2 * Deadline Scheduling Class (SCHED_DEADLINE)
4 * Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS).
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.
12 * Copyright (C) 2012 Dario Faggioli <raistlin@linux.it>,
13 * Juri Lelli <juri.lelli@gmail.com>,
14 * Michael Trimarchi <michael@amarulasolutions.com>,
15 * Fabio Checconi <fchecconi@gmail.com>
19 #include <linux/slab.h>
21 struct dl_bandwidth def_dl_bandwidth;
23 static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
25 return container_of(dl_se, struct task_struct, dl);
28 static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq)
30 return container_of(dl_rq, struct rq, dl);
33 static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se)
35 struct task_struct *p = dl_task_of(dl_se);
36 struct rq *rq = task_rq(p);
41 static inline int on_dl_rq(struct sched_dl_entity *dl_se)
43 return !RB_EMPTY_NODE(&dl_se->rb_node);
46 static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
48 struct sched_dl_entity *dl_se = &p->dl;
50 return dl_rq->rb_leftmost == &dl_se->rb_node;
53 void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime)
55 raw_spin_lock_init(&dl_b->dl_runtime_lock);
56 dl_b->dl_period = period;
57 dl_b->dl_runtime = runtime;
60 void init_dl_bw(struct dl_bw *dl_b)
62 raw_spin_lock_init(&dl_b->lock);
63 raw_spin_lock(&def_dl_bandwidth.dl_runtime_lock);
64 if (global_rt_runtime() == RUNTIME_INF)
67 dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime());
68 raw_spin_unlock(&def_dl_bandwidth.dl_runtime_lock);
72 void init_dl_rq(struct dl_rq *dl_rq)
74 dl_rq->rb_root = RB_ROOT;
77 /* zero means no -deadline tasks */
78 dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0;
80 dl_rq->dl_nr_migratory = 0;
81 dl_rq->overloaded = 0;
82 dl_rq->pushable_dl_tasks_root = RB_ROOT;
84 init_dl_bw(&dl_rq->dl_bw);
90 static inline int dl_overloaded(struct rq *rq)
92 return atomic_read(&rq->rd->dlo_count);
95 static inline void dl_set_overload(struct rq *rq)
100 cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask);
102 * Must be visible before the overload count is
103 * set (as in sched_rt.c).
105 * Matched by the barrier in pull_dl_task().
108 atomic_inc(&rq->rd->dlo_count);
111 static inline void dl_clear_overload(struct rq *rq)
116 atomic_dec(&rq->rd->dlo_count);
117 cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask);
120 static void update_dl_migration(struct dl_rq *dl_rq)
122 if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_running > 1) {
123 if (!dl_rq->overloaded) {
124 dl_set_overload(rq_of_dl_rq(dl_rq));
125 dl_rq->overloaded = 1;
127 } else if (dl_rq->overloaded) {
128 dl_clear_overload(rq_of_dl_rq(dl_rq));
129 dl_rq->overloaded = 0;
133 static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
135 struct task_struct *p = dl_task_of(dl_se);
137 if (p->nr_cpus_allowed > 1)
138 dl_rq->dl_nr_migratory++;
140 update_dl_migration(dl_rq);
143 static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
145 struct task_struct *p = dl_task_of(dl_se);
147 if (p->nr_cpus_allowed > 1)
148 dl_rq->dl_nr_migratory--;
150 update_dl_migration(dl_rq);
154 * The list of pushable -deadline task is not a plist, like in
155 * sched_rt.c, it is an rb-tree with tasks ordered by deadline.
157 static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
159 struct dl_rq *dl_rq = &rq->dl;
160 struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_node;
161 struct rb_node *parent = NULL;
162 struct task_struct *entry;
165 BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
169 entry = rb_entry(parent, struct task_struct,
171 if (dl_entity_preempt(&p->dl, &entry->dl))
172 link = &parent->rb_left;
174 link = &parent->rb_right;
180 dl_rq->pushable_dl_tasks_leftmost = &p->pushable_dl_tasks;
182 rb_link_node(&p->pushable_dl_tasks, parent, link);
183 rb_insert_color(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
186 static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
188 struct dl_rq *dl_rq = &rq->dl;
190 if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
193 if (dl_rq->pushable_dl_tasks_leftmost == &p->pushable_dl_tasks) {
194 struct rb_node *next_node;
196 next_node = rb_next(&p->pushable_dl_tasks);
197 dl_rq->pushable_dl_tasks_leftmost = next_node;
200 rb_erase(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
201 RB_CLEAR_NODE(&p->pushable_dl_tasks);
204 static inline int has_pushable_dl_tasks(struct rq *rq)
206 return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root);
209 static int push_dl_task(struct rq *rq);
211 static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
213 return dl_task(prev);
216 static inline void set_post_schedule(struct rq *rq)
218 rq->post_schedule = has_pushable_dl_tasks(rq);
221 static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq);
223 static void dl_task_offline_migration(struct rq *rq, struct task_struct *p)
225 struct rq *later_rq = NULL;
226 bool fallback = false;
228 later_rq = find_lock_later_rq(p, rq);
234 * If we cannot preempt any rq, fall back to pick any
238 cpu = cpumask_any_and(cpu_active_mask, tsk_cpus_allowed(p));
239 if (cpu >= nr_cpu_ids) {
241 * Fail to find any suitable cpu.
242 * The task will never come back!
