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1da177e4 LT |
1 | /* |
2 | * kernel/sched.c | |
3 | * | |
4 | * Kernel scheduler and related syscalls | |
5 | * | |
6 | * Copyright (C) 1991-2002 Linus Torvalds | |
7 | * | |
8 | * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and | |
9 | * make semaphores SMP safe | |
10 | * 1998-11-19 Implemented schedule_timeout() and related stuff | |
11 | * by Andrea Arcangeli | |
12 | * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar: | |
13 | * hybrid priority-list and round-robin design with | |
14 | * an array-switch method of distributing timeslices | |
15 | * and per-CPU runqueues. Cleanups and useful suggestions | |
16 | * by Davide Libenzi, preemptible kernel bits by Robert Love. | |
17 | * 2003-09-03 Interactivity tuning by Con Kolivas. | |
18 | * 2004-04-02 Scheduler domains code by Nick Piggin | |
19 | */ | |
20 | ||
21 | #include <linux/mm.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/nmi.h> | |
24 | #include <linux/init.h> | |
25 | #include <asm/uaccess.h> | |
26 | #include <linux/highmem.h> | |
27 | #include <linux/smp_lock.h> | |
28 | #include <asm/mmu_context.h> | |
29 | #include <linux/interrupt.h> | |
30 | #include <linux/completion.h> | |
31 | #include <linux/kernel_stat.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/notifier.h> | |
34 | #include <linux/profile.h> | |
35 | #include <linux/suspend.h> | |
36 | #include <linux/blkdev.h> | |
37 | #include <linux/delay.h> | |
38 | #include <linux/smp.h> | |
39 | #include <linux/threads.h> | |
40 | #include <linux/timer.h> | |
41 | #include <linux/rcupdate.h> | |
42 | #include <linux/cpu.h> | |
43 | #include <linux/cpuset.h> | |
44 | #include <linux/percpu.h> | |
45 | #include <linux/kthread.h> | |
46 | #include <linux/seq_file.h> | |
47 | #include <linux/syscalls.h> | |
48 | #include <linux/times.h> | |
49 | #include <linux/acct.h> | |
50 | #include <asm/tlb.h> | |
51 | ||
52 | #include <asm/unistd.h> | |
53 | ||
54 | /* | |
55 | * Convert user-nice values [ -20 ... 0 ... 19 ] | |
56 | * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ], | |
57 | * and back. | |
58 | */ | |
59 | #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20) | |
60 | #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20) | |
61 | #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio) | |
62 | ||
63 | /* | |
64 | * 'User priority' is the nice value converted to something we | |
65 | * can work with better when scaling various scheduler parameters, | |
66 | * it's a [ 0 ... 39 ] range. | |
67 | */ | |
68 | #define USER_PRIO(p) ((p)-MAX_RT_PRIO) | |
69 | #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio) | |
70 | #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO)) | |
71 | ||
72 | /* | |
73 | * Some helpers for converting nanosecond timing to jiffy resolution | |
74 | */ | |
75 | #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ)) | |
76 | #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ)) | |
77 | ||
78 | /* | |
79 | * These are the 'tuning knobs' of the scheduler: | |
80 | * | |
81 | * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger), | |
82 | * default timeslice is 100 msecs, maximum timeslice is 800 msecs. | |
83 | * Timeslices get refilled after they expire. | |
84 | */ | |
85 | #define MIN_TIMESLICE max(5 * HZ / 1000, 1) | |
86 | #define DEF_TIMESLICE (100 * HZ / 1000) | |
87 | #define ON_RUNQUEUE_WEIGHT 30 | |
88 | #define CHILD_PENALTY 95 | |
89 | #define PARENT_PENALTY 100 | |
90 | #define EXIT_WEIGHT 3 | |
91 | #define PRIO_BONUS_RATIO 25 | |
92 | #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100) | |
93 | #define INTERACTIVE_DELTA 2 | |
94 | #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS) | |
95 | #define STARVATION_LIMIT (MAX_SLEEP_AVG) | |
96 | #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG)) | |
97 | ||
98 | /* | |
99 | * If a task is 'interactive' then we reinsert it in the active | |
100 | * array after it has expired its current timeslice. (it will not | |
101 | * continue to run immediately, it will still roundrobin with | |
102 | * other interactive tasks.) | |
103 | * | |
104 | * This part scales the interactivity limit depending on niceness. | |
105 | * | |
106 | * We scale it linearly, offset by the INTERACTIVE_DELTA delta. | |
107 | * Here are a few examples of different nice levels: | |
108 | * | |
109 | * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0] | |
110 | * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0] | |
111 | * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0] | |
112 | * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0] | |
113 | * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0] | |
114 | * | |
115 | * (the X axis represents the possible -5 ... 0 ... +5 dynamic | |
116 | * priority range a task can explore, a value of '1' means the | |
117 | * task is rated interactive.) | |
118 | * | |
119 | * Ie. nice +19 tasks can never get 'interactive' enough to be | |
120 | * reinserted into the active array. And only heavily CPU-hog nice -20 | |
121 | * tasks will be expired. Default nice 0 tasks are somewhere between, | |
122 | * it takes some effort for them to get interactive, but it's not | |
123 | * too hard. | |
124 | */ | |
125 | ||
126 | #define CURRENT_BONUS(p) \ | |
127 | (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \ | |
128 | MAX_SLEEP_AVG) | |
129 | ||
130 | #define GRANULARITY (10 * HZ / 1000 ? : 1) | |
131 | ||
132 | #ifdef CONFIG_SMP | |
133 | #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \ | |
134 | (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \ | |
135 | num_online_cpus()) | |
136 | #else | |
137 | #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \ | |
138 | (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1))) | |
139 | #endif | |
140 | ||
141 | #define SCALE(v1,v1_max,v2_max) \ | |
142 | (v1) * (v2_max) / (v1_max) | |
143 | ||
144 | #define DELTA(p) \ | |
145 | (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA) | |
146 | ||
147 | #define TASK_INTERACTIVE(p) \ | |
148 | ((p)->prio <= (p)->static_prio - DELTA(p)) | |
149 | ||
150 | #define INTERACTIVE_SLEEP(p) \ | |
151 | (JIFFIES_TO_NS(MAX_SLEEP_AVG * \ | |
152 | (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1)) | |
153 | ||
154 | #define TASK_PREEMPTS_CURR(p, rq) \ | |
155 | ((p)->prio < (rq)->curr->prio) | |
156 | ||
157 | /* | |
158 | * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ] | |
159 | * to time slice values: [800ms ... 100ms ... 5ms] | |
160 | * | |
161 | * The higher a thread's priority, the bigger timeslices | |
162 | * it gets during one round of execution. But even the lowest | |
163 | * priority thread gets MIN_TIMESLICE worth of execution time. | |
164 | */ | |
165 | ||
166 | #define SCALE_PRIO(x, prio) \ | |
167 | max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE) | |
168 | ||
169 | static inline unsigned int task_timeslice(task_t *p) | |
170 | { | |
171 | if (p->static_prio < NICE_TO_PRIO(0)) | |
172 | return SCALE_PRIO(DEF_TIMESLICE*4, p->static_prio); | |
173 | else | |
174 | return SCALE_PRIO(DEF_TIMESLICE, p->static_prio); | |
175 | } | |
176 | #define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \ | |
177 | < (long long) (sd)->cache_hot_time) | |
178 | ||
179 | /* | |
180 | * These are the runqueue data structures: | |
181 | */ | |
182 | ||
183 | #define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long)) | |
184 | ||
185 | typedef struct runqueue runqueue_t; | |
186 | ||
187 | struct prio_array { | |
188 | unsigned int nr_active; | |
189 | unsigned long bitmap[BITMAP_SIZE]; | |
190 | struct list_head queue[MAX_PRIO]; | |
191 | }; | |
192 | ||
193 | /* | |
194 | * This is the main, per-CPU runqueue data structure. | |
195 | * | |
196 | * Locking rule: those places that want to lock multiple runqueues | |
197 | * (such as the load balancing or the thread migration code), lock | |
198 | * acquire operations must be ordered by ascending &runqueue. | |
199 | */ | |
200 | struct runqueue { | |
201 | spinlock_t lock; | |
202 | ||
203 | /* | |
204 | * nr_running and cpu_load should be in the same cacheline because | |
205 | * remote CPUs use both these fields when doing load calculation. | |
206 | */ | |
207 | unsigned long nr_running; | |
208 | #ifdef CONFIG_SMP | |
209 | unsigned long cpu_load; | |
210 | #endif | |
211 | unsigned long long nr_switches; | |
212 | ||
213 | /* | |
214 | * This is part of a global counter where only the total sum | |
215 | * over all CPUs matters. A task can increase this counter on | |
216 | * one CPU and if it got migrated afterwards it may decrease | |
217 | * it on another CPU. Always updated under the runqueue lock: | |
218 | */ | |
219 | unsigned long nr_uninterruptible; | |
220 | ||
221 | unsigned long expired_timestamp; | |
222 | unsigned long long timestamp_last_tick; | |
223 | task_t *curr, *idle; | |
224 | struct mm_struct *prev_mm; | |
225 | prio_array_t *active, *expired, arrays[2]; | |
226 | int best_expired_prio; | |
227 | atomic_t nr_iowait; | |
228 | ||
229 | #ifdef CONFIG_SMP | |
230 | struct sched_domain *sd; | |
231 | ||
232 | /* For active balancing */ | |
233 | int active_balance; | |
234 | int push_cpu; | |
235 | ||
236 | task_t *migration_thread; | |
237 | struct list_head migration_queue; | |
238 | #endif | |
239 | ||
240 | #ifdef CONFIG_SCHEDSTATS | |
241 | /* latency stats */ | |
242 | struct sched_info rq_sched_info; | |
243 | ||
244 | /* sys_sched_yield() stats */ | |
245 | unsigned long yld_exp_empty; | |
246 | unsigned long yld_act_empty; | |
247 | unsigned long yld_both_empty; | |
248 | unsigned long yld_cnt; | |
249 | ||
250 | /* schedule() stats */ | |
251 | unsigned long sched_switch; | |
252 | unsigned long sched_cnt; | |
253 | unsigned long sched_goidle; | |
254 | ||
255 | /* try_to_wake_up() stats */ | |
256 | unsigned long ttwu_cnt; | |
257 | unsigned long ttwu_local; | |
258 | #endif | |
259 | }; | |
260 | ||
261 | static DEFINE_PER_CPU(struct runqueue, runqueues); | |
262 | ||
263 | #define for_each_domain(cpu, domain) \ | |
264 | for (domain = cpu_rq(cpu)->sd; domain; domain = domain->parent) | |
265 | ||
266 | #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu))) | |
267 | #define this_rq() (&__get_cpu_var(runqueues)) | |
268 | #define task_rq(p) cpu_rq(task_cpu(p)) | |
269 | #define cpu_curr(cpu) (cpu_rq(cpu)->curr) | |
270 | ||
271 | /* | |
272 | * Default context-switch locking: | |
273 | */ | |
274 | #ifndef prepare_arch_switch | |
275 | # define prepare_arch_switch(rq, next) do { } while (0) | |
276 | # define finish_arch_switch(rq, next) spin_unlock_irq(&(rq)->lock) | |
277 | # define task_running(rq, p) ((rq)->curr == (p)) | |
278 | #endif | |
279 | ||
280 | /* | |
281 | * task_rq_lock - lock the runqueue a given task resides on and disable | |
282 | * interrupts. Note the ordering: we can safely lookup the task_rq without | |
283 | * explicitly disabling preemption. | |
284 | */ | |
285 | static inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags) | |
286 | __acquires(rq->lock) | |
287 | { | |
288 | struct runqueue *rq; | |
289 | ||
290 | repeat_lock_task: | |
291 | local_irq_save(*flags); | |
292 | rq = task_rq(p); | |
293 | spin_lock(&rq->lock); | |
294 | if (unlikely(rq != task_rq(p))) { | |
295 | spin_unlock_irqrestore(&rq->lock, *flags); | |
296 | goto repeat_lock_task; | |
297 | } | |
298 | return rq; | |
299 | } | |
300 | ||
301 | static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags) | |
302 | __releases(rq->lock) | |
303 | { | |
304 | spin_unlock_irqrestore(&rq->lock, *flags); | |
305 | } | |
306 | ||
307 | #ifdef CONFIG_SCHEDSTATS | |
308 | /* | |
309 | * bump this up when changing the output format or the meaning of an existing | |
310 | * format, so that tools can adapt (or abort) | |
311 | */ | |
312 | #define SCHEDSTAT_VERSION 11 | |
313 | ||
314 | static int show_schedstat(struct seq_file *seq, void *v) | |
315 | { | |
316 | int cpu; | |
317 | ||
318 | seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION); | |
319 | seq_printf(seq, "timestamp %lu\n", jiffies); | |
320 | for_each_online_cpu(cpu) { | |
321 | runqueue_t *rq = cpu_rq(cpu); | |
322 | #ifdef CONFIG_SMP | |
323 | struct sched_domain *sd; | |
324 | int dcnt = 0; | |
325 | #endif | |
326 | ||
327 | /* runqueue-specific stats */ | |
328 | seq_printf(seq, | |
329 | "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu", | |
330 | cpu, rq->yld_both_empty, | |
331 | rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt, | |
332 | rq->sched_switch, rq->sched_cnt, rq->sched_goidle, | |
333 | rq->ttwu_cnt, rq->ttwu_local, | |
334 | rq->rq_sched_info.cpu_time, | |
335 | rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt); | |
336 | ||
337 | seq_printf(seq, "\n"); | |
338 | ||
339 | #ifdef CONFIG_SMP | |
340 | /* domain-specific stats */ | |
341 | for_each_domain(cpu, sd) { | |
342 | enum idle_type itype; | |
343 | char mask_str[NR_CPUS]; | |
344 | ||
345 | cpumask_scnprintf(mask_str, NR_CPUS, sd->span); | |
346 | seq_printf(seq, "domain%d %s", dcnt++, mask_str); | |
347 | for (itype = SCHED_IDLE; itype < MAX_IDLE_TYPES; | |
348 | itype++) { | |
349 | seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu", | |
350 | sd->lb_cnt[itype], | |
351 | sd->lb_balanced[itype], | |
352 | sd->lb_failed[itype], | |
353 | sd->lb_imbalance[itype], | |
354 | sd->lb_gained[itype], | |
355 | sd->lb_hot_gained[itype], | |
356 | sd->lb_nobusyq[itype], | |
357 | sd->lb_nobusyg[itype]); | |
358 | } | |
359 | seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu\n", | |
360 | sd->alb_cnt, sd->alb_failed, sd->alb_pushed, | |
361 | sd->sbe_pushed, sd->sbe_attempts, | |
362 | sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance); | |
363 | } | |
364 | #endif | |
365 | } | |
366 | return 0; | |
367 | } | |
368 | ||
369 | static int schedstat_open(struct inode *inode, struct file *file) | |
370 | { | |
371 | unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32); | |
372 | char *buf = kmalloc(size, GFP_KERNEL); | |
373 | struct seq_file *m; | |
374 | int res; | |
375 | ||
376 | if (!buf) | |
377 | return -ENOMEM; | |
378 | res = single_open(file, show_schedstat, NULL); | |
379 | if (!res) { | |
380 | m = file->private_data; | |
381 | m->buf = buf; | |
382 | m->size = size; | |
383 | } else | |
384 | kfree(buf); | |
385 | return res; | |
386 | } | |
387 | ||
388 | struct file_operations proc_schedstat_operations = { | |
389 | .open = schedstat_open, | |
390 | .read = seq_read, | |
391 | .llseek = seq_lseek, | |
392 | .release = single_release, | |
393 | }; | |
394 | ||
395 | # define schedstat_inc(rq, field) do { (rq)->field++; } while (0) | |
396 | # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0) | |
397 | #else /* !CONFIG_SCHEDSTATS */ | |
398 | # define schedstat_inc(rq, field) do { } while (0) | |
399 | # define schedstat_add(rq, field, amt) do { } while (0) | |
400 | #endif | |
401 | ||
402 | /* | |
403 | * rq_lock - lock a given runqueue and disable interrupts. | |
404 | */ | |
405 | static inline runqueue_t *this_rq_lock(void) | |
406 | __acquires(rq->lock) | |
407 | { | |
408 | runqueue_t *rq; | |
409 | ||
410 | local_irq_disable(); | |
411 | rq = this_rq(); | |
412 | spin_lock(&rq->lock); | |
413 | ||
414 | return rq; | |
415 | } | |
416 | ||
417 | #ifdef CONFIG_SCHED_SMT | |
418 | static int cpu_and_siblings_are_idle(int cpu) | |
419 | { | |
420 | int sib; | |
421 | for_each_cpu_mask(sib, cpu_sibling_map[cpu]) { | |
422 | if (idle_cpu(sib)) | |
423 | continue; | |
424 | return 0; | |
425 | } | |
426 | ||
427 | return 1; | |
428 | } | |
429 | #else | |
430 | #define cpu_and_siblings_are_idle(A) idle_cpu(A) | |
431 | #endif | |
432 | ||
433 | #ifdef CONFIG_SCHEDSTATS | |
434 | /* | |
435 | * Called when a process is dequeued from the active array and given | |
436 | * the cpu. We should note that with the exception of interactive | |
437 | * tasks, the expired queue will become the active queue after the active | |
438 | * queue is empty, without explicitly dequeuing and requeuing tasks in the | |
439 | * expired queue. (Interactive tasks may be requeued directly to the | |
440 | * active queue, thus delaying tasks in the expired queue from running; | |
441 | * see scheduler_tick()). | |
442 | * | |
443 | * This function is only called from sched_info_arrive(), rather than | |
444 | * dequeue_task(). Even though a task may be queued and dequeued multiple | |
445 | * times as it is shuffled about, we're really interested in knowing how | |
446 | * long it was from the *first* time it was queued to the time that it | |
447 | * finally hit a cpu. | |
448 | */ | |
449 | static inline void sched_info_dequeued(task_t *t) | |
450 | { | |
451 | t->sched_info.last_queued = 0; | |
452 | } | |
453 | ||
454 | /* | |
455 | * Called when a task finally hits the cpu. We can now calculate how | |
456 | * long it was waiting to run. We also note when it began so that we | |
457 | * can keep stats on how long its timeslice is. | |
458 | */ | |
459 | static inline void sched_info_arrive(task_t *t) | |
460 | { | |
461 | unsigned long now = jiffies, diff = 0; | |
462 | struct runqueue *rq = task_rq(t); | |
463 | ||
464 | if (t->sched_info.last_queued) | |
465 | diff = now - t->sched_info.last_queued; | |
466 | sched_info_dequeued(t); | |
467 | t->sched_info.run_delay += diff; | |
468 | t->sched_info.last_arrival = now; | |
469 | t->sched_info.pcnt++; | |
470 | ||
471 | if (!rq) | |
472 | return; | |
473 | ||
474 | rq->rq_sched_info.run_delay += diff; | |
475 | rq->rq_sched_info.pcnt++; | |
476 | } | |
477 | ||
478 | /* | |
479 | * Called when a process is queued into either the active or expired | |
480 | * array. The time is noted and later used to determine how long we | |
481 | * had to wait for us to reach the cpu. Since the expired queue will | |
482 | * become the active queue after active queue is empty, without dequeuing | |
483 | * and requeuing any tasks, we are interested in queuing to either. It | |
484 | * is unusual but not impossible for tasks to be dequeued and immediately | |
485 | * requeued in the same or another array: this can happen in sched_yield(), | |
486 | * set_user_nice(), and even load_balance() as it moves tasks from runqueue | |
487 | * to runqueue. | |
488 | * | |
489 | * This function is only called from enqueue_task(), but also only updates | |
490 | * the timestamp if it is already not set. It's assumed that | |
491 | * sched_info_dequeued() will clear that stamp when appropriate. | |
492 | */ | |
493 | static inline void sched_info_queued(task_t *t) | |
494 | { | |
495 | if (!t->sched_info.last_queued) | |
496 | t->sched_info.last_queued = jiffies; | |
497 | } | |
498 | ||
499 | /* | |
500 | * Called when a process ceases being the active-running process, either | |
501 | * voluntarily or involuntarily. Now we can calculate how long we ran. | |
502 | */ | |
503 | static inline void sched_info_depart(task_t *t) | |
504 | { | |
505 | struct runqueue *rq = task_rq(t); | |
506 | unsigned long diff = jiffies - t->sched_info.last_arrival; | |
507 | ||
508 | t->sched_info.cpu_time += diff; | |
509 | ||
510 | if (rq) | |
511 | rq->rq_sched_info.cpu_time += diff; | |
512 | } | |
513 | ||
514 | /* | |
515 | * Called when tasks are switched involuntarily due, typically, to expiring | |
516 | * their time slice. (This may also be called when switching to or from | |
517 | * the idle task.) We are only called when prev != next. | |
518 | */ | |
519 | static inline void sched_info_switch(task_t *prev, task_t *next) | |
520 | { | |
521 | struct runqueue *rq = task_rq(prev); | |
522 | ||
523 | /* | |
524 | * prev now departs the cpu. It's not interesting to record | |
525 | * stats about how efficient we were at scheduling the idle | |
526 | * process, however. | |
527 | */ | |
528 | if (prev != rq->idle) | |
529 | sched_info_depart(prev); | |
530 | ||
531 | if (next != rq->idle) | |
532 | sched_info_arrive(next); | |
533 | } | |
534 | #else | |
535 | #define sched_info_queued(t) do { } while (0) | |
536 | #define sched_info_switch(t, next) do { } while (0) | |
537 | #endif /* CONFIG_SCHEDSTATS */ | |
538 | ||
539 | /* | |
540 | * Adding/removing a task to/from a priority array: | |
541 | */ | |
542 | static void dequeue_task(struct task_struct *p, prio_array_t *array) | |
543 | { | |
544 | array->nr_active--; | |
545 | list_del(&p->run_list); | |
546 | if (list_empty(array->queue + p->prio)) | |
547 | __clear_bit(p->prio, array->bitmap); | |
548 | } | |
549 | ||
550 | static void enqueue_task(struct task_struct *p, prio_array_t *array) | |
551 | { | |
552 | sched_info_queued(p); | |
553 | list_add_tail(&p->run_list, array->queue + p->prio); | |
554 | __set_bit(p->prio, array->bitmap); | |
555 | array->nr_active++; | |
556 | p->array = array; | |
557 | } | |
558 | ||
559 | /* | |
560 | * Put task to the end of the run list without the overhead of dequeue | |
561 | * followed by enqueue. | |
562 | */ | |
563 | static void requeue_task(struct task_struct *p, prio_array_t *array) | |
564 | { | |
565 | list_move_tail(&p->run_list, array->queue + p->prio); | |
566 | } | |
567 | ||
568 | static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array) | |
569 | { | |
570 | list_add(&p->run_list, array->queue + p->prio); | |
571 | __set_bit(p->prio, array->bitmap); | |
572 | array->nr_active++; | |
573 | p->array = array; | |
574 | } | |
575 | ||
576 | /* | |
577 | * effective_prio - return the priority that is based on the static | |
578 | * priority but is modified by bonuses/penalties. | |
579 | * | |
580 | * We scale the actual sleep average [0 .... MAX_SLEEP_AVG] | |
