2 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
8 static inline int rt_overloaded(struct rq *rq)
10 return atomic_read(&rq->rd->rto_count);
13 static inline void rt_set_overload(struct rq *rq)
18 cpu_set(rq->cpu, rq->rd->rto_mask);
20 * Make sure the mask is visible before we set
21 * the overload count. That is checked to determine
22 * if we should look at the mask. It would be a shame
23 * if we looked at the mask, but the mask was not
27 atomic_inc(&rq->rd->rto_count);
30 static inline void rt_clear_overload(struct rq *rq)
35 /* the order here really doesn't matter */
36 atomic_dec(&rq->rd->rto_count);
37 cpu_clear(rq->cpu, rq->rd->rto_mask);
40 static void update_rt_migration(struct rq *rq)
42 if (rq->rt.rt_nr_migratory && (rq->rt.rt_nr_running > 1)) {
43 if (!rq->rt.overloaded) {
45 rq->rt.overloaded = 1;
47 } else if (rq->rt.overloaded) {
48 rt_clear_overload(rq);
49 rq->rt.overloaded = 0;
52 #endif /* CONFIG_SMP */
54 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
56 return container_of(rt_se, struct task_struct, rt);
59 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
61 return !list_empty(&rt_se->run_list);
64 #ifdef CONFIG_RT_GROUP_SCHED
66 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
71 return rt_rq->rt_runtime;
74 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
76 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
79 #define for_each_leaf_rt_rq(rt_rq, rq) \
80 list_for_each_entry(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
82 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
87 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
92 #define for_each_sched_rt_entity(rt_se) \
93 for (; rt_se; rt_se = rt_se->parent)
95 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
100 static void enqueue_rt_entity(struct sched_rt_entity *rt_se);
101 static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
103 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
105 struct sched_rt_entity *rt_se = rt_rq->rt_se;
107 if (rt_se && !on_rt_rq(rt_se) && rt_rq->rt_nr_running) {
108 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
110 enqueue_rt_entity(rt_se);
111 if (rt_rq->highest_prio < curr->prio)
116 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
118 struct sched_rt_entity *rt_se = rt_rq->rt_se;
120 if (rt_se && on_rt_rq(rt_se))
121 dequeue_rt_entity(rt_se);
124 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
126 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
129 static int rt_se_boosted(struct sched_rt_entity *rt_se)
131 struct rt_rq *rt_rq = group_rt_rq(rt_se);
132 struct task_struct *p;
135 return !!rt_rq->rt_nr_boosted;
137 p = rt_task_of(rt_se);
138 return p->prio != p->normal_prio;
142 static inline cpumask_t sched_rt_period_mask(void)
144 return cpu_rq(smp_processor_id())->rd->span;
147 static inline cpumask_t sched_rt_period_mask(void)
149 return cpu_online_map;
154 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
156 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
159 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
161 return &rt_rq->tg->rt_bandwidth;
166 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
168 return rt_rq->rt_runtime;
171 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
173 return ktime_to_ns(def_rt_bandwidth.rt_period);
176 #define for_each_leaf_rt_rq(rt_rq, rq) \
177 for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
179 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
181 return container_of(rt_rq, struct rq, rt);
184 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
186 struct task_struct *p = rt_task_of(rt_se);
187 struct rq *rq = task_rq(p);
192 #define for_each_sched_rt_entity(rt_se) \
193 for (; rt_se; rt_se = NULL)
195 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
200 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
204 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
208 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
210 return rt_rq->rt_throttled;
213 static inline cpumask_t sched_rt_period_mask(void)
215 return cpu_online_map;
219 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
221 return &cpu_rq(cpu)->rt;
224 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
