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
250 * Matched by the barrier in pull_rt_task().
253 atomic_inc(&rq->rd->rto_count);
256 static inline void rt_clear_overload(struct rq *rq)
261 /* the order here really doesn't matter */
262 atomic_dec(&rq->rd->rto_count);
263 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
266 static void update_rt_migration(struct rt_rq *rt_rq)
268 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
269 if (!rt_rq->overloaded) {
270 rt_set_overload(rq_of_rt_rq(rt_rq));
271 rt_rq->overloaded = 1;
273 } else if (rt_rq->overloaded) {
274 rt_clear_overload(rq_of_rt_rq(rt_rq));
275 rt_rq->overloaded = 0;
279 static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
281 struct task_struct *p;
283 if (!rt_entity_is_task(rt_se))
286 p = rt_task_of(rt_se);
287 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
289 rt_rq->rt_nr_total++;
290 if (p->nr_cpus_allowed > 1)
291 rt_rq->rt_nr_migratory++;
293 update_rt_migration(rt_rq);
296 static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
298 struct task_struct *p;
300 if (!rt_entity_is_task(rt_se))
303 p = rt_task_of(rt_se);
304 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
306 rt_rq->rt_nr_total--;
307 if (p->nr_cpus_allowed > 1)
308 rt_rq->rt_nr_migratory--;
310 update_rt_migration(rt_rq);
313 static inline int has_pushable_tasks(struct rq *rq)
315 return !plist_head_empty(&rq->rt.pushable_tasks);
318 static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
320 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
321 plist_node_init(&p->pushable_tasks, p->prio);
322 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
324 /* Update the highest prio pushable task */
325 if (p->prio < rq->rt.highest_prio.next)
326 rq->rt.highest_prio.next = p->prio;
329 static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
331 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
333 /* Update the new highest prio pushable task */
334 if (has_pushable_tasks(rq)) {
335 p = plist_first_entry(&rq->rt.pushable_tasks,
336 struct task_struct, pushable_tasks);
337 rq->rt.highest_prio.next = p->prio;
339 rq->rt.highest_prio.next = MAX_RT_PRIO;
344 static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
348 static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
353 void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
358 void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
362 #endif /* CONFIG_SMP */
364 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
366 return !list_empty(&rt_se->run_list);
369 #ifdef CONFIG_RT_GROUP_SCHED
371 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
376 return rt_rq->rt_runtime;
379 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
381 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
384 typedef struct task_group *rt_rq_iter_t;
386 static inline struct task_group *next_task_group(struct task_group *tg)
389 tg = list_entry_rcu(tg->list.next,
390 typeof(struct task_group), list);
391 } while (&tg->list != &task_groups && task_group_is_autogroup(tg));
393 if (&tg->list == &task_groups)
399 #define for_each_rt_rq(rt_rq, iter, rq) \
400 for (iter = container_of(&task_groups, typeof(*iter), list); \
401 (iter = next_task_group(iter)) && \
402 (rt_rq = iter->rt_rq[cpu_of(rq)]);)
404 #define for_each_sched_rt_entity(rt_se) \
405 for (; rt_se; rt_se = rt_se->parent)
407 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
412 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
413 static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
415 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
417 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
418 struct sched_rt_entity *rt_se;
420 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
422 rt_se = rt_rq->tg->rt_se[cpu];
424 if (rt_rq->rt_nr_running) {
425 if (rt_se && !on_rt_rq(rt_se))
426 enqueue_rt_entity(rt_se, false);
427 if (rt_rq->highest_prio.curr < curr->prio)
432 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
434 struct sched_rt_entity *rt_se;
435 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
437 rt_se = rt_rq->tg->rt_se[cpu];
439 if (rt_se && on_rt_rq(rt_se))
440 dequeue_rt_entity(rt_se);
443 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
445 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
448 static int rt_se_boosted(struct sched_rt_entity *rt_se)
450 struct rt_rq *rt_rq = group_rt_rq(rt_se);
451 struct task_struct *p;
454 return !!rt_rq->rt_nr_boosted;
456 p = rt_task_of(rt_se);
457 return p->prio != p->normal_prio;
461 static inline const struct cpumask *sched_rt_period_mask(void)
463 return this_rq()->rd->span;
466 static inline const struct cpumask *sched_rt_period_mask(void)
468 return cpu_online_mask;
473 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
475 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
478 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
480 return &rt_rq->tg->rt_bandwidth;
483 #else /* !CONFIG_RT_GROUP_SCHED */
485 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
487 return rt_rq->rt_runtime;
490 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
492 return ktime_to_ns(def_rt_bandwidth.rt_period);
495 typedef struct rt_rq *rt_rq_iter_t;
497 #define for_each_rt_rq(rt_rq, iter, rq) \
498 for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
500 #define for_each_sched_rt_entity(rt_se) \
501 for (; rt_se; rt_se = NULL)
503 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
508 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
510 if (rt_rq->rt_nr_running)
511 resched_task(rq_of_rt_rq(rt_rq)->curr);
514 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
518 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
520 return rt_rq->rt_throttled;
523 static inline const struct cpumask *sched_rt_period_mask(void)
525 return cpu_online_mask;
529 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
531 return &cpu_rq(cpu)->rt;
534 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
536 return &def_rt_bandwidth;
539 #endif /* CONFIG_RT_GROUP_SCHED */
543 * We ran out of runtime, see if we can borrow some from our neighbours.
