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;
181 dl_rq->earliest_dl.next = p->dl.deadline;
184 rb_link_node(&p->pushable_dl_tasks, parent, link);
185 rb_insert_color(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
188 static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
190 struct dl_rq *dl_rq = &rq->dl;
192 if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
195 if (dl_rq->pushable_dl_tasks_leftmost == &p->pushable_dl_tasks) {
196 struct rb_node *next_node;
198 next_node = rb_next(&p->pushable_dl_tasks);
199 dl_rq->pushable_dl_tasks_leftmost = next_node;
201 dl_rq->earliest_dl.next = rb_entry(next_node,
202 struct task_struct, pushable_dl_tasks)->dl.deadline;
206 rb_erase(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
207 RB_CLEAR_NODE(&p->pushable_dl_tasks);
210 static inline int has_pushable_dl_tasks(struct rq *rq)
212 return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root);
215 static int push_dl_task(struct rq *rq);
217 static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
219 return dl_task(prev);
222 static DEFINE_PER_CPU(struct callback_head, dl_push_head);
223 static DEFINE_PER_CPU(struct callback_head, dl_pull_head);
225 static void push_dl_tasks(struct rq *);
226 static void pull_dl_task(struct rq *);
228 static inline void queue_push_tasks(struct rq *rq)
230 if (!has_pushable_dl_tasks(rq))
233 queue_balance_callback(rq, &per_cpu(dl_push_head, rq->cpu), push_dl_tasks);
236 static inline void queue_pull_task(struct rq *rq)
238 queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task);
241 static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq);
243 static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p)
245 struct rq *later_rq = NULL;
246 bool fallback = false;
248 later_rq = find_lock_later_rq(p, rq);
254 * If we cannot preempt any rq, fall back to pick any
258 cpu = cpumask_any_and(cpu_active_mask, tsk_cpus_allowed(p));
259 if (cpu >= nr_cpu_ids) {
261 * Fail to find any suitable cpu.
262 * The task will never come back!
264 BUG_ON(dl_bandwidth_enabled());
267 * If admission control is disabled we
268 * try a little harder to let the task
271 cpu = cpumask_any(cpu_active_mask);
273 later_rq = cpu_rq(cpu);
274 double_lock_balance(rq, later_rq);
278 * By now the task is replenished and enqueued; migrate it.
280 deactivate_task(rq, p, 0);
281 set_task_cpu(p, later_rq->cpu);
282 activate_task(later_rq, p, 0);
285 resched_curr(later_rq);
287 double_unlock_balance(later_rq, rq);
295 void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
300 void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
305 void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
310 void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
314 static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
319 static inline void pull_dl_task(struct rq *rq)
323 static inline void queue_push_tasks(struct rq *rq)
327 static inline void queue_pull_task(struct rq *rq)
330 #endif /* CONFIG_SMP */
332 static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags);
333 static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags);
334 static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
338 * We are being explicitly informed that a new instance is starting,
339 * and this means that:
340 * - the absolute deadline of the entity has to be placed at
341 * current time + relative deadline;
342 * - the runtime of the entity has to be set to the maximum value.
344 * The capability of specifying such event is useful whenever a -deadline
345 * entity wants to (try to!) synchronize its behaviour with the scheduler's
346 * one, and to (try to!) reconcile itself with its own scheduling
349 static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se,
350 struct sched_dl_entity *pi_se)
352 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
353 struct rq *rq = rq_of_dl_rq(dl_rq);
355 WARN_ON(!dl_se->dl_new || dl_se->dl_throttled);
358 * We use the regular wall clock time to set deadlines in the
359 * future; in fact, we must consider execution overheads (time
360 * spent on hardirq context, etc.).
362 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
363 dl_se->runtime = pi_se->dl_runtime;
368 * Pure Earliest Deadline First (EDF) scheduling does not deal with the
369 * possibility of a entity lasting more than what it declared, and thus
370 * exhausting its runtime.
372 * Here we are interested in making runtime overrun possible, but we do
373 * not want a entity which is misbehaving to affect the scheduling of all
375 * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
376 * is used, in order to confine each entity within its own bandwidth.
378 * This function deals exactly with that, and ensures that when the runtime
379 * of a entity is replenished, its deadline is also postponed. That ensures
380 * the overrunning entity can't interfere with other entity in the system and
381 * can't make them miss their deadlines. Reasons why this kind of overruns
382 * could happen are, typically, a entity voluntarily trying to overcome its
383 * runtime, or it just underestimated it during sched_setattr().
385 static void replenish_dl_entity(struct sched_dl_entity *dl_se,
386 struct sched_dl_entity *pi_se)
388 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
389 struct rq *rq = rq_of_dl_rq(dl_rq);
391 BUG_ON(pi_se->dl_runtime <= 0);
394 * This could be the case for a !-dl task that is boosted.
395 * Just go with full inherited parameters.
