crypto: omap-aes - initialize aes module once per request
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / sched_rt.c
blobbea7d79f7e9ca958bba514cbd8eb48ceab47bab3
1 /*
2 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
3 * policies)
4 */
6 #ifdef CONFIG_RT_GROUP_SCHED
8 #define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
10 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
12 #ifdef CONFIG_SCHED_DEBUG
13 WARN_ON_ONCE(!rt_entity_is_task(rt_se));
14 #endif
15 return container_of(rt_se, struct task_struct, rt);
18 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
20 return rt_rq->rq;
23 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
25 return rt_se->rt_rq;
28 #else /* CONFIG_RT_GROUP_SCHED */
30 #define rt_entity_is_task(rt_se) (1)
32 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
34 return container_of(rt_se, struct task_struct, rt);
37 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
39 return container_of(rt_rq, struct rq, rt);
42 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
44 struct task_struct *p = rt_task_of(rt_se);
45 struct rq *rq = task_rq(p);
47 return &rq->rt;
50 #endif /* CONFIG_RT_GROUP_SCHED */
52 #ifdef CONFIG_SMP
54 static inline int rt_overloaded(struct rq *rq)
56 return atomic_read(&rq->rd->rto_count);
59 static inline void rt_set_overload(struct rq *rq)
61 if (!rq->online)
62 return;
64 cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
66 * Make sure the mask is visible before we set
67 * the overload count. That is checked to determine
68 * if we should look at the mask. It would be a shame
69 * if we looked at the mask, but the mask was not
70 * updated yet.
72 wmb();
73 atomic_inc(&rq->rd->rto_count);
76 static inline void rt_clear_overload(struct rq *rq)
78 if (!rq->online)
79 return;
81 /* the order here really doesn't matter */
82 atomic_dec(&rq->rd->rto_count);
83 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
86 static void update_rt_migration(struct rt_rq *rt_rq)
88 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
89 if (!rt_rq->overloaded) {
90 rt_set_overload(rq_of_rt_rq(rt_rq));
91 rt_rq->overloaded = 1;
93 } else if (rt_rq->overloaded) {
94 rt_clear_overload(rq_of_rt_rq(rt_rq));
95 rt_rq->overloaded = 0;
99 static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
101 if (!rt_entity_is_task(rt_se))
102 return;
104 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
106 rt_rq->rt_nr_total++;
107 if (rt_se->nr_cpus_allowed > 1)
108 rt_rq->rt_nr_migratory++;
110 update_rt_migration(rt_rq);
113 static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
115 if (!rt_entity_is_task(rt_se))
116 return;
118 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
120 rt_rq->rt_nr_total--;
121 if (rt_se->nr_cpus_allowed > 1)
122 rt_rq->rt_nr_migratory--;
124 update_rt_migration(rt_rq);
127 static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
129 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
130 plist_node_init(&p->pushable_tasks, p->prio);
131 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
134 static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
136 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
139 static inline int has_pushable_tasks(struct rq *rq)
141 return !plist_head_empty(&rq->rt.pushable_tasks);
144 #else
146 static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
150 static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
154 static inline
155 void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
159 static inline
160 void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
164 #endif /* CONFIG_SMP */
166 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
168 return !list_empty(&rt_se->run_list);
171 #ifdef CONFIG_RT_GROUP_SCHED
173 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
175 if (!rt_rq->tg)
176 return RUNTIME_INF;
178 return rt_rq->rt_runtime;
181 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
183 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
186 #define for_each_leaf_rt_rq(rt_rq, rq) \
187 list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
189 #define for_each_sched_rt_entity(rt_se) \
190 for (; rt_se; rt_se = rt_se->parent)
192 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
194 return rt_se->my_q;
197 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
198 static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
200 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
202 int this_cpu = smp_processor_id();
203 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
204 struct sched_rt_entity *rt_se;
206 rt_se = rt_rq->tg->rt_se[this_cpu];
208 if (rt_rq->rt_nr_running) {
209 if (rt_se && !on_rt_rq(rt_se))
210 enqueue_rt_entity(rt_se, false);
211 if (rt_rq->highest_prio.curr < curr->prio)
212 resched_task(curr);
216 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
218 int this_cpu = smp_processor_id();
219 struct sched_rt_entity *rt_se;
221 rt_se = rt_rq->tg->rt_se[this_cpu];
223 if (rt_se && on_rt_rq(rt_se))
224 dequeue_rt_entity(rt_se);
227 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
229 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
232 static int rt_se_boosted(struct sched_rt_entity *rt_se)
234 struct rt_rq *rt_rq = group_rt_rq(rt_se);
235 struct task_struct *p;
237 if (rt_rq)
238 return !!rt_rq->rt_nr_boosted;
240 p = rt_task_of(rt_se);
241 return p->prio != p->normal_prio;
244 #ifdef CONFIG_SMP
245 static inline const struct cpumask *sched_rt_period_mask(void)
247 return cpu_rq(smp_processor_id())->rd->span;
249 #else
250 static inline const struct cpumask *sched_rt_period_mask(void)
252 return cpu_online_mask;
254 #endif
256 static inline
257 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
259 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
262 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
264 return &rt_rq->tg->rt_bandwidth;
267 #else /* !CONFIG_RT_GROUP_SCHED */
269 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
271 return rt_rq->rt_runtime;
274 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
276 return ktime_to_ns(def_rt_bandwidth.rt_period);
279 #define for_each_leaf_rt_rq(rt_rq, rq) \
280 for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
282 #define for_each_sched_rt_entity(rt_se) \
283 for (; rt_se; rt_se = NULL)
285 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
287 return NULL;
290 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
292 if (rt_rq->rt_nr_running)
293 resched_task(rq_of_rt_rq(rt_rq)->curr);
296 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
300 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
302 return rt_rq->rt_throttled;
305 static inline const struct cpumask *sched_rt_period_mask(void)
307 return cpu_online_mask;
310 static inline
311 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
313 return &cpu_rq(cpu)->rt;
316 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
318 return &def_rt_bandwidth;
321 #endif /* CONFIG_RT_GROUP_SCHED */
323 #ifdef CONFIG_SMP
325 * We ran out of runtime, see if we can borrow some from our neighbours.
