p, | |
5232 | struct lb_env *env) | |
5233 | { | |
5234 | return false; | |
5235 | } | |
7a0f3083 MG |
5236 | |
5237 | static inline bool migrate_degrades_locality(struct task_struct *p, | |
5238 | struct lb_env *env) | |
5239 | { | |
5240 | return false; | |
5241 | } | |
3a7053b3 MG |
5242 | #endif |
5243 | ||
1e3c88bd PZ |
5244 | /* |
5245 | * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? | |
5246 | */ | |
5247 | static | |
8e45cb54 | 5248 | int can_migrate_task(struct task_struct *p, struct lb_env *env) |
1e3c88bd PZ |
5249 | { |
5250 | int tsk_cache_hot = 0; | |
e5673f28 KT |
5251 | |
5252 | lockdep_assert_held(&env->src_rq->lock); | |
5253 | ||
1e3c88bd PZ |
5254 | /* |
5255 | * We do not migrate tasks that are: | |
d3198084 | 5256 | * 1) throttled_lb_pair, or |
1e3c88bd | 5257 | * 2) cannot be migrated to this CPU due to cpus_allowed, or |
d3198084 JK |
5258 | * 3) running (obviously), or |
5259 | * 4) are cache-hot on their current CPU. | |
1e3c88bd | 5260 | */ |
d3198084 JK |
5261 | if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) |
5262 | return 0; | |
5263 | ||
ddcdf6e7 | 5264 | if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) { |
e02e60c1 | 5265 | int cpu; |
88b8dac0 | 5266 | |
41acab88 | 5267 | schedstat_inc(p, se.statistics.nr_failed_migrations_affine); |
88b8dac0 | 5268 | |
6263322c PZ |
5269 | env->flags |= LBF_SOME_PINNED; |
5270 | ||
88b8dac0 SV |
5271 | /* |
5272 | * Remember if this task can be migrated to any other cpu in | |
5273 | * our sched_group. We may want to revisit it if we couldn't | |
5274 | * meet load balance goals by pulling other tasks on src_cpu. | |
5275 | * | |
5276 | * Also avoid computing new_dst_cpu if we have already computed | |
5277 | * one in current iteration. | |
5278 | */ | |
6263322c | 5279 | if (!env->dst_grpmask || (env->flags & LBF_DST_PINNED)) |
88b8dac0 SV |
5280 | return 0; |
5281 | ||
e02e60c1 JK |
5282 | /* Prevent to re-select dst_cpu via env's cpus */ |
5283 | for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) { | |
5284 | if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) { | |
6263322c | 5285 | env->flags |= LBF_DST_PINNED; |
e02e60c1 JK |
5286 | env->new_dst_cpu = cpu; |
5287 | break; | |
5288 | } | |
88b8dac0 | 5289 | } |
e02e60c1 | 5290 | |
1e3c88bd PZ |
5291 | return 0; |
5292 | } | |
88b8dac0 SV |
5293 | |
5294 | /* Record that we found atleast one task that could run on dst_cpu */ | |
8e45cb54 | 5295 | env->flags &= ~LBF_ALL_PINNED; |
1e3c88bd | 5296 | |
ddcdf6e7 | 5297 | if (task_running(env->src_rq, p)) { |
41acab88 | 5298 | schedstat_inc(p, se.statistics.nr_failed_migrations_running); |
1e3c88bd PZ |
5299 | return 0; |
5300 | } | |
5301 | ||
5302 | /* | |
5303 | * Aggressive migration if: | |
3a7053b3 MG |
5304 | * 1) destination numa is preferred |
5305 | * 2) task is cache cold, or | |
5306 | * 3) too many balance attempts have failed. | |
1e3c88bd | 5307 | */ |
5d5e2b1b | 5308 | tsk_cache_hot = task_hot(p, env); |
7a0f3083 MG |
5309 | if (!tsk_cache_hot) |
5310 | tsk_cache_hot = migrate_degrades_locality(p, env); | |
3a7053b3 MG |
5311 | |
5312 | if (migrate_improves_locality(p, env)) { | |
5313 | #ifdef CONFIG_SCHEDSTATS | |
5314 | if (tsk_cache_hot) { | |
5315 | schedstat_inc(env->sd, lb_hot_gained[env->idle]); | |
5316 | schedstat_inc(p, se.statistics.nr_forced_migrations); | |
5317 | } | |
5318 | #endif | |
5319 | return 1; | |
5320 | } | |
5321 | ||
1e3c88bd | 5322 | if (!tsk_cache_hot || |
8e45cb54 | 5323 | env->sd->nr_balance_failed > env->sd->cache_nice_tries) { |
4e2dcb73 | 5324 | |
1e3c88bd | 5325 | if (tsk_cache_hot) { |
8e45cb54 | 5326 | schedstat_inc(env->sd, lb_hot_gained[env->idle]); |
41acab88 | 5327 | schedstat_inc(p, se.statistics.nr_forced_migrations); |
1e3c88bd | 5328 | } |
4e2dcb73 | 5329 | |
1e3c88bd PZ |
5330 | return 1; |
5331 | } | |
5332 | ||
4e2dcb73 ZH |
5333 | schedstat_inc(p, se.statistics.nr_failed_migrations_hot); |
5334 | return 0; | |
1e3c88bd PZ |
5335 | } |
5336 | ||
163122b7 KT |
5337 | /* |
5338 | * detach_task() -- detach the task for the migration specified in env | |
5339 | */ | |
5340 | static void detach_task(struct task_struct *p, struct lb_env *env) | |
5341 | { | |
5342 | lockdep_assert_held(&env->src_rq->lock); | |
5343 | ||
5344 | deactivate_task(env->src_rq, p, 0); | |
5345 | p->on_rq = TASK_ON_RQ_MIGRATING; | |
5346 | set_task_cpu(p, env->dst_cpu); | |
5347 | } | |
5348 | ||
897c395f | 5349 | /* |
e5673f28 | 5350 | * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as |
897c395f | 5351 | * part of active balancing operations within "domain". |
897c395f | 5352 | * |
e5673f28 | 5353 | * Returns a task if successful and NULL otherwise. |
897c395f | 5354 | */ |
e5673f28 | 5355 | static struct task_struct *detach_one_task(struct lb_env *env) |
897c395f PZ |
5356 | { |
5357 | struct task_struct *p, *n; | |
897c395f | 5358 | |
e5673f28 KT |
5359 | lockdep_assert_held(&env->src_rq->lock); |
5360 | ||
367456c7 | 5361 | list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) { |
367456c7 PZ |
5362 | if (!can_migrate_task(p, env)) |
5363 | continue; | |
897c395f | 5364 | |
163122b7 | 5365 | detach_task(p, env); |
e5673f28 | 5366 | |
367456c7 | 5367 | /* |
e5673f28 | 5368 | * Right now, this is only the second place where |
163122b7 | 5369 | * lb_gained[env->idle] is updated (other is detach_tasks) |
e5673f28 | 5370 | * so we can safely collect stats here rather than |
163122b7 | 5371 | * inside detach_tasks(). |
367456c7 PZ |
5372 | */ |
5373 | schedstat_inc(env->sd, lb_gained[env->idle]); | |
e5673f28 | 5374 | return p; |
897c395f | 5375 | } |
e5673f28 KT |
5376 | return NULL; |
5377 | } | |
5378 | ||
eb95308e PZ |
5379 | static const unsigned int sched_nr_migrate_break = 32; |
5380 | ||
5d6523eb | 5381 | /* |
163122b7 KT |
5382 | * detach_tasks() -- tries to detach up to imbalance weighted load from |
5383 | * busiest_rq, as part of a balancing operation within domain "sd". | |
5d6523eb | 5384 | * |
163122b7 | 5385 | * Returns number of detached tasks if successful and 0 otherwise. |
5d6523eb | 5386 | */ |
163122b7 | 5387 | static int detach_tasks(struct lb_env *env) |
1e3c88bd | 5388 | { |
5d6523eb PZ |
5389 | struct list_head *tasks = &env->src_rq->cfs_tasks; |
5390 | struct task_struct *p; | |
367456c7 | 5391 | unsigned long load; |
163122b7 KT |
5392 | int detached = 0; |
5393 | ||
5394 | lockdep_assert_held(&env->src_rq->lock); | |
1e3c88bd | 5395 | |
bd939f45 | 5396 | if (env->imbalance <= 0) |
5d6523eb | 5397 | return 0; |
1e3c88bd | 5398 | |
5d6523eb PZ |
5399 | while (!list_empty(tasks)) { |
5400 | p = list_first_entry(tasks, struct task_struct, se.group_node); | |
1e3c88bd | 5401 | |
367456c7 PZ |
5402 | env->loop++; |
5403 | /* We've more or less seen every task there is, call it quits */ | |
5d6523eb | 5404 | if (env->loop > env->loop_max) |
367456c7 | 5405 | break; |
5d6523eb PZ |
5406 | |
5407 | /* take a breather every nr_migrate tasks */ | |
367456c7 | 5408 | if (env->loop > env->loop_break) { |
eb95308e | 5409 | env->loop_break += sched_nr_migrate_break; |
8e45cb54 | 5410 | env->flags |= LBF_NEED_BREAK; |
ee00e66f | 5411 | break; |
a195f004 | 5412 | } |
1e3c88bd | 5413 | |
d3198084 | 5414 | if (!can_migrate_task(p, env)) |
367456c7 PZ |
5415 | goto next; |
5416 | ||
5417 | load = task_h_load(p); | |
5d6523eb | 5418 | |
eb95308e | 5419 | if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed) |
367456c7 PZ |
5420 | goto next; |
5421 | ||
bd939f45 | 5422 | if ((load / 2) > env->imbalance) |
367456c7 | 5423 | goto next; |
1e3c88bd | 5424 | |
163122b7 KT |
5425 | detach_task(p, env); |
5426 | list_add(&p->se.group_node, &env->tasks); | |
5427 | ||
5428 | detached++; | |
bd939f45 | 5429 | env->imbalance -= load; |
1e3c88bd PZ |
5430 | |
5431 | #ifdef CONFIG_PREEMPT | |
ee00e66f PZ |
5432 | /* |
5433 | * NEWIDLE balancing is a source of latency, so preemptible | |
163122b7 | 5434 | * kernels will stop after the first task is detached to minimize |
ee00e66f PZ |
5435 | * the critical section. |
5436 | */ | |
5d6523eb | 5437 | if (env->idle == CPU_NEWLY_IDLE) |
ee00e66f | 5438 | break; |
1e3c88bd PZ |
5439 | #endif |
5440 | ||
ee00e66f PZ |
5441 | /* |
5442 | * We only want to steal up to the prescribed amount of | |
5443 | * weighted load. | |
5444 | */ | |
bd939f45 | 5445 | if (env->imbalance <= 0) |
ee00e66f | 5446 | break; |
367456c7 PZ |
5447 | |
5448 | continue; | |
5449 | next: | |
5d6523eb | 5450 | list_move_tail(&p->se.group_node, tasks); |
1e3c88bd | 5451 | } |
5d6523eb | 5452 | |
1e3c88bd | 5453 | /* |
163122b7 KT |
5454 | * Right now, this is one of only two places we collect this stat |
5455 | * so we can safely collect detach_one_task() stats here rather | |
5456 | * than inside detach_one_task(). | |
1e3c88bd | 5457 | */ |
163122b7 | 5458 | schedstat_add(env->sd, lb_gained[env->idle], detached); |
1e3c88bd | 5459 | |
163122b7 KT |
5460 | return detached; |
5461 | } | |
5462 | ||
5463 | /* | |
5464 | * attach_task() -- attach the task detached by detach_task() to its new rq. | |
5465 | */ | |
5466 | static void attach_task(struct rq *rq, struct task_struct *p) | |
5467 | { | |
5468 | lockdep_assert_held(&rq->lock); | |
5469 | ||
5470 | BUG_ON(task_rq(p) != rq); | |
5471 | p->on_rq = TASK_ON_RQ_QUEUED; | |
5472 | activate_task(rq, p, 0); | |
5473 | check_preempt_curr(rq, p, 0); | |
5474 | } | |
5475 | ||
5476 | /* | |
5477 | * attach_one_task() -- attaches the task returned from detach_one_task() to | |
5478 | * its new rq. | |
5479 | */ | |
5480 | static void attach_one_task(struct rq *rq, struct task_struct *p) | |
5481 | { | |
5482 | raw_spin_lock(&rq->lock); | |
5483 | attach_task(rq, p); | |
5484 | raw_spin_unlock(&rq->lock); | |
5485 | } | |
5486 | ||
5487 | /* | |
5488 | * attach_tasks() -- attaches all tasks detached by detach_tasks() to their | |
5489 | * new rq. | |
5490 | */ | |
5491 | static void attach_tasks(struct lb_env *env) | |
5492 | { | |
5493 | struct list_head *tasks = &env->tasks; | |
5494 | struct task_struct *p; | |
5495 | ||
5496 | raw_spin_lock(&env->dst_rq->lock); | |
5497 | ||
5498 | while (!list_empty(tasks)) { | |
5499 | p = list_first_entry(tasks, struct task_struct, se.group_node); | |
5500 | list_del_init(&p->se.group_node); | |
5501 | ||
5502 | attach_task(env->dst_rq, p); | |
5503 | } | |
5504 | ||
5505 | raw_spin_unlock(&env->dst_rq->lock); | |
1e3c88bd PZ |
5506 | } |
5507 | ||
230059de | 5508 | #ifdef CONFIG_FAIR_GROUP_SCHED |
9e3081ca PZ |
5509 | /* |
5510 | * update tg->load_weight by folding this cpu's load_avg | |
5511 | */ | |
48a16753 | 5512 | static void __update_blocked_averages_cpu(struct task_group *tg, int cpu) |
9e3081ca | 5513 | { |
48a16753 PT |
5514 | struct sched_entity *se = tg->se[cpu]; |
5515 | struct cfs_rq *cfs_rq = tg->cfs_rq[cpu]; | |
9e3081ca | 5516 | |
48a16753 PT |
5517 | /* throttled entities do not contribute to load */ |
5518 | if (throttled_hierarchy(cfs_rq)) | |
5519 | return; | |
9e3081ca | 5520 | |
aff3e498 | 5521 | update_cfs_rq_blocked_load(cfs_rq, 1); |
9e3081ca | 5522 | |
82958366 PT |
5523 | if (se) { |
5524 | update_entity_load_avg(se, 1); | |
5525 | /* | |
5526 | * We pivot on our runnable average having decayed to zero for | |
5527 | * list removal. This generally implies that all our children | |
5528 | * have also been removed (modulo rounding error or bandwidth | |
5529 | * control); however, such cases are rare and we can fix these | |
5530 | * at enqueue. | |
5531 | * | |
5532 | * TODO: fix up out-of-order children on enqueue. | |
5533 | */ | |
5534 | if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running) | |
5535 | list_del_leaf_cfs_rq(cfs_rq); | |
5536 | } else { | |
48a16753 | 5537 | struct rq *rq = rq_of(cfs_rq); |
82958366 PT |
5538 | update_rq_runnable_avg(rq, rq->nr_running); |
5539 | } | |
9e3081ca PZ |
5540 | } |
5541 | ||
48a16753 | 5542 | static void update_blocked_averages(int cpu) |
9e3081ca | 5543 | { |
9e3081ca | 5544 | struct rq *rq = cpu_rq(cpu); |
48a16753 PT |
5545 | struct cfs_rq *cfs_rq; |
5546 | unsigned long flags; | |
9e3081ca | 5547 | |
48a16753 PT |
5548 | raw_spin_lock_irqsave(&rq->lock, flags); |
5549 | update_rq_clock(rq); | |
9763b67f PZ |
5550 | /* |
5551 | * Iterates the task_group tree in a bottom up fashion, see | |
5552 | * list_add_leaf_cfs_rq() for details. | |
5553 | */ | |
64660c86 | 5554 | for_each_leaf_cfs_rq(rq, cfs_rq) { |
48a16753 PT |
5555 | /* |
5556 | * Note: We may want to consider periodically releasing | |
5557 | * rq->lock about these updates so that creating many task | |
5558 | * groups does not result in continually extending hold time. | |
5559 | */ | |
5560 | __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu); | |
64660c86 | 5561 | } |
48a16753 PT |
5562 | |
5563 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
9e3081ca PZ |
5564 | } |
5565 | ||
9763b67f | 5566 | /* |
68520796 | 5567 | * Compute the hierarchical load factor for cfs_rq and all its ascendants. |
9763b67f PZ |
5568 | * This needs to be done in a top-down fashion because the load of a child |
5569 | * group is a fraction of its parents load. | |
5570 | */ | |
68520796 | 5571 | static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq) |
9763b67f | 5572 | { |
68520796 VD |
5573 | struct rq *rq = rq_of(cfs_rq); |
5574 | struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)]; | |
a35b6466 | 5575 | unsigned long now = jiffies; |
68520796 | 5576 | unsigned long load; |
a35b6466 | 5577 | |
68520796 | 5578 | if (cfs_rq->last_h_load_update == now) |
a35b6466 PZ |
5579 | return; |
5580 | ||
68520796 VD |
5581 | cfs_rq->h_load_next = NULL; |
5582 | for_each_sched_entity(se) { | |
5583 | cfs_rq = cfs_rq_of(se); | |