581 | * into the -5 ... 0 ... +5 bonus/penalty range. | |
582 | * | |
583 | * We use 25% of the full 0...39 priority range so that: | |
584 | * | |
585 | * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs. | |
586 | * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks. | |
587 | * | |
588 | * Both properties are important to certain workloads. | |
589 | */ | |
590 | static int effective_prio(task_t *p) | |
591 | { | |
592 | int bonus, prio; | |
593 | ||
594 | if (rt_task(p)) | |
595 | return p->prio; | |
596 | ||
597 | bonus = CURRENT_BONUS(p) - MAX_BONUS / 2; | |
598 | ||
599 | prio = p->static_prio - bonus; | |
600 | if (prio < MAX_RT_PRIO) | |
601 | prio = MAX_RT_PRIO; | |
602 | if (prio > MAX_PRIO-1) | |
603 | prio = MAX_PRIO-1; | |
604 | return prio; | |
605 | } | |
606 | ||
607 | /* | |
608 | * __activate_task - move a task to the runqueue. | |
609 | */ | |
610 | static inline void __activate_task(task_t *p, runqueue_t *rq) | |
611 | { | |
612 | enqueue_task(p, rq->active); | |
613 | rq->nr_running++; | |
614 | } | |
615 | ||
616 | /* | |
617 | * __activate_idle_task - move idle task to the _front_ of runqueue. | |
618 | */ | |
619 | static inline void __activate_idle_task(task_t *p, runqueue_t *rq) | |
620 | { | |
621 | enqueue_task_head(p, rq->active); | |
622 | rq->nr_running++; | |
623 | } | |
624 | ||
625 | static void recalc_task_prio(task_t *p, unsigned long long now) | |
626 | { | |
627 | /* Caller must always ensure 'now >= p->timestamp' */ | |
628 | unsigned long long __sleep_time = now - p->timestamp; | |
629 | unsigned long sleep_time; | |
630 | ||
631 | if (__sleep_time > NS_MAX_SLEEP_AVG) | |
632 | sleep_time = NS_MAX_SLEEP_AVG; | |
633 | else | |
634 | sleep_time = (unsigned long)__sleep_time; | |
635 | ||
636 | if (likely(sleep_time > 0)) { | |
637 | /* | |
638 | * User tasks that sleep a long time are categorised as | |
639 | * idle and will get just interactive status to stay active & | |
640 | * prevent them suddenly becoming cpu hogs and starving | |
641 | * other processes. | |
642 | */ | |
643 | if (p->mm && p->activated != -1 && | |
644 | sleep_time > INTERACTIVE_SLEEP(p)) { | |
645 | p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG - | |
646 | DEF_TIMESLICE); | |
647 | } else { | |
648 | /* | |
649 | * The lower the sleep avg a task has the more | |
650 | * rapidly it will rise with sleep time. | |
651 | */ | |
652 | sleep_time *= (MAX_BONUS - CURRENT_BONUS(p)) ? : 1; | |
653 | ||
654 | /* | |
655 | * Tasks waking from uninterruptible sleep are | |
656 | * limited in their sleep_avg rise as they | |
657 | * are likely to be waiting on I/O | |
658 | */ | |
659 | if (p->activated == -1 && p->mm) { | |
660 | if (p->sleep_avg >= INTERACTIVE_SLEEP(p)) | |
661 | sleep_time = 0; | |
662 | else if (p->sleep_avg + sleep_time >= | |
663 | INTERACTIVE_SLEEP(p)) { | |
664 | p->sleep_avg = INTERACTIVE_SLEEP(p); | |
665 | sleep_time = 0; | |
666 | } | |
667 | } | |
668 | ||
669 | /* | |
670 | * This code gives a bonus to interactive tasks. | |
671 | * | |
672 | * The boost works by updating the 'average sleep time' | |
673 | * value here, based on ->timestamp. The more time a | |
674 | * task spends sleeping, the higher the average gets - | |
675 | * and the higher the priority boost gets as well. | |
676 | */ | |
677 | p->sleep_avg += sleep_time; | |
678 | ||
679 | if (p->sleep_avg > NS_MAX_SLEEP_AVG) | |
680 | p->sleep_avg = NS_MAX_SLEEP_AVG; | |
681 | } | |
682 | } | |
683 | ||
684 | p->prio = effective_prio(p); | |
685 | } | |
686 | ||
687 | /* | |
688 | * activate_task - move a task to the runqueue and do priority recalculation | |
689 | * | |
690 | * Update all the scheduling statistics stuff. (sleep average | |
691 | * calculation, priority modifiers, etc.) | |
692 | */ | |
693 | static void activate_task(task_t *p, runqueue_t *rq, int local) | |
694 | { | |
695 | unsigned long long now; | |
696 | ||
697 | now = sched_clock(); | |
698 | #ifdef CONFIG_SMP | |
699 | if (!local) { | |
700 | /* Compensate for drifting sched_clock */ | |
701 | runqueue_t *this_rq = this_rq(); | |
702 | now = (now - this_rq->timestamp_last_tick) | |
703 | + rq->timestamp_last_tick; | |
704 | } | |
705 | #endif | |
706 | ||
707 | recalc_task_prio(p, now); | |
708 | ||
709 | /* | |
710 | * This checks to make sure it's not an uninterruptible task | |
711 | * that is now waking up. | |
712 | */ | |
713 | if (!p->activated) { | |
714 | /* | |
715 | * Tasks which were woken up by interrupts (ie. hw events) | |
716 | * are most likely of interactive nature. So we give them | |
717 | * the credit of extending their sleep time to the period | |
718 | * of time they spend on the runqueue, waiting for execution | |
719 | * on a CPU, first time around: | |
720 | */ | |
721 | if (in_interrupt()) | |
722 | p->activated = 2; | |
723 | else { | |
724 | /* | |
725 | * Normal first-time wakeups get a credit too for | |
726 | * on-runqueue time, but it will be weighted down: | |
727 | */ | |
728 | p->activated = 1; | |
729 | } | |
730 | } | |
731 | p->timestamp = now; | |
732 | ||
733 | __activate_task(p, rq); | |
734 | } | |
735 | ||
736 | /* | |
737 | * deactivate_task - remove a task from the runqueue. | |
738 | */ | |
739 | static void deactivate_task(struct task_struct *p, runqueue_t *rq) | |
740 | { | |
741 | rq->nr_running--; | |
742 | dequeue_task(p, p->array); | |
743 | p->array = NULL; | |
744 | } | |
745 | ||
746 | /* | |
747 | * resched_task - mark a task 'to be rescheduled now'. | |
748 | * | |
749 | * On UP this means the setting of the need_resched flag, on SMP it | |
750 | * might also involve a cross-CPU call to trigger the scheduler on | |
751 | * the target CPU. | |
752 | */ | |
753 | #ifdef CONFIG_SMP | |
754 | static void resched_task(task_t *p) | |
755 | { | |
756 | int need_resched, nrpolling; | |
757 | ||
758 | assert_spin_locked(&task_rq(p)->lock); | |
759 | ||
760 | /* minimise the chance of sending an interrupt to poll_idle() */ | |
761 | nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG); | |
762 | need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED); | |
763 | nrpolling |= test_tsk_thread_flag(p,TIF_POLLING_NRFLAG); | |
764 | ||
765 | if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id())) | |
766 | smp_send_reschedule(task_cpu(p)); | |
767 | } | |
768 | #else | |
769 | static inline void resched_task(task_t *p) | |
770 | { | |
771 | set_tsk_need_resched(p); | |
772 | } | |
773 | #endif | |
774 | ||
775 | /** | |
776 | * task_curr - is this task currently executing on a CPU? | |
777 | * @p: the task in question. | |
778 | */ | |
779 | inline int task_curr(const task_t *p) | |
780 | { | |
781 | return cpu_curr(task_cpu(p)) == p; | |
782 | } | |
783 | ||
784 | #ifdef CONFIG_SMP | |
785 | enum request_type { | |
786 | REQ_MOVE_TASK, | |
787 | REQ_SET_DOMAIN, | |
788 | }; | |
789 | ||
790 | typedef struct { | |
791 | struct list_head list; | |
792 | enum request_type type; | |
793 | ||
794 | /* For REQ_MOVE_TASK */ | |
795 | task_t *task; | |
796 | int dest_cpu; | |
797 | ||
798 | /* For REQ_SET_DOMAIN */ | |
799 | struct sched_domain *sd; | |
800 | ||
801 | struct completion done; | |
802 | } migration_req_t; | |
803 | ||
804 | /* | |
805 | * The task's runqueue lock must be held. | |
806 | * Returns true if you have to wait for migration thread. | |
807 | */ | |
808 | static int migrate_task(task_t *p, int dest_cpu, migration_req_t *req) | |
809 | { | |
810 | runqueue_t *rq = task_rq(p); | |
811 | ||
812 | /* | |
813 | * If the task is not on a runqueue (and not running), then | |
814 | * it is sufficient to simply update the task's cpu field. | |
815 | */ | |
816 | if (!p->array && !task_running(rq, p)) { | |
817 | set_task_cpu(p, dest_cpu); | |
818 | return 0; | |
819 | } | |
820 | ||
821 | init_completion(&req->done); | |
822 | req->type = REQ_MOVE_TASK; | |
823 | req->task = p; | |
824 | req->dest_cpu = dest_cpu; | |
825 | list_add(&req->list, &rq->migration_queue); | |
826 | return 1; | |
827 | } | |
828 | ||
829 | /* | |
830 | * wait_task_inactive - wait for a thread to unschedule. | |
831 | * | |
832 | * The caller must ensure that the task *will* unschedule sometime soon, | |
833 | * else this function might spin for a *long* time. This function can't | |
834 | * be called with interrupts off, or it may introduce deadlock with | |
835 | * smp_call_function() if an IPI is sent by the same process we are | |
836 | * waiting to become inactive. | |
837 | */ | |
838 | void wait_task_inactive(task_t * p) | |
839 | { | |
840 | unsigned long flags; | |
841 | runqueue_t *rq; | |
842 | int preempted; | |
843 | ||
844 | repeat: | |
845 | rq = task_rq_lock(p, &flags); | |
846 | /* Must be off runqueue entirely, not preempted. */ | |
847 | if (unlikely(p->array || task_running(rq, p))) { | |
848 | /* If it's preempted, we yield. It could be a while. */ | |
849 | preempted = !task_running(rq, p); | |
850 | task_rq_unlock(rq, &flags); | |
851 | cpu_relax(); | |
852 | if (preempted) | |
853 | yield(); | |
854 | goto repeat; | |
855 | } | |
856 | task_rq_unlock(rq, &flags); | |
857 | } | |
858 | ||
859 | /*** | |
860 | * kick_process - kick a running thread to enter/exit the kernel | |
861 | * @p: the to-be-kicked thread | |
862 | * | |
863 | * Cause a process which is running on another CPU to enter | |
864 | * kernel-mode, without any delay. (to get signals handled.) | |
865 | * | |
866 | * NOTE: this function doesnt have to take the runqueue lock, | |
867 | * because all it wants to ensure is that the remote task enters | |
868 | * the kernel. If the IPI races and the task has been migrated | |
869 | * to another CPU then no harm is done and the purpose has been | |
870 | * achieved as well. | |
871 | */ | |
872 | void kick_process(task_t *p) | |
873 | { | |
874 | int cpu; | |
875 | ||
876 | preempt_disable(); | |
877 | cpu = task_cpu(p); | |
878 | if ((cpu != smp_processor_id()) && task_curr(p)) | |
879 | smp_send_reschedule(cpu); | |
880 | preempt_enable(); | |
881 | } | |
882 | ||
883 | /* | |
884 | * Return a low guess at the load of a migration-source cpu. | |
885 | * | |
886 | * We want to under-estimate the load of migration sources, to | |
887 | * balance conservatively. | |
888 | */ | |
889 | static inline unsigned long source_load(int cpu) | |
890 | { | |
891 | runqueue_t *rq = cpu_rq(cpu); | |
892 | unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE; | |
893 | ||
894 | return min(rq->cpu_load, load_now); | |
895 | } | |
896 | ||
897 | /* | |
898 | * Return a high guess at the load of a migration-target cpu | |
899 | */ | |
900 | static inline unsigned long target_load(int cpu) | |
901 | { | |
902 | runqueue_t *rq = cpu_rq(cpu); | |
903 | unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE; | |
904 | ||
905 | return max(rq->cpu_load, load_now); | |
906 | } | |
907 | ||
908 | #endif | |
909 | ||
910 | /* | |
911 | * wake_idle() will wake a task on an idle cpu if task->cpu is | |
912 | * not idle and an idle cpu is available. The span of cpus to | |
913 | * search starts with cpus closest then further out as needed, | |
914 | * so we always favor a closer, idle cpu. | |
915 | * | |
916 | * Returns the CPU we should wake onto. | |
917 | */ | |
918 | #if defined(ARCH_HAS_SCHED_WAKE_IDLE) | |
919 | static int wake_idle(int cpu, task_t *p) | |
920 | { | |
921 | cpumask_t tmp; | |
922 | struct sched_domain *sd; | |
923 | int i; | |
924 | ||
925 | if (idle_cpu(cpu)) | |
926 | return cpu; | |
927 | ||
928 | for_each_domain(cpu, sd) { | |
929 | if (sd->flags & SD_WAKE_IDLE) { | |
930 | cpus_and(tmp, sd->span, cpu_online_map); | |
931 | cpus_and(tmp, tmp, p->cpus_allowed); | |
932 | for_each_cpu_mask(i, tmp) { | |
933 | if (idle_cpu(i)) | |
934 | return i; | |
935 | } | |
936 | } | |
937 | else break; | |
938 | } | |
939 | return cpu; | |
940 | } | |
941 | #else | |
942 | static inline int wake_idle(int cpu, task_t *p) | |
943 | { | |
944 | return cpu; | |
945 | } | |
946 | #endif | |
947 | ||
948 | /*** | |
949 | * try_to_wake_up - wake up a thread | |
950 | * @p: the to-be-woken-up thread | |
951 | * @state: the mask of task states that can be woken | |
952 | * @sync: do a synchronous wakeup? | |
953 | * | |
954 | * Put it on the run-queue if it's not already there. The "current" | |
955 | * thread is always on the run-queue (except when the actual | |
956 | * re-schedule is in progress), and as such you're allowed to do | |
957 | * the simpler "current->state = TASK_RUNNING" to mark yourself | |
958 | * runnable without the overhead of this. | |
959 | * | |
960 | * returns failure only if the task is already active. | |
961 | */ | |
962 | static int try_to_wake_up(task_t * p, unsigned int state, int sync) | |
963 | { | |
964 | int cpu, this_cpu, success = 0; | |
965 | unsigned long flags; | |
966 | long old_state; | |
967 | runqueue_t *rq; | |
968 | #ifdef CONFIG_SMP | |
969 | unsigned long load, this_load; | |
970 | struct sched_domain *sd; | |
971 | int new_cpu; | |
972 | #endif | |
973 | ||
974 | rq = task_rq_lock(p, &flags); | |
975 | old_state = p->state; | |
976 | if (!(old_state & state)) | |
977 | goto out; | |
978 | ||
979 | if (p->array) | |
980 | goto out_running; | |
981 | ||
982 | cpu = task_cpu(p); | |
983 | this_cpu = smp_processor_id(); | |
984 | ||
985 | #ifdef CONFIG_SMP | |
986 | if (unlikely(task_running(rq, p))) | |
987 | goto out_activate; | |
988 | ||
989 | #ifdef CONFIG_SCHEDSTATS | |
990 | schedstat_inc(rq, ttwu_cnt); | |
991 | if (cpu == this_cpu) { | |
992 | schedstat_inc(rq, ttwu_local); | |
993 | } else { | |
994 | for_each_domain(this_cpu, sd) { | |
995 | if (cpu_isset(cpu, sd->span)) { | |
996 | schedstat_inc(sd, ttwu_wake_remote); | |
997 | break; | |
998 | } | |
999 | } | |
1000 | } | |
1001 | #endif | |
1002 | ||
1003 | new_cpu = cpu; | |
1004 | if (cpu == this_cpu || unlikely(!cpu_isset(this_cpu, p->cpus_allowed))) | |
1005 | goto out_set_cpu; | |
1006 | ||
1007 | load = source_load(cpu); | |
1008 | this_load = target_load(this_cpu); | |
1009 | ||
1010 | /* | |
1011 | * If sync wakeup then subtract the (maximum possible) effect of | |
1012 | * the currently running task from the load of the current CPU: | |
1013 | */ | |
1014 | if (sync) | |
1015 | this_load -= SCHED_LOAD_SCALE; | |
1016 | ||
1017 | /* Don't pull the task off an idle CPU to a busy one */ | |
1018 | if (load < SCHED_LOAD_SCALE/2 && this_load > SCHED_LOAD_SCALE/2) | |
1019 | goto out_set_cpu; | |
1020 | ||
1021 | new_cpu = this_cpu; /* Wake to this CPU if we can */ | |
1022 | ||
1023 | /* | |
1024 | * Scan domains for affine wakeup and passive balancing | |
1025 | * possibilities. | |
1026 | */ | |
1027 | for_each_domain(this_cpu, sd) { | |
1028 | unsigned int imbalance; | |
1029 | /* | |
1030 | * Start passive balancing when half the imbalance_pct | |
1031 | * limit is reached. | |
1032 | */ | |
1033 | imbalance = sd->imbalance_pct + (sd->imbalance_pct - 100) / 2; | |
1034 | ||
1035 | if ((sd->flags & SD_WAKE_AFFINE) && | |
1036 | !task_hot(p, rq->timestamp_last_tick, sd)) { | |
1037 | /* | |
1038 | * This domain has SD_WAKE_AFFINE and p is cache cold | |
1039 | * in this domain. | |
1040 | */ | |
1041 | if (cpu_isset(cpu, sd->span)) { | |
1042 | schedstat_inc(sd, ttwu_move_affine); | |
1043 | goto out_set_cpu; | |
1044 | } | |
1045 | } else if ((sd->flags & SD_WAKE_BALANCE) && | |
1046 | imbalance*this_load <= 100*load) { | |
1047 | /* | |
1048 | * This domain has SD_WAKE_BALANCE and there is | |
1049 | * an imbalance. | |
1050 | */ | |
1051 | if (cpu_isset(cpu, sd->span)) { | |
1052 | schedstat_inc(sd, ttwu_move_balance); | |
1053 | goto out_set_cpu; | |
1054 | } | |
1055 | } | |
1056 | } | |
1057 | ||
1058 | new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */ | |
1059 | out_set_cpu: | |
1060 | new_cpu = wake_idle(new_cpu, p); | |
1061 | if (new_cpu != cpu) { | |
1062 | set_task_cpu(p, new_cpu); | |
1063 | task_rq_unlock(rq, &flags); | |
1064 | /* might preempt at this point */ | |
1065 | rq = task_rq_lock(p, &flags); | |
1066 | old_state = p->state; | |
1067 | if (!(old_state & state)) | |
1068 | goto out; | |
1069 | if (p->array) | |
1070 | goto out_running; | |
1071 | ||
1072 | this_cpu = smp_processor_id(); | |
1073 | cpu = task_cpu(p); | |
1074 | } | |
1075 | ||
1076 | out_activate: | |
1077 | #endif /* CONFIG_SMP */ | |
1078 | if (old_state == TASK_UNINTERRUPTIBLE) { | |
1079 | rq->nr_uninterruptible--; | |
1080 | /* | |
1081 | * Tasks on involuntary sleep don't earn | |
1082 | * sleep_avg beyond just interactive state. | |
1083 | */ | |
1084 | p->activated = -1; | |
1085 | } | |
1086 | ||
1087 | /* | |
1088 | * Sync wakeups (i.e. those types of wakeups where the waker | |
1089 | * has indicated that it will leave the CPU in short order) | |
1090 | * don't trigger a preemption, if the woken up task will run on | |
1091 | * this cpu. (in this case the 'I will reschedule' promise of | |
1092 | * the waker guarantees that the freshly woken up task is going | |
1093 | * to be considered on this CPU.) | |
1094 | */ | |
1095 | activate_task(p, rq, cpu == this_cpu); | |
1096 | if (!sync || cpu != this_cpu) { | |
1097 | if (TASK_PREEMPTS_CURR(p, rq)) | |
1098 | resched_task(rq->curr); | |
1099 | } | |
1100 | success = 1; | |
1101 | ||
1102 | out_running: | |
1103 | p->state = TASK_RUNNING; | |
1104 | out: | |
1105 | task_rq_unlock(rq, &flags); | |
1106 | ||
1107 | return success; | |
1108 | } | |
1109 | ||
1110 | int fastcall wake_up_process(task_t * p) | |
1111 | { | |
1112 | return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED | | |
1113 | TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0); | |
1114 | } | |
1115 | ||
1116 | EXPORT_SYMBOL(wake_up_process); | |
1117 | ||
1118 | int fastcall wake_up_state(task_t *p, unsigned int state) | |
1119 | { | |
1120 | return try_to_wake_up(p, state, 0); | |
1121 | } | |
1122 | ||
1123 | #ifdef CONFIG_SMP | |
1124 | static int find_idlest_cpu(struct task_struct *p, int this_cpu, | |
1125 | struct sched_domain *sd); | |
1126 | #endif | |
1127 | ||
1128 | /* | |
1129 | * Perform scheduler related setup for a newly forked process p. | |
1130 | * p is forked by current. | |
1131 | */ | |
1132 | void fastcall sched_fork(task_t *p) | |
1133 | { | |
1134 | /* | |
1135 | * We mark the process as running here, but have not actually | |
1136 | * inserted it onto the runqueue yet. This guarantees that | |
1137 | * nobody will actually run it, and a signal or other external | |
1138 | * event cannot wake it up and insert it on the runqueue either. | |
1139 | */ | |
1140 | p->state = TASK_RUNNING; | |
1141 | INIT_LIST_HEAD(&p->run_list); | |
1142 | p->array = NULL; | |
1143 | spin_lock_init(&p->switch_lock); | |
1144 | #ifdef CONFIG_SCHEDSTATS | |
1145 | memset(&p->sched_info, 0, sizeof(p->sched_info)); | |
1146 | #endif | |
1147 | #ifdef CONFIG_PREEMPT | |
1148 | /* | |
1149 | * During context-switch we hold precisely one spinlock, which | |
1150 | * schedule_tail drops. (in the common case it's this_rq()->lock, | |
1151 | * but it also can be p->switch_lock.) So we compensate with a count | |
1152 | * of 1. Also, we want to start with kernel preemption disabled. | |
1153 | */ | |
1154 | p->thread_info->preempt_count = 1; | |
1155 | #endif | |
1156 | /* | |
1157 | * Share the timeslice between parent and child, thus the | |
1158 | * total amount of pending timeslices in the system doesn't change, | |
1159 | * resulting in more scheduling fairness. | |
1160 | */ | |
1161 | local_irq_disable(); | |
1162 | p->time_slice = (current->time_slice + 1) >> 1; | |
1163 | /* | |
1164 | * The remainder of the first timeslice might be recovered by | |
1165 | * the parent if the child exits early enough. | |
1166 | */ | |
1167 | p->first_time_slice = 1; | |
1168 | current->time_slice >>= 1; | |
1169 | p->timestamp = sched_clock(); | |
1170 | if (unlikely(!current->time_slice)) { | |
1171 | /* | |
1172 | * This case is rare, it happens when the parent has only | |
1173 | * a single jiffy left from its timeslice. Taking the | |
1174 | * runqueue lock is not a problem. | |
1175 | */ | |
1176 | current->time_slice = 1; | |
1177 | preempt_disable(); | |
1178 | scheduler_tick(); | |
1179 | local_irq_enable(); | |
1180 | preempt_enable(); | |
1181 | } else | |
1182 | local_irq_enable(); | |
1183 | } | |
1184 | ||
1185 | /* | |
1186 | * wake_up_new_task - wake up a newly created task for the first time. | |
1187 | * | |
1188 | * This function will do some initial scheduler statistics housekeeping | |
1189 | * that must be done for every newly created context, then puts the task | |
1190 | * on the runqueue and wakes it. | |
1191 | */ | |
1192 | void fastcall wake_up_new_task(task_t * p, unsigned long clone_flags) | |
1193 | { | |
1194 | unsigned long flags; | |
1195 | int this_cpu, cpu; | |
1196 | runqueue_t *rq, *this_rq; | |
1197 | ||
1198 | rq = task_rq_lock(p, &flags); | |
1199 | cpu = task_cpu(p); | |
1200 | this_cpu = smp_processor_id(); | |
1201 | ||
1202 | BUG_ON(p->state != TASK_RUNNING); | |
1203 | ||
1204 | /* | |
1205 | * We decrease the sleep average of forking parents | |
1206 | * and children as well, to keep max-interactive tasks | |
1207 | * from forking tasks that are max-interactive. The parent | |
1208 | * (current) is done further down, under its lock. | |
1209 | */ | |
1210 | p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) * | |
1211 | CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS); | |
1212 | ||
1213 | p->prio = effective_prio(p); | |
1214 | ||
1215 | if (likely(cpu == this_cpu)) { | |
1216 | if (!(clone_flags & CLONE_VM)) { | |
1217 | /* | |
1218 | * The VM isn't cloned, so we're in a good position to | |
