2 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
8 #include <linux/slab.h>
9 #include <linux/irq_work.h>
13 int sched_rr_timeslice = 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;
63 hrtimer_forward_now(&rt_b->rt_period_timer, rt_b->rt_period);
64 hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED);
66 raw_spin_unlock(&rt_b->rt_runtime_lock);
69 #if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI)
70 static void push_irq_work_func(struct irq_work *work);
73 void init_rt_rq(struct rt_rq *rt_rq)
75 struct rt_prio_array *array;
78 array = &rt_rq->active;
79 for (i = 0; i < MAX_RT_PRIO; i++) {
80 INIT_LIST_HEAD(array->queue + i);
81 __clear_bit(i, array->bitmap);
83 /* delimiter for bitsearch: */
84 __set_bit(MAX_RT_PRIO, array->bitmap);
86 #if defined CONFIG_SMP
87 rt_rq->highest_prio.curr = MAX_RT_PRIO;
88 rt_rq->highest_prio.next = MAX_RT_PRIO;
89 rt_rq->rt_nr_migratory = 0;
90 rt_rq->overloaded = 0;
91 plist_head_init(&rt_rq->pushable_tasks);
93 #ifdef HAVE_RT_PUSH_IPI
94 rt_rq->push_flags = 0;
95 rt_rq->push_cpu = nr_cpu_ids;
96 raw_spin_lock_init(&rt_rq->push_lock);
97 init_irq_work(&rt_rq->push_work, push_irq_work_func);
99 #endif /* CONFIG_SMP */
100 /* We start is dequeued state, because no RT tasks are queued */
101 rt_rq->rt_queued = 0;
104 rt_rq->rt_throttled = 0;
105 rt_rq->rt_runtime = 0;
106 raw_spin_lock_init(&rt_rq->rt_runtime_lock);
109 #ifdef CONFIG_RT_GROUP_SCHED
110 static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
112 hrtimer_cancel(&rt_b->rt_period_timer);
115 #define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
117 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
119 #ifdef CONFIG_SCHED_DEBUG
120 WARN_ON_ONCE(!rt_entity_is_task(rt_se));
122 return container_of(rt_se, struct task_struct, rt);
125 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
130 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
135 static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
137 struct rt_rq *rt_rq = rt_se->rt_rq;
142 void free_rt_sched_group(struct task_group *tg)
147 destroy_rt_bandwidth(&tg->rt_bandwidth);
149 for_each_possible_cpu(i) {
160 void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
161 struct sched_rt_entity *rt_se, int cpu,
162 struct sched_rt_entity *parent)
164 struct rq *rq = cpu_rq(cpu);
166 rt_rq->highest_prio.curr = MAX_RT_PRIO;
167 rt_rq->rt_nr_boosted = 0;
171 tg->rt_rq[cpu] = rt_rq;
172 tg->rt_se[cpu] = rt_se;
178 rt_se->rt_rq = &rq->rt;
180 rt_se->rt_rq = parent->my_q;
183 rt_se->parent = parent;
184 INIT_LIST_HEAD(&rt_se->run_list);
187 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
190 struct sched_rt_entity *rt_se;
193 tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
196 tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
200 init_rt_bandwidth(&tg->rt_bandwidth,
201 ktime_to_ns(def_rt_bandwidth.rt_period), 0);
203 for_each_possible_cpu(i) {
204 rt_rq = kzalloc_node(sizeof(struct rt_rq),
205 GFP_KERNEL, cpu_to_node(i));
209 rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
210 GFP_KERNEL, cpu_to_node(i));
215 rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
216 init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
227 #else /* CONFIG_RT_GROUP_SCHED */
229 #define rt_entity_is_task(rt_se) (1)
231 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
233 return container_of(rt_se, struct task_struct, rt);
236 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
238 return container_of(rt_rq, struct rq, rt);
241 static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
243 struct task_struct *p = rt_task_of(rt_se);
248 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
250 struct rq *rq = rq_of_rt_se(rt_se);
255 void free_rt_sched_group(struct task_group *tg) { }
257 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
261 #endif /* CONFIG_RT_GROUP_SCHED */
265 static void pull_rt_task(struct rq *this_rq);
267 static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
269 /* Try to pull RT tasks here if we lower this rq's prio */
270 return rq->rt.highest_prio.curr > prev->prio;
273 static inline int rt_overloaded(struct rq *rq)
275 return atomic_read(&rq->rd->rto_count);
278 static inline void rt_set_overload(struct rq *rq)
283 cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
285 * Make sure the mask is visible before we set
286 * the overload count. That is checked to determine
287 * if we should look at the mask. It would be a shame
288 * if we looked at the mask, but the mask was not
291 * Matched by the barrier in pull_rt_task().
