sched/deadline: Add SCHED_DEADLINE avg_update accounting
[deliverable/linux.git] / kernel / sched / deadline.c
CommitLineData
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1/*
2 * Deadline Scheduling Class (SCHED_DEADLINE)
3 *
4 * Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS).
5 *
6 * Tasks that periodically executes their instances for less than their
7 * runtime won't miss any of their deadlines.
8 * Tasks that are not periodic or sporadic or that tries to execute more
9 * than their reserved bandwidth will be slowed down (and may potentially
10 * miss some of their deadlines), and won't affect any other task.
11 *
12 * Copyright (C) 2012 Dario Faggioli <raistlin@linux.it>,
1baca4ce 13 * Juri Lelli <juri.lelli@gmail.com>,
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14 * Michael Trimarchi <michael@amarulasolutions.com>,
15 * Fabio Checconi <fchecconi@gmail.com>
16 */
17#include "sched.h"
18
19static inline int dl_time_before(u64 a, u64 b)
20{
21 return (s64)(a - b) < 0;
22}
23
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24/*
25 * Tells if entity @a should preempt entity @b.
26 */
27static inline
28int dl_entity_preempt(struct sched_dl_entity *a, struct sched_dl_entity *b)
29{
30 return dl_time_before(a->deadline, b->deadline);
31}
32
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33static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
34{
35 return container_of(dl_se, struct task_struct, dl);
36}
37
38static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq)
39{
40 return container_of(dl_rq, struct rq, dl);
41}
42
43static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se)
44{
45 struct task_struct *p = dl_task_of(dl_se);
46 struct rq *rq = task_rq(p);
47
48 return &rq->dl;
49}
50
51static inline int on_dl_rq(struct sched_dl_entity *dl_se)
52{
53 return !RB_EMPTY_NODE(&dl_se->rb_node);
54}
55
56static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
57{
58 struct sched_dl_entity *dl_se = &p->dl;
59
60 return dl_rq->rb_leftmost == &dl_se->rb_node;
61}
62
63void init_dl_rq(struct dl_rq *dl_rq, struct rq *rq)
64{
65 dl_rq->rb_root = RB_ROOT;
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66
67#ifdef CONFIG_SMP
68 /* zero means no -deadline tasks */
69 dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0;
70
71 dl_rq->dl_nr_migratory = 0;
72 dl_rq->overloaded = 0;
73 dl_rq->pushable_dl_tasks_root = RB_ROOT;
74#endif
75}
76
77#ifdef CONFIG_SMP
78
79static inline int dl_overloaded(struct rq *rq)
80{
81 return atomic_read(&rq->rd->dlo_count);
82}
83
84static inline void dl_set_overload(struct rq *rq)
85{
86 if (!rq->online)
87 return;
88
89 cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask);
90 /*
91 * Must be visible before the overload count is
92 * set (as in sched_rt.c).
93 *
94 * Matched by the barrier in pull_dl_task().
95 */
96 smp_wmb();
97 atomic_inc(&rq->rd->dlo_count);
98}
99
100static inline void dl_clear_overload(struct rq *rq)
101{
102 if (!rq->online)
103 return;
104
105 atomic_dec(&rq->rd->dlo_count);
106 cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask);
107}
108
109static void update_dl_migration(struct dl_rq *dl_rq)
110{
111 if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_total > 1) {
112 if (!dl_rq->overloaded) {
113 dl_set_overload(rq_of_dl_rq(dl_rq));
114 dl_rq->overloaded = 1;
115 }
116 } else if (dl_rq->overloaded) {
117 dl_clear_overload(rq_of_dl_rq(dl_rq));
118 dl_rq->overloaded = 0;
119 }
120}
121
122static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
123{
124 struct task_struct *p = dl_task_of(dl_se);
125 dl_rq = &rq_of_dl_rq(dl_rq)->dl;
126
127 dl_rq->dl_nr_total++;
128 if (p->nr_cpus_allowed > 1)
129 dl_rq->dl_nr_migratory++;
130
131 update_dl_migration(dl_rq);
132}
133
134static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
135{
136 struct task_struct *p = dl_task_of(dl_se);
137 dl_rq = &rq_of_dl_rq(dl_rq)->dl;
138
139 dl_rq->dl_nr_total--;
140 if (p->nr_cpus_allowed > 1)
141 dl_rq->dl_nr_migratory--;
142
143 update_dl_migration(dl_rq);
144}
145
146/*
147 * The list of pushable -deadline task is not a plist, like in
148 * sched_rt.c, it is an rb-tree with tasks ordered by deadline.
149 */
150static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
151{
152 struct dl_rq *dl_rq = &rq->dl;
153 struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_node;
154 struct rb_node *parent = NULL;
155 struct task_struct *entry;
156 int leftmost = 1;
157
158 BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
159
160 while (*link) {
161 parent = *link;
162 entry = rb_entry(parent, struct task_struct,
163 pushable_dl_tasks);
164 if (dl_entity_preempt(&p->dl, &entry->dl))
165 link = &parent->rb_left;
166 else {
167 link = &parent->rb_right;
168 leftmost = 0;
169 }
170 }
171
172 if (leftmost)
173 dl_rq->pushable_dl_tasks_leftmost = &p->pushable_dl_tasks;
174
175 rb_link_node(&p->pushable_dl_tasks, parent, link);
176 rb_insert_color(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
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177}
178
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179static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
180{
181 struct dl_rq *dl_rq = &rq->dl;
182
183 if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
184 return;
185
186 if (dl_rq->pushable_dl_tasks_leftmost == &p->pushable_dl_tasks) {
187 struct rb_node *next_node;
188
189 next_node = rb_next(&p->pushable_dl_tasks);
190 dl_rq->pushable_dl_tasks_leftmost = next_node;
191 }
192
193 rb_erase(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
194 RB_CLEAR_NODE(&p->pushable_dl_tasks);
195}
196
197static inline int has_pushable_dl_tasks(struct rq *rq)
198{
199 return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root);
200}
201
202static int push_dl_task(struct rq *rq);
203
204#else
205
206static inline
207void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
208{
209}
210
211static inline
212void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
213{
214}
215
216static inline
217void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
218{
219}
220
221static inline
222void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
223{
224}
225
226#endif /* CONFIG_SMP */
227
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228static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags);
229static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags);
230static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
231 int flags);
232
233/*
234 * We are being explicitly informed that a new instance is starting,
235 * and this means that:
236 * - the absolute deadline of the entity has to be placed at
237 * current time + relative deadline;
238 * - the runtime of the entity has to be set to the maximum value.
