iwlwifi: increase scan timeout
[linux-2.6.git] / kernel / sched / rt.c
blobc5565c3c515fd2d15dc5ed95f59a970fca087815
1 /*
2 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
3 * policies)
4 */
6 #include "sched.h"
8 #include <linux/slab.h>
10 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
12 struct rt_bandwidth def_rt_bandwidth;
14 static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
16 struct rt_bandwidth *rt_b =
17 container_of(timer, struct rt_bandwidth, rt_period_timer);
18 ktime_t now;
19 int overrun;
20 int idle = 0;
22 for (;;) {
23 now = hrtimer_cb_get_time(timer);
24 overrun = hrtimer_forward(timer, now, rt_b->rt_period);
26 if (!overrun)
27 break;
29 idle = do_sched_rt_period_timer(rt_b, overrun);
32 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
35 void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
37 rt_b->rt_period = ns_to_ktime(period);
38 rt_b->rt_runtime = runtime;
40 raw_spin_lock_init(&rt_b->rt_runtime_lock);
42 hrtimer_init(&rt_b->rt_period_timer,
43 CLOCK_MONOTONIC, HRTIMER_MODE_REL);
44 rt_b->rt_period_timer.function = sched_rt_period_timer;
47 static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
49 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
50 return;
52 if (hrtimer_active(&rt_b->rt_period_timer))
53 return;
55 raw_spin_lock(&rt_b->rt_runtime_lock);
56 start_bandwidth_timer(&rt_b->rt_period_timer, rt_b->rt_period);
57 raw_spin_unlock(&rt_b->rt_runtime_lock);
60 void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
62 struct rt_prio_array *array;
63 int i;
65 array = &rt_rq->active;
66 for (i = 0; i < MAX_RT_PRIO; i++) {
67 INIT_LIST_HEAD(array->queue + i);
68 __clear_bit(i, array->bitmap);
70 /* delimiter for bitsearch: */
71 __set_bit(MAX_RT_PRIO, array->bitmap);
73 #if defined CONFIG_SMP
74 rt_rq->highest_prio.curr = MAX_RT_PRIO;
75 rt_rq->highest_prio.next = MAX_RT_PRIO;
76 rt_rq->rt_nr_migratory = 0;
77 rt_rq->overloaded = 0;
78 plist_head_init(&rt_rq->pushable_tasks);
79 #endif
81 rt_rq->rt_time = 0;
82 rt_rq->rt_throttled = 0;
83 rt_rq->rt_runtime = 0;
84 raw_spin_lock_init(&rt_rq->rt_runtime_lock);
87 #ifdef CONFIG_RT_GROUP_SCHED
88 static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
90 hrtimer_cancel(&rt_b->rt_period_timer);
93 #define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
95 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
97 #ifdef CONFIG_SCHED_DEBUG
98 WARN_ON_ONCE(!rt_entity_is_task(rt_se));
99 #endif
100 return container_of(rt_se, struct task_struct, rt);
103 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
105 return rt_rq->rq;
108 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
110 return rt_se->rt_rq;
113 void free_rt_sched_group(struct task_group *tg)
115 int i;
117 if (tg->rt_se)
118 destroy_rt_bandwidth(&tg->rt_bandwidth);
120 for_each_possible_cpu(i) {
121 if (tg->rt_rq)
122 kfree(tg->rt_rq[i]);
123 if (tg->rt_se)
124 kfree(tg->rt_se[i]);
127 kfree(tg->rt_rq);
128 kfree(tg->rt_se);
131 void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
132 struct sched_rt_entity *rt_se, int cpu,
133 struct sched_rt_entity *parent)
135 struct rq *rq = cpu_rq(cpu);
137 rt_rq->highest_prio.curr = MAX_RT_PRIO;
138 rt_rq->rt_nr_boosted = 0;
139 rt_rq->rq = rq;
140 rt_rq->tg = tg;
142 tg->rt_rq[cpu] = rt_rq;
143 tg->rt_se[cpu] = rt_se;
145 if (!rt_se)
146 return;
148 if (!parent)
149 rt_se->rt_rq = &rq->rt;
150 else
151 rt_se->rt_rq = parent->my_q;
153 rt_se->my_q = rt_rq;
154 rt_se->parent = parent;
155 INIT_LIST_HEAD(&rt_se->run_list);
158 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
160 struct rt_rq *rt_rq;
161 struct sched_rt_entity *rt_se;
162 int i;
164 tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
165 if (!tg->rt_rq)
166 goto err;
167 tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
168 if (!tg->rt_se)
169 goto err;
171 init_rt_bandwidth(&tg->rt_bandwidth,
172 ktime_to_ns(def_rt_bandwidth.rt_period), 0);
174 for_each_possible_cpu(i) {
175 rt_rq = kzalloc_node(sizeof(struct rt_rq),
176 GFP_KERNEL, cpu_to_node(i));
177 if (!rt_rq)
178 goto err;
180 rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
181 GFP_KERNEL, cpu_to_node(i));
182 if (!rt_se)
183 goto err_free_rq;
185 init_rt_rq(rt_rq, cpu_rq(i));
186 rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
187 init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
190 return 1;
192 err_free_rq:
193 kfree(rt_rq);
194 err:
195 return 0;
198 #else /* CONFIG_RT_GROUP_SCHED */
200 #define rt_entity_is_task(rt_se) (1)
202 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
204 return container_of(rt_se, struct task_struct, rt);
207 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
209 return container_of(rt_rq, struct rq, rt);
212 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
214 struct task_struct *p = rt_task_of(rt_se);
215 struct rq *rq = task_rq(p);
217 return &rq->rt;
220 void free_rt_sched_group(struct task_group *tg) { }
222 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
224 return 1;
226 #endif /* CONFIG_RT_GROUP_SCHED */
228 #ifdef CONFIG_SMP
230 static inline int rt_overloaded(struct rq *rq)
232 return atomic_read(&rq->rd->rto_count);
235 static inline void rt_set_overload(struct rq *rq)
237 if (!rq->online)
238 return;
240 cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
242 * Make sure the mask is visible before we set
243 * the overload count. That is checked to determine
244 * if we should look at the mask. It would be a shame
245 * if we looked at the mask, but the mask was not
246 * updated yet.
