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 int pull_rt_task(struct rq
*this_rq
);
234 static inline bool need_pull_rt_task(struct rq
*rq
, struct task_struct
*prev
)
236 /* Try to pull RT tasks here if we lower this rq's prio */
237 return rq
->rt
.highest_prio
.curr
> prev
->prio
;
240 static inline int rt_overloaded(struct rq
*rq
)
242 return atomic_read(&rq
->rd
->rto_count
);
245 static inline void rt_set_overload(struct rq
*rq
)
250 cpumask_set_cpu(rq
->cpu
, rq
->rd
->rto_mask
);
252 * Make sure the mask is visible before we set
253 * the overload count. That is checked to determine
254 * if we should look at the mask. It would be a shame
255 * if we looked at the mask, but the mask was not
258 * Matched by the barrier in pull_rt_task().
261 atomic_inc(&rq
->rd
->rto_count
);
264 static inline void rt_clear_overload(struct rq
*rq
)
269 /* the order here really doesn't matter */
270 atomic_dec(&rq
->rd
->rto_count
);
271 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->rto_mask
);
274 static void update_rt_migration(struct rt_rq
*rt_rq
)
276 if (rt_rq
->rt_nr_migratory
&& rt_rq
->rt_nr_total
> 1) {
277 if (!rt_rq
->overloaded
) {
278 rt_set_overload(rq_of_rt_rq(rt_rq
));
279 rt_rq
->overloaded
= 1;
281 } else if (rt_rq
->overloaded
) {
282 rt_clear_overload(rq_of_rt_rq(rt_rq
));
283 rt_rq
->overloaded
= 0;
287 static void inc_rt_migration(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
)
289 struct task_struct
*p
;
291 if (!rt_entity_is_task(rt_se
))
294 p
= rt_task_of(rt_se
);
295 rt_rq
= &rq_of_rt_rq(rt_rq
)->rt
;
297 rt_rq
->rt_nr_total
++;
298 if (p
->nr_cpus_allowed
> 1)
299 rt_rq
->rt_nr_migratory
++;
301 update_rt_migration(rt_rq
);
304 static void dec_rt_migration(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
)
306 struct task_struct
*p
;
308 if (!rt_entity_is_task(rt_se
))
311 p
= rt_task_of(rt_se
);
312 rt_rq
= &rq_of_rt_rq(rt_rq
)->rt
;
314 rt_rq
->rt_nr_total
--;
315 if (p
->nr_cpus_allowed
> 1)
316 rt_rq
->rt_nr_migratory
--;
318 update_rt_migration(rt_rq
);
321 static inline int has_pushable_tasks(struct rq
*rq
)
323 return !plist_head_empty(&rq
->rt
.pushable_tasks
);
326 static inline void set_post_schedule(struct rq
*rq
)
329 * We detect this state here so that we can avoid taking the RQ
330 * lock again later if there is no need to push
332 rq
->post_schedule
= has_pushable_tasks(rq
);
335 static void enqueue_pushable_task(struct rq
*rq
, struct task_struct
*p
)
337 plist_del(&p
->pushable_tasks
, &rq
->rt
.pushable_tasks
);
338 plist_node_init(&p
->pushable_tasks
, p
->prio
);
339 plist_add(&p
->pushable_tasks
, &rq
->rt
.pushable_tasks
);
341 /* Update the highest prio pushable task */
342 if (p
->prio
< rq
->rt
.highest_prio
.next
)
343 rq
->rt
.highest_prio
.next
= p
->prio
;
346 static void dequeue_pushable_task(struct rq
*rq
, struct task_struct
*p
)
348 plist_del(&p
->pushable_tasks
, &rq
->rt
.pushable_tasks
);
350 /* Update the new highest prio pushable task */
351 if (has_pushable_tasks(rq
)) {
352 p
= plist_first_entry(&rq
->rt
.pushable_tasks
,
353 struct task_struct
, pushable_tasks
);
354 rq
->rt
.highest_prio
.next
= p
->prio
;
356 rq
->rt
.highest_prio
.next
= MAX_RT_PRIO
;
361 static inline void enqueue_pushable_task(struct rq
*rq
, struct task_struct
*p
)
365 static inline void dequeue_pushable_task(struct rq
*rq
, struct task_struct
*p
)
370 void inc_rt_migration(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
)
375 void dec_rt_migration(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
)
379 static inline bool need_pull_rt_task(struct rq
*rq
, struct task_struct
*prev
)
384 static inline int pull_rt_task(struct rq
*this_rq
)
389 static inline void set_post_schedule(struct rq
*rq
)
392 #endif /* CONFIG_SMP */
394 static inline int on_rt_rq(struct sched_rt_entity
*rt_se
)
396 return !list_empty(&rt_se
->run_list
);
399 #ifdef CONFIG_RT_GROUP_SCHED
401 static inline u64
sched_rt_runtime(struct rt_rq
*rt_rq
)
406 return rt_rq
->rt_runtime
;
409 static inline u64
sched_rt_period(struct rt_rq
*rt_rq
)
411 return ktime_to_ns(rt_rq
->tg
->rt_bandwidth
.rt_period
);
414 typedef struct task_group
*rt_rq_iter_t
;
416 static inline struct task_group
*next_task_group(struct task_group
*tg
)
419 tg
= list_entry_rcu(tg
->list
.next
,
420 typeof(struct task_group
), list
);
421 } while (&tg
->list
!= &task_groups
&& task_group_is_autogroup(tg
));
423 if (&tg
->list
== &task_groups
)
429 #define for_each_rt_rq(rt_rq, iter, rq) \
430 for (iter = container_of(&task_groups, typeof(*iter), list); \
431 (iter = next_task_group(iter)) && \
432 (rt_rq = iter->rt_rq[cpu_of(rq)]);)
434 #define for_each_sched_rt_entity(rt_se) \
435 for (; rt_se; rt_se = rt_se->parent)
437 static inline struct rt_rq
*group_rt_rq(struct sched_rt_entity
*rt_se
)
442 static void enqueue_rt_entity(struct sched_rt_entity
*rt_se
, bool head
);
443 static void dequeue_rt_entity(struct sched_rt_entity
*rt_se
);
445 static void sched_rt_rq_enqueue(struct rt_rq
*rt_rq
)
447 struct task_struct
*curr
= rq_of_rt_rq(rt_rq
)->curr
