2 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
8 #include <linux/slab.h>
9 #include <linux/irq_work.h>
11 int sched_rr_timeslice = RR_TIMESLICE;
13 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
15 struct rt_bandwidth def_rt_bandwidth;
17 static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
19 struct rt_bandwidth *rt_b =
20 container_of(timer, struct rt_bandwidth, rt_period_timer);
24 raw_spin_lock(&rt_b->rt_runtime_lock);
26 overrun = hrtimer_forward_now(timer, rt_b->rt_period);
30 raw_spin_unlock(&rt_b->rt_runtime_lock);
31 idle = do_sched_rt_period_timer(rt_b, overrun);
32 raw_spin_lock(&rt_b->rt_runtime_lock);
35 rt_b->rt_period_active = 0;
36 raw_spin_unlock(&rt_b->rt_runtime_lock);
38 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
41 void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
43 rt_b->rt_period = ns_to_ktime(period);
44 rt_b->rt_runtime = runtime;
46 raw_spin_lock_init(&rt_b->rt_runtime_lock);
48 hrtimer_init(&rt_b->rt_period_timer,
49 CLOCK_MONOTONIC, HRTIMER_MODE_REL);
50 rt_b->rt_period_timer.irqsafe = 1;
51 rt_b->rt_period_timer.function = sched_rt_period_timer;
54 static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
56 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
59 raw_spin_lock(&rt_b->rt_runtime_lock);
60 if (!rt_b->rt_period_active) {
61 rt_b->rt_period_active = 1;
62 hrtimer_forward_now(&rt_b->rt_period_timer, rt_b->rt_period);
63 hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED);
65 raw_spin_unlock(&rt_b->rt_runtime_lock);
68 #if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI)
69 static void push_irq_work_func(struct irq_work *work);
72 void init_rt_rq(struct rt_rq *rt_rq)
74 struct rt_prio_array *array;
77 array = &rt_rq->active;
78 for (i = 0; i < MAX_RT_PRIO; i++) {
79 INIT_LIST_HEAD(array->queue + i);
80 __clear_bit(i, array->bitmap);
82 /* delimiter for bitsearch: */
83 __set_bit(MAX_RT_PRIO, array->bitmap);
85 #if defined CONFIG_SMP
86 rt_rq->highest_prio.curr = MAX_RT_PRIO;
87 rt_rq->highest_prio.next = MAX_RT_PRIO;
88 rt_rq->rt_nr_migratory = 0;
89 rt_rq->overloaded = 0;
90 plist_head_init(&rt_rq->pushable_tasks);
92 #ifdef HAVE_RT_PUSH_IPI
93 rt_rq->push_flags = 0;
94 rt_rq->push_cpu = nr_cpu_ids;
95 raw_spin_lock_init(&rt_rq->push_lock);
96 init_irq_work(&rt_rq->push_work, push_irq_work_func);
97 rt_rq->push_work.flags |= IRQ_WORK_HARD_IRQ;
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 (tsk_nr_cpus_allowed(p) > 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 (tsk_nr_cpus_allowed(p) > 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 int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
896 u64 runtime = sched_rt_runtime(rt_rq);
898 if (rt_rq->rt_throttled)
899 return rt_rq_throttled(rt_rq);
901 if (runtime >= sched_rt_period(rt_rq))
904 balance_runtime(rt_rq);
905 runtime = sched_rt_runtime(rt_rq);
906 if (runtime == RUNTIME_INF)
909 if (rt_rq->rt_time > runtime) {
910 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
913 * Don't actually throttle groups that have no runtime assigned
914 * but accrue some time due to boosting.
916 if (likely(rt_b->rt_runtime)) {
917 rt_rq->rt_throttled = 1;
918 printk_deferred_once("sched: RT throttling activated\n");
921 * In case we did anyway, make it go away,
922 * replenishment is a joke, since it will replenish us
928 if (rt_rq_throttled(rt_rq)) {
929 sched_rt_rq_dequeue(rt_rq);
938 * Update the current task's runtime statistics. Skip current tasks that
939 * are not in our scheduling class.