244 BUG_ON(dl_bandwidth_enabled());
247 * If admission control is disabled we
248 * try a little harder to let the task
251 cpu = cpumask_any(cpu_active_mask);
253 later_rq = cpu_rq(cpu);
254 double_lock_balance(rq, later_rq);
257 deactivate_task(rq, p, 0);
258 set_task_cpu(p, later_rq->cpu);
259 activate_task(later_rq, p, ENQUEUE_REPLENISH);
262 resched_curr(later_rq);
264 double_unlock_balance(rq, later_rq);
270 void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
275 void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
280 void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
285 void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
289 static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
294 static inline int pull_dl_task(struct rq *rq)
299 static inline void set_post_schedule(struct rq *rq)
302 #endif /* CONFIG_SMP */
304 static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags);
305 static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags);
306 static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
310 * We are being explicitly informed that a new instance is starting,
311 * and this means that:
312 * - the absolute deadline of the entity has to be placed at
313 * current time + relative deadline;
314 * - the runtime of the entity has to be set to the maximum value.
316 * The capability of specifying such event is useful whenever a -deadline
317 * entity wants to (try to!) synchronize its behaviour with the scheduler's
318 * one, and to (try to!) reconcile itself with its own scheduling
321 static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se,
322 struct sched_dl_entity *pi_se)
324 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
325 struct rq *rq = rq_of_dl_rq(dl_rq);
327 WARN_ON(!dl_se->dl_new || dl_se->dl_throttled);
330 * We use the regular wall clock time to set deadlines in the
331 * future; in fact, we must consider execution overheads (time
332 * spent on hardirq context, etc.).
334 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
335 dl_se->runtime = pi_se->dl_runtime;
340 * Pure Earliest Deadline First (EDF) scheduling does not deal with the
341 * possibility of a entity lasting more than what it declared, and thus
342 * exhausting its runtime.
344 * Here we are interested in making runtime overrun possible, but we do
345 * not want a entity which is misbehaving to affect the scheduling of all
347 * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
348 * is used, in order to confine each entity within its own bandwidth.
350 * This function deals exactly with that, and ensures that when the runtime
351 * of a entity is replenished, its deadline is also postponed. That ensures
352 * the overrunning entity can't interfere with other entity in the system and
353 * can't make them miss their deadlines. Reasons why this kind of overruns
354 * could happen are, typically, a entity voluntarily trying to overcome its
355 * runtime, or it just underestimated it during sched_setattr().
357 static void replenish_dl_entity(struct sched_dl_entity *dl_se,
358 struct sched_dl_entity *pi_se)
360 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
361 struct rq *rq = rq_of_dl_rq(dl_rq);
363 BUG_ON(pi_se->dl_runtime <= 0);
366 * This could be the case for a !-dl task that is boosted.
367 * Just go with full inherited parameters.
369 if (dl_se->dl_deadline == 0) {
370 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
371 dl_se->runtime = pi_se->dl_runtime;
375 * We keep moving the deadline away until we get some
376 * available runtime for the entity. This ensures correct
377 * handling of situations where the runtime overrun is
380 while (dl_se->runtime <= 0) {
381 dl_se->deadline += pi_se->dl_period;
382 dl_se->runtime += pi_se->dl_runtime;
386 * At this point, the deadline really should be "in
387 * the future" with respect to rq->clock. If it's
388 * not, we are, for some reason, lagging too much!
389 * Anyway, after having warn userspace abut that,
390 * we still try to keep the things running by
391 * resetting the deadline and the budget of the
394 if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
395 printk_deferred_once("sched: DL replenish lagged to much\n");
396 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
397 dl_se->runtime = pi_se->dl_runtime;
400 if (dl_se->dl_yielded)
401 dl_se->dl_yielded = 0;
402 if (dl_se->dl_throttled)
403 dl_se->dl_throttled = 0;
407 * Here we check if --at time t-- an entity (which is probably being
408 * [re]activated or, in general, enqueued) can use its remaining runtime
409 * and its current deadline _without_ exceeding the bandwidth it is
410 * assigned (function returns true if it can't). We are in fact applying
411 * one of the CBS rules: when a task wakes up, if the residual runtime
412 * over residual deadline fits within the allocated bandwidth, then we
413 * can keep the current (absolute) deadline and residual budget without
414 * disrupting the schedulability of the system. Otherwise, we should
415 * refill the runtime and set the deadline a period in the future,
416 * because keeping the current (absolute) deadline of the task would
417 * result in breaking guarantees promised to other tasks (refer to
418 * Documentation/scheduler/sched-deadline.txt for more informations).
420 * This function returns true if:
422 * runtime / (deadline - t) > dl_runtime / dl_period ,
424 * IOW we can't recycle current parameters.
426 * Notice that the bandwidth check is done against the period. For
427 * task with deadline equal to period this is the same of using
428 * dl_deadline instead of dl_period in the equation above.
430 static bool dl_entity_overflow(struct sched_dl_entity *dl_se,
431 struct sched_dl_entity *pi_se, u64 t)
436 * left and right are the two sides of the equation above,
437 * after a bit of shuffling to use multiplications instead
440 * Note that none of the time values involved in the two
441 * multiplications are absolute: dl_deadline and dl_runtime
442 * are the relative deadline and the maximum runtime of each
443 * instance, runtime is the runtime left for the last instance
444 * and (deadline - t), since t is rq->clock, is the time left
445 * to the (absolute) deadline. Even if overflowing the u64 type
446 * is very unlikely to occur in both cases, here we scale down
447 * as we want to avoid that risk at all. Scaling down by 10
448 * means that we reduce granularity to 1us. We are fine with it,
449 * since this is only a true/false check and, anyway, thinking
450 * of anything below microseconds resolution is actually fiction
451 * (but still we want to give the user that illusion >;).
453 left = (pi_se->dl_period >> DL_SCALE) * (dl_se->runtime >> DL_SCALE);
454 right = ((dl_se->deadline - t) >> DL_SCALE) *
455 (pi_se->dl_runtime >> DL_SCALE);
457 return dl_time_before(right, left);
461 * When a -deadline entity is queued back on the runqueue, its runtime and
462 * deadline might need updating.
