2 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
8 #include <linux/slab.h>
10 int sched_rr_timeslice = RR_TIMESLICE;
12 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
14 struct rt_bandwidth def_rt_bandwidth;
16 static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
18 struct rt_bandwidth *rt_b =
19 container_of(timer, struct rt_bandwidth, rt_period_timer);
25 now = hrtimer_cb_get_time(timer);
26 overrun = hrtimer_forward(timer, now, rt_b->rt_period);
31 idle = do_sched_rt_period_timer(rt_b, overrun);
34 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
37 void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
39 rt_b->rt_period = ns_to_ktime(period);
40 rt_b->rt_runtime = runtime;
42 raw_spin_lock_init(&rt_b->rt_runtime_lock);
44 hrtimer_init(&rt_b->rt_period_timer,
45 CLOCK_MONOTONIC, HRTIMER_MODE_REL);
46 rt_b->rt_period_timer.function = sched_rt_period_timer;
49 static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
51 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
54 if (hrtimer_active(&rt_b->rt_period_timer))
57 raw_spin_lock(&rt_b->rt_runtime_lock);
58 start_bandwidth_timer(&rt_b->rt_period_timer, rt_b->rt_period);
59 raw_spin_unlock(&rt_b->rt_runtime_lock);
62 void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
64 struct rt_prio_array *array;
67 array = &rt_rq->active;
68 for (i = 0; i < MAX_RT_PRIO; i++) {
69 INIT_LIST_HEAD(array->queue + i);
70 __clear_bit(i, array->bitmap);
72 /* delimiter for bitsearch: */
73 __set_bit(MAX_RT_PRIO, array->bitmap);
75 #if defined CONFIG_SMP
76 rt_rq->highest_prio.curr = MAX_RT_PRIO;
77 rt_rq->highest_prio.next = MAX_RT_PRIO;
78 rt_rq->rt_nr_migratory = 0;
79 rt_rq->overloaded = 0;
80 plist_head_init(&rt_rq->pushable_tasks);
84 rt_rq->rt_throttled = 0;
85 rt_rq->rt_runtime = 0;
86 raw_spin_lock_init(&rt_rq->rt_runtime_lock);
89 #ifdef CONFIG_RT_GROUP_SCHED
90 static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
92 hrtimer_cancel(&rt_b->rt_period_timer);
95 #define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
97 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
99 #ifdef CONFIG_SCHED_DEBUG
100 WARN_ON_ONCE(!rt_entity_is_task(rt_se));
102 return container_of(rt_se, struct task_struct, rt);
105 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
110 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
115 void free_rt_sched_group(struct task_group *tg)
120 destroy_rt_bandwidth(&tg->rt_bandwidth);
122 for_each_possible_cpu(i) {
133 void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
134 struct sched_rt_entity *rt_se, int cpu,
135 struct sched_rt_entity *parent)
137 struct rq *rq = cpu_rq(cpu);
139 rt_rq->highest_prio.curr = MAX_RT_PRIO;
140 rt_rq->rt_nr_boosted = 0;
144 tg->rt_rq[cpu] = rt_rq;
145 tg->rt_se[cpu] = rt_se;
151 rt_se->rt_rq = &rq->rt;
153 rt_se->rt_rq = parent->my_q;
156 rt_se->parent = parent;
157 INIT_LIST_HEAD(&rt_se->run_list);
160 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
163 struct sched_rt_entity *rt_se;
166 tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
169 tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
173 init_rt_bandwidth(&tg->rt_bandwidth,
174 ktime_to_ns(def_rt_bandwidth.rt_period), 0);
176 for_each_possible_cpu(i) {
177 rt_rq = kzalloc_node(sizeof(struct rt_rq),
178 GFP_KERNEL, cpu_to_node(i));
182 rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
183 GFP_KERNEL, cpu_to_node(i));
187 init_rt_rq(rt_rq, cpu_rq(i));
188 rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
189 init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
200 #else /* CONFIG_RT_GROUP_SCHED */
202 #define rt_entity_is_task(rt_se) (1)
204 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
206 return container_of(rt_se, struct task_struct, rt);
209 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
211 return container_of(rt_rq, struct rq, rt);
214 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
216 struct task_struct *p = rt_task_of(rt_se);
217 struct rq *rq = task_rq(p);
222 void free_rt_sched_group(struct task_group *tg) { }
224 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
228 #endif /* CONFIG_RT_GROUP_SCHED */
232 static inline int rt_overloaded(struct rq *rq)
234 return atomic_read(&rq->rd->rto_count);
237 static inline void rt_set_overload(struct rq *rq)
242 cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
244 * Make sure the mask is visible before we set
245 * the overload count. That is checked to determine
246 * if we should look at the mask. It would be a shame
247 * if we looked at the mask, but the mask was not
251 atomic_inc(&rq->rd->rto_count);
254 static inline void rt_clear_overload(struct rq *rq)
259 /* the order here really doesn't matter */
260 atomic_dec(&rq->rd->rto_count);
261 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
264 static void update_rt_migration(struct rt_rq *rt_rq)
266 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
267 if (!rt_rq->overloaded) {
268 rt_set_overload(rq_of_rt_rq(rt_rq));
269 rt_rq->overloaded = 1;
271 } else if (rt_rq->overloaded) {
272 rt_clear_overload(rq_of_rt_rq(rt_rq));
273 rt_rq->overloaded = 0;
277 static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
279 struct task_struct *p;
281 if (!rt_entity_is_task(rt_se))
284 p = rt_task_of(rt_se);
285 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
287 rt_rq->rt_nr_total++;
288 if (p->nr_cpus_allowed > 1)
289 rt_rq->rt_nr_migratory++;
291 update_rt_migration(rt_rq);
294 static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
296 struct task_struct *p;
298 if (!rt_entity_is_task(rt_se))
301 p = rt_task_of(rt_se);
302 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
304 rt_rq->rt_nr_total--;