239 *
240 * The capability of specifying such event is useful whenever a -deadline
241 * entity wants to (try to!) synchronize its behaviour with the scheduler's
242 * one, and to (try to!) reconcile itself with its own scheduling
243 * parameters.
244 */
245static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se)
246{
247 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
248 struct rq *rq = rq_of_dl_rq(dl_rq);
249
250 WARN_ON(!dl_se->dl_new || dl_se->dl_throttled);
251
252 /*
253 * We use the regular wall clock time to set deadlines in the
254 * future; in fact, we must consider execution overheads (time
255 * spent on hardirq context, etc.).
256 */
257 dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline;
258 dl_se->runtime = dl_se->dl_runtime;
259 dl_se->dl_new = 0;
260}
261
262/*
263 * Pure Earliest Deadline First (EDF) scheduling does not deal with the
264 * possibility of a entity lasting more than what it declared, and thus
265 * exhausting its runtime.
266 *
267 * Here we are interested in making runtime overrun possible, but we do
268 * not want a entity which is misbehaving to affect the scheduling of all
269 * other entities.
270 * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
271 * is used, in order to confine each entity within its own bandwidth.
272 *
273 * This function deals exactly with that, and ensures that when the runtime
274 * of a entity is replenished, its deadline is also postponed. That ensures
275 * the overrunning entity can't interfere with other entity in the system and
276 * can't make them miss their deadlines. Reasons why this kind of overruns
277 * could happen are, typically, a entity voluntarily trying to overcome its
278 * runtime, or it just underestimated it during sched_setscheduler_ex().
279 */
280static void replenish_dl_entity(struct sched_dl_entity *dl_se)
281{
282 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
283 struct rq *rq = rq_of_dl_rq(dl_rq);
284
285 /*
286 * We keep moving the deadline away until we get some
287 * available runtime for the entity. This ensures correct
288 * handling of situations where the runtime overrun is
289 * arbitrary large.
290 */
291 while (dl_se->runtime <= 0) {
292 dl_se->deadline += dl_se->dl_deadline;
293 dl_se->runtime += dl_se->dl_runtime;
294 }
295
296 /*
297 * At this point, the deadline really should be "in
298 * the future" with respect to rq->clock. If it's
299 * not, we are, for some reason, lagging too much!
300 * Anyway, after having warn userspace abut that,
301 * we still try to keep the things running by
302 * resetting the deadline and the budget of the
303 * entity.
304 */
305 if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
306 static bool lag_once = false;
307
308 if (!lag_once) {
309 lag_once = true;
310 printk_sched("sched: DL replenish lagged to much\n");
311 }
312 dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline;
313 dl_se->runtime = dl_se->dl_runtime;
314 }
315}
316
317/*
318 * Here we check if --at time t-- an entity (which is probably being
319 * [re]activated or, in general, enqueued) can use its remaining runtime
320 * and its current deadline _without_ exceeding the bandwidth it is
321 * assigned (function returns true if it can't). We are in fact applying
322 * one of the CBS rules: when a task wakes up, if the residual runtime
323 * over residual deadline fits within the allocated bandwidth, then we
324 * can keep the current (absolute) deadline and residual budget without
325 * disrupting the schedulability of the system. Otherwise, we should
326 * refill the runtime and set the deadline a period in the future,
327 * because keeping the current (absolute) deadline of the task would
328 * result in breaking guarantees promised to other tasks.
329 *
330 * This function returns true if:
331 *
332 * runtime / (deadline - t) > dl_runtime / dl_deadline ,
333 *
334 * IOW we can't recycle current parameters.
335 */
336static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t)
337{
338 u64 left, right;
339
340 /*
341 * left and right are the two sides of the equation above,
342 * after a bit of shuffling to use multiplications instead
343 * of divisions.
344 *
345 * Note that none of the time values involved in the two
346 * multiplications are absolute: dl_deadline and dl_runtime
347 * are the relative deadline and the maximum runtime of each
348 * instance, runtime is the runtime left for the last instance
349 * and (deadline - t), since t is rq->clock, is the time left
350 * to the (absolute) deadline. Even if overflowing the u64 type
351 * is very unlikely to occur in both cases, here we scale down
352 * as we want to avoid that risk at all. Scaling down by 10
353 * means that we reduce granularity to 1us. We are fine with it,
354 * since this is only a true/false check and, anyway, thinking
355 * of anything below microseconds resolution is actually fiction
356 * (but still we want to give the user that illusion >;).
357 */
358 left = (dl_se->dl_deadline >> 10) * (dl_se->runtime >> 10);
359 right = ((dl_se->deadline - t) >> 10) * (dl_se->dl_runtime >> 10);
360
361 return dl_time_before(right, left);
362}
363
364/*
365 * When a -deadline entity is queued back on the runqueue, its runtime and
366 * deadline might need updating.
367 *
368 * The policy here is that we update the deadline of the entity only if:
369 * - the current deadline is in the past,
370 * - using the remaining runtime with the current deadline would make
371 * the entity exceed its bandwidth.
372 */
373static void update_dl_entity(struct sched_dl_entity *dl_se)
374{
375 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
376 struct rq *rq = rq_of_dl_rq(dl_rq);
377
378 /*
379 * The arrival of a new instance needs special treatment, i.e.,
380 * the actual scheduling parameters have to be "renewed".
381 */
382 if (dl_se->dl_new) {
383 setup_new_dl_entity(dl_se);
384 return;
385 }
386
387 if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
388 dl_entity_overflow(dl_se, rq_clock(rq))) {
389 dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline;
390 dl_se->runtime = dl_se->dl_runtime;
391 }
392}
393
394/*
395 * If the entity depleted all its runtime, and if we want it to sleep
396 * while waiting for some new execution time to become available, we
397 * set the bandwidth enforcement timer to the replenishment instant
398 * and try to activate it.
399 *
400 * Notice that it is important for the caller to know if the timer
401 * actually started or not (i.e., the replenishment instant is in
402 * the future or in the past).