226 return &def_rt_bandwidth;
231 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
236 if (rt_b->rt_runtime == RUNTIME_INF)
239 span = sched_rt_period_mask();
240 for_each_cpu_mask(i, span) {
242 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
243 struct rq *rq = rq_of_rt_rq(rt_rq);
245 spin_lock(&rq->lock);
246 if (rt_rq->rt_time) {
249 spin_lock(&rt_rq->rt_runtime_lock);
250 runtime = rt_rq->rt_runtime;
251 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
252 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
253 rt_rq->rt_throttled = 0;
256 if (rt_rq->rt_time || rt_rq->rt_nr_running)
258 spin_unlock(&rt_rq->rt_runtime_lock);
262 sched_rt_rq_enqueue(rt_rq);
263 spin_unlock(&rq->lock);
270 static int balance_runtime(struct rt_rq *rt_rq)
272 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
273 struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
274 int i, weight, more = 0;
277 weight = cpus_weight(rd->span);
279 spin_lock(&rt_b->rt_runtime_lock);
280 rt_period = ktime_to_ns(rt_b->rt_period);
281 for_each_cpu_mask(i, rd->span) {
282 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
288 spin_lock(&iter->rt_runtime_lock);
289 if (iter->rt_runtime == RUNTIME_INF)
292 diff = iter->rt_runtime - iter->rt_time;
294 do_div(diff, weight);
295 if (rt_rq->rt_runtime + diff > rt_period)
296 diff = rt_period - rt_rq->rt_runtime;
297 iter->rt_runtime -= diff;
298 rt_rq->rt_runtime += diff;
300 if (rt_rq->rt_runtime == rt_period) {
301 spin_unlock(&iter->rt_runtime_lock);
306 spin_unlock(&iter->rt_runtime_lock);
308 spin_unlock(&rt_b->rt_runtime_lock);
313 static void __disable_runtime(struct rq *rq)
315 struct root_domain *rd = rq->rd;
318 if (unlikely(!scheduler_running))
321 for_each_leaf_rt_rq(rt_rq, rq) {
322 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
326 spin_lock(&rt_b->rt_runtime_lock);
327 spin_lock(&rt_rq->rt_runtime_lock);
328 if (rt_rq->rt_runtime == RUNTIME_INF ||
329 rt_rq->rt_runtime == rt_b->rt_runtime)
331 spin_unlock(&rt_rq->rt_runtime_lock);
333 want = rt_b->rt_runtime - rt_rq->rt_runtime;
335 for_each_cpu_mask(i, rd->span) {
336 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
342 spin_lock(&iter->rt_runtime_lock);
344 diff = min_t(s64, iter->rt_runtime, want);
345 iter->rt_runtime -= diff;
348 iter->rt_runtime -= want;
351 spin_unlock(&iter->rt_runtime_lock);
357 spin_lock(&rt_rq->rt_runtime_lock);
360 rt_rq->rt_runtime = RUNTIME_INF;
361 spin_unlock(&rt_rq->rt_runtime_lock);
362 spin_unlock(&rt_b->rt_runtime_lock);
366 static void disable_runtime(struct rq *rq)
370 spin_lock_irqsave(&rq->lock, flags);
371 __disable_runtime(rq);
372 spin_unlock_irqrestore(&rq->lock, flags);
375 static void __enable_runtime(struct rq *rq)
377 struct root_domain *rd = rq->rd;
380 if (unlikely(!scheduler_running))
383 for_each_leaf_rt_rq(rt_rq, rq) {
384 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
386 spin_lock(&rt_b->rt_runtime_lock);
387 spin_lock(&rt_rq->rt_runtime_lock);
388 rt_rq->rt_runtime = rt_b->rt_runtime;
390 spin_unlock(&rt_rq->rt_runtime_lock);
391 spin_unlock(&rt_b->rt_runtime_lock);
395 static void enable_runtime(struct rq *rq)
399 spin_lock_irqsave(&rq->lock, flags);
400 __enable_runtime(rq);
401 spin_unlock_irqrestore(&rq->lock, flags);
406 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
408 #ifdef CONFIG_RT_GROUP_SCHED
409 struct rt_rq *rt_rq = group_rt_rq(rt_se);
412 return rt_rq->highest_prio;
415 return rt_task_of(rt_se)->prio;
418 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
420 u64 runtime = sched_rt_runtime(rt_rq);
422 if (runtime == RUNTIME_INF)
425 if (rt_rq->rt_throttled)
426 return rt_rq_throttled(rt_rq);
428 if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
432 if (rt_rq->rt_time > runtime) {
433 spin_unlock(&rt_rq->rt_runtime_lock);
434 balance_runtime(rt_rq);
435 spin_lock(&rt_rq->rt_runtime_lock);
437 runtime = sched_rt_runtime(rt_rq);
438 if (runtime == RUNTIME_INF)
443 if (rt_rq->rt_time > runtime) {
444 rt_rq->rt_throttled = 1;
445 if (rt_rq_throttled(rt_rq)) {
446 sched_rt_rq_dequeue(rt_rq);
455 * Update the current task's runtime statistics. Skip current tasks that
456 * are not in our scheduling class.