1219 | * do child-runs-first in anticipation of an exec. This | |
1220 | * usually avoids a lot of COW overhead. | |
1221 | */ | |
1222 | if (unlikely(!current->array)) | |
1223 | __activate_task(p, rq); | |
1224 | else { | |
1225 | p->prio = current->prio; | |
1226 | list_add_tail(&p->run_list, ¤t->run_list); | |
1227 | p->array = current->array; | |
1228 | p->array->nr_active++; | |
1229 | rq->nr_running++; | |
1230 | } | |
1231 | set_need_resched(); | |
1232 | } else | |
1233 | /* Run child last */ | |
1234 | __activate_task(p, rq); | |
1235 | /* | |
1236 | * We skip the following code due to cpu == this_cpu | |
1237 | * | |
1238 | * task_rq_unlock(rq, &flags); | |
1239 | * this_rq = task_rq_lock(current, &flags); | |
1240 | */ | |
1241 | this_rq = rq; | |
1242 | } else { | |
1243 | this_rq = cpu_rq(this_cpu); | |
1244 | ||
1245 | /* | |
1246 | * Not the local CPU - must adjust timestamp. This should | |
1247 | * get optimised away in the !CONFIG_SMP case. | |
1248 | */ | |
1249 | p->timestamp = (p->timestamp - this_rq->timestamp_last_tick) | |
1250 | + rq->timestamp_last_tick; | |
1251 | __activate_task(p, rq); | |
1252 | if (TASK_PREEMPTS_CURR(p, rq)) | |
1253 | resched_task(rq->curr); | |
1254 | ||
1255 | /* | |
1256 | * Parent and child are on different CPUs, now get the | |
1257 | * parent runqueue to update the parent's ->sleep_avg: | |
1258 | */ | |
1259 | task_rq_unlock(rq, &flags); | |
1260 | this_rq = task_rq_lock(current, &flags); | |
1261 | } | |
1262 | current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) * | |
1263 | PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS); | |
1264 | task_rq_unlock(this_rq, &flags); | |
1265 | } | |
1266 | ||
1267 | /* | |
1268 | * Potentially available exiting-child timeslices are | |
1269 | * retrieved here - this way the parent does not get | |
1270 | * penalized for creating too many threads. | |
1271 | * | |
1272 | * (this cannot be used to 'generate' timeslices | |
1273 | * artificially, because any timeslice recovered here | |
1274 | * was given away by the parent in the first place.) | |
1275 | */ | |
1276 | void fastcall sched_exit(task_t * p) | |
1277 | { | |
1278 | unsigned long flags; | |
1279 | runqueue_t *rq; | |
1280 | ||
1281 | /* | |
1282 | * If the child was a (relative-) CPU hog then decrease | |
1283 | * the sleep_avg of the parent as well. | |
1284 | */ | |
1285 | rq = task_rq_lock(p->parent, &flags); | |
1286 | if (p->first_time_slice) { | |
1287 | p->parent->time_slice += p->time_slice; | |
1288 | if (unlikely(p->parent->time_slice > task_timeslice(p))) | |
1289 | p->parent->time_slice = task_timeslice(p); | |
1290 | } | |
1291 | if (p->sleep_avg < p->parent->sleep_avg) | |
1292 | p->parent->sleep_avg = p->parent->sleep_avg / | |
1293 | (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg / | |
1294 | (EXIT_WEIGHT + 1); | |
1295 | task_rq_unlock(rq, &flags); | |
1296 | } | |
1297 | ||
1298 | /** | |
1299 | * finish_task_switch - clean up after a task-switch | |
1300 | * @prev: the thread we just switched away from. | |
1301 | * | |
1302 | * We enter this with the runqueue still locked, and finish_arch_switch() | |
1303 | * will unlock it along with doing any other architecture-specific cleanup | |
1304 | * actions. | |
1305 | * | |
1306 | * Note that we may have delayed dropping an mm in context_switch(). If | |
1307 | * so, we finish that here outside of the runqueue lock. (Doing it | |
1308 | * with the lock held can cause deadlocks; see schedule() for | |
1309 | * details.) | |
1310 | */ | |
1311 | static inline void finish_task_switch(task_t *prev) | |
1312 | __releases(rq->lock) | |
1313 | { | |
1314 | runqueue_t *rq = this_rq(); | |
1315 | struct mm_struct *mm = rq->prev_mm; | |
1316 | unsigned long prev_task_flags; | |
1317 | ||
1318 | rq->prev_mm = NULL; | |
1319 | ||
1320 | /* | |
1321 | * A task struct has one reference for the use as "current". | |
1322 | * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and | |
1323 | * calls schedule one last time. The schedule call will never return, | |
1324 | * and the scheduled task must drop that reference. | |
1325 | * The test for EXIT_ZOMBIE must occur while the runqueue locks are | |
1326 | * still held, otherwise prev could be scheduled on another cpu, die | |
1327 | * there before we look at prev->state, and then the reference would | |
1328 | * be dropped twice. | |
1329 | * Manfred Spraul <manfred@colorfullife.com> | |
1330 | */ | |
1331 | prev_task_flags = prev->flags; | |
1332 | finish_arch_switch(rq, prev); | |
1333 | if (mm) | |
1334 | mmdrop(mm); | |
1335 | if (unlikely(prev_task_flags & PF_DEAD)) | |
1336 | put_task_struct(prev); | |
1337 | } | |
1338 | ||
1339 | /** | |
1340 | * schedule_tail - first thing a freshly forked thread must call. | |
1341 | * @prev: the thread we just switched away from. | |
1342 | */ | |
1343 | asmlinkage void schedule_tail(task_t *prev) | |
1344 | __releases(rq->lock) | |
1345 | { | |
1346 | finish_task_switch(prev); | |
1347 | ||
1348 | if (current->set_child_tid) | |
1349 | put_user(current->pid, current->set_child_tid); | |
1350 | } | |
1351 | ||
1352 | /* | |
1353 | * context_switch - switch to the new MM and the new | |
1354 | * thread's register state. | |
1355 | */ | |
1356 | static inline | |
1357 | task_t * context_switch(runqueue_t *rq, task_t *prev, task_t *next) | |
1358 | { | |
1359 | struct mm_struct *mm = next->mm; | |
1360 | struct mm_struct *oldmm = prev->active_mm; | |
1361 | ||
1362 | if (unlikely(!mm)) { | |
1363 | next->active_mm = oldmm; | |
1364 | atomic_inc(&oldmm->mm_count); | |
1365 | enter_lazy_tlb(oldmm, next); | |
1366 | } else | |
1367 | switch_mm(oldmm, mm, next); | |
1368 | ||
1369 | if (unlikely(!prev->mm)) { | |
1370 | prev->active_mm = NULL; | |
1371 | WARN_ON(rq->prev_mm); | |
1372 | rq->prev_mm = oldmm; | |
1373 | } | |
1374 | ||
1375 | /* Here we just switch the register state and the stack. */ | |
1376 | switch_to(prev, next, prev); | |
1377 | ||
1378 | return prev; | |
1379 | } | |
1380 | ||
1381 | /* | |
1382 | * nr_running, nr_uninterruptible and nr_context_switches: | |
1383 | * | |
1384 | * externally visible scheduler statistics: current number of runnable | |
1385 | * threads, current number of uninterruptible-sleeping threads, total | |
1386 | * number of context switches performed since bootup. | |
1387 | */ | |
1388 | unsigned long nr_running(void) | |
1389 | { | |
1390 | unsigned long i, sum = 0; | |
1391 | ||
1392 | for_each_online_cpu(i) | |
1393 | sum += cpu_rq(i)->nr_running; | |
1394 | ||
1395 | return sum; | |
1396 | } | |
1397 | ||
1398 | unsigned long nr_uninterruptible(void) | |
1399 | { | |
1400 | unsigned long i, sum = 0; | |
1401 | ||
1402 | for_each_cpu(i) | |
1403 | sum += cpu_rq(i)->nr_uninterruptible; | |
1404 | ||
1405 | /* | |
1406 | * Since we read the counters lockless, it might be slightly | |
1407 | * inaccurate. Do not allow it to go below zero though: | |
1408 | */ | |
1409 | if (unlikely((long)sum < 0)) | |
1410 | sum = 0; | |
1411 | ||
1412 | return sum; | |
1413 | } | |
1414 | ||
1415 | unsigned long long nr_context_switches(void) | |
1416 | { | |
1417 | unsigned long long i, sum = 0; | |
1418 | ||
1419 | for_each_cpu(i) | |
1420 | sum += cpu_rq(i)->nr_switches; | |
1421 | ||
1422 | return sum; | |
1423 | } | |
1424 | ||
1425 | unsigned long nr_iowait(void) | |
1426 | { | |
1427 | unsigned long i, sum = 0; | |
1428 | ||
1429 | for_each_cpu(i) | |
1430 | sum += atomic_read(&cpu_rq(i)->nr_iowait); | |
1431 | ||
1432 | return sum; | |
1433 | } | |
1434 | ||
1435 | #ifdef CONFIG_SMP | |
1436 | ||
1437 | /* | |
1438 | * double_rq_lock - safely lock two runqueues | |
1439 | * | |
1440 | * Note this does not disable interrupts like task_rq_lock, | |
1441 | * you need to do so manually before calling. | |
1442 | */ | |
1443 | static void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2) | |
1444 | __acquires(rq1->lock) | |
1445 | __acquires(rq2->lock) | |
1446 | { | |
1447 | if (rq1 == rq2) { | |
1448 | spin_lock(&rq1->lock); | |
1449 | __acquire(rq2->lock); /* Fake it out ;) */ | |
1450 | } else { | |
1451 | if (rq1 < rq2) { | |
1452 | spin_lock(&rq1->lock); | |
1453 | spin_lock(&rq2->lock); | |
1454 | } else { | |
1455 | spin_lock(&rq2->lock); | |
1456 | spin_lock(&rq1->lock); | |
1457 | } | |
1458 | } | |
1459 | } | |
1460 | ||
1461 | /* | |
1462 | * double_rq_unlock - safely unlock two runqueues | |
1463 | * | |
1464 | * Note this does not restore interrupts like task_rq_unlock, | |
1465 | * you need to do so manually after calling. | |
1466 | */ | |
1467 | static void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2) | |
1468 | __releases(rq1->lock) | |
1469 | __releases(rq2->lock) | |
1470 | { | |
1471 | spin_unlock(&rq1->lock); | |
1472 | if (rq1 != rq2) | |
1473 | spin_unlock(&rq2->lock); | |
1474 | else | |
1475 | __release(rq2->lock); | |
1476 | } | |
1477 | ||
1478 | /* | |
1479 | * double_lock_balance - lock the busiest runqueue, this_rq is locked already. | |
1480 | */ | |
1481 | static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest) | |
1482 | __releases(this_rq->lock) | |
1483 | __acquires(busiest->lock) | |
1484 | __acquires(this_rq->lock) | |
1485 | { | |
1486 | if (unlikely(!spin_trylock(&busiest->lock))) { | |
1487 | if (busiest < this_rq) { | |
1488 | spin_unlock(&this_rq->lock); | |
1489 | spin_lock(&busiest->lock); | |
1490 | spin_lock(&this_rq->lock); | |
1491 | } else | |
1492 | spin_lock(&busiest->lock); | |
1493 | } | |
1494 | } | |
1495 | ||
1496 | /* | |
1497 | * find_idlest_cpu - find the least busy runqueue. | |
1498 | */ | |
1499 | static int find_idlest_cpu(struct task_struct *p, int this_cpu, | |
1500 | struct sched_domain *sd) | |
1501 | { | |
1502 | unsigned long load, min_load, this_load; | |
1503 | int i, min_cpu; | |
1504 | cpumask_t mask; | |
1505 | ||
1506 | min_cpu = UINT_MAX; | |
1507 | min_load = ULONG_MAX; | |
1508 | ||
1509 | cpus_and(mask, sd->span, p->cpus_allowed); | |
1510 | ||
1511 | for_each_cpu_mask(i, mask) { | |
1512 | load = target_load(i); | |
1513 | ||
1514 | if (load < min_load) { | |
1515 | min_cpu = i; | |
1516 | min_load = load; | |
1517 | ||
1518 | /* break out early on an idle CPU: */ | |
1519 | if (!min_load) | |
1520 | break; | |
1521 | } | |
1522 | } | |
1523 | ||
1524 | /* add +1 to account for the new task */ | |
1525 | this_load = source_load(this_cpu) + SCHED_LOAD_SCALE; | |
1526 | ||
1527 | /* | |
1528 | * Would with the addition of the new task to the | |
1529 | * current CPU there be an imbalance between this | |
1530 | * CPU and the idlest CPU? | |
1531 | * | |
1532 | * Use half of the balancing threshold - new-context is | |
1533 | * a good opportunity to balance. | |
1534 | */ | |
1535 | if (min_load*(100 + (sd->imbalance_pct-100)/2) < this_load*100) | |
1536 | return min_cpu; | |
1537 | ||
1538 | return this_cpu; | |
1539 | } | |
1540 | ||
1541 | /* | |
1542 | * If dest_cpu is allowed for this process, migrate the task to it. | |
1543 | * This is accomplished by forcing the cpu_allowed mask to only | |
1544 | * allow dest_cpu, which will force the cpu onto dest_cpu. Then | |
1545 | * the cpu_allowed mask is restored. | |
1546 | */ | |
1547 | static void sched_migrate_task(task_t *p, int dest_cpu) | |
1548 | { | |
1549 | migration_req_t req; | |
1550 | runqueue_t *rq; | |
1551 | unsigned long flags; | |
1552 | ||
1553 | rq = task_rq_lock(p, &flags); | |
1554 | if (!cpu_isset(dest_cpu, p->cpus_allowed) | |
1555 | || unlikely(cpu_is_offline(dest_cpu))) | |
1556 | goto out; | |
1557 | ||
1558 | /* force the process onto the specified CPU */ | |
1559 | if (migrate_task(p, dest_cpu, &req)) { | |
1560 | /* Need to wait for migration thread (might exit: take ref). */ | |
1561 | struct task_struct *mt = rq->migration_thread; | |
1562 | get_task_struct(mt); | |
1563 | task_rq_unlock(rq, &flags); | |
1564 | wake_up_process(mt); | |
1565 | put_task_struct(mt); | |
1566 | wait_for_completion(&req.done); | |
1567 | return; | |
1568 | } | |
1569 | out: | |
1570 | task_rq_unlock(rq, &flags); | |
1571 | } | |
1572 | ||
1573 | /* | |
1574 | * sched_exec(): find the highest-level, exec-balance-capable | |
1575 | * domain and try to migrate the task to the least loaded CPU. | |
1576 | * | |
1577 | * execve() is a valuable balancing opportunity, because at this point | |
1578 | * the task has the smallest effective memory and cache footprint. | |
1579 | */ | |
1580 | void sched_exec(void) | |
1581 | { | |
1582 | struct sched_domain *tmp, *sd = NULL; | |
1583 | int new_cpu, this_cpu = get_cpu(); | |
1584 | ||
1585 | /* Prefer the current CPU if there's only this task running */ | |
1586 | if (this_rq()->nr_running <= 1) | |
1587 | goto out; | |
1588 | ||
1589 | for_each_domain(this_cpu, tmp) | |
1590 | if (tmp->flags & SD_BALANCE_EXEC) | |
1591 | sd = tmp; | |
1592 | ||
1593 | if (sd) { | |
1594 | schedstat_inc(sd, sbe_attempts); | |
1595 | new_cpu = find_idlest_cpu(current, this_cpu, sd); | |
1596 | if (new_cpu != this_cpu) { | |
1597 | schedstat_inc(sd, sbe_pushed); | |
1598 | put_cpu(); | |
1599 | sched_migrate_task(current, new_cpu); | |
1600 | return; | |
1601 | } | |
1602 | } | |
1603 | out: | |
1604 | put_cpu(); | |
1605 | } | |
1606 | ||
1607 | /* | |
1608 | * pull_task - move a task from a remote runqueue to the local runqueue. | |
1609 | * Both runqueues must be locked. | |
1610 | */ | |
1611 | static inline | |
1612 | void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p, | |
1613 | runqueue_t *this_rq, prio_array_t *this_array, int this_cpu) | |
1614 | { | |
1615 | dequeue_task(p, src_array); | |
1616 | src_rq->nr_running--; | |
1617 | set_task_cpu(p, this_cpu); | |
1618 | this_rq->nr_running++; | |
1619 | enqueue_task(p, this_array); | |
1620 | p->timestamp = (p->timestamp - src_rq->timestamp_last_tick) | |
1621 | + this_rq->timestamp_last_tick; | |
1622 | /* | |
1623 | * Note that idle threads have a prio of MAX_PRIO, for this test | |
1624 | * to be always true for them. | |
1625 | */ | |
1626 | if (TASK_PREEMPTS_CURR(p, this_rq)) | |
1627 | resched_task(this_rq->curr); | |
1628 | } | |
1629 | ||
1630 | /* | |
1631 | * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? | |
1632 | */ | |
1633 | static inline | |
1634 | int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu, | |
1635 | struct sched_domain *sd, enum idle_type idle) | |
1636 | { | |
1637 | /* | |
1638 | * We do not migrate tasks that are: | |
1639 | * 1) running (obviously), or | |
1640 | * 2) cannot be migrated to this CPU due to cpus_allowed, or | |
1641 | * 3) are cache-hot on their current CPU. | |
1642 | */ | |
1643 | if (task_running(rq, p)) | |
1644 | return 0; | |
1645 | if (!cpu_isset(this_cpu, p->cpus_allowed)) | |
1646 | return 0; | |
1647 | ||
1648 | /* | |
1649 | * Aggressive migration if: | |
1650 | * 1) the [whole] cpu is idle, or | |
1651 | * 2) too many balance attempts have failed. | |
1652 | */ | |
1653 | ||
1654 | if (cpu_and_siblings_are_idle(this_cpu) || \ | |
1655 | sd->nr_balance_failed > sd->cache_nice_tries) | |
1656 | return 1; | |
1657 | ||
1658 | if (task_hot(p, rq->timestamp_last_tick, sd)) | |
1659 | return 0; | |
1660 | return 1; | |
1661 | } | |
1662 | ||
1663 | /* | |
1664 | * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq, | |
1665 | * as part of a balancing operation within "domain". Returns the number of | |
1666 | * tasks moved. | |
1667 | * | |
1668 | * Called with both runqueues locked. | |
1669 | */ | |
1670 | static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest, | |
1671 | unsigned long max_nr_move, struct sched_domain *sd, | |
1672 | enum idle_type idle) | |
1673 | { | |
1674 | prio_array_t *array, *dst_array; | |
1675 | struct list_head *head, *curr; | |
1676 | int idx, pulled = 0; | |
1677 | task_t *tmp; | |
1678 | ||
1679 | if (max_nr_move <= 0 || busiest->nr_running <= 1) | |
1680 | goto out; | |
1681 | ||
1682 | /* | |
1683 | * We first consider expired tasks. Those will likely not be | |
1684 | * executed in the near future, and they are most likely to | |
1685 | * be cache-cold, thus switching CPUs has the least effect | |
1686 | * on them. | |
1687 | */ | |
1688 | if (busiest->expired->nr_active) { | |
1689 | array = busiest->expired; | |
1690 | dst_array = this_rq->expired; | |
1691 | } else { | |
1692 | array = busiest->active; | |
1693 | dst_array = this_rq->active; | |
1694 | } | |
1695 | ||
1696 | new_array: | |
1697 | /* Start searching at priority 0: */ | |
1698 | idx = 0; | |
1699 | skip_bitmap: | |
1700 | if (!idx) | |
1701 | idx = sched_find_first_bit(array->bitmap); | |
1702 | else | |
1703 | idx = find_next_bit(array->bitmap, MAX_PRIO, idx); | |
1704 | if (idx >= MAX_PRIO) { | |
1705 | if (array == busiest->expired && busiest->active->nr_active) { | |
1706 | array = busiest->active; | |
1707 | dst_array = this_rq->active; | |
1708 | goto new_array; | |
1709 | } | |
1710 | goto out; | |
1711 | } | |
1712 | ||
1713 | head = array->queue + idx; | |
1714 | curr = head->prev; | |
1715 | skip_queue: | |
1716 | tmp = list_entry(curr, task_t, run_list); | |
1717 | ||
1718 | curr = curr->prev; | |
1719 | ||
1720 | if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle)) { | |
1721 | if (curr != head) | |
1722 | goto skip_queue; | |
1723 | idx++; | |
1724 | goto skip_bitmap; | |
1725 | } | |
1726 | ||
1727 | #ifdef CONFIG_SCHEDSTATS | |
1728 | if (task_hot(tmp, busiest->timestamp_last_tick, sd)) | |
1729 | schedstat_inc(sd, lb_hot_gained[idle]); | |
1730 | #endif | |
1731 | ||
1732 | pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu); | |
1733 | pulled++; | |
1734 | ||
1735 | /* We only want to steal up to the prescribed number of tasks. */ | |
1736 | if (pulled < max_nr_move) { | |
1737 | if (curr != head) | |
1738 | goto skip_queue; | |
1739 | idx++; | |
1740 | goto skip_bitmap; | |
1741 | } | |
1742 | out: | |
1743 | /* | |
1744 | * Right now, this is the only place pull_task() is called, | |
1745 | * so we can safely collect pull_task() stats here rather than | |
1746 | * inside pull_task(). | |
1747 | */ | |
1748 | schedstat_add(sd, lb_gained[idle], pulled); | |
1749 | return pulled; | |
1750 | } | |
1751 | ||
1752 | /* | |
1753 | * find_busiest_group finds and returns the busiest CPU group within the | |
1754 | * domain. It calculates and returns the number of tasks which should be | |
1755 | * moved to restore balance via the imbalance parameter. | |
1756 | */ | |
1757 | static struct sched_group * | |
1758 | find_busiest_group(struct sched_domain *sd, int this_cpu, | |
1759 | unsigned long *imbalance, enum idle_type idle) | |
1760 | { | |
1761 | struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups; | |
1762 | unsigned long max_load, avg_load, total_load, this_load, total_pwr; | |
1763 | ||
1764 | max_load = this_load = total_load = total_pwr = 0; | |
1765 | ||
1766 | do { | |
1767 | unsigned long load; | |
1768 | int local_group; | |
1769 | int i; | |
1770 | ||
1771 | local_group = cpu_isset(this_cpu, group->cpumask); | |
1772 | ||
1773 | /* Tally up the load of all CPUs in the group */ | |
1774 | avg_load = 0; | |
1775 | ||
1776 | for_each_cpu_mask(i, group->cpumask) { | |
1777 | /* Bias balancing toward cpus of our domain */ | |
1778 | if (local_group) | |
1779 | load = target_load(i); | |
1780 | else | |
1781 | load = source_load(i); | |
1782 | ||
1783 | avg_load += load; | |
1784 | } | |
1785 | ||
1786 | total_load += avg_load; | |
1787 | total_pwr += group->cpu_power; | |
1788 | ||
1789 | /* Adjust by relative CPU power of the group */ | |
1790 | avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power; | |
1791 | ||
1792 | if (local_group) { | |
1793 | this_load = avg_load; | |
1794 | this = group; | |
1795 | goto nextgroup; | |
1796 | } else if (avg_load > max_load) { | |
1797 | max_load = avg_load; | |
1798 | busiest = group; | |
1799 | } | |
1800 | nextgroup: | |
1801 | group = group->next; | |
1802 | } while (group != sd->groups); | |
1803 | ||
1804 | if (!busiest || this_load >= max_load) | |
1805 | goto out_balanced; | |
1806 | ||
1807 | avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr; | |
1808 | ||
1809 | if (this_load >= avg_load || | |
1810 | 100*max_load <= sd->imbalance_pct*this_load) | |
1811 | goto out_balanced; | |
1812 | ||
1813 | /* | |
1814 | * We're trying to get all the cpus to the average_load, so we don't | |
1815 | * want to push ourselves above the average load, nor do we wish to | |
1816 | * reduce the max loaded cpu below the average load, as either of these | |
1817 | * actions would just result in more rebalancing later, and ping-pong | |
1818 | * tasks around. Thus we look for the minimum possible imbalance. | |
1819 | * Negative imbalances (*we* are more loaded than anyone else) will | |
1820 | * be counted as no imbalance for these purposes -- we can't fix that | |
1821 | * by pulling tasks to us. Be careful of negative numbers as they'll | |
1822 | * appear as very large values with unsigned longs. | |
1823 | */ | |
1824 | /* How much load to actually move to equalise the imbalance */ | |
1825 | *imbalance = min((max_load - avg_load) * busiest->cpu_power, | |
1826 | (avg_load - this_load) * this->cpu_power) | |
1827 | / SCHED_LOAD_SCALE; | |
1828 | ||
1829 | if (*imbalance < SCHED_LOAD_SCALE) { | |
1830 | unsigned long pwr_now = 0, pwr_move = 0; | |
1831 | unsigned long tmp; | |
1832 | ||
1833 | if (max_load - this_load >= SCHED_LOAD_SCALE*2) { | |
1834 | *imbalance = 1; | |
1835 | return busiest; | |
1836 | } | |
1837 | ||
1838 | /* | |
1839 | * OK, we don't have enough imbalance to justify moving tasks, | |