;
448 struct sched_rt_entity
*rt_se
;
450 int cpu
= cpu_of(rq_of_rt_rq(rt_rq
));
452 rt_se
= rt_rq
->tg
->rt_se
[cpu
];
454 if (rt_rq
->rt_nr_running
) {
455 if (rt_se
&& !on_rt_rq(rt_se
))
456 enqueue_rt_entity(rt_se
, false);
457 if (rt_rq
->highest_prio
.curr
< curr
->prio
)
462 static void sched_rt_rq_dequeue(struct rt_rq
*rt_rq
)
464 struct sched_rt_entity
*rt_se
;
465 int cpu
= cpu_of(rq_of_rt_rq(rt_rq
));
467 rt_se
= rt_rq
->tg
->rt_se
[cpu
];
469 if (rt_se
&& on_rt_rq(rt_se
))
470 dequeue_rt_entity(rt_se
);
473 static int rt_se_boosted(struct sched_rt_entity
*rt_se
)
475 struct rt_rq
*rt_rq
= group_rt_rq(rt_se
);
476 struct task_struct
*p
;
479 return !!rt_rq
->rt_nr_boosted
;
481 p
= rt_task_of(rt_se
);
482 return p
->prio
!= p
->normal_prio
;
486 static inline const struct cpumask
*sched_rt_period_mask(void)
488 return this_rq()->rd
->span
;
491 static inline const struct cpumask
*sched_rt_period_mask(void)
493 return cpu_online_mask
;
498 struct rt_rq
*sched_rt_period_rt_rq(struct rt_bandwidth
*rt_b
, int cpu
)
500 return container_of(rt_b
, struct task_group
, rt_bandwidth
)->rt_rq
[cpu
];
503 static inline struct rt_bandwidth
*sched_rt_bandwidth(struct rt_rq
*rt_rq
)
505 return &rt_rq
->tg
->rt_bandwidth
;
508 #else /* !CONFIG_RT_GROUP_SCHED */
510 static inline u64
sched_rt_runtime(struct rt_rq
*rt_rq
)
512 return rt_rq
->rt_runtime
;
515 static inline u64
sched_rt_period(struct rt_rq
*rt_rq
)
517 return ktime_to_ns(def_rt_bandwidth
.rt_period
);
520 typedef struct rt_rq
*rt_rq_iter_t
;
522 #define for_each_rt_rq(rt_rq, iter, rq) \
523 for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
525 #define for_each_sched_rt_entity(rt_se) \
526 for (; rt_se; rt_se = NULL)
528 static inline struct rt_rq
*group_rt_rq(struct sched_rt_entity
*rt_se
)
533 static inline void sched_rt_rq_enqueue(struct rt_rq
*rt_rq
)
535 if (rt_rq
->rt_nr_running
)
536 resched_task(rq_of_rt_rq(rt_rq
)->curr
);
539 static inline void sched_rt_rq_dequeue(struct rt_rq
*rt_rq
)
543 static inline const struct cpumask
*sched_rt_period_mask(void)
545 return cpu_online_mask
;
549 struct rt_rq
*sched_rt_period_rt_rq(struct rt_bandwidth
*rt_b
, int cpu
)
551 return &cpu_rq(cpu
)->rt
;
554 static inline struct rt_bandwidth
*sched_rt_bandwidth(struct rt_rq
*rt_rq
)
556 return &def_rt_bandwidth
;
559 #endif /* CONFIG_RT_GROUP_SCHED */
561 bool sched_rt_bandwidth_account(struct rt_rq
*rt_rq
)
563 struct rt_bandwidth
*rt_b
= sched_rt_bandwidth(rt_rq
);
565 return (hrtimer_active(&rt_b
->rt_period_timer
) ||
566 rt_rq
->rt_time
< rt_b
->rt_runtime
);
571 * We ran out of runtime, see if we can borrow some from our neighbours.
573 static int do_balance_runtime(struct rt_rq
*rt_rq
)
575 struct rt_bandwidth
*rt_b
= sched_rt_bandwidth(rt_rq
);
576 struct root_domain
*rd
= rq_of_rt_rq(rt_rq
)->rd
;
577 int i
, weight
, more
= 0;
580 weight
= cpumask_weight(rd
->span
);
582 raw_spin_lock(&rt_b
->rt_runtime_lock
);
583 rt_period
= ktime_to_ns(rt_b
->rt_period
);
584 for_each_cpu(i
, rd
->span
) {
585 struct rt_rq
*iter
= sched_rt_period_rt_rq(rt_b
, i
);
591 raw_spin_lock(&iter
->rt_runtime_lock
);
593 * Either all rqs have inf runtime and there's nothing to steal
594 * or __disable_runtime() below sets a specific rq to inf to
595 * indicate its been disabled and disalow stealing.
597 if (iter
->rt_runtime
== RUNTIME_INF
)
601 * From runqueues with spare time, take 1/n part of their
602 * spare time, but no more than our period.
604 diff
= iter
->rt_runtime
- iter
->rt_time
;
606 diff
= div_u64((u64
)diff
, weight
);
607 if (rt_rq
->rt_runtime
+ diff
> rt_period
)
608 diff
= rt_period
- rt_rq
->rt_runtime
;
609 iter
->rt_runtime
-= diff
;
610 rt_rq
->rt_runtime
+= diff
;
612 if (rt_rq
->rt_runtime
== rt_period
) {
613 raw_spin_unlock(&iter
->rt_runtime_lock
);
618 raw_spin_unlock(&iter
->rt_runtime_lock
);
620 raw_spin_unlock(&rt_b
->rt_runtime_lock
);
626 * Ensure this RQ takes back all the runtime it lend to its neighbours.
628 static void __disable_runtime(struct rq
*rq
)
630 struct root_domain
*rd
= rq
->rd
;
634 if (unlikely(!scheduler_running
))
637 for_each_rt_rq(rt_rq
, iter
, rq
) {
638 struct rt_bandwidth
*rt_b
= sched_rt_bandwidth(rt_rq
);
642 raw_spin_lock(&rt_b
->rt_runtime_lock
);
643 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
645 * Either we're all inf and nobody needs to borrow, or we're
646 * already disabled and thus have nothing to do, or we have
647 * exactly the right amount of runtime to take out.
649 if (rt_rq
->rt_runtime
== RUNTIME_INF
||
650 rt_rq
->rt_runtime
== rt_b
->rt_runtime
)
652 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
655 * Calculate the difference between what we started out with
656 * and what we current have, that's the amount of runtime
657 * we lend and now have to reclaim.
659 want
= rt_b
->rt_runtime
- rt_rq
->rt_runtime
;
662 * Greedy reclaim, take back as much as we can.
664 for_each_cpu(i
, rd
->span
) {
665 struct rt_rq
*iter
= sched_rt_period_rt_rq(rt_b
, i
);
669 * Can't reclaim from ourselves or disabled runqueues.