327 static int do_balance_runtime(struct rt_rq *rt_rq)
329 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
330 struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
331 int i, weight, more = 0;
332 u64 rt_period;
334 weight = cpumask_weight(rd->span);
336 raw_spin_lock(&rt_b->rt_runtime_lock);
337 rt_period = ktime_to_ns(rt_b->rt_period);
338 for_each_cpu(i, rd->span) {
339 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
340 s64 diff;
342 if (iter == rt_rq)
343 continue;
345 raw_spin_lock(&iter->rt_runtime_lock);
347 * Either all rqs have inf runtime and there's nothing to steal
348 * or __disable_runtime() below sets a specific rq to inf to
349 * indicate its been disabled and disalow stealing.
351 if (iter->rt_runtime == RUNTIME_INF)
352 goto next;
355 * From runqueues with spare time, take 1/n part of their
356 * spare time, but no more than our period.
358 diff = iter->rt_runtime - iter->rt_time;
359 if (diff > 0) {
360 diff = div_u64((u64)diff, weight);
361 if (rt_rq->rt_runtime + diff > rt_period)
362 diff = rt_period - rt_rq->rt_runtime;
363 iter->rt_runtime -= diff;
364 rt_rq->rt_runtime += diff;
365 more = 1;
366 if (rt_rq->rt_runtime == rt_period) {
367 raw_spin_unlock(&iter->rt_runtime_lock);
368 break;
371 next:
372 raw_spin_unlock(&iter->rt_runtime_lock);
374 raw_spin_unlock(&rt_b->rt_runtime_lock);
376 return more;
380 * Ensure this RQ takes back all the runtime it lend to its neighbours.
382 static void __disable_runtime(struct rq *rq)
384 struct root_domain *rd = rq->rd;
385 struct rt_rq *rt_rq;
387 if (unlikely(!scheduler_running))
388 return;
390 for_each_leaf_rt_rq(rt_rq, rq) {
391 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
392 s64 want;
393 int i;
395 raw_spin_lock(&rt_b->rt_runtime_lock);
396 raw_spin_lock(&rt_rq->rt_runtime_lock);
398 * Either we're all inf and nobody needs to borrow, or we're
399 * already disabled and thus have nothing to do, or we have
400 * exactly the right amount of runtime to take out.
402 if (rt_rq->rt_runtime == RUNTIME_INF ||
403 rt_rq->rt_runtime == rt_b->rt_runtime)
404 goto balanced;
405 raw_spin_unlock(&rt_rq->rt_runtime_lock);
408 * Calculate the difference between what we started out with
409 * and what we current have, that's the amount of runtime
410 * we lend and now have to reclaim.
412 want = rt_b->rt_runtime - rt_rq->rt_runtime;
415 * Greedy reclaim, take back as much as we can.
417 for_each_cpu(i, rd->span) {
418 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
419 s64 diff;
422 * Can't reclaim from ourselves or disabled runqueues.
424 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
425 continue;
427 raw_spin_lock(&iter->rt_runtime_lock);
428 if (want > 0) {
429 diff = min_t(s64, iter->rt_runtime, want);
430 iter->rt_runtime -= diff;
431 want -= diff;
432 } else {
433 iter->rt_runtime -= want;
434 want -= want;
436 raw_spin_unlock(&iter->rt_runtime_lock);
438 if (!want)
439 break;
442 raw_spin_lock(&rt_rq->rt_runtime_lock);
444 * We cannot be left wanting - that would mean some runtime
445 * leaked out of the system.
447 BUG_ON(want);
448 balanced:
450 * Disable all the borrow logic by pretending we have inf
451 * runtime - in which case borrowing doesn't make sense.