305 if (p->nr_cpus_allowed > 1)
306 rt_rq->rt_nr_migratory--;
308 update_rt_migration(rt_rq);
311 static inline int has_pushable_tasks(struct rq *rq)
313 return !plist_head_empty(&rq->rt.pushable_tasks);
316 static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
318 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
319 plist_node_init(&p->pushable_tasks, p->prio);
320 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
322 /* Update the highest prio pushable task */
323 if (p->prio < rq->rt.highest_prio.next)
324 rq->rt.highest_prio.next = p->prio;
327 static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
329 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
331 /* Update the new highest prio pushable task */
332 if (has_pushable_tasks(rq)) {
333 p = plist_first_entry(&rq->rt.pushable_tasks,
334 struct task_struct, pushable_tasks);
335 rq->rt.highest_prio.next = p->prio;
337 rq->rt.highest_prio.next = MAX_RT_PRIO;
342 static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
346 static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
351 void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
356 void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
360 #endif /* CONFIG_SMP */
362 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
364 return !list_empty(&rt_se->run_list);
367 #ifdef CONFIG_RT_GROUP_SCHED
369 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
374 return rt_rq->rt_runtime;
377 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
379 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
382 typedef struct task_group *rt_rq_iter_t;
384 static inline struct task_group *next_task_group(struct task_group *tg)
387 tg = list_entry_rcu(tg->list.next,
388 typeof(struct task_group), list);
389 } while (&tg->list != &task_groups && task_group_is_autogroup(tg));
391 if (&tg->list == &task_groups)
397 #define for_each_rt_rq(rt_rq, iter, rq) \
398 for (iter = container_of(&task_groups, typeof(*iter), list); \
399 (iter = next_task_group(iter)) && \
400 (rt_rq = iter->rt_rq[cpu_of(rq)]);)
402 #define for_each_sched_rt_entity(rt_se) \
403 for (; rt_se; rt_se = rt_se->parent)
405 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
410 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
411 static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
413 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
415 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
416 struct sched_rt_entity *rt_se;
418 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
420 rt_se = rt_rq->tg->rt_se[cpu];
422 if (rt_rq->rt_nr_running) {
423 if (rt_se && !on_rt_rq(rt_se))
424 enqueue_rt_entity(rt_se, false);
425 if (rt_rq->highest_prio.curr < curr->prio)
430 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
432 struct sched_rt_entity *rt_se;
433 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
435 rt_se = rt_rq->tg->rt_se[cpu];
437 if (rt_se && on_rt_rq(rt_se))
438 dequeue_rt_entity(rt_se);
441 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
443 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
446 static int rt_se_boosted(struct sched_rt_entity *rt_se)
448 struct rt_rq *rt_rq = group_rt_rq(rt_se);
449 struct task_struct *p;
452 return !!rt_rq->rt_nr_boosted;
454 p = rt_task_of(rt_se);
455 return p->prio != p->normal_prio;
459 static inline const struct cpumask *sched_rt_period_mask(void)
461 return this_rq()->rd->span;
464 static inline const struct cpumask *sched_rt_period_mask(void)
466 return cpu_online_mask;
471 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
473 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
476 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
478 return &rt_rq->tg->rt_bandwidth;
481 #else /* !CONFIG_RT_GROUP_SCHED */
483 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
485 return rt_rq->rt_runtime;
488 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
490 return ktime_to_ns(def_rt_bandwidth.rt_period);
493 typedef struct rt_rq *rt_rq_iter_t;
495 #define for_each_rt_rq(rt_rq, iter, rq) \
496 for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
498 #define for_each_sched_rt_entity(rt_se) \
499 for (; rt_se; rt_se = NULL)
501 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
506 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
508 if (rt_rq->rt_nr_running)
509 resched_task(rq_of_rt_rq(rt_rq)->curr);
512 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
516 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
518 return rt_rq->rt_throttled;
521 static inline const struct cpumask *sched_rt_period_mask(void)
523 return cpu_online_mask;
527 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
529 return &cpu_rq(cpu)->rt;
532 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
534 return &def_rt_bandwidth;
537 #endif /* CONFIG_RT_GROUP_SCHED */
541 * We ran out of runtime, see if we can borrow some from our neighbours.
543 static int do_balance_runtime(struct rt_rq *rt_rq)
545 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
546 struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;
547 int i, weight, more = 0;
550 weight = cpumask_weight(rd->span);
552 raw_spin_lock(&rt_b->rt_runtime_lock);
553 rt_period = ktime_to_ns(rt_b->rt_period);
554 for_each_cpu(i, rd->span) {
555 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
561 raw_spin_lock(&iter->rt_runtime_lock);
563 * Either all rqs have inf runtime and there's nothing to steal
564 * or __disable_runtime() below sets a specific rq to inf to
565 * indicate its been disabled and disalow stealing.
567 if (iter->rt_runtime == RUNTIME_INF)
571 * From runqueues with spare time, take 1/n part of their
572 * spare time, but no more than our period.