397 if (dl_se->dl_deadline == 0) {
398 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
399 dl_se->runtime = pi_se->dl_runtime;
402 if (dl_se->dl_yielded && dl_se->runtime > 0)
406 * We keep moving the deadline away until we get some
407 * available runtime for the entity. This ensures correct
408 * handling of situations where the runtime overrun is
411 while (dl_se->runtime <= 0) {
412 dl_se->deadline += pi_se->dl_period;
413 dl_se->runtime += pi_se->dl_runtime;
417 * At this point, the deadline really should be "in
418 * the future" with respect to rq->clock. If it's
419 * not, we are, for some reason, lagging too much!
420 * Anyway, after having warn userspace abut that,
421 * we still try to keep the things running by
422 * resetting the deadline and the budget of the
425 if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
426 printk_deferred_once("sched: DL replenish lagged too much\n");
427 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
428 dl_se->runtime = pi_se->dl_runtime;
431 if (dl_se->dl_yielded)
432 dl_se->dl_yielded = 0;
433 if (dl_se->dl_throttled)
434 dl_se->dl_throttled = 0;
438 * Here we check if --at time t-- an entity (which is probably being
439 * [re]activated or, in general, enqueued) can use its remaining runtime
440 * and its current deadline _without_ exceeding the bandwidth it is
441 * assigned (function returns true if it can't). We are in fact applying
442 * one of the CBS rules: when a task wakes up, if the residual runtime
443 * over residual deadline fits within the allocated bandwidth, then we
444 * can keep the current (absolute) deadline and residual budget without
445 * disrupting the schedulability of the system. Otherwise, we should
446 * refill the runtime and set the deadline a period in the future,
447 * because keeping the current (absolute) deadline of the task would
448 * result in breaking guarantees promised to other tasks (refer to
449 * Documentation/scheduler/sched-deadline.txt for more informations).
451 * This function returns true if:
453 * runtime / (deadline - t) > dl_runtime / dl_period ,
455 * IOW we can't recycle current parameters.
457 * Notice that the bandwidth check is done against the period. For
458 * task with deadline equal to period this is the same of using
459 * dl_deadline instead of dl_period in the equation above.
461 static bool dl_entity_overflow(struct sched_dl_entity *dl_se,
462 struct sched_dl_entity *pi_se, u64 t)
467 * left and right are the two sides of the equation above,
468 * after a bit of shuffling to use multiplications instead
471 * Note that none of the time values involved in the two
472 * multiplications are absolute: dl_deadline and dl_runtime
473 * are the relative deadline and the maximum runtime of each
474 * instance, runtime is the runtime left for the last instance
475 * and (deadline - t), since t is rq->clock, is the time left
476 * to the (absolute) deadline. Even if overflowing the u64 type
477 * is very unlikely to occur in both cases, here we scale down
478 * as we want to avoid that risk at all. Scaling down by 10
479 * means that we reduce granularity to 1us. We are fine with it,
480 * since this is only a true/false check and, anyway, thinking
481 * of anything below microseconds resolution is actually fiction
482 * (but still we want to give the user that illusion >;).
484 left = (pi_se->dl_period >> DL_SCALE) * (dl_se->runtime >> DL_SCALE);
485 right = ((dl_se->deadline - t) >> DL_SCALE) *
486 (pi_se->dl_runtime >> DL_SCALE);
488 return dl_time_before(right, left);
492 * When a -deadline entity is queued back on the runqueue, its runtime and
493 * deadline might need updating.
495 * The policy here is that we update the deadline of the entity only if:
496 * - the current deadline is in the past,
497 * - using the remaining runtime with the current deadline would make
498 * the entity exceed its bandwidth.
500 static void update_dl_entity(struct sched_dl_entity *dl_se,
501 struct sched_dl_entity *pi_se)
503 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
504 struct rq *rq = rq_of_dl_rq(dl_rq);
507 * The arrival of a new instance needs special treatment, i.e.,
508 * the actual scheduling parameters have to be "renewed".
511 setup_new_dl_entity(dl_se, pi_se);
515 if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
516 dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) {
517 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
518 dl_se->runtime = pi_se->dl_runtime;
523 * If the entity depleted all its runtime, and if we want it to sleep
524 * while waiting for some new execution time to become available, we
525 * set the bandwidth enforcement timer to the replenishment instant
526 * and try to activate it.
528 * Notice that it is important for the caller to know if the timer
529 * actually started or not (i.e., the replenishment instant is in
530 * the future or in the past).
532 static int start_dl_timer(struct task_struct *p)
534 struct sched_dl_entity *dl_se = &p->dl;
535 struct hrtimer *timer = &dl_se->dl_timer;
536 struct rq *rq = task_rq(p);
540 lockdep_assert_held(&rq->lock);
543 * We want the timer to fire at the deadline, but considering
544 * that it is actually coming from rq->clock and not from
545 * hrtimer's time base reading.
547 act = ns_to_ktime(dl_se->deadline);
548 now = hrtimer_cb_get_time(timer);
549 delta = ktime_to_ns(now) - rq_clock(rq);
550 act = ktime_add_ns(act, delta);
553 * If the expiry time already passed, e.g., because the value
554 * chosen as the deadline is too small, don't even try to
555 * start the timer in the past!