458 static void update_curr_rt(struct rq *rq)
460 struct task_struct *curr = rq->curr;
461 struct sched_rt_entity *rt_se = &curr->rt;
462 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
465 if (!task_has_rt_policy(curr))
468 delta_exec = rq->clock - curr->se.exec_start;
469 if (unlikely((s64)delta_exec < 0))
472 schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec));
474 curr->se.sum_exec_runtime += delta_exec;
475 curr->se.exec_start = rq->clock;
476 cpuacct_charge(curr, delta_exec);
478 for_each_sched_rt_entity(rt_se) {
479 rt_rq = rt_rq_of_se(rt_se);
481 spin_lock(&rt_rq->rt_runtime_lock);
482 rt_rq->rt_time += delta_exec;
483 if (sched_rt_runtime_exceeded(rt_rq))
485 spin_unlock(&rt_rq->rt_runtime_lock);
490 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
492 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
493 rt_rq->rt_nr_running++;
494 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
495 if (rt_se_prio(rt_se) < rt_rq->highest_prio) {
496 struct rq *rq = rq_of_rt_rq(rt_rq);
498 rt_rq->highest_prio = rt_se_prio(rt_se);
501 cpupri_set(&rq->rd->cpupri, rq->cpu,
507 if (rt_se->nr_cpus_allowed > 1) {
508 struct rq *rq = rq_of_rt_rq(rt_rq);
510 rq->rt.rt_nr_migratory++;
513 update_rt_migration(rq_of_rt_rq(rt_rq));
515 #ifdef CONFIG_RT_GROUP_SCHED
516 if (rt_se_boosted(rt_se))
517 rt_rq->rt_nr_boosted++;
520 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
522 start_rt_bandwidth(&def_rt_bandwidth);
527 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
530 int highest_prio = rt_rq->highest_prio;
533 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
534 WARN_ON(!rt_rq->rt_nr_running);
535 rt_rq->rt_nr_running--;
536 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
537 if (rt_rq->rt_nr_running) {
538 struct rt_prio_array *array;
540 WARN_ON(rt_se_prio(rt_se) < rt_rq->highest_prio);
541 if (rt_se_prio(rt_se) == rt_rq->highest_prio) {
543 array = &rt_rq->active;
544 rt_rq->highest_prio =
545 sched_find_first_bit(array->bitmap);
546 } /* otherwise leave rq->highest prio alone */
548 rt_rq->highest_prio = MAX_RT_PRIO;
551 if (rt_se->nr_cpus_allowed > 1) {
552 struct rq *rq = rq_of_rt_rq(rt_rq);
553 rq->rt.rt_nr_migratory--;
556 if (rt_rq->highest_prio != highest_prio) {
557 struct rq *rq = rq_of_rt_rq(rt_rq);
560 cpupri_set(&rq->rd->cpupri, rq->cpu,
561 rt_rq->highest_prio);
564 update_rt_migration(rq_of_rt_rq(rt_rq));
565 #endif /* CONFIG_SMP */
566 #ifdef CONFIG_RT_GROUP_SCHED
567 if (rt_se_boosted(rt_se))
568 rt_rq->rt_nr_boosted--;
570 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
574 static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
576 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
577 struct rt_prio_array *array = &rt_rq->active;
578 struct rt_rq *group_rq = group_rt_rq(rt_se);
579 struct list_head *queue = array->queue + rt_se_prio(rt_se);
581 if (group_rq && rt_rq_throttled(group_rq))
584 if (rt_se->nr_cpus_allowed == 1)
585 list_add(&rt_se->run_list, queue);
587 list_add_tail(&rt_se->run_list, queue);
589 __set_bit(rt_se_prio(rt_se), array->bitmap);
591 inc_rt_tasks(rt_se, rt_rq);
594 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
596 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
597 struct rt_prio_array *array = &rt_rq->active;
599 list_del_init(&rt_se->run_list);
600 if (list_empty(array->queue + rt_se_prio(rt_se)))
601 __clear_bit(rt_se_prio(rt_se), array->bitmap);
603 dec_rt_tasks(rt_se, rt_rq);
607 * Because the prio of an upper entry depends on the lower
608 * entries, we must remove entries top - down.