574 diff = iter->rt_runtime - iter->rt_time;
576 diff = div_u64((u64)diff, weight);
577 if (rt_rq->rt_runtime + diff > rt_period)
578 diff = rt_period - rt_rq->rt_runtime;
579 iter->rt_runtime -= diff;
580 rt_rq->rt_runtime += diff;
582 if (rt_rq->rt_runtime == rt_period) {
583 raw_spin_unlock(&iter->rt_runtime_lock);
588 raw_spin_unlock(&iter->rt_runtime_lock);
590 raw_spin_unlock(&rt_b->rt_runtime_lock);
596 * Ensure this RQ takes back all the runtime it lend to its neighbours.
598 static void __disable_runtime(struct rq *rq)
600 struct root_domain *rd = rq->rd;
604 if (unlikely(!scheduler_running))
607 for_each_rt_rq(rt_rq, iter, rq) {
608 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
612 raw_spin_lock(&rt_b->rt_runtime_lock);
613 raw_spin_lock(&rt_rq->rt_runtime_lock);
615 * Either we're all inf and nobody needs to borrow, or we're
616 * already disabled and thus have nothing to do, or we have
617 * exactly the right amount of runtime to take out.
619 if (rt_rq->rt_runtime == RUNTIME_INF ||
620 rt_rq->rt_runtime == rt_b->rt_runtime)
622 raw_spin_unlock(&rt_rq->rt_runtime_lock);
625 * Calculate the difference between what we started out with
626 * and what we current have, that's the amount of runtime
627 * we lend and now have to reclaim.
629 want = rt_b->rt_runtime - rt_rq->rt_runtime;
632 * Greedy reclaim, take back as much as we can.
634 for_each_cpu(i, rd->span) {
635 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
639 * Can't reclaim from ourselves or disabled runqueues.
641 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
644 raw_spin_lock(&iter->rt_runtime_lock);
646 diff = min_t(s64, iter->rt_runtime, want);
647 iter->rt_runtime -= diff;
650 iter->rt_runtime -= want;
653 raw_spin_unlock(&iter->rt_runtime_lock);
659 raw_spin_lock(&rt_rq->rt_runtime_lock);
661 * We cannot be left wanting - that would mean some runtime
662 * leaked out of the system.
667 * Disable all the borrow logic by pretending we have inf
668 * runtime - in which case borrowing doesn't make sense.
670 rt_rq->rt_runtime = RUNTIME_INF;
671 rt_rq->rt_throttled = 0;
672 raw_spin_unlock(&rt_rq->rt_runtime_lock);
673 raw_spin_unlock(&rt_b->rt_runtime_lock);
677 static void __enable_runtime(struct rq *rq)
682 if (unlikely(!scheduler_running))
686 * Reset each runqueue's bandwidth settings
688 for_each_rt_rq(rt_rq, iter, rq) {
689 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
691 raw_spin_lock(&rt_b->rt_runtime_lock);
692 raw_spin_lock(&rt_rq->rt_runtime_lock);
693 rt_rq->rt_runtime = rt_b->rt_runtime;
695 rt_rq->rt_throttled = 0;
696 raw_spin_unlock(&rt_rq->rt_runtime_lock);
697 raw_spin_unlock(&rt_b->rt_runtime_lock);
701 static int balance_runtime(struct rt_rq *rt_rq)
705 if (!sched_feat(RT_RUNTIME_SHARE))
708 if (rt_rq->rt_time > rt_rq->rt_runtime) {
709 raw_spin_unlock(&rt_rq->rt_runtime_lock);
710 more = do_balance_runtime(rt_rq);
711 raw_spin_lock(&rt_rq->rt_runtime_lock);
716 #else /* !CONFIG_SMP */
717 static inline int balance_runtime(struct rt_rq *rt_rq)
721 #endif /* CONFIG_SMP */
723 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
725 int i, idle = 1, throttled = 0;
726 const struct cpumask *span;
728 span = sched_rt_period_mask();
729 #ifdef CONFIG_RT_GROUP_SCHED
731 * FIXME: isolated CPUs should really leave the root task group,
732 * whether they are isolcpus or were isolated via cpusets, lest
733 * the timer run on a CPU which does not service all runqueues,
734 * potentially leaving other CPUs indefinitely throttled. If
735 * isolation is really required, the user will turn the throttle
736 * off to kill the perturbations it causes anyway. Meanwhile,
737 * this maintains functionality for boot and/or troubleshooting.
739 if (rt_b == &root_task_group.rt_bandwidth)
740 span = cpu_online_mask;
742 for_each_cpu(i, span) {
744 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
745 struct rq *rq = rq_of_rt_rq(rt_rq);
747 raw_spin_lock(&rq->lock);
748 if (rt_rq->rt_time) {
751 raw_spin_lock(&rt_rq->rt_runtime_lock);
752 if (rt_rq->rt_throttled)
753 balance_runtime(rt_rq);
754 runtime = rt_rq->rt_runtime;
755 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
756 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
757 rt_rq->rt_throttled = 0;
761 * Force a clock update if the CPU was idle,
762 * lest wakeup -> unthrottle time accumulate.