557 if (ktime_us_delta(act, now) < 0)
561 * !enqueued will guarantee another callback; even if one is already in
562 * progress. This ensures a balanced {get,put}_task_struct().
564 * The race against __run_timer() clearing the enqueued state is
565 * harmless because we're holding task_rq()->lock, therefore the timer
566 * expiring after we've done the check will wait on its task_rq_lock()
567 * and observe our state.
569 if (!hrtimer_is_queued(timer)) {
571 hrtimer_start(timer, act, HRTIMER_MODE_ABS);
578 * This is the bandwidth enforcement timer callback. If here, we know
579 * a task is not on its dl_rq, since the fact that the timer was running
580 * means the task is throttled and needs a runtime replenishment.
582 * However, what we actually do depends on the fact the task is active,
583 * (it is on its rq) or has been removed from there by a call to
584 * dequeue_task_dl(). In the former case we must issue the runtime
585 * replenishment and add the task back to the dl_rq; in the latter, we just
586 * do nothing but clearing dl_throttled, so that runtime and deadline
587 * updating (and the queueing back to dl_rq) will be done by the
588 * next call to enqueue_task_dl().
590 static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
592 struct sched_dl_entity *dl_se = container_of(timer,
593 struct sched_dl_entity,
595 struct task_struct *p = dl_task_of(dl_se);
599 rq = task_rq_lock(p, &flags);
602 * The task might have changed its scheduling policy to something
603 * different than SCHED_DEADLINE (through switched_fromd_dl()).
606 __dl_clear_params(p);
611 * This is possible if switched_from_dl() raced against a running
612 * callback that took the above !dl_task() path and we've since then
613 * switched back into SCHED_DEADLINE.
615 * There's nothing to do except drop our task reference.
621 * The task might have been boosted by someone else and might be in the
622 * boosting/deboosting path, its not throttled.
624 if (dl_se->dl_boosted)
628 * Spurious timer due to start_dl_timer() race; or we already received
629 * a replenishment from rt_mutex_setprio().
631 if (!dl_se->dl_throttled)
638 * If the throttle happened during sched-out; like:
645 * __dequeue_task_dl()
648 * We can be both throttled and !queued. Replenish the counter
649 * but do not enqueue -- wait for our wakeup to do that.
651 if (!task_on_rq_queued(p)) {
652 replenish_dl_entity(dl_se, dl_se);
656 enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
657 if (dl_task(rq->curr))
658 check_preempt_curr_dl(rq, p, 0);
664 * Perform balancing operations here; after the replenishments. We
665 * cannot drop rq->lock before this, otherwise the assertion in
666 * start_dl_timer() about not missing updates is not true.
668 * If we find that the rq the task was on is no longer available, we
669 * need to select a new rq.
671 * XXX figure out if select_task_rq_dl() deals with offline cpus.
673 if (unlikely(!rq->online))
674 rq = dl_task_offline_migration(rq, p);
677 * Queueing this task back might have overloaded rq, check if we need
678 * to kick someone away.
680 if (has_pushable_dl_tasks(rq)) {
682 * Nothing relies on rq->lock after this, so its safe to drop
685 lockdep_unpin_lock(&rq->lock);
687 lockdep_pin_lock(&rq->lock);
692 task_rq_unlock(rq, p, &flags);
695 * This can free the task_struct, including this hrtimer, do not touch
696 * anything related to that after this.
700 return HRTIMER_NORESTART;
703 void init_dl_task_timer(struct sched_dl_entity *dl_se)
705 struct hrtimer *timer = &dl_se->dl_timer;
707 hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
708 timer->function = dl_task_timer;
712 int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
714 return (dl_se->runtime <= 0);
717 extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
720 * Update the current task's runtime statistics (provided it is still
721 * a -deadline task and has not been removed from the dl_rq).
723 static void update_curr_dl(struct rq *rq)
725 struct task_struct *curr = rq->curr;
726 struct sched_dl_entity *dl_se = &curr->dl;
729 if (!dl_task(curr) || !on_dl_rq(dl_se))
733 * Consumed budget is computed considering the time as
734 * observed by schedulable tasks (excluding time spent
735 * in hardirq context, etc.). Deadlines are instead
736 * computed using hard walltime. This seems to be the more
737 * natural solution, but the full ramifications of this
738 * approach need further study.
740 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
741 if (unlikely((s64)delta_exec <= 0)) {
742 if (unlikely(dl_se->dl_yielded))
747 schedstat_set(curr->se.statistics.exec_max,
748 max(curr->se.statistics.exec_max, delta_exec));
750 curr->se.sum_exec_runtime += delta_exec;
751 account_group_exec_runtime(curr, delta_exec);
753 curr->se.exec_start = rq_clock_task(rq);
754 cpuacct_charge(curr, delta_exec);
756 sched_rt_avg_update(rq, delta_exec);
758 dl_se->runtime -= delta_exec;
761 if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
762 dl_se->dl_throttled = 1;
763 __dequeue_task_dl(rq, curr, 0);
764 if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr)))
765 enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
767 if (!is_leftmost(curr, &rq->dl))
772 * Because -- for now -- we share the rt bandwidth, we need to
773 * account our runtime there too, otherwise actual rt tasks
774 * would be able to exceed the shared quota.