610 static void dequeue_rt_stack(struct task_struct *p)
612 struct sched_rt_entity *rt_se, *back = NULL;
615 for_each_sched_rt_entity(rt_se) {
620 for (rt_se = back; rt_se; rt_se = rt_se->back) {
622 dequeue_rt_entity(rt_se);
627 * Adding/removing a task to/from a priority array:
629 static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
631 struct sched_rt_entity *rt_se = &p->rt;
639 * enqueue everybody, bottom - up.
641 for_each_sched_rt_entity(rt_se)
642 enqueue_rt_entity(rt_se);
645 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
647 struct sched_rt_entity *rt_se = &p->rt;
655 * re-enqueue all non-empty rt_rq entities.
657 for_each_sched_rt_entity(rt_se) {
658 rt_rq = group_rt_rq(rt_se);
659 if (rt_rq && rt_rq->rt_nr_running)
660 enqueue_rt_entity(rt_se);
665 * Put task to the end of the run list without the overhead of dequeue
666 * followed by enqueue.
669 void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
671 struct rt_prio_array *array = &rt_rq->active;
673 list_del_init(&rt_se->run_list);
674 list_add_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
677 static void requeue_task_rt(struct rq *rq, struct task_struct *p)
679 struct sched_rt_entity *rt_se = &p->rt;
682 for_each_sched_rt_entity(rt_se) {
683 rt_rq = rt_rq_of_se(rt_se);
684 requeue_rt_entity(rt_rq, rt_se);
688 static void yield_task_rt(struct rq *rq)
690 requeue_task_rt(rq, rq->curr);
694 static int find_lowest_rq(struct task_struct *task);
696 static int select_task_rq_rt(struct task_struct *p, int sync)
698 struct rq *rq = task_rq(p);
701 * If the current task is an RT task, then
702 * try to see if we can wake this RT task up on another
703 * runqueue. Otherwise simply start this RT task
704 * on its current runqueue.
706 * We want to avoid overloading runqueues. Even if
707 * the RT task is of higher priority than the current RT task.
708 * RT tasks behave differently than other tasks. If
709 * one gets preempted, we try to push it off to another queue.