5584 | cfs_rq->h_load_next = se; | |
5585 | if (cfs_rq->last_h_load_update == now) | |
5586 | break; | |
5587 | } | |
a35b6466 | 5588 | |
68520796 | 5589 | if (!se) { |
7e3115ef | 5590 | cfs_rq->h_load = cfs_rq->runnable_load_avg; |
68520796 VD |
5591 | cfs_rq->last_h_load_update = now; |
5592 | } | |
5593 | ||
5594 | while ((se = cfs_rq->h_load_next) != NULL) { | |
5595 | load = cfs_rq->h_load; | |
5596 | load = div64_ul(load * se->avg.load_avg_contrib, | |
5597 | cfs_rq->runnable_load_avg + 1); | |
5598 | cfs_rq = group_cfs_rq(se); | |
5599 | cfs_rq->h_load = load; | |
5600 | cfs_rq->last_h_load_update = now; | |
5601 | } | |
9763b67f PZ |
5602 | } |
5603 | ||
367456c7 | 5604 | static unsigned long task_h_load(struct task_struct *p) |
230059de | 5605 | { |
367456c7 | 5606 | struct cfs_rq *cfs_rq = task_cfs_rq(p); |
230059de | 5607 | |
68520796 | 5608 | update_cfs_rq_h_load(cfs_rq); |
a003a25b AS |
5609 | return div64_ul(p->se.avg.load_avg_contrib * cfs_rq->h_load, |
5610 | cfs_rq->runnable_load_avg + 1); | |
230059de PZ |
5611 | } |
5612 | #else | |
48a16753 | 5613 | static inline void update_blocked_averages(int cpu) |
9e3081ca PZ |
5614 | { |
5615 | } | |
5616 | ||
367456c7 | 5617 | static unsigned long task_h_load(struct task_struct *p) |
1e3c88bd | 5618 | { |
a003a25b | 5619 | return p->se.avg.load_avg_contrib; |
1e3c88bd | 5620 | } |
230059de | 5621 | #endif |
1e3c88bd | 5622 | |
1e3c88bd | 5623 | /********** Helpers for find_busiest_group ************************/ |
caeb178c RR |
5624 | |
5625 | enum group_type { | |
5626 | group_other = 0, | |
5627 | group_imbalanced, | |
5628 | group_overloaded, | |
5629 | }; | |
5630 | ||
1e3c88bd PZ |
5631 | /* |
5632 | * sg_lb_stats - stats of a sched_group required for load_balancing | |
5633 | */ | |
5634 | struct sg_lb_stats { | |
5635 | unsigned long avg_load; /*Avg load across the CPUs of the group */ | |
5636 | unsigned long group_load; /* Total load over the CPUs of the group */ | |
1e3c88bd | 5637 | unsigned long sum_weighted_load; /* Weighted load of group's tasks */ |
56cf515b | 5638 | unsigned long load_per_task; |
63b2ca30 | 5639 | unsigned long group_capacity; |
147c5fc2 | 5640 | unsigned int sum_nr_running; /* Nr tasks running in the group */ |
0fedc6c8 | 5641 | unsigned int group_capacity_factor; |
147c5fc2 PZ |
5642 | unsigned int idle_cpus; |
5643 | unsigned int group_weight; | |
caeb178c | 5644 | enum group_type group_type; |
1b6a7495 | 5645 | int group_has_free_capacity; |
0ec8aa00 PZ |
5646 | #ifdef CONFIG_NUMA_BALANCING |
5647 | unsigned int nr_numa_running; | |
5648 | unsigned int nr_preferred_running; | |
5649 | #endif | |
1e3c88bd PZ |
5650 | }; |
5651 | ||
56cf515b JK |
5652 | /* |
5653 | * sd_lb_stats - Structure to store the statistics of a sched_domain | |
5654 | * during load balancing. | |
5655 | */ | |
5656 | struct sd_lb_stats { | |
5657 | struct sched_group *busiest; /* Busiest group in this sd */ | |
5658 | struct sched_group *local; /* Local group in this sd */ | |
5659 | unsigned long total_load; /* Total load of all groups in sd */ | |
63b2ca30 | 5660 | unsigned long total_capacity; /* Total capacity of all groups in sd */ |
56cf515b JK |
5661 | unsigned long avg_load; /* Average load across all groups in sd */ |
5662 | ||
56cf515b | 5663 | struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */ |
147c5fc2 | 5664 | struct sg_lb_stats local_stat; /* Statistics of the local group */ |
56cf515b JK |
5665 | }; |
5666 | ||
147c5fc2 PZ |
5667 | static inline void init_sd_lb_stats(struct sd_lb_stats *sds) |
5668 | { | |
5669 | /* | |
5670 | * Skimp on the clearing to avoid duplicate work. We can avoid clearing | |
5671 | * local_stat because update_sg_lb_stats() does a full clear/assignment. | |
5672 | * We must however clear busiest_stat::avg_load because | |
5673 | * update_sd_pick_busiest() reads this before assignment. | |
5674 | */ | |
5675 | *sds = (struct sd_lb_stats){ | |
5676 | .busiest = NULL, | |
5677 | .local = NULL, | |
5678 | .total_load = 0UL, | |
63b2ca30 | 5679 | .total_capacity = 0UL, |
147c5fc2 PZ |
5680 | .busiest_stat = { |
5681 | .avg_load = 0UL, | |
caeb178c RR |
5682 | .sum_nr_running = 0, |
5683 | .group_type = group_other, | |
147c5fc2 PZ |
5684 | }, |
5685 | }; | |
5686 | } | |
5687 | ||
1e3c88bd PZ |
5688 | /** |
5689 | * get_sd_load_idx - Obtain the load index for a given sched domain. | |
5690 | * @sd: The sched_domain whose load_idx is to be obtained. | |
ed1b7732 | 5691 | * @idle: The idle status of the CPU for whose sd load_idx is obtained. |
e69f6186 YB |
5692 | * |
5693 | * Return: The load index. | |
1e3c88bd PZ |
5694 | */ |
5695 | static inline int get_sd_load_idx(struct sched_domain *sd, | |
5696 | enum cpu_idle_type idle) | |
5697 | { | |
5698 | int load_idx; | |
5699 | ||
5700 | switch (idle) { | |
5701 | case CPU_NOT_IDLE: | |
5702 | load_idx = sd->busy_idx; | |
5703 | break; | |
5704 | ||
5705 | case CPU_NEWLY_IDLE: | |
5706 | load_idx = sd->newidle_idx; | |
5707 | break; | |
5708 | default: | |
5709 | load_idx = sd->idle_idx; | |
5710 | break; | |
5711 | } | |
5712 | ||
5713 | return load_idx; | |
5714 | } | |
5715 | ||
ced549fa | 5716 | static unsigned long default_scale_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 5717 | { |
ca8ce3d0 | 5718 | return SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
5719 | } |
5720 | ||
ca8ce3d0 | 5721 | unsigned long __weak arch_scale_freq_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 5722 | { |
ced549fa | 5723 | return default_scale_capacity(sd, cpu); |
1e3c88bd PZ |
5724 | } |
5725 | ||
ced549fa | 5726 | static unsigned long default_scale_smt_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 5727 | { |
669c55e9 | 5728 | unsigned long weight = sd->span_weight; |
1e3c88bd PZ |
5729 | unsigned long smt_gain = sd->smt_gain; |
5730 | ||
5731 | smt_gain /= weight; | |
5732 | ||
5733 | return smt_gain; | |
5734 | } | |
5735 | ||
ca8ce3d0 | 5736 | unsigned long __weak arch_scale_smt_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 5737 | { |
ced549fa | 5738 | return default_scale_smt_capacity(sd, cpu); |
1e3c88bd PZ |
5739 | } |
5740 | ||
ced549fa | 5741 | static unsigned long scale_rt_capacity(int cpu) |
1e3c88bd PZ |
5742 | { |
5743 | struct rq *rq = cpu_rq(cpu); | |
b654f7de | 5744 | u64 total, available, age_stamp, avg; |
cadefd3d | 5745 | s64 delta; |
1e3c88bd | 5746 | |
b654f7de PZ |
5747 | /* |
5748 | * Since we're reading these variables without serialization make sure | |
5749 | * we read them once before doing sanity checks on them. | |
5750 | */ | |
5751 | age_stamp = ACCESS_ONCE(rq->age_stamp); | |
5752 | avg = ACCESS_ONCE(rq->rt_avg); | |
5753 | ||
cadefd3d PZ |
5754 | delta = rq_clock(rq) - age_stamp; |
5755 | if (unlikely(delta < 0)) | |
5756 | delta = 0; | |
5757 | ||
5758 | total = sched_avg_period() + delta; | |
aa483808 | 5759 | |
b654f7de | 5760 | if (unlikely(total < avg)) { |
ced549fa | 5761 | /* Ensures that capacity won't end up being negative */ |
aa483808 VP |
5762 | available = 0; |
5763 | } else { | |
b654f7de | 5764 | available = total - avg; |
aa483808 | 5765 | } |
1e3c88bd | 5766 | |
ca8ce3d0 NP |
5767 | if (unlikely((s64)total < SCHED_CAPACITY_SCALE)) |
5768 | total = SCHED_CAPACITY_SCALE; | |
1e3c88bd | 5769 | |
ca8ce3d0 | 5770 | total >>= SCHED_CAPACITY_SHIFT; |
1e3c88bd PZ |
5771 | |
5772 | return div_u64(available, total); | |
5773 | } | |
5774 | ||
ced549fa | 5775 | static void update_cpu_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd | 5776 | { |
669c55e9 | 5777 | unsigned long weight = sd->span_weight; |
ca8ce3d0 | 5778 | unsigned long capacity = SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
5779 | struct sched_group *sdg = sd->groups; |
5780 | ||
5d4dfddd NP |
5781 | if ((sd->flags & SD_SHARE_CPUCAPACITY) && weight > 1) { |
5782 | if (sched_feat(ARCH_CAPACITY)) | |
ca8ce3d0 | 5783 | capacity *= arch_scale_smt_capacity(sd, cpu); |
1e3c88bd | 5784 | else |
ced549fa | 5785 | capacity *= default_scale_smt_capacity(sd, cpu); |
1e3c88bd | 5786 | |
ca8ce3d0 | 5787 | capacity >>= SCHED_CAPACITY_SHIFT; |
1e3c88bd PZ |
5788 | } |
5789 | ||
ced549fa | 5790 | sdg->sgc->capacity_orig = capacity; |
9d5efe05 | 5791 | |
5d4dfddd | 5792 | if (sched_feat(ARCH_CAPACITY)) |
ca8ce3d0 | 5793 | capacity *= arch_scale_freq_capacity(sd, cpu); |
9d5efe05 | 5794 | else |
ced549fa | 5795 | capacity *= default_scale_capacity(sd, cpu); |
9d5efe05 | 5796 | |
ca8ce3d0 | 5797 | capacity >>= SCHED_CAPACITY_SHIFT; |
9d5efe05 | 5798 | |
ced549fa | 5799 | capacity *= scale_rt_capacity(cpu); |
ca8ce3d0 | 5800 | capacity >>= SCHED_CAPACITY_SHIFT; |
1e3c88bd | 5801 | |
ced549fa NP |
5802 | if (!capacity) |
5803 | capacity = 1; | |
1e3c88bd | 5804 | |
ced549fa NP |
5805 | cpu_rq(cpu)->cpu_capacity = capacity; |
5806 | sdg->sgc->capacity = capacity; | |
1e3c88bd PZ |
5807 | } |
5808 | ||
63b2ca30 | 5809 | void update_group_capacity(struct sched_domain *sd, int cpu) |
1e3c88bd PZ |
5810 | { |
5811 | struct sched_domain *child = sd->child; | |
5812 | struct sched_group *group, *sdg = sd->groups; | |
63b2ca30 | 5813 | unsigned long capacity, capacity_orig; |
4ec4412e VG |
5814 | unsigned long interval; |
5815 | ||
5816 | interval = msecs_to_jiffies(sd->balance_interval); | |
5817 | interval = clamp(interval, 1UL, max_load_balance_interval); | |
63b2ca30 | 5818 | sdg->sgc->next_update = jiffies + interval; |
1e3c88bd PZ |
5819 | |
5820 | if (!child) { | |
ced549fa | 5821 | update_cpu_capacity(sd, cpu); |
1e3c88bd PZ |
5822 | return; |
5823 | } | |
5824 | ||
63b2ca30 | 5825 | capacity_orig = capacity = 0; |
1e3c88bd | 5826 | |
74a5ce20 PZ |
5827 | if (child->flags & SD_OVERLAP) { |
5828 | /* | |
5829 | * SD_OVERLAP domains cannot assume that child groups | |
5830 | * span the current group. | |
5831 | */ | |
5832 | ||
863bffc8 | 5833 | for_each_cpu(cpu, sched_group_cpus(sdg)) { |
63b2ca30 | 5834 | struct sched_group_capacity *sgc; |
9abf24d4 | 5835 | struct rq *rq = cpu_rq(cpu); |
863bffc8 | 5836 | |
9abf24d4 | 5837 | /* |
63b2ca30 | 5838 | * build_sched_domains() -> init_sched_groups_capacity() |
9abf24d4 SD |
5839 | * gets here before we've attached the domains to the |
5840 | * runqueues. | |
5841 | * | |
ced549fa NP |
5842 | * Use capacity_of(), which is set irrespective of domains |
5843 | * in update_cpu_capacity(). | |
9abf24d4 | 5844 | * |
63b2ca30 | 5845 | * This avoids capacity/capacity_orig from being 0 and |
9abf24d4 SD |
5846 | * causing divide-by-zero issues on boot. |
5847 | * | |
63b2ca30 | 5848 | * Runtime updates will correct capacity_orig. |
9abf24d4 SD |
5849 | */ |
5850 | if (unlikely(!rq->sd)) { | |
ced549fa NP |
5851 | capacity_orig += capacity_of(cpu); |
5852 | capacity += capacity_of(cpu); | |
9abf24d4 SD |
5853 | continue; |
5854 | } | |
863bffc8 | 5855 | |
63b2ca30 NP |
5856 | sgc = rq->sd->groups->sgc; |
5857 | capacity_orig += sgc->capacity_orig; | |
5858 | capacity += sgc->capacity; | |
863bffc8 | 5859 | } |
74a5ce20 PZ |
5860 | } else { |
5861 | /* | |
5862 | * !SD_OVERLAP domains can assume that child groups | |
5863 | * span the current group. | |
5864 | */ | |
5865 | ||
5866 | group = child->groups; | |
5867 | do { | |
63b2ca30 NP |
5868 | capacity_orig += group->sgc->capacity_orig; |
5869 | capacity += group->sgc->capacity; | |
74a5ce20 PZ |
5870 | group = group->next; |
5871 | } while (group != child->groups); | |
5872 | } | |
1e3c88bd | 5873 | |
63b2ca30 NP |
5874 | sdg->sgc->capacity_orig = capacity_orig; |
5875 | sdg->sgc->capacity = capacity; | |
1e3c88bd PZ |
5876 | } |
5877 | ||
9d5efe05 SV |
5878 | /* |
5879 | * Try and fix up capacity for tiny siblings, this is needed when | |
5880 | * things like SD_ASYM_PACKING need f_b_g to select another sibling | |
5881 | * which on its own isn't powerful enough. | |
5882 | * | |
5883 | * See update_sd_pick_busiest() and check_asym_packing(). | |
5884 | */ | |
5885 | static inline int | |
5886 | fix_small_capacity(struct sched_domain *sd, struct sched_group *group) | |
5887 | { | |
5888 | /* | |
ca8ce3d0 | 5889 | * Only siblings can have significantly less than SCHED_CAPACITY_SCALE |
9d5efe05 | 5890 | */ |
5d4dfddd | 5891 | if (!(sd->flags & SD_SHARE_CPUCAPACITY)) |
9d5efe05 SV |
5892 | return 0; |
5893 | ||
5894 | /* | |
63b2ca30 | 5895 | * If ~90% of the cpu_capacity is still there, we're good. |
9d5efe05 | 5896 | */ |
63b2ca30 | 5897 | if (group->sgc->capacity * 32 > group->sgc->capacity_orig * 29) |
9d5efe05 SV |
5898 | return 1; |
5899 | ||
5900 | return 0; | |
5901 | } | |
5902 | ||
30ce5dab PZ |
5903 | /* |
5904 | * Group imbalance indicates (and tries to solve) the problem where balancing | |
5905 | * groups is inadequate due to tsk_cpus_allowed() constraints. | |
5906 | * | |
5907 | * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a | |
5908 | * cpumask covering 1 cpu of the first group and 3 cpus of the second group. | |
5909 | * Something like: | |
5910 | * | |
5911 | * { 0 1 2 3 } { 4 5 6 7 } | |
5912 | * * * * * | |
5913 | * | |
5914 | * If we were to balance group-wise we'd place two tasks in the first group and | |
5915 | * two tasks in the second group. Clearly this is undesired as it will overload | |
5916 | * cpu 3 and leave one of the cpus in the second group unused. | |
5917 | * | |
5918 | * The current solution to this issue is detecting the skew in the first group | |
6263322c PZ |
5919 | * by noticing the lower domain failed to reach balance and had difficulty |
5920 | * moving tasks due to affinity constraints. | |
30ce5dab PZ |
5921 | * |
5922 | * When this is so detected; this group becomes a candidate for busiest; see | |
ed1b7732 | 5923 | * update_sd_pick_busiest(). And calculate_imbalance() and |