294 atomic_inc(&rq->rd->rto_count);
297 static inline void rt_clear_overload(struct rq *rq)
302 /* the order here really doesn't matter */
303 atomic_dec(&rq->rd->rto_count);
304 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
307 static void update_rt_migration(struct rt_rq *rt_rq)
309 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
310 if (!rt_rq->overloaded) {
311 rt_set_overload(rq_of_rt_rq(rt_rq));
312 rt_rq->overloaded = 1;
314 } else if (rt_rq->overloaded) {
315 rt_clear_overload(rq_of_rt_rq(rt_rq));
316 rt_rq->overloaded = 0;
320 static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
322 struct task_struct *p;
324 if (!rt_entity_is_task(rt_se))
327 p = rt_task_of(rt_se);
328 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
330 rt_rq->rt_nr_total++;
331 if (p->nr_cpus_allowed > 1)
332 rt_rq->rt_nr_migratory++;
334 update_rt_migration(rt_rq);
337 static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
339 struct task_struct *p;
341 if (!rt_entity_is_task(rt_se))
344 p = rt_task_of(rt_se);
345 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
347 rt_rq->rt_nr_total--;
348 if (p->nr_cpus_allowed > 1)
349 rt_rq->rt_nr_migratory--;
351 update_rt_migration(rt_rq);
354 static inline int has_pushable_tasks(struct rq *rq)
356 return !plist_head_empty(&rq->rt.pushable_tasks);
359 static DEFINE_PER_CPU(struct callback_head, rt_push_head);
360 static DEFINE_PER_CPU(struct callback_head, rt_pull_head);
362 static void push_rt_tasks(struct rq *);
363 static void pull_rt_task(struct rq *);
365 static inline void queue_push_tasks(struct rq *rq)
367 if (!has_pushable_tasks(rq))
370 queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
373 static inline void queue_pull_task(struct rq *rq)
375 queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
378 static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
380 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
381 plist_node_init(&p->pushable_tasks, p->prio);
382 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
384 /* Update the highest prio pushable task */
385 if (p->prio < rq->rt.highest_prio.next)
386 rq->rt.highest_prio.next = p->prio;
389 static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
391 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
393 /* Update the new highest prio pushable task */
394 if (has_pushable_tasks(rq)) {
395 p = plist_first_entry(&rq->rt.pushable_tasks,
396 struct task_struct, pushable_tasks);
397 rq->rt.highest_prio.next = p->prio;
399 rq->rt.highest_prio.next = MAX_RT_PRIO;
404 static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
408 static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
413 void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
418 void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
422 static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
427 static inline void pull_rt_task(struct rq *this_rq)
431 static inline void queue_push_tasks(struct rq *rq)
434 #endif /* CONFIG_SMP */
436 static void enqueue_top_rt_rq(struct rt_rq *rt_rq);
437 static void dequeue_top_rt_rq(struct rt_rq *rt_rq);
439 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
441 return !list_empty(&rt_se->run_list);
444 #ifdef CONFIG_RT_GROUP_SCHED
446 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
451 return rt_rq->rt_runtime;
454 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
456 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
459 typedef struct task_group *rt_rq_iter_t;
461 static inline struct task_group *next_task_group(struct task_group *tg)
464 tg = list_entry_rcu(tg->list.next,
465 typeof(struct task_group), list);
466 } while (&tg->list != &task_groups && task_group_is_autogroup(tg));
468 if (&tg->list == &task_groups)
474 #define for_each_rt_rq(rt_rq, iter, rq) \
475 for (iter = container_of(&task_groups, typeof(*iter), list); \
476 (iter = next_task_group(iter)) && \
477 (rt_rq = iter->rt_rq[cpu_of(rq)]);)
479 #define for_each_sched_rt_entity(rt_se) \
480 for (; rt_se; rt_se = rt_se->parent)
482 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
487 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
488 static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
490 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
492 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
493 struct rq *rq = rq_of_rt_rq(rt_rq);
494 struct sched_rt_entity *rt_se;
496 int cpu = cpu_of(rq);
498 rt_se = rt_rq->tg->rt_se[cpu];
500 if (rt_rq->rt_nr_running) {
502 enqueue_top_rt_rq(rt_rq);
503 else if (!on_rt_rq(rt_se))
504 enqueue_rt_entity(rt_se, false);
506 if (rt_rq->highest_prio.curr < curr->prio)
511 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
513 struct sched_rt_entity *rt_se;
514 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
516 rt_se = rt_rq->tg->rt_se[cpu];
519 dequeue_top_rt_rq(rt_rq);
520 else if (on_rt_rq(rt_se))
521 dequeue_rt_entity(rt_se);
524 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
526 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
529 static int rt_se_boosted(struct sched_rt_entity *rt_se)
531 struct rt_rq *rt_rq = group_rt_rq(rt_se);
532 struct task_struct *p;
535 return !!rt_rq->rt_nr_boosted;
537 p = rt_task_of(rt_se);
538 return p->prio != p->normal_prio;
542 static inline const struct cpumask *sched_rt_period_mask(void)
544 return this_rq()->rd->span;
547 static inline const struct cpumask *sched_rt_period_mask(void)
549 return cpu_online_mask;
554 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
556 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
559 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
561 return &rt_rq->tg->rt_bandwidth;
564 #else /* !CONFIG_RT_GROUP_SCHED */
566 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
568 return rt_rq->rt_runtime;
571 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
573 return ktime_to_ns(def_rt_bandwidth.rt_period);
576 typedef struct rt_rq *rt_rq_iter_t;
578 #define for_each_rt_rq(rt_rq, iter, rq) \
579 for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
581 #define for_each_sched_rt_entity(rt_se) \
582 for (; rt_se; rt_se = NULL)
584 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
589 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
591 struct rq *rq = rq_of_rt_rq(rt_rq);
593 if (!rt_rq->rt_nr_running)
596 enqueue_top_rt_rq(rt_rq);
600 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
602 dequeue_top_rt_rq(rt_rq);
605 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
607 return rt_rq->rt_throttled;
610 static inline const struct cpumask *sched_rt_period_mask(void)
612 return cpu_online_mask;
616 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
618 return &cpu_rq(cpu)->rt;
621 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
623 return &def_rt_bandwidth;
626 #endif /* CONFIG_RT_GROUP_SCHED */
628 bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
630 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
632 return (hrtimer_active(&rt_b->rt_period_timer) ||
633 rt_rq->rt_time < rt_b->rt_runtime);
638 * We ran out of runtime, see if we can borrow some from our neighbours.
640 static void do_balance_runtime(struct rt_rq *rt_rq)
642 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
643 struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;
647 weight = cpumask_weight(rd->span);
649 raw_spin_lock(&rt_b->rt_runtime_lock);
650 rt_period = ktime_to_ns(rt_b->rt_period);
651 for_each_cpu(i, rd->span) {
652 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
658 raw_spin_lock(&iter->rt_runtime_lock);
660 * Either all rqs have inf runtime and there's nothing to steal
661 * or __disable_runtime() below sets a specific rq to inf to
662 * indicate its been disabled and disalow stealing.
664 if (iter->rt_runtime == RUNTIME_INF)
668 * From runqueues with spare time, take 1/n part of their
669 * spare time, but no more than our period.
671 diff = iter->rt_runtime - iter->rt_time;
673 diff = div_u64((u64)diff, weight);
674 if (rt_rq->rt_runtime + diff > rt_period)
675 diff = rt_period - rt_rq->rt_runtime;
676 iter->rt_runtime -= diff;
677 rt_rq->rt_runtime += diff;
678 if (rt_rq->rt_runtime == rt_period) {
679 raw_spin_unlock(&iter->rt_runtime_lock);
684 raw_spin_unlock(&iter->rt_runtime_lock);
686 raw_spin_unlock(&rt_b->rt_runtime_lock);
690 * Ensure this RQ takes back all the runtime it lend to its neighbours.
692 static void __disable_runtime(struct rq *rq)
694 struct root_domain *rd = rq->rd;
698 if (unlikely(!scheduler_running))
701 for_each_rt_rq(rt_rq, iter, rq) {
702 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
706 raw_spin_lock(&rt_b->rt_runtime_lock);
707 raw_spin_lock(&rt_rq->rt_runtime_lock);
709 * Either we're all inf and nobody needs to borrow, or we're
710 * already disabled and thus have nothing to do, or we have
711 * exactly the right amount of runtime to take out.