545 static int do_balance_runtime(struct rt_rq *rt_rq)
547 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
548 struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;
549 int i, weight, more = 0;
552 weight = cpumask_weight(rd->span);
554 raw_spin_lock(&rt_b->rt_runtime_lock);
555 rt_period = ktime_to_ns(rt_b->rt_period);
556 for_each_cpu(i, rd->span) {
557 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
563 raw_spin_lock(&iter->rt_runtime_lock);
565 * Either all rqs have inf runtime and there's nothing to steal
566 * or __disable_runtime() below sets a specific rq to inf to
567 * indicate its been disabled and disalow stealing.
569 if (iter->rt_runtime == RUNTIME_INF)
573 * From runqueues with spare time, take 1/n part of their
574 * spare time, but no more than our period.
576 diff = iter->rt_runtime - iter->rt_time;
578 diff = div_u64((u64)diff, weight);
579 if (rt_rq->rt_runtime + diff > rt_period)
580 diff = rt_period - rt_rq->rt_runtime;
581 iter->rt_runtime -= diff;
582 rt_rq->rt_runtime += diff;
584 if (rt_rq->rt_runtime == rt_period) {
585 raw_spin_unlock(&iter->rt_runtime_lock);
590 raw_spin_unlock(&iter->rt_runtime_lock);
592 raw_spin_unlock(&rt_b->rt_runtime_lock);
598 * Ensure this RQ takes back all the runtime it lend to its neighbours.
600 static void __disable_runtime(struct rq *rq)
602 struct root_domain *rd = rq->rd;
606 if (unlikely(!scheduler_running))
609 for_each_rt_rq(rt_rq, iter, rq) {
610 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
614 raw_spin_lock(&rt_b->rt_runtime_lock);
615 raw_spin_lock(&rt_rq->rt_runtime_lock);
617 * Either we're all inf and nobody needs to borrow, or we're
618 * already disabled and thus have nothing to do, or we have
619 * exactly the right amount of runtime to take out.
621 if (rt_rq->rt_runtime == RUNTIME_INF ||
622 rt_rq->rt_runtime == rt_b->rt_runtime)
624 raw_spin_unlock(&rt_rq->rt_runtime_lock);
627 * Calculate the difference between what we started out with
628 * and what we current have, that's the amount of runtime
629 * we lend and now have to reclaim.
631 want = rt_b->rt_runtime - rt_rq->rt_runtime;
634 * Greedy reclaim, take back as much as we can.
636 for_each_cpu(i, rd->span) {
637 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
641 * Can't reclaim from ourselves or disabled runqueues.
643 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
646 raw_spin_lock(&iter->rt_runtime_lock);
648 diff = min_t(s64, iter->rt_runtime, want);
649 iter->rt_runtime -= diff;
652 iter->rt_runtime -= want;
655 raw_spin_unlock(&iter->rt_runtime_lock);
661 raw_spin_lock(&rt_rq->rt_runtime_lock);
663 * We cannot be left wanting - that would mean some runtime
664 * leaked out of the system.
669 * Disable all the borrow logic by pretending we have inf
670 * runtime - in which case borrowing doesn't make sense.
672 rt_rq->rt_runtime = RUNTIME_INF;
673 rt_rq->rt_throttled = 0;
674 raw_spin_unlock(&rt_rq->rt_runtime_lock);
675 raw_spin_unlock(&rt_b->rt_runtime_lock);
679 static void __enable_runtime(struct rq *rq)
684 if (unlikely(!scheduler_running))
688 * Reset each runqueue's bandwidth settings
690 for_each_rt_rq(rt_rq, iter, rq) {
691 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
693 raw_spin_lock(&rt_b->rt_runtime_lock);
694 raw_spin_lock(&rt_rq->rt_runtime_lock);
695 rt_rq->rt_runtime = rt_b->rt_runtime;
697 rt_rq->rt_throttled = 0;
698 raw_spin_unlock(&rt_rq->rt_runtime_lock);
699 raw_spin_unlock(&rt_b->rt_runtime_lock);
703 static int balance_runtime(struct rt_rq *rt_rq)
707 if (!sched_feat(RT_RUNTIME_SHARE))
710 if (rt_rq->rt_time > rt_rq->rt_runtime) {
711 raw_spin_unlock(&rt_rq->rt_runtime_lock);
712 more = do_balance_runtime(rt_rq);
713 raw_spin_lock(&rt_rq->rt_runtime_lock);
718 #else /* !CONFIG_SMP */
719 static inline int balance_runtime(struct rt_rq *rt_rq)
723 #endif /* CONFIG_SMP */
725 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
727 int i, idle = 1, throttled = 0;
728 const struct cpumask *span;
730 span = sched_rt_period_mask();
731 #ifdef CONFIG_RT_GROUP_SCHED
733 * FIXME: isolated CPUs should really leave the root task group,
734 * whether they are isolcpus or were isolated via cpusets, lest
735 * the timer run on a CPU which does not service all runqueues,
736 * potentially leaving other CPUs indefinitely throttled. If
737 * isolation is really required, the user will turn the throttle
738 * off to kill the perturbations it causes anyway. Meanwhile,
739 * this maintains functionality for boot and/or troubleshooting.