6263322c | 5924 | * find_busiest_group() avoid some of the usual balance conditions to allow it |
30ce5dab PZ |
5925 | * to create an effective group imbalance. |
5926 | * | |
5927 | * This is a somewhat tricky proposition since the next run might not find the | |
5928 | * group imbalance and decide the groups need to be balanced again. A most | |
5929 | * subtle and fragile situation. | |
5930 | */ | |
5931 | ||
6263322c | 5932 | static inline int sg_imbalanced(struct sched_group *group) |
30ce5dab | 5933 | { |
63b2ca30 | 5934 | return group->sgc->imbalance; |
30ce5dab PZ |
5935 | } |
5936 | ||
b37d9316 | 5937 | /* |
0fedc6c8 | 5938 | * Compute the group capacity factor. |
b37d9316 | 5939 | * |
ced549fa | 5940 | * Avoid the issue where N*frac(smt_capacity) >= 1 creates 'phantom' cores by |
c61037e9 | 5941 | * first dividing out the smt factor and computing the actual number of cores |
63b2ca30 | 5942 | * and limit unit capacity with that. |
b37d9316 | 5943 | */ |
0fedc6c8 | 5944 | static inline int sg_capacity_factor(struct lb_env *env, struct sched_group *group) |
b37d9316 | 5945 | { |
0fedc6c8 | 5946 | unsigned int capacity_factor, smt, cpus; |
63b2ca30 | 5947 | unsigned int capacity, capacity_orig; |
c61037e9 | 5948 | |
63b2ca30 NP |
5949 | capacity = group->sgc->capacity; |
5950 | capacity_orig = group->sgc->capacity_orig; | |
c61037e9 | 5951 | cpus = group->group_weight; |
b37d9316 | 5952 | |
63b2ca30 | 5953 | /* smt := ceil(cpus / capacity), assumes: 1 < smt_capacity < 2 */ |
ca8ce3d0 | 5954 | smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, capacity_orig); |
0fedc6c8 | 5955 | capacity_factor = cpus / smt; /* cores */ |
b37d9316 | 5956 | |
63b2ca30 | 5957 | capacity_factor = min_t(unsigned, |
ca8ce3d0 | 5958 | capacity_factor, DIV_ROUND_CLOSEST(capacity, SCHED_CAPACITY_SCALE)); |
0fedc6c8 NP |
5959 | if (!capacity_factor) |
5960 | capacity_factor = fix_small_capacity(env->sd, group); | |
b37d9316 | 5961 | |
0fedc6c8 | 5962 | return capacity_factor; |
b37d9316 PZ |
5963 | } |
5964 | ||
caeb178c RR |
5965 | static enum group_type |
5966 | group_classify(struct sched_group *group, struct sg_lb_stats *sgs) | |
5967 | { | |
5968 | if (sgs->sum_nr_running > sgs->group_capacity_factor) | |
5969 | return group_overloaded; | |
5970 | ||
5971 | if (sg_imbalanced(group)) | |
5972 | return group_imbalanced; | |
5973 | ||
5974 | return group_other; | |
5975 | } | |
5976 | ||
1e3c88bd PZ |
5977 | /** |
5978 | * update_sg_lb_stats - Update sched_group's statistics for load balancing. | |
cd96891d | 5979 | * @env: The load balancing environment. |
1e3c88bd | 5980 | * @group: sched_group whose statistics are to be updated. |
1e3c88bd | 5981 | * @load_idx: Load index of sched_domain of this_cpu for load calc. |
1e3c88bd | 5982 | * @local_group: Does group contain this_cpu. |
1e3c88bd | 5983 | * @sgs: variable to hold the statistics for this group. |
cd3bd4e6 | 5984 | * @overload: Indicate more than one runnable task for any CPU. |
1e3c88bd | 5985 | */ |
bd939f45 PZ |
5986 | static inline void update_sg_lb_stats(struct lb_env *env, |
5987 | struct sched_group *group, int load_idx, | |
4486edd1 TC |
5988 | int local_group, struct sg_lb_stats *sgs, |
5989 | bool *overload) | |
1e3c88bd | 5990 | { |
30ce5dab | 5991 | unsigned long load; |
bd939f45 | 5992 | int i; |
1e3c88bd | 5993 | |
b72ff13c PZ |
5994 | memset(sgs, 0, sizeof(*sgs)); |
5995 | ||
b9403130 | 5996 | for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
1e3c88bd PZ |
5997 | struct rq *rq = cpu_rq(i); |
5998 | ||
1e3c88bd | 5999 | /* Bias balancing toward cpus of our domain */ |
6263322c | 6000 | if (local_group) |
04f733b4 | 6001 | load = target_load(i, load_idx); |
6263322c | 6002 | else |
1e3c88bd | 6003 | load = source_load(i, load_idx); |
1e3c88bd PZ |
6004 | |
6005 | sgs->group_load += load; | |
380c9077 | 6006 | sgs->sum_nr_running += rq->nr_running; |
4486edd1 TC |
6007 | |
6008 | if (rq->nr_running > 1) | |
6009 | *overload = true; | |
6010 | ||
0ec8aa00 PZ |
6011 | #ifdef CONFIG_NUMA_BALANCING |
6012 | sgs->nr_numa_running += rq->nr_numa_running; | |
6013 | sgs->nr_preferred_running += rq->nr_preferred_running; | |
6014 | #endif | |
1e3c88bd | 6015 | sgs->sum_weighted_load += weighted_cpuload(i); |
aae6d3dd SS |
6016 | if (idle_cpu(i)) |
6017 | sgs->idle_cpus++; | |
1e3c88bd PZ |
6018 | } |
6019 | ||
63b2ca30 NP |
6020 | /* Adjust by relative CPU capacity of the group */ |
6021 | sgs->group_capacity = group->sgc->capacity; | |
ca8ce3d0 | 6022 | sgs->avg_load = (sgs->group_load*SCHED_CAPACITY_SCALE) / sgs->group_capacity; |
1e3c88bd | 6023 | |
dd5feea1 | 6024 | if (sgs->sum_nr_running) |
38d0f770 | 6025 | sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; |
1e3c88bd | 6026 | |
aae6d3dd | 6027 | sgs->group_weight = group->group_weight; |
0fedc6c8 | 6028 | sgs->group_capacity_factor = sg_capacity_factor(env, group); |
caeb178c | 6029 | sgs->group_type = group_classify(group, sgs); |
b37d9316 | 6030 | |
0fedc6c8 | 6031 | if (sgs->group_capacity_factor > sgs->sum_nr_running) |
1b6a7495 | 6032 | sgs->group_has_free_capacity = 1; |
1e3c88bd PZ |
6033 | } |
6034 | ||
532cb4c4 MN |
6035 | /** |
6036 | * update_sd_pick_busiest - return 1 on busiest group | |
cd96891d | 6037 | * @env: The load balancing environment. |
532cb4c4 MN |
6038 | * @sds: sched_domain statistics |
6039 | * @sg: sched_group candidate to be checked for being the busiest | |
b6b12294 | 6040 | * @sgs: sched_group statistics |
532cb4c4 MN |
6041 | * |
6042 | * Determine if @sg is a busier group than the previously selected | |
6043 | * busiest group. | |
e69f6186 YB |
6044 | * |
6045 | * Return: %true if @sg is a busier group than the previously selected | |
6046 | * busiest group. %false otherwise. | |
532cb4c4 | 6047 | */ |
bd939f45 | 6048 | static bool update_sd_pick_busiest(struct lb_env *env, |
532cb4c4 MN |
6049 | struct sd_lb_stats *sds, |
6050 | struct sched_group *sg, | |
bd939f45 | 6051 | struct sg_lb_stats *sgs) |
532cb4c4 | 6052 | { |
caeb178c | 6053 | struct sg_lb_stats *busiest = &sds->busiest_stat; |
532cb4c4 | 6054 | |
caeb178c | 6055 | if (sgs->group_type > busiest->group_type) |
532cb4c4 MN |
6056 | return true; |
6057 | ||
caeb178c RR |
6058 | if (sgs->group_type < busiest->group_type) |
6059 | return false; | |
6060 | ||
6061 | if (sgs->avg_load <= busiest->avg_load) | |
6062 | return false; | |
6063 | ||
6064 | /* This is the busiest node in its class. */ | |
6065 | if (!(env->sd->flags & SD_ASYM_PACKING)) | |
532cb4c4 MN |
6066 | return true; |
6067 | ||
6068 | /* | |
6069 | * ASYM_PACKING needs to move all the work to the lowest | |
6070 | * numbered CPUs in the group, therefore mark all groups | |
6071 | * higher than ourself as busy. | |
6072 | */ | |
caeb178c | 6073 | if (sgs->sum_nr_running && env->dst_cpu < group_first_cpu(sg)) { |
532cb4c4 MN |
6074 | if (!sds->busiest) |
6075 | return true; | |
6076 | ||
6077 | if (group_first_cpu(sds->busiest) > group_first_cpu(sg)) | |
6078 | return true; | |
6079 | } | |
6080 | ||
6081 | return false; | |
6082 | } | |
6083 | ||
0ec8aa00 PZ |
6084 | #ifdef CONFIG_NUMA_BALANCING |
6085 | static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) | |
6086 | { | |
6087 | if (sgs->sum_nr_running > sgs->nr_numa_running) | |
6088 | return regular; | |
6089 | if (sgs->sum_nr_running > sgs->nr_preferred_running) | |
6090 | return remote; | |
6091 | return all; | |
6092 | } | |
6093 | ||
6094 | static inline enum fbq_type fbq_classify_rq(struct rq *rq) | |
6095 | { | |
6096 | if (rq->nr_running > rq->nr_numa_running) | |
6097 | return regular; | |
6098 | if (rq->nr_running > rq->nr_preferred_running) | |
6099 | return remote; | |
6100 | return all; | |
6101 | } | |
6102 | #else | |
6103 | static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) | |
6104 | { | |
6105 | return all; | |
6106 | } | |
6107 | ||
6108 | static inline enum fbq_type fbq_classify_rq(struct rq *rq) | |
6109 | { | |
6110 | return regular; | |
6111 | } | |
6112 | #endif /* CONFIG_NUMA_BALANCING */ | |
6113 | ||
1e3c88bd | 6114 | /** |
461819ac | 6115 | * update_sd_lb_stats - Update sched_domain's statistics for load balancing. |
cd96891d | 6116 | * @env: The load balancing environment. |
1e3c88bd PZ |
6117 | * @sds: variable to hold the statistics for this sched_domain. |
6118 | */ | |
0ec8aa00 | 6119 | static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds) |
1e3c88bd | 6120 | { |
bd939f45 PZ |
6121 | struct sched_domain *child = env->sd->child; |
6122 | struct sched_group *sg = env->sd->groups; | |
56cf515b | 6123 | struct sg_lb_stats tmp_sgs; |
1e3c88bd | 6124 | int load_idx, prefer_sibling = 0; |
4486edd1 | 6125 | bool overload = false; |
1e3c88bd PZ |
6126 | |
6127 | if (child && child->flags & SD_PREFER_SIBLING) | |
6128 | prefer_sibling = 1; | |
6129 | ||
bd939f45 | 6130 | load_idx = get_sd_load_idx(env->sd, env->idle); |
1e3c88bd PZ |
6131 | |
6132 | do { | |
56cf515b | 6133 | struct sg_lb_stats *sgs = &tmp_sgs; |
1e3c88bd PZ |
6134 | int local_group; |
6135 | ||
bd939f45 | 6136 | local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg)); |
56cf515b JK |
6137 | if (local_group) { |
6138 | sds->local = sg; | |
6139 | sgs = &sds->local_stat; | |
b72ff13c PZ |
6140 | |
6141 | if (env->idle != CPU_NEWLY_IDLE || | |
63b2ca30 NP |
6142 | time_after_eq(jiffies, sg->sgc->next_update)) |
6143 | update_group_capacity(env->sd, env->dst_cpu); | |
56cf515b | 6144 | } |
1e3c88bd | 6145 | |
4486edd1 TC |
6146 | update_sg_lb_stats(env, sg, load_idx, local_group, sgs, |
6147 | &overload); | |
1e3c88bd | 6148 | |
b72ff13c PZ |
6149 | if (local_group) |
6150 | goto next_group; | |
6151 | ||
1e3c88bd PZ |
6152 | /* |
6153 | * In case the child domain prefers tasks go to siblings | |
0fedc6c8 | 6154 | * first, lower the sg capacity factor to one so that we'll try |
75dd321d NR |
6155 | * and move all the excess tasks away. We lower the capacity |
6156 | * of a group only if the local group has the capacity to fit | |
0fedc6c8 | 6157 | * these excess tasks, i.e. nr_running < group_capacity_factor. The |
75dd321d NR |
6158 | * extra check prevents the case where you always pull from the |
6159 | * heaviest group when it is already under-utilized (possible | |
6160 | * with a large weight task outweighs the tasks on the system). | |
1e3c88bd | 6161 | */ |
b72ff13c | 6162 | if (prefer_sibling && sds->local && |
1b6a7495 | 6163 | sds->local_stat.group_has_free_capacity) |
0fedc6c8 | 6164 | sgs->group_capacity_factor = min(sgs->group_capacity_factor, 1U); |
1e3c88bd | 6165 | |
b72ff13c | 6166 | if (update_sd_pick_busiest(env, sds, sg, sgs)) { |
532cb4c4 | 6167 | sds->busiest = sg; |
56cf515b | 6168 | sds->busiest_stat = *sgs; |
1e3c88bd PZ |
6169 | } |
6170 | ||
b72ff13c PZ |
6171 | next_group: |
6172 | /* Now, start updating sd_lb_stats */ | |
6173 | sds->total_load += sgs->group_load; | |
63b2ca30 | 6174 | sds->total_capacity += sgs->group_capacity; |
b72ff13c | 6175 | |
532cb4c4 | 6176 | sg = sg->next; |
bd939f45 | 6177 | } while (sg != env->sd->groups); |
0ec8aa00 PZ |
6178 | |
6179 | if (env->sd->flags & SD_NUMA) | |
6180 | env->fbq_type = fbq_classify_group(&sds->busiest_stat); | |
4486edd1 TC |
6181 | |
6182 | if (!env->sd->parent) { | |
6183 | /* update overload indicator if we are at root domain */ | |
6184 | if (env->dst_rq->rd->overload != overload) | |
6185 | env->dst_rq->rd->overload = overload; | |
6186 | } | |
6187 | ||
532cb4c4 MN |
6188 | } |
6189 | ||
532cb4c4 MN |
6190 | /** |
6191 | * check_asym_packing - Check to see if the group is packed into the | |
6192 | * sched doman. | |
6193 | * | |
6194 | * This is primarily intended to used at the sibling level. Some | |
6195 | * cores like POWER7 prefer to use lower numbered SMT threads. In the | |
6196 | * case of POWER7, it can move to lower SMT modes only when higher | |
6197 | * threads are idle. When in lower SMT modes, the threads will | |
6198 | * perform better since they share less core resources. Hence when we | |
6199 | * have idle threads, we want them to be the higher ones. | |
6200 | * | |
6201 | * This packing function is run on idle threads. It checks to see if | |
6202 | * the busiest CPU in this domain (core in the P7 case) has a higher | |
6203 | * CPU number than the packing function is being run on. Here we are | |
6204 | * assuming lower CPU number will be equivalent to lower a SMT thread | |
6205 | * number. | |
6206 | * | |
e69f6186 | 6207 | * Return: 1 when packing is required and a task should be moved to |
b6b12294 MN |
6208 | * this CPU. The amount of the imbalance is returned in *imbalance. |
6209 | * | |
cd96891d | 6210 | * @env: The load balancing environment. |
532cb4c4 | 6211 | * @sds: Statistics of the sched_domain which is to be packed |
532cb4c4 | 6212 | */ |
bd939f45 | 6213 | static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) |
532cb4c4 MN |
6214 | { |
6215 | int busiest_cpu; | |
6216 | ||
bd939f45 | 6217 | if (!(env->sd->flags & SD_ASYM_PACKING)) |
532cb4c4 MN |
6218 | return 0; |
6219 | ||
6220 | if (!sds->busiest) | |
6221 | return 0; | |
6222 | ||
6223 | busiest_cpu = group_first_cpu(sds->busiest); | |
bd939f45 | 6224 | if (env->dst_cpu > busiest_cpu) |
532cb4c4 MN |
6225 | return 0; |
6226 | ||
bd939f45 | 6227 | env->imbalance = DIV_ROUND_CLOSEST( |
63b2ca30 | 6228 | sds->busiest_stat.avg_load * sds->busiest_stat.group_capacity, |
ca8ce3d0 | 6229 | SCHED_CAPACITY_SCALE); |
bd939f45 | 6230 | |
532cb4c4 | 6231 | return 1; |
1e3c88bd PZ |
6232 | } |
6233 | ||
6234 | /** | |
6235 | * fix_small_imbalance - Calculate the minor imbalance that exists | |
6236 | * amongst the groups of a sched_domain, during | |
6237 | * load balancing. | |