464 * The policy here is that we update the deadline of the entity only if:
465 * - the current deadline is in the past,
466 * - using the remaining runtime with the current deadline would make
467 * the entity exceed its bandwidth.
469 static void update_dl_entity(struct sched_dl_entity *dl_se,
470 struct sched_dl_entity *pi_se)
472 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
473 struct rq *rq = rq_of_dl_rq(dl_rq);
476 * The arrival of a new instance needs special treatment, i.e.,
477 * the actual scheduling parameters have to be "renewed".
480 setup_new_dl_entity(dl_se, pi_se);
484 if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
485 dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) {
486 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
487 dl_se->runtime = pi_se->dl_runtime;
492 * If the entity depleted all its runtime, and if we want it to sleep
493 * while waiting for some new execution time to become available, we
494 * set the bandwidth enforcement timer to the replenishment instant
495 * and try to activate it.
497 * Notice that it is important for the caller to know if the timer
498 * actually started or not (i.e., the replenishment instant is in
499 * the future or in the past).
501 static int start_dl_timer(struct sched_dl_entity *dl_se, bool boosted)
503 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
504 struct rq *rq = rq_of_dl_rq(dl_rq);
513 * We want the timer to fire at the deadline, but considering
514 * that it is actually coming from rq->clock and not from
515 * hrtimer's time base reading.
517 act = ns_to_ktime(dl_se->deadline);
518 now = hrtimer_cb_get_time(&dl_se->dl_timer);
519 delta = ktime_to_ns(now) - rq_clock(rq);
520 act = ktime_add_ns(act, delta);
523 * If the expiry time already passed, e.g., because the value
524 * chosen as the deadline is too small, don't even try to
525 * start the timer in the past!
527 if (ktime_us_delta(act, now) < 0)
530 hrtimer_set_expires(&dl_se->dl_timer, act);
532 soft = hrtimer_get_softexpires(&dl_se->dl_timer);
533 hard = hrtimer_get_expires(&dl_se->dl_timer);
534 range = ktime_to_ns(ktime_sub(hard, soft));
535 __hrtimer_start_range_ns(&dl_se->dl_timer, soft,
536 range, HRTIMER_MODE_ABS, 0);
538 return hrtimer_active(&dl_se->dl_timer);
542 * This is the bandwidth enforcement timer callback. If here, we know
543 * a task is not on its dl_rq, since the fact that the timer was running
544 * means the task is throttled and needs a runtime replenishment.
546 * However, what we actually do depends on the fact the task is active,
547 * (it is on its rq) or has been removed from there by a call to
548 * dequeue_task_dl(). In the former case we must issue the runtime
549 * replenishment and add the task back to the dl_rq; in the latter, we just
550 * do nothing but clearing dl_throttled, so that runtime and deadline
551 * updating (and the queueing back to dl_rq) will be done by the
552 * next call to enqueue_task_dl().
554 static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
556 struct sched_dl_entity *dl_se = container_of(timer,
557 struct sched_dl_entity,
559 struct task_struct *p = dl_task_of(dl_se);
563 rq = task_rq_lock(p, &flags);
566 * We need to take care of several possible races here:
568 * - the task might have changed its scheduling policy
569 * to something different than SCHED_DEADLINE
570 * - the task might have changed its reservation parameters
571 * (through sched_setattr())
572 * - the task might have been boosted by someone else and
573 * might be in the boosting/deboosting path
575 * In all this cases we bail out, as the task is already
576 * in the runqueue or is going to be enqueued back anyway.
578 if (!dl_task(p) || dl_se->dl_new ||
579 dl_se->dl_boosted || !dl_se->dl_throttled)
587 * If we find that the rq the task was on is no longer
588 * available, we need to select a new rq.
590 if (unlikely(!rq->online)) {
591 dl_task_offline_migration(rq, p);
597 * If the throttle happened during sched-out; like:
604 * __dequeue_task_dl()
607 * We can be both throttled and !queued. Replenish the counter
608 * but do not enqueue -- wait for our wakeup to do that.
610 if (!task_on_rq_queued(p)) {
611 replenish_dl_entity(dl_se, dl_se);
615 enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
616 if (dl_task(rq->curr))
617 check_preempt_curr_dl(rq, p, 0);
622 * Queueing this task back might have overloaded rq,
623 * check if we need to kick someone away.
625 if (has_pushable_dl_tasks(rq))
629 task_rq_unlock(rq, p, &flags);
631 return HRTIMER_NORESTART;
634 void init_dl_task_timer(struct sched_dl_entity *dl_se)
636 struct hrtimer *timer = &dl_se->dl_timer;
638 hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
639 timer->function = dl_task_timer;
644 int dl_runtime_exceeded(struct rq *rq, struct sched_dl_entity *dl_se)
646 return (dl_se->runtime <= 0);
649 extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
652 * Update the current task's runtime statistics (provided it is still
653 * a -deadline task and has not been removed from the dl_rq).
655 static void update_curr_dl(struct rq *rq)
657 struct task_struct *curr = rq->curr;
658 struct sched_dl_entity *dl_se = &curr->dl;
661 if (!dl_task(curr) || !on_dl_rq(dl_se))
665 * Consumed budget is computed considering the time as
666 * observed by schedulable tasks (excluding time spent
667 * in hardirq context, etc.). Deadlines are instead
668 * computed using hard walltime. This seems to be the more
669 * natural solution, but the full ramifications of this
670 * approach need further study.