941 static void update_curr_rt(struct rq *rq)
943 struct task_struct *curr = rq->curr;
944 struct sched_rt_entity *rt_se = &curr->rt;
947 if (curr->sched_class != &rt_sched_class)
950 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
951 if (unlikely((s64)delta_exec <= 0))
954 schedstat_set(curr->se.statistics.exec_max,
955 max(curr->se.statistics.exec_max, delta_exec));
957 curr->se.sum_exec_runtime += delta_exec;
958 account_group_exec_runtime(curr, delta_exec);
960 curr->se.exec_start = rq_clock_task(rq);
961 cpuacct_charge(curr, delta_exec);
963 sched_rt_avg_update(rq, delta_exec);
965 if (!rt_bandwidth_enabled())
968 for_each_sched_rt_entity(rt_se) {
969 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
971 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
972 raw_spin_lock(&rt_rq->rt_runtime_lock);
973 rt_rq->rt_time += delta_exec;
974 if (sched_rt_runtime_exceeded(rt_rq))
976 raw_spin_unlock(&rt_rq->rt_runtime_lock);
982 dequeue_top_rt_rq(struct rt_rq *rt_rq)
984 struct rq *rq = rq_of_rt_rq(rt_rq);
986 BUG_ON(&rq->rt != rt_rq);
988 if (!rt_rq->rt_queued)
991 BUG_ON(!rq->nr_running);
993 sub_nr_running(rq, rt_rq->rt_nr_running);
994 rt_rq->rt_queued = 0;
998 enqueue_top_rt_rq(struct rt_rq *rt_rq)
1000 struct rq *rq = rq_of_rt_rq(rt_rq);
1002 BUG_ON(&rq->rt != rt_rq);
1004 if (rt_rq->rt_queued)
1006 if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running)
1009 add_nr_running(rq, rt_rq->rt_nr_running);
1010 rt_rq->rt_queued = 1;
1013 #if defined CONFIG_SMP
1016 inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1018 struct rq *rq = rq_of_rt_rq(rt_rq);
1020 #ifdef CONFIG_RT_GROUP_SCHED
1022 * Change rq's cpupri only if rt_rq is the top queue.
1024 if (&rq->rt != rt_rq)
1027 if (rq->online && prio < prev_prio)
1028 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
1032 dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1034 struct rq *rq = rq_of_rt_rq(rt_rq);
1036 #ifdef CONFIG_RT_GROUP_SCHED
1038 * Change rq's cpupri only if rt_rq is the top queue.
1040 if (&rq->rt != rt_rq)
1043 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
1044 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
1047 #else /* CONFIG_SMP */
1050 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1052 void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1054 #endif /* CONFIG_SMP */
1056 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
1058 inc_rt_prio(struct rt_rq *rt_rq, int prio)
1060 int prev_prio = rt_rq->highest_prio.curr;
1062 if (prio < prev_prio)
1063 rt_rq->highest_prio.curr = prio;
1065 inc_rt_prio_smp(rt_rq, prio, prev_prio);
1069 dec_rt_prio(struct rt_rq *rt_rq, int prio)
1071 int prev_prio = rt_rq->highest_prio.curr;
1073 if (rt_rq->rt_nr_running) {
1075 WARN_ON(prio < prev_prio);
1078 * This may have been our highest task, and therefore
1079 * we may have some recomputation to do
1081 if (prio == prev_prio) {
1082 struct rt_prio_array *array = &rt_rq->active;
1084 rt_rq->highest_prio.curr =
1085 sched_find_first_bit(array->bitmap);
1089 rt_rq->highest_prio.curr = MAX_RT_PRIO;
1091 dec_rt_prio_smp(rt_rq, prio, prev_prio);
1096 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
1097 static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
1099 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
1101 #ifdef CONFIG_RT_GROUP_SCHED
1104 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1106 if (rt_se_boosted(rt_se))
1107 rt_rq->rt_nr_boosted++;
1110 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
1114 dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1116 if (rt_se_boosted(rt_se))
1117 rt_rq->rt_nr_boosted--;
1119 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
1122 #else /* CONFIG_RT_GROUP_SCHED */
1125 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1127 start_rt_bandwidth(&def_rt_bandwidth);
1131 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1133 #endif /* CONFIG_RT_GROUP_SCHED */
1136 unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
1138 struct rt_rq *group_rq = group_rt_rq(rt_se);
1141 return group_rq->rt_nr_running;
1147 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1149 int prio = rt_se_prio(rt_se);
1151 WARN_ON(!rt_prio(prio));
1152 rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
1154 inc_rt_prio(rt_rq, prio);
1155 inc_rt_migration(rt_se, rt_rq);
1156 inc_rt_group(rt_se, rt_rq);
1160 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1162 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
1163 WARN_ON(!rt_rq->rt_nr_running);
1164 rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
1166 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
1167 dec_rt_migration(rt_se, rt_rq);
1168 dec_rt_group(rt_se, rt_rq);
1171 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1173 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1174 struct rt_prio_array *array = &rt_rq->active;
1175 struct rt_rq *group_rq = group_rt_rq(rt_se);
1176 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1179 * Don't enqueue the group if its throttled, or when empty.
