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_time_before(rq_clock(rq), dl_se->deadline));
358 * We are racing with the deadline timer. So, do nothing because
359 * the deadline timer handler will take care of properly recharging
360 * the runtime and postponing the deadline
362 if (dl_se->dl_throttled)
366 * We use the regular wall clock time to set deadlines in the
367 * future; in fact, we must consider execution overheads (time
368 * spent on hardirq context, etc.).
370 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
371 dl_se->runtime = pi_se->dl_runtime;
375 * Pure Earliest Deadline First (EDF) scheduling does not deal with the
376 * possibility of a entity lasting more than what it declared, and thus
377 * exhausting its runtime.
379 * Here we are interested in making runtime overrun possible, but we do
380 * not want a entity which is misbehaving to affect the scheduling of all
382 * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
383 * is used, in order to confine each entity within its own bandwidth.
385 * This function deals exactly with that, and ensures that when the runtime
386 * of a entity is replenished, its deadline is also postponed. That ensures
387 * the overrunning entity can't interfere with other entity in the system and
388 * can't make them miss their deadlines. Reasons why this kind of overruns
389 * could happen are, typically, a entity voluntarily trying to overcome its
390 * runtime, or it just underestimated it during sched_setattr().
392 static void replenish_dl_entity(struct sched_dl_entity *dl_se,
393 struct sched_dl_entity *pi_se)
395 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
396 struct rq *rq = rq_of_dl_rq(dl_rq);
398 BUG_ON(pi_se->dl_runtime <= 0);
401 * This could be the case for a !-dl task that is boosted.
402 * Just go with full inherited parameters.
404 if (dl_se->dl_deadline == 0) {
405 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
406 dl_se->runtime = pi_se->dl_runtime;
409 if (dl_se->dl_yielded && dl_se->runtime > 0)
413 * We keep moving the deadline away until we get some
414 * available runtime for the entity. This ensures correct
415 * handling of situations where the runtime overrun is
418 while (dl_se->runtime <= 0) {
419 dl_se->deadline += pi_se->dl_period;
420 dl_se->runtime += pi_se->dl_runtime;
424 * At this point, the deadline really should be "in
425 * the future" with respect to rq->clock. If it's
426 * not, we are, for some reason, lagging too much!
427 * Anyway, after having warn userspace abut that,
428 * we still try to keep the things running by
429 * resetting the deadline and the budget of the
432 if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
433 printk_deferred_once("sched: DL replenish lagged too much\n");
434 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
435 dl_se->runtime = pi_se->dl_runtime;
438 if (dl_se->dl_yielded)
439 dl_se->dl_yielded = 0;
440 if (dl_se->dl_throttled)
441 dl_se->dl_throttled = 0;
445 * Here we check if --at time t-- an entity (which is probably being
446 * [re]activated or, in general, enqueued) can use its remaining runtime
447 * and its current deadline _without_ exceeding the bandwidth it is
448 * assigned (function returns true if it can't). We are in fact applying
449 * one of the CBS rules: when a task wakes up, if the residual runtime
450 * over residual deadline fits within the allocated bandwidth, then we
451 * can keep the current (absolute) deadline and residual budget without
452 * disrupting the schedulability of the system. Otherwise, we should
453 * refill the runtime and set the deadline a period in the future,
454 * because keeping the current (absolute) deadline of the task would
455 * result in breaking guarantees promised to other tasks (refer to
456 * Documentation/scheduler/sched-deadline.txt for more informations).
458 * This function returns true if:
460 * runtime / (deadline - t) > dl_runtime / dl_period ,
462 * IOW we can't recycle current parameters.
464 * Notice that the bandwidth check is done against the period. For
465 * task with deadline equal to period this is the same of using
466 * dl_deadline instead of dl_period in the equation above.
468 static bool dl_entity_overflow(struct sched_dl_entity *dl_se,
469 struct sched_dl_entity *pi_se, u64 t)
474 * left and right are the two sides of the equation above,
475 * after a bit of shuffling to use multiplications instead
478 * Note that none of the time values involved in the two
479 * multiplications are absolute: dl_deadline and dl_runtime
480 * are the relative deadline and the maximum runtime of each
481 * instance, runtime is the runtime left for the last instance
482 * and (deadline - t), since t is rq->clock, is the time left
483 * to the (absolute) deadline. Even if overflowing the u64 type
484 * is very unlikely to occur in both cases, here we scale down
485 * as we want to avoid that risk at all. Scaling down by 10
486 * means that we reduce granularity to 1us. We are fine with it,
487 * since this is only a true/false check and, anyway, thinking
488 * of anything below microseconds resolution is actually fiction
489 * (but still we want to give the user that illusion >;).