764 if (rt_rq->rt_nr_running && rq->curr == rq->idle)
765 rq->skip_clock_update = -1;
767 if (rt_rq->rt_time || rt_rq->rt_nr_running)
769 raw_spin_unlock(&rt_rq->rt_runtime_lock);
770 } else if (rt_rq->rt_nr_running) {
772 if (!rt_rq_throttled(rt_rq))
775 if (rt_rq->rt_throttled)
779 sched_rt_rq_enqueue(rt_rq);
780 raw_spin_unlock(&rq->lock);
783 if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
789 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
791 #ifdef CONFIG_RT_GROUP_SCHED
792 struct rt_rq *rt_rq = group_rt_rq(rt_se);
795 return rt_rq->highest_prio.curr;
798 return rt_task_of(rt_se)->prio;
801 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
803 u64 runtime = sched_rt_runtime(rt_rq);
805 if (rt_rq->rt_throttled)
806 return rt_rq_throttled(rt_rq);
808 if (runtime >= sched_rt_period(rt_rq))
811 balance_runtime(rt_rq);
812 runtime = sched_rt_runtime(rt_rq);
813 if (runtime == RUNTIME_INF)
816 if (rt_rq->rt_time > runtime) {
817 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
820 * Don't actually throttle groups that have no runtime assigned
821 * but accrue some time due to boosting.
823 if (likely(rt_b->rt_runtime)) {
824 static bool once = false;
826 rt_rq->rt_throttled = 1;
830 printk_sched("sched: RT throttling activated\n");
834 * In case we did anyway, make it go away,
835 * replenishment is a joke, since it will replenish us
841 if (rt_rq_throttled(rt_rq)) {
842 sched_rt_rq_dequeue(rt_rq);
851 * Update the current task's runtime statistics. Skip current tasks that
852 * are not in our scheduling class.
854 static void update_curr_rt(struct rq *rq)
856 struct task_struct *curr = rq->curr;
857 struct sched_rt_entity *rt_se = &curr->rt;
858 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
861 if (curr->sched_class != &rt_sched_class)
864 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
865 if (unlikely((s64)delta_exec <= 0))
868 schedstat_set(curr->se.statistics.exec_max,
869 max(curr->se.statistics.exec_max, delta_exec));
871 curr->se.sum_exec_runtime += delta_exec;
872 account_group_exec_runtime(curr, delta_exec);
874 curr->se.exec_start = rq_clock_task(rq);
875 cpuacct_charge(curr, delta_exec);
877 sched_rt_avg_update(rq, delta_exec);
879 if (!rt_bandwidth_enabled())
882 for_each_sched_rt_entity(rt_se) {
883 rt_rq = rt_rq_of_se(rt_se);
885 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
886 raw_spin_lock(&rt_rq->rt_runtime_lock);
887 rt_rq->rt_time += delta_exec;
888 if (sched_rt_runtime_exceeded(rt_rq))
890 raw_spin_unlock(&rt_rq->rt_runtime_lock);
895 #if defined CONFIG_SMP
898 inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
900 struct rq *rq = rq_of_rt_rq(rt_rq);
902 if (rq->online && prio < prev_prio)
903 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
907 dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
909 struct rq *rq = rq_of_rt_rq(rt_rq);
911 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
912 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
915 #else /* CONFIG_SMP */
918 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
920 void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
922 #endif /* CONFIG_SMP */
924 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
926 inc_rt_prio(struct rt_rq *rt_rq, int prio)
928 int prev_prio = rt_rq->highest_prio.curr;
930 if (prio < prev_prio)
931 rt_rq->highest_prio.curr = prio;
933 inc_rt_prio_smp(rt_rq, prio, prev_prio);
937 dec_rt_prio(struct rt_rq *rt_rq, int prio)
939 int prev_prio = rt_rq->highest_prio.curr;
941 if (rt_rq->rt_nr_running) {
943 WARN_ON(prio < prev_prio);
946 * This may have been our highest task, and therefore
947 * we may have some recomputation to do
949 if (prio == prev_prio) {
950 struct rt_prio_array *array = &rt_rq->active;
952 rt_rq->highest_prio.curr =
953 sched_find_first_bit(array->bitmap);
957 rt_rq->highest_prio.curr = MAX_RT_PRIO;
959 dec_rt_prio_smp(rt_rq, prio, prev_prio);
964 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
965 static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
967 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
969 #ifdef CONFIG_RT_GROUP_SCHED
972 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
974 if (rt_se_boosted(rt_se))
975 rt_rq->rt_nr_boosted++;
978 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
982 dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
984 if (rt_se_boosted(rt_se))
985 rt_rq->rt_nr_boosted--;
987 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
990 #else /* CONFIG_RT_GROUP_SCHED */
993 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
995 start_rt_bandwidth(&def_rt_bandwidth);
999 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1001 #endif /* CONFIG_RT_GROUP_SCHED */
1004 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1006 int prio = rt_se_prio(rt_se);
1008 WARN_ON(!rt_prio(prio));
1009 rt_rq->rt_nr_running++;
1011 inc_rt_prio(rt_rq, prio);
1012 inc_rt_migration(rt_se, rt_rq);
1013 inc_rt_group(rt_se, rt_rq);
1017 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1019 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
1020 WARN_ON(!rt_rq->rt_nr_running);
1021 rt_rq->rt_nr_running--;
1023 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
1024 dec_rt_migration(rt_se, rt_rq);
1025 dec_rt_group(rt_se, rt_rq);
1028 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1030 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1031 struct rt_prio_array *array = &rt_rq->active;
1032 struct rt_rq *group_rq = group_rt_rq(rt_se);
1033 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1036 * Don't enqueue the group if its throttled, or when empty.