cd96891d | 6238 | * @env: The load balancing environment. |
1e3c88bd | 6239 | * @sds: Statistics of the sched_domain whose imbalance is to be calculated. |
1e3c88bd | 6240 | */ |
bd939f45 PZ |
6241 | static inline |
6242 | void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) | |
1e3c88bd | 6243 | { |
63b2ca30 | 6244 | unsigned long tmp, capa_now = 0, capa_move = 0; |
1e3c88bd | 6245 | unsigned int imbn = 2; |
dd5feea1 | 6246 | unsigned long scaled_busy_load_per_task; |
56cf515b | 6247 | struct sg_lb_stats *local, *busiest; |
1e3c88bd | 6248 | |
56cf515b JK |
6249 | local = &sds->local_stat; |
6250 | busiest = &sds->busiest_stat; | |
1e3c88bd | 6251 | |
56cf515b JK |
6252 | if (!local->sum_nr_running) |
6253 | local->load_per_task = cpu_avg_load_per_task(env->dst_cpu); | |
6254 | else if (busiest->load_per_task > local->load_per_task) | |
6255 | imbn = 1; | |
dd5feea1 | 6256 | |
56cf515b | 6257 | scaled_busy_load_per_task = |
ca8ce3d0 | 6258 | (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
63b2ca30 | 6259 | busiest->group_capacity; |
56cf515b | 6260 | |
3029ede3 VD |
6261 | if (busiest->avg_load + scaled_busy_load_per_task >= |
6262 | local->avg_load + (scaled_busy_load_per_task * imbn)) { | |
56cf515b | 6263 | env->imbalance = busiest->load_per_task; |
1e3c88bd PZ |
6264 | return; |
6265 | } | |
6266 | ||
6267 | /* | |
6268 | * OK, we don't have enough imbalance to justify moving tasks, | |
ced549fa | 6269 | * however we may be able to increase total CPU capacity used by |
1e3c88bd PZ |
6270 | * moving them. |
6271 | */ | |
6272 | ||
63b2ca30 | 6273 | capa_now += busiest->group_capacity * |
56cf515b | 6274 | min(busiest->load_per_task, busiest->avg_load); |
63b2ca30 | 6275 | capa_now += local->group_capacity * |
56cf515b | 6276 | min(local->load_per_task, local->avg_load); |
ca8ce3d0 | 6277 | capa_now /= SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
6278 | |
6279 | /* Amount of load we'd subtract */ | |
a2cd4260 | 6280 | if (busiest->avg_load > scaled_busy_load_per_task) { |
63b2ca30 | 6281 | capa_move += busiest->group_capacity * |
56cf515b | 6282 | min(busiest->load_per_task, |
a2cd4260 | 6283 | busiest->avg_load - scaled_busy_load_per_task); |
56cf515b | 6284 | } |
1e3c88bd PZ |
6285 | |
6286 | /* Amount of load we'd add */ | |
63b2ca30 | 6287 | if (busiest->avg_load * busiest->group_capacity < |
ca8ce3d0 | 6288 | busiest->load_per_task * SCHED_CAPACITY_SCALE) { |
63b2ca30 NP |
6289 | tmp = (busiest->avg_load * busiest->group_capacity) / |
6290 | local->group_capacity; | |
56cf515b | 6291 | } else { |
ca8ce3d0 | 6292 | tmp = (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
63b2ca30 | 6293 | local->group_capacity; |
56cf515b | 6294 | } |
63b2ca30 | 6295 | capa_move += local->group_capacity * |
3ae11c90 | 6296 | min(local->load_per_task, local->avg_load + tmp); |
ca8ce3d0 | 6297 | capa_move /= SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
6298 | |
6299 | /* Move if we gain throughput */ | |
63b2ca30 | 6300 | if (capa_move > capa_now) |
56cf515b | 6301 | env->imbalance = busiest->load_per_task; |
1e3c88bd PZ |
6302 | } |
6303 | ||
6304 | /** | |
6305 | * calculate_imbalance - Calculate the amount of imbalance present within the | |
6306 | * groups of a given sched_domain during load balance. | |
bd939f45 | 6307 | * @env: load balance environment |
1e3c88bd | 6308 | * @sds: statistics of the sched_domain whose imbalance is to be calculated. |
1e3c88bd | 6309 | */ |
bd939f45 | 6310 | static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds) |
1e3c88bd | 6311 | { |
dd5feea1 | 6312 | unsigned long max_pull, load_above_capacity = ~0UL; |
56cf515b JK |
6313 | struct sg_lb_stats *local, *busiest; |
6314 | ||
6315 | local = &sds->local_stat; | |
56cf515b | 6316 | busiest = &sds->busiest_stat; |
dd5feea1 | 6317 | |
caeb178c | 6318 | if (busiest->group_type == group_imbalanced) { |
30ce5dab PZ |
6319 | /* |
6320 | * In the group_imb case we cannot rely on group-wide averages | |
6321 | * to ensure cpu-load equilibrium, look at wider averages. XXX | |
6322 | */ | |
56cf515b JK |
6323 | busiest->load_per_task = |
6324 | min(busiest->load_per_task, sds->avg_load); | |
dd5feea1 SS |
6325 | } |
6326 | ||
1e3c88bd PZ |
6327 | /* |
6328 | * In the presence of smp nice balancing, certain scenarios can have | |
6329 | * max load less than avg load(as we skip the groups at or below | |
ced549fa | 6330 | * its cpu_capacity, while calculating max_load..) |
1e3c88bd | 6331 | */ |
b1885550 VD |
6332 | if (busiest->avg_load <= sds->avg_load || |
6333 | local->avg_load >= sds->avg_load) { | |
bd939f45 PZ |
6334 | env->imbalance = 0; |
6335 | return fix_small_imbalance(env, sds); | |
1e3c88bd PZ |
6336 | } |
6337 | ||
9a5d9ba6 PZ |
6338 | /* |
6339 | * If there aren't any idle cpus, avoid creating some. | |
6340 | */ | |
6341 | if (busiest->group_type == group_overloaded && | |
6342 | local->group_type == group_overloaded) { | |
56cf515b | 6343 | load_above_capacity = |
0fedc6c8 | 6344 | (busiest->sum_nr_running - busiest->group_capacity_factor); |
dd5feea1 | 6345 | |
ca8ce3d0 | 6346 | load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_CAPACITY_SCALE); |
63b2ca30 | 6347 | load_above_capacity /= busiest->group_capacity; |
dd5feea1 SS |
6348 | } |
6349 | ||
6350 | /* | |
6351 | * We're trying to get all the cpus to the average_load, so we don't | |
6352 | * want to push ourselves above the average load, nor do we wish to | |
6353 | * reduce the max loaded cpu below the average load. At the same time, | |
6354 | * we also don't want to reduce the group load below the group capacity | |
6355 | * (so that we can implement power-savings policies etc). Thus we look | |
6356 | * for the minimum possible imbalance. | |
dd5feea1 | 6357 | */ |
30ce5dab | 6358 | max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity); |
1e3c88bd PZ |
6359 | |
6360 | /* How much load to actually move to equalise the imbalance */ | |
56cf515b | 6361 | env->imbalance = min( |
63b2ca30 NP |
6362 | max_pull * busiest->group_capacity, |
6363 | (sds->avg_load - local->avg_load) * local->group_capacity | |
ca8ce3d0 | 6364 | ) / SCHED_CAPACITY_SCALE; |
1e3c88bd PZ |
6365 | |
6366 | /* | |
6367 | * if *imbalance is less than the average load per runnable task | |
25985edc | 6368 | * there is no guarantee that any tasks will be moved so we'll have |
1e3c88bd PZ |
6369 | * a think about bumping its value to force at least one task to be |
6370 | * moved | |
6371 | */ | |
56cf515b | 6372 | if (env->imbalance < busiest->load_per_task) |
bd939f45 | 6373 | return fix_small_imbalance(env, sds); |
1e3c88bd | 6374 | } |
fab47622 | 6375 | |
1e3c88bd PZ |
6376 | /******* find_busiest_group() helpers end here *********************/ |
6377 | ||
6378 | /** | |
6379 | * find_busiest_group - Returns the busiest group within the sched_domain | |
6380 | * if there is an imbalance. If there isn't an imbalance, and | |
6381 | * the user has opted for power-savings, it returns a group whose | |
6382 | * CPUs can be put to idle by rebalancing those tasks elsewhere, if | |
6383 | * such a group exists. | |
6384 | * | |
6385 | * Also calculates the amount of weighted load which should be moved | |
6386 | * to restore balance. | |
6387 | * | |
cd96891d | 6388 | * @env: The load balancing environment. |
1e3c88bd | 6389 | * |
e69f6186 | 6390 | * Return: - The busiest group if imbalance exists. |
1e3c88bd PZ |
6391 | * - If no imbalance and user has opted for power-savings balance, |
6392 | * return the least loaded group whose CPUs can be | |
6393 | * put to idle by rebalancing its tasks onto our group. | |
6394 | */ | |
56cf515b | 6395 | static struct sched_group *find_busiest_group(struct lb_env *env) |
1e3c88bd | 6396 | { |
56cf515b | 6397 | struct sg_lb_stats *local, *busiest; |
1e3c88bd PZ |
6398 | struct sd_lb_stats sds; |
6399 | ||
147c5fc2 | 6400 | init_sd_lb_stats(&sds); |
1e3c88bd PZ |
6401 | |
6402 | /* | |
6403 | * Compute the various statistics relavent for load balancing at | |
6404 | * this level. | |
6405 | */ | |
23f0d209 | 6406 | update_sd_lb_stats(env, &sds); |
56cf515b JK |
6407 | local = &sds.local_stat; |
6408 | busiest = &sds.busiest_stat; | |
1e3c88bd | 6409 | |
bd939f45 PZ |
6410 | if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) && |
6411 | check_asym_packing(env, &sds)) | |
532cb4c4 MN |
6412 | return sds.busiest; |
6413 | ||
cc57aa8f | 6414 | /* There is no busy sibling group to pull tasks from */ |
56cf515b | 6415 | if (!sds.busiest || busiest->sum_nr_running == 0) |
1e3c88bd PZ |
6416 | goto out_balanced; |
6417 | ||
ca8ce3d0 NP |
6418 | sds.avg_load = (SCHED_CAPACITY_SCALE * sds.total_load) |
6419 | / sds.total_capacity; | |
b0432d8f | 6420 | |
866ab43e PZ |
6421 | /* |
6422 | * If the busiest group is imbalanced the below checks don't | |
30ce5dab | 6423 | * work because they assume all things are equal, which typically |
866ab43e PZ |
6424 | * isn't true due to cpus_allowed constraints and the like. |
6425 | */ | |
caeb178c | 6426 | if (busiest->group_type == group_imbalanced) |
866ab43e PZ |
6427 | goto force_balance; |
6428 | ||
cc57aa8f | 6429 | /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */ |
1b6a7495 NP |
6430 | if (env->idle == CPU_NEWLY_IDLE && local->group_has_free_capacity && |
6431 | !busiest->group_has_free_capacity) | |
fab47622 NR |
6432 | goto force_balance; |
6433 | ||
cc57aa8f PZ |
6434 | /* |
6435 | * If the local group is more busy than the selected busiest group | |
6436 | * don't try and pull any tasks. | |
6437 | */ | |
56cf515b | 6438 | if (local->avg_load >= busiest->avg_load) |
1e3c88bd PZ |
6439 | goto out_balanced; |
6440 | ||
cc57aa8f PZ |
6441 | /* |
6442 | * Don't pull any tasks if this group is already above the domain | |
6443 | * average load. | |
6444 | */ | |
56cf515b | 6445 | if (local->avg_load >= sds.avg_load) |
1e3c88bd PZ |
6446 | goto out_balanced; |
6447 | ||
bd939f45 | 6448 | if (env->idle == CPU_IDLE) { |
aae6d3dd SS |
6449 | /* |
6450 | * This cpu is idle. If the busiest group load doesn't | |
6451 | * have more tasks than the number of available cpu's and | |
6452 | * there is no imbalance between this and busiest group | |
6453 | * wrt to idle cpu's, it is balanced. | |
6454 | */ | |
56cf515b JK |
6455 | if ((local->idle_cpus < busiest->idle_cpus) && |
6456 | busiest->sum_nr_running <= busiest->group_weight) | |
aae6d3dd | 6457 | goto out_balanced; |
c186fafe PZ |
6458 | } else { |
6459 | /* | |
6460 | * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use | |
6461 | * imbalance_pct to be conservative. | |
6462 | */ | |
56cf515b JK |
6463 | if (100 * busiest->avg_load <= |
6464 | env->sd->imbalance_pct * local->avg_load) | |
c186fafe | 6465 | goto out_balanced; |
aae6d3dd | 6466 | } |
1e3c88bd | 6467 | |
fab47622 | 6468 | force_balance: |
1e3c88bd | 6469 | /* Looks like there is an imbalance. Compute it */ |
bd939f45 | 6470 | calculate_imbalance(env, &sds); |
1e3c88bd PZ |
6471 | return sds.busiest; |
6472 | ||
6473 | out_balanced: | |
bd939f45 | 6474 | env->imbalance = 0; |
1e3c88bd PZ |
6475 | return NULL; |
6476 | } | |
6477 | ||
6478 | /* | |
6479 | * find_busiest_queue - find the busiest runqueue among the cpus in group. | |
6480 | */ | |
bd939f45 | 6481 | static struct rq *find_busiest_queue(struct lb_env *env, |
b9403130 | 6482 | struct sched_group *group) |
1e3c88bd PZ |
6483 | { |
6484 | struct rq *busiest = NULL, *rq; | |
ced549fa | 6485 | unsigned long busiest_load = 0, busiest_capacity = 1; |
1e3c88bd PZ |
6486 | int i; |
6487 | ||
6906a408 | 6488 | for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
ced549fa | 6489 | unsigned long capacity, capacity_factor, wl; |
0ec8aa00 PZ |
6490 | enum fbq_type rt; |
6491 | ||
6492 | rq = cpu_rq(i); | |
6493 | rt = fbq_classify_rq(rq); | |
1e3c88bd | 6494 | |
0ec8aa00 PZ |
6495 | /* |
6496 | * We classify groups/runqueues into three groups: | |
6497 | * - regular: there are !numa tasks | |
6498 | * - remote: there are numa tasks that run on the 'wrong' node | |
6499 | * - all: there is no distinction | |
6500 | * | |
6501 | * In order to avoid migrating ideally placed numa tasks, | |
6502 | * ignore those when there's better options. | |
6503 | * | |
6504 | * If we ignore the actual busiest queue to migrate another | |
6505 | * task, the next balance pass can still reduce the busiest | |
6506 | * queue by moving tasks around inside the node. | |
6507 | * | |
6508 | * If we cannot move enough load due to this classification | |
6509 | * the next pass will adjust the group classification and | |
6510 | * allow migration of more tasks. | |
6511 | * | |
6512 | * Both cases only affect the total convergence complexity. | |
6513 | */ | |
6514 | if (rt > env->fbq_type) | |
6515 | continue; | |
6516 | ||
ced549fa | 6517 | capacity = capacity_of(i); |
ca8ce3d0 | 6518 | capacity_factor = DIV_ROUND_CLOSEST(capacity, SCHED_CAPACITY_SCALE); |
0fedc6c8 NP |
6519 | if (!capacity_factor) |
6520 | capacity_factor = fix_small_capacity(env->sd, group); | |
9d5efe05 | 6521 | |
6e40f5bb | 6522 | wl = weighted_cpuload(i); |
1e3c88bd | 6523 | |
6e40f5bb TG |
6524 | /* |
6525 | * When comparing with imbalance, use weighted_cpuload() | |
ced549fa | 6526 | * which is not scaled with the cpu capacity. |
6e40f5bb | 6527 | */ |
0fedc6c8 | 6528 | if (capacity_factor && rq->nr_running == 1 && wl > env->imbalance) |
1e3c88bd PZ |
6529 | continue; |
6530 | ||
6e40f5bb TG |
6531 | /* |
6532 | * For the load comparisons with the other cpu's, consider | |
ced549fa NP |
6533 | * the weighted_cpuload() scaled with the cpu capacity, so |
6534 | * that the load can be moved away from the cpu that is | |
6535 | * potentially running at a lower capacity. | |
