1 // SPDX-License-Identifier: GPL-2.0
3 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
9 #include <linux/slab.h>
10 #include <linux/irq_work.h>
12 int sched_rr_timeslice = RR_TIMESLICE;
13 int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
15 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
17 struct rt_bandwidth def_rt_bandwidth;
19 static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
21 struct rt_bandwidth *rt_b =
22 container_of(timer, struct rt_bandwidth, rt_period_timer);
26 raw_spin_lock(&rt_b->rt_runtime_lock);
28 overrun = hrtimer_forward_now(timer, rt_b->rt_period);
32 raw_spin_unlock(&rt_b->rt_runtime_lock);
33 idle = do_sched_rt_period_timer(rt_b, overrun);
34 raw_spin_lock(&rt_b->rt_runtime_lock);
37 rt_b->rt_period_active = 0;
38 raw_spin_unlock(&rt_b->rt_runtime_lock);
40 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
43 void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
45 rt_b->rt_period = ns_to_ktime(period);
46 rt_b->rt_runtime = runtime;
48 raw_spin_lock_init(&rt_b->rt_runtime_lock);
50 hrtimer_init(&rt_b->rt_period_timer,
51 CLOCK_MONOTONIC, HRTIMER_MODE_REL);
52 rt_b->rt_period_timer.function = sched_rt_period_timer;
55 static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
57 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
60 raw_spin_lock(&rt_b->rt_runtime_lock);
61 if (!rt_b->rt_period_active) {
62 rt_b->rt_period_active = 1;
64 * SCHED_DEADLINE updates the bandwidth, as a run away
65 * RT task with a DL task could hog a CPU. But DL does
66 * not reset the period. If a deadline task was running
67 * without an RT task running, it can cause RT tasks to
68 * throttle when they start up. Kick the timer right away
69 * to update the period.
71 hrtimer_forward_now(&rt_b->rt_period_timer, ns_to_ktime(0));
72 hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED);
74 raw_spin_unlock(&rt_b->rt_runtime_lock);
77 void init_rt_rq(struct rt_rq *rt_rq)
79 struct rt_prio_array *array;
82 array = &rt_rq->active;
83 for (i = 0; i < MAX_RT_PRIO; i++) {
84 INIT_LIST_HEAD(array->queue + i);
85 __clear_bit(i, array->bitmap);
87 /* delimiter for bitsearch: */
88 __set_bit(MAX_RT_PRIO, array->bitmap);
90 #if defined CONFIG_SMP
91 rt_rq->highest_prio.curr = MAX_RT_PRIO;
92 rt_rq->highest_prio.next = MAX_RT_PRIO;
93 rt_rq->rt_nr_migratory = 0;
94 rt_rq->overloaded = 0;
95 plist_head_init(&rt_rq->pushable_tasks);
96 #endif /* CONFIG_SMP */
97 /* We start is dequeued state, because no RT tasks are queued */
101 rt_rq->rt_throttled = 0;
102 rt_rq->rt_runtime = 0;
103 raw_spin_lock_init(&rt_rq->rt_runtime_lock);
106 #ifdef CONFIG_RT_GROUP_SCHED
107 static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
109 hrtimer_cancel(&rt_b->rt_period_timer);
112 #define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
114 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
116 #ifdef CONFIG_SCHED_DEBUG
117 WARN_ON_ONCE(!rt_entity_is_task(rt_se));
119 return container_of(rt_se, struct task_struct, rt);
122 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
127 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
132 static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
134 struct rt_rq *rt_rq = rt_se->rt_rq;
139 void free_rt_sched_group(struct task_group *tg)
144 destroy_rt_bandwidth(&tg->rt_bandwidth);
146 for_each_possible_cpu(i) {
157 void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
158 struct sched_rt_entity *rt_se, int cpu,
159 struct sched_rt_entity *parent)
161 struct rq *rq = cpu_rq(cpu);
163 rt_rq->highest_prio.curr = MAX_RT_PRIO;
164 rt_rq->rt_nr_boosted = 0;
168 tg->rt_rq[cpu] = rt_rq;
169 tg->rt_se[cpu] = rt_se;
175 rt_se->rt_rq = &rq->rt;
177 rt_se->rt_rq = parent->my_q;
180 rt_se->parent = parent;
181 INIT_LIST_HEAD(&rt_se->run_list);
184 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
187 struct sched_rt_entity *rt_se;
190 tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
193 tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
197 init_rt_bandwidth(&tg->rt_bandwidth,
198 ktime_to_ns(def_rt_bandwidth.rt_period), 0);
200 for_each_possible_cpu(i) {
201 rt_rq = kzalloc_node(sizeof(struct rt_rq),
202 GFP_KERNEL, cpu_to_node(i));
206 rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
207 GFP_KERNEL, cpu_to_node(i));
212 rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
213 init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
224 #else /* CONFIG_RT_GROUP_SCHED */
226 #define rt_entity_is_task(rt_se) (1)
228 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
230 return container_of(rt_se, struct task_struct, rt);
233 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
235 return container_of(rt_rq, struct rq, rt);
238 static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
240 struct task_struct *p = rt_task_of(rt_se);
245 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
247 struct rq *rq = rq_of_rt_se(rt_se);
252 void free_rt_sched_group(struct task_group *tg) { }
254 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
258 #endif /* CONFIG_RT_GROUP_SCHED */
262 static void pull_rt_task(struct rq *this_rq);
264 static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
266 /* Try to pull RT tasks here if we lower this rq's prio */
267 return rq->rt.highest_prio.curr > prev->prio;
270 static inline int rt_overloaded(struct rq *rq)
272 return atomic_read(&rq->rd->rto_count);
275 static inline void rt_set_overload(struct rq *rq)
280 cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
282 * Make sure the mask is visible before we set
283 * the overload count. That is checked to determine
284 * if we should look at the mask. It would be a shame
285 * if we looked at the mask, but the mask was not
288 * Matched by the barrier in pull_rt_task().