710 * So trying to keep a preempting RT task on the same
711 * cache hot CPU will force the running RT task to
712 * a cold CPU. So we waste all the cache for the lower
713 * RT task in hopes of saving some of a RT task
714 * that is just being woken and probably will have
717 if (unlikely(rt_task(rq->curr)) &&
718 (p->rt.nr_cpus_allowed > 1)) {
719 int cpu = find_lowest_rq(p);
721 return (cpu == -1) ? task_cpu(p) : cpu;
725 * Otherwise, just let it ride on the affined RQ and the
726 * post-schedule router will push the preempted task away
730 #endif /* CONFIG_SMP */
733 * Preempt the current task with a newly woken task if needed:
735 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
737 if (p->prio < rq->curr->prio) {
738 resched_task(rq->curr);
746 * - the newly woken task is of equal priority to the current task
747 * - the newly woken task is non-migratable while current is migratable
748 * - current will be preempted on the next reschedule
750 * we should check to see if current can readily move to a different
751 * cpu. If so, we will reschedule to allow the push logic to try
752 * to move current somewhere else, making room for our non-migratable
755 if((p->prio == rq->curr->prio)
756 && p->rt.nr_cpus_allowed == 1
757 && rq->curr->rt.nr_cpus_allowed != 1) {
760 if (cpupri_find(&rq->rd->cpupri, rq->curr, &mask))
762 * There appears to be other cpus that can accept
763 * current, so lets reschedule to try and push it away
765 resched_task(rq->curr);
770 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
773 struct rt_prio_array *array = &rt_rq->active;
774 struct sched_rt_entity *next = NULL;
775 struct list_head *queue;
778 idx = sched_find_first_bit(array->bitmap);
779 BUG_ON(idx >= MAX_RT_PRIO);
781 queue = array->queue + idx;
782 next = list_entry(queue->next, struct sched_rt_entity, run_list);
787 static struct task_struct *pick_next_task_rt(struct rq *rq)
789 struct sched_rt_entity *rt_se;
790 struct task_struct *p;
795 if (unlikely(!rt_rq->rt_nr_running))
798 if (rt_rq_throttled(rt_rq))
802 rt_se = pick_next_rt_entity(rq, rt_rq);
804 rt_rq = group_rt_rq(rt_se);
807 p = rt_task_of(rt_se);
808 p->se.exec_start = rq->clock;
812 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
815 p->se.exec_start = 0;
820 /* Only try algorithms three times */
821 #define RT_MAX_TRIES 3
823 static int double_lock_balance(struct rq *this_rq, struct rq *busiest);
824 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
826 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
828 if (!task_running(rq, p) &&
829 (cpu < 0 || cpu_isset(cpu, p->cpus_allowed)) &&
830 (p->rt.nr_cpus_allowed > 1))
835 /* Return the second highest RT task, NULL otherwise */
836 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
838 struct task_struct *next = NULL;
839 struct sched_rt_entity *rt_se;
840 struct rt_prio_array *array;
844 for_each_leaf_rt_rq(rt_rq, rq) {
845 array = &rt_rq->active;
846 idx = sched_find_first_bit(array->bitmap);
848 if (idx >= MAX_RT_PRIO)
850 if (next && next->prio < idx)
852 list_for_each_entry(rt_se, array->queue + idx, run_list) {
853 struct task_struct *p = rt_task_of(rt_se);
854 if (pick_rt_task(rq, p, cpu)) {
860 idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
868 static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);
870 static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask)
874 /* "this_cpu" is cheaper to preempt than a remote processor */
875 if ((this_cpu != -1) && cpu_isset(this_cpu, *mask))
878 first = first_cpu(*mask);
879 if (first != NR_CPUS)
885 static int find_lowest_rq(struct task_struct *task)
887 struct sched_domain *sd;
888 cpumask_t *lowest_mask = &__get_cpu_var(local_cpu_mask);
889 int this_cpu = smp_processor_id();
890 int cpu = task_cpu(task);
892 if (task->rt.nr_cpus_allowed == 1)
893 return -1; /* No other targets possible */
895 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
896 return -1; /* No targets found */
899 * At this point we have built a mask of cpus representing the
900 * lowest priority tasks in the system. Now we want to elect
901 * the best one based on our affinity and topology.
903 * We prioritize the last cpu that the task executed on since
904 * it is most likely cache-hot in that location.
906 if (cpu_isset(cpu, *lowest_mask))
910 * Otherwise, we consult the sched_domains span maps to figure
911 * out which cpu is logically closest to our hot cache data.
914 this_cpu = -1; /* Skip this_cpu opt if the same */
916 for_each_domain(cpu, sd) {
917 if (sd->flags & SD_WAKE_AFFINE) {
918 cpumask_t domain_mask;
921 cpus_and(domain_mask, sd->span, *lowest_mask);
923 best_cpu = pick_optimal_cpu(this_cpu,
931 * And finally, if there were no matches within the domains
932 * just give the caller *something* to work with from the compatible
935 return pick_optimal_cpu(this_cpu, lowest_mask);
938 /* Will lock the rq it finds */
939 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
941 struct rq *lowest_rq = NULL;
945 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
946 cpu = find_lowest_rq(task);
948 if ((cpu == -1) || (cpu == rq->cpu))
951 lowest_rq = cpu_rq(cpu);
953 /* if the prio of this runqueue changed, try again */
954 if (double_lock_balance(rq, lowest_rq)) {
956 * We had to unlock the run queue. In
957 * the mean time, task could have
958 * migrated already or had its affinity changed.