491 left = (pi_se->dl_period >> DL_SCALE) * (dl_se->runtime >> DL_SCALE);
492 right = ((dl_se->deadline - t) >> DL_SCALE) *
493 (pi_se->dl_runtime >> DL_SCALE);
495 return dl_time_before(right, left);
499 * When a -deadline entity is queued back on the runqueue, its runtime and
500 * deadline might need updating.
502 * The policy here is that we update the deadline of the entity only if:
503 * - the current deadline is in the past,
504 * - using the remaining runtime with the current deadline would make
505 * the entity exceed its bandwidth.
507 static void update_dl_entity(struct sched_dl_entity *dl_se,
508 struct sched_dl_entity *pi_se)
510 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
511 struct rq *rq = rq_of_dl_rq(dl_rq);
513 if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
514 dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) {
515 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
516 dl_se->runtime = pi_se->dl_runtime;
521 * If the entity depleted all its runtime, and if we want it to sleep
522 * while waiting for some new execution time to become available, we
523 * set the bandwidth enforcement timer to the replenishment instant
524 * and try to activate it.
526 * Notice that it is important for the caller to know if the timer
527 * actually started or not (i.e., the replenishment instant is in
528 * the future or in the past).
530 static int start_dl_timer(struct task_struct *p)
532 struct sched_dl_entity *dl_se = &p->dl;
533 struct hrtimer *timer = &dl_se->dl_timer;
534 struct rq *rq = task_rq(p);
538 lockdep_assert_held(&rq->lock);
541 * We want the timer to fire at the deadline, but considering
542 * that it is actually coming from rq->clock and not from
543 * hrtimer's time base reading.
545 act = ns_to_ktime(dl_se->deadline);
546 now = hrtimer_cb_get_time(timer);
547 delta = ktime_to_ns(now) - rq_clock(rq);
548 act = ktime_add_ns(act, delta);
551 * If the expiry time already passed, e.g., because the value
552 * chosen as the deadline is too small, don't even try to
553 * start the timer in the past!
555 if (ktime_us_delta(act, now) < 0)
559 * !enqueued will guarantee another callback; even if one is already in
560 * progress. This ensures a balanced {get,put}_task_struct().
562 * The race against __run_timer() clearing the enqueued state is
563 * harmless because we're holding task_rq()->lock, therefore the timer
564 * expiring after we've done the check will wait on its task_rq_lock()
565 * and observe our state.
567 if (!hrtimer_is_queued(timer)) {
569 hrtimer_start(timer, act, HRTIMER_MODE_ABS);
576 * This is the bandwidth enforcement timer callback. If here, we know
577 * a task is not on its dl_rq, since the fact that the timer was running
578 * means the task is throttled and needs a runtime replenishment.
580 * However, what we actually do depends on the fact the task is active,
581 * (it is on its rq) or has been removed from there by a call to
582 * dequeue_task_dl(). In the former case we must issue the runtime
583 * replenishment and add the task back to the dl_rq; in the latter, we just
584 * do nothing but clearing dl_throttled, so that runtime and deadline
585 * updating (and the queueing back to dl_rq) will be done by the
586 * next call to enqueue_task_dl().
588 static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
590 struct sched_dl_entity *dl_se = container_of(timer,
591 struct sched_dl_entity,
593 struct task_struct *p = dl_task_of(dl_se);
597 rq = task_rq_lock(p, &flags);
600 * The task might have changed its scheduling policy to something
601 * different than SCHED_DEADLINE (through switched_fromd_dl()).
604 __dl_clear_params(p);
609 * The task might have been boosted by someone else and might be in the
610 * boosting/deboosting path, its not throttled.
612 if (dl_se->dl_boosted)
616 * Spurious timer due to start_dl_timer() race; or we already received
617 * a replenishment from rt_mutex_setprio().
619 if (!dl_se->dl_throttled)
626 * If the throttle happened during sched-out; like:
633 * __dequeue_task_dl()
636 * We can be both throttled and !queued. Replenish the counter
637 * but do not enqueue -- wait for our wakeup to do that.
639 if (!task_on_rq_queued(p)) {
640 replenish_dl_entity(dl_se, dl_se);
644 enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
645 if (dl_task(rq->curr))
646 check_preempt_curr_dl(rq, p, 0);
652 * Perform balancing operations here; after the replenishments. We
653 * cannot drop rq->lock before this, otherwise the assertion in
654 * start_dl_timer() about not missing updates is not true.
656 * If we find that the rq the task was on is no longer available, we
657 * need to select a new rq.
659 * XXX figure out if select_task_rq_dl() deals with offline cpus.
661 if (unlikely(!rq->online))
662 rq = dl_task_offline_migration(rq, p);
665 * Queueing this task back might have overloaded rq, check if we need
666 * to kick someone away.