248 wmb();
249 atomic_inc(&rq->rd->rto_count);
252 static inline void rt_clear_overload(struct rq *rq)
254 if (!rq->online)
255 return;
257 /* the order here really doesn't matter */
258 atomic_dec(&rq->rd->rto_count);
259 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
262 static void update_rt_migration(struct rt_rq *rt_rq)
264 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
265 if (!rt_rq->overloaded) {
266 rt_set_overload(rq_of_rt_rq(rt_rq));
267 rt_rq->overloaded = 1;
269 } else if (rt_rq->overloaded) {
270 rt_clear_overload(rq_of_rt_rq(rt_rq));
271 rt_rq->overloaded = 0;
275 static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
277 if (!rt_entity_is_task(rt_se))
278 return;
280 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
282 rt_rq->rt_nr_total++;
283 if (rt_se->nr_cpus_allowed > 1)
284 rt_rq->rt_nr_migratory++;
286 update_rt_migration(rt_rq);
289 static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
291 if (!rt_entity_is_task(rt_se))
292 return;
294 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
296 rt_rq->rt_nr_total--;
297 if (rt_se->nr_cpus_allowed > 1)
298 rt_rq->rt_nr_migratory--;
300 update_rt_migration(rt_rq);
303 static inline int has_pushable_tasks(struct rq *rq)
305 return !plist_head_empty(&rq->rt.pushable_tasks);
308 static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
310 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
311 plist_node_init(&p->pushable_tasks, p->prio);
312 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
314 /* Update the highest prio pushable task */
315 if (p->prio < rq->rt.highest_prio.next)
316 rq->rt.highest_prio.next = p->prio;
319 static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
321 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
323 /* Update the new highest prio pushable task */
324 if (has_pushable_tasks(rq)) {
325 p = plist_first_entry(&rq->rt.pushable_tasks,
326 struct task_struct, pushable_tasks);
327 rq->rt.highest_prio.next = p->prio;
328 } else
329 rq->rt.highest_prio.next = MAX_RT_PRIO;
332 #else
334 static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
338 static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
342 static inline
343 void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
347 static inline
348 void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
352 #endif /* CONFIG_SMP */
354 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
356 return !list_empty(&rt_se->run_list);
359 #ifdef CONFIG_RT_GROUP_SCHED
361 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
363 if (!rt_rq->tg)
364 return RUNTIME_INF;
366 return rt_rq->rt_runtime;
369 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
371 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
374 typedef struct task_group *rt_rq_iter_t;
376 static inline struct task_group *next_task_group(struct task_group *tg)
378 do {
379 tg = list_entry_rcu(tg->list.next,
380 typeof(struct task_group), list);
381 } while (&tg->list != &task_groups && task_group_is_autogroup(tg));
383 if (&tg->list == &task_groups)
384 tg = NULL;
386 return tg;
389 #define for_each_rt_rq(rt_rq, iter, rq) \
390 for (iter = container_of(&task_groups, typeof(*iter), list); \
391 (iter = next_task_group(iter)) && \
392 (rt_rq = iter->rt_rq[cpu_of(rq)]);)
394 static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
396 list_add_rcu(&rt_rq->leaf_rt_rq_list,
397 &rq_of_rt_rq(rt_rq)->leaf_rt_rq_list);
400 static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
402 list_del_rcu(&rt_rq->leaf_rt_rq_list);
405 #define for_each_leaf_rt_rq(rt_rq, rq) \
406 list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
408 #define for_each_sched_rt_entity(rt_se) \
409 for (; rt_se; rt_se = rt_se->parent)
411 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
413 return rt_se->my_q;
416 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
417 static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
419 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
421 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
422 struct sched_rt_entity *rt_se;
424 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
426 rt_se = rt_rq->tg->rt_se[cpu];
428 if (rt_rq->rt_nr_running) {
429 if (rt_se && !on_rt_rq(rt_se))
430 enqueue_rt_entity(rt_se, false);
431 if (rt_rq->highest_prio.curr < curr->prio)
432 resched_task(curr);
436 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
438 struct sched_rt_entity *rt_se;
439 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
441 rt_se = rt_rq->tg->rt_se[cpu];
443 if (rt_se && on_rt_rq(rt_se))
444 dequeue_rt_entity(rt_se);
447 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
449 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
452 static int rt_se_boosted(struct sched_rt_entity *rt_se)
454 struct rt_rq *rt_rq = group_rt_rq(rt_se);
455 struct task_struct *p;
457 if (rt_rq)
458 return !!rt_rq->rt_nr_boosted;
460 p = rt_task_of(rt_se);
461 return p->prio != p->normal_prio;
464 #ifdef CONFIG_SMP
465 static inline const struct cpumask *sched_rt_period_mask(void)
467 return cpu_rq(smp_processor_id())->rd->span;
469 #else
470 static inline const struct cpumask *sched_rt_period_mask(void)
472 return cpu_online_mask;
474 #endif
476 static inline
477 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
479 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
482 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
484 return &rt_rq->tg->rt_bandwidth;
487 #else /* !CONFIG_RT_GROUP_SCHED */
489 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
491 return rt_rq->rt_runtime;
494 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
496 return ktime_to_ns(def_rt_bandwidth.rt_period);
499 typedef struct rt_rq *rt_rq_iter_t;
501 #define for_each_rt_rq(rt_rq, iter, rq) \
502 for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
504 static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
508 static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
512 #define for_each_leaf_rt_rq(rt_rq, rq) \
513 for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
515 #define for_each_sched_rt_entity(rt_se) \
516 for (; rt_se; rt_se = NULL)
518 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
520 return NULL;
523 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
525 if (rt_rq->rt_nr_running)
526 resched_task(rq_of_rt_rq(rt_rq)->curr);
529 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
533 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
535 return rt_rq->rt_throttled;
538 static inline const struct cpumask *sched_rt_period_mask(void)
540 return cpu_online_mask;
543 static inline
544 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
546 return &cpu_rq(cpu)->rt;
549 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
551 return &def_rt_bandwidth;
554 #endif /* CONFIG_RT_GROUP_SCHED */
556 #ifdef CONFIG_SMP
558 * We ran out of runtime, see if we can borrow some from our neighbours.
560 static int do_balance_runtime(struct rt_rq *rt_rq)
562 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
563 struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
564 int i, weight, more = 0;
565 u64 rt_period;
567 weight = cpumask_weight(rd->span);
569 raw_spin_lock(&rt_b->rt_runtime_lock);
570 rt_period = ktime_to_ns(rt_b->rt_period);
571 for_each_cpu(i, rd->span) {
572 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
573 s64 diff;
575 if (iter == rt_rq)
576 continue;
578 raw_spin_lock(&iter->rt_runtime_lock);
580 * Either all rqs have inf runtime and there's nothing to steal
581 * or __disable_runtime() below sets a specific rq to inf to
582 * indicate its been disabled and disalow stealing.