453 rt_rq->rt_runtime = RUNTIME_INF;
454 raw_spin_unlock(&rt_rq->rt_runtime_lock);
455 raw_spin_unlock(&rt_b->rt_runtime_lock);
459 static void disable_runtime(struct rq *rq)
461 unsigned long flags;
463 raw_spin_lock_irqsave(&rq->lock, flags);
464 __disable_runtime(rq);
465 raw_spin_unlock_irqrestore(&rq->lock, flags);
468 static void __enable_runtime(struct rq *rq)
470 struct rt_rq *rt_rq;
472 if (unlikely(!scheduler_running))
473 return;
476 * Reset each runqueue's bandwidth settings
478 for_each_leaf_rt_rq(rt_rq, rq) {
479 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
481 raw_spin_lock(&rt_b->rt_runtime_lock);
482 raw_spin_lock(&rt_rq->rt_runtime_lock);
483 rt_rq->rt_runtime = rt_b->rt_runtime;
484 rt_rq->rt_time = 0;
485 rt_rq->rt_throttled = 0;
486 raw_spin_unlock(&rt_rq->rt_runtime_lock);
487 raw_spin_unlock(&rt_b->rt_runtime_lock);
491 static void enable_runtime(struct rq *rq)
493 unsigned long flags;
495 raw_spin_lock_irqsave(&rq->lock, flags);
496 __enable_runtime(rq);
497 raw_spin_unlock_irqrestore(&rq->lock, flags);
500 static int balance_runtime(struct rt_rq *rt_rq)
502 int more = 0;
504 if (rt_rq->rt_time > rt_rq->rt_runtime) {
505 raw_spin_unlock(&rt_rq->rt_runtime_lock);
506 more = do_balance_runtime(rt_rq);
507 raw_spin_lock(&rt_rq->rt_runtime_lock);
510 return more;
512 #else /* !CONFIG_SMP */
513 static inline int balance_runtime(struct rt_rq *rt_rq)
515 return 0;
517 #endif /* CONFIG_SMP */
519 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
521 int i, idle = 1;
522 const struct cpumask *span;
524 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
525 return 1;
527 span = sched_rt_period_mask();
528 for_each_cpu(i, span) {
529 int enqueue = 0;
530 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
531 struct rq *rq = rq_of_rt_rq(rt_rq);
533 raw_spin_lock(&rq->lock);
534 if (rt_rq->rt_time) {
535 u64 runtime;
537 raw_spin_lock(&rt_rq->rt_runtime_lock);
538 if (rt_rq->rt_throttled)
539 balance_runtime(rt_rq);
540 runtime = rt_rq->rt_runtime;
541 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
542 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
543 rt_rq->rt_throttled = 0;
544 enqueue = 1;
546 if (rt_rq->rt_time || rt_rq->rt_nr_running)
547 idle = 0;
548 raw_spin_unlock(&rt_rq->rt_runtime_lock);
549 } else if (rt_rq->rt_nr_running)
550 idle = 0;
552 if (enqueue)
553 sched_rt_rq_enqueue(rt_rq);
554 raw_spin_unlock(&rq->lock);
557 return idle;
560 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
562 #ifdef CONFIG_RT_GROUP_SCHED
563 struct rt_rq *rt_rq = group_rt_rq(rt_se);
565 if (rt_rq)
566 return rt_rq->highest_prio.curr;
567 #endif
569 return rt_task_of(rt_se)->prio;
572 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
574 u64 runtime = sched_rt_runtime(rt_rq);
576 if (rt_rq->rt_throttled)
577 return rt_rq_throttled(rt_rq);
579 if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
580 return 0;
582 balance_runtime(rt_rq);
583 runtime = sched_rt_runtime(rt_rq);
584 if (runtime == RUNTIME_INF)
585 return 0;
587 if (rt_rq->rt_time > runtime) {
588 rt_rq->rt_throttled = 1;
589 if (rt_rq_throttled(rt_rq)) {
590 sched_rt_rq_dequeue(rt_rq);
591 return 1;
595 return 0;
599 * Update the current task's runtime statistics. Skip current tasks that
600 * are not in our scheduling class.
602 static void update_curr_rt(struct rq *rq)
604 struct task_struct *curr = rq->curr;
605 struct sched_rt_entity *rt_se = &curr->rt;
606 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
607 u64 delta_exec;
609 if (!task_has_rt_policy(curr))
610 return;
612 delta_exec = rq->clock_task - curr->se.exec_start;
613 if (unlikely((s64)delta_exec < 0))
614 delta_exec = 0;
616 schedstat_set(curr->se.statistics.exec_max, max(curr->se.statistics.exec_max, delta_exec));
618 curr->se.sum_exec_runtime += delta_exec;
619 account_group_exec_runtime(curr, delta_exec);
621 curr->se.exec_start = rq->clock_task;
622 cpuacct_charge(curr, delta_exec);
624 sched_rt_avg_update(rq, delta_exec);
626 if (!rt_bandwidth_enabled())
627 return;
629 for_each_sched_rt_entity(rt_se) {
630 rt_rq = rt_rq_of_se(rt_se);
632 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
633 raw_spin_lock(&rt_rq->rt_runtime_lock);
634 rt_rq->rt_time += delta_exec;
635 if (sched_rt_runtime_exceeded(rt_rq))
636 resched_task(curr);
637 raw_spin_unlock(&rt_rq->rt_runtime_lock);
642 #if defined CONFIG_SMP
644 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu);
646 static inline int next_prio(struct rq *rq)
648 struct task_struct *next = pick_next_highest_task_rt(rq, rq->cpu);
650 if (next && rt_prio(next->prio))
651 return next->prio;
652 else
653 return MAX_RT_PRIO;
656 static void
657 inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
659 struct rq *rq = rq_of_rt_rq(rt_rq);
661 if (prio < prev_prio) {
664 * If the new task is higher in priority than anything on the
665 * run-queue, we know that the previous high becomes our
666 * next-highest.