672 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
673 if (unlikely((s64)delta_exec <= 0))
676 schedstat_set(curr->se.statistics.exec_max,
677 max(curr->se.statistics.exec_max, delta_exec));
679 curr->se.sum_exec_runtime += delta_exec;
680 account_group_exec_runtime(curr, delta_exec);
682 curr->se.exec_start = rq_clock_task(rq);
683 cpuacct_charge(curr, delta_exec);
685 sched_rt_avg_update(rq, delta_exec);
687 dl_se->runtime -= dl_se->dl_yielded ? 0 : delta_exec;
688 if (dl_runtime_exceeded(rq, dl_se)) {
689 dl_se->dl_throttled = 1;
690 __dequeue_task_dl(rq, curr, 0);
691 if (unlikely(!start_dl_timer(dl_se, curr->dl.dl_boosted)))
692 enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
694 if (!is_leftmost(curr, &rq->dl))
699 * Because -- for now -- we share the rt bandwidth, we need to
700 * account our runtime there too, otherwise actual rt tasks
701 * would be able to exceed the shared quota.
703 * Account to the root rt group for now.
705 * The solution we're working towards is having the RT groups scheduled
706 * using deadline servers -- however there's a few nasties to figure
707 * out before that can happen.
709 if (rt_bandwidth_enabled()) {
710 struct rt_rq *rt_rq = &rq->rt;
712 raw_spin_lock(&rt_rq->rt_runtime_lock);
714 * We'll let actual RT tasks worry about the overflow here, we
715 * have our own CBS to keep us inline; only account when RT
716 * bandwidth is relevant.
718 if (sched_rt_bandwidth_account(rt_rq))
719 rt_rq->rt_time += delta_exec;
720 raw_spin_unlock(&rt_rq->rt_runtime_lock);
726 static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu);
728 static inline u64 next_deadline(struct rq *rq)
730 struct task_struct *next = pick_next_earliest_dl_task(rq, rq->cpu);
732 if (next && dl_prio(next->prio))
733 return next->dl.deadline;
738 static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
740 struct rq *rq = rq_of_dl_rq(dl_rq);
742 if (dl_rq->earliest_dl.curr == 0 ||
743 dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
745 * If the dl_rq had no -deadline tasks, or if the new task
746 * has shorter deadline than the current one on dl_rq, we
747 * know that the previous earliest becomes our next earliest,
748 * as the new task becomes the earliest itself.
750 dl_rq->earliest_dl.next = dl_rq->earliest_dl.curr;
751 dl_rq->earliest_dl.curr = deadline;
752 cpudl_set(&rq->rd->cpudl, rq->cpu, deadline, 1);
753 } else if (dl_rq->earliest_dl.next == 0 ||
754 dl_time_before(deadline, dl_rq->earliest_dl.next)) {
756 * On the other hand, if the new -deadline task has a
757 * a later deadline than the earliest one on dl_rq, but
758 * it is earlier than the next (if any), we must
759 * recompute the next-earliest.
761 dl_rq->earliest_dl.next = next_deadline(rq);
765 static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
767 struct rq *rq = rq_of_dl_rq(dl_rq);
770 * Since we may have removed our earliest (and/or next earliest)
771 * task we must recompute them.
773 if (!dl_rq->dl_nr_running) {
774 dl_rq->earliest_dl.curr = 0;
775 dl_rq->earliest_dl.next = 0;
776 cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
778 struct rb_node *leftmost = dl_rq->rb_leftmost;
779 struct sched_dl_entity *entry;
781 entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
782 dl_rq->earliest_dl.curr = entry->deadline;
783 dl_rq->earliest_dl.next = next_deadline(rq);
784 cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline, 1);
790 static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
791 static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
793 #endif /* CONFIG_SMP */
796 void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
798 int prio = dl_task_of(dl_se)->prio;
799 u64 deadline = dl_se->deadline;
801 WARN_ON(!dl_prio(prio));
802 dl_rq->dl_nr_running++;
803 add_nr_running(rq_of_dl_rq(dl_rq), 1);
805 inc_dl_deadline(dl_rq, deadline);
806 inc_dl_migration(dl_se, dl_rq);
810 void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
812 int prio = dl_task_of(dl_se)->prio;
814 WARN_ON(!dl_prio(prio));
815 WARN_ON(!dl_rq->dl_nr_running);
816 dl_rq->dl_nr_running--;
817 sub_nr_running(rq_of_dl_rq(dl_rq), 1);
819 dec_dl_deadline(dl_rq, dl_se->deadline);
820 dec_dl_migration(dl_se, dl_rq);
823 static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
825 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
826 struct rb_node **link = &dl_rq->rb_root.rb_node;
827 struct rb_node *parent = NULL;
828 struct sched_dl_entity *entry;
831 BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
835 entry = rb_entry(parent, struct sched_dl_entity, rb_node);
836 if (dl_time_before(dl_se->deadline, entry->deadline))
837 link = &parent->rb_left;
839 link = &parent->rb_right;
845 dl_rq->rb_leftmost = &dl_se->rb_node;
847 rb_link_node(&dl_se->rb_node, parent, link);
848 rb_insert_color(&dl_se->rb_node, &dl_rq->rb_root);
850 inc_dl_tasks(dl_se, dl_rq);
853 static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
855 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
857 if (RB_EMPTY_NODE(&dl_se->rb_node))
860 if (dl_rq->rb_leftmost == &dl_se->rb_node) {
861 struct rb_node *next_node;
863 next_node = rb_next(&dl_se->rb_node);
864 dl_rq->rb_leftmost = next_node;
867 rb_erase(&dl_se->rb_node, &dl_rq->rb_root);
868 RB_CLEAR_NODE(&dl_se->rb_node);
870 dec_dl_tasks(dl_se, dl_rq);
874 enqueue_dl_entity(struct sched_dl_entity *dl_se,
875 struct sched_dl_entity *pi_se, int flags)
877 BUG_ON(on_dl_rq(dl_se));
880 * If this is a wakeup or a new instance, the scheduling
881 * parameters of the task might need updating. Otherwise,
882 * we want a replenishment of its runtime.