584 if (iter->rt_runtime == RUNTIME_INF)
585 goto next;
588 * From runqueues with spare time, take 1/n part of their
589 * spare time, but no more than our period.
591 diff = iter->rt_runtime - iter->rt_time;
592 if (diff > 0) {
593 diff = div_u64((u64)diff, weight);
594 if (rt_rq->rt_runtime + diff > rt_period)
595 diff = rt_period - rt_rq->rt_runtime;
596 iter->rt_runtime -= diff;
597 rt_rq->rt_runtime += diff;
598 more = 1;
599 if (rt_rq->rt_runtime == rt_period) {
600 raw_spin_unlock(&iter->rt_runtime_lock);
601 break;
604 next:
605 raw_spin_unlock(&iter->rt_runtime_lock);
607 raw_spin_unlock(&rt_b->rt_runtime_lock);
609 return more;
613 * Ensure this RQ takes back all the runtime it lend to its neighbours.
615 static void __disable_runtime(struct rq *rq)
617 struct root_domain *rd = rq->rd;
618 rt_rq_iter_t iter;
619 struct rt_rq *rt_rq;
621 if (unlikely(!scheduler_running))
622 return;
624 for_each_rt_rq(rt_rq, iter, rq) {
625 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
626 s64 want;
627 int i;
629 raw_spin_lock(&rt_b->rt_runtime_lock);
630 raw_spin_lock(&rt_rq->rt_runtime_lock);
632 * Either we're all inf and nobody needs to borrow, or we're
633 * already disabled and thus have nothing to do, or we have
634 * exactly the right amount of runtime to take out.
636 if (rt_rq->rt_runtime == RUNTIME_INF ||
637 rt_rq->rt_runtime == rt_b->rt_runtime)
638 goto balanced;
639 raw_spin_unlock(&rt_rq->rt_runtime_lock);
642 * Calculate the difference between what we started out with
643 * and what we current have, that's the amount of runtime
644 * we lend and now have to reclaim.
646 want = rt_b->rt_runtime - rt_rq->rt_runtime;
649 * Greedy reclaim, take back as much as we can.
651 for_each_cpu(i, rd->span) {
652 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
653 s64 diff;
656 * Can't reclaim from ourselves or disabled runqueues.
658 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
659 continue;
661 raw_spin_lock(&iter->rt_runtime_lock);
662 if (want > 0) {
663 diff = min_t(s64, iter->rt_runtime, want);
664 iter->rt_runtime -= diff;
665 want -= diff;
666 } else {
667 iter->rt_runtime -= want;
668 want -= want;
670 raw_spin_unlock(&iter->rt_runtime_lock);
672 if (!want)
673 break;
676 raw_spin_lock(&rt_rq->rt_runtime_lock);
678 * We cannot be left wanting - that would mean some runtime
679 * leaked out of the system.
681 BUG_ON(want);
682 balanced:
684 * Disable all the borrow logic by pretending we have inf
685 * runtime - in which case borrowing doesn't make sense.
687 rt_rq->rt_runtime = RUNTIME_INF;
688 raw_spin_unlock(&rt_rq->rt_runtime_lock);
689 raw_spin_unlock(&rt_b->rt_runtime_lock);
693 static void disable_runtime(struct rq *rq)
695 unsigned long flags;
697 raw_spin_lock_irqsave(&rq->lock, flags);
698 __disable_runtime(rq);
699 raw_spin_unlock_irqrestore(&rq->lock, flags);
702 static void __enable_runtime(struct rq *rq)
704 rt_rq_iter_t iter;
705 struct rt_rq *rt_rq;
707 if (unlikely(!scheduler_running))
708 return;
711 * Reset each runqueue's bandwidth settings
713 for_each_rt_rq(rt_rq, iter, rq) {
714 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
716 raw_spin_lock(&rt_b->rt_runtime_lock);
717 raw_spin_lock(&rt_rq->rt_runtime_lock);
718 rt_rq->rt_runtime = rt_b->rt_runtime;
719 rt_rq->rt_time = 0;
720 rt_rq->rt_throttled = 0;
721 raw_spin_unlock(&rt_rq->rt_runtime_lock);
722 raw_spin_unlock(&rt_b->rt_runtime_lock);
726 static void enable_runtime(struct rq *rq)
728 unsigned long flags;
730 raw_spin_lock_irqsave(&rq->lock, flags);
731 __enable_runtime(rq);
732 raw_spin_unlock_irqrestore(&rq->lock, flags);
735 int update_runtime(struct notifier_block *nfb, unsigned long action, void *hcpu)
737 int cpu = (int)(long)hcpu;
739 switch (action) {
740 case CPU_DOWN_PREPARE:
741 case CPU_DOWN_PREPARE_FROZEN:
742 disable_runtime(cpu_rq(cpu));
743 return NOTIFY_OK;
745 case CPU_DOWN_FAILED:
746 case CPU_DOWN_FAILED_FROZEN:
747 case CPU_ONLINE:
748 case CPU_ONLINE_FROZEN:
749 enable_runtime(cpu_rq(cpu));
750 return NOTIFY_OK;
752 default:
753 return NOTIFY_DONE;
757 static int balance_runtime(struct rt_rq *rt_rq)
759 int more = 0;
761 if (!sched_feat(RT_RUNTIME_SHARE))
762 return more;
764 if (rt_rq->rt_time > rt_rq->rt_runtime) {
765 raw_spin_unlock(&rt_rq->rt_runtime_lock);
766 more = do_balance_runtime(rt_rq);
767 raw_spin_lock(&rt_rq->rt_runtime_lock);
770 return more;
772 #else /* !CONFIG_SMP */
773 static inline int balance_runtime(struct rt_rq *rt_rq)
775 return 0;
777 #endif /* CONFIG_SMP */
779 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
781 int i, idle = 1, throttled = 0;
782 const struct cpumask *span;
784 span = sched_rt_period_mask();
785 for_each_cpu(i, span) {
786 int enqueue = 0;
787 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
788 struct rq *rq = rq_of_rt_rq(rt_rq);
790 raw_spin_lock(&rq->lock);
791 if (rt_rq->rt_time) {
792 u64 runtime;
794 raw_spin_lock(&rt_rq->rt_runtime_lock);
795 if (rt_rq->rt_throttled)
796 balance_runtime(rt_rq);
797 runtime = rt_rq->rt_runtime;
798 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
799 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
800 rt_rq->rt_throttled = 0;
801 enqueue = 1;
804 * Force a clock update if the CPU was idle,
805 * lest wakeup -> unthrottle time accumulate.