959 * Also make sure that it wasn't scheduled on its rq.
961 if (unlikely(task_rq(task) != rq ||
962 !cpu_isset(lowest_rq->cpu,
963 task->cpus_allowed) ||
964 task_running(rq, task) ||
967 spin_unlock(&lowest_rq->lock);
973 /* If this rq is still suitable use it. */
974 if (lowest_rq->rt.highest_prio > task->prio)
978 spin_unlock(&lowest_rq->lock);
986 * If the current CPU has more than one RT task, see if the non
987 * running task can migrate over to a CPU that is running a task
988 * of lesser priority.
990 static int push_rt_task(struct rq *rq)
992 struct task_struct *next_task;
993 struct rq *lowest_rq;
995 int paranoid = RT_MAX_TRIES;
997 if (!rq->rt.overloaded)
1000 next_task = pick_next_highest_task_rt(rq, -1);
1005 if (unlikely(next_task == rq->curr)) {
1011 * It's possible that the next_task slipped in of
1012 * higher priority than current. If that's the case
1013 * just reschedule current.
1015 if (unlikely(next_task->prio < rq->curr->prio)) {
1016 resched_task(rq->curr);
1020 /* We might release rq lock */
1021 get_task_struct(next_task);
1023 /* find_lock_lowest_rq locks the rq if found */
1024 lowest_rq = find_lock_lowest_rq(next_task, rq);
1026 struct task_struct *task;
1028 * find lock_lowest_rq releases rq->lock
1029 * so it is possible that next_task has changed.
1030 * If it has, then try again.
1032 task = pick_next_highest_task_rt(rq, -1);
1033 if (unlikely(task != next_task) && task && paranoid--) {
1034 put_task_struct(next_task);
1041 deactivate_task(rq, next_task, 0);
1042 set_task_cpu(next_task, lowest_rq->cpu);
1043 activate_task(lowest_rq, next_task, 0);
1045 resched_task(lowest_rq->curr);
1047 spin_unlock(&lowest_rq->lock);
1051 put_task_struct(next_task);
1057 * TODO: Currently we just use the second highest prio task on
1058 * the queue, and stop when it can't migrate (or there's
1059 * no more RT tasks). There may be a case where a lower
1060 * priority RT task has a different affinity than the
1061 * higher RT task. In this case the lower RT task could
1062 * possibly be able to migrate where as the higher priority
1063 * RT task could not. We currently ignore this issue.
1064 * Enhancements are welcome!
1066 static void push_rt_tasks(struct rq *rq)
1068 /* push_rt_task will return true if it moved an RT */
1069 while (push_rt_task(rq))
1073 static int pull_rt_task(struct rq *this_rq)
1075 int this_cpu = this_rq->cpu, ret = 0, cpu;
1076 struct task_struct *p, *next;
1079 if (likely(!rt_overloaded(this_rq)))
1082 next = pick_next_task_rt(this_rq);
1084 for_each_cpu_mask(cpu, this_rq->rd->rto_mask) {
1085 if (this_cpu == cpu)
1088 src_rq = cpu_rq(cpu);
1090 * We can potentially drop this_rq's lock in
1091 * double_lock_balance, and another CPU could
1092 * steal our next task - hence we must cause
1093 * the caller to recalculate the next task
1096 if (double_lock_balance(this_rq, src_rq)) {
1097 struct task_struct *old_next = next;
1099 next = pick_next_task_rt(this_rq);
1100 if (next != old_next)
1105 * Are there still pullable RT tasks?
1107 if (src_rq->rt.rt_nr_running <= 1)
1110 p = pick_next_highest_task_rt(src_rq, this_cpu);
1113 * Do we have an RT task that preempts
1114 * the to-be-scheduled task?
