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1/*
2 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
3 * policies)
4 */
5
6#ifdef CONFIG_RT_GROUP_SCHED
7
8#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
9
10static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
11{
12#ifdef CONFIG_SCHED_DEBUG
13 WARN_ON_ONCE(!rt_entity_is_task(rt_se));
14#endif
15 return container_of(rt_se, struct task_struct, rt);
16}
17
18static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
19{
20 return rt_rq->rq;
21}
22
23static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
24{
25 return rt_se->rt_rq;
26}
27
28#else /* CONFIG_RT_GROUP_SCHED */
29
30#define rt_entity_is_task(rt_se) (1)
31
32static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
33{
34 return container_of(rt_se, struct task_struct, rt);
35}
36
37static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
38{
39 return container_of(rt_rq, struct rq, rt);
40}
41
42static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
43{
44 struct task_struct *p = rt_task_of(rt_se);
45 struct rq *rq = task_rq(p);
46
47 return &rq->rt;
48}
49
50#endif /* CONFIG_RT_GROUP_SCHED */
51
52#ifdef CONFIG_SMP
53
54static inline int rt_overloaded(struct rq *rq)
55{
56 return atomic_read(&rq->rd->rto_count);
57}
58
59static inline void rt_set_overload(struct rq *rq)
60{
61 if (!rq->online)
62 return;
63
64 cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
65 /*
66 * Make sure the mask is visible before we set
67 * the overload count. That is checked to determine
68 * if we should look at the mask. It would be a shame
69 * if we looked at the mask, but the mask was not
70 * updated yet.
71 */
72 wmb();
73 atomic_inc(&rq->rd->rto_count);
74}
75
76static inline void rt_clear_overload(struct rq *rq)
77{
78 if (!rq->online)
79 return;
80
81 /* the order here really doesn't matter */
82 atomic_dec(&rq->rd->rto_count);
83 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
84}
85
86static void update_rt_migration(struct rt_rq *rt_rq)
87{
88 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
89 if (!rt_rq->overloaded) {
90 rt_set_overload(rq_of_rt_rq(rt_rq));
91 rt_rq->overloaded = 1;
92 }
93 } else if (rt_rq->overloaded) {
94 rt_clear_overload(rq_of_rt_rq(rt_rq));
95 rt_rq->overloaded = 0;
96 }
97}
98
99static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
100{
101 if (!rt_entity_is_task(rt_se))
102 return;
103
104 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
105
106 rt_rq->rt_nr_total++;
107 if (rt_se->nr_cpus_allowed > 1)
108 rt_rq->rt_nr_migratory++;
109
110 update_rt_migration(rt_rq);
111}
112
113static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
114{
115 if (!rt_entity_is_task(rt_se))
116 return;
117
118 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
119
120 rt_rq->rt_nr_total--;
121 if (rt_se->nr_cpus_allowed > 1)
122 rt_rq->rt_nr_migratory--;
123
124 update_rt_migration(rt_rq);
125}
126
127static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
128{
129 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
130 plist_node_init(&p->pushable_tasks, p->prio);
131 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
132}
133
134static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
135{
136 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
137}
138
139static inline int has_pushable_tasks(struct rq *rq)
140{
141 return !plist_head_empty(&rq->rt.pushable_tasks);
142}
143
144#else
145
146static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
147{
148}
149
150static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
151{
152}
153
154static inline
155void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
156{
157}
158
159static inline
160void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
161{
162}
163
164#endif /* CONFIG_SMP */
165
166static inline int on_rt_rq(struct sched_rt_entity *rt_se)
167{
168 return !list_empty(&rt_se->run_list);
169}
170
171#ifdef CONFIG_RT_GROUP_SCHED
172
173static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
174{
175 if (!rt_rq->tg)
176 return RUNTIME_INF;