671 if (iter
== rt_rq
|| iter
->rt_runtime
== RUNTIME_INF
)
674 raw_spin_lock(&iter
->rt_runtime_lock
);
676 diff
= min_t(s64
, iter
->rt_runtime
, want
);
677 iter
->rt_runtime
-= diff
;
680 iter
->rt_runtime
-= want
;
683 raw_spin_unlock(&iter
->rt_runtime_lock
);
689 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
691 * We cannot be left wanting - that would mean some runtime
692 * leaked out of the system.
697 * Disable all the borrow logic by pretending we have inf
698 * runtime - in which case borrowing doesn't make sense.
700 rt_rq
->rt_runtime
= RUNTIME_INF
;
701 rt_rq
->rt_throttled
= 0;
702 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
703 raw_spin_unlock(&rt_b
->rt_runtime_lock
);
707 static void __enable_runtime(struct rq
*rq
)
712 if (unlikely(!scheduler_running
))
716 * Reset each runqueue's bandwidth settings
718 for_each_rt_rq(rt_rq
, iter
, rq
) {
719 struct rt_bandwidth
*rt_b
= sched_rt_bandwidth(rt_rq
);
721 raw_spin_lock(&rt_b
->rt_runtime_lock
);
722 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
723 rt_rq
->rt_runtime
= rt_b
->rt_runtime
;
725 rt_rq
->rt_throttled
= 0;
726 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
727 raw_spin_unlock(&rt_b
->rt_runtime_lock
);
731 static int balance_runtime(struct rt_rq
*rt_rq
)
735 if (!sched_feat(RT_RUNTIME_SHARE
))
738 if (rt_rq
->rt_time
> rt_rq
->rt_runtime
) {
739 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
740 more
= do_balance_runtime(rt_rq
);
741 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
746 #else /* !CONFIG_SMP */
747 static inline int balance_runtime(struct rt_rq
*rt_rq
)
751 #endif /* CONFIG_SMP */
753 static int do_sched_rt_period_timer(struct rt_bandwidth
*rt_b
, int overrun
)
755 int i
, idle
= 1, throttled
= 0;
756 const struct cpumask
*span
;
758 span
= sched_rt_period_mask();
759 #ifdef CONFIG_RT_GROUP_SCHED
761 * FIXME: isolated CPUs should really leave the root task group,
762 * whether they are isolcpus or were isolated via cpusets, lest
763 * the timer run on a CPU which does not service all runqueues,
764 * potentially leaving other CPUs indefinitely throttled. If
765 * isolation is really required, the user will turn the throttle
766 * off to kill the perturbations it causes anyway. Meanwhile,
767 * this maintains functionality for boot and/or troubleshooting.
769 if (rt_b
== &root_task_group
.rt_bandwidth
)
770 span
= cpu_online_mask
;
772 for_each_cpu(i
, span
) {
774 struct rt_rq
*rt_rq
= sched_rt_period_rt_rq(rt_b
, i
);
775 struct rq
*rq
= rq_of_rt_rq(rt_rq
);
777 raw_spin_lock(&rq
->lock
);
778 if (rt_rq
->rt_time
) {
781 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
782 if (rt_rq
->rt_throttled
)
783 balance_runtime(rt_rq
);
784 runtime
= rt_rq
->rt_runtime
;
785 rt_rq
->rt_time
-= min(rt_rq
->rt_time
, overrun
*runtime
);
786 if (rt_rq
->rt_throttled
&& rt_rq
->rt_time
< runtime
) {
787 rt_rq
->rt_throttled
= 0;
791 * Force a clock update if the CPU was idle,
792 * lest wakeup -> unthrottle time accumulate.
794 if (rt_rq
->rt_nr_running
&& rq
->curr
== rq
->idle
)
795 rq
->skip_clock_update
= -1;
797 if (rt_rq
->rt_time
|| rt_rq
->rt_nr_running
)
799 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
800 } else if (rt_rq
->rt_nr_running
) {
802 if (!rt_rq_throttled(rt_rq
))
805 if (rt_rq
->rt_throttled
)
809 sched_rt_rq_enqueue(rt_rq
);
810 raw_spin_unlock(&rq
->lock
);
813 if (!throttled
&& (!rt_bandwidth_enabled() || rt_b
->rt_runtime
== RUNTIME_INF
))
819 static inline int rt_se_prio(struct sched_rt_entity
*rt_se
)
821 #ifdef CONFIG_RT_GROUP_SCHED
822 struct rt_rq
*rt_rq
= group_rt_rq(rt_se
);
825 return rt_rq
->highest_prio
.curr
;
828 return rt_task_of(rt_se
)->prio
;
831 static int sched_rt_runtime_exceeded(struct rt_rq
*rt_rq
)
833 u64 runtime
= sched_rt_runtime(rt_rq
);
835 if (rt_rq
->rt_throttled
)
836 return rt_rq_throttled(rt_rq
);
838 if (runtime
>= sched_rt_period(rt_rq
))
841 balance_runtime(rt_rq
);
842 runtime
= sched_rt_runtime(rt_rq
);
843 if (runtime
== RUNTIME_INF
)
846 if (rt_rq
->rt_time
> runtime
) {
847 struct rt_bandwidth
*rt_b
= sched_rt_bandwidth(rt_rq
);
850 * Don't actually throttle groups that have no runtime assigned
851 * but accrue some time due to boosting.
853 if (likely(rt_b
->rt_runtime
)) {
854 static bool once
= false;
856 rt_rq
->rt_throttled
= 1;
860 printk_sched("sched: RT throttling activated\n");
864 * In case we did anyway, make it go away,
865 * replenishment is a joke, since it will replenish us
871 if (rt_rq_throttled(rt_rq
)) {
872 sched_rt_rq_dequeue(rt_rq
);
881 * Update the current task's runtime statistics. Skip current tasks that
882 * are not in our scheduling class.