403 */
404static int start_dl_timer(struct sched_dl_entity *dl_se)
405{
406 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
407 struct rq *rq = rq_of_dl_rq(dl_rq);
408 ktime_t now, act;
409 ktime_t soft, hard;
410 unsigned long range;
411 s64 delta;
412
413 /*
414 * We want the timer to fire at the deadline, but considering
415 * that it is actually coming from rq->clock and not from
416 * hrtimer's time base reading.
417 */
418 act = ns_to_ktime(dl_se->deadline);
419 now = hrtimer_cb_get_time(&dl_se->dl_timer);
420 delta = ktime_to_ns(now) - rq_clock(rq);
421 act = ktime_add_ns(act, delta);
422
423 /*
424 * If the expiry time already passed, e.g., because the value
425 * chosen as the deadline is too small, don't even try to
426 * start the timer in the past!
427 */
428 if (ktime_us_delta(act, now) < 0)
429 return 0;
430
431 hrtimer_set_expires(&dl_se->dl_timer, act);
432
433 soft = hrtimer_get_softexpires(&dl_se->dl_timer);
434 hard = hrtimer_get_expires(&dl_se->dl_timer);
435 range = ktime_to_ns(ktime_sub(hard, soft));
436 __hrtimer_start_range_ns(&dl_se->dl_timer, soft,
437 range, HRTIMER_MODE_ABS, 0);
438
439 return hrtimer_active(&dl_se->dl_timer);
440}
441
442/*
443 * This is the bandwidth enforcement timer callback. If here, we know
444 * a task is not on its dl_rq, since the fact that the timer was running
445 * means the task is throttled and needs a runtime replenishment.
446 *
447 * However, what we actually do depends on the fact the task is active,
448 * (it is on its rq) or has been removed from there by a call to
449 * dequeue_task_dl(). In the former case we must issue the runtime
450 * replenishment and add the task back to the dl_rq; in the latter, we just
451 * do nothing but clearing dl_throttled, so that runtime and deadline
452 * updating (and the queueing back to dl_rq) will be done by the
453 * next call to enqueue_task_dl().
454 */
455static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
456{
457 struct sched_dl_entity *dl_se = container_of(timer,
458 struct sched_dl_entity,
459 dl_timer);
460 struct task_struct *p = dl_task_of(dl_se);
461 struct rq *rq = task_rq(p);
462 raw_spin_lock(&rq->lock);
463
464 /*
465 * We need to take care of a possible races here. In fact, the
466 * task might have changed its scheduling policy to something
467 * different from SCHED_DEADLINE or changed its reservation
468 * parameters (through sched_setscheduler()).
469 */
470 if (!dl_task(p) || dl_se->dl_new)
471 goto unlock;
472
473 sched_clock_tick();
474 update_rq_clock(rq);
475 dl_se->dl_throttled = 0;
476 if (p->on_rq) {
477 enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
478 if (task_has_dl_policy(rq->curr))
479 check_preempt_curr_dl(rq, p, 0);
480 else
481 resched_task(rq->curr);
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482#ifdef CONFIG_SMP
483 /*
484 * Queueing this task back might have overloaded rq,
485 * check if we need to kick someone away.
486 */
487 if (has_pushable_dl_tasks(rq))
488 push_dl_task(rq);
489#endif
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490 }
491unlock:
492 raw_spin_unlock(&rq->lock);
493
494 return HRTIMER_NORESTART;
495}
496
497void init_dl_task_timer(struct sched_dl_entity *dl_se)
498{
499 struct hrtimer *timer = &dl_se->dl_timer;
500
501 if (hrtimer_active(timer)) {
502 hrtimer_try_to_cancel(timer);
503 return;
504 }
505
506 hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
507 timer->function = dl_task_timer;
508}
509
510static
511int dl_runtime_exceeded(struct rq *rq, struct sched_dl_entity *dl_se)
512{
513 int dmiss = dl_time_before(dl_se->deadline, rq_clock(rq));
514 int rorun = dl_se->runtime <= 0;
515
516 if (!rorun && !dmiss)
517 return 0;
518
519 /*
520 * If we are beyond our current deadline and we are still
521 * executing, then we have already used some of the runtime of
522 * the next instance. Thus, if we do not account that, we are
523 * stealing bandwidth from the system at each deadline miss!
524 */
525 if (dmiss) {
526 dl_se->runtime = rorun ? dl_se->runtime : 0;
527 dl_se->runtime -= rq_clock(rq) - dl_se->deadline;
528 }
529
530 return 1;
531}
532
533/*
534 * Update the current task's runtime statistics (provided it is still
535 * a -deadline task and has not been removed from the dl_rq).
536 */
537static void update_curr_dl(struct rq *rq)
538{
539 struct task_struct *curr = rq->curr;
540 struct sched_dl_entity *dl_se = &curr->dl;
541 u64 delta_exec;
542
543 if (!dl_task(curr) || !on_dl_rq(dl_se))
544 return;
545
546 /*
547 * Consumed budget is computed considering the time as
548 * observed by schedulable tasks (excluding time spent
549 * in hardirq context, etc.). Deadlines are instead
550 * computed using hard walltime. This seems to be the more
551 * natural solution, but the full ramifications of this
552 * approach need further study.
553 */
554 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
555 if (unlikely((s64)delta_exec < 0))
556 delta_exec = 0;
557
558 schedstat_set(curr->se.statistics.exec_max,
559 max(curr->se.statistics.exec_max, delta_exec));
560
561 curr->se.sum_exec_runtime += delta_exec;
562 account_group_exec_runtime(curr, delta_exec);
563
564 curr->se.exec_start = rq_clock_task(rq);
565 cpuacct_charge(curr, delta_exec);
566
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567 sched_rt_avg_update(rq, delta_exec);
568
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569 dl_se->runtime -= delta_exec;
570 if (dl_runtime_exceeded(rq, dl_se)) {
571 __dequeue_task_dl(rq, curr, 0);
572 if (likely(start_dl_timer(dl_se)))
573 dl_se->dl_throttled = 1;
574 else
575 enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
576
577 if (!is_leftmost(curr, &rq->dl))
578 resched_task(curr);
579 }
580}
581
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582#ifdef CONFIG_SMP
583
584static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu);
585
586static inline u64 next_deadline(struct rq *rq)
587{
588 struct task_struct *next = pick_next_earliest_dl_task(rq, rq->cpu);
589
590 if (next && dl_prio(next->prio))
591 return next->dl.deadline;
592 else
593 return 0;
594}
595
596static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
597{
598 struct rq *rq = rq_of_dl_rq(dl_rq);
599
600 if (dl_rq->earliest_dl.curr == 0 ||
601 dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
602 /*
603 * If the dl_rq had no -deadline tasks, or if the new task
604 * has shorter deadline than the current one on dl_rq, we
605 * know that the previous earliest becomes our next earliest,
606 * as the new task becomes the earliest itself.