291 atomic_inc(&rq->rd->rto_count);
294 static inline void rt_clear_overload(struct rq *rq)
299 /* the order here really doesn't matter */
300 atomic_dec(&rq->rd->rto_count);
301 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
304 static void update_rt_migration(struct rt_rq *rt_rq)
306 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
307 if (!rt_rq->overloaded) {
308 rt_set_overload(rq_of_rt_rq(rt_rq));
309 rt_rq->overloaded = 1;
311 } else if (rt_rq->overloaded) {
312 rt_clear_overload(rq_of_rt_rq(rt_rq));
313 rt_rq->overloaded = 0;
317 static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
319 struct task_struct *p;
321 if (!rt_entity_is_task(rt_se))
324 p = rt_task_of(rt_se);
325 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
327 rt_rq->rt_nr_total++;
328 if (p->nr_cpus_allowed > 1)
329 rt_rq->rt_nr_migratory++;
331 update_rt_migration(rt_rq);
334 static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
336 struct task_struct *p;
338 if (!rt_entity_is_task(rt_se))
341 p = rt_task_of(rt_se);
342 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
344 rt_rq->rt_nr_total--;
345 if (p->nr_cpus_allowed > 1)
346 rt_rq->rt_nr_migratory--;
348 update_rt_migration(rt_rq);
351 static inline int has_pushable_tasks(struct rq *rq)
353 return !plist_head_empty(&rq->rt.pushable_tasks);
356 static DEFINE_PER_CPU(struct callback_head, rt_push_head);
357 static DEFINE_PER_CPU(struct callback_head, rt_pull_head);
359 static void push_rt_tasks(struct rq *);
360 static void pull_rt_task(struct rq *);
362 static inline void queue_push_tasks(struct rq *rq)
364 if (!has_pushable_tasks(rq))
367 queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
370 static inline void queue_pull_task(struct rq *rq)
372 queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
375 static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
377 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
378 plist_node_init(&p->pushable_tasks, p->prio);
379 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
381 /* Update the highest prio pushable task */
382 if (p->prio < rq->rt.highest_prio.next)
383 rq->rt.highest_prio.next = p->prio;
386 static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
388 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
390 /* Update the new highest prio pushable task */
391 if (has_pushable_tasks(rq)) {
392 p = plist_first_entry(&rq->rt.pushable_tasks,
393 struct task_struct, pushable_tasks);
394 rq->rt.highest_prio.next = p->prio;
396 rq->rt.highest_prio.next = MAX_RT_PRIO;
401 static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
405 static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
410 void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
415 void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
419 static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
424 static inline void pull_rt_task(struct rq *this_rq)
428 static inline void queue_push_tasks(struct rq *rq)
431 #endif /* CONFIG_SMP */
433 static void enqueue_top_rt_rq(struct rt_rq *rt_rq);
434 static void dequeue_top_rt_rq(struct rt_rq *rt_rq);
436 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
441 #ifdef CONFIG_RT_GROUP_SCHED
443 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
448 return rt_rq->rt_runtime;
451 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
453 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
456 typedef struct task_group *rt_rq_iter_t;
458 static inline struct task_group *next_task_group(struct task_group *tg)
461 tg = list_entry_rcu(tg->list.next,
462 typeof(struct task_group), list);
463 } while (&tg->list != &task_groups && task_group_is_autogroup(tg));
465 if (&tg->list == &task_groups)
471 #define for_each_rt_rq(rt_rq, iter, rq) \
472 for (iter = container_of(&task_groups, typeof(*iter), list); \
473 (iter = next_task_group(iter)) && \
474 (rt_rq = iter->rt_rq[cpu_of(rq)]);)
476 #define for_each_sched_rt_entity(rt_se) \
477 for (; rt_se; rt_se = rt_se->parent)
479 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
484 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
485 static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
487 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
489 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
490 struct rq *rq = rq_of_rt_rq(rt_rq);
491 struct sched_rt_entity *rt_se;
493 int cpu = cpu_of(rq);
495 rt_se = rt_rq->tg->rt_se[cpu];
497 if (rt_rq->rt_nr_running) {
499 enqueue_top_rt_rq(rt_rq);
500 else if (!on_rt_rq(rt_se))
501 enqueue_rt_entity(rt_se, 0);
503 if (rt_rq->highest_prio.curr < curr->prio)
508 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
510 struct sched_rt_entity *rt_se;
511 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
513 rt_se = rt_rq->tg->rt_se[cpu];
516 dequeue_top_rt_rq(rt_rq);
517 else if (on_rt_rq(rt_se))
518 dequeue_rt_entity(rt_se, 0);
521 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
523 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
526 static int rt_se_boosted(struct sched_rt_entity *rt_se)
528 struct rt_rq *rt_rq = group_rt_rq(rt_se);
529 struct task_struct *p;
532 return !!rt_rq->rt_nr_boosted;
534 p = rt_task_of(rt_se);
535 return p->prio != p->normal_prio;
539 static inline const struct cpumask *sched_rt_period_mask(void)
541 return this_rq()->rd->span;
544 static inline const struct cpumask *sched_rt_period_mask(void)
546 return cpu_online_mask;
551 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
553 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
556 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
558 return &rt_rq->tg->rt_bandwidth;
561 #else /* !CONFIG_RT_GROUP_SCHED */
563 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
565 return rt_rq->rt_runtime;
568 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
570 return ktime_to_ns(def_rt_bandwidth.rt_period);
573 typedef struct rt_rq *rt_rq_iter_t;
575 #define for_each_rt_rq(rt_rq, iter, rq) \
576 for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
578 #define for_each_sched_rt_entity(rt_se) \
579 for (; rt_se; rt_se = NULL)
581 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
586 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
588 struct rq *rq = rq_of_rt_rq(rt_rq);
590 if (!rt_rq->rt_nr_running)
593 enqueue_top_rt_rq(rt_rq);
597 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
599 dequeue_top_rt_rq(rt_rq);
602 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
604 return rt_rq->rt_throttled;
607 static inline const struct cpumask *sched_rt_period_mask(void)
609 return cpu_online_mask;
613 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
615 return &cpu_rq(cpu)->rt;
618 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
620 return &def_rt_bandwidth;
623 #endif /* CONFIG_RT_GROUP_SCHED */
625 bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
627 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
629 return (hrtimer_active(&rt_b->rt_period_timer) ||
630 rt_rq->rt_time < rt_b->rt_runtime);
635 * We ran out of runtime, see if we can borrow some from our neighbours.
637 static void do_balance_runtime(struct rt_rq *rt_rq)
639 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
640 struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;
644 weight = cpumask_weight(rd->span);
646 raw_spin_lock(&rt_b->rt_runtime_lock);
647 rt_period = ktime_to_ns(rt_b->rt_period);
648 for_each_cpu(i, rd->span) {
649 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
655 raw_spin_lock(&iter->rt_runtime_lock);
657 * Either all rqs have inf runtime and there's nothing to steal
658 * or __disable_runtime() below sets a specific rq to inf to
659 * indicate its been disabled and disalow stealing.
661 if (iter->rt_runtime == RUNTIME_INF)
665 * From runqueues with spare time, take 1/n part of their
666 * spare time, but no more than our period.
668 diff = iter->rt_runtime - iter->rt_time;
670 diff = div_u64((u64)diff, weight);
671 if (rt_rq->rt_runtime + diff > rt_period)
672 diff = rt_period - rt_rq->rt_runtime;
673 iter->rt_runtime -= diff;
674 rt_rq->rt_runtime += diff;
675 if (rt_rq->rt_runtime == rt_period) {
676 raw_spin_unlock(&iter->rt_runtime_lock);
681 raw_spin_unlock(&iter->rt_runtime_lock);
683 raw_spin_unlock(&rt_b->rt_runtime_lock);
687 * Ensure this RQ takes back all the runtime it lend to its neighbours.
689 static void __disable_runtime(struct rq *rq)
691 struct root_domain *rd = rq->rd;
695 if (unlikely(!scheduler_running))
698 for_each_rt_rq(rt_rq, iter, rq) {
699 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
703 raw_spin_lock(&rt_b->rt_runtime_lock);
704 raw_spin_lock(&rt_rq->rt_runtime_lock);
706 * Either we're all inf and nobody needs to borrow, or we're
707 * already disabled and thus have nothing to do, or we have
708 * exactly the right amount of runtime to take out.
710 if (rt_rq->rt_runtime == RUNTIME_INF ||
711 rt_rq->rt_runtime == rt_b->rt_runtime)
713 raw_spin_unlock(&rt_rq->rt_runtime_lock);
716 * Calculate the difference between what we started out with
717 * and what we current have, that's the amount of runtime
718 * we lend and now have to reclaim.
720 want = rt_b->rt_runtime - rt_rq->rt_runtime;
723 * Greedy reclaim, take back as much as we can.
725 for_each_cpu(i, rd->span) {
726 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
730 * Can't reclaim from ourselves or disabled runqueues.
732 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
735 raw_spin_lock(&iter->rt_runtime_lock);
737 diff = min_t(s64, iter->rt_runtime, want);
738 iter->rt_runtime -= diff;
741 iter->rt_runtime -= want;
744 raw_spin_unlock(&iter->rt_runtime_lock);
750 raw_spin_lock(&rt_rq->rt_runtime_lock);
752 * We cannot be left wanting - that would mean some runtime
753 * leaked out of the system.