668 rt_rq->highest_prio.next = prev_prio;
670 if (rq->online)
671 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
673 } else if (prio == rt_rq->highest_prio.curr)
675 * If the next task is equal in priority to the highest on
676 * the run-queue, then we implicitly know that the next highest
677 * task cannot be any lower than current
679 rt_rq->highest_prio.next = prio;
680 else if (prio < rt_rq->highest_prio.next)
682 * Otherwise, we need to recompute next-highest
684 rt_rq->highest_prio.next = next_prio(rq);
687 static void
688 dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
690 struct rq *rq = rq_of_rt_rq(rt_rq);
692 if (rt_rq->rt_nr_running && (prio <= rt_rq->highest_prio.next))
693 rt_rq->highest_prio.next = next_prio(rq);
695 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
696 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
699 #else /* CONFIG_SMP */
701 static inline
702 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
703 static inline
704 void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
706 #endif /* CONFIG_SMP */
708 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
709 static void
710 inc_rt_prio(struct rt_rq *rt_rq, int prio)
712 int prev_prio = rt_rq->highest_prio.curr;
714 if (prio < prev_prio)
715 rt_rq->highest_prio.curr = prio;
717 inc_rt_prio_smp(rt_rq, prio, prev_prio);
720 static void
721 dec_rt_prio(struct rt_rq *rt_rq, int prio)
723 int prev_prio = rt_rq->highest_prio.curr;
725 if (rt_rq->rt_nr_running) {
727 WARN_ON(prio < prev_prio);
730 * This may have been our highest task, and therefore
731 * we may have some recomputation to do
733 if (prio == prev_prio) {
734 struct rt_prio_array *array = &rt_rq->active;
736 rt_rq->highest_prio.curr =
737 sched_find_first_bit(array->bitmap);
740 } else
741 rt_rq->highest_prio.curr = MAX_RT_PRIO;
743 dec_rt_prio_smp(rt_rq, prio, prev_prio);
746 #else
748 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
749 static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
751 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
753 #ifdef CONFIG_RT_GROUP_SCHED
755 static void
756 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
758 if (rt_se_boosted(rt_se))
759 rt_rq->rt_nr_boosted++;
761 if (rt_rq->tg)
762 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
765 static void
766 dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
768 if (rt_se_boosted(rt_se))
769 rt_rq->rt_nr_boosted--;
771 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
774 #else /* CONFIG_RT_GROUP_SCHED */
776 static void
777 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
779 start_rt_bandwidth(&def_rt_bandwidth);
782 static inline
783 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
785 #endif /* CONFIG_RT_GROUP_SCHED */
787 static inline
788 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
790 int prio = rt_se_prio(rt_se);
792 WARN_ON(!rt_prio(prio));
793 rt_rq->rt_nr_running++;
795 inc_rt_prio(rt_rq, prio);
796 inc_rt_migration(rt_se, rt_rq);
797 inc_rt_group(rt_se, rt_rq);
800 static inline
801 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
803 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
804 WARN_ON(!rt_rq->rt_nr_running);
805 rt_rq->rt_nr_running--;
807 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
808 dec_rt_migration(rt_se, rt_rq);
809 dec_rt_group(rt_se, rt_rq);
812 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
814 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
815 struct rt_prio_array *array = &rt_rq->active;
816 struct rt_rq *group_rq = group_rt_rq(rt_se);
817 struct list_head *queue = array->queue + rt_se_prio(rt_se);
820 * Don't enqueue the group if its throttled, or when empty.
821 * The latter is a consequence of the former when a child group
822 * get throttled and the current group doesn't have any other
823 * active members.
825 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
826 return;
828 if (head)
829 list_add(&rt_se->run_list, queue);
830 else
831 list_add_tail(&rt_se->run_list, queue);
832 __set_bit(rt_se_prio(rt_se), array->bitmap);
834 inc_rt_tasks(rt_se, rt_rq);
837 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
839 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
840 struct rt_prio_array *array = &rt_rq->active;
842 list_del_init(&rt_se->run_list);
843 if (list_empty(array->queue + rt_se_prio(rt_se)))
844 __clear_bit(rt_se_prio(rt_se), array->bitmap);
846 dec_rt_tasks(rt_se, rt_rq);
850 * Because the prio of an upper entry depends on the lower
851 * entries, we must remove entries top - down.
853 static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
855 struct sched_rt_entity *back = NULL;
857 for_each_sched_rt_entity(rt_se) {
858 rt_se->back = back;
859 back = rt_se;
862 for (rt_se = back; rt_se; rt_se = rt_se->back) {
863 if (on_rt_rq(rt_se))
864 __dequeue_rt_entity(rt_se);
868 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
870 dequeue_rt_stack(rt_se);
871 for_each_sched_rt_entity(rt_se)
872 __enqueue_rt_entity(rt_se, head);
875 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
877 dequeue_rt_stack(rt_se);
879 for_each_sched_rt_entity(rt_se) {
880 struct rt_rq *rt_rq = group_rt_rq(rt_se);
882 if (rt_rq && rt_rq->rt_nr_running)
883 __enqueue_rt_entity(rt_se, false);
888 * Adding/removing a task to/from a priority array:
890 static void
891 enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
893 struct sched_rt_entity *rt_se = &p->rt;
895 if (flags & ENQUEUE_WAKEUP)
896 rt_se->timeout = 0;
898 enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
900 if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
901 enqueue_pushable_task(rq, p);
904 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
906 struct sched_rt_entity *rt_se = &p->rt;
908 update_curr_rt(rq);
909 dequeue_rt_entity(rt_se);
911 dequeue_pushable_task(rq, p);
915 * Put task to the end of the run list without the overhead of dequeue
916 * followed by enqueue.
918 static void
919 requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
921 if (on_rt_rq(rt_se)) {
922 struct rt_prio_array *array = &rt_rq->active;
923 struct list_head *queue = array->queue + rt_se_prio(rt_se);
925 if (head)
926 list_move(&rt_se->run_list, queue);
927 else
928 list_move_tail(&rt_se->run_list, queue);
932 static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
934 struct sched_rt_entity *rt_se = &p->rt;
935 struct rt_rq *rt_rq;
937 for_each_sched_rt_entity(rt_se) {
938 rt_rq = rt_rq_of_se(rt_se);
939 requeue_rt_entity(rt_rq, rt_se, head);
943 static void yield_task_rt(struct rq *rq)
945 requeue_task_rt(rq, rq->curr, 0);
948 #ifdef CONFIG_SMP
949 static int find_lowest_rq(struct task_struct *task);
951 static int
952 select_task_rq_rt(struct rq *rq, struct task_struct *p, int sd_flag, int flags)
954 if (sd_flag != SD_BALANCE_WAKE)
955 return smp_processor_id();
958 * If the current task is an RT task, then
959 * try to see if we can wake this RT task up on another
960 * runqueue. Otherwise simply start this RT task
961 * on its current runqueue.