607 */
608 dl_rq->earliest_dl.next = dl_rq->earliest_dl.curr;
609 dl_rq->earliest_dl.curr = deadline;
610 } else if (dl_rq->earliest_dl.next == 0 ||
611 dl_time_before(deadline, dl_rq->earliest_dl.next)) {
612 /*
613 * On the other hand, if the new -deadline task has a
614 * a later deadline than the earliest one on dl_rq, but
615 * it is earlier than the next (if any), we must
616 * recompute the next-earliest.
617 */
618 dl_rq->earliest_dl.next = next_deadline(rq);
619 }
620}
621
622static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
623{
624 struct rq *rq = rq_of_dl_rq(dl_rq);
625
626 /*
627 * Since we may have removed our earliest (and/or next earliest)
628 * task we must recompute them.
629 */
630 if (!dl_rq->dl_nr_running) {
631 dl_rq->earliest_dl.curr = 0;
632 dl_rq->earliest_dl.next = 0;
633 } else {
634 struct rb_node *leftmost = dl_rq->rb_leftmost;
635 struct sched_dl_entity *entry;
636
637 entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
638 dl_rq->earliest_dl.curr = entry->deadline;
639 dl_rq->earliest_dl.next = next_deadline(rq);
640 }
641}
642
643#else
644
645static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
646static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
647
648#endif /* CONFIG_SMP */
649
650static inline
651void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
652{
653 int prio = dl_task_of(dl_se)->prio;
654 u64 deadline = dl_se->deadline;
655
656 WARN_ON(!dl_prio(prio));
657 dl_rq->dl_nr_running++;
658
659 inc_dl_deadline(dl_rq, deadline);
660 inc_dl_migration(dl_se, dl_rq);
661}
662
663static inline
664void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
665{
666 int prio = dl_task_of(dl_se)->prio;
667
668 WARN_ON(!dl_prio(prio));
669 WARN_ON(!dl_rq->dl_nr_running);
670 dl_rq->dl_nr_running--;
671
672 dec_dl_deadline(dl_rq, dl_se->deadline);
673 dec_dl_migration(dl_se, dl_rq);
674}
675
aab03e05
DF
676static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
677{
678 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
679 struct rb_node **link = &dl_rq->rb_root.rb_node;
680 struct rb_node *parent = NULL;
681 struct sched_dl_entity *entry;
682 int leftmost = 1;
683
684 BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
685
686 while (*link) {
687 parent = *link;
688 entry = rb_entry(parent, struct sched_dl_entity, rb_node);
689 if (dl_time_before(dl_se->deadline, entry->deadline))
690 link = &parent->rb_left;
691 else {
692 link = &parent->rb_right;
693 leftmost = 0;
694 }
695 }
696
697 if (leftmost)
698 dl_rq->rb_leftmost = &dl_se->rb_node;
699
700 rb_link_node(&dl_se->rb_node, parent, link);
701 rb_insert_color(&dl_se->rb_node, &dl_rq->rb_root);
702
1baca4ce 703 inc_dl_tasks(dl_se, dl_rq);
aab03e05
DF
704}
705
706static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
707{
708 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
709
710 if (RB_EMPTY_NODE(&dl_se->rb_node))
711 return;
712
713 if (dl_rq->rb_leftmost == &dl_se->rb_node) {
714 struct rb_node *next_node;
715
716 next_node = rb_next(&dl_se->rb_node);
717 dl_rq->rb_leftmost = next_node;
718 }
719
720 rb_erase(&dl_se->rb_node, &dl_rq->rb_root);
721 RB_CLEAR_NODE(&dl_se->rb_node);
722
1baca4ce 723 dec_dl_tasks(dl_se, dl_rq);
aab03e05
DF
724}
725
726static void
727enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags)
728{
729 BUG_ON(on_dl_rq(dl_se));
730
731 /*
732 * If this is a wakeup or a new instance, the scheduling
733 * parameters of the task might need updating. Otherwise,
734 * we want a replenishment of its runtime.
735 */
736 if (!dl_se->dl_new && flags & ENQUEUE_REPLENISH)
737 replenish_dl_entity(dl_se);
738 else
739 update_dl_entity(dl_se);
740
741 __enqueue_dl_entity(dl_se);
742}
743
744static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
745{
746 __dequeue_dl_entity(dl_se);
747}
748
749static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
750{
751 /*
752 * If p is throttled, we do nothing. In fact, if it exhausted
753 * its budget it needs a replenishment and, since it now is on
754 * its rq, the bandwidth timer callback (which clearly has not
755 * run yet) will take care of this.
756 */
757 if (p->dl.dl_throttled)
758 return;
759
760 enqueue_dl_entity(&p->dl, flags);
1baca4ce
JL
761
762 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
763 enqueue_pushable_dl_task(rq, p);
764
aab03e05
DF
765 inc_nr_running(rq);
766}
767
768static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
769{
770 dequeue_dl_entity(&p->dl);
1baca4ce 771 dequeue_pushable_dl_task(rq, p);
aab03e05
DF
772}
773
774static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
775{
776 update_curr_dl(rq);
777 __dequeue_task_dl(rq, p, flags);
778
779 dec_nr_running(rq);
780}
781
782/*
783 * Yield task semantic for -deadline tasks is:
784 *
785 * get off from the CPU until our next instance, with
786 * a new runtime. This is of little use now, since we
787 * don't have a bandwidth reclaiming mechanism. Anyway,
788 * bandwidth reclaiming is planned for the future, and
789 * yield_task_dl will indicate that some spare budget
790 * is available for other task instances to use it.
791 */
792static void yield_task_dl(struct rq *rq)
793{
794 struct task_struct *p = rq->curr;
795
796 /*
797 * We make the task go to sleep until its current deadline by
798 * forcing its runtime to zero. This way, update_curr_dl() stops
799 * it and the bandwidth timer will wake it up and will give it
800 * new scheduling parameters (thanks to dl_new=1).