1116 if (p && (!next || (p->prio < next->prio))) {
1117 WARN_ON(p == src_rq->curr);
1118 WARN_ON(!p->se.on_rq);
1121 * There's a chance that p is higher in priority
1122 * than what's currently running on its cpu.
1123 * This is just that p is wakeing up and hasn't
1124 * had a chance to schedule. We only pull
1125 * p if it is lower in priority than the
1126 * current task on the run queue or
1127 * this_rq next task is lower in prio than
1128 * the current task on that rq.
1130 if (p->prio < src_rq->curr->prio ||
1131 (next && next->prio < src_rq->curr->prio))
1136 deactivate_task(src_rq, p, 0);
1137 set_task_cpu(p, this_cpu);
1138 activate_task(this_rq, p, 0);
1140 * We continue with the search, just in
1141 * case there's an even higher prio task
1142 * in another runqueue. (low likelyhood
1145 * Update next so that we won't pick a task
1146 * on another cpu with a priority lower (or equal)
1147 * than the one we just picked.
1153 spin_unlock(&src_rq->lock);
1159 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1161 /* Try to pull RT tasks here if we lower this rq's prio */
1162 if (unlikely(rt_task(prev)) && rq->rt.highest_prio > prev->prio)
1166 static void post_schedule_rt(struct rq *rq)
1169 * If we have more than one rt_task queued, then
1170 * see if we can push the other rt_tasks off to other CPUS.
1171 * Note we may release the rq lock, and since
1172 * the lock was owned by prev, we need to release it
1173 * first via finish_lock_switch and then reaquire it here.
1175 if (unlikely(rq->rt.overloaded)) {
1176 spin_lock_irq(&rq->lock);
1178 spin_unlock_irq(&rq->lock);
1183 * If we are not running and we are not going to reschedule soon, we should
1184 * try to push tasks away now
1186 static void task_wake_up_rt(struct rq *rq, struct task_struct *p)
1188 if (!task_running(rq, p) &&
1189 !test_tsk_need_resched(rq->curr) &&
1194 static unsigned long
1195 load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
1196 unsigned long max_load_move,
1197 struct sched_domain *sd, enum cpu_idle_type idle,
1198 int *all_pinned, int *this_best_prio)
1200 /* don't touch RT tasks */
1205 move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
1206 struct sched_domain *sd, enum cpu_idle_type idle)
1208 /* don't touch RT tasks */
1212 static void set_cpus_allowed_rt(struct task_struct *p,
1213 const cpumask_t *new_mask)
1215 int weight = cpus_weight(*new_mask);
1217 BUG_ON(!rt_task(p));
1220 * Update the migration status of the RQ if we have an RT task
1221 * which is running AND changing its weight value.
1223 if (p->se.on_rq && (weight != p->rt.nr_cpus_allowed)) {
1224 struct rq *rq = task_rq(p);
1226 if ((p->rt.nr_cpus_allowed <= 1) && (weight > 1)) {
1227 rq->rt.rt_nr_migratory++;
1228 } else if ((p->rt.nr_cpus_allowed > 1) && (weight <= 1)) {
1229 BUG_ON(!rq->rt.rt_nr_migratory);
1230 rq->rt.rt_nr_migratory--;
1233 update_rt_migration(rq);
1236 p->cpus_allowed = *new_mask;
1237 p->rt.nr_cpus_allowed = weight;
1240 /* Assumes rq->lock is held */
1241 static void rq_online_rt(struct rq *rq)
1243 if (rq->rt.overloaded)
1244 rt_set_overload(rq);
1246 __enable_runtime(rq);
1248 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio);
1251 /* Assumes rq->lock is held */
1252 static void rq_offline_rt(struct rq *rq)
1254 if (rq->rt.overloaded)
1255 rt_clear_overload(rq);
1257 __disable_runtime(rq);
1259 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1263 * When switch from the rt queue, we bring ourselves to a position
1264 * that we might want to pull RT tasks from other runqueues.