884 if (dl_se->dl_new || flags & ENQUEUE_WAKEUP)
885 update_dl_entity(dl_se, pi_se);
886 else if (flags & ENQUEUE_REPLENISH)
887 replenish_dl_entity(dl_se, pi_se);
889 __enqueue_dl_entity(dl_se);
892 static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
894 __dequeue_dl_entity(dl_se);
897 static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
899 struct task_struct *pi_task = rt_mutex_get_top_task(p);
900 struct sched_dl_entity *pi_se = &p->dl;
903 * Use the scheduling parameters of the top pi-waiter
904 * task if we have one and its (relative) deadline is
905 * smaller than our one... OTW we keep our runtime and
908 if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) {
909 pi_se = &pi_task->dl;
910 } else if (!dl_prio(p->normal_prio)) {
912 * Special case in which we have a !SCHED_DEADLINE task
913 * that is going to be deboosted, but exceedes its
914 * runtime while doing so. No point in replenishing
915 * it, as it's going to return back to its original
916 * scheduling class after this.
918 BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH);
923 * If p is throttled, we do nothing. In fact, if it exhausted
924 * its budget it needs a replenishment and, since it now is on
925 * its rq, the bandwidth timer callback (which clearly has not
926 * run yet) will take care of this.
928 if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH))
931 enqueue_dl_entity(&p->dl, pi_se, flags);
933 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
934 enqueue_pushable_dl_task(rq, p);
937 static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
939 dequeue_dl_entity(&p->dl);
940 dequeue_pushable_dl_task(rq, p);
943 static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
946 __dequeue_task_dl(rq, p, flags);
950 * Yield task semantic for -deadline tasks is:
952 * get off from the CPU until our next instance, with
953 * a new runtime. This is of little use now, since we
954 * don't have a bandwidth reclaiming mechanism. Anyway,
955 * bandwidth reclaiming is planned for the future, and
956 * yield_task_dl will indicate that some spare budget
957 * is available for other task instances to use it.
959 static void yield_task_dl(struct rq *rq)
961 struct task_struct *p = rq->curr;
964 * We make the task go to sleep until its current deadline by
965 * forcing its runtime to zero. This way, update_curr_dl() stops
966 * it and the bandwidth timer will wake it up and will give it
967 * new scheduling parameters (thanks to dl_yielded=1).
969 if (p->dl.runtime > 0) {
970 rq->curr->dl.dl_yielded = 1;
976 * Tell update_rq_clock() that we've just updated,
977 * so we don't do microscopic update in schedule()
978 * and double the fastpath cost.
980 rq_clock_skip_update(rq, true);
985 static int find_later_rq(struct task_struct *task);
988 select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
990 struct task_struct *curr;
993 if (sd_flag != SD_BALANCE_WAKE)
999 curr = ACCESS_ONCE(rq->curr); /* unlocked access */
1002 * If we are dealing with a -deadline task, we must
1003 * decide where to wake it up.
1004 * If it has a later deadline and the current task
1005 * on this rq can't move (provided the waking task
1006 * can!) we prefer to send it somewhere else. On the
1007 * other hand, if it has a shorter deadline, we
1008 * try to make it stay here, it might be important.
1010 if (unlikely(dl_task(curr)) &&
1011 (curr->nr_cpus_allowed < 2 ||
1012 !dl_entity_preempt(&p->dl, &curr->dl)) &&
1013 (p->nr_cpus_allowed > 1)) {
1014 int target = find_later_rq(p);
1025 static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
1028 * Current can't be migrated, useless to reschedule,
1029 * let's hope p can move out.
1031 if (rq->curr->nr_cpus_allowed == 1 ||
1032 cpudl_find(&rq->rd->cpudl, rq->curr, NULL) == -1)
1036 * p is migratable, so let's not schedule it and
1037 * see if it is pushed or pulled somewhere else.
1039 if (p->nr_cpus_allowed != 1 &&
1040 cpudl_find(&rq->rd->cpudl, p, NULL) != -1)
1046 static int pull_dl_task(struct rq *this_rq);
1048 #endif /* CONFIG_SMP */
1051 * Only called when both the current and waking task are -deadline
1054 static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
1057 if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
1064 * In the unlikely case current and p have the same deadline
1065 * let us try to decide what's the best thing to do...
1067 if ((p->dl.deadline == rq->curr->dl.deadline) &&
1068 !test_tsk_need_resched(rq->curr))
1069 check_preempt_equal_dl(rq, p);
1070 #endif /* CONFIG_SMP */
1073 #ifdef CONFIG_SCHED_HRTICK
1074 static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1076 hrtick_start(rq, p->dl.runtime);
1078 #else /* !CONFIG_SCHED_HRTICK */
1079 static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1084 static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
1085 struct dl_rq *dl_rq)
1087 struct rb_node *left = dl_rq->rb_leftmost;
1092 return rb_entry(left, struct sched_dl_entity, rb_node);
1095 struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev)
1097 struct sched_dl_entity *dl_se;
1098 struct task_struct *p;
1099 struct dl_rq *dl_rq;
1103 if (need_pull_dl_task(rq, prev)) {
1106 * pull_rt_task() can drop (and re-acquire) rq->lock; this
1107 * means a stop task can slip in, in which case we need to
1108 * re-start task selection.
1110 if (rq->stop && task_on_rq_queued(rq->stop))
1115 * When prev is DL, we may throttle it in put_prev_task().
1116 * So, we update time before we check for dl_nr_running.