963 * We want to avoid overloading runqueues. If the woken
964 * task is a higher priority, then it will stay on this CPU
965 * and the lower prio task should be moved to another CPU.
966 * Even though this will probably make the lower prio task
967 * lose its cache, we do not want to bounce a higher task
968 * around just because it gave up its CPU, perhaps for a
969 * lock?
971 * For equal prio tasks, we just let the scheduler sort it out.
973 if (unlikely(rt_task(rq->curr)) &&
974 (rq->curr->rt.nr_cpus_allowed < 2 ||
975 rq->curr->prio < p->prio) &&
976 (p->rt.nr_cpus_allowed > 1)) {
977 int cpu = find_lowest_rq(p);
979 return (cpu == -1) ? task_cpu(p) : cpu;
983 * Otherwise, just let it ride on the affined RQ and the
984 * post-schedule router will push the preempted task away
986 return task_cpu(p);
989 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
991 if (rq->curr->rt.nr_cpus_allowed == 1)
992 return;
994 if (p->rt.nr_cpus_allowed != 1
995 && cpupri_find(&rq->rd->cpupri, p, NULL))
996 return;
998 if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
999 return;
1002 * There appears to be other cpus that can accept
1003 * current and none to run 'p', so lets reschedule
1004 * to try and push current away:
1006 requeue_task_rt(rq, p, 1);
1007 resched_task(rq->curr);
1010 #endif /* CONFIG_SMP */
1013 * Preempt the current task with a newly woken task if needed:
1015 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1017 if (p->prio < rq->curr->prio) {
1018 resched_task(rq->curr);
1019 return;
1022 #ifdef CONFIG_SMP
1024 * If:
1026 * - the newly woken task is of equal priority to the current task
1027 * - the newly woken task is non-migratable while current is migratable
1028 * - current will be preempted on the next reschedule
1030 * we should check to see if current can readily move to a different
1031 * cpu. If so, we will reschedule to allow the push logic to try
1032 * to move current somewhere else, making room for our non-migratable
1033 * task.
1035 if (p->prio == rq->curr->prio && !need_resched())
1036 check_preempt_equal_prio(rq, p);
1037 #endif
1040 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1041 struct rt_rq *rt_rq)
1043 struct rt_prio_array *array = &rt_rq->active;
1044 struct sched_rt_entity *next = NULL;
1045 struct list_head *queue;
1046 int idx;
1048 idx = sched_find_first_bit(array->bitmap);
1049 BUG_ON(idx >= MAX_RT_PRIO);
1051 queue = array->queue + idx;
1052 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1054 return next;
1057 static struct task_struct *_pick_next_task_rt(struct rq *rq)
1059 struct sched_rt_entity *rt_se;
1060 struct task_struct *p;
1061 struct rt_rq *rt_rq;
1063 rt_rq = &rq->rt;
1065 if (unlikely(!rt_rq->rt_nr_running))
1066 return NULL;
1068 if (rt_rq_throttled(rt_rq))
1069 return NULL;
1071 do {
1072 rt_se = pick_next_rt_entity(rq, rt_rq);
1073 BUG_ON(!rt_se);
1074 rt_rq = group_rt_rq(rt_se);
1075 } while (rt_rq);
1077 p = rt_task_of(rt_se);
1078 p->se.exec_start = rq->clock_task;
1080 return p;
1083 static struct task_struct *pick_next_task_rt(struct rq *rq)
1085 struct task_struct *p = _pick_next_task_rt(rq);
1087 /* The running task is never eligible for pushing */
1088 if (p)
1089 dequeue_pushable_task(rq, p);
1091 #ifdef CONFIG_SMP
1093 * We detect this state here so that we can avoid taking the RQ
1094 * lock again later if there is no need to push
1096 rq->post_schedule = has_pushable_tasks(rq);
1097 #endif
1099 return p;
1102 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1104 update_curr_rt(rq);
1105 p->se.exec_start = 0;
1108 * The previous task needs to be made eligible for pushing
1109 * if it is still active
1111 if (p->se.on_rq && p->rt.nr_cpus_allowed > 1)
1112 enqueue_pushable_task(rq, p);
1115 #ifdef CONFIG_SMP
1117 /* Only try algorithms three times */
1118 #define RT_MAX_TRIES 3
1120 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
1122 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1124 if (!task_running(rq, p) &&
1125 (cpu < 0 || cpumask_test_cpu(cpu, &p->cpus_allowed)) &&
1126 (p->rt.nr_cpus_allowed > 1))
1127 return 1;
1128 return 0;
1131 /* Return the second highest RT task, NULL otherwise */
1132 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
1134 struct task_struct *next = NULL;
1135 struct sched_rt_entity *rt_se;
1136 struct rt_prio_array *array;
1137 struct rt_rq *rt_rq;
1138 int idx;
1140 for_each_leaf_rt_rq(rt_rq, rq) {
1141 array = &rt_rq->active;
1142 idx = sched_find_first_bit(array->bitmap);
1143 next_idx:
1144 if (idx >= MAX_RT_PRIO)
1145 continue;
1146 if (next && next->prio < idx)
1147 continue;
1148 list_for_each_entry(rt_se, array->queue + idx, run_list) {
1149 struct task_struct *p;
1151 if (!rt_entity_is_task(rt_se))
1152 continue;
1154 p = rt_task_of(rt_se);
1155 if (pick_rt_task(rq, p, cpu)) {
1156 next = p;
1157 break;
1160 if (!next) {
1161 idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
1162 goto next_idx;
1166 return next;
1169 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1171 static int find_lowest_rq(struct task_struct *task)
1173 struct sched_domain *sd;
1174 struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
1175 int this_cpu = smp_processor_id();
1176 int cpu = task_cpu(task);
1178 if (task->rt.nr_cpus_allowed == 1)
1179 return -1; /* No other targets possible */
1181 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1182 return -1; /* No targets found */
1185 * At this point we have built a mask of cpus representing the
1186 * lowest priority tasks in the system. Now we want to elect
1187 * the best one based on our affinity and topology.