1840 | * however we may be able to increase total CPU power used by | |
1841 | * moving them. | |
1842 | */ | |
1843 | ||
1844 | pwr_now += busiest->cpu_power*min(SCHED_LOAD_SCALE, max_load); | |
1845 | pwr_now += this->cpu_power*min(SCHED_LOAD_SCALE, this_load); | |
1846 | pwr_now /= SCHED_LOAD_SCALE; | |
1847 | ||
1848 | /* Amount of load we'd subtract */ | |
1849 | tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/busiest->cpu_power; | |
1850 | if (max_load > tmp) | |
1851 | pwr_move += busiest->cpu_power*min(SCHED_LOAD_SCALE, | |
1852 | max_load - tmp); | |
1853 | ||
1854 | /* Amount of load we'd add */ | |
1855 | if (max_load*busiest->cpu_power < | |
1856 | SCHED_LOAD_SCALE*SCHED_LOAD_SCALE) | |
1857 | tmp = max_load*busiest->cpu_power/this->cpu_power; | |
1858 | else | |
1859 | tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power; | |
1860 | pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp); | |
1861 | pwr_move /= SCHED_LOAD_SCALE; | |
1862 | ||
1863 | /* Move if we gain throughput */ | |
1864 | if (pwr_move <= pwr_now) | |
1865 | goto out_balanced; | |
1866 | ||
1867 | *imbalance = 1; | |
1868 | return busiest; | |
1869 | } | |
1870 | ||
1871 | /* Get rid of the scaling factor, rounding down as we divide */ | |
1872 | *imbalance = *imbalance / SCHED_LOAD_SCALE; | |
1873 | ||
1874 | return busiest; | |
1875 | ||
1876 | out_balanced: | |
1877 | if (busiest && (idle == NEWLY_IDLE || | |
1878 | (idle == SCHED_IDLE && max_load > SCHED_LOAD_SCALE)) ) { | |
1879 | *imbalance = 1; | |
1880 | return busiest; | |
1881 | } | |
1882 | ||
1883 | *imbalance = 0; | |
1884 | return NULL; | |
1885 | } | |
1886 | ||
1887 | /* | |
1888 | * find_busiest_queue - find the busiest runqueue among the cpus in group. | |
1889 | */ | |
1890 | static runqueue_t *find_busiest_queue(struct sched_group *group) | |
1891 | { | |
1892 | unsigned long load, max_load = 0; | |
1893 | runqueue_t *busiest = NULL; | |
1894 | int i; | |
1895 | ||
1896 | for_each_cpu_mask(i, group->cpumask) { | |
1897 | load = source_load(i); | |
1898 | ||
1899 | if (load > max_load) { | |
1900 | max_load = load; | |
1901 | busiest = cpu_rq(i); | |
1902 | } | |
1903 | } | |
1904 | ||
1905 | return busiest; | |
1906 | } | |
1907 | ||
1908 | /* | |
1909 | * Check this_cpu to ensure it is balanced within domain. Attempt to move | |
1910 | * tasks if there is an imbalance. | |
1911 | * | |
1912 | * Called with this_rq unlocked. | |
1913 | */ | |
1914 | static int load_balance(int this_cpu, runqueue_t *this_rq, | |
1915 | struct sched_domain *sd, enum idle_type idle) | |
1916 | { | |
1917 | struct sched_group *group; | |
1918 | runqueue_t *busiest; | |
1919 | unsigned long imbalance; | |
1920 | int nr_moved; | |
1921 | ||
1922 | spin_lock(&this_rq->lock); | |
1923 | schedstat_inc(sd, lb_cnt[idle]); | |
1924 | ||
1925 | group = find_busiest_group(sd, this_cpu, &imbalance, idle); | |
1926 | if (!group) { | |
1927 | schedstat_inc(sd, lb_nobusyg[idle]); | |
1928 | goto out_balanced; | |
1929 | } | |
1930 | ||
1931 | busiest = find_busiest_queue(group); | |
1932 | if (!busiest) { | |
1933 | schedstat_inc(sd, lb_nobusyq[idle]); | |
1934 | goto out_balanced; | |
1935 | } | |
1936 | ||
1937 | /* | |
1938 | * This should be "impossible", but since load | |
1939 | * balancing is inherently racy and statistical, | |
1940 | * it could happen in theory. | |
1941 | */ | |
1942 | if (unlikely(busiest == this_rq)) { | |
1943 | WARN_ON(1); | |
1944 | goto out_balanced; | |
1945 | } | |
1946 | ||
1947 | schedstat_add(sd, lb_imbalance[idle], imbalance); | |
1948 | ||
1949 | nr_moved = 0; | |
1950 | if (busiest->nr_running > 1) { | |
1951 | /* | |
1952 | * Attempt to move tasks. If find_busiest_group has found | |
1953 | * an imbalance but busiest->nr_running <= 1, the group is | |
1954 | * still unbalanced. nr_moved simply stays zero, so it is | |
1955 | * correctly treated as an imbalance. | |
1956 | */ | |
1957 | double_lock_balance(this_rq, busiest); | |
1958 | nr_moved = move_tasks(this_rq, this_cpu, busiest, | |
1959 | imbalance, sd, idle); | |
1960 | spin_unlock(&busiest->lock); | |
1961 | } | |
1962 | spin_unlock(&this_rq->lock); | |
1963 | ||
1964 | if (!nr_moved) { | |
1965 | schedstat_inc(sd, lb_failed[idle]); | |
1966 | sd->nr_balance_failed++; | |
1967 | ||
1968 | if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) { | |
1969 | int wake = 0; | |
1970 | ||
1971 | spin_lock(&busiest->lock); | |
1972 | if (!busiest->active_balance) { | |
1973 | busiest->active_balance = 1; | |
1974 | busiest->push_cpu = this_cpu; | |
1975 | wake = 1; | |
1976 | } | |
1977 | spin_unlock(&busiest->lock); | |
1978 | if (wake) | |
1979 | wake_up_process(busiest->migration_thread); | |
1980 | ||
1981 | /* | |
1982 | * We've kicked active balancing, reset the failure | |
1983 | * counter. | |
1984 | */ | |
1985 | sd->nr_balance_failed = sd->cache_nice_tries; | |
1986 | } | |
1987 | ||
1988 | /* | |
1989 | * We were unbalanced, but unsuccessful in move_tasks(), | |
1990 | * so bump the balance_interval to lessen the lock contention. | |
1991 | */ | |
1992 | if (sd->balance_interval < sd->max_interval) | |
1993 | sd->balance_interval++; | |
1994 | } else { | |
1995 | sd->nr_balance_failed = 0; | |
1996 | ||
1997 | /* We were unbalanced, so reset the balancing interval */ | |
1998 | sd->balance_interval = sd->min_interval; | |
1999 | } | |
2000 | ||
2001 | return nr_moved; | |
2002 | ||
2003 | out_balanced: | |
2004 | spin_unlock(&this_rq->lock); | |
2005 | ||
2006 | schedstat_inc(sd, lb_balanced[idle]); | |
2007 | ||
2008 | /* tune up the balancing interval */ | |
2009 | if (sd->balance_interval < sd->max_interval) | |
2010 | sd->balance_interval *= 2; | |
2011 | ||
2012 | return 0; | |
2013 | } | |
2014 | ||
2015 | /* | |
2016 | * Check this_cpu to ensure it is balanced within domain. Attempt to move | |
2017 | * tasks if there is an imbalance. | |
2018 | * | |
2019 | * Called from schedule when this_rq is about to become idle (NEWLY_IDLE). | |
2020 | * this_rq is locked. | |
2021 | */ | |
2022 | static int load_balance_newidle(int this_cpu, runqueue_t *this_rq, | |
2023 | struct sched_domain *sd) | |
2024 | { | |
2025 | struct sched_group *group; | |
2026 | runqueue_t *busiest = NULL; | |
2027 | unsigned long imbalance; | |
2028 | int nr_moved = 0; | |
2029 | ||
2030 | schedstat_inc(sd, lb_cnt[NEWLY_IDLE]); | |
2031 | group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE); | |
2032 | if (!group) { | |
2033 | schedstat_inc(sd, lb_balanced[NEWLY_IDLE]); | |
2034 | schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]); | |
2035 | goto out; | |
2036 | } | |
2037 | ||
2038 | busiest = find_busiest_queue(group); | |
2039 | if (!busiest || busiest == this_rq) { | |
2040 | schedstat_inc(sd, lb_balanced[NEWLY_IDLE]); | |
2041 | schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]); | |
2042 | goto out; | |
2043 | } | |
2044 | ||
2045 | /* Attempt to move tasks */ | |
2046 | double_lock_balance(this_rq, busiest); | |
2047 | ||
2048 | schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance); | |
2049 | nr_moved = move_tasks(this_rq, this_cpu, busiest, | |
2050 | imbalance, sd, NEWLY_IDLE); | |
2051 | if (!nr_moved) | |
2052 | schedstat_inc(sd, lb_failed[NEWLY_IDLE]); | |
2053 | ||
2054 | spin_unlock(&busiest->lock); | |
2055 | ||
2056 | out: | |
2057 | return nr_moved; | |
2058 | } | |
2059 | ||
2060 | /* | |
2061 | * idle_balance is called by schedule() if this_cpu is about to become | |
2062 | * idle. Attempts to pull tasks from other CPUs. | |
2063 | */ | |
2064 | static inline void idle_balance(int this_cpu, runqueue_t *this_rq) | |
2065 | { | |
2066 | struct sched_domain *sd; | |
2067 | ||
2068 | for_each_domain(this_cpu, sd) { | |
2069 | if (sd->flags & SD_BALANCE_NEWIDLE) { | |
2070 | if (load_balance_newidle(this_cpu, this_rq, sd)) { | |
2071 | /* We've pulled tasks over so stop searching */ | |
2072 | break; | |
2073 | } | |
2074 | } | |
2075 | } | |
2076 | } | |
2077 | ||
2078 | /* | |
2079 | * active_load_balance is run by migration threads. It pushes running tasks | |
2080 | * off the busiest CPU onto idle CPUs. It requires at least 1 task to be | |
2081 | * running on each physical CPU where possible, and avoids physical / | |
2082 | * logical imbalances. | |
2083 | * | |
2084 | * Called with busiest_rq locked. | |
2085 | */ | |
2086 | static void active_load_balance(runqueue_t *busiest_rq, int busiest_cpu) | |
2087 | { | |
2088 | struct sched_domain *sd; | |
2089 | struct sched_group *cpu_group; | |
2090 | runqueue_t *target_rq; | |
2091 | cpumask_t visited_cpus; | |
2092 | int cpu; | |
2093 | ||
2094 | /* | |
2095 | * Search for suitable CPUs to push tasks to in successively higher | |
2096 | * domains with SD_LOAD_BALANCE set. | |
2097 | */ | |
2098 | visited_cpus = CPU_MASK_NONE; | |
2099 | for_each_domain(busiest_cpu, sd) { | |
2100 | if (!(sd->flags & SD_LOAD_BALANCE)) | |
2101 | /* no more domains to search */ | |
2102 | break; | |
2103 | ||
2104 | schedstat_inc(sd, alb_cnt); | |
2105 | ||
2106 | cpu_group = sd->groups; | |
2107 | do { | |
2108 | for_each_cpu_mask(cpu, cpu_group->cpumask) { | |
2109 | if (busiest_rq->nr_running <= 1) | |
2110 | /* no more tasks left to move */ | |
2111 | return; | |
2112 | if (cpu_isset(cpu, visited_cpus)) | |
2113 | continue; | |
2114 | cpu_set(cpu, visited_cpus); | |
2115 | if (!cpu_and_siblings_are_idle(cpu) || cpu == busiest_cpu) | |
2116 | continue; | |
2117 | ||
2118 | target_rq = cpu_rq(cpu); | |
2119 | /* | |
2120 | * This condition is "impossible", if it occurs | |
2121 | * we need to fix it. Originally reported by | |
2122 | * Bjorn Helgaas on a 128-cpu setup. | |
2123 | */ | |
2124 | BUG_ON(busiest_rq == target_rq); | |
2125 | ||
2126 | /* move a task from busiest_rq to target_rq */ | |
2127 | double_lock_balance(busiest_rq, target_rq); | |
2128 | if (move_tasks(target_rq, cpu, busiest_rq, | |
2129 | 1, sd, SCHED_IDLE)) { | |
2130 | schedstat_inc(sd, alb_pushed); | |
2131 | } else { | |
2132 | schedstat_inc(sd, alb_failed); | |
2133 | } | |
2134 | spin_unlock(&target_rq->lock); | |
2135 | } | |
2136 | cpu_group = cpu_group->next; | |
2137 | } while (cpu_group != sd->groups); | |
2138 | } | |
2139 | } | |
2140 | ||
2141 | /* | |
2142 | * rebalance_tick will get called every timer tick, on every CPU. | |
2143 | * | |
2144 | * It checks each scheduling domain to see if it is due to be balanced, | |
2145 | * and initiates a balancing operation if so. | |
2146 | * | |
2147 | * Balancing parameters are set up in arch_init_sched_domains. | |
2148 | */ | |
2149 | ||
2150 | /* Don't have all balancing operations going off at once */ | |
2151 | #define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS) | |
2152 | ||
2153 | static void rebalance_tick(int this_cpu, runqueue_t *this_rq, | |
2154 | enum idle_type idle) | |
2155 | { | |
2156 | unsigned long old_load, this_load; | |
2157 | unsigned long j = jiffies + CPU_OFFSET(this_cpu); | |
2158 | struct sched_domain *sd; | |
2159 | ||
2160 | /* Update our load */ | |
2161 | old_load = this_rq->cpu_load; | |
2162 | this_load = this_rq->nr_running * SCHED_LOAD_SCALE; | |
2163 | /* | |
2164 | * Round up the averaging division if load is increasing. This | |
2165 | * prevents us from getting stuck on 9 if the load is 10, for | |
2166 | * example. | |
2167 | */ | |
2168 | if (this_load > old_load) | |
2169 | old_load++; | |
2170 | this_rq->cpu_load = (old_load + this_load) / 2; | |
2171 | ||
2172 | for_each_domain(this_cpu, sd) { | |
2173 | unsigned long interval; | |
2174 | ||
2175 | if (!(sd->flags & SD_LOAD_BALANCE)) | |
2176 | continue; | |
2177 | ||
2178 | interval = sd->balance_interval; | |
2179 | if (idle != SCHED_IDLE) | |
2180 | interval *= sd->busy_factor; | |
2181 | ||
2182 | /* scale ms to jiffies */ | |
2183 | interval = msecs_to_jiffies(interval); | |
2184 | if (unlikely(!interval)) | |
2185 | interval = 1; | |
2186 | ||
2187 | if (j - sd->last_balance >= interval) { | |
2188 | if (load_balance(this_cpu, this_rq, sd, idle)) { | |
2189 | /* We've pulled tasks over so no longer idle */ | |
2190 | idle = NOT_IDLE; | |
2191 | } | |
2192 | sd->last_balance += interval; | |
2193 | } | |
2194 | } | |
2195 | } | |
2196 | #else | |
2197 | /* | |
2198 | * on UP we do not need to balance between CPUs: | |
2199 | */ | |
2200 | static inline void rebalance_tick(int cpu, runqueue_t *rq, enum idle_type idle) | |
2201 | { | |
2202 | } | |
2203 | static inline void idle_balance(int cpu, runqueue_t *rq) | |
2204 | { | |
2205 | } | |
2206 | #endif | |
2207 | ||
2208 | static inline int wake_priority_sleeper(runqueue_t *rq) | |
2209 | { | |
2210 | int ret = 0; | |
2211 | #ifdef CONFIG_SCHED_SMT | |
2212 | spin_lock(&rq->lock); | |
2213 | /* | |
2214 | * If an SMT sibling task has been put to sleep for priority | |
2215 | * reasons reschedule the idle task to see if it can now run. | |
2216 | */ | |
2217 | if (rq->nr_running) { | |
2218 | resched_task(rq->idle); | |
2219 | ret = 1; | |
2220 | } | |
2221 | spin_unlock(&rq->lock); | |
2222 | #endif | |
2223 | return ret; | |
2224 | } | |
2225 | ||
2226 | DEFINE_PER_CPU(struct kernel_stat, kstat); | |
2227 | ||
2228 | EXPORT_PER_CPU_SYMBOL(kstat); | |
2229 | ||
2230 | /* | |
2231 | * This is called on clock ticks and on context switches. | |
2232 | * Bank in p->sched_time the ns elapsed since the last tick or switch. | |
2233 | */ | |
2234 | static inline void update_cpu_clock(task_t *p, runqueue_t *rq, | |
2235 | unsigned long long now) | |
2236 | { | |
2237 | unsigned long long last = max(p->timestamp, rq->timestamp_last_tick); | |
2238 | p->sched_time += now - last; | |
2239 | } | |
2240 | ||
2241 | /* | |
2242 | * Return current->sched_time plus any more ns on the sched_clock | |
2243 | * that have not yet been banked. | |
2244 | */ | |
2245 | unsigned long long current_sched_time(const task_t *tsk) | |
2246 | { | |
2247 | unsigned long long ns; | |
2248 | unsigned long flags; | |
2249 | local_irq_save(flags); | |
2250 | ns = max(tsk->timestamp, task_rq(tsk)->timestamp_last_tick); | |
2251 | ns = tsk->sched_time + (sched_clock() - ns); | |
2252 | local_irq_restore(flags); | |
2253 | return ns; | |
2254 | } | |
2255 | ||
2256 | /* | |
2257 | * We place interactive tasks back into the active array, if possible. | |
2258 | * | |
2259 | * To guarantee that this does not starve expired tasks we ignore the | |
2260 | * interactivity of a task if the first expired task had to wait more | |
2261 | * than a 'reasonable' amount of time. This deadline timeout is | |
2262 | * load-dependent, as the frequency of array switched decreases with | |
2263 | * increasing number of running tasks. We also ignore the interactivity | |
2264 | * if a better static_prio task has expired: | |
2265 | */ | |
2266 | #define EXPIRED_STARVING(rq) \ | |
2267 | ((STARVATION_LIMIT && ((rq)->expired_timestamp && \ | |
2268 | (jiffies - (rq)->expired_timestamp >= \ | |
2269 | STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \ | |
2270 | ((rq)->curr->static_prio > (rq)->best_expired_prio)) | |
2271 | ||
2272 | /* | |
2273 | * Account user cpu time to a process. | |
2274 | * @p: the process that the cpu time gets accounted to | |
2275 | * @hardirq_offset: the offset to subtract from hardirq_count() | |
2276 | * @cputime: the cpu time spent in user space since the last update | |
2277 | */ | |
2278 | void account_user_time(struct task_struct *p, cputime_t cputime) | |
2279 | { | |
2280 | struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; | |
2281 | cputime64_t tmp; | |
2282 | ||
2283 | p->utime = cputime_add(p->utime, cputime); | |
2284 | ||
2285 | /* Add user time to cpustat. */ | |
2286 | tmp = cputime_to_cputime64(cputime); | |
2287 | if (TASK_NICE(p) > 0) | |
2288 | cpustat->nice = cputime64_add(cpustat->nice, tmp); | |
2289 | else | |
2290 | cpustat->user = cputime64_add(cpustat->user, tmp); | |
2291 | } | |
2292 | ||
2293 | /* | |
2294 | * Account system cpu time to a process. | |
2295 | * @p: the process that the cpu time gets accounted to | |
2296 | * @hardirq_offset: the offset to subtract from hardirq_count() | |
2297 | * @cputime: the cpu time spent in kernel space since the last update | |
2298 | */ | |
2299 | void account_system_time(struct task_struct *p, int hardirq_offset, | |
2300 | cputime_t cputime) | |
2301 | { | |
2302 | struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; | |
2303 | runqueue_t *rq = this_rq(); | |
2304 | cputime64_t tmp; | |
2305 | ||
2306 | p->stime = cputime_add(p->stime, cputime); | |
2307 | ||
2308 | /* Add system time to cpustat. */ | |
2309 | tmp = cputime_to_cputime64(cputime); | |
2310 | if (hardirq_count() - hardirq_offset) | |
2311 | cpustat->irq = cputime64_add(cpustat->irq, tmp); | |
2312 | else if (softirq_count()) | |
2313 | cpustat->softirq = cputime64_add(cpustat->softirq, tmp); | |
2314 | else if (p != rq->idle) | |
2315 | cpustat->system = cputime64_add(cpustat->system, tmp); | |
2316 | else if (atomic_read(&rq->nr_iowait) > 0) | |
2317 | cpustat->iowait = cputime64_add(cpustat->iowait, tmp); | |
2318 | else | |
2319 | cpustat->idle = cputime64_add(cpustat->idle, tmp); | |
2320 | /* Account for system time used */ | |
2321 | acct_update_integrals(p); | |
2322 | /* Update rss highwater mark */ | |
2323 | update_mem_hiwater(p); | |
2324 | } | |
2325 | ||
2326 | /* | |
2327 | * Account for involuntary wait time. | |
2328 | * @p: the process from which the cpu time has been stolen | |
2329 | * @steal: the cpu time spent in involuntary wait | |
2330 | */ | |
2331 | void account_steal_time(struct task_struct *p, cputime_t steal) | |
2332 | { | |
2333 | struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; | |
2334 | cputime64_t tmp = cputime_to_cputime64(steal); | |
2335 | runqueue_t *rq = this_rq(); | |
2336 | ||
2337 | if (p == rq->idle) { | |
2338 | p->stime = cputime_add(p->stime, steal); | |
2339 | if (atomic_read(&rq->nr_iowait) > 0) | |
2340 | cpustat->iowait = cputime64_add(cpustat->iowait, tmp); | |
2341 | else | |
2342 | cpustat->idle = cputime64_add(cpustat->idle, tmp); | |
2343 | } else | |
2344 | cpustat->steal = cputime64_add(cpustat->steal, tmp); | |
2345 | } | |
2346 | ||
2347 | /* | |
2348 | * This function gets called by the timer code, with HZ frequency. | |
2349 | * We call it with interrupts disabled. | |
2350 | * | |
2351 | * It also gets called by the fork code, when changing the parent's | |
2352 | * timeslices. | |
2353 | */ | |
2354 | void scheduler_tick(void) | |
2355 | { | |
2356 | int cpu = smp_processor_id(); | |
2357 | runqueue_t *rq = this_rq(); | |
2358 | task_t *p = current; | |
2359 | unsigned long long now = sched_clock(); | |
2360 | ||
2361 | update_cpu_clock(p, rq, now); | |
2362 | ||
2363 | rq->timestamp_last_tick = now; | |
2364 | ||
2365 | if (p == rq->idle) { | |
2366 | if (wake_priority_sleeper(rq)) | |
2367 | goto out; | |
2368 | rebalance_tick(cpu, rq, SCHED_IDLE); | |
2369 | return; | |
2370 | } | |
2371 | ||
2372 | /* Task might have expired already, but not scheduled off yet */ | |
2373 | if (p->array != rq->active) { | |
2374 | set_tsk_need_resched(p); | |
2375 | goto out; | |
2376 | } | |
2377 | spin_lock(&rq->lock); | |
2378 | /* | |
2379 | * The task was running during this tick - update the | |
2380 | * time slice counter. Note: we do not update a thread's | |
2381 | * priority until it either goes to sleep or uses up its | |
2382 | * timeslice. This makes it possible for interactive tasks | |
2383 | * to use up their timeslices at their highest priority levels. | |
2384 | */ | |
2385 | if (rt_task(p)) { | |
2386 | /* | |
2387 | * RR tasks need a special form of timeslice management. | |
2388 | * FIFO tasks have no timeslices. | |
2389 | */ | |
2390 | if ((p->policy == SCHED_RR) && !--p->time_slice) { | |
2391 | p->time_slice = task_timeslice(p); | |
2392 | p->first_time_slice = 0; | |
2393 | set_tsk_need_resched(p); | |
2394 | ||
2395 | /* put it at the end of the queue: */ | |
2396 | requeue_task(p, rq->active); | |
2397 | } | |
2398 | goto out_unlock; | |
2399 | } | |
2400 | if (!--p->time_slice) { | |
2401 | dequeue_task(p, rq->active); | |
2402 | set_tsk_need_resched(p); | |
2403 | p->prio = effective_prio(p); | |
2404 | p->time_slice = task_timeslice(p); | |
2405 | p->first_time_slice = 0; | |
2406 | ||
2407 | if (!rq->expired_timestamp) | |
2408 | rq->expired_timestamp = jiffies; | |
2409 | if (!TASK_INTERACTIVE(p) || EXPIRED_STARVING(rq)) { | |
2410 | enqueue_task(p, rq->expired); | |
2411 | if (p->static_prio < rq->best_expired_prio) | |
2412 | rq->best_expired_prio = p->static_prio; | |
2413 | } else | |
2414 | enqueue_task(p, rq->active); | |
2415 | } else { | |
2416 | /* | |
2417 | * Prevent a too long timeslice allowing a task to monopolize | |
2418 | * the CPU. We do this by splitting up the timeslice into | |
2419 | * smaller pieces. | |
2420 | * | |
2421 | * Note: this does not mean the task's timeslices expire or | |
2422 | * get lost in any way, they just might be preempted by | |
2423 | * another task of equal priority. (one with higher | |
2424 | * priority would have preempted this task already.) We | |
2425 | * requeue this task to the end of the list on this priority | |
2426 | * level, which is in essence a round-robin of tasks with | |
2427 | * equal priority. | |
2428 | * | |
2429 | * This only applies to tasks in the interactive | |
2430 | * delta range with at least TIMESLICE_GRANULARITY to requeue. | |
2431 | */ | |
2432 | if (TASK_INTERACTIVE(p) && !((task_timeslice(p) - | |
2433 | p->time_slice) % TIMESLICE_GRANULARITY(p)) && | |
2434 | (p->time_slice >= TIMESLICE_GRANULARITY(p)) && | |
2435 | (p->array == rq->active)) { | |
2436 | ||