741 if (rt_b == &root_task_group.rt_bandwidth)
742 span = cpu_online_mask;
744 for_each_cpu(i, span) {
746 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
747 struct rq *rq = rq_of_rt_rq(rt_rq);
749 raw_spin_lock(&rq->lock);
750 if (rt_rq->rt_time) {
753 raw_spin_lock(&rt_rq->rt_runtime_lock);
754 if (rt_rq->rt_throttled)
755 balance_runtime(rt_rq);
756 runtime = rt_rq->rt_runtime;
757 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
758 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
759 rt_rq->rt_throttled = 0;
763 * Force a clock update if the CPU was idle,
764 * lest wakeup -> unthrottle time accumulate.
766 if (rt_rq->rt_nr_running && rq->curr == rq->idle)
767 rq->skip_clock_update = -1;
769 if (rt_rq->rt_time || rt_rq->rt_nr_running)
771 raw_spin_unlock(&rt_rq->rt_runtime_lock);
772 } else if (rt_rq->rt_nr_running) {
774 if (!rt_rq_throttled(rt_rq))
777 if (rt_rq->rt_throttled)
781 sched_rt_rq_enqueue(rt_rq);
782 raw_spin_unlock(&rq->lock);
785 if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
791 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
793 #ifdef CONFIG_RT_GROUP_SCHED
794 struct rt_rq *rt_rq = group_rt_rq(rt_se);
797 return rt_rq->highest_prio.curr;
800 return rt_task_of(rt_se)->prio;
803 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
805 u64 runtime = sched_rt_runtime(rt_rq);
807 if (rt_rq->rt_throttled)
808 return rt_rq_throttled(rt_rq);
810 if (runtime >= sched_rt_period(rt_rq))
813 balance_runtime(rt_rq);
814 runtime = sched_rt_runtime(rt_rq);
815 if (runtime == RUNTIME_INF)
818 if (rt_rq->rt_time > runtime) {
819 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
822 * Don't actually throttle groups that have no runtime assigned
823 * but accrue some time due to boosting.
825 if (likely(rt_b->rt_runtime)) {
826 static bool once = false;
828 rt_rq->rt_throttled = 1;
832 printk_sched("sched: RT throttling activated\n");
836 * In case we did anyway, make it go away,
837 * replenishment is a joke, since it will replenish us
843 if (rt_rq_throttled(rt_rq)) {
844 sched_rt_rq_dequeue(rt_rq);
853 * Update the current task's runtime statistics. Skip current tasks that
854 * are not in our scheduling class.
856 static void update_curr_rt(struct rq *rq)
858 struct task_struct *curr = rq->curr;
859 struct sched_rt_entity *rt_se = &curr->rt;
860 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
863 if (curr->sched_class != &rt_sched_class)
866 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
867 if (unlikely((s64)delta_exec <= 0))
870 schedstat_set(curr->se.statistics.exec_max,
871 max(curr->se.statistics.exec_max, delta_exec));
873 curr->se.sum_exec_runtime += delta_exec;
874 account_group_exec_runtime(curr, delta_exec);
876 curr->se.exec_start = rq_clock_task(rq);
877 cpuacct_charge(curr, delta_exec);
879 sched_rt_avg_update(rq, delta_exec);
881 if (!rt_bandwidth_enabled())
884 for_each_sched_rt_entity(rt_se) {
885 rt_rq = rt_rq_of_se(rt_se);
887 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
888 raw_spin_lock(&rt_rq->rt_runtime_lock);
889 rt_rq->rt_time += delta_exec;
890 if (sched_rt_runtime_exceeded(rt_rq))
892 raw_spin_unlock(&rt_rq->rt_runtime_lock);
897 #if defined CONFIG_SMP
900 inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
902 struct rq *rq = rq_of_rt_rq(rt_rq);
904 #ifdef CONFIG_RT_GROUP_SCHED
906 * Change rq's cpupri only if rt_rq is the top queue.