668 if (has_pushable_dl_tasks(rq)) {
670 * Nothing relies on rq->lock after this, so its safe to drop
673 lockdep_unpin_lock(&rq->lock);
675 lockdep_pin_lock(&rq->lock);
680 task_rq_unlock(rq, p, &flags);
683 * This can free the task_struct, including this hrtimer, do not touch
684 * anything related to that after this.
688 return HRTIMER_NORESTART;
691 void init_dl_task_timer(struct sched_dl_entity *dl_se)
693 struct hrtimer *timer = &dl_se->dl_timer;
695 hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
696 timer->function = dl_task_timer;
700 int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
702 return (dl_se->runtime <= 0);
705 extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
708 * Update the current task's runtime statistics (provided it is still
709 * a -deadline task and has not been removed from the dl_rq).
711 static void update_curr_dl(struct rq *rq)
713 struct task_struct *curr = rq->curr;
714 struct sched_dl_entity *dl_se = &curr->dl;
717 if (!dl_task(curr) || !on_dl_rq(dl_se))
721 * Consumed budget is computed considering the time as
722 * observed by schedulable tasks (excluding time spent
723 * in hardirq context, etc.). Deadlines are instead
724 * computed using hard walltime. This seems to be the more
725 * natural solution, but the full ramifications of this
726 * approach need further study.
728 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
729 if (unlikely((s64)delta_exec <= 0)) {
730 if (unlikely(dl_se->dl_yielded))
735 schedstat_set(curr->se.statistics.exec_max,
736 max(curr->se.statistics.exec_max, delta_exec));
738 curr->se.sum_exec_runtime += delta_exec;
739 account_group_exec_runtime(curr, delta_exec);
741 curr->se.exec_start = rq_clock_task(rq);
742 cpuacct_charge(curr, delta_exec);
744 sched_rt_avg_update(rq, delta_exec);
746 dl_se->runtime -= delta_exec;
749 if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
750 dl_se->dl_throttled = 1;
751 __dequeue_task_dl(rq, curr, 0);
752 if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr)))
753 enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
755 if (!is_leftmost(curr, &rq->dl))
760 * Because -- for now -- we share the rt bandwidth, we need to
761 * account our runtime there too, otherwise actual rt tasks
762 * would be able to exceed the shared quota.
764 * Account to the root rt group for now.
766 * The solution we're working towards is having the RT groups scheduled
767 * using deadline servers -- however there's a few nasties to figure
768 * out before that can happen.
770 if (rt_bandwidth_enabled()) {
771 struct rt_rq *rt_rq = &rq->rt;
773 raw_spin_lock(&rt_rq->rt_runtime_lock);
775 * We'll let actual RT tasks worry about the overflow here, we
776 * have our own CBS to keep us inline; only account when RT
777 * bandwidth is relevant.
779 if (sched_rt_bandwidth_account(rt_rq))
780 rt_rq->rt_time += delta_exec;
781 raw_spin_unlock(&rt_rq->rt_runtime_lock);
787 static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
789 struct rq *rq = rq_of_dl_rq(dl_rq);
791 if (dl_rq->earliest_dl.curr == 0 ||
792 dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
793 dl_rq->earliest_dl.curr = deadline;
794 cpudl_set(&rq->rd->cpudl, rq->cpu, deadline, 1);
798 static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
800 struct rq *rq = rq_of_dl_rq(dl_rq);
803 * Since we may have removed our earliest (and/or next earliest)
804 * task we must recompute them.