1118 if (prev->sched_class == &dl_sched_class)
1121 if (unlikely(!dl_rq->dl_nr_running))
1124 put_prev_task(rq, prev);
1126 dl_se = pick_next_dl_entity(rq, dl_rq);
1129 p = dl_task_of(dl_se);
1130 p->se.exec_start = rq_clock_task(rq);
1132 /* Running task will never be pushed. */
1133 dequeue_pushable_dl_task(rq, p);
1135 if (hrtick_enabled(rq))
1136 start_hrtick_dl(rq, p);
1138 set_post_schedule(rq);
1143 static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
1147 if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
1148 enqueue_pushable_dl_task(rq, p);
1151 static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
1156 * Even when we have runtime, update_curr_dl() might have resulted in us
1157 * not being the leftmost task anymore. In that case NEED_RESCHED will
1158 * be set and schedule() will start a new hrtick for the next task.
1160 if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 &&
1161 is_leftmost(p, &rq->dl))
1162 start_hrtick_dl(rq, p);
1165 static void task_fork_dl(struct task_struct *p)
1168 * SCHED_DEADLINE tasks cannot fork and this is achieved through
1173 static void task_dead_dl(struct task_struct *p)
1175 struct hrtimer *timer = &p->dl.dl_timer;
1176 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
1179 * Since we are TASK_DEAD we won't slip out of the domain!
1181 raw_spin_lock_irq(&dl_b->lock);
1182 /* XXX we should retain the bw until 0-lag */
1183 dl_b->total_bw -= p->dl.dl_bw;
1184 raw_spin_unlock_irq(&dl_b->lock);
1186 hrtimer_cancel(timer);
1189 static void set_curr_task_dl(struct rq *rq)
1191 struct task_struct *p = rq->curr;
1193 p->se.exec_start = rq_clock_task(rq);
1195 /* You can't push away the running task */
1196 dequeue_pushable_dl_task(rq, p);
1201 /* Only try algorithms three times */
1202 #define DL_MAX_TRIES 3
1204 static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
1206 if (!task_running(rq, p) &&
1207 cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
1212 /* Returns the second earliest -deadline task, NULL otherwise */
1213 static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu)
1215 struct rb_node *next_node = rq->dl.rb_leftmost;
1216 struct sched_dl_entity *dl_se;
1217 struct task_struct *p = NULL;
1220 next_node = rb_next(next_node);
1222 dl_se = rb_entry(next_node, struct sched_dl_entity, rb_node);
1223 p = dl_task_of(dl_se);
1225 if (pick_dl_task(rq, p, cpu))
1234 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
1236 static int find_later_rq(struct task_struct *task)
1238 struct sched_domain *sd;
1239 struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl);
1240 int this_cpu = smp_processor_id();
1241 int best_cpu, cpu = task_cpu(task);
1243 /* Make sure the mask is initialized first */
1244 if (unlikely(!later_mask))
1247 if (task->nr_cpus_allowed == 1)
1251 * We have to consider system topology and task affinity
1252 * first, then we can look for a suitable cpu.
1254 best_cpu = cpudl_find(&task_rq(task)->rd->cpudl,
1260 * If we are here, some target has been found,
1261 * the most suitable of which is cached in best_cpu.
1262 * This is, among the runqueues where the current tasks
1263 * have later deadlines than the task's one, the rq
1264 * with the latest possible one.
1266 * Now we check how well this matches with task's
1267 * affinity and system topology.
1269 * The last cpu where the task run is our first
1270 * guess, since it is most likely cache-hot there.
1272 if (cpumask_test_cpu(cpu, later_mask))
1275 * Check if this_cpu is to be skipped (i.e., it is
1276 * not in the mask) or not.
1278 if (!cpumask_test_cpu(this_cpu, later_mask))
1282 for_each_domain(cpu, sd) {
1283 if (sd->flags & SD_WAKE_AFFINE) {
1286 * If possible, preempting this_cpu is
1287 * cheaper than migrating.
1289 if (this_cpu != -1 &&
1290 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1296 * Last chance: if best_cpu is valid and is
1297 * in the mask, that becomes our choice.
1299 if (best_cpu < nr_cpu_ids &&
1300 cpumask_test_cpu(best_cpu, sched_domain_span(sd))) {
1309 * At this point, all our guesses failed, we just return
1310 * 'something', and let the caller sort the things out.
1315 cpu = cpumask_any(later_mask);
1316 if (cpu < nr_cpu_ids)
1322 /* Locks the rq it finds */
1323 static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
1325 struct rq *later_rq = NULL;
1329 for (tries = 0; tries < DL_MAX_TRIES; tries++) {
1330 cpu = find_later_rq(task);
1332 if ((cpu == -1) || (cpu == rq->cpu))
1335 later_rq = cpu_rq(cpu);
1337 /* Retry if something changed. */
1338 if (double_lock_balance(rq, later_rq)) {
1339 if (unlikely(task_rq(task) != rq ||
1340 !cpumask_test_cpu(later_rq->cpu,
1341 &task->cpus_allowed) ||
1342 task_running(rq, task) ||
1343 !task_on_rq_queued(task))) {
1344 double_unlock_balance(rq, later_rq);
1351 * If the rq we found has no -deadline task, or
1352 * its earliest one has a later deadline than our
1353 * task, the rq is a good one.
1355 if (!later_rq->dl.dl_nr_running ||
1356 dl_time_before(task->dl.deadline,
1357 later_rq->dl.earliest_dl.curr))
1360 /* Otherwise we try again. */
1361 double_unlock_balance(rq, later_rq);
1368 static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
1370 struct task_struct *p;
1372 if (!has_pushable_dl_tasks(rq))
1375 p = rb_entry(rq->dl.pushable_dl_tasks_leftmost,
1376 struct task_struct, pushable_dl_tasks);
1378 BUG_ON(rq->cpu != task_cpu(p));
1379 BUG_ON(task_current(rq, p));
1380 BUG_ON(p->nr_cpus_allowed <= 1);
1382 BUG_ON(!task_on_rq_queued(p));
1383 BUG_ON(!dl_task(p));
1389 * See if the non running -deadline tasks on this rq
1390 * can be sent to some other CPU where they can preempt
1391 * and start executing.