908 if (&rq->rt != rt_rq)
911 if (rq->online && prio < prev_prio)
912 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
916 dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
918 struct rq *rq = rq_of_rt_rq(rt_rq);
920 #ifdef CONFIG_RT_GROUP_SCHED
922 * Change rq's cpupri only if rt_rq is the top queue.
924 if (&rq->rt != rt_rq)
927 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
928 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
931 #else /* CONFIG_SMP */
934 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
936 void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
938 #endif /* CONFIG_SMP */
940 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
942 inc_rt_prio(struct rt_rq *rt_rq, int prio)
944 int prev_prio = rt_rq->highest_prio.curr;
946 if (prio < prev_prio)
947 rt_rq->highest_prio.curr = prio;
949 inc_rt_prio_smp(rt_rq, prio, prev_prio);
953 dec_rt_prio(struct rt_rq *rt_rq, int prio)
955 int prev_prio = rt_rq->highest_prio.curr;
957 if (rt_rq->rt_nr_running) {
959 WARN_ON(prio < prev_prio);
962 * This may have been our highest task, and therefore
963 * we may have some recomputation to do
965 if (prio == prev_prio) {
966 struct rt_prio_array *array = &rt_rq->active;
968 rt_rq->highest_prio.curr =
969 sched_find_first_bit(array->bitmap);
973 rt_rq->highest_prio.curr = MAX_RT_PRIO;
975 dec_rt_prio_smp(rt_rq, prio, prev_prio);
980 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
981 static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
983 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
985 #ifdef CONFIG_RT_GROUP_SCHED
988 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
990 if (rt_se_boosted(rt_se))
991 rt_rq->rt_nr_boosted++;
994 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
998 dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1000 if (rt_se_boosted(rt_se))
1001 rt_rq->rt_nr_boosted--;
1003 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
1006 #else /* CONFIG_RT_GROUP_SCHED */
1009 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1011 start_rt_bandwidth(&def_rt_bandwidth);
1015 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1017 #endif /* CONFIG_RT_GROUP_SCHED */
1020 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1022 int prio = rt_se_prio(rt_se);
1024 WARN_ON(!rt_prio(prio));
1025 rt_rq->rt_nr_running++;
1027 inc_rt_prio(rt_rq, prio);
1028 inc_rt_migration(rt_se, rt_rq);
1029 inc_rt_group(rt_se, rt_rq);
1033 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1035 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
1036 WARN_ON(!rt_rq->rt_nr_running);
1037 rt_rq->rt_nr_running--;
1039 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
1040 dec_rt_migration(rt_se, rt_rq);
1041 dec_rt_group(rt_se, rt_rq);
1044 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1046 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1047 struct rt_prio_array *array = &rt_rq->active;
1048 struct rt_rq *group_rq = group_rt_rq(rt_se);
1049 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1052 * Don't enqueue the group if its throttled, or when empty.
1053 * The latter is a consequence of the former when a child group
1054 * get throttled and the current group doesn't have any other
1057 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
1061 list_add(&rt_se->run_list, queue);
1063 list_add_tail(&rt_se->run_list, queue);
1064 __set_bit(rt_se_prio(rt_se), array->bitmap);
1066 inc_rt_tasks(rt_se, rt_rq);
1069 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
1071 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1072 struct rt_prio_array *array = &rt_rq->active;
1074 list_del_init(&rt_se->run_list);
1075 if (list_empty(array->queue + rt_se_prio(rt_se)))
1076 __clear_bit(rt_se_prio(rt_se), array->bitmap);
1078 dec_rt_tasks(rt_se, rt_rq);
1082 * Because the prio of an upper entry depends on the lower
1083 * entries, we must remove entries top - down.
1085 static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
1087 struct sched_rt_entity *back = NULL;
1089 for_each_sched_rt_entity(rt_se) {
1094 for (rt_se = back; rt_se; rt_se = rt_se->back) {
1095 if (on_rt_rq(rt_se))
1096 __dequeue_rt_entity(rt_se);
1100 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1102 dequeue_rt_stack(rt_se);
1103 for_each_sched_rt_entity(rt_se)
1104 __enqueue_rt_entity(rt_se, head);
1107 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
1109 dequeue_rt_stack(rt_se);
1111 for_each_sched_rt_entity(rt_se) {
1112 struct rt_rq *rt_rq = group_rt_rq(rt_se);
1114 if (rt_rq && rt_rq->rt_nr_running)
1115 __enqueue_rt_entity(rt_se, false);
1120 * Adding/removing a task to/from a priority array:
1123 enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1125 struct sched_rt_entity *rt_se = &p->rt;
1127 if (flags & ENQUEUE_WAKEUP)
1130 enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
1132 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1133 enqueue_pushable_task(rq, p);
1138 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1140 struct sched_rt_entity *rt_se = &p->rt;
1143 dequeue_rt_entity(rt_se);
1145 dequeue_pushable_task(rq, p);
1151 * Put task to the head or the end of the run list without the overhead of
1152 * dequeue followed by enqueue.