1180 * The latter is a consequence of the former when a child group
1181 * get throttled and the current group doesn't have any other
1184 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
1188 list_add(&rt_se->run_list, queue);
1190 list_add_tail(&rt_se->run_list, queue);
1191 __set_bit(rt_se_prio(rt_se), array->bitmap);
1193 inc_rt_tasks(rt_se, rt_rq);
1196 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
1198 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1199 struct rt_prio_array *array = &rt_rq->active;
1201 list_del_init(&rt_se->run_list);
1202 if (list_empty(array->queue + rt_se_prio(rt_se)))
1203 __clear_bit(rt_se_prio(rt_se), array->bitmap);
1205 dec_rt_tasks(rt_se, rt_rq);
1209 * Because the prio of an upper entry depends on the lower
1210 * entries, we must remove entries top - down.
1212 static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
1214 struct sched_rt_entity *back = NULL;
1216 for_each_sched_rt_entity(rt_se) {
1221 dequeue_top_rt_rq(rt_rq_of_se(back));
1223 for (rt_se = back; rt_se; rt_se = rt_se->back) {
1224 if (on_rt_rq(rt_se))
1225 __dequeue_rt_entity(rt_se);
1229 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1231 struct rq *rq = rq_of_rt_se(rt_se);
1233 dequeue_rt_stack(rt_se);
1234 for_each_sched_rt_entity(rt_se)
1235 __enqueue_rt_entity(rt_se, head);
1236 enqueue_top_rt_rq(&rq->rt);
1239 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
1241 struct rq *rq = rq_of_rt_se(rt_se);
1243 dequeue_rt_stack(rt_se);
1245 for_each_sched_rt_entity(rt_se) {
1246 struct rt_rq *rt_rq = group_rt_rq(rt_se);
1248 if (rt_rq && rt_rq->rt_nr_running)
1249 __enqueue_rt_entity(rt_se, false);
1251 enqueue_top_rt_rq(&rq->rt);
1255 * Adding/removing a task to/from a priority array:
1258 enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1260 struct sched_rt_entity *rt_se = &p->rt;
1262 if (flags & ENQUEUE_WAKEUP)
1265 enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
1267 if (!task_current(rq, p) && tsk_nr_cpus_allowed(p) > 1)
1268 enqueue_pushable_task(rq, p);
1271 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1273 struct sched_rt_entity *rt_se = &p->rt;
1276 dequeue_rt_entity(rt_se);
1278 dequeue_pushable_task(rq, p);
1282 * Put task to the head or the end of the run list without the overhead of
1283 * dequeue followed by enqueue.
1286 requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
1288 if (on_rt_rq(rt_se)) {
1289 struct rt_prio_array *array = &rt_rq->active;
1290 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1293 list_move(&rt_se->run_list, queue);
1295 list_move_tail(&rt_se->run_list, queue);
1299 static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
1301 struct sched_rt_entity *rt_se = &p->rt;
1302 struct rt_rq *rt_rq;
1304 for_each_sched_rt_entity(rt_se) {
1305 rt_rq = rt_rq_of_se(rt_se);
1306 requeue_rt_entity(rt_rq, rt_se, head);
1310 static void yield_task_rt(struct rq *rq)
1312 requeue_task_rt(rq, rq->curr, 0);
1316 static int find_lowest_rq(struct task_struct *task);
1319 select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
1321 struct task_struct *curr;
1324 /* For anything but wake ups, just return the task_cpu */
1325 if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
1331 curr = READ_ONCE(rq->curr); /* unlocked access */
1334 * If the current task on @p's runqueue is an RT task, then
1335 * try to see if we can wake this RT task up on another
1336 * runqueue. Otherwise simply start this RT task
1337 * on its current runqueue.
1339 * We want to avoid overloading runqueues. If the woken
1340 * task is a higher priority, then it will stay on this CPU
1341 * and the lower prio task should be moved to another CPU.
1342 * Even though this will probably make the lower prio task
1343 * lose its cache, we do not want to bounce a higher task
1344 * around just because it gave up its CPU, perhaps for a
1347 * For equal prio tasks, we just let the scheduler sort it out.
1349 * Otherwise, just let it ride on the affined RQ and the
1350 * post-schedule router will push the preempted task away
1352 * This test is optimistic, if we get it wrong the load-balancer
1353 * will have to sort it out.