807 if (rt_rq->rt_nr_running && rq->curr == rq->idle)
808 rq->skip_clock_update = -1;
810 if (rt_rq->rt_time || rt_rq->rt_nr_running)
811 idle = 0;
812 raw_spin_unlock(&rt_rq->rt_runtime_lock);
813 } else if (rt_rq->rt_nr_running) {
814 idle = 0;
815 if (!rt_rq_throttled(rt_rq))
816 enqueue = 1;
818 if (rt_rq->rt_throttled)
819 throttled = 1;
821 if (enqueue)
822 sched_rt_rq_enqueue(rt_rq);
823 raw_spin_unlock(&rq->lock);
826 if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
827 return 1;
829 return idle;
832 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
834 #ifdef CONFIG_RT_GROUP_SCHED
835 struct rt_rq *rt_rq = group_rt_rq(rt_se);
837 if (rt_rq)
838 return rt_rq->highest_prio.curr;
839 #endif
841 return rt_task_of(rt_se)->prio;
844 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
846 u64 runtime = sched_rt_runtime(rt_rq);
848 if (rt_rq->rt_throttled)
849 return rt_rq_throttled(rt_rq);
851 if (runtime >= sched_rt_period(rt_rq))
852 return 0;
854 balance_runtime(rt_rq);
855 runtime = sched_rt_runtime(rt_rq);
856 if (runtime == RUNTIME_INF)
857 return 0;
859 if (rt_rq->rt_time > runtime) {
860 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
863 * Don't actually throttle groups that have no runtime assigned
864 * but accrue some time due to boosting.
866 if (likely(rt_b->rt_runtime)) {
867 static bool once = false;
869 rt_rq->rt_throttled = 1;
871 if (!once) {
872 once = true;
873 printk_sched("sched: RT throttling activated\n");
875 } else {
877 * In case we did anyway, make it go away,
878 * replenishment is a joke, since it will replenish us
879 * with exactly 0 ns.
881 rt_rq->rt_time = 0;
884 if (rt_rq_throttled(rt_rq)) {
885 sched_rt_rq_dequeue(rt_rq);
886 return 1;
890 return 0;
894 * Update the current task's runtime statistics. Skip current tasks that
895 * are not in our scheduling class.
897 static void update_curr_rt(struct rq *rq)
899 struct task_struct *curr = rq->curr;
900 struct sched_rt_entity *rt_se = &curr->rt;
901 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
902 u64 delta_exec;
904 if (curr->sched_class != &rt_sched_class)
905 return;
907 delta_exec = rq->clock_task - curr->se.exec_start;
908 if (unlikely((s64)delta_exec < 0))
909 delta_exec = 0;
911 schedstat_set(curr->se.statistics.exec_max,
912 max(curr->se.statistics.exec_max, delta_exec));
914 curr->se.sum_exec_runtime += delta_exec;
915 account_group_exec_runtime(curr, delta_exec);
917 curr->se.exec_start = rq->clock_task;
918 cpuacct_charge(curr, delta_exec);
920 sched_rt_avg_update(rq, delta_exec);
922 if (!rt_bandwidth_enabled())
923 return;
925 for_each_sched_rt_entity(rt_se) {
926 rt_rq = rt_rq_of_se(rt_se);
928 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
929 raw_spin_lock(&rt_rq->rt_runtime_lock);
930 rt_rq->rt_time += delta_exec;
931 if (sched_rt_runtime_exceeded(rt_rq))
932 resched_task(curr);
933 raw_spin_unlock(&rt_rq->rt_runtime_lock);
938 #if defined CONFIG_SMP
940 static void
941 inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
943 struct rq *rq = rq_of_rt_rq(rt_rq);
945 if (rq->online && prio < prev_prio)
946 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
949 static void
950 dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
952 struct rq *rq = rq_of_rt_rq(rt_rq);
954 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
955 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
958 #else /* CONFIG_SMP */
960 static inline
961 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
962 static inline
963 void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
965 #endif /* CONFIG_SMP */
967 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
968 static void
969 inc_rt_prio(struct rt_rq *rt_rq, int prio)
971 int prev_prio = rt_rq->highest_prio.curr;
973 if (prio < prev_prio)
974 rt_rq->highest_prio.curr = prio;
976 inc_rt_prio_smp(rt_rq, prio, prev_prio);
979 static void
980 dec_rt_prio(struct rt_rq *rt_rq, int prio)
982 int prev_prio = rt_rq->highest_prio.curr;
984 if (rt_rq->rt_nr_running) {
986 WARN_ON(prio < prev_prio);
989 * This may have been our highest task, and therefore
990 * we may have some recomputation to do
992 if (prio == prev_prio) {
993 struct rt_prio_array *array = &rt_rq->active;
995 rt_rq->highest_prio.curr =
996 sched_find_first_bit(array->bitmap);
999 } else
1000 rt_rq->highest_prio.curr = MAX_RT_PRIO;
1002 dec_rt_prio_smp(rt_rq, prio, prev_prio);
1005 #else
1007 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
1008 static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
1010 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
1012 #ifdef CONFIG_RT_GROUP_SCHED
1014 static void
1015 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1017 if (rt_se_boosted(rt_se))
1018 rt_rq->rt_nr_boosted++;
1020 if (rt_rq->tg)
1021 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
1024 static void
1025 dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1027 if (rt_se_boosted(rt_se))
1028 rt_rq->rt_nr_boosted--;
1030 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
1033 #else /* CONFIG_RT_GROUP_SCHED */
1035 static void
1036 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1038 start_rt_bandwidth(&def_rt_bandwidth);
1041 static inline
1042 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1044 #endif /* CONFIG_RT_GROUP_SCHED */
1046 static inline
1047 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1049 int prio = rt_se_prio(rt_se);
1051 WARN_ON(!rt_prio(prio));
1052 rt_rq->rt_nr_running++;
1054 inc_rt_prio(rt_rq, prio);
1055 inc_rt_migration(rt_se, rt_rq);
1056 inc_rt_group(rt_se, rt_rq);
1059 static inline
1060 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1062 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
1063 WARN_ON(!rt_rq->rt_nr_running);
1064 rt_rq->rt_nr_running--;
1066 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
1067 dec_rt_migration(rt_se, rt_rq);
1068 dec_rt_group(rt_se, rt_rq);
1071 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1073 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1074 struct rt_prio_array *array = &rt_rq->active;
1075 struct rt_rq *group_rq = group_rt_rq(rt_se);
1076 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1079 * Don't enqueue the group if its throttled, or when empty.
1080 * The latter is a consequence of the former when a child group
1081 * get throttled and the current group doesn't have any other
1082 * active members.