2437 | requeue_task(p, rq->active); | |
2438 | set_tsk_need_resched(p); | |
2439 | } | |
2440 | } | |
2441 | out_unlock: | |
2442 | spin_unlock(&rq->lock); | |
2443 | out: | |
2444 | rebalance_tick(cpu, rq, NOT_IDLE); | |
2445 | } | |
2446 | ||
2447 | #ifdef CONFIG_SCHED_SMT | |
2448 | static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq) | |
2449 | { | |
2450 | struct sched_domain *sd = this_rq->sd; | |
2451 | cpumask_t sibling_map; | |
2452 | int i; | |
2453 | ||
2454 | if (!(sd->flags & SD_SHARE_CPUPOWER)) | |
2455 | return; | |
2456 | ||
2457 | /* | |
2458 | * Unlock the current runqueue because we have to lock in | |
2459 | * CPU order to avoid deadlocks. Caller knows that we might | |
2460 | * unlock. We keep IRQs disabled. | |
2461 | */ | |
2462 | spin_unlock(&this_rq->lock); | |
2463 | ||
2464 | sibling_map = sd->span; | |
2465 | ||
2466 | for_each_cpu_mask(i, sibling_map) | |
2467 | spin_lock(&cpu_rq(i)->lock); | |
2468 | /* | |
2469 | * We clear this CPU from the mask. This both simplifies the | |
2470 | * inner loop and keps this_rq locked when we exit: | |
2471 | */ | |
2472 | cpu_clear(this_cpu, sibling_map); | |
2473 | ||
2474 | for_each_cpu_mask(i, sibling_map) { | |
2475 | runqueue_t *smt_rq = cpu_rq(i); | |
2476 | ||
2477 | /* | |
2478 | * If an SMT sibling task is sleeping due to priority | |
2479 | * reasons wake it up now. | |
2480 | */ | |
2481 | if (smt_rq->curr == smt_rq->idle && smt_rq->nr_running) | |
2482 | resched_task(smt_rq->idle); | |
2483 | } | |
2484 | ||
2485 | for_each_cpu_mask(i, sibling_map) | |
2486 | spin_unlock(&cpu_rq(i)->lock); | |
2487 | /* | |
2488 | * We exit with this_cpu's rq still held and IRQs | |
2489 | * still disabled: | |
2490 | */ | |
2491 | } | |
2492 | ||
2493 | static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq) | |
2494 | { | |
2495 | struct sched_domain *sd = this_rq->sd; | |
2496 | cpumask_t sibling_map; | |
2497 | prio_array_t *array; | |
2498 | int ret = 0, i; | |
2499 | task_t *p; | |
2500 | ||
2501 | if (!(sd->flags & SD_SHARE_CPUPOWER)) | |
2502 | return 0; | |
2503 | ||
2504 | /* | |
2505 | * The same locking rules and details apply as for | |
2506 | * wake_sleeping_dependent(): | |
2507 | */ | |
2508 | spin_unlock(&this_rq->lock); | |
2509 | sibling_map = sd->span; | |
2510 | for_each_cpu_mask(i, sibling_map) | |
2511 | spin_lock(&cpu_rq(i)->lock); | |
2512 | cpu_clear(this_cpu, sibling_map); | |
2513 | ||
2514 | /* | |
2515 | * Establish next task to be run - it might have gone away because | |
2516 | * we released the runqueue lock above: | |
2517 | */ | |
2518 | if (!this_rq->nr_running) | |
2519 | goto out_unlock; | |
2520 | array = this_rq->active; | |
2521 | if (!array->nr_active) | |
2522 | array = this_rq->expired; | |
2523 | BUG_ON(!array->nr_active); | |
2524 | ||
2525 | p = list_entry(array->queue[sched_find_first_bit(array->bitmap)].next, | |
2526 | task_t, run_list); | |
2527 | ||
2528 | for_each_cpu_mask(i, sibling_map) { | |
2529 | runqueue_t *smt_rq = cpu_rq(i); | |
2530 | task_t *smt_curr = smt_rq->curr; | |
2531 | ||
2532 | /* | |
2533 | * If a user task with lower static priority than the | |
2534 | * running task on the SMT sibling is trying to schedule, | |
2535 | * delay it till there is proportionately less timeslice | |
2536 | * left of the sibling task to prevent a lower priority | |
2537 | * task from using an unfair proportion of the | |
2538 | * physical cpu's resources. -ck | |
2539 | */ | |
2540 | if (((smt_curr->time_slice * (100 - sd->per_cpu_gain) / 100) > | |
2541 | task_timeslice(p) || rt_task(smt_curr)) && | |
2542 | p->mm && smt_curr->mm && !rt_task(p)) | |
2543 | ret = 1; | |
2544 | ||
2545 | /* | |
2546 | * Reschedule a lower priority task on the SMT sibling, | |
2547 | * or wake it up if it has been put to sleep for priority | |
2548 | * reasons. | |
2549 | */ | |
2550 | if ((((p->time_slice * (100 - sd->per_cpu_gain) / 100) > | |
2551 | task_timeslice(smt_curr) || rt_task(p)) && | |
2552 | smt_curr->mm && p->mm && !rt_task(smt_curr)) || | |
2553 | (smt_curr == smt_rq->idle && smt_rq->nr_running)) | |
2554 | resched_task(smt_curr); | |
2555 | } | |
2556 | out_unlock: | |
2557 | for_each_cpu_mask(i, sibling_map) | |
2558 | spin_unlock(&cpu_rq(i)->lock); | |
2559 | return ret; | |
2560 | } | |
2561 | #else | |
2562 | static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq) | |
2563 | { | |
2564 | } | |
2565 | ||
2566 | static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq) | |
2567 | { | |
2568 | return 0; | |
2569 | } | |
2570 | #endif | |
2571 | ||
2572 | #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT) | |
2573 | ||
2574 | void fastcall add_preempt_count(int val) | |
2575 | { | |
2576 | /* | |
2577 | * Underflow? | |
2578 | */ | |
2579 | BUG_ON(((int)preempt_count() < 0)); | |
2580 | preempt_count() += val; | |
2581 | /* | |
2582 | * Spinlock count overflowing soon? | |
2583 | */ | |
2584 | BUG_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK-10); | |
2585 | } | |
2586 | EXPORT_SYMBOL(add_preempt_count); | |
2587 | ||
2588 | void fastcall sub_preempt_count(int val) | |
2589 | { | |
2590 | /* | |
2591 | * Underflow? | |
2592 | */ | |
2593 | BUG_ON(val > preempt_count()); | |
2594 | /* | |
2595 | * Is the spinlock portion underflowing? | |
2596 | */ | |
2597 | BUG_ON((val < PREEMPT_MASK) && !(preempt_count() & PREEMPT_MASK)); | |
2598 | preempt_count() -= val; | |
2599 | } | |
2600 | EXPORT_SYMBOL(sub_preempt_count); | |
2601 | ||
2602 | #endif | |
2603 | ||
2604 | /* | |
2605 | * schedule() is the main scheduler function. | |
2606 | */ | |
2607 | asmlinkage void __sched schedule(void) | |
2608 | { | |
2609 | long *switch_count; | |
2610 | task_t *prev, *next; | |
2611 | runqueue_t *rq; | |
2612 | prio_array_t *array; | |
2613 | struct list_head *queue; | |
2614 | unsigned long long now; | |
2615 | unsigned long run_time; | |
2616 | int cpu, idx; | |
2617 | ||
2618 | /* | |
2619 | * Test if we are atomic. Since do_exit() needs to call into | |
2620 | * schedule() atomically, we ignore that path for now. | |
2621 | * Otherwise, whine if we are scheduling when we should not be. | |
2622 | */ | |
2623 | if (likely(!current->exit_state)) { | |
2624 | if (unlikely(in_atomic())) { | |
2625 | printk(KERN_ERR "scheduling while atomic: " | |
2626 | "%s/0x%08x/%d\n", | |
2627 | current->comm, preempt_count(), current->pid); | |
2628 | dump_stack(); | |
2629 | } | |
2630 | } | |
2631 | profile_hit(SCHED_PROFILING, __builtin_return_address(0)); | |
2632 | ||
2633 | need_resched: | |
2634 | preempt_disable(); | |
2635 | prev = current; | |
2636 | release_kernel_lock(prev); | |
2637 | need_resched_nonpreemptible: | |
2638 | rq = this_rq(); | |
2639 | ||
2640 | /* | |
2641 | * The idle thread is not allowed to schedule! | |
2642 | * Remove this check after it has been exercised a bit. | |
2643 | */ | |
2644 | if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) { | |
2645 | printk(KERN_ERR "bad: scheduling from the idle thread!\n"); | |
2646 | dump_stack(); | |
2647 | } | |
2648 | ||
2649 | schedstat_inc(rq, sched_cnt); | |
2650 | now = sched_clock(); | |
2651 | if (likely((long long)now - prev->timestamp < NS_MAX_SLEEP_AVG)) { | |
2652 | run_time = now - prev->timestamp; | |
2653 | if (unlikely((long long)now - prev->timestamp < 0)) | |
2654 | run_time = 0; | |
2655 | } else | |
2656 | run_time = NS_MAX_SLEEP_AVG; | |
2657 | ||
2658 | /* | |
2659 | * Tasks charged proportionately less run_time at high sleep_avg to | |
2660 | * delay them losing their interactive status | |
2661 | */ | |
2662 | run_time /= (CURRENT_BONUS(prev) ? : 1); | |
2663 | ||
2664 | spin_lock_irq(&rq->lock); | |
2665 | ||
2666 | if (unlikely(prev->flags & PF_DEAD)) | |
2667 | prev->state = EXIT_DEAD; | |
2668 | ||
2669 | switch_count = &prev->nivcsw; | |
2670 | if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { | |
2671 | switch_count = &prev->nvcsw; | |
2672 | if (unlikely((prev->state & TASK_INTERRUPTIBLE) && | |
2673 | unlikely(signal_pending(prev)))) | |
2674 | prev->state = TASK_RUNNING; | |
2675 | else { | |
2676 | if (prev->state == TASK_UNINTERRUPTIBLE) | |
2677 | rq->nr_uninterruptible++; | |
2678 | deactivate_task(prev, rq); | |
2679 | } | |
2680 | } | |
2681 | ||
2682 | cpu = smp_processor_id(); | |
2683 | if (unlikely(!rq->nr_running)) { | |
2684 | go_idle: | |
2685 | idle_balance(cpu, rq); | |
2686 | if (!rq->nr_running) { | |
2687 | next = rq->idle; | |
2688 | rq->expired_timestamp = 0; | |
2689 | wake_sleeping_dependent(cpu, rq); | |
2690 | /* | |
2691 | * wake_sleeping_dependent() might have released | |
2692 | * the runqueue, so break out if we got new | |
2693 | * tasks meanwhile: | |
2694 | */ | |
2695 | if (!rq->nr_running) | |
2696 | goto switch_tasks; | |
2697 | } | |
2698 | } else { | |
2699 | if (dependent_sleeper(cpu, rq)) { | |
2700 | next = rq->idle; | |
2701 | goto switch_tasks; | |
2702 | } | |
2703 | /* | |
2704 | * dependent_sleeper() releases and reacquires the runqueue | |
2705 | * lock, hence go into the idle loop if the rq went | |
2706 | * empty meanwhile: | |
2707 | */ | |
2708 | if (unlikely(!rq->nr_running)) | |
2709 | goto go_idle; | |
2710 | } | |
2711 | ||
2712 | array = rq->active; | |
2713 | if (unlikely(!array->nr_active)) { | |
2714 | /* | |
2715 | * Switch the active and expired arrays. | |
2716 | */ | |
2717 | schedstat_inc(rq, sched_switch); | |
2718 | rq->active = rq->expired; | |
2719 | rq->expired = array; | |
2720 | array = rq->active; | |
2721 | rq->expired_timestamp = 0; | |
2722 | rq->best_expired_prio = MAX_PRIO; | |
2723 | } | |
2724 | ||
2725 | idx = sched_find_first_bit(array->bitmap); | |
2726 | queue = array->queue + idx; | |
2727 | next = list_entry(queue->next, task_t, run_list); | |
2728 | ||
2729 | if (!rt_task(next) && next->activated > 0) { | |
2730 | unsigned long long delta = now - next->timestamp; | |
2731 | if (unlikely((long long)now - next->timestamp < 0)) | |
2732 | delta = 0; | |
2733 | ||
2734 | if (next->activated == 1) | |
2735 | delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128; | |
2736 | ||
2737 | array = next->array; | |
2738 | dequeue_task(next, array); | |
2739 | recalc_task_prio(next, next->timestamp + delta); | |
2740 | enqueue_task(next, array); | |
2741 | } | |
2742 | next->activated = 0; | |
2743 | switch_tasks: | |
2744 | if (next == rq->idle) | |
2745 | schedstat_inc(rq, sched_goidle); | |
2746 | prefetch(next); | |
2747 | clear_tsk_need_resched(prev); | |
2748 | rcu_qsctr_inc(task_cpu(prev)); | |
2749 | ||
2750 | update_cpu_clock(prev, rq, now); | |
2751 | ||
2752 | prev->sleep_avg -= run_time; | |
2753 | if ((long)prev->sleep_avg <= 0) | |
2754 | prev->sleep_avg = 0; | |
2755 | prev->timestamp = prev->last_ran = now; | |
2756 | ||
2757 | sched_info_switch(prev, next); | |
2758 | if (likely(prev != next)) { | |
2759 | next->timestamp = now; | |
2760 | rq->nr_switches++; | |
2761 | rq->curr = next; | |
2762 | ++*switch_count; | |
2763 | ||
2764 | prepare_arch_switch(rq, next); | |
2765 | prev = context_switch(rq, prev, next); | |
2766 | barrier(); | |
2767 | ||
2768 | finish_task_switch(prev); | |
2769 | } else | |
2770 | spin_unlock_irq(&rq->lock); | |
2771 | ||
2772 | prev = current; | |
2773 | if (unlikely(reacquire_kernel_lock(prev) < 0)) | |
2774 | goto need_resched_nonpreemptible; | |
2775 | preempt_enable_no_resched(); | |
2776 | if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) | |
2777 | goto need_resched; | |
2778 | } | |
2779 | ||
2780 | EXPORT_SYMBOL(schedule); | |
2781 | ||
2782 | #ifdef CONFIG_PREEMPT | |
2783 | /* | |
2784 | * this is is the entry point to schedule() from in-kernel preemption | |
2785 | * off of preempt_enable. Kernel preemptions off return from interrupt | |
2786 | * occur there and call schedule directly. | |
2787 | */ | |
2788 | asmlinkage void __sched preempt_schedule(void) | |
2789 | { | |
2790 | struct thread_info *ti = current_thread_info(); | |
2791 | #ifdef CONFIG_PREEMPT_BKL | |
2792 | struct task_struct *task = current; | |
2793 | int saved_lock_depth; | |
2794 | #endif | |
2795 | /* | |
2796 | * If there is a non-zero preempt_count or interrupts are disabled, | |
2797 | * we do not want to preempt the current task. Just return.. | |
2798 | */ | |
2799 | if (unlikely(ti->preempt_count || irqs_disabled())) | |
2800 | return; | |
2801 | ||
2802 | need_resched: | |
2803 | add_preempt_count(PREEMPT_ACTIVE); | |
2804 | /* | |
2805 | * We keep the big kernel semaphore locked, but we | |
2806 | * clear ->lock_depth so that schedule() doesnt | |
2807 | * auto-release the semaphore: | |
2808 | */ | |
2809 | #ifdef CONFIG_PREEMPT_BKL | |
2810 | saved_lock_depth = task->lock_depth; | |
2811 | task->lock_depth = -1; | |
2812 | #endif | |
2813 | schedule(); | |
2814 | #ifdef CONFIG_PREEMPT_BKL | |
2815 | task->lock_depth = saved_lock_depth; | |
2816 | #endif | |
2817 | sub_preempt_count(PREEMPT_ACTIVE); | |
2818 | ||
2819 | /* we could miss a preemption opportunity between schedule and now */ | |
2820 | barrier(); | |
2821 | if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) | |
2822 | goto need_resched; | |
2823 | } | |
2824 | ||
2825 | EXPORT_SYMBOL(preempt_schedule); | |
2826 | ||
2827 | /* | |
2828 | * this is is the entry point to schedule() from kernel preemption | |
2829 | * off of irq context. | |
2830 | * Note, that this is called and return with irqs disabled. This will | |
2831 | * protect us against recursive calling from irq. | |
2832 | */ | |
2833 | asmlinkage void __sched preempt_schedule_irq(void) | |
2834 | { | |
2835 | struct thread_info *ti = current_thread_info(); | |
2836 | #ifdef CONFIG_PREEMPT_BKL | |
2837 | struct task_struct *task = current; | |
2838 | int saved_lock_depth; | |
2839 | #endif | |
2840 | /* Catch callers which need to be fixed*/ | |
2841 | BUG_ON(ti->preempt_count || !irqs_disabled()); | |
2842 | ||
2843 | need_resched: | |
2844 | add_preempt_count(PREEMPT_ACTIVE); | |
2845 | /* | |
2846 | * We keep the big kernel semaphore locked, but we | |
2847 | * clear ->lock_depth so that schedule() doesnt | |
2848 | * auto-release the semaphore: | |
2849 | */ | |
2850 | #ifdef CONFIG_PREEMPT_BKL | |
2851 | saved_lock_depth = task->lock_depth; | |
2852 | task->lock_depth = -1; | |
2853 | #endif | |
2854 | local_irq_enable(); | |
2855 | schedule(); | |
2856 | local_irq_disable(); | |
2857 | #ifdef CONFIG_PREEMPT_BKL | |
2858 | task->lock_depth = saved_lock_depth; | |
2859 | #endif | |
2860 | sub_preempt_count(PREEMPT_ACTIVE); | |
2861 | ||
2862 | /* we could miss a preemption opportunity between schedule and now */ | |
2863 | barrier(); | |
2864 | if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) | |
2865 | goto need_resched; | |
2866 | } | |
2867 | ||
2868 | #endif /* CONFIG_PREEMPT */ | |
2869 | ||
2870 | int default_wake_function(wait_queue_t *curr, unsigned mode, int sync, void *key) | |
2871 | { | |
2872 | task_t *p = curr->task; | |
2873 | return try_to_wake_up(p, mode, sync); | |
2874 | } | |
2875 | ||
2876 | EXPORT_SYMBOL(default_wake_function); | |
2877 | ||
2878 | /* | |
2879 | * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just | |
2880 | * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve | |
2881 | * number) then we wake all the non-exclusive tasks and one exclusive task. | |
2882 | * | |
2883 | * There are circumstances in which we can try to wake a task which has already | |
2884 | * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns | |
2885 | * zero in this (rare) case, and we handle it by continuing to scan the queue. | |
2886 | */ | |
2887 | static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, | |
2888 | int nr_exclusive, int sync, void *key) | |
2889 | { | |
2890 | struct list_head *tmp, *next; | |
2891 | ||
2892 | list_for_each_safe(tmp, next, &q->task_list) { | |
2893 | wait_queue_t *curr; | |
2894 | unsigned flags; | |
2895 | curr = list_entry(tmp, wait_queue_t, task_list); | |
2896 | flags = curr->flags; | |
2897 | if (curr->func(curr, mode, sync, key) && | |
2898 | (flags & WQ_FLAG_EXCLUSIVE) && | |
2899 | !--nr_exclusive) | |
2900 | break; | |
2901 | } | |
2902 | } | |
2903 | ||
2904 | /** | |
2905 | * __wake_up - wake up threads blocked on a waitqueue. | |
2906 | * @q: the waitqueue | |
2907 | * @mode: which threads | |
2908 | * @nr_exclusive: how many wake-one or wake-many threads to wake up | |
2909 | */ | |
2910 | void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode, | |
2911 | int nr_exclusive, void *key) | |
2912 | { | |
2913 | unsigned long flags; | |
2914 | ||
2915 | spin_lock_irqsave(&q->lock, flags); | |
2916 | __wake_up_common(q, mode, nr_exclusive, 0, key); | |
2917 | spin_unlock_irqrestore(&q->lock, flags); | |
2918 | } | |
2919 | ||
2920 | EXPORT_SYMBOL(__wake_up); | |
2921 | ||
2922 | /* | |
2923 | * Same as __wake_up but called with the spinlock in wait_queue_head_t held. | |
2924 | */ | |
2925 | void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode) | |
2926 | { | |
2927 | __wake_up_common(q, mode, 1, 0, NULL); | |
2928 | } | |
2929 | ||
2930 | /** | |
2931 | * __wake_up - sync- wake up threads blocked on a waitqueue. | |
2932 | * @q: the waitqueue | |
2933 | * @mode: which threads | |
2934 | * @nr_exclusive: how many wake-one or wake-many threads to wake up | |
2935 | * | |
2936 | * The sync wakeup differs that the waker knows that it will schedule | |
2937 | * away soon, so while the target thread will be woken up, it will not | |
2938 | * be migrated to another CPU - ie. the two threads are 'synchronized' | |
2939 | * with each other. This can prevent needless bouncing between CPUs. | |
2940 | * | |
2941 | * On UP it can prevent extra preemption. | |
2942 | */ | |
2943 | void fastcall __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive) | |
2944 | { | |
2945 | unsigned long flags; | |
2946 | int sync = 1; | |
2947 | ||
2948 | if (unlikely(!q)) | |
2949 | return; | |
2950 | ||
2951 | if (unlikely(!nr_exclusive)) | |
2952 | sync = 0; | |
2953 | ||
2954 | spin_lock_irqsave(&q->lock, flags); | |
2955 | __wake_up_common(q, mode, nr_exclusive, sync, NULL); | |
2956 | spin_unlock_irqrestore(&q->lock, flags); | |
2957 | } | |
2958 | EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */ | |
2959 | ||
2960 | void fastcall complete(struct completion *x) | |
2961 | { | |
2962 | unsigned long flags; | |
2963 | ||
2964 | spin_lock_irqsave(&x->wait.lock, flags); | |
2965 | x->done++; | |
2966 | __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, | |
2967 | 1, 0, NULL); | |
2968 | spin_unlock_irqrestore(&x->wait.lock, flags); | |
2969 | } | |
2970 | EXPORT_SYMBOL(complete); | |
2971 | ||
2972 | void fastcall complete_all(struct completion *x) | |
2973 | { | |
2974 | unsigned long flags; | |
2975 | ||
2976 | spin_lock_irqsave(&x->wait.lock, flags); | |
2977 | x->done += UINT_MAX/2; | |
2978 | __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, | |
2979 | 0, 0, NULL); | |
2980 | spin_unlock_irqrestore(&x->wait.lock, flags); | |
2981 | } | |
2982 | EXPORT_SYMBOL(complete_all); | |
2983 | ||
2984 | void fastcall __sched wait_for_completion(struct completion *x) | |
2985 | { | |
2986 | might_sleep(); | |
2987 | spin_lock_irq(&x->wait.lock); | |
2988 | if (!x->done) { | |
2989 | DECLARE_WAITQUEUE(wait, current); | |
2990 | ||
2991 | wait.flags |= WQ_FLAG_EXCLUSIVE; | |
2992 | __add_wait_queue_tail(&x->wait, &wait); | |
2993 | do { | |
2994 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
2995 | spin_unlock_irq(&x->wait.lock); | |
2996 | schedule(); | |
2997 | spin_lock_irq(&x->wait.lock); | |
2998 | } while (!x->done); | |
2999 | __remove_wait_queue(&x->wait, &wait); | |
3000 | } | |
3001 | x->done--; | |
3002 | spin_unlock_irq(&x->wait.lock); | |
3003 | } | |
3004 | EXPORT_SYMBOL(wait_for_completion); | |
3005 | ||
3006 | unsigned long fastcall __sched | |
3007 | wait_for_completion_timeout(struct completion *x, unsigned long timeout) | |
3008 | { | |
3009 | might_sleep(); | |
3010 | ||
3011 | spin_lock_irq(&x->wait.lock); | |
3012 | if (!x->done) { | |
3013 | DECLARE_WAITQUEUE(wait, current); | |
3014 | ||
3015 | wait.flags |= WQ_FLAG_EXCLUSIVE; | |
3016 | __add_wait_queue_tail(&x->wait, &wait); | |
3017 | do { | |
3018 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
3019 | spin_unlock_irq(&x->wait.lock); | |
3020 | timeout = schedule_timeout(timeout); | |
3021 | spin_lock_irq(&x->wait.lock); | |
3022 | if (!timeout) { | |
3023 | __remove_wait_queue(&x->wait, &wait); | |
3024 | goto out; | |
3025 | } | |
3026 | } while (!x->done); | |
3027 | __remove_wait_queue(&x->wait, &wait); | |
3028 | } | |
3029 | x->done--; | |
3030 | out: | |
3031 | spin_unlock_irq(&x->wait.lock); | |
3032 | return timeout; | |
3033 | } | |
3034 | EXPORT_SYMBOL(wait_for_completion_timeout); | |
3035 | ||
3036 | int fastcall __sched wait_for_completion_interruptible(struct completion *x) | |
3037 | { | |
3038 | int ret = 0; | |
3039 | ||
3040 | might_sleep(); | |
3041 | ||
3042 | spin_lock_irq(&x->wait.lock); | |
3043 | if (!x->done) { | |
3044 | DECLARE_WAITQUEUE(wait, current); | |
3045 | ||
3046 | wait.flags |= WQ_FLAG_EXCLUSIVE; | |
3047 | __add_wait_queue_tail(&x->wait, &wait); | |
3048 | do { | |
3049 | if (signal_pending(current)) { | |
3050 | ret = -ERESTARTSYS; | |
3051 | __remove_wait_queue(&x->wait, &wait); | |
3052 | goto out; | |
3053 | } | |
3054 | __set_current_state(TASK_INTERRUPTIBLE); | |
3055 | spin_unlock_irq(&x->wait.lock); | |
3056 | schedule(); | |
3057 | spin_lock_irq(&x->wait.lock); | |
3058 | } while (!x->done); | |
3059 | __remove_wait_queue(&x->wait, &wait); | |
3060 | } | |
3061 | x->done--; | |
3062 | out: | |
3063 | spin_unlock_irq(&x->wait.lock); | |