95a79b80 | 6536 | * |
ced549fa | 6537 | * Thus we're looking for max(wl_i / capacity_i), crosswise |
95a79b80 | 6538 | * multiplication to rid ourselves of the division works out |
ced549fa NP |
6539 | * to: wl_i * capacity_j > wl_j * capacity_i; where j is |
6540 | * our previous maximum. | |
6e40f5bb | 6541 | */ |
ced549fa | 6542 | if (wl * busiest_capacity > busiest_load * capacity) { |
95a79b80 | 6543 | busiest_load = wl; |
ced549fa | 6544 | busiest_capacity = capacity; |
1e3c88bd PZ |
6545 | busiest = rq; |
6546 | } | |
6547 | } | |
6548 | ||
6549 | return busiest; | |
6550 | } | |
6551 | ||
6552 | /* | |
6553 | * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but | |
6554 | * so long as it is large enough. | |
6555 | */ | |
6556 | #define MAX_PINNED_INTERVAL 512 | |
6557 | ||
6558 | /* Working cpumask for load_balance and load_balance_newidle. */ | |
e6252c3e | 6559 | DEFINE_PER_CPU(cpumask_var_t, load_balance_mask); |
1e3c88bd | 6560 | |
bd939f45 | 6561 | static int need_active_balance(struct lb_env *env) |
1af3ed3d | 6562 | { |
bd939f45 PZ |
6563 | struct sched_domain *sd = env->sd; |
6564 | ||
6565 | if (env->idle == CPU_NEWLY_IDLE) { | |
532cb4c4 MN |
6566 | |
6567 | /* | |
6568 | * ASYM_PACKING needs to force migrate tasks from busy but | |
6569 | * higher numbered CPUs in order to pack all tasks in the | |
6570 | * lowest numbered CPUs. | |
6571 | */ | |
bd939f45 | 6572 | if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu) |
532cb4c4 | 6573 | return 1; |
1af3ed3d PZ |
6574 | } |
6575 | ||
6576 | return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2); | |
6577 | } | |
6578 | ||
969c7921 TH |
6579 | static int active_load_balance_cpu_stop(void *data); |
6580 | ||
23f0d209 JK |
6581 | static int should_we_balance(struct lb_env *env) |
6582 | { | |
6583 | struct sched_group *sg = env->sd->groups; | |
6584 | struct cpumask *sg_cpus, *sg_mask; | |
6585 | int cpu, balance_cpu = -1; | |
6586 | ||
6587 | /* | |
6588 | * In the newly idle case, we will allow all the cpu's | |
6589 | * to do the newly idle load balance. | |
6590 | */ | |
6591 | if (env->idle == CPU_NEWLY_IDLE) | |
6592 | return 1; | |
6593 | ||
6594 | sg_cpus = sched_group_cpus(sg); | |
6595 | sg_mask = sched_group_mask(sg); | |
6596 | /* Try to find first idle cpu */ | |
6597 | for_each_cpu_and(cpu, sg_cpus, env->cpus) { | |
6598 | if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu)) | |
6599 | continue; | |
6600 | ||
6601 | balance_cpu = cpu; | |
6602 | break; | |
6603 | } | |
6604 | ||
6605 | if (balance_cpu == -1) | |
6606 | balance_cpu = group_balance_cpu(sg); | |
6607 | ||
6608 | /* | |
6609 | * First idle cpu or the first cpu(busiest) in this sched group | |
6610 | * is eligible for doing load balancing at this and above domains. | |
6611 | */ | |
b0cff9d8 | 6612 | return balance_cpu == env->dst_cpu; |
23f0d209 JK |
6613 | } |
6614 | ||
1e3c88bd PZ |
6615 | /* |
6616 | * Check this_cpu to ensure it is balanced within domain. Attempt to move | |
6617 | * tasks if there is an imbalance. | |
6618 | */ | |
6619 | static int load_balance(int this_cpu, struct rq *this_rq, | |
6620 | struct sched_domain *sd, enum cpu_idle_type idle, | |
23f0d209 | 6621 | int *continue_balancing) |
1e3c88bd | 6622 | { |
88b8dac0 | 6623 | int ld_moved, cur_ld_moved, active_balance = 0; |
6263322c | 6624 | struct sched_domain *sd_parent = sd->parent; |
1e3c88bd | 6625 | struct sched_group *group; |
1e3c88bd PZ |
6626 | struct rq *busiest; |
6627 | unsigned long flags; | |
e6252c3e | 6628 | struct cpumask *cpus = __get_cpu_var(load_balance_mask); |
1e3c88bd | 6629 | |
8e45cb54 PZ |
6630 | struct lb_env env = { |
6631 | .sd = sd, | |
ddcdf6e7 PZ |
6632 | .dst_cpu = this_cpu, |
6633 | .dst_rq = this_rq, | |
88b8dac0 | 6634 | .dst_grpmask = sched_group_cpus(sd->groups), |
8e45cb54 | 6635 | .idle = idle, |
eb95308e | 6636 | .loop_break = sched_nr_migrate_break, |
b9403130 | 6637 | .cpus = cpus, |
0ec8aa00 | 6638 | .fbq_type = all, |
163122b7 | 6639 | .tasks = LIST_HEAD_INIT(env.tasks), |
8e45cb54 PZ |
6640 | }; |
6641 | ||
cfc03118 JK |
6642 | /* |
6643 | * For NEWLY_IDLE load_balancing, we don't need to consider | |
6644 | * other cpus in our group | |
6645 | */ | |
e02e60c1 | 6646 | if (idle == CPU_NEWLY_IDLE) |
cfc03118 | 6647 | env.dst_grpmask = NULL; |
cfc03118 | 6648 | |
1e3c88bd PZ |
6649 | cpumask_copy(cpus, cpu_active_mask); |
6650 | ||
1e3c88bd PZ |
6651 | schedstat_inc(sd, lb_count[idle]); |
6652 | ||
6653 | redo: | |
23f0d209 JK |
6654 | if (!should_we_balance(&env)) { |
6655 | *continue_balancing = 0; | |
1e3c88bd | 6656 | goto out_balanced; |
23f0d209 | 6657 | } |
1e3c88bd | 6658 | |
23f0d209 | 6659 | group = find_busiest_group(&env); |
1e3c88bd PZ |
6660 | if (!group) { |
6661 | schedstat_inc(sd, lb_nobusyg[idle]); | |
6662 | goto out_balanced; | |
6663 | } | |
6664 | ||
b9403130 | 6665 | busiest = find_busiest_queue(&env, group); |
1e3c88bd PZ |
6666 | if (!busiest) { |
6667 | schedstat_inc(sd, lb_nobusyq[idle]); | |
6668 | goto out_balanced; | |
6669 | } | |
6670 | ||
78feefc5 | 6671 | BUG_ON(busiest == env.dst_rq); |
1e3c88bd | 6672 | |
bd939f45 | 6673 | schedstat_add(sd, lb_imbalance[idle], env.imbalance); |
1e3c88bd PZ |
6674 | |
6675 | ld_moved = 0; | |
6676 | if (busiest->nr_running > 1) { | |
6677 | /* | |
6678 | * Attempt to move tasks. If find_busiest_group has found | |
6679 | * an imbalance but busiest->nr_running <= 1, the group is | |
6680 | * still unbalanced. ld_moved simply stays zero, so it is | |
6681 | * correctly treated as an imbalance. | |
6682 | */ | |
8e45cb54 | 6683 | env.flags |= LBF_ALL_PINNED; |
c82513e5 PZ |
6684 | env.src_cpu = busiest->cpu; |
6685 | env.src_rq = busiest; | |
6686 | env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running); | |
8e45cb54 | 6687 | |
5d6523eb | 6688 | more_balance: |
163122b7 | 6689 | raw_spin_lock_irqsave(&busiest->lock, flags); |
88b8dac0 SV |
6690 | |
6691 | /* | |
6692 | * cur_ld_moved - load moved in current iteration | |
6693 | * ld_moved - cumulative load moved across iterations | |
6694 | */ | |
163122b7 KT |
6695 | cur_ld_moved = detach_tasks(&env); |
6696 | ||
6697 | /* | |
6698 | * We've detached some tasks from busiest_rq. Every | |
6699 | * task is masked "TASK_ON_RQ_MIGRATING", so we can safely | |
6700 | * unlock busiest->lock, and we are able to be sure | |
6701 | * that nobody can manipulate the tasks in parallel. | |
6702 | * See task_rq_lock() family for the details. | |
6703 | */ | |
6704 | ||
6705 | raw_spin_unlock(&busiest->lock); | |
6706 | ||
6707 | if (cur_ld_moved) { | |
6708 | attach_tasks(&env); | |
6709 | ld_moved += cur_ld_moved; | |
6710 | } | |
6711 | ||
1e3c88bd PZ |
6712 | local_irq_restore(flags); |
6713 | ||
6714 | /* | |
6715 | * some other cpu did the load balance for us. | |
6716 | */ | |
88b8dac0 SV |
6717 | if (cur_ld_moved && env.dst_cpu != smp_processor_id()) |
6718 | resched_cpu(env.dst_cpu); | |
6719 | ||
f1cd0858 JK |
6720 | if (env.flags & LBF_NEED_BREAK) { |
6721 | env.flags &= ~LBF_NEED_BREAK; | |
6722 | goto more_balance; | |
6723 | } | |
6724 | ||
88b8dac0 SV |
6725 | /* |
6726 | * Revisit (affine) tasks on src_cpu that couldn't be moved to | |
6727 | * us and move them to an alternate dst_cpu in our sched_group | |
6728 | * where they can run. The upper limit on how many times we | |
6729 | * iterate on same src_cpu is dependent on number of cpus in our | |
6730 | * sched_group. | |
6731 | * | |
6732 | * This changes load balance semantics a bit on who can move | |
6733 | * load to a given_cpu. In addition to the given_cpu itself | |
6734 | * (or a ilb_cpu acting on its behalf where given_cpu is | |
6735 | * nohz-idle), we now have balance_cpu in a position to move | |
6736 | * load to given_cpu. In rare situations, this may cause | |
6737 | * conflicts (balance_cpu and given_cpu/ilb_cpu deciding | |
6738 | * _independently_ and at _same_ time to move some load to | |
6739 | * given_cpu) causing exceess load to be moved to given_cpu. | |
6740 | * This however should not happen so much in practice and | |
6741 | * moreover subsequent load balance cycles should correct the | |
6742 | * excess load moved. | |
6743 | */ | |
6263322c | 6744 | if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) { |
88b8dac0 | 6745 | |
7aff2e3a VD |
6746 | /* Prevent to re-select dst_cpu via env's cpus */ |
6747 | cpumask_clear_cpu(env.dst_cpu, env.cpus); | |
6748 | ||
78feefc5 | 6749 | env.dst_rq = cpu_rq(env.new_dst_cpu); |
88b8dac0 | 6750 | env.dst_cpu = env.new_dst_cpu; |
6263322c | 6751 | env.flags &= ~LBF_DST_PINNED; |
88b8dac0 SV |
6752 | env.loop = 0; |
6753 | env.loop_break = sched_nr_migrate_break; | |
e02e60c1 | 6754 | |
88b8dac0 SV |
6755 | /* |
6756 | * Go back to "more_balance" rather than "redo" since we | |
6757 | * need to continue with same src_cpu. | |
6758 | */ | |
6759 | goto more_balance; | |
6760 | } | |
1e3c88bd | 6761 | |
6263322c PZ |
6762 | /* |
6763 | * We failed to reach balance because of affinity. | |
6764 | */ | |
6765 | if (sd_parent) { | |
63b2ca30 | 6766 | int *group_imbalance = &sd_parent->groups->sgc->imbalance; |
6263322c PZ |
6767 | |
6768 | if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) { | |
6769 | *group_imbalance = 1; | |
6770 | } else if (*group_imbalance) | |
6771 | *group_imbalance = 0; | |
6772 | } | |
6773 | ||
1e3c88bd | 6774 | /* All tasks on this runqueue were pinned by CPU affinity */ |
8e45cb54 | 6775 | if (unlikely(env.flags & LBF_ALL_PINNED)) { |
1e3c88bd | 6776 | cpumask_clear_cpu(cpu_of(busiest), cpus); |
bbf18b19 PN |
6777 | if (!cpumask_empty(cpus)) { |
6778 | env.loop = 0; | |
6779 | env.loop_break = sched_nr_migrate_break; | |
1e3c88bd | 6780 | goto redo; |
bbf18b19 | 6781 | } |
1e3c88bd PZ |
6782 | goto out_balanced; |
6783 | } | |
6784 | } | |
6785 | ||
6786 | if (!ld_moved) { | |
6787 | schedstat_inc(sd, lb_failed[idle]); | |
58b26c4c VP |
6788 | /* |
6789 | * Increment the failure counter only on periodic balance. | |
6790 | * We do not want newidle balance, which can be very | |
6791 | * frequent, pollute the failure counter causing | |
6792 | * excessive cache_hot migrations and active balances. | |
6793 | */ | |
6794 | if (idle != CPU_NEWLY_IDLE) | |
6795 | sd->nr_balance_failed++; | |
1e3c88bd | 6796 | |
bd939f45 | 6797 | if (need_active_balance(&env)) { |
1e3c88bd PZ |
6798 | raw_spin_lock_irqsave(&busiest->lock, flags); |
6799 | ||
969c7921 TH |
6800 | /* don't kick the active_load_balance_cpu_stop, |
6801 | * if the curr task on busiest cpu can't be | |
6802 | * moved to this_cpu | |
1e3c88bd PZ |
6803 | */ |
6804 | if (!cpumask_test_cpu(this_cpu, | |
fa17b507 | 6805 | tsk_cpus_allowed(busiest->curr))) { |
1e3c88bd PZ |
6806 | raw_spin_unlock_irqrestore(&busiest->lock, |
6807 | flags); | |
8e45cb54 | 6808 | env.flags |= LBF_ALL_PINNED; |
1e3c88bd PZ |
6809 | goto out_one_pinned; |
6810 | } | |
6811 | ||
969c7921 TH |
6812 | /* |
6813 | * ->active_balance synchronizes accesses to | |
6814 | * ->active_balance_work. Once set, it's cleared | |
6815 | * only after active load balance is finished. | |
6816 | */ | |
1e3c88bd PZ |
6817 | if (!busiest->active_balance) { |
6818 | busiest->active_balance = 1; | |
6819 | busiest->push_cpu = this_cpu; | |
6820 | active_balance = 1; | |
6821 | } | |
6822 | raw_spin_unlock_irqrestore(&busiest->lock, flags); | |
969c7921 | 6823 | |
bd939f45 | 6824 | if (active_balance) { |
969c7921 TH |
6825 | stop_one_cpu_nowait(cpu_of(busiest), |
6826 | active_load_balance_cpu_stop, busiest, | |
6827 | &busiest->active_balance_work); | |
bd939f45 | 6828 | } |
1e3c88bd PZ |
6829 | |
6830 | /* | |
6831 | * We've kicked active balancing, reset the failure | |
6832 | * counter. | |
6833 | */ | |
6834 | sd->nr_balance_failed = sd->cache_nice_tries+1; | |
6835 | } | |
6836 | } else | |
6837 | sd->nr_balance_failed = 0; | |
6838 | ||
6839 | if (likely(!active_balance)) { | |
6840 | /* We were unbalanced, so reset the balancing interval */ | |
6841 | sd->balance_interval = sd->min_interval; | |
6842 | } else { | |
6843 | /* | |
6844 | * If we've begun active balancing, start to back off. This | |
6845 | * case may not be covered by the all_pinned logic if there | |
6846 | * is only 1 task on the busy runqueue (because we don't call | |
163122b7 | 6847 | * detach_tasks). |
1e3c88bd PZ |
6848 | */ |
6849 | if (sd->balance_interval < sd->max_interval) | |
6850 | sd->balance_interval *= 2; | |
6851 | } | |
6852 | ||
1e3c88bd PZ |
6853 | goto out; |
6854 | ||
6855 | out_balanced: | |
6856 | schedstat_inc(sd, lb_balanced[idle]); | |
6857 | ||
6858 | sd->nr_balance_failed = 0; | |
6859 | ||
6860 | out_one_pinned: | |
6861 | /* tune up the balancing interval */ | |
8e45cb54 | 6862 | if (((env.flags & LBF_ALL_PINNED) && |
5b54b56b | 6863 | sd->balance_interval < MAX_PINNED_INTERVAL) || |
1e3c88bd PZ |
6864 | (sd->balance_interval < sd->max_interval)) |
6865 | sd->balance_interval *= 2; | |
6866 | ||
46e49b38 | 6867 | ld_moved = 0; |
1e3c88bd | 6868 | out: |
1e3c88bd PZ |
6869 | return ld_moved; |
6870 | } | |
6871 | ||
52a08ef1 JL |
6872 | static inline unsigned long |
6873 | get_sd_balance_interval(struct sched_domain *sd, int cpu_busy) | |
6874 | { | |
6875 | unsigned long interval = sd->balance_interval; | |
6876 | ||
6877 | if (cpu_busy) | |
6878 | interval *= sd->busy_factor; | |
6879 | ||
6880 | /* scale ms to jiffies */ | |
6881 | interval = msecs_to_jiffies(interval); | |
6882 | interval = clamp(interval, 1UL, max_load_balance_interval); | |
6883 | ||
6884 | return interval; | |
6885 | } | |
6886 | ||
6887 | static inline void | |
6888 | update_next_balance(struct sched_domain *sd, int cpu_busy, unsigned long *next_balance) | |