1084 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
1085 return;
1087 if (!rt_rq->rt_nr_running)
1088 list_add_leaf_rt_rq(rt_rq);
1090 if (head)
1091 list_add(&rt_se->run_list, queue);
1092 else
1093 list_add_tail(&rt_se->run_list, queue);
1094 __set_bit(rt_se_prio(rt_se), array->bitmap);
1096 inc_rt_tasks(rt_se, rt_rq);
1099 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
1101 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1102 struct rt_prio_array *array = &rt_rq->active;
1104 list_del_init(&rt_se->run_list);
1105 if (list_empty(array->queue + rt_se_prio(rt_se)))
1106 __clear_bit(rt_se_prio(rt_se), array->bitmap);
1108 dec_rt_tasks(rt_se, rt_rq);
1109 if (!rt_rq->rt_nr_running)
1110 list_del_leaf_rt_rq(rt_rq);
1114 * Because the prio of an upper entry depends on the lower
1115 * entries, we must remove entries top - down.
1117 static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
1119 struct sched_rt_entity *back = NULL;
1121 for_each_sched_rt_entity(rt_se) {
1122 rt_se->back = back;
1123 back = rt_se;
1126 for (rt_se = back; rt_se; rt_se = rt_se->back) {
1127 if (on_rt_rq(rt_se))
1128 __dequeue_rt_entity(rt_se);
1132 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1134 dequeue_rt_stack(rt_se);
1135 for_each_sched_rt_entity(rt_se)
1136 __enqueue_rt_entity(rt_se, head);
1139 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
1141 dequeue_rt_stack(rt_se);
1143 for_each_sched_rt_entity(rt_se) {
1144 struct rt_rq *rt_rq = group_rt_rq(rt_se);
1146 if (rt_rq && rt_rq->rt_nr_running)
1147 __enqueue_rt_entity(rt_se, false);
1152 * Adding/removing a task to/from a priority array:
1154 static void
1155 enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1157 struct sched_rt_entity *rt_se = &p->rt;
1159 if (flags & ENQUEUE_WAKEUP)
1160 rt_se->timeout = 0;
1162 enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
1164 if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
1165 enqueue_pushable_task(rq, p);
1167 inc_nr_running(rq);
1170 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1172 struct sched_rt_entity *rt_se = &p->rt;
1174 update_curr_rt(rq);
1175 dequeue_rt_entity(rt_se);
1177 dequeue_pushable_task(rq, p);
1179 dec_nr_running(rq);
1183 * Put task to the head or the end of the run list without the overhead of
1184 * dequeue followed by enqueue.
1186 static void
1187 requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
1189 if (on_rt_rq(rt_se)) {
1190 struct rt_prio_array *array = &rt_rq->active;
1191 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1193 if (head)
1194 list_move(&rt_se->run_list, queue);
1195 else
1196 list_move_tail(&rt_se->run_list, queue);
1200 static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
1202 struct sched_rt_entity *rt_se = &p->rt;
1203 struct rt_rq *rt_rq;
1205 for_each_sched_rt_entity(rt_se) {
1206 rt_rq = rt_rq_of_se(rt_se);
1207 requeue_rt_entity(rt_rq, rt_se, head);
1211 static void yield_task_rt(struct rq *rq)
1213 requeue_task_rt(rq, rq->curr, 0);
1216 #ifdef CONFIG_SMP
1217 static int find_lowest_rq(struct task_struct *task);
1219 static int
1220 select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
1222 struct task_struct *curr;
1223 struct rq *rq;
1224 int cpu;
1226 cpu = task_cpu(p);
1228 if (p->rt.nr_cpus_allowed == 1)
1229 goto out;
1231 /* For anything but wake ups, just return the task_cpu */
1232 if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
1233 goto out;
1235 rq = cpu_rq(cpu);
1237 rcu_read_lock();
1238 curr = ACCESS_ONCE(rq->curr); /* unlocked access */
1241 * If the current task on @p's runqueue is an RT task, then
1242 * try to see if we can wake this RT task up on another
1243 * runqueue. Otherwise simply start this RT task
1244 * on its current runqueue.
1246 * We want to avoid overloading runqueues. If the woken
1247 * task is a higher priority, then it will stay on this CPU
1248 * and the lower prio task should be moved to another CPU.
1249 * Even though this will probably make the lower prio task
1250 * lose its cache, we do not want to bounce a higher task
1251 * around just because it gave up its CPU, perhaps for a
1252 * lock?
1254 * For equal prio tasks, we just let the scheduler sort it out.
1256 * Otherwise, just let it ride on the affined RQ and the
1257 * post-schedule router will push the preempted task away
1259 * This test is optimistic, if we get it wrong the load-balancer
1260 * will have to sort it out.
1262 if (curr && unlikely(rt_task(curr)) &&
1263 (curr->rt.nr_cpus_allowed < 2 ||
1264 curr->prio <= p->prio) &&
1265 (p->rt.nr_cpus_allowed > 1)) {
1266 int target = find_lowest_rq(p);
1268 if (target != -1)
1269 cpu = target;
1271 rcu_read_unlock();
1273 out:
1274 return cpu;
1277 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1279 if (rq->curr->rt.nr_cpus_allowed == 1)
1280 return;
1282 if (p->rt.nr_cpus_allowed != 1
1283 && cpupri_find(&rq->rd->cpupri, p, NULL))
1284 return;
1286 if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1287 return;
1290 * There appears to be other cpus that can accept
1291 * current and none to run 'p', so lets reschedule
1292 * to try and push current away:
1294 requeue_task_rt(rq, p, 1);
1295 resched_task(rq->curr);
1298 #endif /* CONFIG_SMP */
1301 * Preempt the current task with a newly woken task if needed:
1303 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1305 if (p->prio < rq->curr->prio) {
1306 resched_task(rq->curr);
1307 return;
1310 #ifdef CONFIG_SMP
1312 * If:
1314 * - the newly woken task is of equal priority to the current task
1315 * - the newly woken task is non-migratable while current is migratable
1316 * - current will be preempted on the next reschedule
1318 * we should check to see if current can readily move to a different
1319 * cpu. If so, we will reschedule to allow the push logic to try
1320 * to move current somewhere else, making room for our non-migratable
1321 * task.