806 if (!dl_rq->dl_nr_running) {
807 dl_rq->earliest_dl.curr = 0;
808 dl_rq->earliest_dl.next = 0;
809 cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
811 struct rb_node *leftmost = dl_rq->rb_leftmost;
812 struct sched_dl_entity *entry;
814 entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
815 dl_rq->earliest_dl.curr = entry->deadline;
816 cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline, 1);
822 static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
823 static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
825 #endif /* CONFIG_SMP */
828 void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
830 int prio = dl_task_of(dl_se)->prio;
831 u64 deadline = dl_se->deadline;
833 WARN_ON(!dl_prio(prio));
834 dl_rq->dl_nr_running++;
835 add_nr_running(rq_of_dl_rq(dl_rq), 1);
837 inc_dl_deadline(dl_rq, deadline);
838 inc_dl_migration(dl_se, dl_rq);
842 void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
844 int prio = dl_task_of(dl_se)->prio;
846 WARN_ON(!dl_prio(prio));
847 WARN_ON(!dl_rq->dl_nr_running);
848 dl_rq->dl_nr_running--;
849 sub_nr_running(rq_of_dl_rq(dl_rq), 1);
851 dec_dl_deadline(dl_rq, dl_se->deadline);
852 dec_dl_migration(dl_se, dl_rq);
855 static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
857 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
858 struct rb_node **link = &dl_rq->rb_root.rb_node;
859 struct rb_node *parent = NULL;
860 struct sched_dl_entity *entry;
863 BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
867 entry = rb_entry(parent, struct sched_dl_entity, rb_node);
868 if (dl_time_before(dl_se->deadline, entry->deadline))
869 link = &parent->rb_left;
871 link = &parent->rb_right;
877 dl_rq->rb_leftmost = &dl_se->rb_node;
879 rb_link_node(&dl_se->rb_node, parent, link);
880 rb_insert_color(&dl_se->rb_node, &dl_rq->rb_root);
882 inc_dl_tasks(dl_se, dl_rq);
885 static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
887 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
889 if (RB_EMPTY_NODE(&dl_se->rb_node))
892 if (dl_rq->rb_leftmost == &dl_se->rb_node) {
893 struct rb_node *next_node;
895 next_node = rb_next(&dl_se->rb_node);
896 dl_rq->rb_leftmost = next_node;
899 rb_erase(&dl_se->rb_node, &dl_rq->rb_root);
900 RB_CLEAR_NODE(&dl_se->rb_node);
902 dec_dl_tasks(dl_se, dl_rq);
906 enqueue_dl_entity(struct sched_dl_entity *dl_se,
907 struct sched_dl_entity *pi_se, int flags)
909 BUG_ON(on_dl_rq(dl_se));
912 * If this is a wakeup or a new instance, the scheduling
913 * parameters of the task might need updating. Otherwise,
914 * we want a replenishment of its runtime.
916 if (flags & ENQUEUE_WAKEUP)
917 update_dl_entity(dl_se, pi_se);
918 else if (flags & ENQUEUE_REPLENISH)
919 replenish_dl_entity(dl_se, pi_se);
921 __enqueue_dl_entity(dl_se);
924 static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
926 __dequeue_dl_entity(dl_se);
929 static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
931 struct task_struct *pi_task = rt_mutex_get_top_task(p);
932 struct sched_dl_entity *pi_se = &p->dl;
935 * Use the scheduling parameters of the top pi-waiter
936 * task if we have one and its (absolute) deadline is
937 * smaller than our one... OTW we keep our runtime and
940 if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) {
941 pi_se = &pi_task->dl;
942 } else if (!dl_prio(p->normal_prio)) {
944 * Special case in which we have a !SCHED_DEADLINE task
945 * that is going to be deboosted, but exceedes its
946 * runtime while doing so. No point in replenishing
947 * it, as it's going to return back to its original
948 * scheduling class after this.
950 BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH);
955 * If p is throttled, we do nothing. In fact, if it exhausted
956 * its budget it needs a replenishment and, since it now is on
957 * its rq, the bandwidth timer callback (which clearly has not
958 * run yet) will take care of this.
960 if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH))
963 enqueue_dl_entity(&p->dl, pi_se, flags);
965 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
966 enqueue_pushable_dl_task(rq, p);
969 static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
971 dequeue_dl_entity(&p->dl);
972 dequeue_pushable_dl_task(rq, p);
975 static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
978 __dequeue_task_dl(rq, p, flags);
982 * Yield task semantic for -deadline tasks is:
984 * get off from the CPU until our next instance, with
985 * a new runtime. This is of little use now, since we
986 * don't have a bandwidth reclaiming mechanism. Anyway,
987 * bandwidth reclaiming is planned for the future, and
988 * yield_task_dl will indicate that some spare budget
989 * is available for other task instances to use it.
991 static void yield_task_dl(struct rq *rq)
994 * We make the task go to sleep until its current deadline by
995 * forcing its runtime to zero. This way, update_curr_dl() stops
996 * it and the bandwidth timer will wake it up and will give it
997 * new scheduling parameters (thanks to dl_yielded=1).
999 rq->curr->dl.dl_yielded = 1;
1001 update_rq_clock(rq);
1004 * Tell update_rq_clock() that we've just updated,
1005 * so we don't do microscopic update in schedule()
1006 * and double the fastpath cost.
1008 rq_clock_skip_update(rq, true);
1013 static int find_later_rq(struct task_struct *task);
1016 select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
1018 struct task_struct *curr;
1021 if (sd_flag != SD_BALANCE_WAKE)
1027 curr = READ_ONCE(rq->curr); /* unlocked access */
1030 * If we are dealing with a -deadline task, we must
1031 * decide where to wake it up.
1032 * If it has a later deadline and the current task
1033 * on this rq can't move (provided the waking task
1034 * can!) we prefer to send it somewhere else. On the
1035 * other hand, if it has a shorter deadline, we
1036 * try to make it stay here, it might be important.