776 * Account to the root rt group for now.
778 * The solution we're working towards is having the RT groups scheduled
779 * using deadline servers -- however there's a few nasties to figure
780 * out before that can happen.
782 if (rt_bandwidth_enabled()) {
783 struct rt_rq *rt_rq = &rq->rt;
785 raw_spin_lock(&rt_rq->rt_runtime_lock);
787 * We'll let actual RT tasks worry about the overflow here, we
788 * have our own CBS to keep us inline; only account when RT
789 * bandwidth is relevant.
791 if (sched_rt_bandwidth_account(rt_rq))
792 rt_rq->rt_time += delta_exec;
793 raw_spin_unlock(&rt_rq->rt_runtime_lock);
799 static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
801 struct rq *rq = rq_of_dl_rq(dl_rq);
803 if (dl_rq->earliest_dl.curr == 0 ||
804 dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
805 dl_rq->earliest_dl.curr = deadline;
806 cpudl_set(&rq->rd->cpudl, rq->cpu, deadline, 1);
810 static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
812 struct rq *rq = rq_of_dl_rq(dl_rq);
815 * Since we may have removed our earliest (and/or next earliest)
816 * task we must recompute them.
818 if (!dl_rq->dl_nr_running) {
819 dl_rq->earliest_dl.curr = 0;
820 dl_rq->earliest_dl.next = 0;
821 cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
823 struct rb_node *leftmost = dl_rq->rb_leftmost;
824 struct sched_dl_entity *entry;
826 entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
827 dl_rq->earliest_dl.curr = entry->deadline;
828 cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline, 1);
834 static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
835 static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
837 #endif /* CONFIG_SMP */
840 void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
842 int prio = dl_task_of(dl_se)->prio;
843 u64 deadline = dl_se->deadline;
845 WARN_ON(!dl_prio(prio));
846 dl_rq->dl_nr_running++;
847 add_nr_running(rq_of_dl_rq(dl_rq), 1);
849 inc_dl_deadline(dl_rq, deadline);
850 inc_dl_migration(dl_se, dl_rq);
854 void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
856 int prio = dl_task_of(dl_se)->prio;
858 WARN_ON(!dl_prio(prio));
859 WARN_ON(!dl_rq->dl_nr_running);
860 dl_rq->dl_nr_running--;
861 sub_nr_running(rq_of_dl_rq(dl_rq), 1);
863 dec_dl_deadline(dl_rq, dl_se->deadline);
864 dec_dl_migration(dl_se, dl_rq);
867 static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
869 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
870 struct rb_node **link = &dl_rq->rb_root.rb_node;
871 struct rb_node *parent = NULL;
872 struct sched_dl_entity *entry;
875 BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
879 entry = rb_entry(parent, struct sched_dl_entity, rb_node);
880 if (dl_time_before(dl_se->deadline, entry->deadline))
881 link = &parent->rb_left;
883 link = &parent->rb_right;
889 dl_rq->rb_leftmost = &dl_se->rb_node;
891 rb_link_node(&dl_se->rb_node, parent, link);
892 rb_insert_color(&dl_se->rb_node, &dl_rq->rb_root);
894 inc_dl_tasks(dl_se, dl_rq);
897 static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
899 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
901 if (RB_EMPTY_NODE(&dl_se->rb_node))
904 if (dl_rq->rb_leftmost == &dl_se->rb_node) {
905 struct rb_node *next_node;
907 next_node = rb_next(&dl_se->rb_node);
908 dl_rq->rb_leftmost = next_node;
911 rb_erase(&dl_se->rb_node, &dl_rq->rb_root);
912 RB_CLEAR_NODE(&dl_se->rb_node);
914 dec_dl_tasks(dl_se, dl_rq);
918 enqueue_dl_entity(struct sched_dl_entity *dl_se,
919 struct sched_dl_entity *pi_se, int flags)
921 BUG_ON(on_dl_rq(dl_se));
924 * If this is a wakeup or a new instance, the scheduling
925 * parameters of the task might need updating. Otherwise,
926 * we want a replenishment of its runtime.
928 if (dl_se->dl_new || flags & ENQUEUE_WAKEUP)
929 update_dl_entity(dl_se, pi_se);
930 else if (flags & ENQUEUE_REPLENISH)
931 replenish_dl_entity(dl_se, pi_se);
933 __enqueue_dl_entity(dl_se);
936 static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
938 __dequeue_dl_entity(dl_se);
941 static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
943 struct task_struct *pi_task = rt_mutex_get_top_task(p);
944 struct sched_dl_entity *pi_se = &p->dl;
947 * Use the scheduling parameters of the top pi-waiter
948 * task if we have one and its (absolute) deadline is
949 * smaller than our one... OTW we keep our runtime and
952 if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) {
953 pi_se = &pi_task->dl;
954 } else if (!dl_prio(p->normal_prio)) {
956 * Special case in which we have a !SCHED_DEADLINE task
957 * that is going to be deboosted, but exceedes its
958 * runtime while doing so. No point in replenishing
959 * it, as it's going to return back to its original
960 * scheduling class after this.