1155 requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
1157 if (on_rt_rq(rt_se)) {
1158 struct rt_prio_array *array = &rt_rq->active;
1159 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1162 list_move(&rt_se->run_list, queue);
1164 list_move_tail(&rt_se->run_list, queue);
1168 static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
1170 struct sched_rt_entity *rt_se = &p->rt;
1171 struct rt_rq *rt_rq;
1173 for_each_sched_rt_entity(rt_se) {
1174 rt_rq = rt_rq_of_se(rt_se);
1175 requeue_rt_entity(rt_rq, rt_se, head);
1179 static void yield_task_rt(struct rq *rq)
1181 requeue_task_rt(rq, rq->curr, 0);
1185 static int find_lowest_rq(struct task_struct *task);
1188 select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
1190 struct task_struct *curr;
1193 if (p->nr_cpus_allowed == 1)
1196 /* For anything but wake ups, just return the task_cpu */
1197 if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
1203 curr = ACCESS_ONCE(rq->curr); /* unlocked access */
1206 * If the current task on @p's runqueue is an RT task, then
1207 * try to see if we can wake this RT task up on another
1208 * runqueue. Otherwise simply start this RT task
1209 * on its current runqueue.
1211 * We want to avoid overloading runqueues. If the woken
1212 * task is a higher priority, then it will stay on this CPU
1213 * and the lower prio task should be moved to another CPU.
1214 * Even though this will probably make the lower prio task
1215 * lose its cache, we do not want to bounce a higher task
1216 * around just because it gave up its CPU, perhaps for a
1219 * For equal prio tasks, we just let the scheduler sort it out.
1221 * Otherwise, just let it ride on the affined RQ and the
1222 * post-schedule router will push the preempted task away
1224 * This test is optimistic, if we get it wrong the load-balancer
1225 * will have to sort it out.
1227 if (curr && unlikely(rt_task(curr)) &&
1228 (curr->nr_cpus_allowed < 2 ||
1229 curr->prio <= p->prio)) {
1230 int target = find_lowest_rq(p);
1241 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1243 if (rq->curr->nr_cpus_allowed == 1)
1246 if (p->nr_cpus_allowed != 1
1247 && cpupri_find(&rq->rd->cpupri, p, NULL))
1250 if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1254 * There appears to be other cpus that can accept
1255 * current and none to run 'p', so lets reschedule
1256 * to try and push current away:
1258 requeue_task_rt(rq, p, 1);
1259 resched_task(rq->curr);
1262 #endif /* CONFIG_SMP */
1265 * Preempt the current task with a newly woken task if needed:
1267 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1269 if (p->prio < rq->curr->prio) {
1270 resched_task(rq->curr);
1278 * - the newly woken task is of equal priority to the current task
1279 * - the newly woken task is non-migratable while current is migratable
1280 * - current will be preempted on the next reschedule
1282 * we should check to see if current can readily move to a different
1283 * cpu. If so, we will reschedule to allow the push logic to try
1284 * to move current somewhere else, making room for our non-migratable
1287 if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1288 check_preempt_equal_prio(rq, p);
1292 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1293 struct rt_rq *rt_rq)
1295 struct rt_prio_array *array = &rt_rq->active;
1296 struct sched_rt_entity *next = NULL;
1297 struct list_head *queue;
1300 idx = sched_find_first_bit(array->bitmap);
1301 BUG_ON(idx >= MAX_RT_PRIO);
1303 queue = array->queue + idx;
1304 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1309 static struct task_struct *_pick_next_task_rt(struct rq *rq)
1311 struct sched_rt_entity *rt_se;
1312 struct task_struct *p;
1313 struct rt_rq *rt_rq;
1317 if (!rt_rq->rt_nr_running)
1320 if (rt_rq_throttled(rt_rq))
1324 rt_se = pick_next_rt_entity(rq, rt_rq);
1326 rt_rq = group_rt_rq(rt_se);
1329 p = rt_task_of(rt_se);
1330 p->se.exec_start = rq_clock_task(rq);
1335 static struct task_struct *pick_next_task_rt(struct rq *rq)
1337 struct task_struct *p = _pick_next_task_rt(rq);
1339 /* The running task is never eligible for pushing */
1341 dequeue_pushable_task(rq, p);
1345 * We detect this state here so that we can avoid taking the RQ
1346 * lock again later if there is no need to push
1348 rq->post_schedule = has_pushable_tasks(rq);
1354 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1359 * The previous task needs to be made eligible for pushing
1360 * if it is still active
1362 if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
1363 enqueue_pushable_task(rq, p);
1368 /* Only try algorithms three times */
1369 #define RT_MAX_TRIES 3
1371 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1373 if (!task_running(rq, p) &&
1374 cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
1380 * Return the highest pushable rq's task, which is suitable to be executed
1381 * on the cpu, NULL otherwise
1383 static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
1385 struct plist_head *head = &rq->rt.pushable_tasks;
1386 struct task_struct *p;
1388 if (!has_pushable_tasks(rq))
1391 plist_for_each_entry(p, head, pushable_tasks) {
1392 if (pick_rt_task(rq, p, cpu))
1399 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1401 static int find_lowest_rq(struct task_struct *task)
1403 struct sched_domain *sd;
1404 struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
1405 int this_cpu = smp_processor_id();
1406 int cpu = task_cpu(task);
1408 /* Make sure the mask is initialized first */
1409 if (unlikely(!lowest_mask))
1412 if (task->nr_cpus_allowed == 1)
1413 return -1; /* No other targets possible */
1415 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1416 return -1; /* No targets found */
1419 * At this point we have built a mask of cpus representing the
1420 * lowest priority tasks in the system. Now we want to elect
1421 * the best one based on our affinity and topology.