1355 if (curr && unlikely(rt_task(curr)) &&
1356 (tsk_nr_cpus_allowed(curr) < 2 ||
1357 curr->prio <= p->prio)) {
1358 int target = find_lowest_rq(p);
1361 * Don't bother moving it if the destination CPU is
1362 * not running a lower priority task.
1365 p->prio < cpu_rq(target)->rt.highest_prio.curr)
1374 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1377 * Current can't be migrated, useless to reschedule,
1378 * let's hope p can move out.
1380 if (tsk_nr_cpus_allowed(rq->curr) == 1 ||
1381 !cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1385 * p is migratable, so let's not schedule it and
1386 * see if it is pushed or pulled somewhere else.
1388 if (tsk_nr_cpus_allowed(p) != 1
1389 && cpupri_find(&rq->rd->cpupri, p, NULL))
1393 * There appears to be other cpus that can accept
1394 * current and none to run 'p', so lets reschedule
1395 * to try and push current away:
1397 requeue_task_rt(rq, p, 1);
1401 #endif /* CONFIG_SMP */
1404 * Preempt the current task with a newly woken task if needed:
1406 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1408 if (p->prio < rq->curr->prio) {
1417 * - the newly woken task is of equal priority to the current task
1418 * - the newly woken task is non-migratable while current is migratable
1419 * - current will be preempted on the next reschedule
1421 * we should check to see if current can readily move to a different
1422 * cpu. If so, we will reschedule to allow the push logic to try
1423 * to move current somewhere else, making room for our non-migratable
1426 if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1427 check_preempt_equal_prio(rq, p);
1431 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1432 struct rt_rq *rt_rq)
1434 struct rt_prio_array *array = &rt_rq->active;
1435 struct sched_rt_entity *next = NULL;
1436 struct list_head *queue;
1439 idx = sched_find_first_bit(array->bitmap);
1440 BUG_ON(idx >= MAX_RT_PRIO);
1442 queue = array->queue + idx;
1443 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1448 static struct task_struct *_pick_next_task_rt(struct rq *rq)
1450 struct sched_rt_entity *rt_se;
1451 struct task_struct *p;
1452 struct rt_rq *rt_rq = &rq->rt;
1455 rt_se = pick_next_rt_entity(rq, rt_rq);
1457 rt_rq = group_rt_rq(rt_se);
1460 p = rt_task_of(rt_se);
1461 p->se.exec_start = rq_clock_task(rq);
1466 static struct task_struct *
1467 pick_next_task_rt(struct rq *rq, struct task_struct *prev)
1469 struct task_struct *p;
1470 struct rt_rq *rt_rq = &rq->rt;
1472 if (need_pull_rt_task(rq, prev)) {
1474 * This is OK, because current is on_cpu, which avoids it being
1475 * picked for load-balance and preemption/IRQs are still
1476 * disabled avoiding further scheduler activity on it and we're
1477 * being very careful to re-start the picking loop.
1479 lockdep_unpin_lock(&rq->lock);
1481 lockdep_pin_lock(&rq->lock);
1483 * pull_rt_task() can drop (and re-acquire) rq->lock; this
1484 * means a dl or stop task can slip in, in which case we need
1485 * to re-start task selection.
1487 if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||
1488 rq->dl.dl_nr_running))
1493 * We may dequeue prev's rt_rq in put_prev_task().
1494 * So, we update time before rt_nr_running check.
1496 if (prev->sched_class == &rt_sched_class)
1499 if (!rt_rq->rt_queued)
1502 put_prev_task(rq, prev);
1504 p = _pick_next_task_rt(rq);
1506 /* The running task is never eligible for pushing */
1507 dequeue_pushable_task(rq, p);
1509 queue_push_tasks(rq);
1514 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1519 * The previous task needs to be made eligible for pushing
1520 * if it is still active
1522 if (on_rt_rq(&p->rt) && tsk_nr_cpus_allowed(p) > 1)
1523 enqueue_pushable_task(rq, p);
1528 /* Only try algorithms three times */
1529 #define RT_MAX_TRIES 3
1531 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1533 if (!task_running(rq, p) &&
1534 cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
1540 * Return the highest pushable rq's task, which is suitable to be executed
1541 * on the cpu, NULL otherwise
1543 static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
1545 struct plist_head *head = &rq->rt.pushable_tasks;
1546 struct task_struct *p;
1548 if (!has_pushable_tasks(rq))
1551 plist_for_each_entry(p, head, pushable_tasks) {
1552 if (pick_rt_task(rq, p, cpu))
1559 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1561 static int find_lowest_rq(struct task_struct *task)
1563 struct sched_domain *sd;
1564 struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
1565 int this_cpu = smp_processor_id();
1566 int cpu = task_cpu(task);
1568 /* Make sure the mask is initialized first */
1569 if (unlikely(!lowest_mask))
1572 if (tsk_nr_cpus_allowed(task) == 1)
1573 return -1; /* No other targets possible */
1575 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1576 return -1; /* No targets found */
1579 * At this point we have built a mask of cpus representing the
1580 * lowest priority tasks in the system. Now we want to elect
1581 * the best one based on our affinity and topology.