801 */
802 if (p->dl.runtime > 0) {
803 rq->curr->dl.dl_new = 1;
804 p->dl.runtime = 0;
805 }
806 update_curr_dl(rq);
807}
808
1baca4ce
JL
809#ifdef CONFIG_SMP
810
811static int find_later_rq(struct task_struct *task);
812static int latest_cpu_find(struct cpumask *span,
813 struct task_struct *task,
814 struct cpumask *later_mask);
815
816static int
817select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
818{
819 struct task_struct *curr;
820 struct rq *rq;
821
822 if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
823 goto out;
824
825 rq = cpu_rq(cpu);
826
827 rcu_read_lock();
828 curr = ACCESS_ONCE(rq->curr); /* unlocked access */
829
830 /*
831 * If we are dealing with a -deadline task, we must
832 * decide where to wake it up.
833 * If it has a later deadline and the current task
834 * on this rq can't move (provided the waking task
835 * can!) we prefer to send it somewhere else. On the
836 * other hand, if it has a shorter deadline, we
837 * try to make it stay here, it might be important.
838 */
839 if (unlikely(dl_task(curr)) &&
840 (curr->nr_cpus_allowed < 2 ||
841 !dl_entity_preempt(&p->dl, &curr->dl)) &&
842 (p->nr_cpus_allowed > 1)) {
843 int target = find_later_rq(p);
844
845 if (target != -1)
846 cpu = target;
847 }
848 rcu_read_unlock();
849
850out:
851 return cpu;
852}
853
854static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
855{
856 /*
857 * Current can't be migrated, useless to reschedule,
858 * let's hope p can move out.
859 */
860 if (rq->curr->nr_cpus_allowed == 1 ||
861 latest_cpu_find(rq->rd->span, rq->curr, NULL) == -1)
862 return;
863
864 /*
865 * p is migratable, so let's not schedule it and
866 * see if it is pushed or pulled somewhere else.
867 */
868 if (p->nr_cpus_allowed != 1 &&
869 latest_cpu_find(rq->rd->span, p, NULL) != -1)
870 return;
871
872 resched_task(rq->curr);
873}
874
875#endif /* CONFIG_SMP */
876
aab03e05
DF
877/*
878 * Only called when both the current and waking task are -deadline
879 * tasks.
880 */
881static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
882 int flags)
883{
1baca4ce 884 if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
aab03e05 885 resched_task(rq->curr);
1baca4ce
JL
886 return;
887 }
888
889#ifdef CONFIG_SMP
890 /*
891 * In the unlikely case current and p have the same deadline
892 * let us try to decide what's the best thing to do...
893 */
894 if ((s64)(p->dl.deadline - rq->curr->dl.deadline) == 0 &&
895 !need_resched())
896 check_preempt_equal_dl(rq, p);
897#endif /* CONFIG_SMP */
aab03e05
DF
898}
899
900#ifdef CONFIG_SCHED_HRTICK
901static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
902{
903 s64 delta = p->dl.dl_runtime - p->dl.runtime;
904
905 if (delta > 10000)
906 hrtick_start(rq, p->dl.runtime);
907}
908#endif
909
910static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
911 struct dl_rq *dl_rq)
912{
913 struct rb_node *left = dl_rq->rb_leftmost;
914
915 if (!left)
916 return NULL;
917
918 return rb_entry(left, struct sched_dl_entity, rb_node);
919}
920
921struct task_struct *pick_next_task_dl(struct rq *rq)
922{
923 struct sched_dl_entity *dl_se;
924 struct task_struct *p;
925 struct dl_rq *dl_rq;
926
927 dl_rq = &rq->dl;
928
929 if (unlikely(!dl_rq->dl_nr_running))
930 return NULL;
931
932 dl_se = pick_next_dl_entity(rq, dl_rq);
933 BUG_ON(!dl_se);
934
935 p = dl_task_of(dl_se);
936 p->se.exec_start = rq_clock_task(rq);
1baca4ce
JL
937
938 /* Running task will never be pushed. */
939 if (p)
940 dequeue_pushable_dl_task(rq, p);
941
aab03e05
DF
942#ifdef CONFIG_SCHED_HRTICK
943 if (hrtick_enabled(rq))
944 start_hrtick_dl(rq, p);
945#endif
1baca4ce
JL
946
947#ifdef CONFIG_SMP
948 rq->post_schedule = has_pushable_dl_tasks(rq);
949#endif /* CONFIG_SMP */
950
aab03e05
DF
951 return p;
952}
953
954static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
955{
956 update_curr_dl(rq);
1baca4ce
JL
957
958 if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
959 enqueue_pushable_dl_task(rq, p);
aab03e05
DF
960}
961
962static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
963{
964 update_curr_dl(rq);
965
966#ifdef CONFIG_SCHED_HRTICK
967 if (hrtick_enabled(rq) && queued && p->dl.runtime > 0)
968 start_hrtick_dl(rq, p);
969#endif
970}
971
972static void task_fork_dl(struct task_struct *p)
973{
974 /*
975 * SCHED_DEADLINE tasks cannot fork and this is achieved through
976 * sched_fork()
977 */
978}
979
980static void task_dead_dl(struct task_struct *p)
981{
982 struct hrtimer *timer = &p->dl.dl_timer;
983
984 if (hrtimer_active(timer))
985 hrtimer_try_to_cancel(timer);
986}
987
988static void set_curr_task_dl(struct rq *rq)
989{
990 struct task_struct *p = rq->curr;
991
992 p->se.exec_start = rq_clock_task(rq);
1baca4ce
JL
993
994 /* You can't push away the running task */
995 dequeue_pushable_dl_task(rq, p);
996}
997
998#ifdef CONFIG_SMP
999
1000/* Only try algorithms three times */
1001#define DL_MAX_TRIES 3
1002
1003static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
1004{
1005 if (!task_running(rq, p) &&
1006 (cpu < 0 || cpumask_test_cpu(cpu, &p->cpus_allowed)) &&
1007 (p->nr_cpus_allowed > 1))
1008 return 1;
1009
1010 return 0;
1011}
1012
1013/* Returns the second earliest -deadline task, NULL otherwise */
1014static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu)
1015{