1038 if (unlikely(dl_task(curr)) &&
1039 (curr->nr_cpus_allowed < 2 ||
1040 !dl_entity_preempt(&p->dl, &curr->dl)) &&
1041 (p->nr_cpus_allowed > 1)) {
1042 int target = find_later_rq(p);
1045 (dl_time_before(p->dl.deadline,
1046 cpu_rq(target)->dl.earliest_dl.curr) ||
1047 (cpu_rq(target)->dl.dl_nr_running == 0)))
1056 static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
1059 * Current can't be migrated, useless to reschedule,
1060 * let's hope p can move out.
1062 if (rq->curr->nr_cpus_allowed == 1 ||
1063 cpudl_find(&rq->rd->cpudl, rq->curr, NULL) == -1)
1067 * p is migratable, so let's not schedule it and
1068 * see if it is pushed or pulled somewhere else.
1070 if (p->nr_cpus_allowed != 1 &&
1071 cpudl_find(&rq->rd->cpudl, p, NULL) != -1)
1077 #endif /* CONFIG_SMP */
1080 * Only called when both the current and waking task are -deadline
1083 static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
1086 if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
1093 * In the unlikely case current and p have the same deadline
1094 * let us try to decide what's the best thing to do...
1096 if ((p->dl.deadline == rq->curr->dl.deadline) &&
1097 !test_tsk_need_resched(rq->curr))
1098 check_preempt_equal_dl(rq, p);
1099 #endif /* CONFIG_SMP */
1102 #ifdef CONFIG_SCHED_HRTICK
1103 static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1105 hrtick_start(rq, p->dl.runtime);
1107 #else /* !CONFIG_SCHED_HRTICK */
1108 static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1113 static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
1114 struct dl_rq *dl_rq)
1116 struct rb_node *left = dl_rq->rb_leftmost;
1121 return rb_entry(left, struct sched_dl_entity, rb_node);
1124 struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev)
1126 struct sched_dl_entity *dl_se;
1127 struct task_struct *p;
1128 struct dl_rq *dl_rq;
1132 if (need_pull_dl_task(rq, prev)) {
1134 * This is OK, because current is on_cpu, which avoids it being
1135 * picked for load-balance and preemption/IRQs are still
1136 * disabled avoiding further scheduler activity on it and we're
1137 * being very careful to re-start the picking loop.
1139 lockdep_unpin_lock(&rq->lock);
1141 lockdep_pin_lock(&rq->lock);
1143 * pull_rt_task() can drop (and re-acquire) rq->lock; this
1144 * means a stop task can slip in, in which case we need to
1145 * re-start task selection.
1147 if (rq->stop && task_on_rq_queued(rq->stop))
1152 * When prev is DL, we may throttle it in put_prev_task().
1153 * So, we update time before we check for dl_nr_running.
1155 if (prev->sched_class == &dl_sched_class)
1158 if (unlikely(!dl_rq->dl_nr_running))
1161 put_prev_task(rq, prev);
1163 dl_se = pick_next_dl_entity(rq, dl_rq);
1166 p = dl_task_of(dl_se);
1167 p->se.exec_start = rq_clock_task(rq);
1169 /* Running task will never be pushed. */
1170 dequeue_pushable_dl_task(rq, p);
1172 if (hrtick_enabled(rq))
1173 start_hrtick_dl(rq, p);
1175 queue_push_tasks(rq);
1180 static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
1184 if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
1185 enqueue_pushable_dl_task(rq, p);
1188 static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
1193 * Even when we have runtime, update_curr_dl() might have resulted in us
1194 * not being the leftmost task anymore. In that case NEED_RESCHED will
1195 * be set and schedule() will start a new hrtick for the next task.
1197 if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 &&
1198 is_leftmost(p, &rq->dl))
1199 start_hrtick_dl(rq, p);
1202 static void task_fork_dl(struct task_struct *p)
1205 * SCHED_DEADLINE tasks cannot fork and this is achieved through
1210 static void task_dead_dl(struct task_struct *p)
1212 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
1215 * Since we are TASK_DEAD we won't slip out of the domain!