6889 | { | |
6890 | unsigned long interval, next; | |
6891 | ||
6892 | interval = get_sd_balance_interval(sd, cpu_busy); | |
6893 | next = sd->last_balance + interval; | |
6894 | ||
6895 | if (time_after(*next_balance, next)) | |
6896 | *next_balance = next; | |
6897 | } | |
6898 | ||
1e3c88bd PZ |
6899 | /* |
6900 | * idle_balance is called by schedule() if this_cpu is about to become | |
6901 | * idle. Attempts to pull tasks from other CPUs. | |
6902 | */ | |
6e83125c | 6903 | static int idle_balance(struct rq *this_rq) |
1e3c88bd | 6904 | { |
52a08ef1 JL |
6905 | unsigned long next_balance = jiffies + HZ; |
6906 | int this_cpu = this_rq->cpu; | |
1e3c88bd PZ |
6907 | struct sched_domain *sd; |
6908 | int pulled_task = 0; | |
9bd721c5 | 6909 | u64 curr_cost = 0; |
1e3c88bd | 6910 | |
6e83125c | 6911 | idle_enter_fair(this_rq); |
0e5b5337 | 6912 | |
6e83125c PZ |
6913 | /* |
6914 | * We must set idle_stamp _before_ calling idle_balance(), such that we | |
6915 | * measure the duration of idle_balance() as idle time. | |
6916 | */ | |
6917 | this_rq->idle_stamp = rq_clock(this_rq); | |
6918 | ||
4486edd1 TC |
6919 | if (this_rq->avg_idle < sysctl_sched_migration_cost || |
6920 | !this_rq->rd->overload) { | |
52a08ef1 JL |
6921 | rcu_read_lock(); |
6922 | sd = rcu_dereference_check_sched_domain(this_rq->sd); | |
6923 | if (sd) | |
6924 | update_next_balance(sd, 0, &next_balance); | |
6925 | rcu_read_unlock(); | |
6926 | ||
6e83125c | 6927 | goto out; |
52a08ef1 | 6928 | } |
1e3c88bd | 6929 | |
f492e12e PZ |
6930 | /* |
6931 | * Drop the rq->lock, but keep IRQ/preempt disabled. | |
6932 | */ | |
6933 | raw_spin_unlock(&this_rq->lock); | |
6934 | ||
48a16753 | 6935 | update_blocked_averages(this_cpu); |
dce840a0 | 6936 | rcu_read_lock(); |
1e3c88bd | 6937 | for_each_domain(this_cpu, sd) { |
23f0d209 | 6938 | int continue_balancing = 1; |
9bd721c5 | 6939 | u64 t0, domain_cost; |
1e3c88bd PZ |
6940 | |
6941 | if (!(sd->flags & SD_LOAD_BALANCE)) | |
6942 | continue; | |
6943 | ||
52a08ef1 JL |
6944 | if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) { |
6945 | update_next_balance(sd, 0, &next_balance); | |
9bd721c5 | 6946 | break; |
52a08ef1 | 6947 | } |
9bd721c5 | 6948 | |
f492e12e | 6949 | if (sd->flags & SD_BALANCE_NEWIDLE) { |
9bd721c5 JL |
6950 | t0 = sched_clock_cpu(this_cpu); |
6951 | ||
f492e12e | 6952 | pulled_task = load_balance(this_cpu, this_rq, |
23f0d209 JK |
6953 | sd, CPU_NEWLY_IDLE, |
6954 | &continue_balancing); | |
9bd721c5 JL |
6955 | |
6956 | domain_cost = sched_clock_cpu(this_cpu) - t0; | |
6957 | if (domain_cost > sd->max_newidle_lb_cost) | |
6958 | sd->max_newidle_lb_cost = domain_cost; | |
6959 | ||
6960 | curr_cost += domain_cost; | |
f492e12e | 6961 | } |
1e3c88bd | 6962 | |
52a08ef1 | 6963 | update_next_balance(sd, 0, &next_balance); |
39a4d9ca JL |
6964 | |
6965 | /* | |
6966 | * Stop searching for tasks to pull if there are | |
6967 | * now runnable tasks on this rq. | |
6968 | */ | |
6969 | if (pulled_task || this_rq->nr_running > 0) | |
1e3c88bd | 6970 | break; |
1e3c88bd | 6971 | } |
dce840a0 | 6972 | rcu_read_unlock(); |
f492e12e PZ |
6973 | |
6974 | raw_spin_lock(&this_rq->lock); | |
6975 | ||
0e5b5337 JL |
6976 | if (curr_cost > this_rq->max_idle_balance_cost) |
6977 | this_rq->max_idle_balance_cost = curr_cost; | |
6978 | ||
e5fc6611 | 6979 | /* |
0e5b5337 JL |
6980 | * While browsing the domains, we released the rq lock, a task could |
6981 | * have been enqueued in the meantime. Since we're not going idle, | |
6982 | * pretend we pulled a task. | |
e5fc6611 | 6983 | */ |
0e5b5337 | 6984 | if (this_rq->cfs.h_nr_running && !pulled_task) |
6e83125c | 6985 | pulled_task = 1; |
e5fc6611 | 6986 | |
52a08ef1 JL |
6987 | out: |
6988 | /* Move the next balance forward */ | |
6989 | if (time_after(this_rq->next_balance, next_balance)) | |
1e3c88bd | 6990 | this_rq->next_balance = next_balance; |
9bd721c5 | 6991 | |
e4aa358b | 6992 | /* Is there a task of a high priority class? */ |
46383648 | 6993 | if (this_rq->nr_running != this_rq->cfs.h_nr_running) |
e4aa358b KT |
6994 | pulled_task = -1; |
6995 | ||
6996 | if (pulled_task) { | |
6997 | idle_exit_fair(this_rq); | |
6e83125c | 6998 | this_rq->idle_stamp = 0; |
e4aa358b | 6999 | } |
6e83125c | 7000 | |
3c4017c1 | 7001 | return pulled_task; |
1e3c88bd PZ |
7002 | } |
7003 | ||
7004 | /* | |
969c7921 TH |
7005 | * active_load_balance_cpu_stop is run by cpu stopper. It pushes |
7006 | * running tasks off the busiest CPU onto idle CPUs. It requires at | |
7007 | * least 1 task to be running on each physical CPU where possible, and | |
7008 | * avoids physical / logical imbalances. | |
1e3c88bd | 7009 | */ |
969c7921 | 7010 | static int active_load_balance_cpu_stop(void *data) |
1e3c88bd | 7011 | { |
969c7921 TH |
7012 | struct rq *busiest_rq = data; |
7013 | int busiest_cpu = cpu_of(busiest_rq); | |
1e3c88bd | 7014 | int target_cpu = busiest_rq->push_cpu; |
969c7921 | 7015 | struct rq *target_rq = cpu_rq(target_cpu); |
1e3c88bd | 7016 | struct sched_domain *sd; |
e5673f28 | 7017 | struct task_struct *p = NULL; |
969c7921 TH |
7018 | |
7019 | raw_spin_lock_irq(&busiest_rq->lock); | |
7020 | ||
7021 | /* make sure the requested cpu hasn't gone down in the meantime */ | |
7022 | if (unlikely(busiest_cpu != smp_processor_id() || | |
7023 | !busiest_rq->active_balance)) | |
7024 | goto out_unlock; | |
1e3c88bd PZ |
7025 | |
7026 | /* Is there any task to move? */ | |
7027 | if (busiest_rq->nr_running <= 1) | |
969c7921 | 7028 | goto out_unlock; |
1e3c88bd PZ |
7029 | |
7030 | /* | |
7031 | * This condition is "impossible", if it occurs | |
7032 | * we need to fix it. Originally reported by | |
7033 | * Bjorn Helgaas on a 128-cpu setup. | |
7034 | */ | |
7035 | BUG_ON(busiest_rq == target_rq); | |
7036 | ||
1e3c88bd | 7037 | /* Search for an sd spanning us and the target CPU. */ |
dce840a0 | 7038 | rcu_read_lock(); |
1e3c88bd PZ |
7039 | for_each_domain(target_cpu, sd) { |
7040 | if ((sd->flags & SD_LOAD_BALANCE) && | |
7041 | cpumask_test_cpu(busiest_cpu, sched_domain_span(sd))) | |
7042 | break; | |
7043 | } | |
7044 | ||
7045 | if (likely(sd)) { | |
8e45cb54 PZ |
7046 | struct lb_env env = { |
7047 | .sd = sd, | |
ddcdf6e7 PZ |
7048 | .dst_cpu = target_cpu, |
7049 | .dst_rq = target_rq, | |
7050 | .src_cpu = busiest_rq->cpu, | |
7051 | .src_rq = busiest_rq, | |
8e45cb54 PZ |
7052 | .idle = CPU_IDLE, |
7053 | }; | |
7054 | ||
1e3c88bd PZ |
7055 | schedstat_inc(sd, alb_count); |
7056 | ||
e5673f28 KT |
7057 | p = detach_one_task(&env); |
7058 | if (p) | |
1e3c88bd PZ |
7059 | schedstat_inc(sd, alb_pushed); |
7060 | else | |
7061 | schedstat_inc(sd, alb_failed); | |
7062 | } | |
dce840a0 | 7063 | rcu_read_unlock(); |
969c7921 TH |
7064 | out_unlock: |
7065 | busiest_rq->active_balance = 0; | |
e5673f28 KT |
7066 | raw_spin_unlock(&busiest_rq->lock); |
7067 | ||
7068 | if (p) | |
7069 | attach_one_task(target_rq, p); | |
7070 | ||
7071 | local_irq_enable(); | |
7072 | ||
969c7921 | 7073 | return 0; |
1e3c88bd PZ |
7074 | } |
7075 | ||
d987fc7f MG |
7076 | static inline int on_null_domain(struct rq *rq) |
7077 | { | |
7078 | return unlikely(!rcu_dereference_sched(rq->sd)); | |
7079 | } | |
7080 | ||
3451d024 | 7081 | #ifdef CONFIG_NO_HZ_COMMON |
83cd4fe2 VP |
7082 | /* |
7083 | * idle load balancing details | |
83cd4fe2 VP |
7084 | * - When one of the busy CPUs notice that there may be an idle rebalancing |
7085 | * needed, they will kick the idle load balancer, which then does idle | |
7086 | * load balancing for all the idle CPUs. | |
7087 | */ | |
1e3c88bd | 7088 | static struct { |
83cd4fe2 | 7089 | cpumask_var_t idle_cpus_mask; |
0b005cf5 | 7090 | atomic_t nr_cpus; |
83cd4fe2 VP |
7091 | unsigned long next_balance; /* in jiffy units */ |
7092 | } nohz ____cacheline_aligned; | |
1e3c88bd | 7093 | |
3dd0337d | 7094 | static inline int find_new_ilb(void) |
1e3c88bd | 7095 | { |
0b005cf5 | 7096 | int ilb = cpumask_first(nohz.idle_cpus_mask); |
1e3c88bd | 7097 | |
786d6dc7 SS |
7098 | if (ilb < nr_cpu_ids && idle_cpu(ilb)) |
7099 | return ilb; | |
7100 | ||
7101 | return nr_cpu_ids; | |
1e3c88bd | 7102 | } |
1e3c88bd | 7103 | |
83cd4fe2 VP |
7104 | /* |
7105 | * Kick a CPU to do the nohz balancing, if it is time for it. We pick the | |
7106 | * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle | |
7107 | * CPU (if there is one). | |
7108 | */ | |
0aeeeeba | 7109 | static void nohz_balancer_kick(void) |
83cd4fe2 VP |
7110 | { |
7111 | int ilb_cpu; | |
7112 | ||
7113 | nohz.next_balance++; | |
7114 | ||
3dd0337d | 7115 | ilb_cpu = find_new_ilb(); |
83cd4fe2 | 7116 | |
0b005cf5 SS |
7117 | if (ilb_cpu >= nr_cpu_ids) |
7118 | return; | |
83cd4fe2 | 7119 | |
cd490c5b | 7120 | if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu))) |
1c792db7 SS |
7121 | return; |
7122 | /* | |
7123 | * Use smp_send_reschedule() instead of resched_cpu(). | |
7124 | * This way we generate a sched IPI on the target cpu which | |
7125 | * is idle. And the softirq performing nohz idle load balance | |
7126 | * will be run before returning from the IPI. | |
7127 | */ | |
7128 | smp_send_reschedule(ilb_cpu); | |
83cd4fe2 VP |
7129 | return; |
7130 | } | |
7131 | ||
c1cc017c | 7132 | static inline void nohz_balance_exit_idle(int cpu) |
71325960 SS |
7133 | { |
7134 | if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) { | |
d987fc7f MG |
7135 | /* |
7136 | * Completely isolated CPUs don't ever set, so we must test. | |
7137 | */ | |
7138 | if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) { | |
7139 | cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); | |
7140 | atomic_dec(&nohz.nr_cpus); | |
7141 | } | |
71325960 SS |
7142 | clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); |
7143 | } | |
7144 | } | |
7145 | ||
69e1e811 SS |
7146 | static inline void set_cpu_sd_state_busy(void) |
7147 | { | |
7148 | struct sched_domain *sd; | |
37dc6b50 | 7149 | int cpu = smp_processor_id(); |
69e1e811 | 7150 | |
69e1e811 | 7151 | rcu_read_lock(); |
37dc6b50 | 7152 | sd = rcu_dereference(per_cpu(sd_busy, cpu)); |
25f55d9d VG |
7153 | |
7154 | if (!sd || !sd->nohz_idle) | |
7155 | goto unlock; | |
7156 | sd->nohz_idle = 0; | |
7157 | ||
63b2ca30 | 7158 | atomic_inc(&sd->groups->sgc->nr_busy_cpus); |
25f55d9d | 7159 | unlock: |
69e1e811 SS |
7160 | rcu_read_unlock(); |
7161 | } | |
7162 | ||
7163 | void set_cpu_sd_state_idle(void) | |
7164 | { | |
7165 | struct sched_domain *sd; | |
37dc6b50 | 7166 | int cpu = smp_processor_id(); |
69e1e811 | 7167 | |
69e1e811 | 7168 | rcu_read_lock(); |
37dc6b50 | 7169 | sd = rcu_dereference(per_cpu(sd_busy, cpu)); |
25f55d9d VG |
7170 | |
7171 | if (!sd || sd->nohz_idle) | |
7172 | goto unlock; | |
7173 | sd->nohz_idle = 1; | |
7174 | ||
63b2ca30 | 7175 | atomic_dec(&sd->groups->sgc->nr_busy_cpus); |
25f55d9d | 7176 | unlock: |
69e1e811 SS |
7177 | rcu_read_unlock(); |
7178 | } | |
7179 | ||
1e3c88bd | 7180 | /* |
c1cc017c | 7181 | * This routine will record that the cpu is going idle with tick stopped. |
0b005cf5 | 7182 | * This info will be used in performing idle load balancing in the future. |
1e3c88bd | 7183 | */ |
c1cc017c | 7184 | void nohz_balance_enter_idle(int cpu) |
1e3c88bd | 7185 | { |
71325960 SS |
7186 | /* |
7187 | * If this cpu is going down, then nothing needs to be done. | |
7188 | */ | |
7189 | if (!cpu_active(cpu)) | |
7190 | return; | |
7191 | ||
c1cc017c AS |
7192 | if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) |
7193 | return; | |
1e3c88bd | 7194 | |
d987fc7f MG |
7195 | /* |
7196 | * If we're a completely isolated CPU, we don't play. | |
7197 | */ | |
7198 | if (on_null_domain(cpu_rq(cpu))) | |
7199 | return; | |
7200 | ||
c1cc017c AS |
7201 | cpumask_set_cpu(cpu, nohz.idle_cpus_mask); |
7202 | atomic_inc(&nohz.nr_cpus); | |
7203 | set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); | |
1e3c88bd | 7204 | } |
71325960 | 7205 | |
0db0628d | 7206 | static int sched_ilb_notifier(struct notifier_block *nfb, |
71325960 SS |
7207 | unsigned long action, void *hcpu) |
7208 | { | |
7209 | switch (action & ~CPU_TASKS_FROZEN) { | |
7210 | case CPU_DYING: | |
c1cc017c | 7211 | nohz_balance_exit_idle(smp_processor_id()); |
71325960 SS |
7212 | return NOTIFY_OK; |
7213 | default: | |
7214 | return NOTIFY_DONE; | |
7215 | } | |
7216 | } | |
1e3c88bd PZ |
7217 | #endif |
7218 | ||
7219 | static DEFINE_SPINLOCK(balancing); | |
7220 | ||
49c022e6 PZ |
7221 | /* |
7222 | * Scale the max load_balance interval with the number of CPUs in the system. | |
7223 | * This trades load-balance latency on larger machines for less cross talk. | |
7224 | */ | |
029632fb | 7225 | void update_max_interval(void) |
49c022e6 PZ |
7226 | { |
7227 | max_load_balance_interval = HZ*num_online_cpus()/10; | |
7228 | } | |
7229 | ||
1e3c88bd PZ |
7230 | /* |
7231 | * It checks each scheduling domain to see if it is due to be balanced, | |
7232 | * and initiates a balancing operation if so. | |
7233 | * | |
b9b0853a | 7234 | * Balancing parameters are set up in init_sched_domains. |
1e3c88bd | 7235 | */ |
f7ed0a89 | 7236 | static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) |
1e3c88bd | 7237 | { |
23f0d209 | 7238 | int continue_balancing = 1; |
f7ed0a89 | 7239 | int cpu = rq->cpu; |
1e3c88bd | 7240 | unsigned long interval; |
04f733b4 | 7241 | struct sched_domain *sd; |
1e3c88bd PZ |
7242 | /* Earliest time when we have to do rebalance again */ |
7243 | unsigned long next_balance = jiffies + 60*HZ; | |
7244 | int update_next_balance = 0; | |
f48627e6 JL |
7245 | int need_serialize, need_decay = 0; |
7246 | u64 max_cost = 0; | |
1e3c88bd | 7247 | |
48a16753 | 7248 | update_blocked_averages(cpu); |