1393 static int push_dl_task(struct rq *rq)
1395 struct task_struct *next_task;
1396 struct rq *later_rq;
1399 if (!rq->dl.overloaded)
1402 next_task = pick_next_pushable_dl_task(rq);
1407 if (unlikely(next_task == rq->curr)) {
1413 * If next_task preempts rq->curr, and rq->curr
1414 * can move away, it makes sense to just reschedule
1415 * without going further in pushing next_task.
1417 if (dl_task(rq->curr) &&
1418 dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
1419 rq->curr->nr_cpus_allowed > 1) {
1424 /* We might release rq lock */
1425 get_task_struct(next_task);
1427 /* Will lock the rq it'll find */
1428 later_rq = find_lock_later_rq(next_task, rq);
1430 struct task_struct *task;
1433 * We must check all this again, since
1434 * find_lock_later_rq releases rq->lock and it is
1435 * then possible that next_task has migrated.
1437 task = pick_next_pushable_dl_task(rq);
1438 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1440 * The task is still there. We don't try
1441 * again, some other cpu will pull it when ready.
1450 put_task_struct(next_task);
1455 deactivate_task(rq, next_task, 0);
1456 set_task_cpu(next_task, later_rq->cpu);
1457 activate_task(later_rq, next_task, 0);
1460 resched_curr(later_rq);
1462 double_unlock_balance(rq, later_rq);
1465 put_task_struct(next_task);
1470 static void push_dl_tasks(struct rq *rq)
1472 /* Terminates as it moves a -deadline task */
1473 while (push_dl_task(rq))
1477 static int pull_dl_task(struct rq *this_rq)
1479 int this_cpu = this_rq->cpu, ret = 0, cpu;
1480 struct task_struct *p;
1482 u64 dmin = LONG_MAX;
1484 if (likely(!dl_overloaded(this_rq)))
1488 * Match the barrier from dl_set_overloaded; this guarantees that if we
1489 * see overloaded we must also see the dlo_mask bit.
1493 for_each_cpu(cpu, this_rq->rd->dlo_mask) {
1494 if (this_cpu == cpu)
1497 src_rq = cpu_rq(cpu);
1500 * It looks racy, abd it is! However, as in sched_rt.c,
1501 * we are fine with this.
1503 if (this_rq->dl.dl_nr_running &&
1504 dl_time_before(this_rq->dl.earliest_dl.curr,
1505 src_rq->dl.earliest_dl.next))
1508 /* Might drop this_rq->lock */
1509 double_lock_balance(this_rq, src_rq);
1512 * If there are no more pullable tasks on the
1513 * rq, we're done with it.
1515 if (src_rq->dl.dl_nr_running <= 1)
1518 p = pick_next_earliest_dl_task(src_rq, this_cpu);
1521 * We found a task to be pulled if:
1522 * - it preempts our current (if there's one),
1523 * - it will preempt the last one we pulled (if any).
1525 if (p && dl_time_before(p->dl.deadline, dmin) &&
1526 (!this_rq->dl.dl_nr_running ||
1527 dl_time_before(p->dl.deadline,
1528 this_rq->dl.earliest_dl.curr))) {
1529 WARN_ON(p == src_rq->curr);
1530 WARN_ON(!task_on_rq_queued(p));
1533 * Then we pull iff p has actually an earlier
1534 * deadline than the current task of its runqueue.
1536 if (dl_time_before(p->dl.deadline,
1537 src_rq->curr->dl.deadline))
1542 deactivate_task(src_rq, p, 0);
1543 set_task_cpu(p, this_cpu);
1544 activate_task(this_rq, p, 0);
1545 dmin = p->dl.deadline;
1547 /* Is there any other task even earlier? */
1550 double_unlock_balance(this_rq, src_rq);
1556 static void post_schedule_dl(struct rq *rq)
1562 * Since the task is not running and a reschedule is not going to happen
1563 * anytime soon on its runqueue, we try pushing it away now.
1565 static void task_woken_dl(struct rq *rq, struct task_struct *p)
1567 if (!task_running(rq, p) &&
1568 !test_tsk_need_resched(rq->curr) &&
1569 has_pushable_dl_tasks(rq) &&
1570 p->nr_cpus_allowed > 1 &&
1571 dl_task(rq->curr) &&
1572 (rq->curr->nr_cpus_allowed < 2 ||
1573 !dl_entity_preempt(&p->dl, &rq->curr->dl))) {
1578 static void set_cpus_allowed_dl(struct task_struct *p,
1579 const struct cpumask *new_mask)
1582 struct root_domain *src_rd;
1585 BUG_ON(!dl_task(p));
1590 * Migrating a SCHED_DEADLINE task between exclusive
1591 * cpusets (different root_domains) entails a bandwidth
1592 * update. We already made space for us in the destination
1593 * domain (see cpuset_can_attach()).
1595 if (!cpumask_intersects(src_rd->span, new_mask)) {
1596 struct dl_bw *src_dl_b;
1598 src_dl_b = dl_bw_of(cpu_of(rq));
1600 * We now free resources of the root_domain we are migrating
1601 * off. In the worst case, sched_setattr() may temporary fail
1602 * until we complete the update.