713 if (rt_rq->rt_runtime == RUNTIME_INF ||
714 rt_rq->rt_runtime == rt_b->rt_runtime)
716 raw_spin_unlock(&rt_rq->rt_runtime_lock);
719 * Calculate the difference between what we started out with
720 * and what we current have, that's the amount of runtime
721 * we lend and now have to reclaim.
723 want = rt_b->rt_runtime - rt_rq->rt_runtime;
726 * Greedy reclaim, take back as much as we can.
728 for_each_cpu(i, rd->span) {
729 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
733 * Can't reclaim from ourselves or disabled runqueues.
735 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
738 raw_spin_lock(&iter->rt_runtime_lock);
740 diff = min_t(s64, iter->rt_runtime, want);
741 iter->rt_runtime -= diff;
744 iter->rt_runtime -= want;
747 raw_spin_unlock(&iter->rt_runtime_lock);
753 raw_spin_lock(&rt_rq->rt_runtime_lock);
755 * We cannot be left wanting - that would mean some runtime
756 * leaked out of the system.
761 * Disable all the borrow logic by pretending we have inf
762 * runtime - in which case borrowing doesn't make sense.
764 rt_rq->rt_runtime = RUNTIME_INF;
765 rt_rq->rt_throttled = 0;
766 raw_spin_unlock(&rt_rq->rt_runtime_lock);
767 raw_spin_unlock(&rt_b->rt_runtime_lock);
769 /* Make rt_rq available for pick_next_task() */
770 sched_rt_rq_enqueue(rt_rq);
774 static void __enable_runtime(struct rq *rq)
779 if (unlikely(!scheduler_running))
783 * Reset each runqueue's bandwidth settings
785 for_each_rt_rq(rt_rq, iter, rq) {
786 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
788 raw_spin_lock(&rt_b->rt_runtime_lock);
789 raw_spin_lock(&rt_rq->rt_runtime_lock);
790 rt_rq->rt_runtime = rt_b->rt_runtime;
792 rt_rq->rt_throttled = 0;
793 raw_spin_unlock(&rt_rq->rt_runtime_lock);
794 raw_spin_unlock(&rt_b->rt_runtime_lock);
798 static void balance_runtime(struct rt_rq *rt_rq)
800 if (!sched_feat(RT_RUNTIME_SHARE))
803 if (rt_rq->rt_time > rt_rq->rt_runtime) {
804 raw_spin_unlock(&rt_rq->rt_runtime_lock);
805 do_balance_runtime(rt_rq);
806 raw_spin_lock(&rt_rq->rt_runtime_lock);
809 #else /* !CONFIG_SMP */
810 static inline void balance_runtime(struct rt_rq *rt_rq) {}
811 #endif /* CONFIG_SMP */
813 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
815 int i, idle = 1, throttled = 0;
816 const struct cpumask *span;
818 span = sched_rt_period_mask();
819 #ifdef CONFIG_RT_GROUP_SCHED
821 * FIXME: isolated CPUs should really leave the root task group,
822 * whether they are isolcpus or were isolated via cpusets, lest
823 * the timer run on a CPU which does not service all runqueues,
824 * potentially leaving other CPUs indefinitely throttled. If
825 * isolation is really required, the user will turn the throttle
826 * off to kill the perturbations it causes anyway. Meanwhile,
827 * this maintains functionality for boot and/or troubleshooting.
829 if (rt_b == &root_task_group.rt_bandwidth)
830 span = cpu_online_mask;
832 for_each_cpu(i, span) {
834 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
835 struct rq *rq = rq_of_rt_rq(rt_rq);
837 raw_spin_lock(&rq->lock);
838 if (rt_rq->rt_time) {
841 raw_spin_lock(&rt_rq->rt_runtime_lock);
842 if (rt_rq->rt_throttled)
843 balance_runtime(rt_rq);
844 runtime = rt_rq->rt_runtime;
845 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
846 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
847 rt_rq->rt_throttled = 0;
851 * When we're idle and a woken (rt) task is
852 * throttled check_preempt_curr() will set
853 * skip_update and the time between the wakeup
854 * and this unthrottle will get accounted as
857 if (rt_rq->rt_nr_running && rq->curr == rq->idle)
858 rq_clock_skip_update(rq, false);
860 if (rt_rq->rt_time || rt_rq->rt_nr_running)
862 raw_spin_unlock(&rt_rq->rt_runtime_lock);
863 } else if (rt_rq->rt_nr_running) {
865 if (!rt_rq_throttled(rt_rq))
868 if (rt_rq->rt_throttled)
872 sched_rt_rq_enqueue(rt_rq);
873 raw_spin_unlock(&rq->lock);
876 if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
882 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
884 #ifdef CONFIG_RT_GROUP_SCHED
885 struct rt_rq *rt_rq = group_rt_rq(rt_se);
888 return rt_rq->highest_prio.curr;
891 return rt_task_of(rt_se)->prio;
894 static void dump_throttled_rt_tasks(struct rt_rq *rt_rq)
896 struct rt_prio_array *array = &rt_rq->active;
897 struct sched_rt_entity *rt_se;
900 char *end = buf + sizeof(buf);
903 pos += snprintf(pos, sizeof(buf),
904 "sched: RT throttling activated for rt_rq %p (cpu %d)\n",
905 rt_rq, cpu_of(rq_of_rt_rq(rt_rq)));
907 if (bitmap_empty(array->bitmap, MAX_RT_PRIO))
910 pos += snprintf(pos, end - pos, "potential CPU hogs:\n");
911 idx = sched_find_first_bit(array->bitmap);
912 while (idx < MAX_RT_PRIO) {
913 list_for_each_entry(rt_se, array->queue + idx, run_list) {
914 struct task_struct *p;
916 if (!rt_entity_is_task(rt_se))
919 p = rt_task_of(rt_se);
921 pos += snprintf(pos, end - pos, "\t%s (%d)\n",
924 idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx + 1);
927 printk_deferred("%s", buf);
930 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
932 u64 runtime = sched_rt_runtime(rt_rq);
934 if (rt_rq->rt_throttled)
935 return rt_rq_throttled(rt_rq);
937 if (runtime >= sched_rt_period(rt_rq))
940 balance_runtime(rt_rq);
941 runtime = sched_rt_runtime(rt_rq);
942 if (runtime == RUNTIME_INF)
945 if (rt_rq->rt_time > runtime) {
946 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
949 * Don't actually throttle groups that have no runtime assigned
950 * but accrue some time due to boosting.