962 BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH);
967 * If p is throttled, we do nothing. In fact, if it exhausted
968 * its budget it needs a replenishment and, since it now is on
969 * its rq, the bandwidth timer callback (which clearly has not
970 * run yet) will take care of this.
972 if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH))
975 enqueue_dl_entity(&p->dl, pi_se, flags);
977 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
978 enqueue_pushable_dl_task(rq, p);
981 static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
983 dequeue_dl_entity(&p->dl);
984 dequeue_pushable_dl_task(rq, p);
987 static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
990 __dequeue_task_dl(rq, p, flags);
994 * Yield task semantic for -deadline tasks is:
996 * get off from the CPU until our next instance, with
997 * a new runtime. This is of little use now, since we
998 * don't have a bandwidth reclaiming mechanism. Anyway,
999 * bandwidth reclaiming is planned for the future, and
1000 * yield_task_dl will indicate that some spare budget
1001 * is available for other task instances to use it.
1003 static void yield_task_dl(struct rq *rq)
1006 * We make the task go to sleep until its current deadline by
1007 * forcing its runtime to zero. This way, update_curr_dl() stops
1008 * it and the bandwidth timer will wake it up and will give it
1009 * new scheduling parameters (thanks to dl_yielded=1).
1011 rq->curr->dl.dl_yielded = 1;
1013 update_rq_clock(rq);
1016 * Tell update_rq_clock() that we've just updated,
1017 * so we don't do microscopic update in schedule()
1018 * and double the fastpath cost.
1020 rq_clock_skip_update(rq, true);
1025 static int find_later_rq(struct task_struct *task);
1028 select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
1030 struct task_struct *curr;
1033 if (sd_flag != SD_BALANCE_WAKE)
1039 curr = READ_ONCE(rq->curr); /* unlocked access */
1042 * If we are dealing with a -deadline task, we must
1043 * decide where to wake it up.
1044 * If it has a later deadline and the current task
1045 * on this rq can't move (provided the waking task
1046 * can!) we prefer to send it somewhere else. On the
1047 * other hand, if it has a shorter deadline, we
1048 * try to make it stay here, it might be important.
1050 if (unlikely(dl_task(curr)) &&
1051 (curr->nr_cpus_allowed < 2 ||
1052 !dl_entity_preempt(&p->dl, &curr->dl)) &&
1053 (p->nr_cpus_allowed > 1)) {
1054 int target = find_later_rq(p);
1057 (dl_time_before(p->dl.deadline,
1058 cpu_rq(target)->dl.earliest_dl.curr) ||
1059 (cpu_rq(target)->dl.dl_nr_running == 0)))
1068 static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
1071 * Current can't be migrated, useless to reschedule,
1072 * let's hope p can move out.
1074 if (rq->curr->nr_cpus_allowed == 1 ||
1075 cpudl_find(&rq->rd->cpudl, rq->curr, NULL) == -1)
1079 * p is migratable, so let's not schedule it and
1080 * see if it is pushed or pulled somewhere else.
1082 if (p->nr_cpus_allowed != 1 &&
1083 cpudl_find(&rq->rd->cpudl, p, NULL) != -1)
1089 #endif /* CONFIG_SMP */
1092 * Only called when both the current and waking task are -deadline
1095 static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
1098 if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
1105 * In the unlikely case current and p have the same deadline
1106 * let us try to decide what's the best thing to do...
1108 if ((p->dl.deadline == rq->curr->dl.deadline) &&
1109 !test_tsk_need_resched(rq->curr))
1110 check_preempt_equal_dl(rq, p);
1111 #endif /* CONFIG_SMP */
1114 #ifdef CONFIG_SCHED_HRTICK
1115 static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1117 hrtick_start(rq, p->dl.runtime);
1119 #else /* !CONFIG_SCHED_HRTICK */
1120 static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1125 static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
1126 struct dl_rq *dl_rq)
1128 struct rb_node *left = dl_rq->rb_leftmost;
1133 return rb_entry(left, struct sched_dl_entity, rb_node);
1136 struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev)
1138 struct sched_dl_entity *dl_se;
1139 struct task_struct *p;
1140 struct dl_rq *dl_rq;
1144 if (need_pull_dl_task(rq, prev)) {
1146 * This is OK, because current is on_cpu, which avoids it being
1147 * picked for load-balance and preemption/IRQs are still
1148 * disabled avoiding further scheduler activity on it and we're
1149 * being very careful to re-start the picking loop.
1151 lockdep_unpin_lock(&rq->lock);
1153 lockdep_pin_lock(&rq->lock);
1155 * pull_rt_task() can drop (and re-acquire) rq->lock; this
1156 * means a stop task can slip in, in which case we need to
1157 * re-start task selection.
1159 if (rq->stop && task_on_rq_queued(rq->stop))
1164 * When prev is DL, we may throttle it in put_prev_task().