884 static void update_curr_rt(struct rq
*rq
)
886 struct task_struct
*curr
= rq
->curr
;
887 struct sched_rt_entity
*rt_se
= &curr
->rt
;
888 struct rt_rq
*rt_rq
= rt_rq_of_se(rt_se
);
891 if (curr
->sched_class
!= &rt_sched_class
)
894 delta_exec
= rq_clock_task(rq
) - curr
->se
.exec_start
;
895 if (unlikely((s64
)delta_exec
<= 0))
898 schedstat_set(curr
->se
.statistics
.exec_max
,
899 max(curr
->se
.statistics
.exec_max
, delta_exec
));
901 curr
->se
.sum_exec_runtime
+= delta_exec
;
902 account_group_exec_runtime(curr
, delta_exec
);
904 curr
->se
.exec_start
= rq_clock_task(rq
);
905 cpuacct_charge(curr
, delta_exec
);
907 sched_rt_avg_update(rq
, delta_exec
);
909 if (!rt_bandwidth_enabled())
912 for_each_sched_rt_entity(rt_se
) {
913 rt_rq
= rt_rq_of_se(rt_se
);
915 if (sched_rt_runtime(rt_rq
) != RUNTIME_INF
) {
916 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
917 rt_rq
->rt_time
+= delta_exec
;
918 if (sched_rt_runtime_exceeded(rt_rq
))
920 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
925 #if defined CONFIG_SMP
928 inc_rt_prio_smp(struct rt_rq
*rt_rq
, int prio
, int prev_prio
)
930 struct rq
*rq
= rq_of_rt_rq(rt_rq
);
932 #ifdef CONFIG_RT_GROUP_SCHED
934 * Change rq's cpupri only if rt_rq is the top queue.
936 if (&rq
->rt
!= rt_rq
)
939 if (rq
->online
&& prio
< prev_prio
)
940 cpupri_set(&rq
->rd
->cpupri
, rq
->cpu
, prio
);
944 dec_rt_prio_smp(struct rt_rq
*rt_rq
, int prio
, int prev_prio
)
946 struct rq
*rq
= rq_of_rt_rq(rt_rq
);
948 #ifdef CONFIG_RT_GROUP_SCHED
950 * Change rq's cpupri only if rt_rq is the top queue.
952 if (&rq
->rt
!= rt_rq
)
955 if (rq
->online
&& rt_rq
->highest_prio
.curr
!= prev_prio
)
956 cpupri_set(&rq
->rd
->cpupri
, rq
->cpu
, rt_rq
->highest_prio
.curr
);
959 #else /* CONFIG_SMP */
962 void inc_rt_prio_smp(struct rt_rq
*rt_rq
, int prio
, int prev_prio
) {}
964 void dec_rt_prio_smp(struct rt_rq
*rt_rq
, int prio
, int prev_prio
) {}
966 #endif /* CONFIG_SMP */
968 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
970 inc_rt_prio(struct rt_rq
*rt_rq
, int prio
)
972 int prev_prio
= rt_rq
->highest_prio
.curr
;
974 if (prio
< prev_prio
)
975 rt_rq
->highest_prio
.curr
= prio
;
977 inc_rt_prio_smp(rt_rq
, prio
, prev_prio
);
981 dec_rt_prio(struct rt_rq
*rt_rq
, int prio
)
983 int prev_prio
= rt_rq
->highest_prio
.curr
;
985 if (rt_rq
->rt_nr_running
) {
987 WARN_ON(prio
< prev_prio
);
990 * This may have been our highest task, and therefore
991 * we may have some recomputation to do
993 if (prio
== prev_prio
) {
994 struct rt_prio_array
*array
= &rt_rq
->active
;
996 rt_rq
->highest_prio
.curr
=
997 sched_find_first_bit(array
->bitmap
);
1001 rt_rq
->highest_prio
.curr
= MAX_RT_PRIO
;
1003 dec_rt_prio_smp(rt_rq
, prio
, prev_prio
);
1008 static inline void inc_rt_prio(struct rt_rq
*rt_rq
, int prio
) {}
1009 static inline void dec_rt_prio(struct rt_rq
*rt_rq
, int prio
) {}
1011 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
1013 #ifdef CONFIG_RT_GROUP_SCHED
1016 inc_rt_group(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
)
1018 if (rt_se_boosted(rt_se
))
1019 rt_rq
->rt_nr_boosted
++;
1022 start_rt_bandwidth(&rt_rq
->tg
->rt_bandwidth
);
1026 dec_rt_group(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
)
1028 if (rt_se_boosted(rt_se
))
1029 rt_rq
->rt_nr_boosted
--;
1031 WARN_ON(!rt_rq
->rt_nr_running
&& rt_rq
->rt_nr_boosted
);
1034 #else /* CONFIG_RT_GROUP_SCHED */
1037 inc_rt_group(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
)
1039 start_rt_bandwidth(&def_rt_bandwidth
);
1043 void dec_rt_group(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
) {}
1045 #endif /* CONFIG_RT_GROUP_SCHED */
1048 void inc_rt_tasks(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
)
1050 int prio
= rt_se_prio(rt_se
);
1052 WARN_ON(!rt_prio(prio
));
1053 rt_rq
->rt_nr_running
++;
1055 inc_rt_prio(rt_rq
, prio
);
1056 inc_rt_migration(rt_se
, rt_rq
);
1057 inc_rt_group(rt_se
, rt_rq
);
1061 void dec_rt_tasks(struct sched_rt_entity
*rt_se
, struct rt_rq
*rt_rq
)
1063 WARN_ON(!rt_prio(rt_se_prio(rt_se
)));
1064 WARN_ON(!rt_rq
->rt_nr_running
);
1065 rt_rq
->rt_nr_running
--;
1067 dec_rt_prio(rt_rq
, rt_se_prio(rt_se
));
1068 dec_rt_migration(rt_se
, rt_rq
);
1069 dec_rt_group(rt_se
, rt_rq
);
1072 static void __enqueue_rt_entity(struct sched_rt_entity
*rt_se
, bool head
)
1074 struct rt_rq
*rt_rq
= rt_rq_of_se(rt_se
);
1075 struct rt_prio_array
*array
= &rt_rq
->active
;
1076 struct rt_rq
*group_rq
= group_rt_rq(rt_se
);
1077 struct list_head
*queue
= array
->queue
+ rt_se_prio(rt_se
);
1080 * Don't enqueue the group if its throttled, or when empty.
1081 * The latter is a consequence of the former when a child group
1082 * get throttled and the current group doesn't have any other
1085 if (group_rq
&& (rt_rq_throttled(group_rq
) || !group_rq
->rt_nr_running
))
1089 list_add(&rt_se
->run_list
, queue
);
1091 list_add_tail(&rt_se
->run_list
, queue
);
1092 __set_bit(rt_se_prio(rt_se
), array
->bitmap
);
1094 inc_rt_tasks(rt_se
, rt_rq
);
1097 static void __dequeue_rt_entity(struct sched_rt_entity
*rt_se
)
1099 struct rt_rq
*rt_rq
= rt_rq_of_se(rt_se
);
1100 struct rt_prio_array
*array
= &rt_rq
->active
;
1102 list_del_init(&rt_se
->run_list
);
1103 if (list_empty(array
->queue
+ rt_se_prio(rt_se
)))
1104 __clear_bit(rt_se_prio(rt_se
), array
->bitmap
);
1106 dec_rt_tasks(rt_se
, rt_rq
);
1110 * Because the prio of an upper entry depends on the lower
1111 * entries, we must remove entries top - down.