1604 raw_spin_lock(&src_dl_b->lock);
1605 __dl_clear(src_dl_b, p->dl.dl_bw);
1606 raw_spin_unlock(&src_dl_b->lock);
1610 * Update only if the task is actually running (i.e.,
1611 * it is on the rq AND it is not throttled).
1613 if (!on_dl_rq(&p->dl))
1616 weight = cpumask_weight(new_mask);
1619 * Only update if the process changes its state from whether it
1620 * can migrate or not.
1622 if ((p->nr_cpus_allowed > 1) == (weight > 1))
1626 * The process used to be able to migrate OR it can now migrate
1629 if (!task_current(rq, p))
1630 dequeue_pushable_dl_task(rq, p);
1631 BUG_ON(!rq->dl.dl_nr_migratory);
1632 rq->dl.dl_nr_migratory--;
1634 if (!task_current(rq, p))
1635 enqueue_pushable_dl_task(rq, p);
1636 rq->dl.dl_nr_migratory++;
1639 update_dl_migration(&rq->dl);
1642 /* Assumes rq->lock is held */
1643 static void rq_online_dl(struct rq *rq)
1645 if (rq->dl.overloaded)
1646 dl_set_overload(rq);
1648 cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
1649 if (rq->dl.dl_nr_running > 0)
1650 cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr, 1);
1653 /* Assumes rq->lock is held */
1654 static void rq_offline_dl(struct rq *rq)
1656 if (rq->dl.overloaded)
1657 dl_clear_overload(rq);
1659 cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
1660 cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
1663 void init_sched_dl_class(void)
1667 for_each_possible_cpu(i)
1668 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
1669 GFP_KERNEL, cpu_to_node(i));
1672 #endif /* CONFIG_SMP */
1675 * Ensure p's dl_timer is cancelled. May drop rq->lock for a while.
1677 static void cancel_dl_timer(struct rq *rq, struct task_struct *p)
1679 struct hrtimer *dl_timer = &p->dl.dl_timer;
1681 /* Nobody will change task's class if pi_lock is held */
1682 lockdep_assert_held(&p->pi_lock);
1684 if (hrtimer_active(dl_timer)) {
1685 int ret = hrtimer_try_to_cancel(dl_timer);
1687 if (unlikely(ret == -1)) {
1689 * Note, p may migrate OR new deadline tasks
1690 * may appear in rq when we are unlocking it.
1691 * A caller of us must be fine with that.
1693 raw_spin_unlock(&rq->lock);
1694 hrtimer_cancel(dl_timer);
1695 raw_spin_lock(&rq->lock);
1700 static void switched_from_dl(struct rq *rq, struct task_struct *p)
1702 /* XXX we should retain the bw until 0-lag */
1703 cancel_dl_timer(rq, p);
1704 __dl_clear_params(p);
1707 * Since this might be the only -deadline task on the rq,
1708 * this is the right place to try to pull some other one
1709 * from an overloaded cpu, if any.
1711 if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
1714 if (pull_dl_task(rq))
1719 * When switching to -deadline, we may overload the rq, then
1720 * we try to push someone off, if possible.
1722 static void switched_to_dl(struct rq *rq, struct task_struct *p)
1724 int check_resched = 1;
1726 if (task_on_rq_queued(p) && rq->curr != p) {
1728 if (p->nr_cpus_allowed > 1 && rq->dl.overloaded &&
1729 push_dl_task(rq) && rq != task_rq(p))
1730 /* Only reschedule if pushing failed */
1732 #endif /* CONFIG_SMP */
1733 if (check_resched) {
1734 if (dl_task(rq->curr))
1735 check_preempt_curr_dl(rq, p, 0);
1743 * If the scheduling parameters of a -deadline task changed,
1744 * a push or pull operation might be needed.
1746 static void prio_changed_dl(struct rq *rq, struct task_struct *p,
1749 if (task_on_rq_queued(p) || rq->curr == p) {
1752 * This might be too much, but unfortunately
1753 * we don't have the old deadline value, and
1754 * we can't argue if the task is increasing
1755 * or lowering its prio, so...
1757 if (!rq->dl.overloaded)
1761 * If we now have a earlier deadline task than p,
1762 * then reschedule, provided p is still on this
1765 if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline) &&
1770 * Again, we don't know if p has a earlier
1771 * or later deadline, so let's blindly set a
1772 * (maybe not needed) rescheduling point.
1775 #endif /* CONFIG_SMP */
1777 switched_to_dl(rq, p);
1780 const struct sched_class dl_sched_class = {
1781 .next = &rt_sched_class,
1782 .enqueue_task = enqueue_task_dl,
1783 .dequeue_task = dequeue_task_dl,
1784 .yield_task = yield_task_dl,
1786 .check_preempt_curr = check_preempt_curr_dl,
1788 .pick_next_task = pick_next_task_dl,
1789 .put_prev_task = put_prev_task_dl,
1792 .select_task_rq = select_task_rq_dl,
1793 .set_cpus_allowed = set_cpus_allowed_dl,
1794 .rq_online = rq_online_dl,
1795 .rq_offline = rq_offline_dl,
1796 .post_schedule = post_schedule_dl,
1797 .task_woken = task_woken_dl,
1800 .set_curr_task = set_curr_task_dl,
1801 .task_tick = task_tick_dl,
1802 .task_fork = task_fork_dl,
1803 .task_dead = task_dead_dl,
1805 .prio_changed = prio_changed_dl,
1806 .switched_from = switched_from_dl,
1807 .switched_to = switched_to_dl,
1809 .update_curr = update_curr_dl,
1812 #ifdef CONFIG_SCHED_DEBUG
1813 extern void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq);
1815 void print_dl_stats(struct seq_file *m, int cpu)
1817 print_dl_rq(m, cpu, &cpu_rq(cpu)->dl);
1819 #endif /* CONFIG_SCHED_DEBUG */