3064 | ||
3065 | return ret; | |
3066 | } | |
3067 | EXPORT_SYMBOL(wait_for_completion_interruptible); | |
3068 | ||
3069 | unsigned long fastcall __sched | |
3070 | wait_for_completion_interruptible_timeout(struct completion *x, | |
3071 | unsigned long timeout) | |
3072 | { | |
3073 | might_sleep(); | |
3074 | ||
3075 | spin_lock_irq(&x->wait.lock); | |
3076 | if (!x->done) { | |
3077 | DECLARE_WAITQUEUE(wait, current); | |
3078 | ||
3079 | wait.flags |= WQ_FLAG_EXCLUSIVE; | |
3080 | __add_wait_queue_tail(&x->wait, &wait); | |
3081 | do { | |
3082 | if (signal_pending(current)) { | |
3083 | timeout = -ERESTARTSYS; | |
3084 | __remove_wait_queue(&x->wait, &wait); | |
3085 | goto out; | |
3086 | } | |
3087 | __set_current_state(TASK_INTERRUPTIBLE); | |
3088 | spin_unlock_irq(&x->wait.lock); | |
3089 | timeout = schedule_timeout(timeout); | |
3090 | spin_lock_irq(&x->wait.lock); | |
3091 | if (!timeout) { | |
3092 | __remove_wait_queue(&x->wait, &wait); | |
3093 | goto out; | |
3094 | } | |
3095 | } while (!x->done); | |
3096 | __remove_wait_queue(&x->wait, &wait); | |
3097 | } | |
3098 | x->done--; | |
3099 | out: | |
3100 | spin_unlock_irq(&x->wait.lock); | |
3101 | return timeout; | |
3102 | } | |
3103 | EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); | |
3104 | ||
3105 | ||
3106 | #define SLEEP_ON_VAR \ | |
3107 | unsigned long flags; \ | |
3108 | wait_queue_t wait; \ | |
3109 | init_waitqueue_entry(&wait, current); | |
3110 | ||
3111 | #define SLEEP_ON_HEAD \ | |
3112 | spin_lock_irqsave(&q->lock,flags); \ | |
3113 | __add_wait_queue(q, &wait); \ | |
3114 | spin_unlock(&q->lock); | |
3115 | ||
3116 | #define SLEEP_ON_TAIL \ | |
3117 | spin_lock_irq(&q->lock); \ | |
3118 | __remove_wait_queue(q, &wait); \ | |
3119 | spin_unlock_irqrestore(&q->lock, flags); | |
3120 | ||
3121 | void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q) | |
3122 | { | |
3123 | SLEEP_ON_VAR | |
3124 | ||
3125 | current->state = TASK_INTERRUPTIBLE; | |
3126 | ||
3127 | SLEEP_ON_HEAD | |
3128 | schedule(); | |
3129 | SLEEP_ON_TAIL | |
3130 | } | |
3131 | ||
3132 | EXPORT_SYMBOL(interruptible_sleep_on); | |
3133 | ||
3134 | long fastcall __sched interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout) | |
3135 | { | |
3136 | SLEEP_ON_VAR | |
3137 | ||
3138 | current->state = TASK_INTERRUPTIBLE; | |
3139 | ||
3140 | SLEEP_ON_HEAD | |
3141 | timeout = schedule_timeout(timeout); | |
3142 | SLEEP_ON_TAIL | |
3143 | ||
3144 | return timeout; | |
3145 | } | |
3146 | ||
3147 | EXPORT_SYMBOL(interruptible_sleep_on_timeout); | |
3148 | ||
3149 | void fastcall __sched sleep_on(wait_queue_head_t *q) | |
3150 | { | |
3151 | SLEEP_ON_VAR | |
3152 | ||
3153 | current->state = TASK_UNINTERRUPTIBLE; | |
3154 | ||
3155 | SLEEP_ON_HEAD | |
3156 | schedule(); | |
3157 | SLEEP_ON_TAIL | |
3158 | } | |
3159 | ||
3160 | EXPORT_SYMBOL(sleep_on); | |
3161 | ||
3162 | long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout) | |
3163 | { | |
3164 | SLEEP_ON_VAR | |
3165 | ||
3166 | current->state = TASK_UNINTERRUPTIBLE; | |
3167 | ||
3168 | SLEEP_ON_HEAD | |
3169 | timeout = schedule_timeout(timeout); | |
3170 | SLEEP_ON_TAIL | |
3171 | ||
3172 | return timeout; | |
3173 | } | |
3174 | ||
3175 | EXPORT_SYMBOL(sleep_on_timeout); | |
3176 | ||
3177 | void set_user_nice(task_t *p, long nice) | |
3178 | { | |
3179 | unsigned long flags; | |
3180 | prio_array_t *array; | |
3181 | runqueue_t *rq; | |
3182 | int old_prio, new_prio, delta; | |
3183 | ||
3184 | if (TASK_NICE(p) == nice || nice < -20 || nice > 19) | |
3185 | return; | |
3186 | /* | |
3187 | * We have to be careful, if called from sys_setpriority(), | |
3188 | * the task might be in the middle of scheduling on another CPU. | |
3189 | */ | |
3190 | rq = task_rq_lock(p, &flags); | |
3191 | /* | |
3192 | * The RT priorities are set via sched_setscheduler(), but we still | |
3193 | * allow the 'normal' nice value to be set - but as expected | |
3194 | * it wont have any effect on scheduling until the task is | |
3195 | * not SCHED_NORMAL: | |
3196 | */ | |
3197 | if (rt_task(p)) { | |
3198 | p->static_prio = NICE_TO_PRIO(nice); | |
3199 | goto out_unlock; | |
3200 | } | |
3201 | array = p->array; | |
3202 | if (array) | |
3203 | dequeue_task(p, array); | |
3204 | ||
3205 | old_prio = p->prio; | |
3206 | new_prio = NICE_TO_PRIO(nice); | |
3207 | delta = new_prio - old_prio; | |
3208 | p->static_prio = NICE_TO_PRIO(nice); | |
3209 | p->prio += delta; | |
3210 | ||
3211 | if (array) { | |
3212 | enqueue_task(p, array); | |
3213 | /* | |
3214 | * If the task increased its priority or is running and | |
3215 | * lowered its priority, then reschedule its CPU: | |
3216 | */ | |
3217 | if (delta < 0 || (delta > 0 && task_running(rq, p))) | |
3218 | resched_task(rq->curr); | |
3219 | } | |
3220 | out_unlock: | |
3221 | task_rq_unlock(rq, &flags); | |
3222 | } | |
3223 | ||
3224 | EXPORT_SYMBOL(set_user_nice); | |
3225 | ||
3226 | #ifdef __ARCH_WANT_SYS_NICE | |
3227 | ||
3228 | /* | |
3229 | * sys_nice - change the priority of the current process. | |
3230 | * @increment: priority increment | |
3231 | * | |
3232 | * sys_setpriority is a more generic, but much slower function that | |
3233 | * does similar things. | |
3234 | */ | |
3235 | asmlinkage long sys_nice(int increment) | |
3236 | { | |
3237 | int retval; | |
3238 | long nice; | |
3239 | ||
3240 | /* | |
3241 | * Setpriority might change our priority at the same moment. | |
3242 | * We don't have to worry. Conceptually one call occurs first | |
3243 | * and we have a single winner. | |
3244 | */ | |
3245 | if (increment < 0) { | |
3246 | if (!capable(CAP_SYS_NICE)) | |
3247 | return -EPERM; | |
3248 | if (increment < -40) | |
3249 | increment = -40; | |
3250 | } | |
3251 | if (increment > 40) | |
3252 | increment = 40; | |
3253 | ||
3254 | nice = PRIO_TO_NICE(current->static_prio) + increment; | |
3255 | if (nice < -20) | |
3256 | nice = -20; | |
3257 | if (nice > 19) | |
3258 | nice = 19; | |
3259 | ||
3260 | retval = security_task_setnice(current, nice); | |
3261 | if (retval) | |
3262 | return retval; | |
3263 | ||
3264 | set_user_nice(current, nice); | |
3265 | return 0; | |
3266 | } | |
3267 | ||
3268 | #endif | |
3269 | ||
3270 | /** | |
3271 | * task_prio - return the priority value of a given task. | |
3272 | * @p: the task in question. | |
3273 | * | |
3274 | * This is the priority value as seen by users in /proc. | |
3275 | * RT tasks are offset by -200. Normal tasks are centered | |
3276 | * around 0, value goes from -16 to +15. | |
3277 | */ | |
3278 | int task_prio(const task_t *p) | |
3279 | { | |
3280 | return p->prio - MAX_RT_PRIO; | |
3281 | } | |
3282 | ||
3283 | /** | |
3284 | * task_nice - return the nice value of a given task. | |
3285 | * @p: the task in question. | |
3286 | */ | |
3287 | int task_nice(const task_t *p) | |
3288 | { | |
3289 | return TASK_NICE(p); | |
3290 | } | |
3291 | ||
3292 | /* | |
3293 | * The only users of task_nice are binfmt_elf and binfmt_elf32. | |
3294 | * binfmt_elf is no longer modular, but binfmt_elf32 still is. | |
3295 | * Therefore, task_nice is needed if there is a compat_mode. | |
3296 | */ | |
3297 | #ifdef CONFIG_COMPAT | |
3298 | EXPORT_SYMBOL_GPL(task_nice); | |
3299 | #endif | |
3300 | ||
3301 | /** | |
3302 | * idle_cpu - is a given cpu idle currently? | |
3303 | * @cpu: the processor in question. | |
3304 | */ | |
3305 | int idle_cpu(int cpu) | |
3306 | { | |
3307 | return cpu_curr(cpu) == cpu_rq(cpu)->idle; | |
3308 | } | |
3309 | ||
3310 | EXPORT_SYMBOL_GPL(idle_cpu); | |
3311 | ||
3312 | /** | |
3313 | * idle_task - return the idle task for a given cpu. | |
3314 | * @cpu: the processor in question. | |
3315 | */ | |
3316 | task_t *idle_task(int cpu) | |
3317 | { | |
3318 | return cpu_rq(cpu)->idle; | |
3319 | } | |
3320 | ||
3321 | /** | |
3322 | * find_process_by_pid - find a process with a matching PID value. | |
3323 | * @pid: the pid in question. | |
3324 | */ | |
3325 | static inline task_t *find_process_by_pid(pid_t pid) | |
3326 | { | |
3327 | return pid ? find_task_by_pid(pid) : current; | |
3328 | } | |
3329 | ||
3330 | /* Actually do priority change: must hold rq lock. */ | |
3331 | static void __setscheduler(struct task_struct *p, int policy, int prio) | |
3332 | { | |
3333 | BUG_ON(p->array); | |
3334 | p->policy = policy; | |
3335 | p->rt_priority = prio; | |
3336 | if (policy != SCHED_NORMAL) | |
3337 | p->prio = MAX_USER_RT_PRIO-1 - p->rt_priority; | |
3338 | else | |
3339 | p->prio = p->static_prio; | |
3340 | } | |
3341 | ||
3342 | /** | |
3343 | * sched_setscheduler - change the scheduling policy and/or RT priority of | |
3344 | * a thread. | |
3345 | * @p: the task in question. | |
3346 | * @policy: new policy. | |
3347 | * @param: structure containing the new RT priority. | |
3348 | */ | |
3349 | int sched_setscheduler(struct task_struct *p, int policy, struct sched_param *param) | |
3350 | { | |
3351 | int retval; | |
3352 | int oldprio, oldpolicy = -1; | |
3353 | prio_array_t *array; | |
3354 | unsigned long flags; | |
3355 | runqueue_t *rq; | |
3356 | ||
3357 | recheck: | |
3358 | /* double check policy once rq lock held */ | |
3359 | if (policy < 0) | |
3360 | policy = oldpolicy = p->policy; | |
3361 | else if (policy != SCHED_FIFO && policy != SCHED_RR && | |
3362 | policy != SCHED_NORMAL) | |
3363 | return -EINVAL; | |
3364 | /* | |
3365 | * Valid priorities for SCHED_FIFO and SCHED_RR are | |
3366 | * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0. | |
3367 | */ | |
3368 | if (param->sched_priority < 0 || | |
3369 | param->sched_priority > MAX_USER_RT_PRIO-1) | |
3370 | return -EINVAL; | |
3371 | if ((policy == SCHED_NORMAL) != (param->sched_priority == 0)) | |
3372 | return -EINVAL; | |
3373 | ||
3374 | if ((policy == SCHED_FIFO || policy == SCHED_RR) && | |
3375 | !capable(CAP_SYS_NICE)) | |
3376 | return -EPERM; | |
3377 | if ((current->euid != p->euid) && (current->euid != p->uid) && | |
3378 | !capable(CAP_SYS_NICE)) | |
3379 | return -EPERM; | |
3380 | ||
3381 | retval = security_task_setscheduler(p, policy, param); | |
3382 | if (retval) | |
3383 | return retval; | |
3384 | /* | |
3385 | * To be able to change p->policy safely, the apropriate | |
3386 | * runqueue lock must be held. | |
3387 | */ | |
3388 | rq = task_rq_lock(p, &flags); | |
3389 | /* recheck policy now with rq lock held */ | |
3390 | if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { | |
3391 | policy = oldpolicy = -1; | |
3392 | task_rq_unlock(rq, &flags); | |
3393 | goto recheck; | |
3394 | } | |
3395 | array = p->array; | |
3396 | if (array) | |
3397 | deactivate_task(p, rq); | |
3398 | oldprio = p->prio; | |
3399 | __setscheduler(p, policy, param->sched_priority); | |
3400 | if (array) { | |
3401 | __activate_task(p, rq); | |
3402 | /* | |
3403 | * Reschedule if we are currently running on this runqueue and | |
3404 | * our priority decreased, or if we are not currently running on | |
3405 | * this runqueue and our priority is higher than the current's | |
3406 | */ | |
3407 | if (task_running(rq, p)) { | |
3408 | if (p->prio > oldprio) | |
3409 | resched_task(rq->curr); | |
3410 | } else if (TASK_PREEMPTS_CURR(p, rq)) | |
3411 | resched_task(rq->curr); | |
3412 | } | |
3413 | task_rq_unlock(rq, &flags); | |
3414 | return 0; | |
3415 | } | |
3416 | EXPORT_SYMBOL_GPL(sched_setscheduler); | |
3417 | ||
3418 | static int do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) | |
3419 | { | |
3420 | int retval; | |
3421 | struct sched_param lparam; | |
3422 | struct task_struct *p; | |
3423 | ||
3424 | if (!param || pid < 0) | |
3425 | return -EINVAL; | |
3426 | if (copy_from_user(&lparam, param, sizeof(struct sched_param))) | |
3427 | return -EFAULT; | |
3428 | read_lock_irq(&tasklist_lock); | |
3429 | p = find_process_by_pid(pid); | |
3430 | if (!p) { | |
3431 | read_unlock_irq(&tasklist_lock); | |
3432 | return -ESRCH; | |
3433 | } | |
3434 | retval = sched_setscheduler(p, policy, &lparam); | |
3435 | read_unlock_irq(&tasklist_lock); | |
3436 | return retval; | |
3437 | } | |
3438 | ||
3439 | /** | |
3440 | * sys_sched_setscheduler - set/change the scheduler policy and RT priority | |
3441 | * @pid: the pid in question. | |
3442 | * @policy: new policy. | |
3443 | * @param: structure containing the new RT priority. | |
3444 | */ | |
3445 | asmlinkage long sys_sched_setscheduler(pid_t pid, int policy, | |
3446 | struct sched_param __user *param) | |
3447 | { | |
3448 | return do_sched_setscheduler(pid, policy, param); | |
3449 | } | |
3450 | ||
3451 | /** | |
3452 | * sys_sched_setparam - set/change the RT priority of a thread | |
3453 | * @pid: the pid in question. | |
3454 | * @param: structure containing the new RT priority. | |
3455 | */ | |
3456 | asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param) | |
3457 | { | |
3458 | return do_sched_setscheduler(pid, -1, param); | |
3459 | } | |
3460 | ||
3461 | /** | |
3462 | * sys_sched_getscheduler - get the policy (scheduling class) of a thread | |
3463 | * @pid: the pid in question. | |
3464 | */ | |
3465 | asmlinkage long sys_sched_getscheduler(pid_t pid) | |
3466 | { | |
3467 | int retval = -EINVAL; | |
3468 | task_t *p; | |
3469 | ||
3470 | if (pid < 0) | |
3471 | goto out_nounlock; | |
3472 | ||
3473 | retval = -ESRCH; | |
3474 | read_lock(&tasklist_lock); | |
3475 | p = find_process_by_pid(pid); | |
3476 | if (p) { | |
3477 | retval = security_task_getscheduler(p); | |
3478 | if (!retval) | |
3479 | retval = p->policy; | |
3480 | } | |
3481 | read_unlock(&tasklist_lock); | |
3482 | ||
3483 | out_nounlock: | |
3484 | return retval; | |
3485 | } | |
3486 | ||
3487 | /** | |
3488 | * sys_sched_getscheduler - get the RT priority of a thread | |
3489 | * @pid: the pid in question. | |
3490 | * @param: structure containing the RT priority. | |
3491 | */ | |
3492 | asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param) | |
3493 | { | |
3494 | struct sched_param lp; | |
3495 | int retval = -EINVAL; | |
3496 | task_t *p; | |
3497 | ||
3498 | if (!param || pid < 0) | |
3499 | goto out_nounlock; | |
3500 | ||
3501 | read_lock(&tasklist_lock); | |
3502 | p = find_process_by_pid(pid); | |
3503 | retval = -ESRCH; | |
3504 | if (!p) | |
3505 | goto out_unlock; | |
3506 | ||
3507 | retval = security_task_getscheduler(p); | |
3508 | if (retval) | |
3509 | goto out_unlock; | |
3510 | ||
3511 | lp.sched_priority = p->rt_priority; | |
3512 | read_unlock(&tasklist_lock); | |
3513 | ||
3514 | /* | |
3515 | * This one might sleep, we cannot do it with a spinlock held ... | |
3516 | */ | |
3517 | retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; | |
3518 | ||
3519 | out_nounlock: | |
3520 | return retval; | |
3521 | ||
3522 | out_unlock: | |
3523 | read_unlock(&tasklist_lock); | |
3524 | return retval; | |
3525 | } | |
3526 | ||
3527 | long sched_setaffinity(pid_t pid, cpumask_t new_mask) | |
3528 | { | |
3529 | task_t *p; | |
3530 | int retval; | |
3531 | cpumask_t cpus_allowed; | |
3532 | ||
3533 | lock_cpu_hotplug(); | |
3534 | read_lock(&tasklist_lock); | |
3535 | ||
3536 | p = find_process_by_pid(pid); | |
3537 | if (!p) { | |
3538 | read_unlock(&tasklist_lock); | |
3539 | unlock_cpu_hotplug(); | |
3540 | return -ESRCH; | |
3541 | } | |
3542 | ||
3543 | /* | |
3544 | * It is not safe to call set_cpus_allowed with the | |
3545 | * tasklist_lock held. We will bump the task_struct's | |
3546 | * usage count and then drop tasklist_lock. | |
3547 | */ | |
3548 | get_task_struct(p); | |
3549 | read_unlock(&tasklist_lock); | |
3550 | ||
3551 | retval = -EPERM; | |
3552 | if ((current->euid != p->euid) && (current->euid != p->uid) && | |
3553 | !capable(CAP_SYS_NICE)) | |
3554 | goto out_unlock; | |
3555 | ||
3556 | cpus_allowed = cpuset_cpus_allowed(p); | |
3557 | cpus_and(new_mask, new_mask, cpus_allowed); | |
3558 | retval = set_cpus_allowed(p, new_mask); | |
3559 | ||
3560 | out_unlock: | |
3561 | put_task_struct(p); | |
3562 | unlock_cpu_hotplug(); | |
3563 | return retval; | |
3564 | } | |
3565 | ||
3566 | static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, | |
3567 | cpumask_t *new_mask) | |
3568 | { | |
3569 | if (len < sizeof(cpumask_t)) { | |
3570 | memset(new_mask, 0, sizeof(cpumask_t)); | |
3571 | } else if (len > sizeof(cpumask_t)) { | |
3572 | len = sizeof(cpumask_t); | |
3573 | } | |
3574 | return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; | |
3575 | } | |
3576 | ||
3577 | /** | |
3578 | * sys_sched_setaffinity - set the cpu affinity of a process | |
3579 | * @pid: pid of the process | |
3580 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
3581 | * @user_mask_ptr: user-space pointer to the new cpu mask | |
3582 | */ | |
3583 | asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len, | |
3584 | unsigned long __user *user_mask_ptr) | |
3585 | { | |
3586 | cpumask_t new_mask; | |
3587 | int retval; | |
3588 | ||
3589 | retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask); | |
3590 | if (retval) | |
3591 | return retval; | |
3592 | ||
3593 | return sched_setaffinity(pid, new_mask); | |
3594 | } | |
3595 | ||
3596 | /* | |
3597 | * Represents all cpu's present in the system | |
3598 | * In systems capable of hotplug, this map could dynamically grow | |
3599 | * as new cpu's are detected in the system via any platform specific | |
3600 | * method, such as ACPI for e.g. | |
3601 | */ | |
3602 | ||
3603 | cpumask_t cpu_present_map; | |
3604 | EXPORT_SYMBOL(cpu_present_map); | |
3605 | ||
3606 | #ifndef CONFIG_SMP | |
3607 | cpumask_t cpu_online_map = CPU_MASK_ALL; | |
3608 | cpumask_t cpu_possible_map = CPU_MASK_ALL; | |
3609 | #endif | |
3610 | ||
3611 | long sched_getaffinity(pid_t pid, cpumask_t *mask) | |
3612 | { | |
3613 | int retval; | |
3614 | task_t *p; | |
3615 | ||
3616 | lock_cpu_hotplug(); | |
3617 | read_lock(&tasklist_lock); | |
3618 | ||
3619 | retval = -ESRCH; | |
3620 | p = find_process_by_pid(pid); | |
3621 | if (!p) | |
3622 | goto out_unlock; | |
3623 | ||
3624 | retval = 0; | |
3625 | cpus_and(*mask, p->cpus_allowed, cpu_possible_map); | |
3626 | ||
3627 | out_unlock: | |
3628 | read_unlock(&tasklist_lock); | |
3629 | unlock_cpu_hotplug(); | |
3630 | if (retval) | |
3631 | return retval; | |
3632 | ||
3633 | return 0; | |
3634 | } | |
3635 | ||
3636 | /** | |
3637 | * sys_sched_getaffinity - get the cpu affinity of a process | |
3638 | * @pid: pid of the process | |
3639 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
3640 | * @user_mask_ptr: user-space pointer to hold the current cpu mask | |
3641 | */ | |
3642 | asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len, | |
3643 | unsigned long __user *user_mask_ptr) | |
3644 | { | |
3645 | int ret; | |
3646 | cpumask_t mask; | |
3647 | ||
3648 | if (len < sizeof(cpumask_t)) | |
3649 | return -EINVAL; | |
3650 | ||
3651 | ret = sched_getaffinity(pid, &mask); | |
3652 | if (ret < 0) | |
3653 | return ret; | |
3654 | ||
3655 | if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t))) | |
3656 | return -EFAULT; | |
3657 | ||
3658 | return sizeof(cpumask_t); | |
3659 | } | |
3660 | ||
3661 | /** | |
3662 | * sys_sched_yield - yield the current processor to other threads. | |
3663 | * | |
3664 | * this function yields the current CPU by moving the calling thread | |
3665 | * to the expired array. If there are no other threads running on this | |
3666 | * CPU then this function will return. | |
3667 | */ | |
3668 | asmlinkage long sys_sched_yield(void) | |
3669 | { | |
3670 | runqueue_t *rq = this_rq_lock(); | |
3671 | prio_array_t *array = current->array; | |
3672 | prio_array_t *target = rq->expired; | |
3673 | ||
3674 | schedstat_inc(rq, yld_cnt); | |
3675 | /* | |
3676 | * We implement yielding by moving the task into the expired | |
3677 | * queue. | |
3678 | * | |
3679 | * (special rule: RT tasks will just roundrobin in the active | |
3680 | * array.) | |
3681 | */ | |
3682 | if (rt_task(current)) | |
3683 | target = rq->active; | |
3684 | ||
3685 | if (current->array->nr_active == 1) { | |
3686 | schedstat_inc(rq, yld_act_empty); | |
3687 | if (!rq->expired->nr_active) | |
3688 | schedstat_inc(rq, yld_both_empty); | |
3689 | } else if (!rq->expired->nr_active) | |
3690 | schedstat_inc(rq, yld_exp_empty); | |
3691 | ||
3692 | if (array != target) { | |
3693 | dequeue_task(current, array); | |
3694 | enqueue_task(current, target); | |
3695 | } else | |
3696 | /* | |
3697 | * requeue_task is cheaper so perform that if possible. | |
3698 | */ | |
3699 | requeue_task(current, array); | |
3700 | ||
3701 | /* | |
3702 | * Since we are going to call schedule() anyway, there's | |
3703 | * no need to preempt or enable interrupts: | |
3704 | */ | |
3705 | __release(rq->lock); | |
3706 | _raw_spin_unlock(&rq->lock); | |
3707 | preempt_enable_no_resched(); | |
3708 | ||
3709 | schedule(); | |
3710 | ||
3711 | return 0; | |
3712 | } | |
3713 | ||
3714 | static inline void __cond_resched(void) | |
3715 | { | |
3716 | do { | |
3717 | add_preempt_count(PREEMPT_ACTIVE); | |
3718 | schedule(); | |
3719 | sub_preempt_count(PREEMPT_ACTIVE); | |
3720 | } while (need_resched()); | |
3721 | } | |
3722 | ||
3723 | int __sched cond_resched(void) | |
3724 | { | |
3725 | if (need_resched()) { | |
3726 | __cond_resched(); | |
3727 | return 1; | |
3728 | } | |
3729 | return 0; | |
3730 | } | |
3731 | ||
3732 | EXPORT_SYMBOL(cond_resched); | |
3733 | ||
3734 | /* | |
3735 | * cond_resched_lock() - if a reschedule is pending, drop the given lock, | |
3736 | * call schedule, and on return reacquire the lock. | |
3737 | * | |
3738 | * This works OK both with and without CONFIG_PREEMPT. We do strange low-level | |