952 if (likely(rt_b->rt_runtime)) {
953 static bool once = false;
955 rt_rq->rt_throttled = 1;
959 dump_throttled_rt_tasks(rt_rq);
963 * In case we did anyway, make it go away,
964 * replenishment is a joke, since it will replenish us
970 if (rt_rq_throttled(rt_rq)) {
971 sched_rt_rq_dequeue(rt_rq);
980 * Update the current task's runtime statistics. Skip current tasks that
981 * are not in our scheduling class.
983 static void update_curr_rt(struct rq *rq)
985 struct task_struct *curr = rq->curr;
986 struct sched_rt_entity *rt_se = &curr->rt;
989 if (curr->sched_class != &rt_sched_class)
992 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
993 if (unlikely((s64)delta_exec <= 0))
996 schedstat_set(curr->se.statistics.exec_max,
997 max(curr->se.statistics.exec_max, delta_exec));
999 curr->se.sum_exec_runtime += delta_exec;
1000 account_group_exec_runtime(curr, delta_exec);
1002 curr->se.exec_start = rq_clock_task(rq);
1003 cpuacct_charge(curr, delta_exec);
1005 sched_rt_avg_update(rq, delta_exec);
1007 if (!rt_bandwidth_enabled())
1010 for_each_sched_rt_entity(rt_se) {
1011 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1013 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
1014 raw_spin_lock(&rt_rq->rt_runtime_lock);
1015 rt_rq->rt_time += delta_exec;
1016 if (sched_rt_runtime_exceeded(rt_rq))
1018 raw_spin_unlock(&rt_rq->rt_runtime_lock);
1024 dequeue_top_rt_rq(struct rt_rq *rt_rq)
1026 struct rq *rq = rq_of_rt_rq(rt_rq);
1028 BUG_ON(&rq->rt != rt_rq);
1030 if (!rt_rq->rt_queued)
1033 BUG_ON(!rq->nr_running);
1035 sub_nr_running(rq, rt_rq->rt_nr_running);
1036 rt_rq->rt_queued = 0;
1040 enqueue_top_rt_rq(struct rt_rq *rt_rq)
1042 struct rq *rq = rq_of_rt_rq(rt_rq);
1044 BUG_ON(&rq->rt != rt_rq);
1046 if (rt_rq->rt_queued)
1048 if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running)
1051 add_nr_running(rq, rt_rq->rt_nr_running);
1052 rt_rq->rt_queued = 1;
1055 #if defined CONFIG_SMP
1058 inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1060 struct rq *rq = rq_of_rt_rq(rt_rq);
1062 #ifdef CONFIG_RT_GROUP_SCHED
1064 * Change rq's cpupri only if rt_rq is the top queue.
1066 if (&rq->rt != rt_rq)
1069 if (rq->online && prio < prev_prio)
1070 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
1074 dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1076 struct rq *rq = rq_of_rt_rq(rt_rq);
1078 #ifdef CONFIG_RT_GROUP_SCHED
1080 * Change rq's cpupri only if rt_rq is the top queue.
1082 if (&rq->rt != rt_rq)
1085 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
1086 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
1089 #else /* CONFIG_SMP */
1092 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1094 void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1096 #endif /* CONFIG_SMP */
1098 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
1100 inc_rt_prio(struct rt_rq *rt_rq, int prio)
1102 int prev_prio = rt_rq->highest_prio.curr;
1104 if (prio < prev_prio)
1105 rt_rq->highest_prio.curr = prio;
1107 inc_rt_prio_smp(rt_rq, prio, prev_prio);
1111 dec_rt_prio(struct rt_rq *rt_rq, int prio)
1113 int prev_prio = rt_rq->highest_prio.curr;
1115 if (rt_rq->rt_nr_running) {
1117 WARN_ON(prio < prev_prio);
1120 * This may have been our highest task, and therefore
1121 * we may have some recomputation to do
1123 if (prio == prev_prio) {
1124 struct rt_prio_array *array = &rt_rq->active;
1126 rt_rq->highest_prio.curr =
1127 sched_find_first_bit(array->bitmap);
1131 rt_rq->highest_prio.curr = MAX_RT_PRIO;
1133 dec_rt_prio_smp(rt_rq, prio, prev_prio);
1138 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
1139 static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
1141 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
1143 #ifdef CONFIG_RT_GROUP_SCHED
1146 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1148 if (rt_se_boosted(rt_se))
1149 rt_rq->rt_nr_boosted++;
1152 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
1156 dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1158 if (rt_se_boosted(rt_se))
1159 rt_rq->rt_nr_boosted--;
1161 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
1164 #else /* CONFIG_RT_GROUP_SCHED */
1167 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1169 start_rt_bandwidth(&def_rt_bandwidth);
1173 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1175 #endif /* CONFIG_RT_GROUP_SCHED */
1178 unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
1180 struct rt_rq *group_rq = group_rt_rq(rt_se);
1183 return group_rq->rt_nr_running;
1189 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1191 int prio = rt_se_prio(rt_se);
1193 WARN_ON(!rt_prio(prio));
1194 rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
1196 inc_rt_prio(rt_rq, prio);
1197 inc_rt_migration(rt_se, rt_rq);
1198 inc_rt_group(rt_se, rt_rq);
1202 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1204 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
1205 WARN_ON(!rt_rq->rt_nr_running);
1206 rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
1208 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
1209 dec_rt_migration(rt_se, rt_rq);
1210 dec_rt_group(rt_se, rt_rq);
1213 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1215 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1216 struct rt_prio_array *array = &rt_rq->active;
1217 struct rt_rq *group_rq = group_rt_rq(rt_se);
1218 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1221 * Don't enqueue the group if its throttled, or when empty.
1222 * The latter is a consequence of the former when a child group
1223 * get throttled and the current group doesn't have any other
1226 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
1230 list_add(&rt_se->run_list, queue);
1232 list_add_tail(&rt_se->run_list, queue);
1233 __set_bit(rt_se_prio(rt_se), array->bitmap);
1235 inc_rt_tasks(rt_se, rt_rq);
1238 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
1240 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1241 struct rt_prio_array *array = &rt_rq->active;
1243 list_del_init(&rt_se->run_list);
1244 if (list_empty(array->queue + rt_se_prio(rt_se)))
1245 __clear_bit(rt_se_prio(rt_se), array->bitmap);
1247 dec_rt_tasks(rt_se, rt_rq);
1251 * Because the prio of an upper entry depends on the lower
1252 * entries, we must remove entries top - down.