1016 struct rb_node *next_node = rq->dl.rb_leftmost;
1017 struct sched_dl_entity *dl_se;
1018 struct task_struct *p = NULL;
1019
1020next_node:
1021 next_node = rb_next(next_node);
1022 if (next_node) {
1023 dl_se = rb_entry(next_node, struct sched_dl_entity, rb_node);
1024 p = dl_task_of(dl_se);
1025
1026 if (pick_dl_task(rq, p, cpu))
1027 return p;
1028
1029 goto next_node;
1030 }
1031
1032 return NULL;
1033}
1034
1035static int latest_cpu_find(struct cpumask *span,
1036 struct task_struct *task,
1037 struct cpumask *later_mask)
1038{
1039 const struct sched_dl_entity *dl_se = &task->dl;
1040 int cpu, found = -1, best = 0;
1041 u64 max_dl = 0;
1042
1043 for_each_cpu(cpu, span) {
1044 struct rq *rq = cpu_rq(cpu);
1045 struct dl_rq *dl_rq = &rq->dl;
1046
1047 if (cpumask_test_cpu(cpu, &task->cpus_allowed) &&
1048 (!dl_rq->dl_nr_running || dl_time_before(dl_se->deadline,
1049 dl_rq->earliest_dl.curr))) {
1050 if (later_mask)
1051 cpumask_set_cpu(cpu, later_mask);
1052 if (!best && !dl_rq->dl_nr_running) {
1053 best = 1;
1054 found = cpu;
1055 } else if (!best &&
1056 dl_time_before(max_dl,
1057 dl_rq->earliest_dl.curr)) {
1058 max_dl = dl_rq->earliest_dl.curr;
1059 found = cpu;
1060 }
1061 } else if (later_mask)
1062 cpumask_clear_cpu(cpu, later_mask);
1063 }
1064
1065 return found;
1066}
1067
1068static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
1069
1070static int find_later_rq(struct task_struct *task)
1071{
1072 struct sched_domain *sd;
1073 struct cpumask *later_mask = __get_cpu_var(local_cpu_mask_dl);
1074 int this_cpu = smp_processor_id();
1075 int best_cpu, cpu = task_cpu(task);
1076
1077 /* Make sure the mask is initialized first */
1078 if (unlikely(!later_mask))
1079 return -1;
1080
1081 if (task->nr_cpus_allowed == 1)
1082 return -1;
1083
1084 best_cpu = latest_cpu_find(task_rq(task)->rd->span, task, later_mask);
1085 if (best_cpu == -1)
1086 return -1;
1087
1088 /*
1089 * If we are here, some target has been found,
1090 * the most suitable of which is cached in best_cpu.
1091 * This is, among the runqueues where the current tasks
1092 * have later deadlines than the task's one, the rq
1093 * with the latest possible one.
1094 *
1095 * Now we check how well this matches with task's
1096 * affinity and system topology.
1097 *
1098 * The last cpu where the task run is our first
1099 * guess, since it is most likely cache-hot there.
1100 */
1101 if (cpumask_test_cpu(cpu, later_mask))
1102 return cpu;
1103 /*
1104 * Check if this_cpu is to be skipped (i.e., it is
1105 * not in the mask) or not.
1106 */
1107 if (!cpumask_test_cpu(this_cpu, later_mask))
1108 this_cpu = -1;
1109
1110 rcu_read_lock();
1111 for_each_domain(cpu, sd) {
1112 if (sd->flags & SD_WAKE_AFFINE) {
1113
1114 /*
1115 * If possible, preempting this_cpu is
1116 * cheaper than migrating.
1117 */
1118 if (this_cpu != -1 &&
1119 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1120 rcu_read_unlock();
1121 return this_cpu;
1122 }
1123
1124 /*
1125 * Last chance: if best_cpu is valid and is
1126 * in the mask, that becomes our choice.
1127 */
1128 if (best_cpu < nr_cpu_ids &&
1129 cpumask_test_cpu(best_cpu, sched_domain_span(sd))) {
1130 rcu_read_unlock();
1131 return best_cpu;
1132 }
1133 }
1134 }
1135 rcu_read_unlock();
1136
1137 /*
1138 * At this point, all our guesses failed, we just return
1139 * 'something', and let the caller sort the things out.
1140 */
1141 if (this_cpu != -1)
1142 return this_cpu;
1143
1144 cpu = cpumask_any(later_mask);
1145 if (cpu < nr_cpu_ids)
1146 return cpu;
1147
1148 return -1;
1149}
1150
1151/* Locks the rq it finds */
1152static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
1153{
1154 struct rq *later_rq = NULL;
1155 int tries;
1156 int cpu;
1157
1158 for (tries = 0; tries < DL_MAX_TRIES; tries++) {
1159 cpu = find_later_rq(task);
1160
1161 if ((cpu == -1) || (cpu == rq->cpu))
1162 break;
1163
1164 later_rq = cpu_rq(cpu);
1165
1166 /* Retry if something changed. */
1167 if (double_lock_balance(rq, later_rq)) {
1168 if (unlikely(task_rq(task) != rq ||
1169 !cpumask_test_cpu(later_rq->cpu,
1170 &task->cpus_allowed) ||
1171 task_running(rq, task) || !task->on_rq)) {
1172 double_unlock_balance(rq, later_rq);
1173 later_rq = NULL;
1174 break;
1175 }
1176 }
1177
1178 /*
1179 * If the rq we found has no -deadline task, or
1180 * its earliest one has a later deadline than our
1181 * task, the rq is a good one.
1182 */
1183 if (!later_rq->dl.dl_nr_running ||
1184 dl_time_before(task->dl.deadline,
1185 later_rq->dl.earliest_dl.curr))
1186 break;
1187
1188 /* Otherwise we try again. */
1189 double_unlock_balance(rq, later_rq);
1190 later_rq = NULL;
1191 }
1192
1193 return later_rq;
1194}
1195
1196static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
1197{
1198 struct task_struct *p;
1199
1200 if (!has_pushable_dl_tasks(rq))
1201 return NULL;
1202
1203 p = rb_entry(rq->dl.pushable_dl_tasks_leftmost,
1204 struct task_struct, pushable_dl_tasks);
1205
1206 BUG_ON(rq->cpu != task_cpu(p));
1207 BUG_ON(task_current(rq, p));
1208 BUG_ON(p->nr_cpus_allowed <= 1);
1209
1210 BUG_ON(!p->se.on_rq);
1211 BUG_ON(!dl_task(p));
1212
1213 return p;
1214}
1215
1216/*
1217 * See if the non running -deadline tasks on this rq
1218 * can be sent to some other CPU where they can preempt
1219 * and start executing.