1165 * So, we update time before we check for dl_nr_running.
1167 if (prev->sched_class == &dl_sched_class)
1170 if (unlikely(!dl_rq->dl_nr_running))
1173 put_prev_task(rq, prev);
1175 dl_se = pick_next_dl_entity(rq, dl_rq);
1178 p = dl_task_of(dl_se);
1179 p->se.exec_start = rq_clock_task(rq);
1181 /* Running task will never be pushed. */
1182 dequeue_pushable_dl_task(rq, p);
1184 if (hrtick_enabled(rq))
1185 start_hrtick_dl(rq, p);
1187 queue_push_tasks(rq);
1192 static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
1196 if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
1197 enqueue_pushable_dl_task(rq, p);
1200 static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
1205 * Even when we have runtime, update_curr_dl() might have resulted in us
1206 * not being the leftmost task anymore. In that case NEED_RESCHED will
1207 * be set and schedule() will start a new hrtick for the next task.
1209 if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 &&
1210 is_leftmost(p, &rq->dl))
1211 start_hrtick_dl(rq, p);
1214 static void task_fork_dl(struct task_struct *p)
1217 * SCHED_DEADLINE tasks cannot fork and this is achieved through
1222 static void task_dead_dl(struct task_struct *p)
1224 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
1227 * Since we are TASK_DEAD we won't slip out of the domain!
1229 raw_spin_lock_irq(&dl_b->lock);
1230 /* XXX we should retain the bw until 0-lag */
1231 dl_b->total_bw -= p->dl.dl_bw;
1232 raw_spin_unlock_irq(&dl_b->lock);
1235 static void set_curr_task_dl(struct rq *rq)
1237 struct task_struct *p = rq->curr;
1239 p->se.exec_start = rq_clock_task(rq);
1241 /* You can't push away the running task */
1242 dequeue_pushable_dl_task(rq, p);
1247 /* Only try algorithms three times */
1248 #define DL_MAX_TRIES 3
1250 static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
1252 if (!task_running(rq, p) &&
1253 cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
1259 * Return the earliest pushable rq's task, which is suitable to be executed
1260 * on the CPU, NULL otherwise:
1262 static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu)
1264 struct rb_node *next_node = rq->dl.pushable_dl_tasks_leftmost;
1265 struct task_struct *p = NULL;
1267 if (!has_pushable_dl_tasks(rq))
1272 p = rb_entry(next_node, struct task_struct, pushable_dl_tasks);
1274 if (pick_dl_task(rq, p, cpu))
1277 next_node = rb_next(next_node);
1284 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
1286 static int find_later_rq(struct task_struct *task)
1288 struct sched_domain *sd;
1289 struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl);
1290 int this_cpu = smp_processor_id();
1291 int best_cpu, cpu = task_cpu(task);
1293 /* Make sure the mask is initialized first */
1294 if (unlikely(!later_mask))
1297 if (task->nr_cpus_allowed == 1)
1301 * We have to consider system topology and task affinity
1302 * first, then we can look for a suitable cpu.
1304 best_cpu = cpudl_find(&task_rq(task)->rd->cpudl,
1310 * If we are here, some target has been found,
1311 * the most suitable of which is cached in best_cpu.
1312 * This is, among the runqueues where the current tasks
1313 * have later deadlines than the task's one, the rq
1314 * with the latest possible one.
1316 * Now we check how well this matches with task's
1317 * affinity and system topology.
1319 * The last cpu where the task run is our first
1320 * guess, since it is most likely cache-hot there.
1322 if (cpumask_test_cpu(cpu, later_mask))
1325 * Check if this_cpu is to be skipped (i.e., it is
1326 * not in the mask) or not.
1328 if (!cpumask_test_cpu(this_cpu, later_mask))
1332 for_each_domain(cpu, sd) {
1333 if (sd->flags & SD_WAKE_AFFINE) {
1336 * If possible, preempting this_cpu is
1337 * cheaper than migrating.
1339 if (this_cpu != -1 &&
1340 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1346 * Last chance: if best_cpu is valid and is
1347 * in the mask, that becomes our choice.
1349 if (best_cpu < nr_cpu_ids &&
1350 cpumask_test_cpu(best_cpu, sched_domain_span(sd))) {
1359 * At this point, all our guesses failed, we just return
1360 * 'something', and let the caller sort the things out.
1365 cpu = cpumask_any(later_mask);
1366 if (cpu < nr_cpu_ids)
1372 /* Locks the rq it finds */
1373 static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
1375 struct rq *later_rq = NULL;
1379 for (tries = 0; tries < DL_MAX_TRIES; tries++) {
1380 cpu = find_later_rq(task);
1382 if ((cpu == -1) || (cpu == rq->cpu))
1385 later_rq = cpu_rq(cpu);
1387 if (later_rq->dl.dl_nr_running &&
1388 !dl_time_before(task->dl.deadline,
1389 later_rq->dl.earliest_dl.curr)) {
1391 * Target rq has tasks of equal or earlier deadline,
1392 * retrying does not release any lock and is unlikely
1393 * to yield a different result.