1254 static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
1256 struct sched_rt_entity *back = NULL;
1258 for_each_sched_rt_entity(rt_se) {
1263 dequeue_top_rt_rq(rt_rq_of_se(back));
1265 for (rt_se = back; rt_se; rt_se = rt_se->back) {
1266 if (on_rt_rq(rt_se))
1267 __dequeue_rt_entity(rt_se);
1271 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1273 struct rq *rq = rq_of_rt_se(rt_se);
1275 dequeue_rt_stack(rt_se);
1276 for_each_sched_rt_entity(rt_se)
1277 __enqueue_rt_entity(rt_se, head);
1278 enqueue_top_rt_rq(&rq->rt);
1281 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
1283 struct rq *rq = rq_of_rt_se(rt_se);
1285 dequeue_rt_stack(rt_se);
1287 for_each_sched_rt_entity(rt_se) {
1288 struct rt_rq *rt_rq = group_rt_rq(rt_se);
1290 if (rt_rq && rt_rq->rt_nr_running)
1291 __enqueue_rt_entity(rt_se, false);
1293 enqueue_top_rt_rq(&rq->rt);
1297 * Adding/removing a task to/from a priority array:
1300 enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1302 struct sched_rt_entity *rt_se = &p->rt;
1304 if (flags & ENQUEUE_WAKEUP)
1307 enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
1308 walt_inc_cumulative_runnable_avg(rq, p);
1310 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1311 enqueue_pushable_task(rq, p);
1314 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1316 struct sched_rt_entity *rt_se = &p->rt;
1319 dequeue_rt_entity(rt_se);
1320 walt_dec_cumulative_runnable_avg(rq, p);
1322 dequeue_pushable_task(rq, p);
1326 * Put task to the head or the end of the run list without the overhead of
1327 * dequeue followed by enqueue.
1330 requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
1332 if (on_rt_rq(rt_se)) {
1333 struct rt_prio_array *array = &rt_rq->active;
1334 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1337 list_move(&rt_se->run_list, queue);
1339 list_move_tail(&rt_se->run_list, queue);
1343 static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
1345 struct sched_rt_entity *rt_se = &p->rt;
1346 struct rt_rq *rt_rq;
1348 for_each_sched_rt_entity(rt_se) {
1349 rt_rq = rt_rq_of_se(rt_se);
1350 requeue_rt_entity(rt_rq, rt_se, head);
1354 static void yield_task_rt(struct rq *rq)
1356 requeue_task_rt(rq, rq->curr, 0);
1360 static int find_lowest_rq(struct task_struct *task);
1363 select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
1365 struct task_struct *curr;
1368 /* For anything but wake ups, just return the task_cpu */
1369 if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
1375 curr = READ_ONCE(rq->curr); /* unlocked access */
1378 * If the current task on @p's runqueue is an RT task, then
1379 * try to see if we can wake this RT task up on another
1380 * runqueue. Otherwise simply start this RT task
1381 * on its current runqueue.
1383 * We want to avoid overloading runqueues. If the woken
1384 * task is a higher priority, then it will stay on this CPU
1385 * and the lower prio task should be moved to another CPU.
1386 * Even though this will probably make the lower prio task
1387 * lose its cache, we do not want to bounce a higher task
1388 * around just because it gave up its CPU, perhaps for a
1391 * For equal prio tasks, we just let the scheduler sort it out.
1393 * Otherwise, just let it ride on the affined RQ and the
1394 * post-schedule router will push the preempted task away
1396 * This test is optimistic, if we get it wrong the load-balancer
1397 * will have to sort it out.
1399 if (curr && unlikely(rt_task(curr)) &&
1400 (curr->nr_cpus_allowed < 2 ||
1401 curr->prio <= p->prio)) {
1402 int target = find_lowest_rq(p);
1405 * Don't bother moving it if the destination CPU is
1406 * not running a lower priority task.
1409 p->prio < cpu_rq(target)->rt.highest_prio.curr)
1418 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1421 * Current can't be migrated, useless to reschedule,
1422 * let's hope p can move out.
1424 if (rq->curr->nr_cpus_allowed == 1 ||
1425 !cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1429 * p is migratable, so let's not schedule it and
1430 * see if it is pushed or pulled somewhere else.
1432 if (p->nr_cpus_allowed != 1
1433 && cpupri_find(&rq->rd->cpupri, p, NULL))
1437 * There appears to be other cpus that can accept
1438 * current and none to run 'p', so lets reschedule
1439 * to try and push current away:
1441 requeue_task_rt(rq, p, 1);
1445 #endif /* CONFIG_SMP */
1448 * Preempt the current task with a newly woken task if needed:
1450 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1452 if (p->prio < rq->curr->prio) {
1461 * - the newly woken task is of equal priority to the current task
1462 * - the newly woken task is non-migratable while current is migratable
1463 * - current will be preempted on the next reschedule
1465 * we should check to see if current can readily move to a different
1466 * cpu. If so, we will reschedule to allow the push logic to try
1467 * to move current somewhere else, making room for our non-migratable
1470 if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1471 check_preempt_equal_prio(rq, p);
1476 static void sched_rt_update_capacity_req(struct rq *rq)
1478 u64 total, used, age_stamp, avg;
1484 sched_avg_update(rq);
1486 * Since we're reading these variables without serialization make sure
1487 * we read them once before doing sanity checks on them.
1489 age_stamp = READ_ONCE(rq->age_stamp);
1490 avg = READ_ONCE(rq->rt_avg);
1491 delta = rq_clock(rq) - age_stamp;
1493 if (unlikely(delta < 0))
1496 total = sched_avg_period() + delta;
1498 used = div_u64(avg, total);
1499 if (unlikely(used > SCHED_CAPACITY_SCALE))
1500 used = SCHED_CAPACITY_SCALE;
1502 set_rt_cpu_capacity(rq->cpu, 1, (unsigned long)(used));
1505 static inline void sched_rt_update_capacity_req(struct rq *rq)
1510 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1511 struct rt_rq *rt_rq)
1513 struct rt_prio_array *array = &rt_rq->active;
1514 struct sched_rt_entity *next = NULL;
1515 struct list_head *queue;
1518 idx = sched_find_first_bit(array->bitmap);
1519 BUG_ON(idx >= MAX_RT_PRIO);
1521 queue = array->queue + idx;
1522 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1527 static struct task_struct *_pick_next_task_rt(struct rq *rq)
1529 struct sched_rt_entity *rt_se;
1530 struct task_struct *p;
1531 struct rt_rq *rt_rq = &rq->rt;
1534 rt_se = pick_next_rt_entity(rq, rt_rq);
1536 rt_rq = group_rt_rq(rt_se);
1539 p = rt_task_of(rt_se);
1540 p->se.exec_start = rq_clock_task(rq);
1545 static struct task_struct *
1546 pick_next_task_rt(struct rq *rq, struct task_struct *prev)
1548 struct task_struct *p;
1549 struct rt_rq *rt_rq = &rq->rt;
1551 if (need_pull_rt_task(rq, prev)) {
1553 * This is OK, because current is on_cpu, which avoids it being
1554 * picked for load-balance and preemption/IRQs are still
1555 * disabled avoiding further scheduler activity on it and we're
1556 * being very careful to re-start the picking loop.