758 * Disable all the borrow logic by pretending we have inf
759 * runtime - in which case borrowing doesn't make sense.
761 rt_rq->rt_runtime = RUNTIME_INF;
762 rt_rq->rt_throttled = 0;
763 raw_spin_unlock(&rt_rq->rt_runtime_lock);
764 raw_spin_unlock(&rt_b->rt_runtime_lock);
766 /* Make rt_rq available for pick_next_task() */
767 sched_rt_rq_enqueue(rt_rq);
771 static void __enable_runtime(struct rq *rq)
776 if (unlikely(!scheduler_running))
780 * Reset each runqueue's bandwidth settings
782 for_each_rt_rq(rt_rq, iter, rq) {
783 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
785 raw_spin_lock(&rt_b->rt_runtime_lock);
786 raw_spin_lock(&rt_rq->rt_runtime_lock);
787 rt_rq->rt_runtime = rt_b->rt_runtime;
789 rt_rq->rt_throttled = 0;
790 raw_spin_unlock(&rt_rq->rt_runtime_lock);
791 raw_spin_unlock(&rt_b->rt_runtime_lock);
795 static void balance_runtime(struct rt_rq *rt_rq)
797 if (!sched_feat(RT_RUNTIME_SHARE))
800 if (rt_rq->rt_time > rt_rq->rt_runtime) {
801 raw_spin_unlock(&rt_rq->rt_runtime_lock);
802 do_balance_runtime(rt_rq);
803 raw_spin_lock(&rt_rq->rt_runtime_lock);
806 #else /* !CONFIG_SMP */
807 static inline void balance_runtime(struct rt_rq *rt_rq) {}
808 #endif /* CONFIG_SMP */
810 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
812 int i, idle = 1, throttled = 0;
813 const struct cpumask *span;
815 span = sched_rt_period_mask();
816 #ifdef CONFIG_RT_GROUP_SCHED
818 * FIXME: isolated CPUs should really leave the root task group,
819 * whether they are isolcpus or were isolated via cpusets, lest
820 * the timer run on a CPU which does not service all runqueues,
821 * potentially leaving other CPUs indefinitely throttled. If
822 * isolation is really required, the user will turn the throttle
823 * off to kill the perturbations it causes anyway. Meanwhile,
824 * this maintains functionality for boot and/or troubleshooting.
826 if (rt_b == &root_task_group.rt_bandwidth)
827 span = cpu_online_mask;
829 for_each_cpu(i, span) {
831 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
832 struct rq *rq = rq_of_rt_rq(rt_rq);
836 * When span == cpu_online_mask, taking each rq->lock
837 * can be time-consuming. Try to avoid it when possible.
839 raw_spin_lock(&rt_rq->rt_runtime_lock);
840 skip = !rt_rq->rt_time && !rt_rq->rt_nr_running;
841 raw_spin_unlock(&rt_rq->rt_runtime_lock);
845 raw_spin_lock(&rq->lock);
846 if (rt_rq->rt_time) {
849 raw_spin_lock(&rt_rq->rt_runtime_lock);
850 if (rt_rq->rt_throttled)
851 balance_runtime(rt_rq);
852 runtime = rt_rq->rt_runtime;
853 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
854 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
855 rt_rq->rt_throttled = 0;
859 * When we're idle and a woken (rt) task is
860 * throttled check_preempt_curr() will set
861 * skip_update and the time between the wakeup
862 * and this unthrottle will get accounted as
865 if (rt_rq->rt_nr_running && rq->curr == rq->idle)
866 rq_clock_skip_update(rq, false);
868 if (rt_rq->rt_time || rt_rq->rt_nr_running)
870 raw_spin_unlock(&rt_rq->rt_runtime_lock);
871 } else if (rt_rq->rt_nr_running) {
873 if (!rt_rq_throttled(rt_rq))
876 if (rt_rq->rt_throttled)
880 sched_rt_rq_enqueue(rt_rq);
881 raw_spin_unlock(&rq->lock);
884 if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
890 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
892 #ifdef CONFIG_RT_GROUP_SCHED
893 struct rt_rq *rt_rq = group_rt_rq(rt_se);
896 return rt_rq->highest_prio.curr;
899 return rt_task_of(rt_se)->prio;
902 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
904 u64 runtime = sched_rt_runtime(rt_rq);
906 if (rt_rq->rt_throttled)
907 return rt_rq_throttled(rt_rq);
909 if (runtime >= sched_rt_period(rt_rq))
912 balance_runtime(rt_rq);
913 runtime = sched_rt_runtime(rt_rq);
914 if (runtime == RUNTIME_INF)
917 if (rt_rq->rt_time > runtime) {
918 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
921 * Don't actually throttle groups that have no runtime assigned
922 * but accrue some time due to boosting.
924 if (likely(rt_b->rt_runtime)) {
925 rt_rq->rt_throttled = 1;
926 printk_deferred_once("sched: RT throttling activated\n");
929 * In case we did anyway, make it go away,
930 * replenishment is a joke, since it will replenish us
936 if (rt_rq_throttled(rt_rq)) {
937 sched_rt_rq_dequeue(rt_rq);
946 * Update the current task's runtime statistics. Skip current tasks that
947 * are not in our scheduling class.
949 static void update_curr_rt(struct rq *rq)
951 struct task_struct *curr = rq->curr;
952 struct sched_rt_entity *rt_se = &curr->rt;
955 if (curr->sched_class != &rt_sched_class)
958 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
959 if (unlikely((s64)delta_exec <= 0))
962 /* Kick cpufreq (see the comment in kernel/sched/sched.h). */
963 cpufreq_update_util(rq, SCHED_CPUFREQ_RT);
965 schedstat_set(curr->se.statistics.exec_max,
966 max(curr->se.statistics.exec_max, delta_exec));
968 curr->se.sum_exec_runtime += delta_exec;
969 account_group_exec_runtime(curr, delta_exec);
971 curr->se.exec_start = rq_clock_task(rq);
972 cgroup_account_cputime(curr, delta_exec);
974 sched_rt_avg_update(rq, delta_exec);
976 if (!rt_bandwidth_enabled())
979 for_each_sched_rt_entity(rt_se) {
980 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
982 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
983 raw_spin_lock(&rt_rq->rt_runtime_lock);
984 rt_rq->rt_time += delta_exec;
985 if (sched_rt_runtime_exceeded(rt_rq))
987 raw_spin_unlock(&rt_rq->rt_runtime_lock);
993 dequeue_top_rt_rq(struct rt_rq *rt_rq)
995 struct rq *rq = rq_of_rt_rq(rt_rq);
997 BUG_ON(&rq->rt != rt_rq);
999 if (!rt_rq->rt_queued)
1002 BUG_ON(!rq->nr_running);
1004 sub_nr_running(rq, rt_rq->rt_nr_running);
1005 rt_rq->rt_queued = 0;
1009 enqueue_top_rt_rq(struct rt_rq *rt_rq)
1011 struct rq *rq = rq_of_rt_rq(rt_rq);
1013 BUG_ON(&rq->rt != rt_rq);
1015 if (rt_rq->rt_queued)
1017 if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running)
1020 add_nr_running(rq, rt_rq->rt_nr_running);
1021 rt_rq->rt_queued = 1;
1024 #if defined CONFIG_SMP
1027 inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1029 struct rq *rq = rq_of_rt_rq(rt_rq);
1031 #ifdef CONFIG_RT_GROUP_SCHED
1033 * Change rq's cpupri only if rt_rq is the top queue.