1037 * The latter is a consequence of the former when a child group
1038 * get throttled and the current group doesn't have any other
1041 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
1045 list_add(&rt_se->run_list, queue);
1047 list_add_tail(&rt_se->run_list, queue);
1048 __set_bit(rt_se_prio(rt_se), array->bitmap);
1050 inc_rt_tasks(rt_se, rt_rq);
1053 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
1055 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1056 struct rt_prio_array *array = &rt_rq->active;
1058 list_del_init(&rt_se->run_list);
1059 if (list_empty(array->queue + rt_se_prio(rt_se)))
1060 __clear_bit(rt_se_prio(rt_se), array->bitmap);
1062 dec_rt_tasks(rt_se, rt_rq);
1066 * Because the prio of an upper entry depends on the lower
1067 * entries, we must remove entries top - down.
1069 static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
1071 struct sched_rt_entity *back = NULL;
1073 for_each_sched_rt_entity(rt_se) {
1078 for (rt_se = back; rt_se; rt_se = rt_se->back) {
1079 if (on_rt_rq(rt_se))
1080 __dequeue_rt_entity(rt_se);
1084 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1086 dequeue_rt_stack(rt_se);
1087 for_each_sched_rt_entity(rt_se)
1088 __enqueue_rt_entity(rt_se, head);
1091 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
1093 dequeue_rt_stack(rt_se);
1095 for_each_sched_rt_entity(rt_se) {
1096 struct rt_rq *rt_rq = group_rt_rq(rt_se);
1098 if (rt_rq && rt_rq->rt_nr_running)
1099 __enqueue_rt_entity(rt_se, false);
1104 * Adding/removing a task to/from a priority array:
1107 enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1109 struct sched_rt_entity *rt_se = &p->rt;
1111 if (flags & ENQUEUE_WAKEUP)
1114 enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
1116 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1117 enqueue_pushable_task(rq, p);
1122 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1124 struct sched_rt_entity *rt_se = &p->rt;
1127 dequeue_rt_entity(rt_se);
1129 dequeue_pushable_task(rq, p);
1135 * Put task to the head or the end of the run list without the overhead of
1136 * dequeue followed by enqueue.
1139 requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
1141 if (on_rt_rq(rt_se)) {
1142 struct rt_prio_array *array = &rt_rq->active;
1143 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1146 list_move(&rt_se->run_list, queue);
1148 list_move_tail(&rt_se->run_list, queue);
1152 static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
1154 struct sched_rt_entity *rt_se = &p->rt;
1155 struct rt_rq *rt_rq;
1157 for_each_sched_rt_entity(rt_se) {
1158 rt_rq = rt_rq_of_se(rt_se);
1159 requeue_rt_entity(rt_rq, rt_se, head);
1163 static void yield_task_rt(struct rq *rq)
1165 requeue_task_rt(rq, rq->curr, 0);
1169 static int find_lowest_rq(struct task_struct *task);
1172 select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
1174 struct task_struct *curr;
1180 if (p->nr_cpus_allowed == 1)
1183 /* For anything but wake ups, just return the task_cpu */
1184 if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
1190 curr = ACCESS_ONCE(rq->curr); /* unlocked access */
1193 * If the current task on @p's runqueue is an RT task, then
1194 * try to see if we can wake this RT task up on another
1195 * runqueue. Otherwise simply start this RT task
1196 * on its current runqueue.
1198 * We want to avoid overloading runqueues. If the woken
1199 * task is a higher priority, then it will stay on this CPU
1200 * and the lower prio task should be moved to another CPU.
1201 * Even though this will probably make the lower prio task
1202 * lose its cache, we do not want to bounce a higher task
1203 * around just because it gave up its CPU, perhaps for a
1206 * For equal prio tasks, we just let the scheduler sort it out.
1208 * Otherwise, just let it ride on the affined RQ and the
1209 * post-schedule router will push the preempted task away
1211 * This test is optimistic, if we get it wrong the load-balancer
1212 * will have to sort it out.