1399 /* Retry if something changed. */
1400 if (double_lock_balance(rq, later_rq)) {
1401 if (unlikely(task_rq(task) != rq ||
1402 !cpumask_test_cpu(later_rq->cpu,
1403 &task->cpus_allowed) ||
1404 task_running(rq, task) ||
1405 !task_on_rq_queued(task))) {
1406 double_unlock_balance(rq, later_rq);
1413 * If the rq we found has no -deadline task, or
1414 * its earliest one has a later deadline than our
1415 * task, the rq is a good one.
1417 if (!later_rq->dl.dl_nr_running ||
1418 dl_time_before(task->dl.deadline,
1419 later_rq->dl.earliest_dl.curr))
1422 /* Otherwise we try again. */
1423 double_unlock_balance(rq, later_rq);
1430 static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
1432 struct task_struct *p;
1434 if (!has_pushable_dl_tasks(rq))
1437 p = rb_entry(rq->dl.pushable_dl_tasks_leftmost,
1438 struct task_struct, pushable_dl_tasks);
1440 BUG_ON(rq->cpu != task_cpu(p));
1441 BUG_ON(task_current(rq, p));
1442 BUG_ON(p->nr_cpus_allowed <= 1);
1444 BUG_ON(!task_on_rq_queued(p));
1445 BUG_ON(!dl_task(p));
1451 * See if the non running -deadline tasks on this rq
1452 * can be sent to some other CPU where they can preempt
1453 * and start executing.
1455 static int push_dl_task(struct rq *rq)
1457 struct task_struct *next_task;
1458 struct rq *later_rq;
1461 if (!rq->dl.overloaded)
1464 next_task = pick_next_pushable_dl_task(rq);
1469 if (unlikely(next_task == rq->curr)) {
1475 * If next_task preempts rq->curr, and rq->curr
1476 * can move away, it makes sense to just reschedule
1477 * without going further in pushing next_task.
1479 if (dl_task(rq->curr) &&
1480 dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
1481 rq->curr->nr_cpus_allowed > 1) {
1486 /* We might release rq lock */
1487 get_task_struct(next_task);
1489 /* Will lock the rq it'll find */
1490 later_rq = find_lock_later_rq(next_task, rq);
1492 struct task_struct *task;
1495 * We must check all this again, since
1496 * find_lock_later_rq releases rq->lock and it is
1497 * then possible that next_task has migrated.
1499 task = pick_next_pushable_dl_task(rq);
1500 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1502 * The task is still there. We don't try
1503 * again, some other cpu will pull it when ready.
1512 put_task_struct(next_task);
1517 deactivate_task(rq, next_task, 0);
1518 set_task_cpu(next_task, later_rq->cpu);
1519 activate_task(later_rq, next_task, 0);
1522 resched_curr(later_rq);
1524 double_unlock_balance(rq, later_rq);
1527 put_task_struct(next_task);
1532 static void push_dl_tasks(struct rq *rq)
1534 /* push_dl_task() will return true if it moved a -deadline task */
1535 while (push_dl_task(rq))
1539 static void pull_dl_task(struct rq *this_rq)
1541 int this_cpu = this_rq->cpu, cpu;
1542 struct task_struct *p;
1543 bool resched = false;
1545 u64 dmin = LONG_MAX;
1547 if (likely(!dl_overloaded(this_rq)))
1551 * Match the barrier from dl_set_overloaded; this guarantees that if we
1552 * see overloaded we must also see the dlo_mask bit.
1556 for_each_cpu(cpu, this_rq->rd->dlo_mask) {
1557 if (this_cpu == cpu)
1560 src_rq = cpu_rq(cpu);
1563 * It looks racy, abd it is! However, as in sched_rt.c,
1564 * we are fine with this.
1566 if (this_rq->dl.dl_nr_running &&
1567 dl_time_before(this_rq->dl.earliest_dl.curr,
1568 src_rq->dl.earliest_dl.next))
1571 /* Might drop this_rq->lock */
1572 double_lock_balance(this_rq, src_rq);
1575 * If there are no more pullable tasks on the
1576 * rq, we're done with it.
1578 if (src_rq->dl.dl_nr_running <= 1)
1581 p = pick_earliest_pushable_dl_task(src_rq, this_cpu);
1584 * We found a task to be pulled if:
1585 * - it preempts our current (if there's one),
1586 * - it will preempt the last one we pulled (if any).
1588 if (p && dl_time_before(p->dl.deadline, dmin) &&
1589 (!this_rq->dl.dl_nr_running ||
1590 dl_time_before(p->dl.deadline,
1591 this_rq->dl.earliest_dl.curr))) {
1592 WARN_ON(p == src_rq->curr);
1593 WARN_ON(!task_on_rq_queued(p));
1596 * Then we pull iff p has actually an earlier
1597 * deadline than the current task of its runqueue.