1035 if (&rq->rt != rt_rq)
1038 if (rq->online && prio < prev_prio)
1039 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
1043 dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1045 struct rq *rq = rq_of_rt_rq(rt_rq);
1047 #ifdef CONFIG_RT_GROUP_SCHED
1049 * Change rq's cpupri only if rt_rq is the top queue.
1051 if (&rq->rt != rt_rq)
1054 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
1055 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
1058 #else /* CONFIG_SMP */
1061 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1063 void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1065 #endif /* CONFIG_SMP */
1067 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
1069 inc_rt_prio(struct rt_rq *rt_rq, int prio)
1071 int prev_prio = rt_rq->highest_prio.curr;
1073 if (prio < prev_prio)
1074 rt_rq->highest_prio.curr = prio;
1076 inc_rt_prio_smp(rt_rq, prio, prev_prio);
1080 dec_rt_prio(struct rt_rq *rt_rq, int prio)
1082 int prev_prio = rt_rq->highest_prio.curr;
1084 if (rt_rq->rt_nr_running) {
1086 WARN_ON(prio < prev_prio);
1089 * This may have been our highest task, and therefore
1090 * we may have some recomputation to do
1092 if (prio == prev_prio) {
1093 struct rt_prio_array *array = &rt_rq->active;
1095 rt_rq->highest_prio.curr =
1096 sched_find_first_bit(array->bitmap);
1100 rt_rq->highest_prio.curr = MAX_RT_PRIO;
1102 dec_rt_prio_smp(rt_rq, prio, prev_prio);
1107 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
1108 static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
1110 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
1112 #ifdef CONFIG_RT_GROUP_SCHED
1115 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1117 if (rt_se_boosted(rt_se))
1118 rt_rq->rt_nr_boosted++;
1121 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
1125 dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1127 if (rt_se_boosted(rt_se))
1128 rt_rq->rt_nr_boosted--;
1130 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
1133 #else /* CONFIG_RT_GROUP_SCHED */
1136 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1138 start_rt_bandwidth(&def_rt_bandwidth);
1142 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1144 #endif /* CONFIG_RT_GROUP_SCHED */
1147 unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
1149 struct rt_rq *group_rq = group_rt_rq(rt_se);
1152 return group_rq->rt_nr_running;
1158 unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se)
1160 struct rt_rq *group_rq = group_rt_rq(rt_se);
1161 struct task_struct *tsk;
1164 return group_rq->rr_nr_running;
1166 tsk = rt_task_of(rt_se);
1168 return (tsk->policy == SCHED_RR) ? 1 : 0;
1172 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1174 int prio = rt_se_prio(rt_se);
1176 WARN_ON(!rt_prio(prio));
1177 rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
1178 rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se);
1180 inc_rt_prio(rt_rq, prio);
1181 inc_rt_migration(rt_se, rt_rq);
1182 inc_rt_group(rt_se, rt_rq);
1186 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1188 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
1189 WARN_ON(!rt_rq->rt_nr_running);
1190 rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
1191 rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se);
1193 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
1194 dec_rt_migration(rt_se, rt_rq);
1195 dec_rt_group(rt_se, rt_rq);
1199 * Change rt_se->run_list location unless SAVE && !MOVE
1201 * assumes ENQUEUE/DEQUEUE flags match
1203 static inline bool move_entity(unsigned int flags)
1205 if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE)
1211 static void __delist_rt_entity(struct sched_rt_entity *rt_se, struct rt_prio_array *array)
1213 list_del_init(&rt_se->run_list);
1215 if (list_empty(array->queue + rt_se_prio(rt_se)))
1216 __clear_bit(rt_se_prio(rt_se), array->bitmap);
1221 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1223 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1224 struct rt_prio_array *array = &rt_rq->active;
1225 struct rt_rq *group_rq = group_rt_rq(rt_se);
1226 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1229 * Don't enqueue the group if its throttled, or when empty.
1230 * The latter is a consequence of the former when a child group
1231 * get throttled and the current group doesn't have any other
1234 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running)) {
1236 __delist_rt_entity(rt_se, array);
1240 if (move_entity(flags)) {
1241 WARN_ON_ONCE(rt_se->on_list);
1242 if (flags & ENQUEUE_HEAD)
1243 list_add(&rt_se->run_list, queue);
1245 list_add_tail(&rt_se->run_list, queue);
1247 __set_bit(rt_se_prio(rt_se), array->bitmap);
1252 inc_rt_tasks(rt_se, rt_rq);
1255 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1257 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1258 struct rt_prio_array *array = &rt_rq->active;
1260 if (move_entity(flags)) {
1261 WARN_ON_ONCE(!rt_se->on_list);
1262 __delist_rt_entity(rt_se, array);
1266 dec_rt_tasks(rt_se, rt_rq);
1270 * Because the prio of an upper entry depends on the lower
1271 * entries, we must remove entries top - down.
1273 static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags)
1275 struct sched_rt_entity *back = NULL;
1277 for_each_sched_rt_entity(rt_se) {
1282 dequeue_top_rt_rq(rt_rq_of_se(back));
1284 for (rt_se = back; rt_se; rt_se = rt_se->back) {
1285 if (on_rt_rq(rt_se))
1286 __dequeue_rt_entity(rt_se, flags);
1290 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1292 struct rq *rq = rq_of_rt_se(rt_se);
1294 dequeue_rt_stack(rt_se, flags);
1295 for_each_sched_rt_entity(rt_se)
1296 __enqueue_rt_entity(rt_se, flags);
1297 enqueue_top_rt_rq(&rq->rt);
1300 static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1302 struct rq *rq = rq_of_rt_se(rt_se);
1304 dequeue_rt_stack(rt_se, flags);
1306 for_each_sched_rt_entity(rt_se) {
1307 struct rt_rq *rt_rq = group_rt_rq(rt_se);
1309 if (rt_rq && rt_rq->rt_nr_running)
1310 __enqueue_rt_entity(rt_se, flags);
1312 enqueue_top_rt_rq(&rq->rt);
1316 * Adding/removing a task to/from a priority array:
1319 enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1321 struct sched_rt_entity *rt_se = &p->rt;
1323 if (flags & ENQUEUE_WAKEUP)
1326 enqueue_rt_entity(rt_se, flags);
1328 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1329 enqueue_pushable_task(rq, p);
1332 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1334 struct sched_rt_entity *rt_se = &p->rt;
1337 dequeue_rt_entity(rt_se, flags);
1339 dequeue_pushable_task(rq, p);
1343 * Put task to the head or the end of the run list without the overhead of
1344 * dequeue followed by enqueue.
1347 requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
1349 if (on_rt_rq(rt_se)) {
1350 struct rt_prio_array *array = &rt_rq->active;
1351 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1354 list_move(&rt_se->run_list, queue);
1356 list_move_tail(&rt_se->run_list, queue);
1360 static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
1362 struct sched_rt_entity *rt_se = &p->rt;
1363 struct rt_rq *rt_rq;
1365 for_each_sched_rt_entity(rt_se) {
1366 rt_rq = rt_rq_of_se(rt_se);
1367 requeue_rt_entity(rt_rq, rt_se, head);
1371 static void yield_task_rt(struct rq *rq)
1373 requeue_task_rt(rq, rq->curr, 0);
1377 static int find_lowest_rq(struct task_struct *task);
1380 select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
1382 struct task_struct *curr;
1385 /* For anything but wake ups, just return the task_cpu */
1386 if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
1392 curr = READ_ONCE(rq->curr); /* unlocked access */
1395 * If the current task on @p's runqueue is an RT task, then
1396 * try to see if we can wake this RT task up on another
1397 * runqueue. Otherwise simply start this RT task
1398 * on its current runqueue.