1558 lockdep_unpin_lock(&rq->lock);
1560 lockdep_pin_lock(&rq->lock);
1562 * pull_rt_task() can drop (and re-acquire) rq->lock; this
1563 * means a dl or stop task can slip in, in which case we need
1564 * to re-start task selection.
1566 if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||
1567 rq->dl.dl_nr_running))
1572 * We may dequeue prev's rt_rq in put_prev_task().
1573 * So, we update time before rt_nr_running check.
1575 if (prev->sched_class == &rt_sched_class)
1578 if (!rt_rq->rt_queued) {
1580 * The next task to be picked on this rq will have a lower
1581 * priority than rt tasks so we can spend some time to update
1582 * the capacity used by rt tasks based on the last activity.
1583 * This value will be the used as an estimation of the next
1586 sched_rt_update_capacity_req(rq);
1590 put_prev_task(rq, prev);
1592 p = _pick_next_task_rt(rq);
1594 /* The running task is never eligible for pushing */
1595 dequeue_pushable_task(rq, p);
1597 queue_push_tasks(rq);
1602 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1607 * The previous task needs to be made eligible for pushing
1608 * if it is still active
1610 if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
1611 enqueue_pushable_task(rq, p);
1616 /* Only try algorithms three times */
1617 #define RT_MAX_TRIES 3
1619 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1621 if (!task_running(rq, p) &&
1622 cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
1628 * Return the highest pushable rq's task, which is suitable to be executed
1629 * on the cpu, NULL otherwise
1631 static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
1633 struct plist_head *head = &rq->rt.pushable_tasks;
1634 struct task_struct *p;
1636 if (!has_pushable_tasks(rq))
1639 plist_for_each_entry(p, head, pushable_tasks) {
1640 if (pick_rt_task(rq, p, cpu))
1647 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1649 static int find_lowest_rq(struct task_struct *task)
1651 struct sched_domain *sd;
1652 struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
1653 int this_cpu = smp_processor_id();
1654 int cpu = task_cpu(task);
1656 /* Make sure the mask is initialized first */
1657 if (unlikely(!lowest_mask))
1660 if (task->nr_cpus_allowed == 1)
1661 return -1; /* No other targets possible */
1663 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1664 return -1; /* No targets found */
1667 * At this point we have built a mask of cpus representing the
1668 * lowest priority tasks in the system. Now we want to elect
1669 * the best one based on our affinity and topology.
1671 * We prioritize the last cpu that the task executed on since
1672 * it is most likely cache-hot in that location.
1674 if (cpumask_test_cpu(cpu, lowest_mask))
1678 * Otherwise, we consult the sched_domains span maps to figure
1679 * out which cpu is logically closest to our hot cache data.
1681 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1682 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1685 for_each_domain(cpu, sd) {
1686 if (sd->flags & SD_WAKE_AFFINE) {
1690 * "this_cpu" is cheaper to preempt than a
1693 if (this_cpu != -1 &&
1694 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1699 best_cpu = cpumask_first_and(lowest_mask,
1700 sched_domain_span(sd));
1701 if (best_cpu < nr_cpu_ids) {
1710 * And finally, if there were no matches within the domains
1711 * just give the caller *something* to work with from the compatible
1717 cpu = cpumask_any(lowest_mask);
1718 if (cpu < nr_cpu_ids)
1723 /* Will lock the rq it finds */
1724 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1726 struct rq *lowest_rq = NULL;
1730 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1731 cpu = find_lowest_rq(task);
1733 if ((cpu == -1) || (cpu == rq->cpu))
1736 lowest_rq = cpu_rq(cpu);
1738 if (lowest_rq->rt.highest_prio.curr <= task->prio) {
1740 * Target rq has tasks of equal or higher priority,
1741 * retrying does not release any lock and is unlikely
1742 * to yield a different result.
1748 /* if the prio of this runqueue changed, try again */
1749 if (double_lock_balance(rq, lowest_rq)) {
1751 * We had to unlock the run queue. In
1752 * the mean time, task could have
1753 * migrated already or had its affinity changed.
1754 * Also make sure that it wasn't scheduled on its rq.
1756 if (unlikely(task_rq(task) != rq ||
1757 !cpumask_test_cpu(lowest_rq->cpu,
1758 tsk_cpus_allowed(task)) ||
1759 task_running(rq, task) ||
1760 !task_on_rq_queued(task))) {
1762 double_unlock_balance(rq, lowest_rq);
1768 /* If this rq is still suitable use it. */
1769 if (lowest_rq->rt.highest_prio.curr > task->prio)
1773 double_unlock_balance(rq, lowest_rq);
1780 static struct task_struct *pick_next_pushable_task(struct rq *rq)
1782 struct task_struct *p;
1784 if (!has_pushable_tasks(rq))
1787 p = plist_first_entry(&rq->rt.pushable_tasks,
1788 struct task_struct, pushable_tasks);
1790 BUG_ON(rq->cpu != task_cpu(p));
1791 BUG_ON(task_current(rq, p));
1792 BUG_ON(p->nr_cpus_allowed <= 1);
1794 BUG_ON(!task_on_rq_queued(p));
1795 BUG_ON(!rt_task(p));
1801 * If the current CPU has more than one RT task, see if the non
1802 * running task can migrate over to a CPU that is running a task
1803 * of lesser priority.
1805 static int push_rt_task(struct rq *rq)
1807 struct task_struct *next_task;
1808 struct rq *lowest_rq;
1811 if (!rq->rt.overloaded)
1814 next_task = pick_next_pushable_task(rq);
1819 if (unlikely(next_task == rq->curr)) {
1825 * It's possible that the next_task slipped in of
1826 * higher priority than current. If that's the case
1827 * just reschedule current.
1829 if (unlikely(next_task->prio < rq->curr->prio)) {
1834 /* We might release rq lock */
1835 get_task_struct(next_task);
1837 /* find_lock_lowest_rq locks the rq if found */
1838 lowest_rq = find_lock_lowest_rq(next_task, rq);
1840 struct task_struct *task;
1842 * find_lock_lowest_rq releases rq->lock
1843 * so it is possible that next_task has migrated.
1845 * We need to make sure that the task is still on the same
1846 * run-queue and is also still the next task eligible for
1849 task = pick_next_pushable_task(rq);
1850 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1852 * The task hasn't migrated, and is still the next
1853 * eligible task, but we failed to find a run-queue
1854 * to push it to. Do not retry in this case, since
1855 * other cpus will pull from us when ready.