1599 if (dl_time_before(p->dl.deadline,
1600 src_rq->curr->dl.deadline))
1605 deactivate_task(src_rq, p, 0);
1606 set_task_cpu(p, this_cpu);
1607 activate_task(this_rq, p, 0);
1608 dmin = p->dl.deadline;
1610 /* Is there any other task even earlier? */
1613 double_unlock_balance(this_rq, src_rq);
1617 resched_curr(this_rq);
1621 * Since the task is not running and a reschedule is not going to happen
1622 * anytime soon on its runqueue, we try pushing it away now.
1624 static void task_woken_dl(struct rq *rq, struct task_struct *p)
1626 if (!task_running(rq, p) &&
1627 !test_tsk_need_resched(rq->curr) &&
1628 p->nr_cpus_allowed > 1 &&
1629 dl_task(rq->curr) &&
1630 (rq->curr->nr_cpus_allowed < 2 ||
1631 !dl_entity_preempt(&p->dl, &rq->curr->dl))) {
1636 static void set_cpus_allowed_dl(struct task_struct *p,
1637 const struct cpumask *new_mask)
1639 struct root_domain *src_rd;
1642 BUG_ON(!dl_task(p));
1647 * Migrating a SCHED_DEADLINE task between exclusive
1648 * cpusets (different root_domains) entails a bandwidth
1649 * update. We already made space for us in the destination
1650 * domain (see cpuset_can_attach()).
1652 if (!cpumask_intersects(src_rd->span, new_mask)) {
1653 struct dl_bw *src_dl_b;
1655 src_dl_b = dl_bw_of(cpu_of(rq));
1657 * We now free resources of the root_domain we are migrating
1658 * off. In the worst case, sched_setattr() may temporary fail
1659 * until we complete the update.
1661 raw_spin_lock(&src_dl_b->lock);
1662 __dl_clear(src_dl_b, p->dl.dl_bw);
1663 raw_spin_unlock(&src_dl_b->lock);
1666 set_cpus_allowed_common(p, new_mask);
1669 /* Assumes rq->lock is held */
1670 static void rq_online_dl(struct rq *rq)
1672 if (rq->dl.overloaded)
1673 dl_set_overload(rq);
1675 cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
1676 if (rq->dl.dl_nr_running > 0)
1677 cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr, 1);
1680 /* Assumes rq->lock is held */
1681 static void rq_offline_dl(struct rq *rq)
1683 if (rq->dl.overloaded)
1684 dl_clear_overload(rq);
1686 cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
1687 cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
1690 void __init init_sched_dl_class(void)
1694 for_each_possible_cpu(i)
1695 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
1696 GFP_KERNEL, cpu_to_node(i));
1699 #endif /* CONFIG_SMP */
1701 static void switched_from_dl(struct rq *rq, struct task_struct *p)
1704 * Start the deadline timer; if we switch back to dl before this we'll
1705 * continue consuming our current CBS slice. If we stay outside of
1706 * SCHED_DEADLINE until the deadline passes, the timer will reset the
1709 if (!start_dl_timer(p))
1710 __dl_clear_params(p);
1713 * Since this might be the only -deadline task on the rq,
1714 * this is the right place to try to pull some other one
1715 * from an overloaded cpu, if any.
1717 if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
1720 queue_pull_task(rq);
1724 * When switching to -deadline, we may overload the rq, then
1725 * we try to push someone off, if possible.
1727 static void switched_to_dl(struct rq *rq, struct task_struct *p)
1729 if (task_on_rq_queued(p) && rq->curr != p) {
1731 if (p->nr_cpus_allowed > 1 && rq->dl.overloaded)
1732 queue_push_tasks(rq);
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)
1758 queue_pull_task(rq);
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))
1769 * Again, we don't know if p has a earlier
1770 * or later deadline, so let's blindly set a
1771 * (maybe not needed) rescheduling point.
1774 #endif /* CONFIG_SMP */
1778 const struct sched_class dl_sched_class = {
1779 .next = &rt_sched_class,
1780 .enqueue_task = enqueue_task_dl,
1781 .dequeue_task = dequeue_task_dl,
1782 .yield_task = yield_task_dl,
1784 .check_preempt_curr = check_preempt_curr_dl,
1786 .pick_next_task = pick_next_task_dl,
1787 .put_prev_task = put_prev_task_dl,
1790 .select_task_rq = select_task_rq_dl,
1791 .set_cpus_allowed = set_cpus_allowed_dl,
1792 .rq_online = rq_online_dl,
1793 .rq_offline = rq_offline_dl,
1794 .task_woken = task_woken_dl,
1797 .set_curr_task = set_curr_task_dl,
1798 .task_tick = task_tick_dl,
1799 .task_fork = task_fork_dl,
1800 .task_dead = task_dead_dl,
1802 .prio_changed = prio_changed_dl,
1803 .switched_from = switched_from_dl,
1804 .switched_to = switched_to_dl,
1806 .update_curr = update_curr_dl,
1809 #ifdef CONFIG_SCHED_DEBUG
1810 extern void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq);
1812 void print_dl_stats(struct seq_file *m, int cpu)
1814 print_dl_rq(m, cpu, &cpu_rq(cpu)->dl);
1816 #endif /* CONFIG_SCHED_DEBUG */