1400 * We want to avoid overloading runqueues. If the woken
1401 * task is a higher priority, then it will stay on this CPU
1402 * and the lower prio task should be moved to another CPU.
1403 * Even though this will probably make the lower prio task
1404 * lose its cache, we do not want to bounce a higher task
1405 * around just because it gave up its CPU, perhaps for a
1408 * For equal prio tasks, we just let the scheduler sort it out.
1410 * Otherwise, just let it ride on the affined RQ and the
1411 * post-schedule router will push the preempted task away
1413 * This test is optimistic, if we get it wrong the load-balancer
1414 * will have to sort it out.
1416 if (curr && unlikely(rt_task(curr)) &&
1417 (curr->nr_cpus_allowed < 2 ||
1418 curr->prio <= p->prio)) {
1419 int target = find_lowest_rq(p);
1422 * Don't bother moving it if the destination CPU is
1423 * not running a lower priority task.
1426 p->prio < cpu_rq(target)->rt.highest_prio.curr)
1435 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1438 * Current can't be migrated, useless to reschedule,
1439 * let's hope p can move out.
1441 if (rq->curr->nr_cpus_allowed == 1 ||
1442 !cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1446 * p is migratable, so let's not schedule it and
1447 * see if it is pushed or pulled somewhere else.
1449 if (p->nr_cpus_allowed != 1
1450 && cpupri_find(&rq->rd->cpupri, p, NULL))
1454 * There appears to be other cpus that can accept
1455 * current and none to run 'p', so lets reschedule
1456 * to try and push current away:
1458 requeue_task_rt(rq, p, 1);
1462 #endif /* CONFIG_SMP */
1465 * Preempt the current task with a newly woken task if needed:
1467 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1469 if (p->prio < rq->curr->prio) {
1478 * - the newly woken task is of equal priority to the current task
1479 * - the newly woken task is non-migratable while current is migratable
1480 * - current will be preempted on the next reschedule
1482 * we should check to see if current can readily move to a different
1483 * cpu. If so, we will reschedule to allow the push logic to try
1484 * to move current somewhere else, making room for our non-migratable
1487 if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1488 check_preempt_equal_prio(rq, p);
1492 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1493 struct rt_rq *rt_rq)
1495 struct rt_prio_array *array = &rt_rq->active;
1496 struct sched_rt_entity *next = NULL;
1497 struct list_head *queue;
1500 idx = sched_find_first_bit(array->bitmap);
1501 BUG_ON(idx >= MAX_RT_PRIO);
1503 queue = array->queue + idx;
1504 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1509 static struct task_struct *_pick_next_task_rt(struct rq *rq)
1511 struct sched_rt_entity *rt_se;
1512 struct task_struct *p;
1513 struct rt_rq *rt_rq = &rq->rt;
1516 rt_se = pick_next_rt_entity(rq, rt_rq);
1518 rt_rq = group_rt_rq(rt_se);
1521 p = rt_task_of(rt_se);
1522 p->se.exec_start = rq_clock_task(rq);
1527 static struct task_struct *
1528 pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
1530 struct task_struct *p;
1531 struct rt_rq *rt_rq = &rq->rt;
1533 if (need_pull_rt_task(rq, prev)) {
1535 * This is OK, because current is on_cpu, which avoids it being
1536 * picked for load-balance and preemption/IRQs are still
1537 * disabled avoiding further scheduler activity on it and we're
1538 * being very careful to re-start the picking loop.
1540 rq_unpin_lock(rq, rf);
1542 rq_repin_lock(rq, rf);
1544 * pull_rt_task() can drop (and re-acquire) rq->lock; this
1545 * means a dl or stop task can slip in, in which case we need
1546 * to re-start task selection.
1548 if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||
1549 rq->dl.dl_nr_running))
1554 * We may dequeue prev's rt_rq in put_prev_task().
1555 * So, we update time before rt_nr_running check.
1557 if (prev->sched_class == &rt_sched_class)
1560 if (!rt_rq->rt_queued)
1563 put_prev_task(rq, prev);
1565 p = _pick_next_task_rt(rq);
1567 /* The running task is never eligible for pushing */
1568 dequeue_pushable_task(rq, p);
1570 queue_push_tasks(rq);
1575 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1580 * The previous task needs to be made eligible for pushing
1581 * if it is still active
1583 if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
1584 enqueue_pushable_task(rq, p);
1589 /* Only try algorithms three times */
1590 #define RT_MAX_TRIES 3
1592 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1594 if (!task_running(rq, p) &&
1595 cpumask_test_cpu(cpu, &p->cpus_allowed))
1601 * Return the highest pushable rq's task, which is suitable to be executed
1602 * on the cpu, NULL otherwise
1604 static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
1606 struct plist_head *head = &rq->rt.pushable_tasks;
1607 struct task_struct *p;
1609 if (!has_pushable_tasks(rq))
1612 plist_for_each_entry(p, head, pushable_tasks) {
1613 if (pick_rt_task(rq, p, cpu))
1620 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1622 static int find_lowest_rq(struct task_struct *task)
1624 struct sched_domain *sd;
1625 struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
1626 int this_cpu = smp_processor_id();
1627 int cpu = task_cpu(task);
1629 /* Make sure the mask is initialized first */
1630 if (unlikely(!lowest_mask))
1633 if (task->nr_cpus_allowed == 1)
1634 return -1; /* No other targets possible */
1636 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1637 return -1; /* No targets found */
1640 * At this point we have built a mask of cpus representing the
1641 * lowest priority tasks in the system. Now we want to elect
1642 * the best one based on our affinity and topology.
1644 * We prioritize the last cpu that the task executed on since
1645 * it is most likely cache-hot in that location.
1647 if (cpumask_test_cpu(cpu, lowest_mask))
1651 * Otherwise, we consult the sched_domains span maps to figure
1652 * out which cpu is logically closest to our hot cache data.
1654 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1655 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1658 for_each_domain(cpu, sd) {
1659 if (sd->flags & SD_WAKE_AFFINE) {
1663 * "this_cpu" is cheaper to preempt than a
1666 if (this_cpu != -1 &&
1667 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1672 best_cpu = cpumask_first_and(lowest_mask,
1673 sched_domain_span(sd));
1674 if (best_cpu < nr_cpu_ids) {
1683 * And finally, if there were no matches within the domains
1684 * just give the caller *something* to work with from the compatible
1690 cpu = cpumask_any(lowest_mask);
1691 if (cpu < nr_cpu_ids)
1696 /* Will lock the rq it finds */
1697 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1699 struct rq *lowest_rq = NULL;
1703 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1704 cpu = find_lowest_rq(task);
1706 if ((cpu == -1) || (cpu == rq->cpu))
1709 lowest_rq = cpu_rq(cpu);
1711 if (lowest_rq->rt.highest_prio.curr <= task->prio) {
1713 * Target rq has tasks of equal or higher priority,
1714 * retrying does not release any lock and is unlikely
1715 * to yield a different result.
1721 /* if the prio of this runqueue changed, try again */
1722 if (double_lock_balance(rq, lowest_rq)) {
1724 * We had to unlock the run queue. In
1725 * the mean time, task could have
1726 * migrated already or had its affinity changed.
1727 * Also make sure that it wasn't scheduled on its rq.