1113 static void dequeue_rt_stack(struct sched_rt_entity
*rt_se
)
1115 struct sched_rt_entity
*back
= NULL
;
1117 for_each_sched_rt_entity(rt_se
) {
1122 for (rt_se
= back
; rt_se
; rt_se
= rt_se
->back
) {
1123 if (on_rt_rq(rt_se
))
1124 __dequeue_rt_entity(rt_se
);
1128 static void enqueue_rt_entity(struct sched_rt_entity
*rt_se
, bool head
)
1130 dequeue_rt_stack(rt_se
);
1131 for_each_sched_rt_entity(rt_se
)
1132 __enqueue_rt_entity(rt_se
, head
);
1135 static void dequeue_rt_entity(struct sched_rt_entity
*rt_se
)
1137 dequeue_rt_stack(rt_se
);
1139 for_each_sched_rt_entity(rt_se
) {
1140 struct rt_rq
*rt_rq
= group_rt_rq(rt_se
);
1142 if (rt_rq
&& rt_rq
->rt_nr_running
)
1143 __enqueue_rt_entity(rt_se
, false);
1148 * Adding/removing a task to/from a priority array:
1151 enqueue_task_rt(struct rq
*rq
, struct task_struct
*p
, int flags
)
1153 struct sched_rt_entity
*rt_se
= &p
->rt
;
1155 if (flags
& ENQUEUE_WAKEUP
)
1158 enqueue_rt_entity(rt_se
, flags
& ENQUEUE_HEAD
);
1160 if (!task_current(rq
, p
) && p
->nr_cpus_allowed
> 1)
1161 enqueue_pushable_task(rq
, p
);
1166 static void dequeue_task_rt(struct rq
*rq
, struct task_struct
*p
, int flags
)
1168 struct sched_rt_entity
*rt_se
= &p
->rt
;
1171 dequeue_rt_entity(rt_se
);
1173 dequeue_pushable_task(rq
, p
);
1179 * Put task to the head or the end of the run list without the overhead of
1180 * dequeue followed by enqueue.
1183 requeue_rt_entity(struct rt_rq
*rt_rq
, struct sched_rt_entity
*rt_se
, int head
)
1185 if (on_rt_rq(rt_se
)) {
1186 struct rt_prio_array
*array
= &rt_rq
->active
;
1187 struct list_head
*queue
= array
->queue
+ rt_se_prio(rt_se
);
1190 list_move(&rt_se
->run_list
, queue
);
1192 list_move_tail(&rt_se
->run_list
, queue
);
1196 static void requeue_task_rt(struct rq
*rq
, struct task_struct
*p
, int head
)
1198 struct sched_rt_entity
*rt_se
= &p
->rt
;
1199 struct rt_rq
*rt_rq
;
1201 for_each_sched_rt_entity(rt_se
) {
1202 rt_rq
= rt_rq_of_se(rt_se
);
1203 requeue_rt_entity(rt_rq
, rt_se
, head
);
1207 static void yield_task_rt(struct rq
*rq
)
1209 requeue_task_rt(rq
, rq
->curr
, 0);
1213 static int find_lowest_rq(struct task_struct
*task
);
1216 select_task_rq_rt(struct task_struct
*p
, int cpu
, int sd_flag
, int flags
)
1218 struct task_struct
*curr
;
1221 if (p
->nr_cpus_allowed
== 1)
1224 /* For anything but wake ups, just return the task_cpu */
1225 if (sd_flag
!= SD_BALANCE_WAKE
&& sd_flag
!= SD_BALANCE_FORK
)
1231 curr
= ACCESS_ONCE(rq
->curr
); /* unlocked access */
1234 * If the current task on @p's runqueue is an RT task, then
1235 * try to see if we can wake this RT task up on another
1236 * runqueue. Otherwise simply start this RT task
1237 * on its current runqueue.
1239 * We want to avoid overloading runqueues. If the woken
1240 * task is a higher priority, then it will stay on this CPU
1241 * and the lower prio task should be moved to another CPU.
1242 * Even though this will probably make the lower prio task
1243 * lose its cache, we do not want to bounce a higher task
1244 * around just because it gave up its CPU, perhaps for a
1247 * For equal prio tasks, we just let the scheduler sort it out.
1249 * Otherwise, just let it ride on the affined RQ and the
1250 * post-schedule router will push the preempted task away
1252 * This test is optimistic, if we get it wrong the load-balancer
1253 * will have to sort it out.
1255 if (curr
&& unlikely(rt_task(curr
)) &&
1256 (curr
->nr_cpus_allowed
< 2 ||
1257 curr
->prio
<= p
->prio
)) {
1258 int target
= find_lowest_rq(p
);
1269 static void check_preempt_equal_prio(struct rq
*rq
, struct task_struct
*p
)
1271 if (rq
->curr
->nr_cpus_allowed
== 1)
1274 if (p
->nr_cpus_allowed
!= 1
1275 && cpupri_find(&rq
->rd
->cpupri
, p
, NULL
))
1278 if (!cpupri_find(&rq
->rd
->cpupri
, rq
->curr
, NULL
))
1282 * There appears to be other cpus that can accept
1283 * current and none to run 'p', so lets reschedule
1284 * to try and push current away:
1286 requeue_task_rt(rq
, p
, 1);
1287 resched_task(rq
->curr
);
1290 #endif /* CONFIG_SMP */
1293 * Preempt the current task with a newly woken task if needed:
1295 static void check_preempt_curr_rt(struct rq
*rq
, struct task_struct
*p
, int flags
)
1297 if (p
->prio
< rq
->curr
->prio
) {
1298 resched_task(rq
->curr
);
1306 * - the newly woken task is of equal priority to the current task
1307 * - the newly woken task is non-migratable while current is migratable
1308 * - current will be preempted on the next reschedule
1310 * we should check to see if current can readily move to a different
1311 * cpu. If so, we will reschedule to allow the push logic to try
1312 * to move current somewhere else, making room for our non-migratable
1315 if (p
->prio
== rq
->curr
->prio
&& !test_tsk_need_resched(rq
->curr
))
1316 check_preempt_equal_prio(rq
, p
);
1320 static struct sched_rt_entity
*pick_next_rt_entity(struct rq
*rq
,
1321 struct rt_rq
*rt_rq
)
1323 struct rt_prio_array
*array
= &rt_rq
->active
;
1324 struct sched_rt_entity
*next
= NULL
;
1325 struct list_head
*queue
;
1328 idx
= sched_find_first_bit(array
->bitmap
);
1329 BUG_ON(idx
>= MAX_RT_PRIO
);
1331 queue
= array
->queue
+ idx
;
1332 next
= list_entry(queue
->next
, struct sched_rt_entity
, run_list
);
1337 static struct task_struct
*_pick_next_task_rt(struct rq
*rq
)
1339 struct sched_rt_entity
*rt_se
;
1340 struct task_struct
*p
;
1341 struct rt_rq
*rt_rq
= &rq
->rt
;
1344 rt_se
= pick_next_rt_entity(rq
, rt_rq
);
1346 rt_rq
= group_rt_rq(rt_se
);
1349 p
= rt_task_of(rt_se
);
1350 p
->se
.exec_start
= rq_clock_task(rq
);
1355 static struct task_struct
*
1356 pick_next_task_rt(struct rq
*rq
, struct task_struct
*prev
)
1358 struct task_struct
*p
;
1359 struct rt_rq
*rt_rq
= &rq
->rt
;
1361 if (need_pull_rt_task(rq
, prev
)) {
1364 * pull_rt_task() can drop (and re-acquire) rq->lock; this
1365 * means a dl task can slip in, in which case we need to
1366 * re-start task selection.