1423 * We prioritize the last cpu that the task executed on since
1424 * it is most likely cache-hot in that location.
1426 if (cpumask_test_cpu(cpu, lowest_mask))
1430 * Otherwise, we consult the sched_domains span maps to figure
1431 * out which cpu is logically closest to our hot cache data.
1433 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1434 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1437 for_each_domain(cpu, sd) {
1438 if (sd->flags & SD_WAKE_AFFINE) {
1442 * "this_cpu" is cheaper to preempt than a
1445 if (this_cpu != -1 &&
1446 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1451 best_cpu = cpumask_first_and(lowest_mask,
1452 sched_domain_span(sd));
1453 if (best_cpu < nr_cpu_ids) {
1462 * And finally, if there were no matches within the domains
1463 * just give the caller *something* to work with from the compatible
1469 cpu = cpumask_any(lowest_mask);
1470 if (cpu < nr_cpu_ids)
1475 /* Will lock the rq it finds */
1476 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1478 struct rq *lowest_rq = NULL;
1482 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1483 cpu = find_lowest_rq(task);
1485 if ((cpu == -1) || (cpu == rq->cpu))
1488 lowest_rq = cpu_rq(cpu);
1490 /* if the prio of this runqueue changed, try again */
1491 if (double_lock_balance(rq, lowest_rq)) {
1493 * We had to unlock the run queue. In
1494 * the mean time, task could have
1495 * migrated already or had its affinity changed.
1496 * Also make sure that it wasn't scheduled on its rq.
1498 if (unlikely(task_rq(task) != rq ||
1499 !cpumask_test_cpu(lowest_rq->cpu,
1500 tsk_cpus_allowed(task)) ||
1501 task_running(rq, task) ||
1504 double_unlock_balance(rq, lowest_rq);
1510 /* If this rq is still suitable use it. */
1511 if (lowest_rq->rt.highest_prio.curr > task->prio)
1515 double_unlock_balance(rq, lowest_rq);
1522 static struct task_struct *pick_next_pushable_task(struct rq *rq)
1524 struct task_struct *p;
1526 if (!has_pushable_tasks(rq))
1529 p = plist_first_entry(&rq->rt.pushable_tasks,
1530 struct task_struct, pushable_tasks);
1532 BUG_ON(rq->cpu != task_cpu(p));
1533 BUG_ON(task_current(rq, p));
1534 BUG_ON(p->nr_cpus_allowed <= 1);
1537 BUG_ON(!rt_task(p));
1543 * If the current CPU has more than one RT task, see if the non
1544 * running task can migrate over to a CPU that is running a task
1545 * of lesser priority.
1547 static int push_rt_task(struct rq *rq)
1549 struct task_struct *next_task;
1550 struct rq *lowest_rq;
1553 if (!rq->rt.overloaded)
1556 next_task = pick_next_pushable_task(rq);
1561 if (unlikely(next_task == rq->curr)) {
1567 * It's possible that the next_task slipped in of
1568 * higher priority than current. If that's the case
1569 * just reschedule current.
1571 if (unlikely(next_task->prio < rq->curr->prio)) {
1572 resched_task(rq->curr);
1576 /* We might release rq lock */
1577 get_task_struct(next_task);
1579 /* find_lock_lowest_rq locks the rq if found */
1580 lowest_rq = find_lock_lowest_rq(next_task, rq);
1582 struct task_struct *task;
1584 * find_lock_lowest_rq releases rq->lock
1585 * so it is possible that next_task has migrated.
1587 * We need to make sure that the task is still on the same
1588 * run-queue and is also still the next task eligible for
1591 task = pick_next_pushable_task(rq);
1592 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1594 * The task hasn't migrated, and is still the next
1595 * eligible task, but we failed to find a run-queue
1596 * to push it to. Do not retry in this case, since
1597 * other cpus will pull from us when ready.
1603 /* No more tasks, just exit */
1607 * Something has shifted, try again.