1729 if (unlikely(task_rq(task) != rq ||
1730 !cpumask_test_cpu(lowest_rq->cpu, &task->cpus_allowed) ||
1731 task_running(rq, task) ||
1733 !task_on_rq_queued(task))) {
1735 double_unlock_balance(rq, lowest_rq);
1741 /* If this rq is still suitable use it. */
1742 if (lowest_rq->rt.highest_prio.curr > task->prio)
1746 double_unlock_balance(rq, lowest_rq);
1753 static struct task_struct *pick_next_pushable_task(struct rq *rq)
1755 struct task_struct *p;
1757 if (!has_pushable_tasks(rq))
1760 p = plist_first_entry(&rq->rt.pushable_tasks,
1761 struct task_struct, pushable_tasks);
1763 BUG_ON(rq->cpu != task_cpu(p));
1764 BUG_ON(task_current(rq, p));
1765 BUG_ON(p->nr_cpus_allowed <= 1);
1767 BUG_ON(!task_on_rq_queued(p));
1768 BUG_ON(!rt_task(p));
1774 * If the current CPU has more than one RT task, see if the non
1775 * running task can migrate over to a CPU that is running a task
1776 * of lesser priority.
1778 static int push_rt_task(struct rq *rq)
1780 struct task_struct *next_task;
1781 struct rq *lowest_rq;
1784 if (!rq->rt.overloaded)
1787 next_task = pick_next_pushable_task(rq);
1792 if (unlikely(next_task == rq->curr)) {
1798 * It's possible that the next_task slipped in of
1799 * higher priority than current. If that's the case
1800 * just reschedule current.
1802 if (unlikely(next_task->prio < rq->curr->prio)) {
1807 /* We might release rq lock */
1808 get_task_struct(next_task);
1810 /* find_lock_lowest_rq locks the rq if found */
1811 lowest_rq = find_lock_lowest_rq(next_task, rq);
1813 struct task_struct *task;
1815 * find_lock_lowest_rq releases rq->lock
1816 * so it is possible that next_task has migrated.
1818 * We need to make sure that the task is still on the same
1819 * run-queue and is also still the next task eligible for
1822 task = pick_next_pushable_task(rq);
1823 if (task == next_task) {
1825 * The task hasn't migrated, and is still the next
1826 * eligible task, but we failed to find a run-queue
1827 * to push it to. Do not retry in this case, since
1828 * other cpus will pull from us when ready.
1834 /* No more tasks, just exit */
1838 * Something has shifted, try again.
1840 put_task_struct(next_task);
1845 deactivate_task(rq, next_task, 0);
1846 set_task_cpu(next_task, lowest_rq->cpu);
1847 activate_task(lowest_rq, next_task, 0);
1850 resched_curr(lowest_rq);
1852 double_unlock_balance(rq, lowest_rq);
1855 put_task_struct(next_task);
1860 static void push_rt_tasks(struct rq *rq)
1862 /* push_rt_task will return true if it moved an RT */
1863 while (push_rt_task(rq))
1867 #ifdef HAVE_RT_PUSH_IPI
1870 * When a high priority task schedules out from a CPU and a lower priority
1871 * task is scheduled in, a check is made to see if there's any RT tasks
1872 * on other CPUs that are waiting to run because a higher priority RT task
1873 * is currently running on its CPU. In this case, the CPU with multiple RT
1874 * tasks queued on it (overloaded) needs to be notified that a CPU has opened
1875 * up that may be able to run one of its non-running queued RT tasks.
1877 * All CPUs with overloaded RT tasks need to be notified as there is currently
1878 * no way to know which of these CPUs have the highest priority task waiting
1879 * to run. Instead of trying to take a spinlock on each of these CPUs,
1880 * which has shown to cause large latency when done on machines with many
1881 * CPUs, sending an IPI to the CPUs to have them push off the overloaded
1882 * RT tasks waiting to run.
1884 * Just sending an IPI to each of the CPUs is also an issue, as on large
1885 * count CPU machines, this can cause an IPI storm on a CPU, especially
1886 * if its the only CPU with multiple RT tasks queued, and a large number
1887 * of CPUs scheduling a lower priority task at the same time.
1889 * Each root domain has its own irq work function that can iterate over
1890 * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT
1891 * tassk must be checked if there's one or many CPUs that are lowering
1892 * their priority, there's a single irq work iterator that will try to
1893 * push off RT tasks that are waiting to run.
1895 * When a CPU schedules a lower priority task, it will kick off the
1896 * irq work iterator that will jump to each CPU with overloaded RT tasks.
1897 * As it only takes the first CPU that schedules a lower priority task
1898 * to start the process, the rto_start variable is incremented and if
1899 * the atomic result is one, then that CPU will try to take the rto_lock.
1900 * This prevents high contention on the lock as the process handles all
1901 * CPUs scheduling lower priority tasks.
1903 * All CPUs that are scheduling a lower priority task will increment the
1904 * rt_loop_next variable. This will make sure that the irq work iterator
1905 * checks all RT overloaded CPUs whenever a CPU schedules a new lower
1906 * priority task, even if the iterator is in the middle of a scan. Incrementing
1907 * the rt_loop_next will cause the iterator to perform another scan.
1910 static int rto_next_cpu(struct rq *rq)
1912 struct root_domain *rd = rq->rd;
1917 * When starting the IPI RT pushing, the rto_cpu is set to -1,
1918 * rt_next_cpu() will simply return the first CPU found in
1921 * If rto_next_cpu() is called with rto_cpu is a valid cpu, it
1922 * will return the next CPU found in the rto_mask.
1924 * If there are no more CPUs left in the rto_mask, then a check is made
1925 * against rto_loop and rto_loop_next. rto_loop is only updated with
1926 * the rto_lock held, but any CPU may increment the rto_loop_next
1927 * without any locking.
1931 /* When rto_cpu is -1 this acts like cpumask_first() */
1932 cpu = cpumask_next(rd->rto_cpu, rd->rto_mask);
1936 if (cpu < nr_cpu_ids)
1942 * ACQUIRE ensures we see the @rto_mask changes
1943 * made prior to the @next value observed.
1945 * Matches WMB in rt_set_overload().
1947 next = atomic_read_acquire(&rd->rto_loop_next);
1949 if (rd->rto_loop == next)
1952 rd->rto_loop = next;
1958 static inline bool rto_start_trylock(atomic_t *v)
1960 return !atomic_cmpxchg_acquire(v, 0, 1);
1963 static inline void rto_start_unlock(atomic_t *v)
1965 atomic_set_release(v, 0);
1968 static void tell_cpu_to_push(struct rq *rq)
1972 /* Keep the loop going if the IPI is currently active */
1973 atomic_inc(&rq->rd->rto_loop_next);
1975 /* Only one CPU can initiate a loop at a time */
1976 if (!rto_start_trylock(&rq->rd->rto_loop_start))
1979 raw_spin_lock(&rq->rd->rto_lock);
1982 * The rto_cpu is updated under the lock, if it has a valid cpu
1983 * then the IPI is still running and will continue due to the
1984 * update to loop_next, and nothing needs to be done here.
1985 * Otherwise it is finishing up and an ipi needs to be sent.
1987 if (rq->rd->rto_cpu < 0)
1988 cpu = rto_next_cpu(rq);
1990 raw_spin_unlock(&rq->rd->rto_lock);
1992 rto_start_unlock(&rq->rd->rto_loop_start);
1995 irq_work_queue_on(&rq->rd->rto_push_work, cpu);
1998 /* Called from hardirq context */
1999 void rto_push_irq_work_func(struct irq_work *work)
2007 * We do not need to grab the lock to check for has_pushable_tasks.
2008 * When it gets updated, a check is made if a push is possible.