1189 * We prioritize the last cpu that the task executed on since
1190 * it is most likely cache-hot in that location.
1192 if (cpumask_test_cpu(cpu, lowest_mask))
1193 return cpu;
1196 * Otherwise, we consult the sched_domains span maps to figure
1197 * out which cpu is logically closest to our hot cache data.
1199 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1200 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1202 for_each_domain(cpu, sd) {
1203 if (sd->flags & SD_WAKE_AFFINE) {
1204 int best_cpu;
1207 * "this_cpu" is cheaper to preempt than a
1208 * remote processor.
1210 if (this_cpu != -1 &&
1211 cpumask_test_cpu(this_cpu, sched_domain_span(sd)))
1212 return this_cpu;
1214 best_cpu = cpumask_first_and(lowest_mask,
1215 sched_domain_span(sd));
1216 if (best_cpu < nr_cpu_ids)
1217 return best_cpu;
1222 * And finally, if there were no matches within the domains
1223 * just give the caller *something* to work with from the compatible
1224 * locations.
1226 if (this_cpu != -1)
1227 return this_cpu;
1229 cpu = cpumask_any(lowest_mask);
1230 if (cpu < nr_cpu_ids)
1231 return cpu;
1232 return -1;
1235 /* Will lock the rq it finds */
1236 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1238 struct rq *lowest_rq = NULL;
1239 int tries;
1240 int cpu;
1242 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1243 cpu = find_lowest_rq(task);
1245 if ((cpu == -1) || (cpu == rq->cpu))
1246 break;
1248 lowest_rq = cpu_rq(cpu);
1250 /* if the prio of this runqueue changed, try again */
1251 if (double_lock_balance(rq, lowest_rq)) {
1253 * We had to unlock the run queue. In
1254 * the mean time, task could have
1255 * migrated already or had its affinity changed.
1256 * Also make sure that it wasn't scheduled on its rq.
1258 if (unlikely(task_rq(task) != rq ||
1259 !cpumask_test_cpu(lowest_rq->cpu,
1260 &task->cpus_allowed) ||
1261 task_running(rq, task) ||
1262 !task->se.on_rq)) {
1264 raw_spin_unlock(&lowest_rq->lock);
1265 lowest_rq = NULL;
1266 break;
1270 /* If this rq is still suitable use it. */
1271 if (lowest_rq->rt.highest_prio.curr > task->prio)
1272 break;
1274 /* try again */
1275 double_unlock_balance(rq, lowest_rq);
1276 lowest_rq = NULL;
1279 return lowest_rq;
1282 static struct task_struct *pick_next_pushable_task(struct rq *rq)
1284 struct task_struct *p;
1286 if (!has_pushable_tasks(rq))
1287 return NULL;
1289 p = plist_first_entry(&rq->rt.pushable_tasks,
1290 struct task_struct, pushable_tasks);
1292 BUG_ON(rq->cpu != task_cpu(p));
1293 BUG_ON(task_current(rq, p));
1294 BUG_ON(p->rt.nr_cpus_allowed <= 1);
1296 BUG_ON(!p->se.on_rq);
1297 BUG_ON(!rt_task(p));
1299 return p;
1303 * If the current CPU has more than one RT task, see if the non
1304 * running task can migrate over to a CPU that is running a task
1305 * of lesser priority.
1307 static int push_rt_task(struct rq *rq)
1309 struct task_struct *next_task;
1310 struct rq *lowest_rq;
1312 if (!rq->rt.overloaded)
1313 return 0;
1315 next_task = pick_next_pushable_task(rq);
1316 if (!next_task)
1317 return 0;
1319 retry:
1320 if (unlikely(next_task == rq->curr)) {
1321 WARN_ON(1);
1322 return 0;
1326 * It's possible that the next_task slipped in of
1327 * higher priority than current. If that's the case
1328 * just reschedule current.
1330 if (unlikely(next_task->prio < rq->curr->prio)) {
1331 resched_task(rq->curr);
1332 return 0;
1335 /* We might release rq lock */
1336 get_task_struct(next_task);
1338 /* find_lock_lowest_rq locks the rq if found */
1339 lowest_rq = find_lock_lowest_rq(next_task, rq);
1340 if (!lowest_rq) {
1341 struct task_struct *task;
1343 * find lock_lowest_rq releases rq->lock
1344 * so it is possible that next_task has migrated.
1346 * We need to make sure that the task is still on the same
1347 * run-queue and is also still the next task eligible for
1348 * pushing.
1350 task = pick_next_pushable_task(rq);
1351 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1353 * If we get here, the task hasnt moved at all, but
1354 * it has failed to push. We will not try again,
1355 * since the other cpus will pull from us when they
1356 * are ready.
1358 dequeue_pushable_task(rq, next_task);
1359 goto out;
1362 if (!task)
1363 /* No more tasks, just exit */
1364 goto out;
1367 * Something has shifted, try again.