1609 put_task_struct(next_task);
1614 deactivate_task(rq, next_task, 0);
1615 set_task_cpu(next_task, lowest_rq->cpu);
1616 activate_task(lowest_rq, next_task, 0);
1619 resched_task(lowest_rq->curr);
1621 double_unlock_balance(rq, lowest_rq);
1624 put_task_struct(next_task);
1629 static void push_rt_tasks(struct rq *rq)
1631 /* push_rt_task will return true if it moved an RT */
1632 while (push_rt_task(rq))
1636 static int pull_rt_task(struct rq *this_rq)
1638 int this_cpu = this_rq->cpu, ret = 0, cpu;
1639 struct task_struct *p;
1642 if (likely(!rt_overloaded(this_rq)))
1646 * Match the barrier from rt_set_overloaded; this guarantees that if we
1647 * see overloaded we must also see the rto_mask bit.
1651 for_each_cpu(cpu, this_rq->rd->rto_mask) {
1652 if (this_cpu == cpu)
1655 src_rq = cpu_rq(cpu);
1658 * Don't bother taking the src_rq->lock if the next highest
1659 * task is known to be lower-priority than our current task.
1660 * This may look racy, but if this value is about to go
1661 * logically higher, the src_rq will push this task away.
1662 * And if its going logically lower, we do not care
1664 if (src_rq->rt.highest_prio.next >=
1665 this_rq->rt.highest_prio.curr)
1669 * We can potentially drop this_rq's lock in
1670 * double_lock_balance, and another CPU could
1673 double_lock_balance(this_rq, src_rq);
1676 * We can pull only a task, which is pushable
1677 * on its rq, and no others.
1679 p = pick_highest_pushable_task(src_rq, this_cpu);
1682 * Do we have an RT task that preempts
1683 * the to-be-scheduled task?
1685 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
1686 WARN_ON(p == src_rq->curr);
1690 * There's a chance that p is higher in priority
1691 * than what's currently running on its cpu.
1692 * This is just that p is wakeing up and hasn't
1693 * had a chance to schedule. We only pull
1694 * p if it is lower in priority than the
1695 * current task on the run queue
1697 if (p->prio < src_rq->curr->prio)
1702 deactivate_task(src_rq, p, 0);
1703 set_task_cpu(p, this_cpu);
1704 activate_task(this_rq, p, 0);
1706 * We continue with the search, just in
1707 * case there's an even higher prio task
1708 * in another runqueue. (low likelihood
1713 double_unlock_balance(this_rq, src_rq);
1719 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1721 /* Try to pull RT tasks here if we lower this rq's prio */
1722 if (rq->rt.highest_prio.curr > prev->prio)
1726 static void post_schedule_rt(struct rq *rq)
1732 * If we are not running and we are not going to reschedule soon, we should
1733 * try to push tasks away now
1735 static void task_woken_rt(struct rq *rq, struct task_struct *p)
1737 if (!task_running(rq, p) &&
1738 !test_tsk_need_resched(rq->curr) &&
1739 has_pushable_tasks(rq) &&
1740 p->nr_cpus_allowed > 1 &&
1741 (dl_task(rq->curr) || rt_task(rq->curr)) &&
1742 (rq->curr->nr_cpus_allowed < 2 ||
1743 rq->curr->prio <= p->prio))
1747 static void set_cpus_allowed_rt(struct task_struct *p,
1748 const struct cpumask *new_mask)
1753 BUG_ON(!rt_task(p));
1758 weight = cpumask_weight(new_mask);
1761 * Only update if the process changes its state from whether it
1762 * can migrate or not.
1764 if ((p->nr_cpus_allowed > 1) == (weight > 1))
1770 * The process used to be able to migrate OR it can now migrate
1773 if (!task_current(rq, p))
1774 dequeue_pushable_task(rq, p);
1775 BUG_ON(!rq->rt.rt_nr_migratory);
1776 rq->rt.rt_nr_migratory--;
1778 if (!task_current(rq, p))
1779 enqueue_pushable_task(rq, p);
1780 rq->rt.rt_nr_migratory++;
1783 update_rt_migration(&rq->rt);
1786 /* Assumes rq->lock is held */
1787 static void rq_online_rt(struct rq *rq)
1789 if (rq->rt.overloaded)
1790 rt_set_overload(rq);
1792 __enable_runtime(rq);
1794 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1797 /* Assumes rq->lock is held */
1798 static void rq_offline_rt(struct rq *rq)
1800 if (rq->rt.overloaded)
1801 rt_clear_overload(rq);
1803 __disable_runtime(rq);
1805 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1809 * When switch from the rt queue, we bring ourselves to a position
1810 * that we might want to pull RT tasks from other runqueues.