2069dd75 | 7249 | |
dce840a0 | 7250 | rcu_read_lock(); |
1e3c88bd | 7251 | for_each_domain(cpu, sd) { |
f48627e6 JL |
7252 | /* |
7253 | * Decay the newidle max times here because this is a regular | |
7254 | * visit to all the domains. Decay ~1% per second. | |
7255 | */ | |
7256 | if (time_after(jiffies, sd->next_decay_max_lb_cost)) { | |
7257 | sd->max_newidle_lb_cost = | |
7258 | (sd->max_newidle_lb_cost * 253) / 256; | |
7259 | sd->next_decay_max_lb_cost = jiffies + HZ; | |
7260 | need_decay = 1; | |
7261 | } | |
7262 | max_cost += sd->max_newidle_lb_cost; | |
7263 | ||
1e3c88bd PZ |
7264 | if (!(sd->flags & SD_LOAD_BALANCE)) |
7265 | continue; | |
7266 | ||
f48627e6 JL |
7267 | /* |
7268 | * Stop the load balance at this level. There is another | |
7269 | * CPU in our sched group which is doing load balancing more | |
7270 | * actively. | |
7271 | */ | |
7272 | if (!continue_balancing) { | |
7273 | if (need_decay) | |
7274 | continue; | |
7275 | break; | |
7276 | } | |
7277 | ||
52a08ef1 | 7278 | interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
1e3c88bd PZ |
7279 | |
7280 | need_serialize = sd->flags & SD_SERIALIZE; | |
1e3c88bd PZ |
7281 | if (need_serialize) { |
7282 | if (!spin_trylock(&balancing)) | |
7283 | goto out; | |
7284 | } | |
7285 | ||
7286 | if (time_after_eq(jiffies, sd->last_balance + interval)) { | |
23f0d209 | 7287 | if (load_balance(cpu, rq, sd, idle, &continue_balancing)) { |
1e3c88bd | 7288 | /* |
6263322c | 7289 | * The LBF_DST_PINNED logic could have changed |
de5eb2dd JK |
7290 | * env->dst_cpu, so we can't know our idle |
7291 | * state even if we migrated tasks. Update it. | |
1e3c88bd | 7292 | */ |
de5eb2dd | 7293 | idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE; |
1e3c88bd PZ |
7294 | } |
7295 | sd->last_balance = jiffies; | |
52a08ef1 | 7296 | interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
1e3c88bd PZ |
7297 | } |
7298 | if (need_serialize) | |
7299 | spin_unlock(&balancing); | |
7300 | out: | |
7301 | if (time_after(next_balance, sd->last_balance + interval)) { | |
7302 | next_balance = sd->last_balance + interval; | |
7303 | update_next_balance = 1; | |
7304 | } | |
f48627e6 JL |
7305 | } |
7306 | if (need_decay) { | |
1e3c88bd | 7307 | /* |
f48627e6 JL |
7308 | * Ensure the rq-wide value also decays but keep it at a |
7309 | * reasonable floor to avoid funnies with rq->avg_idle. | |
1e3c88bd | 7310 | */ |
f48627e6 JL |
7311 | rq->max_idle_balance_cost = |
7312 | max((u64)sysctl_sched_migration_cost, max_cost); | |
1e3c88bd | 7313 | } |
dce840a0 | 7314 | rcu_read_unlock(); |
1e3c88bd PZ |
7315 | |
7316 | /* | |
7317 | * next_balance will be updated only when there is a need. | |
7318 | * When the cpu is attached to null domain for ex, it will not be | |
7319 | * updated. | |
7320 | */ | |
7321 | if (likely(update_next_balance)) | |
7322 | rq->next_balance = next_balance; | |
7323 | } | |
7324 | ||
3451d024 | 7325 | #ifdef CONFIG_NO_HZ_COMMON |
1e3c88bd | 7326 | /* |
3451d024 | 7327 | * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the |
1e3c88bd PZ |
7328 | * rebalancing for all the cpus for whom scheduler ticks are stopped. |
7329 | */ | |
208cb16b | 7330 | static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) |
83cd4fe2 | 7331 | { |
208cb16b | 7332 | int this_cpu = this_rq->cpu; |
83cd4fe2 VP |
7333 | struct rq *rq; |
7334 | int balance_cpu; | |
7335 | ||
1c792db7 SS |
7336 | if (idle != CPU_IDLE || |
7337 | !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu))) | |
7338 | goto end; | |
83cd4fe2 VP |
7339 | |
7340 | for_each_cpu(balance_cpu, nohz.idle_cpus_mask) { | |
8a6d42d1 | 7341 | if (balance_cpu == this_cpu || !idle_cpu(balance_cpu)) |
83cd4fe2 VP |
7342 | continue; |
7343 | ||
7344 | /* | |
7345 | * If this cpu gets work to do, stop the load balancing | |
7346 | * work being done for other cpus. Next load | |
7347 | * balancing owner will pick it up. | |
7348 | */ | |
1c792db7 | 7349 | if (need_resched()) |
83cd4fe2 | 7350 | break; |
83cd4fe2 | 7351 | |
5ed4f1d9 VG |
7352 | rq = cpu_rq(balance_cpu); |
7353 | ||
ed61bbc6 TC |
7354 | /* |
7355 | * If time for next balance is due, | |
7356 | * do the balance. | |
7357 | */ | |
7358 | if (time_after_eq(jiffies, rq->next_balance)) { | |
7359 | raw_spin_lock_irq(&rq->lock); | |
7360 | update_rq_clock(rq); | |
7361 | update_idle_cpu_load(rq); | |
7362 | raw_spin_unlock_irq(&rq->lock); | |
7363 | rebalance_domains(rq, CPU_IDLE); | |
7364 | } | |
83cd4fe2 | 7365 | |
83cd4fe2 VP |
7366 | if (time_after(this_rq->next_balance, rq->next_balance)) |
7367 | this_rq->next_balance = rq->next_balance; | |
7368 | } | |
7369 | nohz.next_balance = this_rq->next_balance; | |
1c792db7 SS |
7370 | end: |
7371 | clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)); | |
83cd4fe2 VP |
7372 | } |
7373 | ||
7374 | /* | |
0b005cf5 SS |
7375 | * Current heuristic for kicking the idle load balancer in the presence |
7376 | * of an idle cpu is the system. | |
7377 | * - This rq has more than one task. | |
7378 | * - At any scheduler domain level, this cpu's scheduler group has multiple | |
63b2ca30 | 7379 | * busy cpu's exceeding the group's capacity. |
0b005cf5 SS |
7380 | * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler |
7381 | * domain span are idle. | |
83cd4fe2 | 7382 | */ |
4a725627 | 7383 | static inline int nohz_kick_needed(struct rq *rq) |
83cd4fe2 VP |
7384 | { |
7385 | unsigned long now = jiffies; | |
0b005cf5 | 7386 | struct sched_domain *sd; |
63b2ca30 | 7387 | struct sched_group_capacity *sgc; |
4a725627 | 7388 | int nr_busy, cpu = rq->cpu; |
83cd4fe2 | 7389 | |
4a725627 | 7390 | if (unlikely(rq->idle_balance)) |
83cd4fe2 VP |
7391 | return 0; |
7392 | ||
1c792db7 SS |
7393 | /* |
7394 | * We may be recently in ticked or tickless idle mode. At the first | |
7395 | * busy tick after returning from idle, we will update the busy stats. | |
7396 | */ | |
69e1e811 | 7397 | set_cpu_sd_state_busy(); |
c1cc017c | 7398 | nohz_balance_exit_idle(cpu); |
0b005cf5 SS |
7399 | |
7400 | /* | |
7401 | * None are in tickless mode and hence no need for NOHZ idle load | |
7402 | * balancing. | |
7403 | */ | |
7404 | if (likely(!atomic_read(&nohz.nr_cpus))) | |
7405 | return 0; | |
1c792db7 SS |
7406 | |
7407 | if (time_before(now, nohz.next_balance)) | |
83cd4fe2 VP |
7408 | return 0; |
7409 | ||
0b005cf5 SS |
7410 | if (rq->nr_running >= 2) |
7411 | goto need_kick; | |
83cd4fe2 | 7412 | |
067491b7 | 7413 | rcu_read_lock(); |
37dc6b50 | 7414 | sd = rcu_dereference(per_cpu(sd_busy, cpu)); |
83cd4fe2 | 7415 | |
37dc6b50 | 7416 | if (sd) { |
63b2ca30 NP |
7417 | sgc = sd->groups->sgc; |
7418 | nr_busy = atomic_read(&sgc->nr_busy_cpus); | |
0b005cf5 | 7419 | |
37dc6b50 | 7420 | if (nr_busy > 1) |
067491b7 | 7421 | goto need_kick_unlock; |
83cd4fe2 | 7422 | } |
37dc6b50 PM |
7423 | |
7424 | sd = rcu_dereference(per_cpu(sd_asym, cpu)); | |
7425 | ||
7426 | if (sd && (cpumask_first_and(nohz.idle_cpus_mask, | |
7427 | sched_domain_span(sd)) < cpu)) | |
7428 | goto need_kick_unlock; | |
7429 | ||
067491b7 | 7430 | rcu_read_unlock(); |
83cd4fe2 | 7431 | return 0; |
067491b7 PZ |
7432 | |
7433 | need_kick_unlock: | |
7434 | rcu_read_unlock(); | |
0b005cf5 SS |
7435 | need_kick: |
7436 | return 1; | |
83cd4fe2 VP |
7437 | } |
7438 | #else | |
208cb16b | 7439 | static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { } |
83cd4fe2 VP |
7440 | #endif |
7441 | ||
7442 | /* | |
7443 | * run_rebalance_domains is triggered when needed from the scheduler tick. | |
7444 | * Also triggered for nohz idle balancing (with nohz_balancing_kick set). | |
7445 | */ | |
1e3c88bd PZ |
7446 | static void run_rebalance_domains(struct softirq_action *h) |
7447 | { | |
208cb16b | 7448 | struct rq *this_rq = this_rq(); |
6eb57e0d | 7449 | enum cpu_idle_type idle = this_rq->idle_balance ? |
1e3c88bd PZ |
7450 | CPU_IDLE : CPU_NOT_IDLE; |
7451 | ||
f7ed0a89 | 7452 | rebalance_domains(this_rq, idle); |
1e3c88bd | 7453 | |
1e3c88bd | 7454 | /* |
83cd4fe2 | 7455 | * If this cpu has a pending nohz_balance_kick, then do the |
1e3c88bd PZ |
7456 | * balancing on behalf of the other idle cpus whose ticks are |
7457 | * stopped. | |
7458 | */ | |
208cb16b | 7459 | nohz_idle_balance(this_rq, idle); |
1e3c88bd PZ |
7460 | } |
7461 | ||
1e3c88bd PZ |
7462 | /* |
7463 | * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing. | |
1e3c88bd | 7464 | */ |
7caff66f | 7465 | void trigger_load_balance(struct rq *rq) |
1e3c88bd | 7466 | { |
1e3c88bd | 7467 | /* Don't need to rebalance while attached to NULL domain */ |
c726099e DL |
7468 | if (unlikely(on_null_domain(rq))) |
7469 | return; | |
7470 | ||
7471 | if (time_after_eq(jiffies, rq->next_balance)) | |
1e3c88bd | 7472 | raise_softirq(SCHED_SOFTIRQ); |
3451d024 | 7473 | #ifdef CONFIG_NO_HZ_COMMON |
c726099e | 7474 | if (nohz_kick_needed(rq)) |
0aeeeeba | 7475 | nohz_balancer_kick(); |
83cd4fe2 | 7476 | #endif |
1e3c88bd PZ |
7477 | } |
7478 | ||
0bcdcf28 CE |
7479 | static void rq_online_fair(struct rq *rq) |
7480 | { | |
7481 | update_sysctl(); | |
0e59bdae KT |
7482 | |
7483 | update_runtime_enabled(rq); | |
0bcdcf28 CE |
7484 | } |
7485 | ||
7486 | static void rq_offline_fair(struct rq *rq) | |
7487 | { | |
7488 | update_sysctl(); | |
a4c96ae3 PB |
7489 | |
7490 | /* Ensure any throttled groups are reachable by pick_next_task */ | |
7491 | unthrottle_offline_cfs_rqs(rq); | |
0bcdcf28 CE |
7492 | } |
7493 | ||
55e12e5e | 7494 | #endif /* CONFIG_SMP */ |
e1d1484f | 7495 | |
bf0f6f24 IM |
7496 | /* |
7497 | * scheduler tick hitting a task of our scheduling class: | |
7498 | */ | |
8f4d37ec | 7499 | static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) |
bf0f6f24 IM |
7500 | { |
7501 | struct cfs_rq *cfs_rq; | |
7502 | struct sched_entity *se = &curr->se; | |
7503 | ||
7504 | for_each_sched_entity(se) { | |
7505 | cfs_rq = cfs_rq_of(se); | |
8f4d37ec | 7506 | entity_tick(cfs_rq, se, queued); |
bf0f6f24 | 7507 | } |
18bf2805 | 7508 | |
10e84b97 | 7509 | if (numabalancing_enabled) |
cbee9f88 | 7510 | task_tick_numa(rq, curr); |
3d59eebc | 7511 | |
18bf2805 | 7512 | update_rq_runnable_avg(rq, 1); |
bf0f6f24 IM |
7513 | } |
7514 | ||
7515 | /* | |
cd29fe6f PZ |
7516 | * called on fork with the child task as argument from the parent's context |
7517 | * - child not yet on the tasklist | |
7518 | * - preemption disabled | |
bf0f6f24 | 7519 | */ |
cd29fe6f | 7520 | static void task_fork_fair(struct task_struct *p) |
bf0f6f24 | 7521 | { |
4fc420c9 DN |
7522 | struct cfs_rq *cfs_rq; |
7523 | struct sched_entity *se = &p->se, *curr; | |
00bf7bfc | 7524 | int this_cpu = smp_processor_id(); |
cd29fe6f PZ |
7525 | struct rq *rq = this_rq(); |
7526 | unsigned long flags; | |
7527 | ||
05fa785c | 7528 | raw_spin_lock_irqsave(&rq->lock, flags); |
bf0f6f24 | 7529 | |
861d034e PZ |
7530 | update_rq_clock(rq); |
7531 | ||
4fc420c9 DN |
7532 | cfs_rq = task_cfs_rq(current); |
7533 | curr = cfs_rq->curr; | |
7534 | ||
6c9a27f5 DN |
7535 | /* |
7536 | * Not only the cpu but also the task_group of the parent might have | |
7537 | * been changed after parent->se.parent,cfs_rq were copied to | |
7538 | * child->se.parent,cfs_rq. So call __set_task_cpu() to make those | |
7539 | * of child point to valid ones. | |
7540 | */ | |
7541 | rcu_read_lock(); | |
7542 | __set_task_cpu(p, this_cpu); | |
7543 | rcu_read_unlock(); | |
bf0f6f24 | 7544 | |
7109c442 | 7545 | update_curr(cfs_rq); |
cd29fe6f | 7546 | |
b5d9d734 MG |
7547 | if (curr) |
7548 | se->vruntime = curr->vruntime; | |
aeb73b04 | 7549 | place_entity(cfs_rq, se, 1); |
4d78e7b6 | 7550 | |
cd29fe6f | 7551 | if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { |
87fefa38 | 7552 | /* |
edcb60a3 IM |
7553 | * Upon rescheduling, sched_class::put_prev_task() will place |
7554 | * 'current' within the tree based on its new key value. | |
7555 | */ | |
4d78e7b6 | 7556 | swap(curr->vruntime, se->vruntime); |
8875125e | 7557 | resched_curr(rq); |
4d78e7b6 | 7558 | } |
bf0f6f24 | 7559 | |
88ec22d3 PZ |
7560 | se->vruntime -= cfs_rq->min_vruntime; |
7561 | ||
05fa785c | 7562 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
bf0f6f24 IM |
7563 | } |
7564 | ||
cb469845 SR |
7565 | /* |
7566 | * Priority of the task has changed. Check to see if we preempt | |
7567 | * the current task. | |
7568 | */ | |
da7a735e PZ |
7569 | static void |
7570 | prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio) | |
cb469845 | 7571 | { |
da0c1e65 | 7572 | if (!task_on_rq_queued(p)) |
da7a735e PZ |
7573 | return; |
7574 | ||
cb469845 SR |
7575 | /* |
7576 | * Reschedule if we are currently running on this runqueue and | |
7577 | * our priority decreased, or if we are not currently running on | |
7578 | * this runqueue and our priority is higher than the current's | |
7579 | */ | |
da7a735e | 7580 | if (rq->curr == p) { |
cb469845 | 7581 | if (p->prio > oldprio) |
8875125e | 7582 | resched_curr(rq); |
cb469845 | 7583 | } else |
15afe09b | 7584 | check_preempt_curr(rq, p, 0); |
cb469845 SR |
7585 | } |
7586 | ||
da7a735e PZ |
7587 | static void switched_from_fair(struct rq *rq, struct task_struct *p) |
7588 | { | |
7589 | struct sched_entity *se = &p->se; | |
7590 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
7591 | ||
7592 | /* | |
791c9e02 | 7593 | * Ensure the task's vruntime is normalized, so that when it's |
da7a735e PZ |
7594 | * switched back to the fair class the enqueue_entity(.flags=0) will |
7595 | * do the right thing. | |
7596 | * | |
da0c1e65 KT |
7597 | * If it's queued, then the dequeue_entity(.flags=0) will already |
7598 | * have normalized the vruntime, if it's !queued, then only when | |
da7a735e PZ |