1220 */
1221static int push_dl_task(struct rq *rq)
1222{
1223 struct task_struct *next_task;
1224 struct rq *later_rq;
1225
1226 if (!rq->dl.overloaded)
1227 return 0;
1228
1229 next_task = pick_next_pushable_dl_task(rq);
1230 if (!next_task)
1231 return 0;
1232
1233retry:
1234 if (unlikely(next_task == rq->curr)) {
1235 WARN_ON(1);
1236 return 0;
1237 }
1238
1239 /*
1240 * If next_task preempts rq->curr, and rq->curr
1241 * can move away, it makes sense to just reschedule
1242 * without going further in pushing next_task.
1243 */
1244 if (dl_task(rq->curr) &&
1245 dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
1246 rq->curr->nr_cpus_allowed > 1) {
1247 resched_task(rq->curr);
1248 return 0;
1249 }
1250
1251 /* We might release rq lock */
1252 get_task_struct(next_task);
1253
1254 /* Will lock the rq it'll find */
1255 later_rq = find_lock_later_rq(next_task, rq);
1256 if (!later_rq) {
1257 struct task_struct *task;
1258
1259 /*
1260 * We must check all this again, since
1261 * find_lock_later_rq releases rq->lock and it is
1262 * then possible that next_task has migrated.
1263 */
1264 task = pick_next_pushable_dl_task(rq);
1265 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1266 /*
1267 * The task is still there. We don't try
1268 * again, some other cpu will pull it when ready.
1269 */
1270 dequeue_pushable_dl_task(rq, next_task);
1271 goto out;
1272 }
1273
1274 if (!task)
1275 /* No more tasks */
1276 goto out;
1277
1278 put_task_struct(next_task);
1279 next_task = task;
1280 goto retry;
1281 }
1282
1283 deactivate_task(rq, next_task, 0);
1284 set_task_cpu(next_task, later_rq->cpu);
1285 activate_task(later_rq, next_task, 0);
1286
1287 resched_task(later_rq->curr);
1288
1289 double_unlock_balance(rq, later_rq);
1290
1291out:
1292 put_task_struct(next_task);
1293
1294 return 1;
1295}
1296
1297static void push_dl_tasks(struct rq *rq)
1298{
1299 /* Terminates as it moves a -deadline task */
1300 while (push_dl_task(rq))
1301 ;
aab03e05
DF
1302}
1303
1baca4ce
JL
1304static int pull_dl_task(struct rq *this_rq)
1305{
1306 int this_cpu = this_rq->cpu, ret = 0, cpu;
1307 struct task_struct *p;
1308 struct rq *src_rq;
1309 u64 dmin = LONG_MAX;
1310
1311 if (likely(!dl_overloaded(this_rq)))
1312 return 0;
1313
1314 /*
1315 * Match the barrier from dl_set_overloaded; this guarantees that if we
1316 * see overloaded we must also see the dlo_mask bit.
1317 */
1318 smp_rmb();
1319
1320 for_each_cpu(cpu, this_rq->rd->dlo_mask) {
1321 if (this_cpu == cpu)
1322 continue;
1323
1324 src_rq = cpu_rq(cpu);
1325
1326 /*
1327 * It looks racy, abd it is! However, as in sched_rt.c,
1328 * we are fine with this.
1329 */
1330 if (this_rq->dl.dl_nr_running &&
1331 dl_time_before(this_rq->dl.earliest_dl.curr,
1332 src_rq->dl.earliest_dl.next))
1333 continue;
1334
1335 /* Might drop this_rq->lock */
1336 double_lock_balance(this_rq, src_rq);
1337
1338 /*
1339 * If there are no more pullable tasks on the
1340 * rq, we're done with it.
1341 */
1342 if (src_rq->dl.dl_nr_running <= 1)
1343 goto skip;
1344
1345 p = pick_next_earliest_dl_task(src_rq, this_cpu);
1346
1347 /*
1348 * We found a task to be pulled if:
1349 * - it preempts our current (if there's one),
1350 * - it will preempt the last one we pulled (if any).
1351 */
1352 if (p && dl_time_before(p->dl.deadline, dmin) &&
1353 (!this_rq->dl.dl_nr_running ||
1354 dl_time_before(p->dl.deadline,
1355 this_rq->dl.earliest_dl.curr))) {
1356 WARN_ON(p == src_rq->curr);
1357 WARN_ON(!p->se.on_rq);
1358
1359 /*
1360 * Then we pull iff p has actually an earlier
1361 * deadline than the current task of its runqueue.
1362 */
1363 if (dl_time_before(p->dl.deadline,
1364 src_rq->curr->dl.deadline))
1365 goto skip;
1366
1367 ret = 1;
1368
1369 deactivate_task(src_rq, p, 0);
1370 set_task_cpu(p, this_cpu);
1371 activate_task(this_rq, p, 0);
1372 dmin = p->dl.deadline;
1373
1374 /* Is there any other task even earlier? */
1375 }
1376skip:
1377 double_unlock_balance(this_rq, src_rq);
1378 }
1379
1380 return ret;
1381}
1382
1383static void pre_schedule_dl(struct rq *rq, struct task_struct *prev)
1384{
1385 /* Try to pull other tasks here */
1386 if (dl_task(prev))
1387 pull_dl_task(rq);
1388}
1389
1390static void post_schedule_dl(struct rq *rq)
1391{
1392 push_dl_tasks(rq);
1393}
1394
1395/*
1396 * Since the task is not running and a reschedule is not going to happen
1397 * anytime soon on its runqueue, we try pushing it away now.
1398 */
1399static void task_woken_dl(struct rq *rq, struct task_struct *p)
1400{
1401 if (!task_running(rq, p) &&
1402 !test_tsk_need_resched(rq->curr) &&
1403 has_pushable_dl_tasks(rq) &&
1404 p->nr_cpus_allowed > 1 &&
1405 dl_task(rq->curr) &&
1406 (rq->curr->nr_cpus_allowed < 2 ||
1407 dl_entity_preempt(&rq->curr->dl, &p->dl))) {
1408 push_dl_tasks(rq);
1409 }
1410}
1411
1412static void set_cpus_allowed_dl(struct task_struct *p,
1413 const struct cpumask *new_mask)
1414{
1415 struct rq *rq;
1416 int weight;
1417
1418 BUG_ON(!dl_task(p));
1419
1420 /*
1421 * Update only if the task is actually running (i.e.,
1422 * it is on the rq AND it is not throttled).