1368 if (unlikely(rq
->dl
.dl_nr_running
))
1373 * We may dequeue prev's rt_rq in put_prev_task().
1374 * So, we update time before rt_nr_running check.
1376 if (prev
->sched_class
== &rt_sched_class
)
1379 if (!rt_rq
->rt_nr_running
)
1382 if (rt_rq_throttled(rt_rq
))
1385 put_prev_task(rq
, prev
);
1387 p
= _pick_next_task_rt(rq
);
1389 /* The running task is never eligible for pushing */
1391 dequeue_pushable_task(rq
, p
);
1393 set_post_schedule(rq
);
1398 static void put_prev_task_rt(struct rq
*rq
, struct task_struct
*p
)
1403 * The previous task needs to be made eligible for pushing
1404 * if it is still active
1406 if (on_rt_rq(&p
->rt
) && p
->nr_cpus_allowed
> 1)
1407 enqueue_pushable_task(rq
, p
);
1412 /* Only try algorithms three times */
1413 #define RT_MAX_TRIES 3
1415 static int pick_rt_task(struct rq
*rq
, struct task_struct
*p
, int cpu
)
1417 if (!task_running(rq
, p
) &&
1418 cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
)))
1424 * Return the highest pushable rq's task, which is suitable to be executed
1425 * on the cpu, NULL otherwise
1427 static struct task_struct
*pick_highest_pushable_task(struct rq
*rq
, int cpu
)
1429 struct plist_head
*head
= &rq
->rt
.pushable_tasks
;
1430 struct task_struct
*p
;
1432 if (!has_pushable_tasks(rq
))
1435 plist_for_each_entry(p
, head
, pushable_tasks
) {
1436 if (pick_rt_task(rq
, p
, cpu
))
1443 static DEFINE_PER_CPU(cpumask_var_t
, local_cpu_mask
);
1445 static int find_lowest_rq(struct task_struct
*task
)
1447 struct sched_domain
*sd
;
1448 struct cpumask
*lowest_mask
= __get_cpu_var(local_cpu_mask
);
1449 int this_cpu
= smp_processor_id();
1450 int cpu
= task_cpu(task
);
1452 /* Make sure the mask is initialized first */
1453 if (unlikely(!lowest_mask
))
1456 if (task
->nr_cpus_allowed
== 1)
1457 return -1; /* No other targets possible */
1459 if (!cpupri_find(&task_rq(task
)->rd
->cpupri
, task
, lowest_mask
))
1460 return -1; /* No targets found */
1463 * At this point we have built a mask of cpus representing the
1464 * lowest priority tasks in the system. Now we want to elect
1465 * the best one based on our affinity and topology.
1467 * We prioritize the last cpu that the task executed on since
1468 * it is most likely cache-hot in that location.
1470 if (cpumask_test_cpu(cpu
, lowest_mask
))
1474 * Otherwise, we consult the sched_domains span maps to figure
1475 * out which cpu is logically closest to our hot cache data.
1477 if (!cpumask_test_cpu(this_cpu
, lowest_mask
))
1478 this_cpu
= -1; /* Skip this_cpu opt if not among lowest */
1481 for_each_domain(cpu
, sd
) {
1482 if (sd
->flags
& SD_WAKE_AFFINE
) {
1486 * "this_cpu" is cheaper to preempt than a
1489 if (this_cpu
!= -1 &&
1490 cpumask_test_cpu(this_cpu
, sched_domain_span(sd
))) {
1495 best_cpu
= cpumask_first_and(lowest_mask
,
1496 sched_domain_span(sd
));
1497 if (best_cpu
< nr_cpu_ids
) {
1506 * And finally, if there were no matches within the domains
1507 * just give the caller *something* to work with from the compatible
1513 cpu
= cpumask_any(lowest_mask
);
1514 if (cpu
< nr_cpu_ids
)
1519 /* Will lock the rq it finds */
1520 static struct rq
*find_lock_lowest_rq(struct task_struct
*task
, struct rq
*rq
)
1522 struct rq
*lowest_rq
= NULL
;
1526 for (tries
= 0; tries
< RT_MAX_TRIES
; tries
++) {
1527 cpu
= find_lowest_rq(task
);
1529 if ((cpu
== -1) || (cpu
== rq
->cpu
))
1532 lowest_rq
= cpu_rq(cpu
);
1534 /* if the prio of this runqueue changed, try again */
1535 if (double_lock_balance(rq
, lowest_rq
)) {
1537 * We had to unlock the run queue. In
1538 * the mean time, task could have
1539 * migrated already or had its affinity changed.
1540 * Also make sure that it wasn't scheduled on its rq.
1542 if (unlikely(task_rq(task
) != rq
||
1543 !cpumask_test_cpu(lowest_rq
->cpu
,
1544 tsk_cpus_allowed(task
)) ||
1545 task_running(rq
, task
) ||
1548 double_unlock_balance(rq
, lowest_rq
);
1554 /* If this rq is still suitable use it. */
1555 if (lowest_rq
->rt
.highest_prio
.curr
> task
->prio
)
1559 double_unlock_balance(rq
, lowest_rq
);
1566 static struct task_struct
*pick_next_pushable_task(struct rq
*rq
)
1568 struct task_struct
*p
;
1570 if (!has_pushable_tasks(rq
))
1573 p
= plist_first_entry(&rq
->rt
.pushable_tasks
,
1574 struct task_struct
, pushable_tasks
);
1576 BUG_ON(rq
->cpu
!= task_cpu(p
));
1577 BUG_ON(task_current(rq
, p
));
1578 BUG_ON(p
->nr_cpus_allowed
<= 1);
1581 BUG_ON(!rt_task(p
));
1587 * If the current CPU has more than one RT task, see if the non
1588 * running task can migrate over to a CPU that is running a task
1589 * of lesser priority.