2010 if (has_pushable_tasks(rq)) {
2011 raw_spin_lock(&rq->lock);
2013 raw_spin_unlock(&rq->lock);
2016 raw_spin_lock(&rq->rd->rto_lock);
2018 /* Pass the IPI to the next rt overloaded queue */
2019 cpu = rto_next_cpu(rq);
2021 raw_spin_unlock(&rq->rd->rto_lock);
2026 /* Try the next RT overloaded CPU */
2027 irq_work_queue_on(&rq->rd->rto_push_work, cpu);
2029 #endif /* HAVE_RT_PUSH_IPI */
2031 static void pull_rt_task(struct rq *this_rq)
2033 int this_cpu = this_rq->cpu, cpu;
2034 bool resched = false;
2035 struct task_struct *p;
2037 int rt_overload_count = rt_overloaded(this_rq);
2039 if (likely(!rt_overload_count))
2043 * Match the barrier from rt_set_overloaded; this guarantees that if we
2044 * see overloaded we must also see the rto_mask bit.
2048 /* If we are the only overloaded CPU do nothing */
2049 if (rt_overload_count == 1 &&
2050 cpumask_test_cpu(this_rq->cpu, this_rq->rd->rto_mask))
2053 #ifdef HAVE_RT_PUSH_IPI
2054 if (sched_feat(RT_PUSH_IPI)) {
2055 tell_cpu_to_push(this_rq);
2060 for_each_cpu(cpu, this_rq->rd->rto_mask) {
2061 if (this_cpu == cpu)
2064 src_rq = cpu_rq(cpu);
2067 * Don't bother taking the src_rq->lock if the next highest
2068 * task is known to be lower-priority than our current task.
2069 * This may look racy, but if this value is about to go
2070 * logically higher, the src_rq will push this task away.
2071 * And if its going logically lower, we do not care
2073 if (src_rq->rt.highest_prio.next >=
2074 this_rq->rt.highest_prio.curr)
2078 * We can potentially drop this_rq's lock in
2079 * double_lock_balance, and another CPU could
2082 double_lock_balance(this_rq, src_rq);
2085 * We can pull only a task, which is pushable
2086 * on its rq, and no others.
2088 p = pick_highest_pushable_task(src_rq, this_cpu);
2091 * Do we have an RT task that preempts
2092 * the to-be-scheduled task?
2094 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
2095 WARN_ON(p == src_rq->curr);
2096 WARN_ON(!task_on_rq_queued(p));
2099 * There's a chance that p is higher in priority
2100 * than what's currently running on its cpu.
2101 * This is just that p is wakeing up and hasn't
2102 * had a chance to schedule. We only pull
2103 * p if it is lower in priority than the
2104 * current task on the run queue
2106 if (p->prio < src_rq->curr->prio)
2111 deactivate_task(src_rq, p, 0);
2112 set_task_cpu(p, this_cpu);
2113 activate_task(this_rq, p, 0);
2115 * We continue with the search, just in
2116 * case there's an even higher prio task
2117 * in another runqueue. (low likelihood
2122 double_unlock_balance(this_rq, src_rq);
2126 resched_curr(this_rq);
2130 * If we are not running and we are not going to reschedule soon, we should
2131 * try to push tasks away now
2133 static void task_woken_rt(struct rq *rq, struct task_struct *p)
2135 if (!task_running(rq, p) &&
2136 !test_tsk_need_resched(rq->curr) &&
2137 p->nr_cpus_allowed > 1 &&
2138 (dl_task(rq->curr) || rt_task(rq->curr)) &&
2139 (rq->curr->nr_cpus_allowed < 2 ||
2140 rq->curr->prio <= p->prio))
2144 /* Assumes rq->lock is held */
2145 static void rq_online_rt(struct rq *rq)
2147 if (rq->rt.overloaded)
2148 rt_set_overload(rq);
2150 __enable_runtime(rq);
2152 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
2155 /* Assumes rq->lock is held */
2156 static void rq_offline_rt(struct rq *rq)
2158 if (rq->rt.overloaded)
2159 rt_clear_overload(rq);
2161 __disable_runtime(rq);
2163 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
2167 * When switch from the rt queue, we bring ourselves to a position
2168 * that we might want to pull RT tasks from other runqueues.
2170 static void switched_from_rt(struct rq *rq, struct task_struct *p)
2173 * If there are other RT tasks then we will reschedule
2174 * and the scheduling of the other RT tasks will handle
2175 * the balancing. But if we are the last RT task
2176 * we may need to handle the pulling of RT tasks
2179 if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
2182 queue_pull_task(rq);
2185 void __init init_sched_rt_class(void)
2189 for_each_possible_cpu(i) {
2190 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
2191 GFP_KERNEL, cpu_to_node(i));
2194 #endif /* CONFIG_SMP */
2197 * When switching a task to RT, we may overload the runqueue
2198 * with RT tasks. In this case we try to push them off to
2201 static void switched_to_rt(struct rq *rq, struct task_struct *p)
2204 * If we are already running, then there's nothing
2205 * that needs to be done. But if we are not running
2206 * we may need to preempt the current running task.
2207 * If that current running task is also an RT task
2208 * then see if we can move to another run queue.
2210 if (task_on_rq_queued(p) && rq->curr != p) {
2212 if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
2213 queue_push_tasks(rq);
2214 #endif /* CONFIG_SMP */
2215 if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq)))
2221 * Priority of the task has changed. This may cause
2222 * us to initiate a push or pull.
2225 prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
2227 if (!task_on_rq_queued(p))
2230 if (rq->curr == p) {
2233 * If our priority decreases while running, we
2234 * may need to pull tasks to this runqueue.
2236 if (oldprio < p->prio)
2237 queue_pull_task(rq);
2240 * If there's a higher priority task waiting to run
2243 if (p->prio > rq->rt.highest_prio.curr)
2246 /* For UP simply resched on drop of prio */
2247 if (oldprio < p->prio)
2249 #endif /* CONFIG_SMP */
2252 * This task is not running, but if it is
2253 * greater than the current running task
2256 if (p->prio < rq->curr->prio)
2261 #ifdef CONFIG_POSIX_TIMERS
2262 static void watchdog(struct rq *rq, struct task_struct *p)
2264 unsigned long soft, hard;
2266 /* max may change after cur was read, this will be fixed next tick */
2267 soft = task_rlimit(p, RLIMIT_RTTIME);
2268 hard = task_rlimit_max(p, RLIMIT_RTTIME);
2270 if (soft != RLIM_INFINITY) {
2273 if (p->rt.watchdog_stamp != jiffies) {
2275 p->rt.watchdog_stamp = jiffies;
2278 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
2279 if (p->rt.timeout > next)
2280 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
2284 static inline void watchdog(struct rq *rq, struct task_struct *p) { }
2287 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
2289 struct sched_rt_entity *rt_se = &p->rt;
2296 * RR tasks need a special form of timeslice management.
2297 * FIFO tasks have no timeslices.