1369 put_task_struct(next_task);
1370 next_task = task;
1371 goto retry;
1374 deactivate_task(rq, next_task, 0);
1375 set_task_cpu(next_task, lowest_rq->cpu);
1376 activate_task(lowest_rq, next_task, 0);
1378 resched_task(lowest_rq->curr);
1380 double_unlock_balance(rq, lowest_rq);
1382 out:
1383 put_task_struct(next_task);
1385 return 1;
1388 static void push_rt_tasks(struct rq *rq)
1390 /* push_rt_task will return true if it moved an RT */
1391 while (push_rt_task(rq))
1395 static int pull_rt_task(struct rq *this_rq)
1397 int this_cpu = this_rq->cpu, ret = 0, cpu;
1398 struct task_struct *p;
1399 struct rq *src_rq;
1401 if (likely(!rt_overloaded(this_rq)))
1402 return 0;
1404 for_each_cpu(cpu, this_rq->rd->rto_mask) {
1405 if (this_cpu == cpu)
1406 continue;
1408 src_rq = cpu_rq(cpu);
1411 * Don't bother taking the src_rq->lock if the next highest
1412 * task is known to be lower-priority than our current task.
1413 * This may look racy, but if this value is about to go
1414 * logically higher, the src_rq will push this task away.
1415 * And if its going logically lower, we do not care
1417 if (src_rq->rt.highest_prio.next >=
1418 this_rq->rt.highest_prio.curr)
1419 continue;
1422 * We can potentially drop this_rq's lock in
1423 * double_lock_balance, and another CPU could
1424 * alter this_rq
1426 double_lock_balance(this_rq, src_rq);
1429 * Are there still pullable RT tasks?
1431 if (src_rq->rt.rt_nr_running <= 1)
1432 goto skip;
1434 p = pick_next_highest_task_rt(src_rq, this_cpu);
1437 * Do we have an RT task that preempts
1438 * the to-be-scheduled task?
1440 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
1441 WARN_ON(p == src_rq->curr);
1442 WARN_ON(!p->se.on_rq);
1445 * There's a chance that p is higher in priority
1446 * than what's currently running on its cpu.
1447 * This is just that p is wakeing up and hasn't
1448 * had a chance to schedule. We only pull
1449 * p if it is lower in priority than the
1450 * current task on the run queue
1452 if (p->prio < src_rq->curr->prio)
1453 goto skip;
1455 ret = 1;
1457 deactivate_task(src_rq, p, 0);
1458 set_task_cpu(p, this_cpu);
1459 activate_task(this_rq, p, 0);
1461 * We continue with the search, just in
1462 * case there's an even higher prio task
1463 * in another runqueue. (low likelyhood
1464 * but possible)
1467 skip:
1468 double_unlock_balance(this_rq, src_rq);
1471 return ret;
1474 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1476 /* Try to pull RT tasks here if we lower this rq's prio */
1477 if (unlikely(rt_task(prev)) && rq->rt.highest_prio.curr > prev->prio)
1478 pull_rt_task(rq);
1481 static void post_schedule_rt(struct rq *rq)
1483 push_rt_tasks(rq);
1487 * If we are not running and we are not going to reschedule soon, we should
1488 * try to push tasks away now
1490 static void task_woken_rt(struct rq *rq, struct task_struct *p)
1492 if (!task_running(rq, p) &&
1493 !test_tsk_need_resched(rq->curr) &&
1494 has_pushable_tasks(rq) &&
1495 p->rt.nr_cpus_allowed > 1 &&
1496 rt_task(rq->curr) &&
1497 (rq->curr->rt.nr_cpus_allowed < 2 ||
1498 rq->curr->prio < p->prio))
1499 push_rt_tasks(rq);
1502 static void set_cpus_allowed_rt(struct task_struct *p,
1503 const struct cpumask *new_mask)
1505 int weight = cpumask_weight(new_mask);
1507 BUG_ON(!rt_task(p));
1510 * Update the migration status of the RQ if we have an RT task
1511 * which is running AND changing its weight value.
1513 if (p->se.on_rq && (weight != p->rt.nr_cpus_allowed)) {
1514 struct rq *rq = task_rq(p);
1516 if (!task_current(rq, p)) {
1518 * Make sure we dequeue this task from the pushable list
1519 * before going further. It will either remain off of
1520 * the list because we are no longer pushable, or it
1521 * will be requeued.
1523 if (p->rt.nr_cpus_allowed > 1)
1524 dequeue_pushable_task(rq, p);
1527 * Requeue if our weight is changing and still > 1
1529 if (weight > 1)
1530 enqueue_pushable_task(rq, p);
1534 if ((p->rt.nr_cpus_allowed <= 1) && (weight > 1)) {
1535 rq->rt.rt_nr_migratory++;
1536 } else if ((p->rt.nr_cpus_allowed > 1) && (weight <= 1)) {
1537 BUG_ON(!rq->rt.rt_nr_migratory);
1538 rq->rt.rt_nr_migratory--;
1541 update_rt_migration(&rq->rt);
1544 cpumask_copy(&p->cpus_allowed, new_mask);
1545 p->rt.nr_cpus_allowed = weight;
1548 /* Assumes rq->lock is held */
1549 static void rq_online_rt(struct rq *rq)
1551 if (rq->rt.overloaded)
1552 rt_set_overload(rq);
1554 __enable_runtime(rq);
1556 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1559 /* Assumes rq->lock is held */
1560 static void rq_offline_rt(struct rq *rq)
1562 if (rq->rt.overloaded)
1563 rt_clear_overload(rq);
1565 __disable_runtime(rq);
1567 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1571 * When switch from the rt queue, we bring ourselves to a position
1572 * that we might want to pull RT tasks from other runqueues.