1861 /* No more tasks, just exit */
1865 * Something has shifted, try again.
1867 put_task_struct(next_task);
1872 deactivate_task(rq, next_task, 0);
1873 set_task_cpu(next_task, lowest_rq->cpu);
1874 activate_task(lowest_rq, next_task, 0);
1877 resched_curr(lowest_rq);
1879 double_unlock_balance(rq, lowest_rq);
1882 put_task_struct(next_task);
1887 static void push_rt_tasks(struct rq *rq)
1889 /* push_rt_task will return true if it moved an RT */
1890 while (push_rt_task(rq))
1894 #ifdef HAVE_RT_PUSH_IPI
1896 * The search for the next cpu always starts at rq->cpu and ends
1897 * when we reach rq->cpu again. It will never return rq->cpu.
1898 * This returns the next cpu to check, or nr_cpu_ids if the loop
1901 * rq->rt.push_cpu holds the last cpu returned by this function,
1902 * or if this is the first instance, it must hold rq->cpu.
1904 static int rto_next_cpu(struct rq *rq)
1906 int prev_cpu = rq->rt.push_cpu;
1909 cpu = cpumask_next(prev_cpu, rq->rd->rto_mask);
1912 * If the previous cpu is less than the rq's CPU, then it already
1913 * passed the end of the mask, and has started from the beginning.
1914 * We end if the next CPU is greater or equal to rq's CPU.
1916 if (prev_cpu < rq->cpu) {
1920 } else if (cpu >= nr_cpu_ids) {
1922 * We passed the end of the mask, start at the beginning.
1923 * If the result is greater or equal to the rq's CPU, then
1924 * the loop is finished.
1926 cpu = cpumask_first(rq->rd->rto_mask);
1930 rq->rt.push_cpu = cpu;
1932 /* Return cpu to let the caller know if the loop is finished or not */
1936 static int find_next_push_cpu(struct rq *rq)
1942 cpu = rto_next_cpu(rq);
1943 if (cpu >= nr_cpu_ids)
1945 next_rq = cpu_rq(cpu);
1947 /* Make sure the next rq can push to this rq */
1948 if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr)
1955 #define RT_PUSH_IPI_EXECUTING 1
1956 #define RT_PUSH_IPI_RESTART 2
1958 static void tell_cpu_to_push(struct rq *rq)
1962 if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
1963 raw_spin_lock(&rq->rt.push_lock);
1964 /* Make sure it's still executing */
1965 if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
1967 * Tell the IPI to restart the loop as things have
1968 * changed since it started.
1970 rq->rt.push_flags |= RT_PUSH_IPI_RESTART;
1971 raw_spin_unlock(&rq->rt.push_lock);
1974 raw_spin_unlock(&rq->rt.push_lock);
1977 /* When here, there's no IPI going around */
1979 rq->rt.push_cpu = rq->cpu;
1980 cpu = find_next_push_cpu(rq);
1981 if (cpu >= nr_cpu_ids)
1984 rq->rt.push_flags = RT_PUSH_IPI_EXECUTING;
1986 irq_work_queue_on(&rq->rt.push_work, cpu);
1989 /* Called from hardirq context */
1990 static void try_to_push_tasks(void *arg)
1992 struct rt_rq *rt_rq = arg;
1993 struct rq *rq, *src_rq;
1997 this_cpu = rt_rq->push_cpu;
1999 /* Paranoid check */
2000 BUG_ON(this_cpu != smp_processor_id());
2002 rq = cpu_rq(this_cpu);
2003 src_rq = rq_of_rt_rq(rt_rq);
2006 if (has_pushable_tasks(rq)) {
2007 raw_spin_lock(&rq->lock);
2009 raw_spin_unlock(&rq->lock);
2012 /* Pass the IPI to the next rt overloaded queue */
2013 raw_spin_lock(&rt_rq->push_lock);
2015 * If the source queue changed since the IPI went out,
2016 * we need to restart the search from that CPU again.
2018 if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) {
2019 rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART;
2020 rt_rq->push_cpu = src_rq->cpu;
2023 cpu = find_next_push_cpu(src_rq);
2025 if (cpu >= nr_cpu_ids)
2026 rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING;
2027 raw_spin_unlock(&rt_rq->push_lock);
2029 if (cpu >= nr_cpu_ids)
2033 * It is possible that a restart caused this CPU to be
2034 * chosen again. Don't bother with an IPI, just see if we
2035 * have more to push.
2037 if (unlikely(cpu == rq->cpu))
2040 /* Try the next RT overloaded CPU */
2041 irq_work_queue_on(&rt_rq->push_work, cpu);
2044 static void push_irq_work_func(struct irq_work *work)
2046 struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work);
2048 try_to_push_tasks(rt_rq);
2050 #endif /* HAVE_RT_PUSH_IPI */
2052 static void pull_rt_task(struct rq *this_rq)
2054 int this_cpu = this_rq->cpu, cpu;
2055 bool resched = false;
2056 struct task_struct *p;
2059 if (likely(!rt_overloaded(this_rq)))
2063 * Match the barrier from rt_set_overloaded; this guarantees that if we
2064 * see overloaded we must also see the rto_mask bit.
2068 #ifdef HAVE_RT_PUSH_IPI
2069 if (sched_feat(RT_PUSH_IPI)) {
2070 tell_cpu_to_push(this_rq);
2075 for_each_cpu(cpu, this_rq->rd->rto_mask) {
2076 if (this_cpu == cpu)
2079 src_rq = cpu_rq(cpu);
2082 * Don't bother taking the src_rq->lock if the next highest
2083 * task is known to be lower-priority than our current task.
2084 * This may look racy, but if this value is about to go
2085 * logically higher, the src_rq will push this task away.
2086 * And if its going logically lower, we do not care
2088 if (src_rq->rt.highest_prio.next >=
2089 this_rq->rt.highest_prio.curr)
2093 * We can potentially drop this_rq's lock in
2094 * double_lock_balance, and another CPU could
2097 double_lock_balance(this_rq, src_rq);
2100 * We can pull only a task, which is pushable
2101 * on its rq, and no others.
2103 p = pick_highest_pushable_task(src_rq, this_cpu);
2106 * Do we have an RT task that preempts
2107 * the to-be-scheduled task?
2109 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
2110 WARN_ON(p == src_rq->curr);
2111 WARN_ON(!task_on_rq_queued(p));
2114 * There's a chance that p is higher in priority
2115 * than what's currently running on its cpu.