1812 static void switched_from_rt(struct rq *rq, struct task_struct *p)
1815 * If there are other RT tasks then we will reschedule
1816 * and the scheduling of the other RT tasks will handle
1817 * the balancing. But if we are the last RT task
1818 * we may need to handle the pulling of RT tasks
1821 if (!p->on_rq || rq->rt.rt_nr_running)
1824 if (pull_rt_task(rq))
1825 resched_task(rq->curr);
1828 void init_sched_rt_class(void)
1832 for_each_possible_cpu(i) {
1833 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
1834 GFP_KERNEL, cpu_to_node(i));
1837 #endif /* CONFIG_SMP */
1840 * When switching a task to RT, we may overload the runqueue
1841 * with RT tasks. In this case we try to push them off to
1844 static void switched_to_rt(struct rq *rq, struct task_struct *p)
1846 int check_resched = 1;
1849 * If we are already running, then there's nothing
1850 * that needs to be done. But if we are not running
1851 * we may need to preempt the current running task.
1852 * If that current running task is also an RT task
1853 * then see if we can move to another run queue.
1855 if (p->on_rq && rq->curr != p) {
1857 if (rq->rt.overloaded && push_rt_task(rq) &&
1858 /* Don't resched if we changed runqueues */
1861 #endif /* CONFIG_SMP */
1862 if (check_resched && p->prio < rq->curr->prio)
1863 resched_task(rq->curr);
1868 * Priority of the task has changed. This may cause
1869 * us to initiate a push or pull.
1872 prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
1877 if (rq->curr == p) {
1880 * If our priority decreases while running, we
1881 * may need to pull tasks to this runqueue.
1883 if (oldprio < p->prio)
1886 * If there's a higher priority task waiting to run
1887 * then reschedule. Note, the above pull_rt_task
1888 * can release the rq lock and p could migrate.
1889 * Only reschedule if p is still on the same runqueue.
1891 if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
1894 /* For UP simply resched on drop of prio */
1895 if (oldprio < p->prio)
1897 #endif /* CONFIG_SMP */
1900 * This task is not running, but if it is
1901 * greater than the current running task
1904 if (p->prio < rq->curr->prio)
1905 resched_task(rq->curr);
1909 static void watchdog(struct rq *rq, struct task_struct *p)
1911 unsigned long soft, hard;
1913 /* max may change after cur was read, this will be fixed next tick */
1914 soft = task_rlimit(p, RLIMIT_RTTIME);
1915 hard = task_rlimit_max(p, RLIMIT_RTTIME);
1917 if (soft != RLIM_INFINITY) {
1920 if (p->rt.watchdog_stamp != jiffies) {
1922 p->rt.watchdog_stamp = jiffies;
1925 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1926 if (p->rt.timeout > next)
1927 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
1931 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1933 struct sched_rt_entity *rt_se = &p->rt;
1940 * RR tasks need a special form of timeslice management.
1941 * FIFO tasks have no timeslices.
1943 if (p->policy != SCHED_RR)
1946 if (--p->rt.time_slice)
1949 p->rt.time_slice = sched_rr_timeslice;
1952 * Requeue to the end of queue if we (and all of our ancestors) are not
1953 * the only element on the queue
1955 for_each_sched_rt_entity(rt_se) {
1956 if (rt_se->run_list.prev != rt_se->run_list.next) {
1957 requeue_task_rt(rq, p, 0);
1958 set_tsk_need_resched(p);
1964 static void set_curr_task_rt(struct rq *rq)
1966 struct task_struct *p = rq->curr;
1968 p->se.exec_start = rq_clock_task(rq);
1970 /* The running task is never eligible for pushing */
1971 dequeue_pushable_task(rq, p);
1974 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
1977 * Time slice is 0 for SCHED_FIFO tasks
1979 if (task->policy == SCHED_RR)
1980 return sched_rr_timeslice;
1985 const struct sched_class rt_sched_class = {
1986 .next = &fair_sched_class,
1987 .enqueue_task = enqueue_task_rt,
1988 .dequeue_task = dequeue_task_rt,
1989 .yield_task = yield_task_rt,
1991 .check_preempt_curr = check_preempt_curr_rt,
1993 .pick_next_task = pick_next_task_rt,
1994 .put_prev_task = put_prev_task_rt,
1997 .select_task_rq = select_task_rq_rt,
1999 .set_cpus_allowed = set_cpus_allowed_rt,
2000 .rq_online = rq_online_rt,
2001 .rq_offline = rq_offline_rt,
2002 .pre_schedule = pre_schedule_rt,
2003 .post_schedule = post_schedule_rt,
2004 .task_woken = task_woken_rt,
2005 .switched_from = switched_from_rt,
2008 .set_curr_task = set_curr_task_rt,
2009 .task_tick = task_tick_rt,
2011 .get_rr_interval = get_rr_interval_rt,
2013 .prio_changed = prio_changed_rt,
2014 .switched_to = switched_to_rt,
2017 #ifdef CONFIG_SCHED_DEBUG
2018 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
2020 void print_rt_stats(struct seq_file *m, int cpu)
2023 struct rt_rq *rt_rq;
2026 for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
2027 print_rt_rq(m, cpu, rt_rq);
2030 #endif /* CONFIG_SCHED_DEBUG */