177
178 return rt_rq->rt_runtime;
179}
180
181static inline u64 sched_rt_period(struct rt_rq *rt_rq)
182{
183 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
184}
185
186static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
187{
188 list_add_rcu(&rt_rq->leaf_rt_rq_list,
189 &rq_of_rt_rq(rt_rq)->leaf_rt_rq_list);
190}
191
192static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
193{
194 list_del_rcu(&rt_rq->leaf_rt_rq_list);
195}
196
197#define for_each_leaf_rt_rq(rt_rq, rq) \
198 list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
199
200#define for_each_sched_rt_entity(rt_se) \
201 for (; rt_se; rt_se = rt_se->parent)
202
203static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
204{
205 return rt_se->my_q;
206}
207
208static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
209static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
210
211static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
212{
213 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
214 struct sched_rt_entity *rt_se;
215
216 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
217
218 rt_se = rt_rq->tg->rt_se[cpu];
219
220 if (rt_rq->rt_nr_running) {
221 if (rt_se && !on_rt_rq(rt_se))
222 enqueue_rt_entity(rt_se, false);
223 if (rt_rq->highest_prio.curr < curr->prio)
224 resched_task(curr);
225 }
226}
227
228static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
229{
230 struct sched_rt_entity *rt_se;
231 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
232
233 rt_se = rt_rq->tg->rt_se[cpu];
234
235 if (rt_se && on_rt_rq(rt_se))
236 dequeue_rt_entity(rt_se);
237}
238
239static inline int rt_rq_throttled(struct rt_rq *rt_rq)
240{
241 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
242}
243
244static int rt_se_boosted(struct sched_rt_entity *rt_se)
245{
246 struct rt_rq *rt_rq = group_rt_rq(rt_se);
247 struct task_struct *p;
248
249 if (rt_rq)
250 return !!rt_rq->rt_nr_boosted;
251
252 p = rt_task_of(rt_se);
253 return p->prio != p->normal_prio;
254}
255
256#ifdef CONFIG_SMP
257static inline const struct cpumask *sched_rt_period_mask(void)
258{
259 return cpu_rq(smp_processor_id())->rd->span;
260}
261#else
262static inline const struct cpumask *sched_rt_period_mask(void)
263{
264 return cpu_online_mask;
265}
266#endif
267
268static inline
269struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
270{
271 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
272}
273
274static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
275{
276 return &rt_rq->tg->rt_bandwidth;
277}
278
279#else /* !CONFIG_RT_GROUP_SCHED */
280
281static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
282{
283 return rt_rq->rt_runtime;
284}
285
286static inline u64 sched_rt_period(struct rt_rq *rt_rq)
287{
288 return ktime_to_ns(def_rt_bandwidth.rt_period);
289}
290
291static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
292{
293}
294
295static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
296{
297}
298
299#define for_each_leaf_rt_rq(rt_rq, rq) \
300 for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
301
302#define for_each_sched_rt_entity(rt_se) \
303 for (; rt_se; rt_se = NULL)
304
305static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
306{
307 return NULL;
308}
309
310static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
311{
312 if (rt_rq->rt_nr_running)
313 resched_task(rq_of_rt_rq(rt_rq)->curr);
314}
315
316static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
317{
318}
319
320static inline int rt_rq_throttled(struct rt_rq *rt_rq)
321{
322 return rt_rq->rt_throttled;
323}
324
325static inline const struct cpumask *sched_rt_period_mask(void)
326{
327 return cpu_online_mask;
328}
329
330static inline
331struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
332{
333 return &cpu_rq(cpu)->rt;
334}
335
336static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
337{
338 return &def_rt_bandwidth;
339}
340
341#endif /* CONFIG_RT_GROUP_SCHED */
342
343#ifdef CONFIG_SMP
344/*
345 * We ran out of runtime, see if we can borrow some from our neighbours.