1583 * We prioritize the last cpu that the task executed on since
1584 * it is most likely cache-hot in that location.
1586 if (cpumask_test_cpu(cpu, lowest_mask))
1590 * Otherwise, we consult the sched_domains span maps to figure
1591 * out which cpu is logically closest to our hot cache data.
1593 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1594 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1597 for_each_domain(cpu, sd) {
1598 if (sd->flags & SD_WAKE_AFFINE) {
1602 * "this_cpu" is cheaper to preempt than a
1605 if (this_cpu != -1 &&
1606 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1611 best_cpu = cpumask_first_and(lowest_mask,
1612 sched_domain_span(sd));
1613 if (best_cpu < nr_cpu_ids) {
1622 * And finally, if there were no matches within the domains
1623 * just give the caller *something* to work with from the compatible
1629 cpu = cpumask_any(lowest_mask);
1630 if (cpu < nr_cpu_ids)
1635 /* Will lock the rq it finds */
1636 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1638 struct rq *lowest_rq = NULL;
1642 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1643 cpu = find_lowest_rq(task);
1645 if ((cpu == -1) || (cpu == rq->cpu))
1648 lowest_rq = cpu_rq(cpu);
1650 if (lowest_rq->rt.highest_prio.curr <= task->prio) {
1652 * Target rq has tasks of equal or higher priority,
1653 * retrying does not release any lock and is unlikely
1654 * to yield a different result.
1660 /* if the prio of this runqueue changed, try again */
1661 if (double_lock_balance(rq, lowest_rq)) {
1663 * We had to unlock the run queue. In
1664 * the mean time, task could have
1665 * migrated already or had its affinity changed.
1666 * Also make sure that it wasn't scheduled on its rq.
1668 if (unlikely(task_rq(task) != rq ||
1669 !cpumask_test_cpu(lowest_rq->cpu,
1670 tsk_cpus_allowed(task)) ||
1671 task_running(rq, task) ||
1672 !task_on_rq_queued(task))) {
1674 double_unlock_balance(rq, lowest_rq);
1680 /* If this rq is still suitable use it. */
1681 if (lowest_rq->rt.highest_prio.curr > task->prio)
1685 double_unlock_balance(rq, lowest_rq);
1692 static struct task_struct *pick_next_pushable_task(struct rq *rq)
1694 struct task_struct *p;
1696 if (!has_pushable_tasks(rq))
1699 p = plist_first_entry(&rq->rt.pushable_tasks,
1700 struct task_struct, pushable_tasks);
1702 BUG_ON(rq->cpu != task_cpu(p));
1703 BUG_ON(task_current(rq, p));
1704 BUG_ON(tsk_nr_cpus_allowed(p) <= 1);
1706 BUG_ON(!task_on_rq_queued(p));
1707 BUG_ON(!rt_task(p));
1713 * If the current CPU has more than one RT task, see if the non
1714 * running task can migrate over to a CPU that is running a task
1715 * of lesser priority.
1717 static int push_rt_task(struct rq *rq)
1719 struct task_struct *next_task;
1720 struct rq *lowest_rq;
1723 if (!rq->rt.overloaded)
1726 next_task = pick_next_pushable_task(rq);
1731 if (unlikely(next_task == rq->curr)) {
1737 * It's possible that the next_task slipped in of
1738 * higher priority than current. If that's the case
1739 * just reschedule current.
1741 if (unlikely(next_task->prio < rq->curr->prio)) {
1746 /* We might release rq lock */
1747 get_task_struct(next_task);
1749 /* find_lock_lowest_rq locks the rq if found */
1750 lowest_rq = find_lock_lowest_rq(next_task, rq);
1752 struct task_struct *task;
1754 * find_lock_lowest_rq releases rq->lock
1755 * so it is possible that next_task has migrated.