1217 raw_spin_lock_irq(&dl_b->lock);
1218 /* XXX we should retain the bw until 0-lag */
1219 dl_b->total_bw -= p->dl.dl_bw;
1220 raw_spin_unlock_irq(&dl_b->lock);
1223 static void set_curr_task_dl(struct rq *rq)
1225 struct task_struct *p = rq->curr;
1227 p->se.exec_start = rq_clock_task(rq);
1229 /* You can't push away the running task */
1230 dequeue_pushable_dl_task(rq, p);
1235 /* Only try algorithms three times */
1236 #define DL_MAX_TRIES 3
1238 static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
1240 if (!task_running(rq, p) &&
1241 cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
1247 * Return the earliest pushable rq's task, which is suitable to be executed
1248 * on the CPU, NULL otherwise:
1250 static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu)
1252 struct rb_node *next_node = rq->dl.pushable_dl_tasks_leftmost;
1253 struct task_struct *p = NULL;
1255 if (!has_pushable_dl_tasks(rq))
1260 p = rb_entry(next_node, struct task_struct, pushable_dl_tasks);
1262 if (pick_dl_task(rq, p, cpu))
1265 next_node = rb_next(next_node);
1272 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
1274 static int find_later_rq(struct task_struct *task)
1276 struct sched_domain *sd;
1277 struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl);
1278 int this_cpu = smp_processor_id();
1279 int best_cpu, cpu = task_cpu(task);
1281 /* Make sure the mask is initialized first */
1282 if (unlikely(!later_mask))
1285 if (task->nr_cpus_allowed == 1)
1289 * We have to consider system topology and task affinity
1290 * first, then we can look for a suitable cpu.
1292 best_cpu = cpudl_find(&task_rq(task)->rd->cpudl,
1298 * If we are here, some target has been found,
1299 * the most suitable of which is cached in best_cpu.
1300 * This is, among the runqueues where the current tasks
1301 * have later deadlines than the task's one, the rq
1302 * with the latest possible one.
1304 * Now we check how well this matches with task's
1305 * affinity and system topology.
1307 * The last cpu where the task run is our first
1308 * guess, since it is most likely cache-hot there.
1310 if (cpumask_test_cpu(cpu, later_mask))
1313 * Check if this_cpu is to be skipped (i.e., it is
1314 * not in the mask) or not.
1316 if (!cpumask_test_cpu(this_cpu, later_mask))
1320 for_each_domain(cpu, sd) {
1321 if (sd->flags & SD_WAKE_AFFINE) {
1324 * If possible, preempting this_cpu is
1325 * cheaper than migrating.
1327 if (this_cpu != -1 &&
1328 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1334 * Last chance: if best_cpu is valid and is
1335 * in the mask, that becomes our choice.
1337 if (best_cpu < nr_cpu_ids &&
1338 cpumask_test_cpu(best_cpu, sched_domain_span(sd))) {
1347 * At this point, all our guesses failed, we just return
1348 * 'something', and let the caller sort the things out.
1353 cpu = cpumask_any(later_mask);
1354 if (cpu < nr_cpu_ids)
1360 /* Locks the rq it finds */
1361 static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
1363 struct rq *later_rq = NULL;
1367 for (tries = 0; tries < DL_MAX_TRIES; tries++) {
1368 cpu = find_later_rq(task);
1370 if ((cpu == -1) || (cpu == rq->cpu))
1373 later_rq = cpu_rq(cpu);
1375 if (later_rq->dl.dl_nr_running &&
1376 !dl_time_before(task->dl.deadline,
1377 later_rq->dl.earliest_dl.curr)) {
1379 * Target rq has tasks of equal or earlier deadline,
1380 * retrying does not release any lock and is unlikely
1381 * to yield a different result.
1387 /* Retry if something changed. */
1388 if (double_lock_balance(rq, later_rq)) {
1389 if (unlikely(task_rq(task) != rq ||
1390 !cpumask_test_cpu(later_rq->cpu,
1391 &task->cpus_allowed) ||
1392 task_running(rq, task) ||
1393 !task_on_rq_queued(task))) {
1394 double_unlock_balance(rq, later_rq);
1401 * If the rq we found has no -deadline task, or
1402 * its earliest one has a later deadline than our
1403 * task, the rq is a good one.
1405 if (!later_rq->dl.dl_nr_running ||
1406 dl_time_before(task->dl.deadline,
1407 later_rq->dl.earliest_dl.curr))
1410 /* Otherwise we try again. */
1411 double_unlock_balance(rq, later_rq);
1418 static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
1420 struct task_struct *p;
1422 if (!has_pushable_dl_tasks(rq))
1425 p = rb_entry(rq->dl.pushable_dl_tasks_leftmost,
1426 struct task_struct, pushable_dl_tasks);
1428 BUG_ON(rq->cpu != task_cpu(p));
1429 BUG_ON(task_current(rq, p));
1430 BUG_ON(p->nr_cpus_allowed <= 1);
1432 BUG_ON(!task_on_rq_queued(p));
1433 BUG_ON(!dl_task(p));
1439 * See if the non running -deadline tasks on this rq
1440 * can be sent to some other CPU where they can preempt
1441 * and start executing.