1323 if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1324 check_preempt_equal_prio(rq, p);
1325 #endif
1328 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1329 struct rt_rq *rt_rq)
1331 struct rt_prio_array *array = &rt_rq->active;
1332 struct sched_rt_entity *next = NULL;
1333 struct list_head *queue;
1334 int idx;
1336 idx = sched_find_first_bit(array->bitmap);
1337 BUG_ON(idx >= MAX_RT_PRIO);
1339 queue = array->queue + idx;
1340 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1342 return next;
1345 static struct task_struct *_pick_next_task_rt(struct rq *rq)
1347 struct sched_rt_entity *rt_se;
1348 struct task_struct *p;
1349 struct rt_rq *rt_rq;
1351 rt_rq = &rq->rt;
1353 if (!rt_rq->rt_nr_running)
1354 return NULL;
1356 if (rt_rq_throttled(rt_rq))
1357 return NULL;
1359 do {
1360 rt_se = pick_next_rt_entity(rq, rt_rq);
1361 BUG_ON(!rt_se);
1362 rt_rq = group_rt_rq(rt_se);
1363 } while (rt_rq);
1365 p = rt_task_of(rt_se);
1366 p->se.exec_start = rq->clock_task;
1368 return p;
1371 static struct task_struct *pick_next_task_rt(struct rq *rq)
1373 struct task_struct *p = _pick_next_task_rt(rq);
1375 /* The running task is never eligible for pushing */
1376 if (p)
1377 dequeue_pushable_task(rq, p);
1379 #ifdef CONFIG_SMP
1381 * We detect this state here so that we can avoid taking the RQ
1382 * lock again later if there is no need to push
1384 rq->post_schedule = has_pushable_tasks(rq);
1385 #endif
1387 return p;
1390 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1392 update_curr_rt(rq);
1395 * The previous task needs to be made eligible for pushing
1396 * if it is still active
1398 if (on_rt_rq(&p->rt) && p->rt.nr_cpus_allowed > 1)
1399 enqueue_pushable_task(rq, p);
1402 #ifdef CONFIG_SMP
1404 /* Only try algorithms three times */
1405 #define RT_MAX_TRIES 3
1407 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1409 if (!task_running(rq, p) &&
1410 (cpu < 0 || cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) &&
1411 (p->rt.nr_cpus_allowed > 1))
1412 return 1;
1413 return 0;
1416 /* Return the second highest RT task, NULL otherwise */
1417 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
1419 struct task_struct *next = NULL;
1420 struct sched_rt_entity *rt_se;
1421 struct rt_prio_array *array;
1422 struct rt_rq *rt_rq;
1423 int idx;
1425 for_each_leaf_rt_rq(rt_rq, rq) {
1426 array = &rt_rq->active;
1427 idx = sched_find_first_bit(array->bitmap);
1428 next_idx:
1429 if (idx >= MAX_RT_PRIO)
1430 continue;
1431 if (next && next->prio <= idx)
1432 continue;
1433 list_for_each_entry(rt_se, array->queue + idx, run_list) {
1434 struct task_struct *p;
1436 if (!rt_entity_is_task(rt_se))
1437 continue;
1439 p = rt_task_of(rt_se);
1440 if (pick_rt_task(rq, p, cpu)) {
1441 next = p;
1442 break;
1445 if (!next) {
1446 idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
1447 goto next_idx;
1451 return next;
1454 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1456 static int find_lowest_rq(struct task_struct *task)
1458 struct sched_domain *sd;
1459 struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
1460 int this_cpu = smp_processor_id();
1461 int cpu = task_cpu(task);
1463 /* Make sure the mask is initialized first */
1464 if (unlikely(!lowest_mask))
1465 return -1;
1467 if (task->rt.nr_cpus_allowed == 1)
1468 return -1; /* No other targets possible */
1470 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1471 return -1; /* No targets found */
1474 * At this point we have built a mask of cpus representing the
1475 * lowest priority tasks in the system. Now we want to elect
1476 * the best one based on our affinity and topology.
1478 * We prioritize the last cpu that the task executed on since
1479 * it is most likely cache-hot in that location.
1481 if (cpumask_test_cpu(cpu, lowest_mask))
1482 return cpu;
1485 * Otherwise, we consult the sched_domains span maps to figure
1486 * out which cpu is logically closest to our hot cache data.
1488 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1489 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1491 rcu_read_lock();
1492 for_each_domain(cpu, sd) {
1493 if (sd->flags & SD_WAKE_AFFINE) {
1494 int best_cpu;
1497 * "this_cpu" is cheaper to preempt than a
1498 * remote processor.
1500 if (this_cpu != -1 &&
1501 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1502 rcu_read_unlock();
1503 return this_cpu;
1506 best_cpu = cpumask_first_and(lowest_mask,
1507 sched_domain_span(sd));
1508 if (best_cpu < nr_cpu_ids) {
1509 rcu_read_unlock();
1510 return best_cpu;
1514 rcu_read_unlock();
1517 * And finally, if there were no matches within the domains
1518 * just give the caller *something* to work with from the compatible
1519 * locations.
1521 if (this_cpu != -1)
1522 return this_cpu;
1524 cpu = cpumask_any(lowest_mask);
1525 if (cpu < nr_cpu_ids)
1526 return cpu;
1527 return -1;
1530 /* Will lock the rq it finds */
1531 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1533 struct rq *lowest_rq = NULL;
1534 int tries;
1535 int cpu;
1537 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1538 cpu = find_lowest_rq(task);
1540 if ((cpu == -1) || (cpu == rq->cpu))
1541 break;
1543 lowest_rq = cpu_rq(cpu);
1545 /* if the prio of this runqueue changed, try again */
1546 if (double_lock_balance(rq, lowest_rq)) {
1548 * We had to unlock the run queue. In
1549 * the mean time, task could have
1550 * migrated already or had its affinity changed.
1551 * Also make sure that it wasn't scheduled on its rq.
1553 if (unlikely(task_rq(task) != rq ||
1554 !cpumask_test_cpu(lowest_rq->cpu,
1555 tsk_cpus_allowed(task)) ||
1556 task_running(rq, task) ||
1557 !task->on_rq)) {
1559 raw_spin_unlock(&lowest_rq->lock);
1560 lowest_rq = NULL;
1561 break;
1565 /* If this rq is still suitable use it. */
1566 if (lowest_rq->rt.highest_prio.curr > task->prio)
1567 break;
1569 /* try again */
1570 double_unlock_balance(rq, lowest_rq);
1571 lowest_rq = NULL;
1574 return lowest_rq;
1577 static struct task_struct *pick_next_pushable_task(struct rq *rq)
1579 struct task_struct *p;
1581 if (!has_pushable_tasks(rq))
1582 return NULL;
1584 p = plist_first_entry(&rq->rt.pushable_tasks,
1585 struct task_struct, pushable_tasks);
1587 BUG_ON(rq->cpu != task_cpu(p));
1588 BUG_ON(task_current(rq, p));
1589 BUG_ON(p->rt.nr_cpus_allowed <= 1);
1591 BUG_ON(!p->on_rq);
1592 BUG_ON(!rt_task(p));
1594 return p;
1598 * If the current CPU has more than one RT task, see if the non
1599 * running task can migrate over to a CPU that is running a task
1600 * of lesser priority.