3739 | * operations here to prevent schedule() from being called twice (once via | |
3740 | * spin_unlock(), once by hand). | |
3741 | */ | |
3742 | int cond_resched_lock(spinlock_t * lock) | |
3743 | { | |
3744 | if (need_lockbreak(lock)) { | |
3745 | spin_unlock(lock); | |
3746 | cpu_relax(); | |
3747 | spin_lock(lock); | |
3748 | } | |
3749 | if (need_resched()) { | |
3750 | _raw_spin_unlock(lock); | |
3751 | preempt_enable_no_resched(); | |
3752 | __cond_resched(); | |
3753 | spin_lock(lock); | |
3754 | return 1; | |
3755 | } | |
3756 | return 0; | |
3757 | } | |
3758 | ||
3759 | EXPORT_SYMBOL(cond_resched_lock); | |
3760 | ||
3761 | int __sched cond_resched_softirq(void) | |
3762 | { | |
3763 | BUG_ON(!in_softirq()); | |
3764 | ||
3765 | if (need_resched()) { | |
3766 | __local_bh_enable(); | |
3767 | __cond_resched(); | |
3768 | local_bh_disable(); | |
3769 | return 1; | |
3770 | } | |
3771 | return 0; | |
3772 | } | |
3773 | ||
3774 | EXPORT_SYMBOL(cond_resched_softirq); | |
3775 | ||
3776 | ||
3777 | /** | |
3778 | * yield - yield the current processor to other threads. | |
3779 | * | |
3780 | * this is a shortcut for kernel-space yielding - it marks the | |
3781 | * thread runnable and calls sys_sched_yield(). | |
3782 | */ | |
3783 | void __sched yield(void) | |
3784 | { | |
3785 | set_current_state(TASK_RUNNING); | |
3786 | sys_sched_yield(); | |
3787 | } | |
3788 | ||
3789 | EXPORT_SYMBOL(yield); | |
3790 | ||
3791 | /* | |
3792 | * This task is about to go to sleep on IO. Increment rq->nr_iowait so | |
3793 | * that process accounting knows that this is a task in IO wait state. | |
3794 | * | |
3795 | * But don't do that if it is a deliberate, throttling IO wait (this task | |
3796 | * has set its backing_dev_info: the queue against which it should throttle) | |
3797 | */ | |
3798 | void __sched io_schedule(void) | |
3799 | { | |
3800 | struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id()); | |
3801 | ||
3802 | atomic_inc(&rq->nr_iowait); | |
3803 | schedule(); | |
3804 | atomic_dec(&rq->nr_iowait); | |
3805 | } | |
3806 | ||
3807 | EXPORT_SYMBOL(io_schedule); | |
3808 | ||
3809 | long __sched io_schedule_timeout(long timeout) | |
3810 | { | |
3811 | struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id()); | |
3812 | long ret; | |
3813 | ||
3814 | atomic_inc(&rq->nr_iowait); | |
3815 | ret = schedule_timeout(timeout); | |
3816 | atomic_dec(&rq->nr_iowait); | |
3817 | return ret; | |
3818 | } | |
3819 | ||
3820 | /** | |
3821 | * sys_sched_get_priority_max - return maximum RT priority. | |
3822 | * @policy: scheduling class. | |
3823 | * | |
3824 | * this syscall returns the maximum rt_priority that can be used | |
3825 | * by a given scheduling class. | |
3826 | */ | |
3827 | asmlinkage long sys_sched_get_priority_max(int policy) | |
3828 | { | |
3829 | int ret = -EINVAL; | |
3830 | ||
3831 | switch (policy) { | |
3832 | case SCHED_FIFO: | |
3833 | case SCHED_RR: | |
3834 | ret = MAX_USER_RT_PRIO-1; | |
3835 | break; | |
3836 | case SCHED_NORMAL: | |
3837 | ret = 0; | |
3838 | break; | |
3839 | } | |
3840 | return ret; | |
3841 | } | |
3842 | ||
3843 | /** | |
3844 | * sys_sched_get_priority_min - return minimum RT priority. | |
3845 | * @policy: scheduling class. | |
3846 | * | |
3847 | * this syscall returns the minimum rt_priority that can be used | |
3848 | * by a given scheduling class. | |
3849 | */ | |
3850 | asmlinkage long sys_sched_get_priority_min(int policy) | |
3851 | { | |
3852 | int ret = -EINVAL; | |
3853 | ||
3854 | switch (policy) { | |
3855 | case SCHED_FIFO: | |
3856 | case SCHED_RR: | |
3857 | ret = 1; | |
3858 | break; | |
3859 | case SCHED_NORMAL: | |
3860 | ret = 0; | |
3861 | } | |
3862 | return ret; | |
3863 | } | |
3864 | ||
3865 | /** | |
3866 | * sys_sched_rr_get_interval - return the default timeslice of a process. | |
3867 | * @pid: pid of the process. | |
3868 | * @interval: userspace pointer to the timeslice value. | |
3869 | * | |
3870 | * this syscall writes the default timeslice value of a given process | |
3871 | * into the user-space timespec buffer. A value of '0' means infinity. | |
3872 | */ | |
3873 | asmlinkage | |
3874 | long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval) | |
3875 | { | |
3876 | int retval = -EINVAL; | |
3877 | struct timespec t; | |
3878 | task_t *p; | |
3879 | ||
3880 | if (pid < 0) | |
3881 | goto out_nounlock; | |
3882 | ||
3883 | retval = -ESRCH; | |
3884 | read_lock(&tasklist_lock); | |
3885 | p = find_process_by_pid(pid); | |
3886 | if (!p) | |
3887 | goto out_unlock; | |
3888 | ||
3889 | retval = security_task_getscheduler(p); | |
3890 | if (retval) | |
3891 | goto out_unlock; | |
3892 | ||
3893 | jiffies_to_timespec(p->policy & SCHED_FIFO ? | |
3894 | 0 : task_timeslice(p), &t); | |
3895 | read_unlock(&tasklist_lock); | |
3896 | retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; | |
3897 | out_nounlock: | |
3898 | return retval; | |
3899 | out_unlock: | |
3900 | read_unlock(&tasklist_lock); | |
3901 | return retval; | |
3902 | } | |
3903 | ||
3904 | static inline struct task_struct *eldest_child(struct task_struct *p) | |
3905 | { | |
3906 | if (list_empty(&p->children)) return NULL; | |
3907 | return list_entry(p->children.next,struct task_struct,sibling); | |
3908 | } | |
3909 | ||
3910 | static inline struct task_struct *older_sibling(struct task_struct *p) | |
3911 | { | |
3912 | if (p->sibling.prev==&p->parent->children) return NULL; | |
3913 | return list_entry(p->sibling.prev,struct task_struct,sibling); | |
3914 | } | |
3915 | ||
3916 | static inline struct task_struct *younger_sibling(struct task_struct *p) | |
3917 | { | |
3918 | if (p->sibling.next==&p->parent->children) return NULL; | |
3919 | return list_entry(p->sibling.next,struct task_struct,sibling); | |
3920 | } | |
3921 | ||
3922 | static void show_task(task_t * p) | |
3923 | { | |
3924 | task_t *relative; | |
3925 | unsigned state; | |
3926 | unsigned long free = 0; | |
3927 | static const char *stat_nam[] = { "R", "S", "D", "T", "t", "Z", "X" }; | |
3928 | ||
3929 | printk("%-13.13s ", p->comm); | |
3930 | state = p->state ? __ffs(p->state) + 1 : 0; | |
3931 | if (state < ARRAY_SIZE(stat_nam)) | |
3932 | printk(stat_nam[state]); | |
3933 | else | |
3934 | printk("?"); | |
3935 | #if (BITS_PER_LONG == 32) | |
3936 | if (state == TASK_RUNNING) | |
3937 | printk(" running "); | |
3938 | else | |
3939 | printk(" %08lX ", thread_saved_pc(p)); | |
3940 | #else | |
3941 | if (state == TASK_RUNNING) | |
3942 | printk(" running task "); | |
3943 | else | |
3944 | printk(" %016lx ", thread_saved_pc(p)); | |
3945 | #endif | |
3946 | #ifdef CONFIG_DEBUG_STACK_USAGE | |
3947 | { | |
3948 | unsigned long * n = (unsigned long *) (p->thread_info+1); | |
3949 | while (!*n) | |
3950 | n++; | |
3951 | free = (unsigned long) n - (unsigned long)(p->thread_info+1); | |
3952 | } | |
3953 | #endif | |
3954 | printk("%5lu %5d %6d ", free, p->pid, p->parent->pid); | |
3955 | if ((relative = eldest_child(p))) | |
3956 | printk("%5d ", relative->pid); | |
3957 | else | |
3958 | printk(" "); | |
3959 | if ((relative = younger_sibling(p))) | |
3960 | printk("%7d", relative->pid); | |
3961 | else | |
3962 | printk(" "); | |
3963 | if ((relative = older_sibling(p))) | |
3964 | printk(" %5d", relative->pid); | |
3965 | else | |
3966 | printk(" "); | |
3967 | if (!p->mm) | |
3968 | printk(" (L-TLB)\n"); | |
3969 | else | |
3970 | printk(" (NOTLB)\n"); | |
3971 | ||
3972 | if (state != TASK_RUNNING) | |
3973 | show_stack(p, NULL); | |
3974 | } | |
3975 | ||
3976 | void show_state(void) | |
3977 | { | |
3978 | task_t *g, *p; | |
3979 | ||
3980 | #if (BITS_PER_LONG == 32) | |
3981 | printk("\n" | |
3982 | " sibling\n"); | |
3983 | printk(" task PC pid father child younger older\n"); | |
3984 | #else | |
3985 | printk("\n" | |
3986 | " sibling\n"); | |
3987 | printk(" task PC pid father child younger older\n"); | |
3988 | #endif | |
3989 | read_lock(&tasklist_lock); | |
3990 | do_each_thread(g, p) { | |
3991 | /* | |
3992 | * reset the NMI-timeout, listing all files on a slow | |
3993 | * console might take alot of time: | |
3994 | */ | |
3995 | touch_nmi_watchdog(); | |
3996 | show_task(p); | |
3997 | } while_each_thread(g, p); | |
3998 | ||
3999 | read_unlock(&tasklist_lock); | |
4000 | } | |
4001 | ||
4002 | void __devinit init_idle(task_t *idle, int cpu) | |
4003 | { | |
4004 | runqueue_t *rq = cpu_rq(cpu); | |
4005 | unsigned long flags; | |
4006 | ||
4007 | idle->sleep_avg = 0; | |
4008 | idle->array = NULL; | |
4009 | idle->prio = MAX_PRIO; | |
4010 | idle->state = TASK_RUNNING; | |
4011 | idle->cpus_allowed = cpumask_of_cpu(cpu); | |
4012 | set_task_cpu(idle, cpu); | |
4013 | ||
4014 | spin_lock_irqsave(&rq->lock, flags); | |
4015 | rq->curr = rq->idle = idle; | |
4016 | set_tsk_need_resched(idle); | |
4017 | spin_unlock_irqrestore(&rq->lock, flags); | |
4018 | ||
4019 | /* Set the preempt count _outside_ the spinlocks! */ | |
4020 | #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL) | |
4021 | idle->thread_info->preempt_count = (idle->lock_depth >= 0); | |
4022 | #else | |
4023 | idle->thread_info->preempt_count = 0; | |
4024 | #endif | |
4025 | } | |
4026 | ||
4027 | /* | |
4028 | * In a system that switches off the HZ timer nohz_cpu_mask | |
4029 | * indicates which cpus entered this state. This is used | |
4030 | * in the rcu update to wait only for active cpus. For system | |
4031 | * which do not switch off the HZ timer nohz_cpu_mask should | |
4032 | * always be CPU_MASK_NONE. | |
4033 | */ | |
4034 | cpumask_t nohz_cpu_mask = CPU_MASK_NONE; | |
4035 | ||
4036 | #ifdef CONFIG_SMP | |
4037 | /* | |
4038 | * This is how migration works: | |
4039 | * | |
4040 | * 1) we queue a migration_req_t structure in the source CPU's | |
4041 | * runqueue and wake up that CPU's migration thread. | |
4042 | * 2) we down() the locked semaphore => thread blocks. | |
4043 | * 3) migration thread wakes up (implicitly it forces the migrated | |
4044 | * thread off the CPU) | |
4045 | * 4) it gets the migration request and checks whether the migrated | |
4046 | * task is still in the wrong runqueue. | |
4047 | * 5) if it's in the wrong runqueue then the migration thread removes | |
4048 | * it and puts it into the right queue. | |
4049 | * 6) migration thread up()s the semaphore. | |
4050 | * 7) we wake up and the migration is done. | |
4051 | */ | |
4052 | ||
4053 | /* | |
4054 | * Change a given task's CPU affinity. Migrate the thread to a | |
4055 | * proper CPU and schedule it away if the CPU it's executing on | |
4056 | * is removed from the allowed bitmask. | |
4057 | * | |
4058 | * NOTE: the caller must have a valid reference to the task, the | |
4059 | * task must not exit() & deallocate itself prematurely. The | |
4060 | * call is not atomic; no spinlocks may be held. | |
4061 | */ | |
4062 | int set_cpus_allowed(task_t *p, cpumask_t new_mask) | |
4063 | { | |
4064 | unsigned long flags; | |
4065 | int ret = 0; | |
4066 | migration_req_t req; | |
4067 | runqueue_t *rq; | |
4068 | ||
4069 | rq = task_rq_lock(p, &flags); | |
4070 | if (!cpus_intersects(new_mask, cpu_online_map)) { | |
4071 | ret = -EINVAL; | |
4072 | goto out; | |
4073 | } | |
4074 | ||
4075 | p->cpus_allowed = new_mask; | |
4076 | /* Can the task run on the task's current CPU? If so, we're done */ | |
4077 | if (cpu_isset(task_cpu(p), new_mask)) | |
4078 | goto out; | |
4079 | ||
4080 | if (migrate_task(p, any_online_cpu(new_mask), &req)) { | |
4081 | /* Need help from migration thread: drop lock and wait. */ | |
4082 | task_rq_unlock(rq, &flags); | |
4083 | wake_up_process(rq->migration_thread); | |
4084 | wait_for_completion(&req.done); | |
4085 | tlb_migrate_finish(p->mm); | |
4086 | return 0; | |
4087 | } | |
4088 | out: | |
4089 | task_rq_unlock(rq, &flags); | |
4090 | return ret; | |
4091 | } | |
4092 | ||
4093 | EXPORT_SYMBOL_GPL(set_cpus_allowed); | |
4094 | ||
4095 | /* | |
4096 | * Move (not current) task off this cpu, onto dest cpu. We're doing | |
4097 | * this because either it can't run here any more (set_cpus_allowed() | |
4098 | * away from this CPU, or CPU going down), or because we're | |
4099 | * attempting to rebalance this task on exec (sched_exec). | |
4100 | * | |
4101 | * So we race with normal scheduler movements, but that's OK, as long | |
4102 | * as the task is no longer on this CPU. | |
4103 | */ | |
4104 | static void __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) | |
4105 | { | |
4106 | runqueue_t *rq_dest, *rq_src; | |
4107 | ||
4108 | if (unlikely(cpu_is_offline(dest_cpu))) | |
4109 | return; | |
4110 | ||
4111 | rq_src = cpu_rq(src_cpu); | |
4112 | rq_dest = cpu_rq(dest_cpu); | |
4113 | ||
4114 | double_rq_lock(rq_src, rq_dest); | |
4115 | /* Already moved. */ | |
4116 | if (task_cpu(p) != src_cpu) | |
4117 | goto out; | |
4118 | /* Affinity changed (again). */ | |
4119 | if (!cpu_isset(dest_cpu, p->cpus_allowed)) | |
4120 | goto out; | |
4121 | ||
4122 | set_task_cpu(p, dest_cpu); | |
4123 | if (p->array) { | |
4124 | /* | |
4125 | * Sync timestamp with rq_dest's before activating. | |
4126 | * The same thing could be achieved by doing this step | |
4127 | * afterwards, and pretending it was a local activate. | |
4128 | * This way is cleaner and logically correct. | |
4129 | */ | |
4130 | p->timestamp = p->timestamp - rq_src->timestamp_last_tick | |
4131 | + rq_dest->timestamp_last_tick; | |
4132 | deactivate_task(p, rq_src); | |
4133 | activate_task(p, rq_dest, 0); | |
4134 | if (TASK_PREEMPTS_CURR(p, rq_dest)) | |
4135 | resched_task(rq_dest->curr); | |
4136 | } | |
4137 | ||
4138 | out: | |
4139 | double_rq_unlock(rq_src, rq_dest); | |
4140 | } | |
4141 | ||
4142 | /* | |
4143 | * migration_thread - this is a highprio system thread that performs | |
4144 | * thread migration by bumping thread off CPU then 'pushing' onto | |
4145 | * another runqueue. | |
4146 | */ | |
4147 | static int migration_thread(void * data) | |
4148 | { | |
4149 | runqueue_t *rq; | |
4150 | int cpu = (long)data; | |
4151 | ||
4152 | rq = cpu_rq(cpu); | |
4153 | BUG_ON(rq->migration_thread != current); | |
4154 | ||
4155 | set_current_state(TASK_INTERRUPTIBLE); | |
4156 | while (!kthread_should_stop()) { | |
4157 | struct list_head *head; | |
4158 | migration_req_t *req; | |
4159 | ||
4160 | if (current->flags & PF_FREEZE) | |
4161 | refrigerator(PF_FREEZE); | |
4162 | ||
4163 | spin_lock_irq(&rq->lock); | |
4164 | ||
4165 | if (cpu_is_offline(cpu)) { | |
4166 | spin_unlock_irq(&rq->lock); | |
4167 | goto wait_to_die; | |
4168 | } | |
4169 | ||
4170 | if (rq->active_balance) { | |
4171 | active_load_balance(rq, cpu); | |
4172 | rq->active_balance = 0; | |
4173 | } | |
4174 | ||
4175 | head = &rq->migration_queue; | |
4176 | ||
4177 | if (list_empty(head)) { | |
4178 | spin_unlock_irq(&rq->lock); | |
4179 | schedule(); | |
4180 | set_current_state(TASK_INTERRUPTIBLE); | |
4181 | continue; | |
4182 | } | |
4183 | req = list_entry(head->next, migration_req_t, list); | |
4184 | list_del_init(head->next); | |
4185 | ||
4186 | if (req->type == REQ_MOVE_TASK) { | |
4187 | spin_unlock(&rq->lock); | |
4188 | __migrate_task(req->task, cpu, req->dest_cpu); | |
4189 | local_irq_enable(); | |
4190 | } else if (req->type == REQ_SET_DOMAIN) { | |
4191 | rq->sd = req->sd; | |
4192 | spin_unlock_irq(&rq->lock); | |
4193 | } else { | |
4194 | spin_unlock_irq(&rq->lock); | |
4195 | WARN_ON(1); | |
4196 | } | |
4197 | ||
4198 | complete(&req->done); | |
4199 | } | |
4200 | __set_current_state(TASK_RUNNING); | |
4201 | return 0; | |
4202 | ||
4203 | wait_to_die: | |
4204 | /* Wait for kthread_stop */ | |
4205 | set_current_state(TASK_INTERRUPTIBLE); | |
4206 | while (!kthread_should_stop()) { | |
4207 | schedule(); | |
4208 | set_current_state(TASK_INTERRUPTIBLE); | |
4209 | } | |
4210 | __set_current_state(TASK_RUNNING); | |
4211 | return 0; | |
4212 | } | |
4213 | ||
4214 | #ifdef CONFIG_HOTPLUG_CPU | |
4215 | /* Figure out where task on dead CPU should go, use force if neccessary. */ | |
4216 | static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *tsk) | |
4217 | { | |
4218 | int dest_cpu; | |
4219 | cpumask_t mask; | |
4220 | ||
4221 | /* On same node? */ | |
4222 | mask = node_to_cpumask(cpu_to_node(dead_cpu)); | |
4223 | cpus_and(mask, mask, tsk->cpus_allowed); | |
4224 | dest_cpu = any_online_cpu(mask); | |
4225 | ||
4226 | /* On any allowed CPU? */ | |
4227 | if (dest_cpu == NR_CPUS) | |
4228 | dest_cpu = any_online_cpu(tsk->cpus_allowed); | |
4229 | ||
4230 | /* No more Mr. Nice Guy. */ | |
4231 | if (dest_cpu == NR_CPUS) { | |
4232 | tsk->cpus_allowed = cpuset_cpus_allowed(tsk); | |
4233 | dest_cpu = any_online_cpu(tsk->cpus_allowed); | |
4234 | ||
4235 | /* | |
4236 | * Don't tell them about moving exiting tasks or | |
4237 | * kernel threads (both mm NULL), since they never | |
4238 | * leave kernel. | |
4239 | */ | |
4240 | if (tsk->mm && printk_ratelimit()) | |
4241 | printk(KERN_INFO "process %d (%s) no " | |
4242 | "longer affine to cpu%d\n", | |
4243 | tsk->pid, tsk->comm, dead_cpu); | |
4244 | } | |
4245 | __migrate_task(tsk, dead_cpu, dest_cpu); | |
4246 | } | |
4247 | ||
4248 | /* | |
4249 | * While a dead CPU has no uninterruptible tasks queued at this point, | |
4250 | * it might still have a nonzero ->nr_uninterruptible counter, because | |
4251 | * for performance reasons the counter is not stricly tracking tasks to | |
4252 | * their home CPUs. So we just add the counter to another CPU's counter, | |
4253 | * to keep the global sum constant after CPU-down: | |
4254 | */ | |
4255 | static void migrate_nr_uninterruptible(runqueue_t *rq_src) | |
4256 | { | |
4257 | runqueue_t *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL)); | |
4258 | unsigned long flags; | |
4259 | ||
4260 | local_irq_save(flags); | |
4261 | double_rq_lock(rq_src, rq_dest); | |
4262 | rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible; | |
4263 | rq_src->nr_uninterruptible = 0; | |
4264 | double_rq_unlock(rq_src, rq_dest); | |
4265 | local_irq_restore(flags); | |
4266 | } | |
4267 | ||
4268 | /* Run through task list and migrate tasks from the dead cpu. */ | |
4269 | static void migrate_live_tasks(int src_cpu) | |
4270 | { | |
4271 | struct task_struct *tsk, *t; | |
4272 | ||
4273 | write_lock_irq(&tasklist_lock); | |
4274 | ||
4275 | do_each_thread(t, tsk) { | |
4276 | if (tsk == current) | |
4277 | continue; | |
4278 | ||
4279 | if (task_cpu(tsk) == src_cpu) | |
4280 | move_task_off_dead_cpu(src_cpu, tsk); | |
4281 | } while_each_thread(t, tsk); | |
4282 | ||
4283 | write_unlock_irq(&tasklist_lock); | |
4284 | } | |
4285 | ||
4286 | /* Schedules idle task to be the next runnable task on current CPU. | |
4287 | * It does so by boosting its priority to highest possible and adding it to | |
4288 | * the _front_ of runqueue. Used by CPU offline code. | |
4289 | */ | |
4290 | void sched_idle_next(void) | |
4291 | { | |
4292 | int cpu = smp_processor_id(); | |
4293 | runqueue_t *rq = this_rq(); | |
4294 | struct task_struct *p = rq->idle; | |
4295 | unsigned long flags; | |
4296 | ||
4297 | /* cpu has to be offline */ | |
4298 | BUG_ON(cpu_online(cpu)); | |
4299 | ||
4300 | /* Strictly not necessary since rest of the CPUs are stopped by now | |
4301 | * and interrupts disabled on current cpu. | |
4302 | */ | |
4303 | spin_lock_irqsave(&rq->lock, flags); | |
4304 | ||
4305 | __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1); | |
4306 | /* Add idle task to _front_ of it's priority queue */ | |
4307 | __activate_idle_task(p, rq); | |
4308 | ||
4309 | spin_unlock_irqrestore(&rq->lock, flags); | |
4310 | } | |
4311 | ||
4312 | /* Ensures that the idle task is using init_mm right before its cpu goes | |
4313 | * offline. | |
4314 | */ | |
4315 | void idle_task_exit(void) | |
4316 | { | |
4317 | struct mm_struct *mm = current->active_mm; | |
4318 | ||
4319 | BUG_ON(cpu_online(smp_processor_id())); | |
4320 | ||
4321 | if (mm != &init_mm) | |
4322 | switch_mm(mm, &init_mm, current); | |
4323 | mmdrop(mm); | |
4324 | } | |
4325 | ||
4326 | static void migrate_dead(unsigned int dead_cpu, task_t *tsk) | |
4327 | { | |
4328 | struct runqueue *rq = cpu_rq(dead_cpu); | |
4329 | ||
4330 | /* Must be exiting, otherwise would be on tasklist. */ | |
4331 | BUG_ON(tsk->exit_state != EXIT_ZOMBIE && tsk->exit_state != EXIT_DEAD); | |
4332 | ||
4333 | /* Cannot have done final schedule yet: would have vanished. */ | |
4334 | BUG_ON(tsk->flags & PF_DEAD); | |
4335 | ||
4336 | get_task_struct(tsk); | |
4337 | ||
4338 | /* | |
4339 | * Drop lock around migration; if someone else moves it, | |
4340 | * that's OK. No task can be added to this CPU, so iteration is | |
4341 | * fine. | |
4342 | */ | |
4343 | spin_unlock_irq(&rq->lock); | |
4344 | move_task_off_dead_cpu(dead_cpu, tsk); | |
4345 | spin_lock_irq(&rq->lock); | |
4346 | ||
4347 | put_task_struct(tsk); | |
4348 | } | |
4349 | ||
4350 | /* release_task() removes task from tasklist, so we won't find dead tasks. */ | |
4351 | static void migrate_dead_tasks(unsigned int dead_cpu) | |
4352 | { | |
4353 | unsigned arr, i; | |
4354 | struct runqueue *rq = cpu_rq(dead_cpu); | |
4355 | ||
4356 | for (arr = 0; arr < 2; arr++) { | |
4357 | for (i = 0; i < MAX_PRIO; i++) { | |
4358 | struct list_head *list = &rq->arrays[arr].queue[i]; | |
4359 | while (!list_empty(list)) | |
4360 | migrate_dead(dead_cpu, | |
4361 | list_entry(list->next, task_t, | |
4362 | run_list)); | |
4363 | } | |
4364 | } | |
4365 | } | |
4366 | #endif /* CONFIG_HOTPLUG_CPU */ | |
4367 | ||
4368 | /* | |
4369 | * migration_call - callback that gets triggered when a CPU is added. | |