1443 static int push_dl_task(struct rq *rq)
1445 struct task_struct *next_task;
1446 struct rq *later_rq;
1449 if (!rq->dl.overloaded)
1452 next_task = pick_next_pushable_dl_task(rq);
1457 if (unlikely(next_task == rq->curr)) {
1463 * If next_task preempts rq->curr, and rq->curr
1464 * can move away, it makes sense to just reschedule
1465 * without going further in pushing next_task.
1467 if (dl_task(rq->curr) &&
1468 dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
1469 rq->curr->nr_cpus_allowed > 1) {
1474 /* We might release rq lock */
1475 get_task_struct(next_task);
1477 /* Will lock the rq it'll find */
1478 later_rq = find_lock_later_rq(next_task, rq);
1480 struct task_struct *task;
1483 * We must check all this again, since
1484 * find_lock_later_rq releases rq->lock and it is
1485 * then possible that next_task has migrated.
1487 task = pick_next_pushable_dl_task(rq);
1488 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1490 * The task is still there. We don't try
1491 * again, some other cpu will pull it when ready.
1500 put_task_struct(next_task);
1505 deactivate_task(rq, next_task, 0);
1506 set_task_cpu(next_task, later_rq->cpu);
1507 activate_task(later_rq, next_task, 0);
1510 resched_curr(later_rq);
1512 double_unlock_balance(rq, later_rq);
1515 put_task_struct(next_task);
1520 static void push_dl_tasks(struct rq *rq)
1522 /* push_dl_task() will return true if it moved a -deadline task */
1523 while (push_dl_task(rq))
1527 static void pull_dl_task(struct rq *this_rq)
1529 int this_cpu = this_rq->cpu, cpu;
1530 struct task_struct *p;
1531 bool resched = false;
1533 u64 dmin = LONG_MAX;
1535 if (likely(!dl_overloaded(this_rq)))
1539 * Match the barrier from dl_set_overloaded; this guarantees that if we
1540 * see overloaded we must also see the dlo_mask bit.
1544 for_each_cpu(cpu, this_rq->rd->dlo_mask) {
1545 if (this_cpu == cpu)
1548 src_rq = cpu_rq(cpu);
1551 * It looks racy, abd it is! However, as in sched_rt.c,
1552 * we are fine with this.
1554 if (this_rq->dl.dl_nr_running &&
1555 dl_time_before(this_rq->dl.earliest_dl.curr,
1556 src_rq->dl.earliest_dl.next))
1559 /* Might drop this_rq->lock */
1560 double_lock_balance(this_rq, src_rq);
1563 * If there are no more pullable tasks on the
1564 * rq, we're done with it.
1566 if (src_rq->dl.dl_nr_running <= 1)
1569 p = pick_earliest_pushable_dl_task(src_rq, this_cpu);
1572 * We found a task to be pulled if:
1573 * - it preempts our current (if there's one),
1574 * - it will preempt the last one we pulled (if any).
1576 if (p && dl_time_before(p->dl.deadline, dmin) &&
1577 (!this_rq->dl.dl_nr_running ||
1578 dl_time_before(p->dl.deadline,
1579 this_rq->dl.earliest_dl.curr))) {
1580 WARN_ON(p == src_rq->curr);
1581 WARN_ON(!task_on_rq_queued(p));
1584 * Then we pull iff p has actually an earlier
1585 * deadline than the current task of its runqueue.
1587 if (dl_time_before(p->dl.deadline,
1588 src_rq->curr->dl.deadline))
1593 deactivate_task(src_rq, p, 0);
1594 set_task_cpu(p, this_cpu);
1595 activate_task(this_rq, p, 0);
1596 dmin = p->dl.deadline;
1598 /* Is there any other task even earlier? */
1601 double_unlock_balance(this_rq, src_rq);
1605 resched_curr(this_rq);
1609 * Since the task is not running and a reschedule is not going to happen
1610 * anytime soon on its runqueue, we try pushing it away now.
1612 static void task_woken_dl(struct rq *rq, struct task_struct *p)
1614 if (!task_running(rq, p) &&
1615 !test_tsk_need_resched(rq->curr) &&
1616 p->nr_cpus_allowed > 1 &&
1617 dl_task(rq->curr) &&
1618 (rq->curr->nr_cpus_allowed < 2 ||
1619 !dl_entity_preempt(&p->dl, &rq->curr->dl))) {
1624 static void set_cpus_allowed_dl(struct task_struct *p,
1625 const struct cpumask *new_mask)
1627 struct root_domain *src_rd;
1630 BUG_ON(!dl_task(p));
1635 * Migrating a SCHED_DEADLINE task between exclusive
1636 * cpusets (different root_domains) entails a bandwidth
1637 * update. We already made space for us in the destination
1638 * domain (see cpuset_can_attach()).