1602 static int push_rt_task(struct rq *rq)
1604 struct task_struct *next_task;
1605 struct rq *lowest_rq;
1606 int ret = 0;
1608 if (!rq->rt.overloaded)
1609 return 0;
1611 next_task = pick_next_pushable_task(rq);
1612 if (!next_task)
1613 return 0;
1615 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1616 if (unlikely(task_running(rq, next_task)))
1617 return 0;
1618 #endif
1620 retry:
1621 if (unlikely(next_task == rq->curr)) {
1622 WARN_ON(1);
1623 return 0;
1627 * It's possible that the next_task slipped in of
1628 * higher priority than current. If that's the case
1629 * just reschedule current.
1631 if (unlikely(next_task->prio < rq->curr->prio)) {
1632 resched_task(rq->curr);
1633 return 0;
1636 /* We might release rq lock */
1637 get_task_struct(next_task);
1639 /* find_lock_lowest_rq locks the rq if found */
1640 lowest_rq = find_lock_lowest_rq(next_task, rq);
1641 if (!lowest_rq) {
1642 struct task_struct *task;
1644 * find_lock_lowest_rq releases rq->lock
1645 * so it is possible that next_task has migrated.
1647 * We need to make sure that the task is still on the same
1648 * run-queue and is also still the next task eligible for
1649 * pushing.
1651 task = pick_next_pushable_task(rq);
1652 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1654 * The task hasn't migrated, and is still the next
1655 * eligible task, but we failed to find a run-queue
1656 * to push it to. Do not retry in this case, since
1657 * other cpus will pull from us when ready.
1659 goto out;
1662 if (!task)
1663 /* No more tasks, just exit */
1664 goto out;
1667 * Something has shifted, try again.
1669 put_task_struct(next_task);
1670 next_task = task;
1671 goto retry;
1674 deactivate_task(rq, next_task, 0);
1675 set_task_cpu(next_task, lowest_rq->cpu);
1676 activate_task(lowest_rq, next_task, 0);
1677 ret = 1;
1679 resched_task(lowest_rq->curr);
1681 double_unlock_balance(rq, lowest_rq);
1683 out:
1684 put_task_struct(next_task);
1686 return ret;
1689 static void push_rt_tasks(struct rq *rq)
1691 /* push_rt_task will return true if it moved an RT */
1692 while (push_rt_task(rq))
1696 static int pull_rt_task(struct rq *this_rq)
1698 int this_cpu = this_rq->cpu, ret = 0, cpu;
1699 struct task_struct *p;
1700 struct rq *src_rq;
1702 if (likely(!rt_overloaded(this_rq)))
1703 return 0;
1705 for_each_cpu(cpu, this_rq->rd->rto_mask) {
1706 if (this_cpu == cpu)
1707 continue;
1709 src_rq = cpu_rq(cpu);
1712 * Don't bother taking the src_rq->lock if the next highest
1713 * task is known to be lower-priority than our current task.
1714 * This may look racy, but if this value is about to go
1715 * logically higher, the src_rq will push this task away.
1716 * And if its going logically lower, we do not care
1718 if (src_rq->rt.highest_prio.next >=
1719 this_rq->rt.highest_prio.curr)
1720 continue;
1723 * We can potentially drop this_rq's lock in
1724 * double_lock_balance, and another CPU could
1725 * alter this_rq
1727 double_lock_balance(this_rq, src_rq);
1730 * Are there still pullable RT tasks?
1732 if (src_rq->rt.rt_nr_running <= 1)
1733 goto skip;
1735 p = pick_next_highest_task_rt(src_rq, this_cpu);
1738 * Do we have an RT task that preempts
1739 * the to-be-scheduled task?
1741 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
1742 WARN_ON(p == src_rq->curr);
1743 WARN_ON(!p->on_rq);
1746 * There's a chance that p is higher in priority
1747 * than what's currently running on its cpu.
1748 * This is just that p is wakeing up and hasn't
1749 * had a chance to schedule. We only pull
1750 * p if it is lower in priority than the
1751 * current task on the run queue
1753 if (p->prio < src_rq->curr->prio)
1754 goto skip;
1756 ret = 1;
1758 deactivate_task(src_rq, p, 0);
1759 set_task_cpu(p, this_cpu);
1760 activate_task(this_rq, p, 0);
1762 * We continue with the search, just in
1763 * case there's an even higher prio task
1764 * in another runqueue. (low likelihood
1765 * but possible)
1768 skip:
1769 double_unlock_balance(this_rq, src_rq);
1772 return ret;
1775 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1777 /* Try to pull RT tasks here if we lower this rq's prio */
1778 if (rq->rt.highest_prio.curr > prev->prio)
1779 pull_rt_task(rq);
1782 static void post_schedule_rt(struct rq *rq)
1784 push_rt_tasks(rq);
1788 * If we are not running and we are not going to reschedule soon, we should
1789 * try to push tasks away now
1791 static void task_woken_rt(struct rq *rq, struct task_struct *p)
1793 if (!task_running(rq, p) &&
1794 !test_tsk_need_resched(rq->curr) &&
1795 has_pushable_tasks(rq) &&
1796 p->rt.nr_cpus_allowed > 1 &&
1797 rt_task(rq->curr) &&
1798 (rq->curr->rt.nr_cpus_allowed < 2 ||
1799 rq->curr->prio <= p->prio))
1800 push_rt_tasks(rq);
1803 static void set_cpus_allowed_rt(struct task_struct *p,
1804 const struct cpumask *new_mask)
1806 struct rq *rq;
1807 int weight;
1809 BUG_ON(!rt_task(p));
1811 if (!p->on_rq)
1812 return;
1814 weight = cpumask_weight(new_mask);
1817 * Only update if the process changes its state from whether it
1818 * can migrate or not.