2299 if (p->policy != SCHED_RR)
2302 if (--p->rt.time_slice)
2305 p->rt.time_slice = sched_rr_timeslice;
2308 * Requeue to the end of queue if we (and all of our ancestors) are not
2309 * the only element on the queue
2311 for_each_sched_rt_entity(rt_se) {
2312 if (rt_se->run_list.prev != rt_se->run_list.next) {
2313 requeue_task_rt(rq, p, 0);
2320 static void set_curr_task_rt(struct rq *rq)
2322 struct task_struct *p = rq->curr;
2324 p->se.exec_start = rq_clock_task(rq);
2326 /* The running task is never eligible for pushing */
2327 dequeue_pushable_task(rq, p);
2330 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
2333 * Time slice is 0 for SCHED_FIFO tasks
2335 if (task->policy == SCHED_RR)
2336 return sched_rr_timeslice;
2341 const struct sched_class rt_sched_class = {
2342 .next = &fair_sched_class,
2343 .enqueue_task = enqueue_task_rt,
2344 .dequeue_task = dequeue_task_rt,
2345 .yield_task = yield_task_rt,
2347 .check_preempt_curr = check_preempt_curr_rt,
2349 .pick_next_task = pick_next_task_rt,
2350 .put_prev_task = put_prev_task_rt,
2353 .select_task_rq = select_task_rq_rt,
2355 .set_cpus_allowed = set_cpus_allowed_common,
2356 .rq_online = rq_online_rt,
2357 .rq_offline = rq_offline_rt,
2358 .task_woken = task_woken_rt,
2359 .switched_from = switched_from_rt,
2362 .set_curr_task = set_curr_task_rt,
2363 .task_tick = task_tick_rt,
2365 .get_rr_interval = get_rr_interval_rt,
2367 .prio_changed = prio_changed_rt,
2368 .switched_to = switched_to_rt,
2370 .update_curr = update_curr_rt,
2373 #ifdef CONFIG_RT_GROUP_SCHED
2375 * Ensure that the real time constraints are schedulable.
2377 static DEFINE_MUTEX(rt_constraints_mutex);
2379 /* Must be called with tasklist_lock held */
2380 static inline int tg_has_rt_tasks(struct task_group *tg)
2382 struct task_struct *g, *p;
2385 * Autogroups do not have RT tasks; see autogroup_create().
2387 if (task_group_is_autogroup(tg))
2390 for_each_process_thread(g, p) {
2391 if (rt_task(p) && task_group(p) == tg)
2398 struct rt_schedulable_data {
2399 struct task_group *tg;
2404 static int tg_rt_schedulable(struct task_group *tg, void *data)
2406 struct rt_schedulable_data *d = data;
2407 struct task_group *child;
2408 unsigned long total, sum = 0;
2409 u64 period, runtime;
2411 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
2412 runtime = tg->rt_bandwidth.rt_runtime;
2415 period = d->rt_period;
2416 runtime = d->rt_runtime;
2420 * Cannot have more runtime than the period.
2422 if (runtime > period && runtime != RUNTIME_INF)
2426 * Ensure we don't starve existing RT tasks.
2428 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
2431 total = to_ratio(period, runtime);
2434 * Nobody can have more than the global setting allows.
2436 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
2440 * The sum of our children's runtime should not exceed our own.
2442 list_for_each_entry_rcu(child, &tg->children, siblings) {
2443 period = ktime_to_ns(child->rt_bandwidth.rt_period);
2444 runtime = child->rt_bandwidth.rt_runtime;
2446 if (child == d->tg) {
2447 period = d->rt_period;
2448 runtime = d->rt_runtime;
2451 sum += to_ratio(period, runtime);
2460 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
2464 struct rt_schedulable_data data = {
2466 .rt_period = period,
2467 .rt_runtime = runtime,
2471 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
2477 static int tg_set_rt_bandwidth(struct task_group *tg,
2478 u64 rt_period, u64 rt_runtime)
2483 * Disallowing the root group RT runtime is BAD, it would disallow the
2484 * kernel creating (and or operating) RT threads.
2486 if (tg == &root_task_group && rt_runtime == 0)
2489 /* No period doesn't make any sense. */
2493 mutex_lock(&rt_constraints_mutex);
2494 read_lock(&tasklist_lock);
2495 err = __rt_schedulable(tg, rt_period, rt_runtime);
2499 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
2500 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
2501 tg->rt_bandwidth.rt_runtime = rt_runtime;
2503 for_each_possible_cpu(i) {
2504 struct rt_rq *rt_rq = tg->rt_rq[i];
2506 raw_spin_lock(&rt_rq->rt_runtime_lock);
2507 rt_rq->rt_runtime = rt_runtime;
2508 raw_spin_unlock(&rt_rq->rt_runtime_lock);
2510 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
2512 read_unlock(&tasklist_lock);
2513 mutex_unlock(&rt_constraints_mutex);
2518 int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
2520 u64 rt_runtime, rt_period;
2522 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
2523 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
2524 if (rt_runtime_us < 0)
2525 rt_runtime = RUNTIME_INF;
2527 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
2530 long sched_group_rt_runtime(struct task_group *tg)
2534 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
2537 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
2538 do_div(rt_runtime_us, NSEC_PER_USEC);
2539 return rt_runtime_us;
2542 int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
2544 u64 rt_runtime, rt_period;
2546 rt_period = rt_period_us * NSEC_PER_USEC;
2547 rt_runtime = tg->rt_bandwidth.rt_runtime;
2549 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
2552 long sched_group_rt_period(struct task_group *tg)
2556 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
2557 do_div(rt_period_us, NSEC_PER_USEC);
2558 return rt_period_us;
2561 static int sched_rt_global_constraints(void)
2565 mutex_lock(&rt_constraints_mutex);
2566 read_lock(&tasklist_lock);
2567 ret = __rt_schedulable(NULL, 0, 0);
2568 read_unlock(&tasklist_lock);
2569 mutex_unlock(&rt_constraints_mutex);
2574 int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
2576 /* Don't accept realtime tasks when there is no way for them to run */
2577 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
2583 #else /* !CONFIG_RT_GROUP_SCHED */
2584 static int sched_rt_global_constraints(void)
2586 unsigned long flags;
2589 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
2590 for_each_possible_cpu(i) {
2591 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
2593 raw_spin_lock(&rt_rq->rt_runtime_lock);
2594 rt_rq->rt_runtime = global_rt_runtime();
2595 raw_spin_unlock(&rt_rq->rt_runtime_lock);
2597 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
2601 #endif /* CONFIG_RT_GROUP_SCHED */
2603 static int sched_rt_global_validate(void)
2605 if (sysctl_sched_rt_period <= 0)
2608 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
2609 (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
2615 static void sched_rt_do_global(void)
2617 def_rt_bandwidth.rt_runtime = global_rt_runtime();
2618 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
2621 int sched_rt_handler(struct ctl_table *table, int write,
2622 void __user *buffer, size_t *lenp,
2625 int old_period, old_runtime;
2626 static DEFINE_MUTEX(mutex);
2630 old_period = sysctl_sched_rt_period;
2631 old_runtime = sysctl_sched_rt_runtime;
2633 ret = proc_dointvec(table, write, buffer, lenp, ppos);
2635 if (!ret && write) {
2636 ret = sched_rt_global_validate();
2640 ret = sched_dl_global_validate();
2644 ret = sched_rt_global_constraints();
2648 sched_rt_do_global();
2649 sched_dl_do_global();
2653 sysctl_sched_rt_period = old_period;
2654 sysctl_sched_rt_runtime = old_runtime;
2656 mutex_unlock(&mutex);
2661 int sched_rr_handler(struct ctl_table *table, int write,
2662 void __user *buffer, size_t *lenp,
2666 static DEFINE_MUTEX(mutex);
2669 ret = proc_dointvec(table, write, buffer, lenp, ppos);
2671 * Make sure that internally we keep jiffies.
2672 * Also, writing zero resets the timeslice to default:
2674 if (!ret && write) {
2675 sched_rr_timeslice =
2676 sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
2677 msecs_to_jiffies(sysctl_sched_rr_timeslice);
2679 mutex_unlock(&mutex);
2683 #ifdef CONFIG_SCHED_DEBUG
2684 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
2686 void print_rt_stats(struct seq_file *m, int cpu)
2689 struct rt_rq *rt_rq;
2692 for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
2693 print_rt_rq(m, cpu, rt_rq);
2696 #endif /* CONFIG_SCHED_DEBUG */