1214 if (curr && unlikely(rt_task(curr)) &&
1215 (curr->nr_cpus_allowed < 2 ||
1216 curr->prio <= p->prio)) {
1217 int target = find_lowest_rq(p);
1228 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1230 if (rq->curr->nr_cpus_allowed == 1)
1233 if (p->nr_cpus_allowed != 1
1234 && cpupri_find(&rq->rd->cpupri, p, NULL))
1237 if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1241 * There appears to be other cpus that can accept
1242 * current and none to run 'p', so lets reschedule
1243 * to try and push current away:
1245 requeue_task_rt(rq, p, 1);
1246 resched_task(rq->curr);
1249 #endif /* CONFIG_SMP */
1252 * Preempt the current task with a newly woken task if needed:
1254 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1256 if (p->prio < rq->curr->prio) {
1257 resched_task(rq->curr);
1265 * - the newly woken task is of equal priority to the current task
1266 * - the newly woken task is non-migratable while current is migratable
1267 * - current will be preempted on the next reschedule
1269 * we should check to see if current can readily move to a different
1270 * cpu. If so, we will reschedule to allow the push logic to try
1271 * to move current somewhere else, making room for our non-migratable
1274 if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1275 check_preempt_equal_prio(rq, p);
1279 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1280 struct rt_rq *rt_rq)
1282 struct rt_prio_array *array = &rt_rq->active;
1283 struct sched_rt_entity *next = NULL;
1284 struct list_head *queue;
1287 idx = sched_find_first_bit(array->bitmap);
1288 BUG_ON(idx >= MAX_RT_PRIO);
1290 queue = array->queue + idx;
1291 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1296 static struct task_struct *_pick_next_task_rt(struct rq *rq)
1298 struct sched_rt_entity *rt_se;
1299 struct task_struct *p;
1300 struct rt_rq *rt_rq;
1304 if (!rt_rq->rt_nr_running)
1307 if (rt_rq_throttled(rt_rq))
1311 rt_se = pick_next_rt_entity(rq, rt_rq);
1313 rt_rq = group_rt_rq(rt_se);
1316 p = rt_task_of(rt_se);
1317 p->se.exec_start = rq_clock_task(rq);
1322 static struct task_struct *pick_next_task_rt(struct rq *rq)
1324 struct task_struct *p = _pick_next_task_rt(rq);
1326 /* The running task is never eligible for pushing */
1328 dequeue_pushable_task(rq, p);
1332 * We detect this state here so that we can avoid taking the RQ
1333 * lock again later if there is no need to push
1335 rq->post_schedule = has_pushable_tasks(rq);
1341 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1346 * The previous task needs to be made eligible for pushing
1347 * if it is still active
1349 if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
1350 enqueue_pushable_task(rq, p);
1355 /* Only try algorithms three times */
1356 #define RT_MAX_TRIES 3
1358 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1360 if (!task_running(rq, p) &&
1361 cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
1367 * Return the highest pushable rq's task, which is suitable to be executed
1368 * on the cpu, NULL otherwise
1370 static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
1372 struct plist_head *head = &rq->rt.pushable_tasks;
1373 struct task_struct *p;
1375 if (!has_pushable_tasks(rq))
1378 plist_for_each_entry(p, head, pushable_tasks) {
1379 if (pick_rt_task(rq, p, cpu))
1386 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1388 static int find_lowest_rq(struct task_struct *task)
1390 struct sched_domain *sd;
1391 struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
1392 int this_cpu = smp_processor_id();
1393 int cpu = task_cpu(task);
1395 /* Make sure the mask is initialized first */
1396 if (unlikely(!lowest_mask))
1399 if (task->nr_cpus_allowed == 1)
1400 return -1; /* No other targets possible */
1402 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1403 return -1; /* No targets found */
1406 * At this point we have built a mask of cpus representing the
1407 * lowest priority tasks in the system. Now we want to elect
1408 * the best one based on our affinity and topology.
1410 * We prioritize the last cpu that the task executed on since
1411 * it is most likely cache-hot in that location.
1413 if (cpumask_test_cpu(cpu, lowest_mask))
1417 * Otherwise, we consult the sched_domains span maps to figure
1418 * out which cpu is logically closest to our hot cache data.
1420 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1421 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1424 for_each_domain(cpu, sd) {
1425 if (sd->flags & SD_WAKE_AFFINE) {
1429 * "this_cpu" is cheaper to preempt than a
1432 if (this_cpu != -1 &&
1433 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1438 best_cpu = cpumask_first_and(lowest_mask,
1439 sched_domain_span(sd));
1440 if (best_cpu < nr_cpu_ids) {
1449 * And finally, if there were no matches within the domains
1450 * just give the caller *something* to work with from the compatible
1456 cpu = cpumask_any(lowest_mask);
1457 if (cpu < nr_cpu_ids)
1462 /* Will lock the rq it finds */
1463 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1465 struct rq *lowest_rq = NULL;
1469 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1470 cpu = find_lowest_rq(task);
1472 if ((cpu == -1) || (cpu == rq->cpu))
1475 lowest_rq = cpu_rq(cpu);
1477 /* if the prio of this runqueue changed, try again */
1478 if (double_lock_balance(rq, lowest_rq)) {
1480 * We had to unlock the run queue. In
1481 * the mean time, task could have
1482 * migrated already or had its affinity changed.
1483 * Also make sure that it wasn't scheduled on its rq.
1485 if (unlikely(task_rq(task) != rq ||
1486 !cpumask_test_cpu(lowest_rq->cpu,
1487 tsk_cpus_allowed(task)) ||
1488 task_running(rq, task) ||
1491 double_unlock_balance(rq, lowest_rq);
1497 /* If this rq is still suitable use it. */
1498 if (lowest_rq->rt.highest_prio.curr > task->prio)
1502 double_unlock_balance(rq, lowest_rq);
1509 static struct task_struct *pick_next_pushable_task(struct rq *rq)
1511 struct task_struct *p;
1513 if (!has_pushable_tasks(rq))
1516 p = plist_first_entry(&rq->rt.pushable_tasks,
1517 struct task_struct, pushable_tasks);
1519 BUG_ON(rq->cpu != task_cpu(p));
1520 BUG_ON(task_current(rq, p));
1521 BUG_ON(p->nr_cpus_allowed <= 1);
1524 BUG_ON(!rt_task(p));
1530 * If the current CPU has more than one RT task, see if the non
1531 * running task can migrate over to a CPU that is running a task
1532 * of lesser priority.
1534 static int push_rt_task(struct rq *rq)
1536 struct task_struct *next_task;
1537 struct rq *lowest_rq;
1540 if (!rq->rt.overloaded)
1543 next_task = pick_next_pushable_task(rq);
1548 if (unlikely(next_task == rq->curr)) {
1554 * It's possible that the next_task slipped in of
1555 * higher priority than current. If that's the case
1556 * just reschedule current.