7599 | * the task is sleeping will it still have non-normalized vruntime. |
7600 | */ | |
da0c1e65 | 7601 | if (!task_on_rq_queued(p) && p->state != TASK_RUNNING) { |
da7a735e PZ |
7602 | /* |
7603 | * Fix up our vruntime so that the current sleep doesn't | |
7604 | * cause 'unlimited' sleep bonus. | |
7605 | */ | |
7606 | place_entity(cfs_rq, se, 0); | |
7607 | se->vruntime -= cfs_rq->min_vruntime; | |
7608 | } | |
9ee474f5 | 7609 | |
141965c7 | 7610 | #ifdef CONFIG_SMP |
9ee474f5 PT |
7611 | /* |
7612 | * Remove our load from contribution when we leave sched_fair | |
7613 | * and ensure we don't carry in an old decay_count if we | |
7614 | * switch back. | |
7615 | */ | |
87e3c8ae KT |
7616 | if (se->avg.decay_count) { |
7617 | __synchronize_entity_decay(se); | |
7618 | subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib); | |
9ee474f5 PT |
7619 | } |
7620 | #endif | |
da7a735e PZ |
7621 | } |
7622 | ||
cb469845 SR |
7623 | /* |
7624 | * We switched to the sched_fair class. | |
7625 | */ | |
da7a735e | 7626 | static void switched_to_fair(struct rq *rq, struct task_struct *p) |
cb469845 | 7627 | { |
eb7a59b2 | 7628 | #ifdef CONFIG_FAIR_GROUP_SCHED |
f36c019c | 7629 | struct sched_entity *se = &p->se; |
eb7a59b2 M |
7630 | /* |
7631 | * Since the real-depth could have been changed (only FAIR | |
7632 | * class maintain depth value), reset depth properly. | |
7633 | */ | |
7634 | se->depth = se->parent ? se->parent->depth + 1 : 0; | |
7635 | #endif | |
da0c1e65 | 7636 | if (!task_on_rq_queued(p)) |
da7a735e PZ |
7637 | return; |
7638 | ||
cb469845 SR |
7639 | /* |
7640 | * We were most likely switched from sched_rt, so | |
7641 | * kick off the schedule if running, otherwise just see | |
7642 | * if we can still preempt the current task. | |
7643 | */ | |
da7a735e | 7644 | if (rq->curr == p) |
8875125e | 7645 | resched_curr(rq); |
cb469845 | 7646 | else |
15afe09b | 7647 | check_preempt_curr(rq, p, 0); |
cb469845 SR |
7648 | } |
7649 | ||
83b699ed SV |
7650 | /* Account for a task changing its policy or group. |
7651 | * | |
7652 | * This routine is mostly called to set cfs_rq->curr field when a task | |
7653 | * migrates between groups/classes. | |
7654 | */ | |
7655 | static void set_curr_task_fair(struct rq *rq) | |
7656 | { | |
7657 | struct sched_entity *se = &rq->curr->se; | |
7658 | ||
ec12cb7f PT |
7659 | for_each_sched_entity(se) { |
7660 | struct cfs_rq *cfs_rq = cfs_rq_of(se); | |
7661 | ||
7662 | set_next_entity(cfs_rq, se); | |
7663 | /* ensure bandwidth has been allocated on our new cfs_rq */ | |
7664 | account_cfs_rq_runtime(cfs_rq, 0); | |
7665 | } | |
83b699ed SV |
7666 | } |
7667 | ||
029632fb PZ |
7668 | void init_cfs_rq(struct cfs_rq *cfs_rq) |
7669 | { | |
7670 | cfs_rq->tasks_timeline = RB_ROOT; | |
029632fb PZ |
7671 | cfs_rq->min_vruntime = (u64)(-(1LL << 20)); |
7672 | #ifndef CONFIG_64BIT | |
7673 | cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; | |
7674 | #endif | |
141965c7 | 7675 | #ifdef CONFIG_SMP |
9ee474f5 | 7676 | atomic64_set(&cfs_rq->decay_counter, 1); |
2509940f | 7677 | atomic_long_set(&cfs_rq->removed_load, 0); |
9ee474f5 | 7678 | #endif |
029632fb PZ |
7679 | } |
7680 | ||
810b3817 | 7681 | #ifdef CONFIG_FAIR_GROUP_SCHED |
da0c1e65 | 7682 | static void task_move_group_fair(struct task_struct *p, int queued) |
810b3817 | 7683 | { |
fed14d45 | 7684 | struct sched_entity *se = &p->se; |
aff3e498 | 7685 | struct cfs_rq *cfs_rq; |
fed14d45 | 7686 | |
b2b5ce02 PZ |
7687 | /* |
7688 | * If the task was not on the rq at the time of this cgroup movement | |
7689 | * it must have been asleep, sleeping tasks keep their ->vruntime | |
7690 | * absolute on their old rq until wakeup (needed for the fair sleeper | |
7691 | * bonus in place_entity()). | |
7692 | * | |
7693 | * If it was on the rq, we've just 'preempted' it, which does convert | |
7694 | * ->vruntime to a relative base. | |
7695 | * | |
7696 | * Make sure both cases convert their relative position when migrating | |
7697 | * to another cgroup's rq. This does somewhat interfere with the | |
7698 | * fair sleeper stuff for the first placement, but who cares. | |
7699 | */ | |
7ceff013 | 7700 | /* |
da0c1e65 | 7701 | * When !queued, vruntime of the task has usually NOT been normalized. |
7ceff013 DN |
7702 | * But there are some cases where it has already been normalized: |
7703 | * | |
7704 | * - Moving a forked child which is waiting for being woken up by | |
7705 | * wake_up_new_task(). | |
62af3783 DN |
7706 | * - Moving a task which has been woken up by try_to_wake_up() and |
7707 | * waiting for actually being woken up by sched_ttwu_pending(). | |
7ceff013 DN |
7708 | * |
7709 | * To prevent boost or penalty in the new cfs_rq caused by delta | |
7710 | * min_vruntime between the two cfs_rqs, we skip vruntime adjustment. | |
7711 | */ | |
da0c1e65 KT |
7712 | if (!queued && (!se->sum_exec_runtime || p->state == TASK_WAKING)) |
7713 | queued = 1; | |
7ceff013 | 7714 | |
da0c1e65 | 7715 | if (!queued) |
fed14d45 | 7716 | se->vruntime -= cfs_rq_of(se)->min_vruntime; |
b2b5ce02 | 7717 | set_task_rq(p, task_cpu(p)); |
fed14d45 | 7718 | se->depth = se->parent ? se->parent->depth + 1 : 0; |
da0c1e65 | 7719 | if (!queued) { |
fed14d45 PZ |
7720 | cfs_rq = cfs_rq_of(se); |
7721 | se->vruntime += cfs_rq->min_vruntime; | |
aff3e498 PT |
7722 | #ifdef CONFIG_SMP |
7723 | /* | |
7724 | * migrate_task_rq_fair() will have removed our previous | |
7725 | * contribution, but we must synchronize for ongoing future | |
7726 | * decay. | |
7727 | */ | |
fed14d45 PZ |
7728 | se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter); |
7729 | cfs_rq->blocked_load_avg += se->avg.load_avg_contrib; | |
aff3e498 PT |
7730 | #endif |
7731 | } | |
810b3817 | 7732 | } |
029632fb PZ |
7733 | |
7734 | void free_fair_sched_group(struct task_group *tg) | |
7735 | { | |
7736 | int i; | |
7737 | ||
7738 | destroy_cfs_bandwidth(tg_cfs_bandwidth(tg)); | |
7739 | ||
7740 | for_each_possible_cpu(i) { | |
7741 | if (tg->cfs_rq) | |
7742 | kfree(tg->cfs_rq[i]); | |
7743 | if (tg->se) | |
7744 | kfree(tg->se[i]); | |
7745 | } | |
7746 | ||
7747 | kfree(tg->cfs_rq); | |
7748 | kfree(tg->se); | |
7749 | } | |
7750 | ||
7751 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) | |
7752 | { | |
7753 | struct cfs_rq *cfs_rq; | |
7754 | struct sched_entity *se; | |
7755 | int i; | |
7756 | ||
7757 | tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL); | |
7758 | if (!tg->cfs_rq) | |
7759 | goto err; | |
7760 | tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL); | |
7761 | if (!tg->se) | |
7762 | goto err; | |
7763 | ||
7764 | tg->shares = NICE_0_LOAD; | |
7765 | ||
7766 | init_cfs_bandwidth(tg_cfs_bandwidth(tg)); | |
7767 | ||
7768 | for_each_possible_cpu(i) { | |
7769 | cfs_rq = kzalloc_node(sizeof(struct cfs_rq), | |
7770 | GFP_KERNEL, cpu_to_node(i)); | |
7771 | if (!cfs_rq) | |
7772 | goto err; | |
7773 | ||
7774 | se = kzalloc_node(sizeof(struct sched_entity), | |
7775 | GFP_KERNEL, cpu_to_node(i)); | |
7776 | if (!se) | |
7777 | goto err_free_rq; | |
7778 | ||
7779 | init_cfs_rq(cfs_rq); | |
7780 | init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]); | |
7781 | } | |
7782 | ||
7783 | return 1; | |
7784 | ||
7785 | err_free_rq: | |
7786 | kfree(cfs_rq); | |
7787 | err: | |
7788 | return 0; | |
7789 | } | |
7790 | ||
7791 | void unregister_fair_sched_group(struct task_group *tg, int cpu) | |
7792 | { | |
7793 | struct rq *rq = cpu_rq(cpu); | |
7794 | unsigned long flags; | |
7795 | ||
7796 | /* | |
7797 | * Only empty task groups can be destroyed; so we can speculatively | |
7798 | * check on_list without danger of it being re-added. | |
7799 | */ | |
7800 | if (!tg->cfs_rq[cpu]->on_list) | |
7801 | return; | |
7802 | ||
7803 | raw_spin_lock_irqsave(&rq->lock, flags); | |
7804 | list_del_leaf_cfs_rq(tg->cfs_rq[cpu]); | |
7805 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
7806 | } | |
7807 | ||
7808 | void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, | |
7809 | struct sched_entity *se, int cpu, | |
7810 | struct sched_entity *parent) | |
7811 | { | |
7812 | struct rq *rq = cpu_rq(cpu); | |
7813 | ||
7814 | cfs_rq->tg = tg; | |
7815 | cfs_rq->rq = rq; | |
029632fb PZ |
7816 | init_cfs_rq_runtime(cfs_rq); |
7817 | ||
7818 | tg->cfs_rq[cpu] = cfs_rq; | |
7819 | tg->se[cpu] = se; | |
7820 | ||
7821 | /* se could be NULL for root_task_group */ | |
7822 | if (!se) | |
7823 | return; | |
7824 | ||
fed14d45 | 7825 | if (!parent) { |
029632fb | 7826 | se->cfs_rq = &rq->cfs; |
fed14d45 PZ |
7827 | se->depth = 0; |
7828 | } else { | |
029632fb | 7829 | se->cfs_rq = parent->my_q; |
fed14d45 PZ |
7830 | se->depth = parent->depth + 1; |
7831 | } | |
029632fb PZ |
7832 | |
7833 | se->my_q = cfs_rq; | |
0ac9b1c2 PT |
7834 | /* guarantee group entities always have weight */ |
7835 | update_load_set(&se->load, NICE_0_LOAD); | |
029632fb PZ |
7836 | se->parent = parent; |
7837 | } | |
7838 | ||
7839 | static DEFINE_MUTEX(shares_mutex); | |
7840 | ||
7841 | int sched_group_set_shares(struct task_group *tg, unsigned long shares) | |
7842 | { | |
7843 | int i; | |
7844 | unsigned long flags; | |
7845 | ||
7846 | /* | |
7847 | * We can't change the weight of the root cgroup. | |
7848 | */ | |
7849 | if (!tg->se[0]) | |
7850 | return -EINVAL; | |
7851 | ||
7852 | shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES)); | |
7853 | ||
7854 | mutex_lock(&shares_mutex); | |
7855 | if (tg->shares == shares) | |
7856 | goto done; | |
7857 | ||
7858 | tg->shares = shares; | |
7859 | for_each_possible_cpu(i) { | |
7860 | struct rq *rq = cpu_rq(i); | |
7861 | struct sched_entity *se; | |
7862 | ||
7863 | se = tg->se[i]; | |
7864 | /* Propagate contribution to hierarchy */ | |
7865 | raw_spin_lock_irqsave(&rq->lock, flags); | |
71b1da46 FW |
7866 | |
7867 | /* Possible calls to update_curr() need rq clock */ | |
7868 | update_rq_clock(rq); | |
17bc14b7 | 7869 | for_each_sched_entity(se) |
029632fb PZ |
7870 | update_cfs_shares(group_cfs_rq(se)); |
7871 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
7872 | } | |
7873 | ||
7874 | done: | |
7875 | mutex_unlock(&shares_mutex); | |
7876 | return 0; | |
7877 | } | |
7878 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
7879 | ||
7880 | void free_fair_sched_group(struct task_group *tg) { } | |
7881 | ||
7882 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) | |
7883 | { | |
7884 | return 1; | |
7885 | } | |
7886 | ||
7887 | void unregister_fair_sched_group(struct task_group *tg, int cpu) { } | |
7888 | ||
7889 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
7890 | ||
810b3817 | 7891 | |
6d686f45 | 7892 | static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task) |
0d721cea PW |
7893 | { |
7894 | struct sched_entity *se = &task->se; | |
0d721cea PW |
7895 | unsigned int rr_interval = 0; |
7896 | ||
7897 | /* | |
7898 | * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise | |
7899 | * idle runqueue: | |
7900 | */ | |
0d721cea | 7901 | if (rq->cfs.load.weight) |
a59f4e07 | 7902 | rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); |
0d721cea PW |
7903 | |
7904 | return rr_interval; | |
7905 | } | |
7906 | ||
bf0f6f24 IM |
7907 | /* |
7908 | * All the scheduling class methods: | |
7909 | */ | |
029632fb | 7910 | const struct sched_class fair_sched_class = { |
5522d5d5 | 7911 | .next = &idle_sched_class, |
bf0f6f24 IM |
7912 | .enqueue_task = enqueue_task_fair, |
7913 | .dequeue_task = dequeue_task_fair, | |
7914 | .yield_task = yield_task_fair, | |
d95f4122 | 7915 | .yield_to_task = yield_to_task_fair, |
bf0f6f24 | 7916 | |
2e09bf55 | 7917 | .check_preempt_curr = check_preempt_wakeup, |
bf0f6f24 IM |
7918 | |
7919 | .pick_next_task = pick_next_task_fair, | |
7920 | .put_prev_task = put_prev_task_fair, | |
7921 | ||
681f3e68 | 7922 | #ifdef CONFIG_SMP |
4ce72a2c | 7923 | .select_task_rq = select_task_rq_fair, |
0a74bef8 | 7924 | .migrate_task_rq = migrate_task_rq_fair, |
141965c7 | 7925 | |
0bcdcf28 CE |
7926 | .rq_online = rq_online_fair, |
7927 | .rq_offline = rq_offline_fair, | |
88ec22d3 PZ |
7928 | |
7929 | .task_waking = task_waking_fair, | |
681f3e68 | 7930 | #endif |
bf0f6f24 | 7931 | |
83b699ed | 7932 | .set_curr_task = set_curr_task_fair, |
bf0f6f24 | 7933 | .task_tick = task_tick_fair, |
cd29fe6f | 7934 | .task_fork = task_fork_fair, |
cb469845 SR |
7935 | |
7936 | .prio_changed = prio_changed_fair, | |
da7a735e | 7937 | .switched_from = switched_from_fair, |
cb469845 | 7938 | .switched_to = switched_to_fair, |
810b3817 | 7939 | |
0d721cea PW |
7940 | .get_rr_interval = get_rr_interval_fair, |
7941 | ||
810b3817 | 7942 | #ifdef CONFIG_FAIR_GROUP_SCHED |
b2b5ce02 | 7943 | .task_move_group = task_move_group_fair, |
810b3817 | 7944 | #endif |
bf0f6f24 IM |
7945 | }; |
7946 | ||
7947 | #ifdef CONFIG_SCHED_DEBUG | |
029632fb | 7948 | void print_cfs_stats(struct seq_file *m, int cpu) |
bf0f6f24 | 7949 | { |
bf0f6f24 IM |
7950 | struct cfs_rq *cfs_rq; |
7951 | ||
5973e5b9 | 7952 | rcu_read_lock(); |
c3b64f1e | 7953 | for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) |
5cef9eca | 7954 | print_cfs_rq(m, cpu, cfs_rq); |
5973e5b9 | 7955 | rcu_read_unlock(); |
bf0f6f24 IM |
7956 | } |
7957 | #endif | |
029632fb PZ |
7958 | |
7959 | __init void init_sched_fair_class(void) | |
7960 | { | |
7961 | #ifdef CONFIG_SMP | |
7962 | open_softirq(SCHED_SOFTIRQ, run_rebalance_domains); | |
7963 | ||
3451d024 | 7964 | #ifdef CONFIG_NO_HZ_COMMON |
554cecaf | 7965 | nohz.next_balance = jiffies; |
029632fb | 7966 | zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); |
71325960 | 7967 | cpu_notifier(sched_ilb_notifier, 0); |
029632fb PZ |
7968 | #endif |
7969 | #endif /* SMP */ | |
7970 | ||
7971 | } |