1757 * We need to make sure that the task is still on the same
1758 * run-queue and is also still the next task eligible for
1761 task = pick_next_pushable_task(rq);
1762 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1764 * The task hasn't migrated, and is still the next
1765 * eligible task, but we failed to find a run-queue
1766 * to push it to. Do not retry in this case, since
1767 * other cpus will pull from us when ready.
1773 /* No more tasks, just exit */
1777 * Something has shifted, try again.
1779 put_task_struct(next_task);
1784 deactivate_task(rq, next_task, 0);
1785 set_task_cpu(next_task, lowest_rq->cpu);
1786 activate_task(lowest_rq, next_task, 0);
1789 resched_curr(lowest_rq);
1791 double_unlock_balance(rq, lowest_rq);
1794 put_task_struct(next_task);
1799 static void push_rt_tasks(struct rq *rq)
1801 /* push_rt_task will return true if it moved an RT */
1802 while (push_rt_task(rq))
1806 #ifdef HAVE_RT_PUSH_IPI
1808 * The search for the next cpu always starts at rq->cpu and ends
1809 * when we reach rq->cpu again. It will never return rq->cpu.
1810 * This returns the next cpu to check, or nr_cpu_ids if the loop
1813 * rq->rt.push_cpu holds the last cpu returned by this function,
1814 * or if this is the first instance, it must hold rq->cpu.
1816 static int rto_next_cpu(struct rq *rq)
1818 int prev_cpu = rq->rt.push_cpu;
1821 cpu = cpumask_next(prev_cpu, rq->rd->rto_mask);
1824 * If the previous cpu is less than the rq's CPU, then it already
1825 * passed the end of the mask, and has started from the beginning.
1826 * We end if the next CPU is greater or equal to rq's CPU.
1828 if (prev_cpu < rq->cpu) {
1832 } else if (cpu >= nr_cpu_ids) {
1834 * We passed the end of the mask, start at the beginning.
1835 * If the result is greater or equal to the rq's CPU, then
1836 * the loop is finished.
1838 cpu = cpumask_first(rq->rd->rto_mask);
1842 rq->rt.push_cpu = cpu;
1844 /* Return cpu to let the caller know if the loop is finished or not */
1848 static int find_next_push_cpu(struct rq *rq)
1854 cpu = rto_next_cpu(rq);
1855 if (cpu >= nr_cpu_ids)
1857 next_rq = cpu_rq(cpu);
1859 /* Make sure the next rq can push to this rq */
1860 if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr)
1867 #define RT_PUSH_IPI_EXECUTING 1
1868 #define RT_PUSH_IPI_RESTART 2
1870 static void tell_cpu_to_push(struct rq *rq)
1874 if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
1875 raw_spin_lock(&rq->rt.push_lock);
1876 /* Make sure it's still executing */
1877 if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
1879 * Tell the IPI to restart the loop as things have
1880 * changed since it started.
1882 rq->rt.push_flags |= RT_PUSH_IPI_RESTART;
1883 raw_spin_unlock(&rq->rt.push_lock);
1886 raw_spin_unlock(&rq->rt.push_lock);
1889 /* When here, there's no IPI going around */
1891 rq->rt.push_cpu = rq->cpu;
1892 cpu = find_next_push_cpu(rq);
1893 if (cpu >= nr_cpu_ids)
1896 rq->rt.push_flags = RT_PUSH_IPI_EXECUTING;
1898 irq_work_queue_on(&rq->rt.push_work, cpu);
1901 /* Called from hardirq context */
1902 static void try_to_push_tasks(void *arg)
1904 struct rt_rq *rt_rq = arg;
1905 struct rq *rq, *src_rq;
1909 this_cpu = rt_rq->push_cpu;
1911 /* Paranoid check */
1912 BUG_ON(this_cpu != smp_processor_id());
1914 rq = cpu_rq(this_cpu);
1915 src_rq = rq_of_rt_rq(rt_rq);
1918 if (has_pushable_tasks(rq)) {
1919 raw_spin_lock(&rq->lock);
1921 raw_spin_unlock(&rq->lock);
1924 /* Pass the IPI to the next rt overloaded queue */
1925 raw_spin_lock(&rt_rq->push_lock);
1927 * If the source queue changed since the IPI went out,
1928 * we need to restart the search from that CPU again.