1266 static void switched_from_rt(struct rq *rq, struct task_struct *p,
1270 * If there are other RT tasks then we will reschedule
1271 * and the scheduling of the other RT tasks will handle
1272 * the balancing. But if we are the last RT task
1273 * we may need to handle the pulling of RT tasks
1276 if (!rq->rt.rt_nr_running)
1279 #endif /* CONFIG_SMP */
1282 * When switching a task to RT, we may overload the runqueue
1283 * with RT tasks. In this case we try to push them off to
1286 static void switched_to_rt(struct rq *rq, struct task_struct *p,
1289 int check_resched = 1;
1292 * If we are already running, then there's nothing
1293 * that needs to be done. But if we are not running
1294 * we may need to preempt the current running task.
1295 * If that current running task is also an RT task
1296 * then see if we can move to another run queue.
1300 if (rq->rt.overloaded && push_rt_task(rq) &&
1301 /* Don't resched if we changed runqueues */
1304 #endif /* CONFIG_SMP */
1305 if (check_resched && p->prio < rq->curr->prio)
1306 resched_task(rq->curr);
1311 * Priority of the task has changed. This may cause
1312 * us to initiate a push or pull.
1314 static void prio_changed_rt(struct rq *rq, struct task_struct *p,
1315 int oldprio, int running)
1320 * If our priority decreases while running, we
1321 * may need to pull tasks to this runqueue.
1323 if (oldprio < p->prio)
1326 * If there's a higher priority task waiting to run
1327 * then reschedule. Note, the above pull_rt_task
1328 * can release the rq lock and p could migrate.
1329 * Only reschedule if p is still on the same runqueue.
1331 if (p->prio > rq->rt.highest_prio && rq->curr == p)
1334 /* For UP simply resched on drop of prio */
1335 if (oldprio < p->prio)
1337 #endif /* CONFIG_SMP */
1340 * This task is not running, but if it is
1341 * greater than the current running task
1344 if (p->prio < rq->curr->prio)
1345 resched_task(rq->curr);
1349 static void watchdog(struct rq *rq, struct task_struct *p)
1351 unsigned long soft, hard;
1356 soft = p->signal->rlim[RLIMIT_RTTIME].rlim_cur;
1357 hard = p->signal->rlim[RLIMIT_RTTIME].rlim_max;
1359 if (soft != RLIM_INFINITY) {
1363 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1364 if (p->rt.timeout > next)
1365 p->it_sched_expires = p->se.sum_exec_runtime;
1369 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1376 * RR tasks need a special form of timeslice management.
1377 * FIFO tasks have no timeslices.
1379 if (p->policy != SCHED_RR)
1382 if (--p->rt.time_slice)
1385 p->rt.time_slice = DEF_TIMESLICE;
1388 * Requeue to the end of queue if we are not the only element
1391 if (p->rt.run_list.prev != p->rt.run_list.next) {
1392 requeue_task_rt(rq, p);
1393 set_tsk_need_resched(p);
1397 static void set_curr_task_rt(struct rq *rq)
1399 struct task_struct *p = rq->curr;
1401 p->se.exec_start = rq->clock;
1404 static const struct sched_class rt_sched_class = {
1405 .next = &fair_sched_class,
1406 .enqueue_task = enqueue_task_rt,
1407 .dequeue_task = dequeue_task_rt,
1408 .yield_task = yield_task_rt,
1410 .select_task_rq = select_task_rq_rt,
1411 #endif /* CONFIG_SMP */
1413 .check_preempt_curr = check_preempt_curr_rt,
1415 .pick_next_task = pick_next_task_rt,
1416 .put_prev_task = put_prev_task_rt,
1419 .load_balance = load_balance_rt,
1420 .move_one_task = move_one_task_rt,
1421 .set_cpus_allowed = set_cpus_allowed_rt,
1422 .rq_online = rq_online_rt,
1423 .rq_offline = rq_offline_rt,
1424 .pre_schedule = pre_schedule_rt,
1425 .post_schedule = post_schedule_rt,
1426 .task_wake_up = task_wake_up_rt,
1427 .switched_from = switched_from_rt,
1430 .set_curr_task = set_curr_task_rt,
1431 .task_tick = task_tick_rt,
1433 .prio_changed = prio_changed_rt,
1434 .switched_to = switched_to_rt,