4370 | * Here we can start up the necessary migration thread for the new CPU. | |
4371 | */ | |
4372 | static int migration_call(struct notifier_block *nfb, unsigned long action, | |
4373 | void *hcpu) | |
4374 | { | |
4375 | int cpu = (long)hcpu; | |
4376 | struct task_struct *p; | |
4377 | struct runqueue *rq; | |
4378 | unsigned long flags; | |
4379 | ||
4380 | switch (action) { | |
4381 | case CPU_UP_PREPARE: | |
4382 | p = kthread_create(migration_thread, hcpu, "migration/%d",cpu); | |
4383 | if (IS_ERR(p)) | |
4384 | return NOTIFY_BAD; | |
4385 | p->flags |= PF_NOFREEZE; | |
4386 | kthread_bind(p, cpu); | |
4387 | /* Must be high prio: stop_machine expects to yield to it. */ | |
4388 | rq = task_rq_lock(p, &flags); | |
4389 | __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1); | |
4390 | task_rq_unlock(rq, &flags); | |
4391 | cpu_rq(cpu)->migration_thread = p; | |
4392 | break; | |
4393 | case CPU_ONLINE: | |
4394 | /* Strictly unneccessary, as first user will wake it. */ | |
4395 | wake_up_process(cpu_rq(cpu)->migration_thread); | |
4396 | break; | |
4397 | #ifdef CONFIG_HOTPLUG_CPU | |
4398 | case CPU_UP_CANCELED: | |
4399 | /* Unbind it from offline cpu so it can run. Fall thru. */ | |
4400 | kthread_bind(cpu_rq(cpu)->migration_thread,smp_processor_id()); | |
4401 | kthread_stop(cpu_rq(cpu)->migration_thread); | |
4402 | cpu_rq(cpu)->migration_thread = NULL; | |
4403 | break; | |
4404 | case CPU_DEAD: | |
4405 | migrate_live_tasks(cpu); | |
4406 | rq = cpu_rq(cpu); | |
4407 | kthread_stop(rq->migration_thread); | |
4408 | rq->migration_thread = NULL; | |
4409 | /* Idle task back to normal (off runqueue, low prio) */ | |
4410 | rq = task_rq_lock(rq->idle, &flags); | |
4411 | deactivate_task(rq->idle, rq); | |
4412 | rq->idle->static_prio = MAX_PRIO; | |
4413 | __setscheduler(rq->idle, SCHED_NORMAL, 0); | |
4414 | migrate_dead_tasks(cpu); | |
4415 | task_rq_unlock(rq, &flags); | |
4416 | migrate_nr_uninterruptible(rq); | |
4417 | BUG_ON(rq->nr_running != 0); | |
4418 | ||
4419 | /* No need to migrate the tasks: it was best-effort if | |
4420 | * they didn't do lock_cpu_hotplug(). Just wake up | |
4421 | * the requestors. */ | |
4422 | spin_lock_irq(&rq->lock); | |
4423 | while (!list_empty(&rq->migration_queue)) { | |
4424 | migration_req_t *req; | |
4425 | req = list_entry(rq->migration_queue.next, | |
4426 | migration_req_t, list); | |
4427 | BUG_ON(req->type != REQ_MOVE_TASK); | |
4428 | list_del_init(&req->list); | |
4429 | complete(&req->done); | |
4430 | } | |
4431 | spin_unlock_irq(&rq->lock); | |
4432 | break; | |
4433 | #endif | |
4434 | } | |
4435 | return NOTIFY_OK; | |
4436 | } | |
4437 | ||
4438 | /* Register at highest priority so that task migration (migrate_all_tasks) | |
4439 | * happens before everything else. | |
4440 | */ | |
4441 | static struct notifier_block __devinitdata migration_notifier = { | |
4442 | .notifier_call = migration_call, | |
4443 | .priority = 10 | |
4444 | }; | |
4445 | ||
4446 | int __init migration_init(void) | |
4447 | { | |
4448 | void *cpu = (void *)(long)smp_processor_id(); | |
4449 | /* Start one for boot CPU. */ | |
4450 | migration_call(&migration_notifier, CPU_UP_PREPARE, cpu); | |
4451 | migration_call(&migration_notifier, CPU_ONLINE, cpu); | |
4452 | register_cpu_notifier(&migration_notifier); | |
4453 | return 0; | |
4454 | } | |
4455 | #endif | |
4456 | ||
4457 | #ifdef CONFIG_SMP | |
4458 | #define SCHED_DOMAIN_DEBUG | |
4459 | #ifdef SCHED_DOMAIN_DEBUG | |
4460 | static void sched_domain_debug(struct sched_domain *sd, int cpu) | |
4461 | { | |
4462 | int level = 0; | |
4463 | ||
4464 | printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); | |
4465 | ||
4466 | do { | |
4467 | int i; | |
4468 | char str[NR_CPUS]; | |
4469 | struct sched_group *group = sd->groups; | |
4470 | cpumask_t groupmask; | |
4471 | ||
4472 | cpumask_scnprintf(str, NR_CPUS, sd->span); | |
4473 | cpus_clear(groupmask); | |
4474 | ||
4475 | printk(KERN_DEBUG); | |
4476 | for (i = 0; i < level + 1; i++) | |
4477 | printk(" "); | |
4478 | printk("domain %d: ", level); | |
4479 | ||
4480 | if (!(sd->flags & SD_LOAD_BALANCE)) { | |
4481 | printk("does not load-balance\n"); | |
4482 | if (sd->parent) | |
4483 | printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain has parent"); | |
4484 | break; | |
4485 | } | |
4486 | ||
4487 | printk("span %s\n", str); | |
4488 | ||
4489 | if (!cpu_isset(cpu, sd->span)) | |
4490 | printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu); | |
4491 | if (!cpu_isset(cpu, group->cpumask)) | |
4492 | printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu); | |
4493 | ||
4494 | printk(KERN_DEBUG); | |
4495 | for (i = 0; i < level + 2; i++) | |
4496 | printk(" "); | |
4497 | printk("groups:"); | |
4498 | do { | |
4499 | if (!group) { | |
4500 | printk("\n"); | |
4501 | printk(KERN_ERR "ERROR: group is NULL\n"); | |
4502 | break; | |
4503 | } | |
4504 | ||
4505 | if (!group->cpu_power) { | |
4506 | printk("\n"); | |
4507 | printk(KERN_ERR "ERROR: domain->cpu_power not set\n"); | |
4508 | } | |
4509 | ||
4510 | if (!cpus_weight(group->cpumask)) { | |
4511 | printk("\n"); | |
4512 | printk(KERN_ERR "ERROR: empty group\n"); | |
4513 | } | |
4514 | ||
4515 | if (cpus_intersects(groupmask, group->cpumask)) { | |
4516 | printk("\n"); | |
4517 | printk(KERN_ERR "ERROR: repeated CPUs\n"); | |
4518 | } | |
4519 | ||
4520 | cpus_or(groupmask, groupmask, group->cpumask); | |
4521 | ||
4522 | cpumask_scnprintf(str, NR_CPUS, group->cpumask); | |
4523 | printk(" %s", str); | |
4524 | ||
4525 | group = group->next; | |
4526 | } while (group != sd->groups); | |
4527 | printk("\n"); | |
4528 | ||
4529 | if (!cpus_equal(sd->span, groupmask)) | |
4530 | printk(KERN_ERR "ERROR: groups don't span domain->span\n"); | |
4531 | ||
4532 | level++; | |
4533 | sd = sd->parent; | |
4534 | ||
4535 | if (sd) { | |
4536 | if (!cpus_subset(groupmask, sd->span)) | |
4537 | printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n"); | |
4538 | } | |
4539 | ||
4540 | } while (sd); | |
4541 | } | |
4542 | #else | |
4543 | #define sched_domain_debug(sd, cpu) {} | |
4544 | #endif | |
4545 | ||
4546 | /* | |
4547 | * Attach the domain 'sd' to 'cpu' as its base domain. Callers must | |
4548 | * hold the hotplug lock. | |
4549 | */ | |
4550 | void __devinit cpu_attach_domain(struct sched_domain *sd, int cpu) | |
4551 | { | |
4552 | migration_req_t req; | |
4553 | unsigned long flags; | |
4554 | runqueue_t *rq = cpu_rq(cpu); | |
4555 | int local = 1; | |
4556 | ||
4557 | sched_domain_debug(sd, cpu); | |
4558 | ||
4559 | spin_lock_irqsave(&rq->lock, flags); | |
4560 | ||
4561 | if (cpu == smp_processor_id() || !cpu_online(cpu)) { | |
4562 | rq->sd = sd; | |
4563 | } else { | |
4564 | init_completion(&req.done); | |
4565 | req.type = REQ_SET_DOMAIN; | |
4566 | req.sd = sd; | |
4567 | list_add(&req.list, &rq->migration_queue); | |
4568 | local = 0; | |
4569 | } | |
4570 | ||
4571 | spin_unlock_irqrestore(&rq->lock, flags); | |
4572 | ||
4573 | if (!local) { | |
4574 | wake_up_process(rq->migration_thread); | |
4575 | wait_for_completion(&req.done); | |
4576 | } | |
4577 | } | |
4578 | ||
4579 | /* cpus with isolated domains */ | |
4580 | cpumask_t __devinitdata cpu_isolated_map = CPU_MASK_NONE; | |
4581 | ||
4582 | /* Setup the mask of cpus configured for isolated domains */ | |
4583 | static int __init isolated_cpu_setup(char *str) | |
4584 | { | |
4585 | int ints[NR_CPUS], i; | |
4586 | ||
4587 | str = get_options(str, ARRAY_SIZE(ints), ints); | |
4588 | cpus_clear(cpu_isolated_map); | |
4589 | for (i = 1; i <= ints[0]; i++) | |
4590 | if (ints[i] < NR_CPUS) | |
4591 | cpu_set(ints[i], cpu_isolated_map); | |
4592 | return 1; | |
4593 | } | |
4594 | ||
4595 | __setup ("isolcpus=", isolated_cpu_setup); | |
4596 | ||
4597 | /* | |
4598 | * init_sched_build_groups takes an array of groups, the cpumask we wish | |
4599 | * to span, and a pointer to a function which identifies what group a CPU | |
4600 | * belongs to. The return value of group_fn must be a valid index into the | |
4601 | * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we | |
4602 | * keep track of groups covered with a cpumask_t). | |
4603 | * | |
4604 | * init_sched_build_groups will build a circular linked list of the groups | |
4605 | * covered by the given span, and will set each group's ->cpumask correctly, | |
4606 | * and ->cpu_power to 0. | |
4607 | */ | |
4608 | void __devinit init_sched_build_groups(struct sched_group groups[], | |
4609 | cpumask_t span, int (*group_fn)(int cpu)) | |
4610 | { | |
4611 | struct sched_group *first = NULL, *last = NULL; | |
4612 | cpumask_t covered = CPU_MASK_NONE; | |
4613 | int i; | |
4614 | ||
4615 | for_each_cpu_mask(i, span) { | |
4616 | int group = group_fn(i); | |
4617 | struct sched_group *sg = &groups[group]; | |
4618 | int j; | |
4619 | ||
4620 | if (cpu_isset(i, covered)) | |
4621 | continue; | |
4622 | ||
4623 | sg->cpumask = CPU_MASK_NONE; | |
4624 | sg->cpu_power = 0; | |
4625 | ||
4626 | for_each_cpu_mask(j, span) { | |
4627 | if (group_fn(j) != group) | |
4628 | continue; | |
4629 | ||
4630 | cpu_set(j, covered); | |
4631 | cpu_set(j, sg->cpumask); | |
4632 | } | |
4633 | if (!first) | |
4634 | first = sg; | |
4635 | if (last) | |
4636 | last->next = sg; | |
4637 | last = sg; | |
4638 | } | |
4639 | last->next = first; | |
4640 | } | |
4641 | ||
4642 | ||
4643 | #ifdef ARCH_HAS_SCHED_DOMAIN | |
4644 | extern void __devinit arch_init_sched_domains(void); | |
4645 | extern void __devinit arch_destroy_sched_domains(void); | |
4646 | #else | |
4647 | #ifdef CONFIG_SCHED_SMT | |
4648 | static DEFINE_PER_CPU(struct sched_domain, cpu_domains); | |
4649 | static struct sched_group sched_group_cpus[NR_CPUS]; | |
4650 | static int __devinit cpu_to_cpu_group(int cpu) | |
4651 | { | |
4652 | return cpu; | |
4653 | } | |
4654 | #endif | |
4655 | ||
4656 | static DEFINE_PER_CPU(struct sched_domain, phys_domains); | |
4657 | static struct sched_group sched_group_phys[NR_CPUS]; | |
4658 | static int __devinit cpu_to_phys_group(int cpu) | |
4659 | { | |
4660 | #ifdef CONFIG_SCHED_SMT | |
4661 | return first_cpu(cpu_sibling_map[cpu]); | |
4662 | #else | |
4663 | return cpu; | |
4664 | #endif | |
4665 | } | |
4666 | ||
4667 | #ifdef CONFIG_NUMA | |
4668 | ||
4669 | static DEFINE_PER_CPU(struct sched_domain, node_domains); | |
4670 | static struct sched_group sched_group_nodes[MAX_NUMNODES]; | |
4671 | static int __devinit cpu_to_node_group(int cpu) | |
4672 | { | |
4673 | return cpu_to_node(cpu); | |
4674 | } | |
4675 | #endif | |
4676 | ||
4677 | #if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA) | |
4678 | /* | |
4679 | * The domains setup code relies on siblings not spanning | |
4680 | * multiple nodes. Make sure the architecture has a proper | |
4681 | * siblings map: | |
4682 | */ | |
4683 | static void check_sibling_maps(void) | |
4684 | { | |
4685 | int i, j; | |
4686 | ||
4687 | for_each_online_cpu(i) { | |
4688 | for_each_cpu_mask(j, cpu_sibling_map[i]) { | |
4689 | if (cpu_to_node(i) != cpu_to_node(j)) { | |
4690 | printk(KERN_INFO "warning: CPU %d siblings map " | |
4691 | "to different node - isolating " | |
4692 | "them.\n", i); | |
4693 | cpu_sibling_map[i] = cpumask_of_cpu(i); | |
4694 | break; | |
4695 | } | |
4696 | } | |
4697 | } | |
4698 | } | |
4699 | #endif | |
4700 | ||
4701 | /* | |
4702 | * Set up scheduler domains and groups. Callers must hold the hotplug lock. | |
4703 | */ | |
4704 | static void __devinit arch_init_sched_domains(void) | |
4705 | { | |
4706 | int i; | |
4707 | cpumask_t cpu_default_map; | |
4708 | ||
4709 | #if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA) | |
4710 | check_sibling_maps(); | |
4711 | #endif | |
4712 | /* | |
4713 | * Setup mask for cpus without special case scheduling requirements. | |
4714 | * For now this just excludes isolated cpus, but could be used to | |
4715 | * exclude other special cases in the future. | |
4716 | */ | |
4717 | cpus_complement(cpu_default_map, cpu_isolated_map); | |
4718 | cpus_and(cpu_default_map, cpu_default_map, cpu_online_map); | |
4719 | ||
4720 | /* | |
4721 | * Set up domains. Isolated domains just stay on the dummy domain. | |
4722 | */ | |
4723 | for_each_cpu_mask(i, cpu_default_map) { | |
4724 | int group; | |
4725 | struct sched_domain *sd = NULL, *p; | |
4726 | cpumask_t nodemask = node_to_cpumask(cpu_to_node(i)); | |
4727 | ||
4728 | cpus_and(nodemask, nodemask, cpu_default_map); | |
4729 | ||
4730 | #ifdef CONFIG_NUMA | |
4731 | sd = &per_cpu(node_domains, i); | |
4732 | group = cpu_to_node_group(i); | |
4733 | *sd = SD_NODE_INIT; | |
4734 | sd->span = cpu_default_map; | |
4735 | sd->groups = &sched_group_nodes[group]; | |
4736 | #endif | |
4737 | ||
4738 | p = sd; | |
4739 | sd = &per_cpu(phys_domains, i); | |
4740 | group = cpu_to_phys_group(i); | |
4741 | *sd = SD_CPU_INIT; | |
4742 | sd->span = nodemask; | |
4743 | sd->parent = p; | |
4744 | sd->groups = &sched_group_phys[group]; | |
4745 | ||
4746 | #ifdef CONFIG_SCHED_SMT | |
4747 | p = sd; | |
4748 | sd = &per_cpu(cpu_domains, i); | |
4749 | group = cpu_to_cpu_group(i); | |
4750 | *sd = SD_SIBLING_INIT; | |
4751 | sd->span = cpu_sibling_map[i]; | |
4752 | cpus_and(sd->span, sd->span, cpu_default_map); | |
4753 | sd->parent = p; | |
4754 | sd->groups = &sched_group_cpus[group]; | |
4755 | #endif | |
4756 | } | |
4757 | ||
4758 | #ifdef CONFIG_SCHED_SMT | |
4759 | /* Set up CPU (sibling) groups */ | |
4760 | for_each_online_cpu(i) { | |
4761 | cpumask_t this_sibling_map = cpu_sibling_map[i]; | |
4762 | cpus_and(this_sibling_map, this_sibling_map, cpu_default_map); | |
4763 | if (i != first_cpu(this_sibling_map)) | |
4764 | continue; | |
4765 | ||
4766 | init_sched_build_groups(sched_group_cpus, this_sibling_map, | |
4767 | &cpu_to_cpu_group); | |
4768 | } | |
4769 | #endif | |
4770 | ||
4771 | /* Set up physical groups */ | |
4772 | for (i = 0; i < MAX_NUMNODES; i++) { | |
4773 | cpumask_t nodemask = node_to_cpumask(i); | |
4774 | ||
4775 | cpus_and(nodemask, nodemask, cpu_default_map); | |
4776 | if (cpus_empty(nodemask)) | |
4777 | continue; | |
4778 | ||
4779 | init_sched_build_groups(sched_group_phys, nodemask, | |
4780 | &cpu_to_phys_group); | |
4781 | } | |
4782 | ||
4783 | #ifdef CONFIG_NUMA | |
4784 | /* Set up node groups */ | |
4785 | init_sched_build_groups(sched_group_nodes, cpu_default_map, | |
4786 | &cpu_to_node_group); | |
4787 | #endif | |
4788 | ||
4789 | /* Calculate CPU power for physical packages and nodes */ | |
4790 | for_each_cpu_mask(i, cpu_default_map) { | |
4791 | int power; | |
4792 | struct sched_domain *sd; | |
4793 | #ifdef CONFIG_SCHED_SMT | |
4794 | sd = &per_cpu(cpu_domains, i); | |
4795 | power = SCHED_LOAD_SCALE; | |
4796 | sd->groups->cpu_power = power; | |
4797 | #endif | |
4798 | ||
4799 | sd = &per_cpu(phys_domains, i); | |
4800 | power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE * | |
4801 | (cpus_weight(sd->groups->cpumask)-1) / 10; | |
4802 | sd->groups->cpu_power = power; | |
4803 | ||
4804 | #ifdef CONFIG_NUMA | |
4805 | if (i == first_cpu(sd->groups->cpumask)) { | |
4806 | /* Only add "power" once for each physical package. */ | |
4807 | sd = &per_cpu(node_domains, i); | |
4808 | sd->groups->cpu_power += power; | |
4809 | } | |
4810 | #endif | |
4811 | } | |
4812 | ||
4813 | /* Attach the domains */ | |
4814 | for_each_online_cpu(i) { | |
4815 | struct sched_domain *sd; | |
4816 | #ifdef CONFIG_SCHED_SMT | |
4817 | sd = &per_cpu(cpu_domains, i); | |
4818 | #else | |
4819 | sd = &per_cpu(phys_domains, i); | |
4820 | #endif | |
4821 | cpu_attach_domain(sd, i); | |
4822 | } | |
4823 | } | |
4824 | ||
4825 | #ifdef CONFIG_HOTPLUG_CPU | |
4826 | static void __devinit arch_destroy_sched_domains(void) | |
4827 | { | |
4828 | /* Do nothing: everything is statically allocated. */ | |
4829 | } | |
4830 | #endif | |
4831 | ||
4832 | #endif /* ARCH_HAS_SCHED_DOMAIN */ | |
4833 | ||
4834 | /* | |
4835 | * Initial dummy domain for early boot and for hotplug cpu. Being static, | |
4836 | * it is initialized to zero, so all balancing flags are cleared which is | |
4837 | * what we want. | |
4838 | */ | |
4839 | static struct sched_domain sched_domain_dummy; | |
4840 | ||
4841 | #ifdef CONFIG_HOTPLUG_CPU | |
4842 | /* | |
4843 | * Force a reinitialization of the sched domains hierarchy. The domains | |
4844 | * and groups cannot be updated in place without racing with the balancing | |
4845 | * code, so we temporarily attach all running cpus to a "dummy" domain | |
4846 | * which will prevent rebalancing while the sched domains are recalculated. | |
4847 | */ | |
4848 | static int update_sched_domains(struct notifier_block *nfb, | |
4849 | unsigned long action, void *hcpu) | |
4850 | { | |
4851 | int i; | |
4852 | ||
4853 | switch (action) { | |
4854 | case CPU_UP_PREPARE: | |
4855 | case CPU_DOWN_PREPARE: | |
4856 | for_each_online_cpu(i) | |
4857 | cpu_attach_domain(&sched_domain_dummy, i); | |
4858 | arch_destroy_sched_domains(); | |
4859 | return NOTIFY_OK; | |
4860 | ||
4861 | case CPU_UP_CANCELED: | |
4862 | case CPU_DOWN_FAILED: | |
4863 | case CPU_ONLINE: | |
4864 | case CPU_DEAD: | |
4865 | /* | |
4866 | * Fall through and re-initialise the domains. | |
4867 | */ | |
4868 | break; | |
4869 | default: | |
4870 | return NOTIFY_DONE; | |
4871 | } | |
4872 | ||
4873 | /* The hotplug lock is already held by cpu_up/cpu_down */ | |
4874 | arch_init_sched_domains(); | |
4875 | ||
4876 | return NOTIFY_OK; | |
4877 | } | |
4878 | #endif | |
4879 | ||
4880 | void __init sched_init_smp(void) | |
4881 | { | |
4882 | lock_cpu_hotplug(); | |
4883 | arch_init_sched_domains(); | |
4884 | unlock_cpu_hotplug(); | |
4885 | /* XXX: Theoretical race here - CPU may be hotplugged now */ | |
4886 | hotcpu_notifier(update_sched_domains, 0); | |
4887 | } | |
4888 | #else | |
4889 | void __init sched_init_smp(void) | |
4890 | { | |
4891 | } | |
4892 | #endif /* CONFIG_SMP */ | |
4893 | ||
4894 | int in_sched_functions(unsigned long addr) | |
4895 | { | |
4896 | /* Linker adds these: start and end of __sched functions */ | |
4897 | extern char __sched_text_start[], __sched_text_end[]; | |
4898 | return in_lock_functions(addr) || | |
4899 | (addr >= (unsigned long)__sched_text_start | |
4900 | && addr < (unsigned long)__sched_text_end); | |
4901 | } | |
4902 | ||
4903 | void __init sched_init(void) | |
4904 | { | |
4905 | runqueue_t *rq; | |
4906 | int i, j, k; | |
4907 | ||
4908 | for (i = 0; i < NR_CPUS; i++) { | |
4909 | prio_array_t *array; | |
4910 | ||
4911 | rq = cpu_rq(i); | |
4912 | spin_lock_init(&rq->lock); | |
4913 | rq->active = rq->arrays; | |
4914 | rq->expired = rq->arrays + 1; | |
4915 | rq->best_expired_prio = MAX_PRIO; | |
4916 | ||
4917 | #ifdef CONFIG_SMP | |
4918 | rq->sd = &sched_domain_dummy; | |
4919 | rq->cpu_load = 0; | |
4920 | rq->active_balance = 0; | |
4921 | rq->push_cpu = 0; | |
4922 | rq->migration_thread = NULL; | |
4923 | INIT_LIST_HEAD(&rq->migration_queue); | |
4924 | #endif | |
4925 | atomic_set(&rq->nr_iowait, 0); | |
4926 | ||
4927 | for (j = 0; j < 2; j++) { | |
4928 | array = rq->arrays + j; | |
4929 | for (k = 0; k < MAX_PRIO; k++) { | |
4930 | INIT_LIST_HEAD(array->queue + k); | |
4931 | __clear_bit(k, array->bitmap); | |
4932 | } | |
4933 | // delimiter for bitsearch | |
4934 | __set_bit(MAX_PRIO, array->bitmap); | |
4935 | } | |
4936 | } | |
4937 | ||
4938 | /* | |
4939 | * The boot idle thread does lazy MMU switching as well: | |
4940 | */ | |
4941 | atomic_inc(&init_mm.mm_count); | |
4942 | enter_lazy_tlb(&init_mm, current); | |
4943 | ||
4944 | /* | |
4945 | * Make us the idle thread. Technically, schedule() should not be | |
4946 | * called from this thread, however somewhere below it might be, | |
4947 | * but because we are the idle thread, we just pick up running again | |
4948 | * when this runqueue becomes "idle". | |
4949 | */ | |
4950 | init_idle(current, smp_processor_id()); | |
4951 | } | |
4952 | ||
4953 | #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP | |
4954 | void __might_sleep(char *file, int line) | |
4955 | { | |
4956 | #if defined(in_atomic) | |
4957 | static unsigned long prev_jiffy; /* ratelimiting */ | |
4958 | ||
4959 | if ((in_atomic() || irqs_disabled()) && | |
4960 | system_state == SYSTEM_RUNNING && !oops_in_progress) { | |
4961 | if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) | |
4962 | return; | |
4963 | prev_jiffy = jiffies; | |
4964 | printk(KERN_ERR "Debug: sleeping function called from invalid" | |
4965 | " context at %s:%d\n", file, line); | |
4966 | printk("in_atomic():%d, irqs_disabled():%d\n", | |
4967 | in_atomic(), irqs_disabled()); | |
4968 | dump_stack(); | |
4969 | } | |
4970 | #endif | |
4971 | } | |
4972 | EXPORT_SYMBOL(__might_sleep); | |
4973 | #endif | |
4974 | ||
4975 | #ifdef CONFIG_MAGIC_SYSRQ | |
4976 | void normalize_rt_tasks(void) | |
4977 | { | |
4978 | struct task_struct *p; | |
4979 | prio_array_t *array; | |
4980 | unsigned long flags; | |
4981 | runqueue_t *rq; | |
4982 | ||
4983 | read_lock_irq(&tasklist_lock); | |
4984 | for_each_process (p) { | |
4985 | if (!rt_task(p)) | |
4986 | continue; | |
4987 | ||
4988 | rq = task_rq_lock(p, &flags); | |
4989 | ||
4990 | array = p->array; | |
4991 | if (array) | |
4992 | deactivate_task(p, task_rq(p)); | |
4993 | __setscheduler(p, SCHED_NORMAL, 0); | |
4994 | if (array) { | |
4995 | __activate_task(p, task_rq(p)); | |
4996 | resched_task(rq->curr); | |
4997 | } | |
4998 | ||
4999 | task_rq_unlock(rq, &flags); | |
5000 | } | |
5001 | read_unlock_irq(&tasklist_lock); | |
5002 | } | |
5003 | ||
5004 | #endif /* CONFIG_MAGIC_SYSRQ */ |