1930 if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) {
1931 rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART;
1932 rt_rq->push_cpu = src_rq->cpu;
1935 cpu = find_next_push_cpu(src_rq);
1937 if (cpu >= nr_cpu_ids)
1938 rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING;
1939 raw_spin_unlock(&rt_rq->push_lock);
1941 if (cpu >= nr_cpu_ids)
1945 * It is possible that a restart caused this CPU to be
1946 * chosen again. Don't bother with an IPI, just see if we
1947 * have more to push.
1949 if (unlikely(cpu == rq->cpu))
1952 /* Try the next RT overloaded CPU */
1953 irq_work_queue_on(&rt_rq->push_work, cpu);
1956 static void push_irq_work_func(struct irq_work *work)
1958 struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work);
1960 try_to_push_tasks(rt_rq);
1962 #endif /* HAVE_RT_PUSH_IPI */
1964 static void pull_rt_task(struct rq *this_rq)
1966 int this_cpu = this_rq->cpu, cpu;
1967 bool resched = false;
1968 struct task_struct *p;
1971 if (likely(!rt_overloaded(this_rq)))
1975 * Match the barrier from rt_set_overloaded; this guarantees that if we
1976 * see overloaded we must also see the rto_mask bit.
1980 #ifdef HAVE_RT_PUSH_IPI
1981 if (sched_feat(RT_PUSH_IPI)) {
1982 tell_cpu_to_push(this_rq);
1987 for_each_cpu(cpu, this_rq->rd->rto_mask) {
1988 if (this_cpu == cpu)
1991 src_rq = cpu_rq(cpu);
1994 * Don't bother taking the src_rq->lock if the next highest
1995 * task is known to be lower-priority than our current task.
1996 * This may look racy, but if this value is about to go
1997 * logically higher, the src_rq will push this task away.
1998 * And if its going logically lower, we do not care
2000 if (src_rq->rt.highest_prio.next >=
2001 this_rq->rt.highest_prio.curr)
2005 * We can potentially drop this_rq's lock in
2006 * double_lock_balance, and another CPU could
2009 double_lock_balance(this_rq, src_rq);
2012 * We can pull only a task, which is pushable
2013 * on its rq, and no others.
2015 p = pick_highest_pushable_task(src_rq, this_cpu);
2018 * Do we have an RT task that preempts
2019 * the to-be-scheduled task?
2021 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
2022 WARN_ON(p == src_rq->curr);
2023 WARN_ON(!task_on_rq_queued(p));
2026 * There's a chance that p is higher in priority
2027 * than what's currently running on its cpu.
2028 * This is just that p is wakeing up and hasn't
2029 * had a chance to schedule. We only pull
2030 * p if it is lower in priority than the
2031 * current task on the run queue
2033 if (p->prio < src_rq->curr->prio)
2038 deactivate_task(src_rq, p, 0);
2039 set_task_cpu(p, this_cpu);
2040 activate_task(this_rq, p, 0);
2042 * We continue with the search, just in
2043 * case there's an even higher prio task
2044 * in another runqueue. (low likelihood
2049 double_unlock_balance(this_rq, src_rq);
2053 resched_curr(this_rq);
2057 * If we are not running and we are not going to reschedule soon, we should
2058 * try to push tasks away now
2060 static void task_woken_rt(struct rq *rq, struct task_struct *p)
2062 if (!task_running(rq, p) &&
2063 !test_tsk_need_resched(rq->curr) &&
2064 tsk_nr_cpus_allowed(p) > 1 &&
2065 (dl_task(rq->curr) || rt_task(rq->curr)) &&
2066 (tsk_nr_cpus_allowed(rq->curr) < 2 ||
2067 rq->curr->prio <= p->prio))
2071 /* Assumes rq->lock is held */
2072 static void rq_online_rt(struct rq *rq)
2074 if (rq->rt.overloaded)
2075 rt_set_overload(rq);
2077 __enable_runtime(rq);
2079 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
2082 /* Assumes rq->lock is held */
2083 static void rq_offline_rt(struct rq *rq)
2085 if (rq->rt.overloaded)
2086 rt_clear_overload(rq);
2088 __disable_runtime(rq);
2090 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
2094 * When switch from the rt queue, we bring ourselves to a position
2095 * that we might want to pull RT tasks from other runqueues.
2097 static void switched_from_rt(struct rq *rq, struct task_struct *p)
2100 * If there are other RT tasks then we will reschedule
2101 * and the scheduling of the other RT tasks will handle
2102 * the balancing. But if we are the last RT task
2103 * we may need to handle the pulling of RT tasks
2106 if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
2109 queue_pull_task(rq);
2112 void __init init_sched_rt_class(void)
2116 for_each_possible_cpu(i) {
2117 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
2118 GFP_KERNEL, cpu_to_node(i));
2121 #endif /* CONFIG_SMP */
2124 * When switching a task to RT, we may overload the runqueue
2125 * with RT tasks. In this case we try to push them off to
2128 static void switched_to_rt(struct rq *rq, struct task_struct *p)
2131 * If we are already running, then there's nothing
2132 * that needs to be done. But if we are not running
2133 * we may need to preempt the current running task.