1558 if (unlikely(next_task->prio < rq->curr->prio)) {
1559 resched_task(rq->curr);
1563 /* We might release rq lock */
1564 get_task_struct(next_task);
1566 /* find_lock_lowest_rq locks the rq if found */
1567 lowest_rq = find_lock_lowest_rq(next_task, rq);
1569 struct task_struct *task;
1571 * find_lock_lowest_rq releases rq->lock
1572 * so it is possible that next_task has migrated.
1574 * We need to make sure that the task is still on the same
1575 * run-queue and is also still the next task eligible for
1578 task = pick_next_pushable_task(rq);
1579 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1581 * The task hasn't migrated, and is still the next
1582 * eligible task, but we failed to find a run-queue
1583 * to push it to. Do not retry in this case, since
1584 * other cpus will pull from us when ready.
1590 /* No more tasks, just exit */
1594 * Something has shifted, try again.
1596 put_task_struct(next_task);
1601 deactivate_task(rq, next_task, 0);
1602 set_task_cpu(next_task, lowest_rq->cpu);
1603 activate_task(lowest_rq, next_task, 0);
1606 resched_task(lowest_rq->curr);
1608 double_unlock_balance(rq, lowest_rq);
1611 put_task_struct(next_task);
1616 static void push_rt_tasks(struct rq *rq)
1618 /* push_rt_task will return true if it moved an RT */
1619 while (push_rt_task(rq))
1623 static int pull_rt_task(struct rq *this_rq)
1625 int this_cpu = this_rq->cpu, ret = 0, cpu;
1626 struct task_struct *p;
1629 if (likely(!rt_overloaded(this_rq)))
1632 for_each_cpu(cpu, this_rq->rd->rto_mask) {
1633 if (this_cpu == cpu)
1636 src_rq = cpu_rq(cpu);
1639 * Don't bother taking the src_rq->lock if the next highest
1640 * task is known to be lower-priority than our current task.
1641 * This may look racy, but if this value is about to go
1642 * logically higher, the src_rq will push this task away.
1643 * And if its going logically lower, we do not care
1645 if (src_rq->rt.highest_prio.next >=
1646 this_rq->rt.highest_prio.curr)
1650 * We can potentially drop this_rq's lock in
1651 * double_lock_balance, and another CPU could
1654 double_lock_balance(this_rq, src_rq);
1657 * We can pull only a task, which is pushable
1658 * on its rq, and no others.
1660 p = pick_highest_pushable_task(src_rq, this_cpu);
1663 * Do we have an RT task that preempts
1664 * the to-be-scheduled task?
1666 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
1667 WARN_ON(p == src_rq->curr);
1671 * There's a chance that p is higher in priority
1672 * than what's currently running on its cpu.
1673 * This is just that p is wakeing up and hasn't
1674 * had a chance to schedule. We only pull
1675 * p if it is lower in priority than the
1676 * current task on the run queue
1678 if (p->prio < src_rq->curr->prio)
1683 deactivate_task(src_rq, p, 0);
1684 set_task_cpu(p, this_cpu);
1685 activate_task(this_rq, p, 0);
1687 * We continue with the search, just in
1688 * case there's an even higher prio task
1689 * in another runqueue. (low likelihood
1694 double_unlock_balance(this_rq, src_rq);
1700 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1702 /* Try to pull RT tasks here if we lower this rq's prio */
1703 if (rq->rt.highest_prio.curr > prev->prio)
1707 static void post_schedule_rt(struct rq *rq)
1713 * If we are not running and we are not going to reschedule soon, we should
1714 * try to push tasks away now
1716 static void task_woken_rt(struct rq *rq, struct task_struct *p)
1718 if (!task_running(rq, p) &&
1719 !test_tsk_need_resched(rq->curr) &&
1720 has_pushable_tasks(rq) &&
1721 p->nr_cpus_allowed > 1 &&
1722 rt_task(rq->curr) &&
1723 (rq->curr->nr_cpus_allowed < 2 ||
1724 rq->curr->prio <= p->prio))
1728 static void set_cpus_allowed_rt(struct task_struct *p,
1729 const struct cpumask *new_mask)
1734 BUG_ON(!rt_task(p));
1739 weight = cpumask_weight(new_mask);
1742 * Only update if the process changes its state from whether it
1743 * can migrate or not.
1745 if ((p->nr_cpus_allowed > 1) == (weight > 1))
1751 * The process used to be able to migrate OR it can now migrate
1754 if (!task_current(rq, p))
1755 dequeue_pushable_task(rq, p);
1756 BUG_ON(!rq->rt.rt_nr_migratory);
1757 rq->rt.rt_nr_migratory--;
1759 if (!task_current(rq, p))
1760 enqueue_pushable_task(rq, p);
1761 rq->rt.rt_nr_migratory++;
1764 update_rt_migration(&rq->rt);
1767 /* Assumes rq->lock is held */
1768 static void rq_online_rt(struct rq *rq)
1770 if (rq->rt.overloaded)
1771 rt_set_overload(rq);
1773 __enable_runtime(rq);
1775 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1778 /* Assumes rq->lock is held */
1779 static void rq_offline_rt(struct rq *rq)
1781 if (rq->rt.overloaded)
1782 rt_clear_overload(rq);
1784 __disable_runtime(rq);
1786 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1790 * When switch from the rt queue, we bring ourselves to a position
1791 * that we might want to pull RT tasks from other runqueues.