346 */
347static int do_balance_runtime(struct rt_rq *rt_rq)
348{
349 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
350 struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
351 int i, weight, more = 0;
352 u64 rt_period;
353
354 weight = cpumask_weight(rd->span);
355
356 raw_spin_lock(&rt_b->rt_runtime_lock);
357 rt_period = ktime_to_ns(rt_b->rt_period);
358 for_each_cpu(i, rd->span) {
359 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
360 s64 diff;
361
362 if (iter == rt_rq)
363 continue;
364
365 raw_spin_lock(&iter->rt_runtime_lock);
366 /*
367 * Either all rqs have inf runtime and there's nothing to steal
368 * or __disable_runtime() below sets a specific rq to inf to
369 * indicate its been disabled and disalow stealing.
370 */
371 if (iter->rt_runtime == RUNTIME_INF)
372 goto next;
373
374 /*
375 * From runqueues with spare time, take 1/n part of their
376 * spare time, but no more than our period.
377 */
378 diff = iter->rt_runtime - iter->rt_time;
379 if (diff > 0) {
380 diff = div_u64((u64)diff, weight);
381 if (rt_rq->rt_runtime + diff > rt_period)
382 diff = rt_period - rt_rq->rt_runtime;
383 iter->rt_runtime -= diff;
384 rt_rq->rt_runtime += diff;
385 more = 1;
386 if (rt_rq->rt_runtime == rt_period) {
387 raw_spin_unlock(&iter->rt_runtime_lock);
388 break;
389 }
390 }
391next:
392 raw_spin_unlock(&iter->rt_runtime_lock);
393 }
394 raw_spin_unlock(&rt_b->rt_runtime_lock);
395
396 return more;
397}
398
399/*
400 * Ensure this RQ takes back all the runtime it lend to its neighbours.
401 */
402static void __disable_runtime(struct rq *rq)
403{
404 struct root_domain *rd = rq->rd;
405 struct rt_rq *rt_rq;
406
407 if (unlikely(!scheduler_running))
408 return;
409
410 for_each_leaf_rt_rq(rt_rq, rq) {
411 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
412 s64 want;
413 int i;
414
415 raw_spin_lock(&rt_b->rt_runtime_lock);
416 raw_spin_lock(&rt_rq->rt_runtime_lock);
417 /*
418 * Either we're all inf and nobody needs to borrow, or we're
419 * already disabled and thus have nothing to do, or we have
420 * exactly the right amount of runtime to take out.
421 */
422 if (rt_rq->rt_runtime == RUNTIME_INF ||
423 rt_rq->rt_runtime == rt_b->rt_runtime)
424 goto balanced;
425 raw_spin_unlock(&rt_rq->rt_runtime_lock);
426
427 /*
428 * Calculate the difference between what we started out with
429 * and what we current have, that's the amount of runtime
430 * we lend and now have to reclaim.
431 */
432 want = rt_b->rt_runtime - rt_rq->rt_runtime;
433
434 /*
435 * Greedy reclaim, take back as much as we can.
436 */
437 for_each_cpu(i, rd->span) {
438 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
439 s64 diff;
440
441 /*
442 * Can't reclaim from ourselves or disabled runqueues.
443 */
444 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
445 continue;
446
447 raw_spin_lock(&iter->rt_runtime_lock);
448 if (want > 0) {
449 diff = min_t(s64, iter->rt_runtime, want);
450 iter->rt_runtime -= diff;
451 want -= diff;
452 } else {
453 iter->rt_runtime -= want;
454 want -= want;
455 }
456 raw_spin_unlock(&iter->rt_runtime_lock);
457
458 if (!want)
459 break;
460 }
461
462 raw_spin_lock(&rt_rq->rt_runtime_lock);
463 /*
464 * We cannot be left wanting - that would mean some runtime
465 * leaked out of the system.
466 */
467 BUG_ON(want);
468balanced:
469 /*
470 * Disable all the borrow logic by pretending we have inf
471 * runtime - in which case borrowing doesn't make sense.