1423 */
1424 if (!on_dl_rq(&p->dl))
1425 return;
1426
1427 weight = cpumask_weight(new_mask);
1428
1429 /*
1430 * Only update if the process changes its state from whether it
1431 * can migrate or not.
1432 */
1433 if ((p->nr_cpus_allowed > 1) == (weight > 1))
1434 return;
1435
1436 rq = task_rq(p);
1437
1438 /*
1439 * The process used to be able to migrate OR it can now migrate
1440 */
1441 if (weight <= 1) {
1442 if (!task_current(rq, p))
1443 dequeue_pushable_dl_task(rq, p);
1444 BUG_ON(!rq->dl.dl_nr_migratory);
1445 rq->dl.dl_nr_migratory--;
1446 } else {
1447 if (!task_current(rq, p))
1448 enqueue_pushable_dl_task(rq, p);
1449 rq->dl.dl_nr_migratory++;
1450 }
1451
1452 update_dl_migration(&rq->dl);
1453}
1454
1455/* Assumes rq->lock is held */
1456static void rq_online_dl(struct rq *rq)
1457{
1458 if (rq->dl.overloaded)
1459 dl_set_overload(rq);
1460}
1461
1462/* Assumes rq->lock is held */
1463static void rq_offline_dl(struct rq *rq)
1464{
1465 if (rq->dl.overloaded)
1466 dl_clear_overload(rq);
1467}
1468
1469void init_sched_dl_class(void)
1470{
1471 unsigned int i;
1472
1473 for_each_possible_cpu(i)
1474 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
1475 GFP_KERNEL, cpu_to_node(i));
1476}
1477
1478#endif /* CONFIG_SMP */
1479
aab03e05
DF
1480static void switched_from_dl(struct rq *rq, struct task_struct *p)
1481{
1baca4ce 1482 if (hrtimer_active(&p->dl.dl_timer) && !dl_policy(p->policy))
aab03e05 1483 hrtimer_try_to_cancel(&p->dl.dl_timer);
1baca4ce
JL
1484
1485#ifdef CONFIG_SMP
1486 /*
1487 * Since this might be the only -deadline task on the rq,
1488 * this is the right place to try to pull some other one
1489 * from an overloaded cpu, if any.
1490 */
1491 if (!rq->dl.dl_nr_running)
1492 pull_dl_task(rq);
1493#endif
aab03e05
DF
1494}
1495
1baca4ce
JL
1496/*
1497 * When switching to -deadline, we may overload the rq, then
1498 * we try to push someone off, if possible.
1499 */
aab03e05
DF
1500static void switched_to_dl(struct rq *rq, struct task_struct *p)
1501{
1baca4ce
JL
1502 int check_resched = 1;
1503
aab03e05
DF
1504 /*
1505 * If p is throttled, don't consider the possibility
1506 * of preempting rq->curr, the check will be done right
1507 * after its runtime will get replenished.
1508 */
1509 if (unlikely(p->dl.dl_throttled))
1510 return;
1511
1512 if (p->on_rq || rq->curr != p) {
1baca4ce
JL
1513#ifdef CONFIG_SMP
1514 if (rq->dl.overloaded && push_dl_task(rq) && rq != task_rq(p))
1515 /* Only reschedule if pushing failed */
1516 check_resched = 0;
1517#endif /* CONFIG_SMP */
1518 if (check_resched && task_has_dl_policy(rq->curr))
aab03e05 1519 check_preempt_curr_dl(rq, p, 0);
aab03e05
DF
1520 }
1521}
1522
1baca4ce
JL
1523/*
1524 * If the scheduling parameters of a -deadline task changed,
1525 * a push or pull operation might be needed.
1526 */
aab03e05
DF
1527static void prio_changed_dl(struct rq *rq, struct task_struct *p,
1528 int oldprio)
1529{
1baca4ce 1530 if (p->on_rq || rq->curr == p) {
aab03e05 1531#ifdef CONFIG_SMP
1baca4ce
JL
1532 /*
1533 * This might be too much, but unfortunately
1534 * we don't have the old deadline value, and
1535 * we can't argue if the task is increasing
1536 * or lowering its prio, so...
1537 */
1538 if (!rq->dl.overloaded)
1539 pull_dl_task(rq);
1540
1541 /*
1542 * If we now have a earlier deadline task than p,
1543 * then reschedule, provided p is still on this
1544 * runqueue.
1545 */
1546 if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline) &&
1547 rq->curr == p)
1548 resched_task(p);
1549#else
1550 /*
1551 * Again, we don't know if p has a earlier
1552 * or later deadline, so let's blindly set a
1553 * (maybe not needed) rescheduling point.
1554 */
1555 resched_task(p);
1556#endif /* CONFIG_SMP */
1557 } else
1558 switched_to_dl(rq, p);
aab03e05 1559}
aab03e05
DF
1560
1561const struct sched_class dl_sched_class = {
1562 .next = &rt_sched_class,
1563 .enqueue_task = enqueue_task_dl,
1564 .dequeue_task = dequeue_task_dl,
1565 .yield_task = yield_task_dl,
1566
1567 .check_preempt_curr = check_preempt_curr_dl,
1568
1569 .pick_next_task = pick_next_task_dl,
1570 .put_prev_task = put_prev_task_dl,
1571
1572#ifdef CONFIG_SMP
1573 .select_task_rq = select_task_rq_dl,
1baca4ce
JL
1574 .set_cpus_allowed = set_cpus_allowed_dl,
1575 .rq_online = rq_online_dl,
1576 .rq_offline = rq_offline_dl,
1577 .pre_schedule = pre_schedule_dl,
1578 .post_schedule = post_schedule_dl,
1579 .task_woken = task_woken_dl,
aab03e05
DF
1580#endif
1581
1582 .set_curr_task = set_curr_task_dl,
1583 .task_tick = task_tick_dl,
1584 .task_fork = task_fork_dl,
1585 .task_dead = task_dead_dl,
1586
1587 .prio_changed = prio_changed_dl,
1588 .switched_from = switched_from_dl,
1589 .switched_to = switched_to_dl,
1590};
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