1574 static void switched_from_rt(struct rq *rq, struct task_struct *p,
1575 int running)
1578 * If there are other RT tasks then we will reschedule
1579 * and the scheduling of the other RT tasks will handle
1580 * the balancing. But if we are the last RT task
1581 * we may need to handle the pulling of RT tasks
1582 * now.
1584 if (!rq->rt.rt_nr_running)
1585 pull_rt_task(rq);
1588 static inline void init_sched_rt_class(void)
1590 unsigned int i;
1592 for_each_possible_cpu(i)
1593 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
1594 GFP_KERNEL, cpu_to_node(i));
1596 #endif /* CONFIG_SMP */
1599 * When switching a task to RT, we may overload the runqueue
1600 * with RT tasks. In this case we try to push them off to
1601 * other runqueues.
1603 static void switched_to_rt(struct rq *rq, struct task_struct *p,
1604 int running)
1606 int check_resched = 1;
1609 * If we are already running, then there's nothing
1610 * that needs to be done. But if we are not running
1611 * we may need to preempt the current running task.
1612 * If that current running task is also an RT task
1613 * then see if we can move to another run queue.
1615 if (!running) {
1616 #ifdef CONFIG_SMP
1617 if (rq->rt.overloaded && push_rt_task(rq) &&
1618 /* Don't resched if we changed runqueues */
1619 rq != task_rq(p))
1620 check_resched = 0;
1621 #endif /* CONFIG_SMP */
1622 if (check_resched && p->prio < rq->curr->prio)
1623 resched_task(rq->curr);
1628 * Priority of the task has changed. This may cause
1629 * us to initiate a push or pull.
1631 static void prio_changed_rt(struct rq *rq, struct task_struct *p,
1632 int oldprio, int running)
1634 if (running) {
1635 #ifdef CONFIG_SMP
1637 * If our priority decreases while running, we
1638 * may need to pull tasks to this runqueue.
1640 if (oldprio < p->prio)
1641 pull_rt_task(rq);
1643 * If there's a higher priority task waiting to run
1644 * then reschedule. Note, the above pull_rt_task
1645 * can release the rq lock and p could migrate.
1646 * Only reschedule if p is still on the same runqueue.
1648 if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
1649 resched_task(p);
1650 #else
1651 /* For UP simply resched on drop of prio */
1652 if (oldprio < p->prio)
1653 resched_task(p);
1654 #endif /* CONFIG_SMP */
1655 } else {
1657 * This task is not running, but if it is
1658 * greater than the current running task
1659 * then reschedule.
1661 if (p->prio < rq->curr->prio)
1662 resched_task(rq->curr);
1666 static void watchdog(struct rq *rq, struct task_struct *p)
1668 unsigned long soft, hard;
1670 /* max may change after cur was read, this will be fixed next tick */
1671 soft = task_rlimit(p, RLIMIT_RTTIME);
1672 hard = task_rlimit_max(p, RLIMIT_RTTIME);
1674 if (soft != RLIM_INFINITY) {
1675 unsigned long next;
1677 p->rt.timeout++;
1678 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1679 if (p->rt.timeout > next)
1680 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
1684 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1686 update_curr_rt(rq);
1688 watchdog(rq, p);
1691 * RR tasks need a special form of timeslice management.
1692 * FIFO tasks have no timeslices.
1694 if (p->policy != SCHED_RR)
1695 return;
1697 if (--p->rt.time_slice)
1698 return;
1700 p->rt.time_slice = DEF_TIMESLICE;
1703 * Requeue to the end of queue if we are not the only element
1704 * on the queue:
1706 if (p->rt.run_list.prev != p->rt.run_list.next) {
1707 requeue_task_rt(rq, p, 0);
1708 set_tsk_need_resched(p);
1712 static void set_curr_task_rt(struct rq *rq)
1714 struct task_struct *p = rq->curr;
1716 p->se.exec_start = rq->clock_task;
1718 /* The running task is never eligible for pushing */
1719 dequeue_pushable_task(rq, p);
1722 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
1725 * Time slice is 0 for SCHED_FIFO tasks
1727 if (task->policy == SCHED_RR)
1728 return DEF_TIMESLICE;
1729 else
1730 return 0;
1733 static const struct sched_class rt_sched_class = {
1734 .next = &fair_sched_class,
1735 .enqueue_task = enqueue_task_rt,
1736 .dequeue_task = dequeue_task_rt,
1737 .yield_task = yield_task_rt,
1739 .check_preempt_curr = check_preempt_curr_rt,
1741 .pick_next_task = pick_next_task_rt,
1742 .put_prev_task = put_prev_task_rt,
1744 #ifdef CONFIG_SMP
1745 .select_task_rq = select_task_rq_rt,
1747 .set_cpus_allowed = set_cpus_allowed_rt,
1748 .rq_online = rq_online_rt,
1749 .rq_offline = rq_offline_rt,
1750 .pre_schedule = pre_schedule_rt,
1751 .post_schedule = post_schedule_rt,
1752 .task_woken = task_woken_rt,
1753 .switched_from = switched_from_rt,
1754 #endif
1756 .set_curr_task = set_curr_task_rt,
1757 .task_tick = task_tick_rt,
1759 .get_rr_interval = get_rr_interval_rt,
1761 .prio_changed = prio_changed_rt,
1762 .switched_to = switched_to_rt,
1765 #ifdef CONFIG_SCHED_DEBUG
1766 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
1768 static void print_rt_stats(struct seq_file *m, int cpu)
1770 struct rt_rq *rt_rq;
1772 rcu_read_lock();
1773 for_each_leaf_rt_rq(rt_rq, cpu_rq(cpu))
1774 print_rt_rq(m, cpu, rt_rq);
1775 rcu_read_unlock();
1777 #endif /* CONFIG_SCHED_DEBUG */