1793 static void switched_from_rt(struct rq *rq, struct task_struct *p)
1796 * If there are other RT tasks then we will reschedule
1797 * and the scheduling of the other RT tasks will handle
1798 * the balancing. But if we are the last RT task
1799 * we may need to handle the pulling of RT tasks
1802 if (!p->on_rq || rq->rt.rt_nr_running)
1805 if (pull_rt_task(rq))
1806 resched_task(rq->curr);
1809 void init_sched_rt_class(void)
1813 for_each_possible_cpu(i) {
1814 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
1815 GFP_KERNEL, cpu_to_node(i));
1818 #endif /* CONFIG_SMP */
1821 * When switching a task to RT, we may overload the runqueue
1822 * with RT tasks. In this case we try to push them off to
1825 static void switched_to_rt(struct rq *rq, struct task_struct *p)
1827 int check_resched = 1;
1830 * If we are already running, then there's nothing
1831 * that needs to be done. But if we are not running
1832 * we may need to preempt the current running task.
1833 * If that current running task is also an RT task
1834 * then see if we can move to another run queue.
1836 if (p->on_rq && rq->curr != p) {
1838 if (rq->rt.overloaded && push_rt_task(rq) &&
1839 /* Don't resched if we changed runqueues */
1842 #endif /* CONFIG_SMP */
1843 if (check_resched && p->prio < rq->curr->prio)
1844 resched_task(rq->curr);
1849 * Priority of the task has changed. This may cause
1850 * us to initiate a push or pull.
1853 prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
1858 if (rq->curr == p) {
1861 * If our priority decreases while running, we
1862 * may need to pull tasks to this runqueue.
1864 if (oldprio < p->prio)
1867 * If there's a higher priority task waiting to run
1868 * then reschedule. Note, the above pull_rt_task
1869 * can release the rq lock and p could migrate.
1870 * Only reschedule if p is still on the same runqueue.
1872 if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
1875 /* For UP simply resched on drop of prio */
1876 if (oldprio < p->prio)
1878 #endif /* CONFIG_SMP */
1881 * This task is not running, but if it is
1882 * greater than the current running task
1885 if (p->prio < rq->curr->prio)
1886 resched_task(rq->curr);
1890 static void watchdog(struct rq *rq, struct task_struct *p)
1892 unsigned long soft, hard;
1894 /* max may change after cur was read, this will be fixed next tick */
1895 soft = task_rlimit(p, RLIMIT_RTTIME);
1896 hard = task_rlimit_max(p, RLIMIT_RTTIME);
1898 if (soft != RLIM_INFINITY) {
1901 if (p->rt.watchdog_stamp != jiffies) {
1903 p->rt.watchdog_stamp = jiffies;
1906 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1907 if (p->rt.timeout > next)
1908 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
1912 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1914 struct sched_rt_entity *rt_se = &p->rt;
1921 * RR tasks need a special form of timeslice management.
1922 * FIFO tasks have no timeslices.
1924 if (p->policy != SCHED_RR)
1927 if (--p->rt.time_slice)
1930 p->rt.time_slice = sched_rr_timeslice;
1933 * Requeue to the end of queue if we (and all of our ancestors) are the
1934 * only element on the queue
1936 for_each_sched_rt_entity(rt_se) {
1937 if (rt_se->run_list.prev != rt_se->run_list.next) {
1938 requeue_task_rt(rq, p, 0);
1939 set_tsk_need_resched(p);
1945 static void set_curr_task_rt(struct rq *rq)
1947 struct task_struct *p = rq->curr;
1949 p->se.exec_start = rq_clock_task(rq);
1951 /* The running task is never eligible for pushing */
1952 dequeue_pushable_task(rq, p);
1955 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
1958 * Time slice is 0 for SCHED_FIFO tasks
1960 if (task->policy == SCHED_RR)
1961 return sched_rr_timeslice;
1966 const struct sched_class rt_sched_class = {
1967 .next = &fair_sched_class,
1968 .enqueue_task = enqueue_task_rt,
1969 .dequeue_task = dequeue_task_rt,
1970 .yield_task = yield_task_rt,
1972 .check_preempt_curr = check_preempt_curr_rt,
1974 .pick_next_task = pick_next_task_rt,
1975 .put_prev_task = put_prev_task_rt,
1978 .select_task_rq = select_task_rq_rt,
1980 .set_cpus_allowed = set_cpus_allowed_rt,
1981 .rq_online = rq_online_rt,
1982 .rq_offline = rq_offline_rt,
1983 .pre_schedule = pre_schedule_rt,
1984 .post_schedule = post_schedule_rt,
1985 .task_woken = task_woken_rt,
1986 .switched_from = switched_from_rt,
1989 .set_curr_task = set_curr_task_rt,
1990 .task_tick = task_tick_rt,
1992 .get_rr_interval = get_rr_interval_rt,
1994 .prio_changed = prio_changed_rt,
1995 .switched_to = switched_to_rt,
1998 #ifdef CONFIG_SCHED_DEBUG
1999 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
2001 void print_rt_stats(struct seq_file *m, int cpu)
2004 struct rt_rq *rt_rq;
2007 for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
2008 print_rt_rq(m, cpu, rt_rq);
2011 #endif /* CONFIG_SCHED_DEBUG */