2134 * If that current running task is also an RT task
2135 * then see if we can move to another run queue.
2137 if (task_on_rq_queued(p) && rq->curr != p) {
2139 if (tsk_nr_cpus_allowed(p) > 1 && rq->rt.overloaded)
2140 queue_push_tasks(rq);
2142 if (p->prio < rq->curr->prio)
2144 #endif /* CONFIG_SMP */
2149 * Priority of the task has changed. This may cause
2150 * us to initiate a push or pull.
2153 prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
2155 if (!task_on_rq_queued(p))
2158 if (rq->curr == p) {
2161 * If our priority decreases while running, we
2162 * may need to pull tasks to this runqueue.
2164 if (oldprio < p->prio)
2165 queue_pull_task(rq);
2168 * If there's a higher priority task waiting to run
2171 if (p->prio > rq->rt.highest_prio.curr)
2174 /* For UP simply resched on drop of prio */
2175 if (oldprio < p->prio)
2177 #endif /* CONFIG_SMP */
2180 * This task is not running, but if it is
2181 * greater than the current running task
2184 if (p->prio < rq->curr->prio)
2189 static void watchdog(struct rq *rq, struct task_struct *p)
2191 unsigned long soft, hard;
2193 /* max may change after cur was read, this will be fixed next tick */
2194 soft = task_rlimit(p, RLIMIT_RTTIME);
2195 hard = task_rlimit_max(p, RLIMIT_RTTIME);
2197 if (soft != RLIM_INFINITY) {
2200 if (p->rt.watchdog_stamp != jiffies) {
2202 p->rt.watchdog_stamp = jiffies;
2205 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
2206 if (p->rt.timeout > next)
2207 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
2211 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
2213 struct sched_rt_entity *rt_se = &p->rt;
2220 * RR tasks need a special form of timeslice management.
2221 * FIFO tasks have no timeslices.
2223 if (p->policy != SCHED_RR)
2226 if (--p->rt.time_slice)
2229 p->rt.time_slice = sched_rr_timeslice;
2232 * Requeue to the end of queue if we (and all of our ancestors) are not
2233 * the only element on the queue
2235 for_each_sched_rt_entity(rt_se) {
2236 if (rt_se->run_list.prev != rt_se->run_list.next) {
2237 requeue_task_rt(rq, p, 0);
2244 static void set_curr_task_rt(struct rq *rq)
2246 struct task_struct *p = rq->curr;
2248 p->se.exec_start = rq_clock_task(rq);
2250 /* The running task is never eligible for pushing */
2251 dequeue_pushable_task(rq, p);
2254 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
2257 * Time slice is 0 for SCHED_FIFO tasks
2259 if (task->policy == SCHED_RR)
2260 return sched_rr_timeslice;
2265 const struct sched_class rt_sched_class = {
2266 .next = &fair_sched_class,
2267 .enqueue_task = enqueue_task_rt,
2268 .dequeue_task = dequeue_task_rt,
2269 .yield_task = yield_task_rt,
2271 .check_preempt_curr = check_preempt_curr_rt,
2273 .pick_next_task = pick_next_task_rt,
2274 .put_prev_task = put_prev_task_rt,
2277 .select_task_rq = select_task_rq_rt,
2279 .set_cpus_allowed = set_cpus_allowed_common,
2280 .rq_online = rq_online_rt,
2281 .rq_offline = rq_offline_rt,
2282 .task_woken = task_woken_rt,
2283 .switched_from = switched_from_rt,
2286 .set_curr_task = set_curr_task_rt,
2287 .task_tick = task_tick_rt,
2289 .get_rr_interval = get_rr_interval_rt,
2291 .prio_changed = prio_changed_rt,
2292 .switched_to = switched_to_rt,
2294 .update_curr = update_curr_rt,
2297 #ifdef CONFIG_SCHED_DEBUG
2298 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
2300 void print_rt_stats(struct seq_file *m, int cpu)
2303 struct rt_rq *rt_rq;
2306 for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
2307 print_rt_rq(m, cpu, rt_rq);
2310 #endif /* CONFIG_SCHED_DEBUG */