2116 * This is just that p is wakeing up and hasn't
2117 * had a chance to schedule. We only pull
2118 * p if it is lower in priority than the
2119 * current task on the run queue
2121 if (p->prio < src_rq->curr->prio)
2126 deactivate_task(src_rq, p, 0);
2127 set_task_cpu(p, this_cpu);
2128 activate_task(this_rq, p, 0);
2130 * We continue with the search, just in
2131 * case there's an even higher prio task
2132 * in another runqueue. (low likelihood
2137 double_unlock_balance(this_rq, src_rq);
2141 resched_curr(this_rq);
2145 * If we are not running and we are not going to reschedule soon, we should
2146 * try to push tasks away now
2148 static void task_woken_rt(struct rq *rq, struct task_struct *p)
2150 if (!task_running(rq, p) &&
2151 !test_tsk_need_resched(rq->curr) &&
2152 p->nr_cpus_allowed > 1 &&
2153 (dl_task(rq->curr) || rt_task(rq->curr)) &&
2154 (rq->curr->nr_cpus_allowed < 2 ||
2155 rq->curr->prio <= p->prio))
2159 /* Assumes rq->lock is held */
2160 static void rq_online_rt(struct rq *rq)
2162 if (rq->rt.overloaded)
2163 rt_set_overload(rq);
2165 __enable_runtime(rq);
2167 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
2170 /* Assumes rq->lock is held */
2171 static void rq_offline_rt(struct rq *rq)
2173 if (rq->rt.overloaded)
2174 rt_clear_overload(rq);
2176 __disable_runtime(rq);
2178 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
2182 * When switch from the rt queue, we bring ourselves to a position
2183 * that we might want to pull RT tasks from other runqueues.
2185 static void switched_from_rt(struct rq *rq, struct task_struct *p)
2188 * If there are other RT tasks then we will reschedule
2189 * and the scheduling of the other RT tasks will handle
2190 * the balancing. But if we are the last RT task
2191 * we may need to handle the pulling of RT tasks
2194 if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
2197 queue_pull_task(rq);
2200 void __init init_sched_rt_class(void)
2204 for_each_possible_cpu(i) {
2205 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
2206 GFP_KERNEL, cpu_to_node(i));
2209 #endif /* CONFIG_SMP */
2212 * When switching a task to RT, we may overload the runqueue
2213 * with RT tasks. In this case we try to push them off to
2216 static void switched_to_rt(struct rq *rq, struct task_struct *p)
2219 * If we are already running, then there's nothing
2220 * that needs to be done. But if we are not running
2221 * we may need to preempt the current running task.
2222 * If that current running task is also an RT task
2223 * then see if we can move to another run queue.
2225 if (task_on_rq_queued(p) && rq->curr != p) {
2227 if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
2228 queue_push_tasks(rq);
2230 if (p->prio < rq->curr->prio)
2232 #endif /* CONFIG_SMP */
2237 * Priority of the task has changed. This may cause
2238 * us to initiate a push or pull.
2241 prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
2243 if (!task_on_rq_queued(p))
2246 if (rq->curr == p) {
2249 * If our priority decreases while running, we
2250 * may need to pull tasks to this runqueue.
2252 if (oldprio < p->prio)
2253 queue_pull_task(rq);
2256 * If there's a higher priority task waiting to run
2259 if (p->prio > rq->rt.highest_prio.curr)
2262 /* For UP simply resched on drop of prio */
2263 if (oldprio < p->prio)
2265 #endif /* CONFIG_SMP */
2268 * This task is not running, but if it is
2269 * greater than the current running task
2272 if (p->prio < rq->curr->prio)
2277 static void watchdog(struct rq *rq, struct task_struct *p)
2279 unsigned long soft, hard;
2281 /* max may change after cur was read, this will be fixed next tick */
2282 soft = task_rlimit(p, RLIMIT_RTTIME);
2283 hard = task_rlimit_max(p, RLIMIT_RTTIME);
2285 if (soft != RLIM_INFINITY) {
2288 if (p->rt.watchdog_stamp != jiffies) {
2290 p->rt.watchdog_stamp = jiffies;
2293 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
2294 if (p->rt.timeout > next)
2295 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
2299 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
2301 struct sched_rt_entity *rt_se = &p->rt;
2305 if (rq->rt.rt_nr_running)
2306 sched_rt_update_capacity_req(rq);
2311 * RR tasks need a special form of timeslice management.
2312 * FIFO tasks have no timeslices.
2314 if (p->policy != SCHED_RR)
2317 if (--p->rt.time_slice)
2320 p->rt.time_slice = sched_rr_timeslice;
2323 * Requeue to the end of queue if we (and all of our ancestors) are not
2324 * the only element on the queue
2326 for_each_sched_rt_entity(rt_se) {
2327 if (rt_se->run_list.prev != rt_se->run_list.next) {
2328 requeue_task_rt(rq, p, 0);
2335 static void set_curr_task_rt(struct rq *rq)
2337 struct task_struct *p = rq->curr;
2339 p->se.exec_start = rq_clock_task(rq);
2341 /* The running task is never eligible for pushing */
2342 dequeue_pushable_task(rq, p);
2345 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
2348 * Time slice is 0 for SCHED_FIFO tasks
2350 if (task->policy == SCHED_RR)
2351 return sched_rr_timeslice;
2356 const struct sched_class rt_sched_class = {
2357 .next = &fair_sched_class,
2358 .enqueue_task = enqueue_task_rt,
2359 .dequeue_task = dequeue_task_rt,
2360 .yield_task = yield_task_rt,
2362 .check_preempt_curr = check_preempt_curr_rt,
2364 .pick_next_task = pick_next_task_rt,
2365 .put_prev_task = put_prev_task_rt,
2368 .select_task_rq = select_task_rq_rt,
2370 .set_cpus_allowed = set_cpus_allowed_common,
2371 .rq_online = rq_online_rt,
2372 .rq_offline = rq_offline_rt,
2373 .task_woken = task_woken_rt,
2374 .switched_from = switched_from_rt,
2377 .set_curr_task = set_curr_task_rt,
2378 .task_tick = task_tick_rt,
2380 .get_rr_interval = get_rr_interval_rt,
2382 .prio_changed = prio_changed_rt,
2383 .switched_to = switched_to_rt,
2385 .update_curr = update_curr_rt,
2388 #ifdef CONFIG_SCHED_DEBUG
2389 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
2391 void print_rt_stats(struct seq_file *m, int cpu)
2394 struct rt_rq *rt_rq;
2397 for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
2398 print_rt_rq(m, cpu, rt_rq);
2401 #endif /* CONFIG_SCHED_DEBUG */