1591 static int push_rt_task(struct rq
*rq
)
1593 struct task_struct
*next_task
;
1594 struct rq
*lowest_rq
;
1597 if (!rq
->rt
.overloaded
)
1600 next_task
= pick_next_pushable_task(rq
);
1605 if (unlikely(next_task
== rq
->curr
)) {
1611 * It's possible that the next_task slipped in of
1612 * higher priority than current. If that's the case
1613 * just reschedule current.
1615 if (unlikely(next_task
->prio
< rq
->curr
->prio
)) {
1616 resched_task(rq
->curr
);
1620 /* We might release rq lock */
1621 get_task_struct(next_task
);
1623 /* find_lock_lowest_rq locks the rq if found */
1624 lowest_rq
= find_lock_lowest_rq(next_task
, rq
);
1626 struct task_struct
*task
;
1628 * find_lock_lowest_rq releases rq->lock
1629 * so it is possible that next_task has migrated.
1631 * We need to make sure that the task is still on the same
1632 * run-queue and is also still the next task eligible for
1635 task
= pick_next_pushable_task(rq
);
1636 if (task_cpu(next_task
) == rq
->cpu
&& task
== next_task
) {
1638 * The task hasn't migrated, and is still the next
1639 * eligible task, but we failed to find a run-queue
1640 * to push it to. Do not retry in this case, since
1641 * other cpus will pull from us when ready.
1647 /* No more tasks, just exit */
1651 * Something has shifted, try again.
1653 put_task_struct(next_task
);
1658 deactivate_task(rq
, next_task
, 0);
1659 set_task_cpu(next_task
, lowest_rq
->cpu
);
1660 activate_task(lowest_rq
, next_task
, 0);
1663 resched_task(lowest_rq
->curr
);
1665 double_unlock_balance(rq
, lowest_rq
);
1668 put_task_struct(next_task
);
1673 static void push_rt_tasks(struct rq
*rq
)
1675 /* push_rt_task will return true if it moved an RT */
1676 while (push_rt_task(rq
))
1680 static int pull_rt_task(struct rq
*this_rq
)
1682 int this_cpu
= this_rq
->cpu
, ret
= 0, cpu
;
1683 struct task_struct
*p
;
1686 if (likely(!rt_overloaded(this_rq
)))
1690 * Match the barrier from rt_set_overloaded; this guarantees that if we
1691 * see overloaded we must also see the rto_mask bit.
1695 for_each_cpu(cpu
, this_rq
->rd
->rto_mask
) {
1696 if (this_cpu
== cpu
)
1699 src_rq
= cpu_rq(cpu
);
1702 * Don't bother taking the src_rq->lock if the next highest
1703 * task is known to be lower-priority than our current task.
1704 * This may look racy, but if this value is about to go
1705 * logically higher, the src_rq will push this task away.
1706 * And if its going logically lower, we do not care
1708 if (src_rq
->rt
.highest_prio
.next
>=
1709 this_rq
->rt
.highest_prio
.curr
)
1713 * We can potentially drop this_rq's lock in
1714 * double_lock_balance, and another CPU could
1717 double_lock_balance(this_rq
, src_rq
);
1720 * We can pull only a task, which is pushable
1721 * on its rq, and no others.
1723 p
= pick_highest_pushable_task(src_rq
, this_cpu
);
1726 * Do we have an RT task that preempts
1727 * the to-be-scheduled task?
1729 if (p
&& (p
->prio
< this_rq
->rt
.highest_prio
.curr
)) {
1730 WARN_ON(p
== src_rq
->curr
);
1734 * There's a chance that p is higher in priority
1735 * than what's currently running on its cpu.
1736 * This is just that p is wakeing up and hasn't
1737 * had a chance to schedule. We only pull
1738 * p if it is lower in priority than the
1739 * current task on the run queue
1741 if (p
->prio
< src_rq
->curr
->prio
)
1746 deactivate_task(src_rq
, p
, 0);
1747 set_task_cpu(p
, this_cpu
);
1748 activate_task(this_rq
, p
, 0);
1750 * We continue with the search, just in
1751 * case there's an even higher prio task
1752 * in another runqueue. (low likelihood
1757 double_unlock_balance(this_rq
, src_rq
);
1763 static void post_schedule_rt(struct rq
*rq
)
1769 * If we are not running and we are not going to reschedule soon, we should
1770 * try to push tasks away now
1772 static void task_woken_rt(struct rq
*rq
, struct task_struct
*p
)
1774 if (!task_running(rq
, p
) &&
1775 !test_tsk_need_resched(rq
->curr
) &&
1776 has_pushable_tasks(rq
) &&
1777 p
->nr_cpus_allowed
> 1 &&
1778 (dl_task(rq
->curr
) || rt_task(rq
->curr
)) &&
1779 (rq
->curr
->nr_cpus_allowed
< 2 ||
1780 rq
->curr
->prio
<= p
->prio
))
1784 static void set_cpus_allowed_rt(struct task_struct
*p
,
1785 const struct cpumask
*new_mask
)
1790 BUG_ON(!rt_task(p
));
1795 weight
= cpumask_weight(new_mask
);
1798 * Only update if the process changes its state from whether it
1799 * can migrate or not.
1801 if ((p
->nr_cpus_allowed
> 1) == (weight
> 1))
1807 * The process used to be able to migrate OR it can now migrate
1810 if (!task_current(rq
, p
))
1811 dequeue_pushable_task(rq
, p
);
1812 BUG_ON(!rq
->rt
.rt_nr_migratory
);
1813 rq
->rt
.rt_nr_migratory
--;
1815 if (!task_current(rq
, p
))
1816 enqueue_pushable_task(rq
, p
);
1817 rq
->rt
.rt_nr_migratory
++;
1820 update_rt_migration(&rq
->rt
);
1823 /* Assumes rq->lock is held */
1824 static void rq_online_rt(struct rq
*rq
)
1826 if (rq
->rt
.overloaded
)
1827 rt_set_overload(rq
);
1829 __enable_runtime(rq
);
1831 cpupri_set(&rq
->rd
->cpupri
, rq
->cpu
, rq
->rt
.highest_prio
.curr
);
1834 /* Assumes rq->lock is held */
1835 static void rq_offline_rt(struct rq
*rq
)
1837 if (rq
->rt
.overloaded
)
1838 rt_clear_overload(rq
);
1840 __disable_runtime(rq
);
1842 cpupri_set(&rq
->rd
->cpupri
, rq
->cpu
, CPUPRI_INVALID
);
1846 * When switch from the rt queue, we bring ourselves to a position
1847 * that we might want to pull RT tasks from other runqueues.