1820 if ((p->rt.nr_cpus_allowed > 1) == (weight > 1))
1821 return;
1823 rq = task_rq(p);
1826 * The process used to be able to migrate OR it can now migrate
1828 if (weight <= 1) {
1829 if (!task_current(rq, p))
1830 dequeue_pushable_task(rq, p);
1831 BUG_ON(!rq->rt.rt_nr_migratory);
1832 rq->rt.rt_nr_migratory--;
1833 } else {
1834 if (!task_current(rq, p))
1835 enqueue_pushable_task(rq, p);
1836 rq->rt.rt_nr_migratory++;
1839 update_rt_migration(&rq->rt);
1842 /* Assumes rq->lock is held */
1843 static void rq_online_rt(struct rq *rq)
1845 if (rq->rt.overloaded)
1846 rt_set_overload(rq);
1848 __enable_runtime(rq);
1850 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1853 /* Assumes rq->lock is held */
1854 static void rq_offline_rt(struct rq *rq)
1856 if (rq->rt.overloaded)
1857 rt_clear_overload(rq);
1859 __disable_runtime(rq);
1861 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1865 * When switch from the rt queue, we bring ourselves to a position
1866 * that we might want to pull RT tasks from other runqueues.
1868 static void switched_from_rt(struct rq *rq, struct task_struct *p)
1871 * If there are other RT tasks then we will reschedule
1872 * and the scheduling of the other RT tasks will handle
1873 * the balancing. But if we are the last RT task
1874 * we may need to handle the pulling of RT tasks
1875 * now.
1877 if (p->on_rq && !rq->rt.rt_nr_running)
1878 pull_rt_task(rq);
1881 void init_sched_rt_class(void)
1883 unsigned int i;
1885 for_each_possible_cpu(i) {
1886 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
1887 GFP_KERNEL, cpu_to_node(i));
1890 #endif /* CONFIG_SMP */
1893 * When switching a task to RT, we may overload the runqueue
1894 * with RT tasks. In this case we try to push them off to
1895 * other runqueues.
1897 static void switched_to_rt(struct rq *rq, struct task_struct *p)
1899 int check_resched = 1;
1902 * If we are already running, then there's nothing
1903 * that needs to be done. But if we are not running
1904 * we may need to preempt the current running task.
1905 * If that current running task is also an RT task
1906 * then see if we can move to another run queue.
1908 if (p->on_rq && rq->curr != p) {
1909 #ifdef CONFIG_SMP
1910 if (rq->rt.overloaded && push_rt_task(rq) &&
1911 /* Don't resched if we changed runqueues */
1912 rq != task_rq(p))
1913 check_resched = 0;
1914 #endif /* CONFIG_SMP */
1915 if (check_resched && p->prio < rq->curr->prio)
1916 resched_task(rq->curr);
1921 * Priority of the task has changed. This may cause
1922 * us to initiate a push or pull.
1924 static void
1925 prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
1927 if (!p->on_rq)
1928 return;
1930 if (rq->curr == p) {
1931 #ifdef CONFIG_SMP
1933 * If our priority decreases while running, we
1934 * may need to pull tasks to this runqueue.
1936 if (oldprio < p->prio)
1937 pull_rt_task(rq);
1939 * If there's a higher priority task waiting to run
1940 * then reschedule. Note, the above pull_rt_task
1941 * can release the rq lock and p could migrate.
1942 * Only reschedule if p is still on the same runqueue.
1944 if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
1945 resched_task(p);
1946 #else
1947 /* For UP simply resched on drop of prio */
1948 if (oldprio < p->prio)
1949 resched_task(p);
1950 #endif /* CONFIG_SMP */
1951 } else {
1953 * This task is not running, but if it is
1954 * greater than the current running task
1955 * then reschedule.
1957 if (p->prio < rq->curr->prio)
1958 resched_task(rq->curr);
1962 static void watchdog(struct rq *rq, struct task_struct *p)
1964 unsigned long soft, hard;
1966 /* max may change after cur was read, this will be fixed next tick */
1967 soft = task_rlimit(p, RLIMIT_RTTIME);
1968 hard = task_rlimit_max(p, RLIMIT_RTTIME);
1970 if (soft != RLIM_INFINITY) {
1971 unsigned long next;
1973 p->rt.timeout++;
1974 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1975 if (p->rt.timeout > next)
1976 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
1980 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1982 update_curr_rt(rq);
1984 watchdog(rq, p);
1987 * RR tasks need a special form of timeslice management.
1988 * FIFO tasks have no timeslices.
1990 if (p->policy != SCHED_RR)
1991 return;
1993 if (--p->rt.time_slice)
1994 return;
1996 p->rt.time_slice = RR_TIMESLICE;
1999 * Requeue to the end of queue if we are not the only element
2000 * on the queue:
2002 if (p->rt.run_list.prev != p->rt.run_list.next) {
2003 requeue_task_rt(rq, p, 0);
2004 set_tsk_need_resched(p);
2008 static void set_curr_task_rt(struct rq *rq)
2010 struct task_struct *p = rq->curr;
2012 p->se.exec_start = rq->clock_task;
2014 /* The running task is never eligible for pushing */
2015 dequeue_pushable_task(rq, p);
2018 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
2021 * Time slice is 0 for SCHED_FIFO tasks
2023 if (task->policy == SCHED_RR)
2024 return RR_TIMESLICE;
2025 else
2026 return 0;
2029 const struct sched_class rt_sched_class = {
2030 .next = &fair_sched_class,
2031 .enqueue_task = enqueue_task_rt,
2032 .dequeue_task = dequeue_task_rt,
2033 .yield_task = yield_task_rt,
2035 .check_preempt_curr = check_preempt_curr_rt,
2037 .pick_next_task = pick_next_task_rt,
2038 .put_prev_task = put_prev_task_rt,
2040 #ifdef CONFIG_SMP
2041 .select_task_rq = select_task_rq_rt,
2043 .set_cpus_allowed = set_cpus_allowed_rt,
2044 .rq_online = rq_online_rt,
2045 .rq_offline = rq_offline_rt,
2046 .pre_schedule = pre_schedule_rt,
2047 .post_schedule = post_schedule_rt,
2048 .task_woken = task_woken_rt,
2049 .switched_from = switched_from_rt,
2050 #endif
2052 .set_curr_task = set_curr_task_rt,
2053 .task_tick = task_tick_rt,
2055 .get_rr_interval = get_rr_interval_rt,
2057 .prio_changed = prio_changed_rt,
2058 .switched_to = switched_to_rt,
2061 #ifdef CONFIG_SCHED_DEBUG
2062 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
2064 void print_rt_stats(struct seq_file *m, int cpu)
2066 rt_rq_iter_t iter;
2067 struct rt_rq *rt_rq;
2069 rcu_read_lock();
2070 for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
2071 print_rt_rq(m, cpu, rt_rq);
2072 rcu_read_unlock();
2074 #endif /* CONFIG_SCHED_DEBUG */