1640 if (!cpumask_intersects(src_rd->span, new_mask)) {
1641 struct dl_bw *src_dl_b;
1643 src_dl_b = dl_bw_of(cpu_of(rq));
1645 * We now free resources of the root_domain we are migrating
1646 * off. In the worst case, sched_setattr() may temporary fail
1647 * until we complete the update.
1649 raw_spin_lock(&src_dl_b->lock);
1650 __dl_clear(src_dl_b, p->dl.dl_bw);
1651 raw_spin_unlock(&src_dl_b->lock);
1654 set_cpus_allowed_common(p, new_mask);
1657 /* Assumes rq->lock is held */
1658 static void rq_online_dl(struct rq *rq)
1660 if (rq->dl.overloaded)
1661 dl_set_overload(rq);
1663 cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
1664 if (rq->dl.dl_nr_running > 0)
1665 cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr, 1);
1668 /* Assumes rq->lock is held */
1669 static void rq_offline_dl(struct rq *rq)
1671 if (rq->dl.overloaded)
1672 dl_clear_overload(rq);
1674 cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
1675 cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
1678 void __init init_sched_dl_class(void)
1682 for_each_possible_cpu(i)
1683 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
1684 GFP_KERNEL, cpu_to_node(i));
1687 #endif /* CONFIG_SMP */
1689 static void switched_from_dl(struct rq *rq, struct task_struct *p)
1692 * Start the deadline timer; if we switch back to dl before this we'll
1693 * continue consuming our current CBS slice. If we stay outside of
1694 * SCHED_DEADLINE until the deadline passes, the timer will reset the
1697 if (!start_dl_timer(p))
1698 __dl_clear_params(p);
1701 * Since this might be the only -deadline task on the rq,
1702 * this is the right place to try to pull some other one
1703 * from an overloaded cpu, if any.
1705 if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
1708 queue_pull_task(rq);
1712 * When switching to -deadline, we may overload the rq, then
1713 * we try to push someone off, if possible.
1715 static void switched_to_dl(struct rq *rq, struct task_struct *p)
1717 if (dl_time_before(p->dl.deadline, rq_clock(rq)))
1718 setup_new_dl_entity(&p->dl, &p->dl);
1720 if (task_on_rq_queued(p) && rq->curr != p) {
1722 if (p->nr_cpus_allowed > 1 && rq->dl.overloaded)
1723 queue_push_tasks(rq);
1725 if (dl_task(rq->curr))
1726 check_preempt_curr_dl(rq, p, 0);
1734 * If the scheduling parameters of a -deadline task changed,
1735 * a push or pull operation might be needed.
1737 static void prio_changed_dl(struct rq *rq, struct task_struct *p,
1740 if (task_on_rq_queued(p) || rq->curr == p) {
1743 * This might be too much, but unfortunately
1744 * we don't have the old deadline value, and
1745 * we can't argue if the task is increasing
1746 * or lowering its prio, so...
1748 if (!rq->dl.overloaded)
1749 queue_pull_task(rq);
1752 * If we now have a earlier deadline task than p,
1753 * then reschedule, provided p is still on this
1756 if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline))
1760 * Again, we don't know if p has a earlier
1761 * or later deadline, so let's blindly set a
1762 * (maybe not needed) rescheduling point.
1765 #endif /* CONFIG_SMP */
1769 const struct sched_class dl_sched_class = {
1770 .next = &rt_sched_class,
1771 .enqueue_task = enqueue_task_dl,
1772 .dequeue_task = dequeue_task_dl,
1773 .yield_task = yield_task_dl,
1775 .check_preempt_curr = check_preempt_curr_dl,
1777 .pick_next_task = pick_next_task_dl,
1778 .put_prev_task = put_prev_task_dl,
1781 .select_task_rq = select_task_rq_dl,
1782 .set_cpus_allowed = set_cpus_allowed_dl,
1783 .rq_online = rq_online_dl,
1784 .rq_offline = rq_offline_dl,
1785 .task_woken = task_woken_dl,
1788 .set_curr_task = set_curr_task_dl,
1789 .task_tick = task_tick_dl,
1790 .task_fork = task_fork_dl,
1791 .task_dead = task_dead_dl,
1793 .prio_changed = prio_changed_dl,
1794 .switched_from = switched_from_dl,
1795 .switched_to = switched_to_dl,
1797 .update_curr = update_curr_dl,
1800 #ifdef CONFIG_SCHED_DEBUG
1801 extern void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq);
1803 void print_dl_stats(struct seq_file *m, int cpu)
1805 print_dl_rq(m, cpu, &cpu_rq(cpu)->dl);
1807 #endif /* CONFIG_SCHED_DEBUG */