1849 static void switched_from_rt(struct rq
*rq
, struct task_struct
*p
)
1852 * If there are other RT tasks then we will reschedule
1853 * and the scheduling of the other RT tasks will handle
1854 * the balancing. But if we are the last RT task
1855 * we may need to handle the pulling of RT tasks
1858 if (!p
->on_rq
|| rq
->rt
.rt_nr_running
)
1861 if (pull_rt_task(rq
))
1862 resched_task(rq
->curr
);
1865 void __init
init_sched_rt_class(void)
1869 for_each_possible_cpu(i
) {
1870 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask
, i
),
1871 GFP_KERNEL
, cpu_to_node(i
));
1874 #endif /* CONFIG_SMP */
1877 * When switching a task to RT, we may overload the runqueue
1878 * with RT tasks. In this case we try to push them off to
1881 static void switched_to_rt(struct rq
*rq
, struct task_struct
*p
)
1883 int check_resched
= 1;
1886 * If we are already running, then there's nothing
1887 * that needs to be done. But if we are not running
1888 * we may need to preempt the current running task.
1889 * If that current running task is also an RT task
1890 * then see if we can move to another run queue.
1892 if (p
->on_rq
&& rq
->curr
!= p
) {
1894 if (rq
->rt
.overloaded
&& push_rt_task(rq
) &&
1895 /* Don't resched if we changed runqueues */
1898 #endif /* CONFIG_SMP */
1899 if (check_resched
&& p
->prio
< rq
->curr
->prio
)
1900 resched_task(rq
->curr
);
1905 * Priority of the task has changed. This may cause
1906 * us to initiate a push or pull.
1909 prio_changed_rt(struct rq
*rq
, struct task_struct
*p
, int oldprio
)
1914 if (rq
->curr
== p
) {
1917 * If our priority decreases while running, we
1918 * may need to pull tasks to this runqueue.
1920 if (oldprio
< p
->prio
)
1923 * If there's a higher priority task waiting to run
1924 * then reschedule. Note, the above pull_rt_task
1925 * can release the rq lock and p could migrate.
1926 * Only reschedule if p is still on the same runqueue.
1928 if (p
->prio
> rq
->rt
.highest_prio
.curr
&& rq
->curr
== p
)
1931 /* For UP simply resched on drop of prio */
1932 if (oldprio
< p
->prio
)
1934 #endif /* CONFIG_SMP */
1937 * This task is not running, but if it is
1938 * greater than the current running task
1941 if (p
->prio
< rq
->curr
->prio
)
1942 resched_task(rq
->curr
);
1946 static void watchdog(struct rq
*rq
, struct task_struct
*p
)
1948 unsigned long soft
, hard
;
1950 /* max may change after cur was read, this will be fixed next tick */
1951 soft
= task_rlimit(p
, RLIMIT_RTTIME
);
1952 hard
= task_rlimit_max(p
, RLIMIT_RTTIME
);
1954 if (soft
!= RLIM_INFINITY
) {
1957 if (p
->rt
.watchdog_stamp
!= jiffies
) {
1959 p
->rt
.watchdog_stamp
= jiffies
;
1962 next
= DIV_ROUND_UP(min(soft
, hard
), USEC_PER_SEC
/HZ
);
1963 if (p
->rt
.timeout
> next
)
1964 p
->cputime_expires
.sched_exp
= p
->se
.sum_exec_runtime
;
1968 static void task_tick_rt(struct rq
*rq
, struct task_struct
*p
, int queued
)
1970 struct sched_rt_entity
*rt_se
= &p
->rt
;
1977 * RR tasks need a special form of timeslice management.
1978 * FIFO tasks have no timeslices.
1980 if (p
->policy
!= SCHED_RR
)
1983 if (--p
->rt
.time_slice
)
1986 p
->rt
.time_slice
= sched_rr_timeslice
;
1989 * Requeue to the end of queue if we (and all of our ancestors) are not
1990 * the only element on the queue
1992 for_each_sched_rt_entity(rt_se
) {
1993 if (rt_se
->run_list
.prev
!= rt_se
->run_list
.next
) {
1994 requeue_task_rt(rq
, p
, 0);
1995 set_tsk_need_resched(p
);
2001 static void set_curr_task_rt(struct rq
*rq
)
2003 struct task_struct
*p
= rq
->curr
;
2005 p
->se
.exec_start
= rq_clock_task(rq
);
2007 /* The running task is never eligible for pushing */
2008 dequeue_pushable_task(rq
, p
);
2011 static unsigned int get_rr_interval_rt(struct rq
*rq
, struct task_struct
*task
)
2014 * Time slice is 0 for SCHED_FIFO tasks
2016 if (task
->policy
== SCHED_RR
)
2017 return sched_rr_timeslice
;
2022 const struct sched_class rt_sched_class
= {
2023 .next
= &fair_sched_class
,
2024 .enqueue_task
= enqueue_task_rt
,
2025 .dequeue_task
= dequeue_task_rt
,
2026 .yield_task
= yield_task_rt
,
2028 .check_preempt_curr
= check_preempt_curr_rt
,
2030 .pick_next_task
= pick_next_task_rt
,
2031 .put_prev_task
= put_prev_task_rt
,
2034 .select_task_rq
= select_task_rq_rt
,
2036 .set_cpus_allowed
= set_cpus_allowed_rt
,
2037 .rq_online
= rq_online_rt
,
2038 .rq_offline
= rq_offline_rt
,
2039 .post_schedule
= post_schedule_rt
,
2040 .task_woken
= task_woken_rt
,
2041 .switched_from
= switched_from_rt
,
2044 .set_curr_task
= set_curr_task_rt
,
2045 .task_tick
= task_tick_rt
,
2047 .get_rr_interval
= get_rr_interval_rt
,
2049 .prio_changed
= prio_changed_rt
,
2050 .switched_to
= switched_to_rt
,
2053 #ifdef CONFIG_SCHED_DEBUG
2054 extern void print_rt_rq(struct seq_file
*m
, int cpu
, struct rt_rq
*rt_rq
);
2056 void print_rt_stats(struct seq_file
*m
, int cpu
)
2059 struct rt_rq
*rt_rq
;
2062 for_each_rt_rq(rt_rq
, iter
, cpu_rq(cpu
))
2063 print_rt_rq(m
, cpu
, rt_rq
);
2066 #endif /* CONFIG_SCHED_DEBUG */