472 */
473 rt_rq->rt_runtime = RUNTIME_INF;
474 raw_spin_unlock(&rt_rq->rt_runtime_lock);
475 raw_spin_unlock(&rt_b->rt_runtime_lock);
476 }
477}
478
479static void disable_runtime(struct rq *rq)
480{
481 unsigned long flags;
482
483 raw_spin_lock_irqsave(&rq->lock, flags);
484 __disable_runtime(rq);
485 raw_spin_unlock_irqrestore(&rq->lock, flags);
486}
487
488static void __enable_runtime(struct rq *rq)
489{
490 struct rt_rq *rt_rq;
491
492 if (unlikely(!scheduler_running))
493 return;
494
495 /*
496 * Reset each runqueue's bandwidth settings
497 */
498 for_each_leaf_rt_rq(rt_rq, rq) {
499 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
500
501 raw_spin_lock(&rt_b->rt_runtime_lock);
502 raw_spin_lock(&rt_rq->rt_runtime_lock);
503 rt_rq->rt_runtime = rt_b->rt_runtime;
504 rt_rq->rt_time = 0;
505 rt_rq->rt_throttled = 0;
506 raw_spin_unlock(&rt_rq->rt_runtime_lock);
507 raw_spin_unlock(&rt_b->rt_runtime_lock);
508 }
509}
510
511static void enable_runtime(struct rq *rq)
512{
513 unsigned long flags;
514
515 raw_spin_lock_irqsave(&rq->lock, flags);
516 __enable_runtime(rq);
517 raw_spin_unlock_irqrestore(&rq->lock, flags);
518}
519
520static int balance_runtime(struct rt_rq *rt_rq)
521{
522 int more = 0;
523
524 if (rt_rq->rt_time > rt_rq->rt_runtime) {
525 raw_spin_unlock(&rt_rq->rt_runtime_lock);
526 more = do_balance_runtime(rt_rq);
527 raw_spin_lock(&rt_rq->rt_runtime_lock);
528 }
529
530 return more;
531}
532#else /* !CONFIG_SMP */
533static inline int balance_runtime(struct rt_rq *rt_rq)
534{
535 return 0;
536}
537#endif /* CONFIG_SMP */
538
539static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
540{
541 int i, idle = 1;
542 const struct cpumask *span;
543
544 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
545 return 1;
546
547 span = sched_rt_period_mask();
548 for_each_cpu(i, span) {
549 int enqueue = 0;
550 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
551 struct rq *rq = rq_of_rt_rq(rt_rq);
552
553 raw_spin_lock(&rq->lock);
554 if (rt_rq->rt_time) {
555 u64 runtime;
556
557 raw_spin_lock(&rt_rq->rt_runtime_lock);
558 if (rt_rq->rt_throttled)
559 balance_runtime(rt_rq);
560 runtime = rt_rq->rt_runtime;
561 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
562 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
563 rt_rq->rt_throttled = 0;
564 enqueue = 1;
565 }
566 if (rt_rq->rt_time || rt_rq->rt_nr_running)
567 idle = 0;
568 raw_spin_unlock(&rt_rq->rt_runtime_lock);
569 } else if (rt_rq->rt_nr_running) {
570 idle = 0;
571 if (!rt_rq_throttled(rt_rq))
572 enqueue = 1;
573 }
574
575 if (enqueue)
576 sched_rt_rq_enqueue(rt_rq);
577 raw_spin_unlock(&rq->lock);
578 }
579
580 return idle;
581}
582
583static inline int rt_se_prio(struct sched_rt_entity *rt_se)
584{
585#ifdef CONFIG_RT_GROUP_SCHED
586 struct rt_rq *rt_rq = group_rt_rq(rt_se);
587
588 if (rt_rq)
589 return rt_rq->highest_prio.curr;
590#endif
591
592 return rt_task_of(rt_se)->prio;
593}
594
595static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
596{
597 u64 runtime = sched_rt_runtime(rt_rq);
598
599 if (rt_rq->rt_throttled)
600 return rt_rq_throttled(rt_rq);
601
602 if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
603 return 0;
604
605 balance_runtime(rt_rq);
606 runtime = sched_rt_runtime(rt_rq);
607 if (runtime == RUNTIME_INF)
608 return 0;
609
610 if (rt_rq->rt_time > runtime) {
611 rt_rq->rt_throttled = 1;
612 if (rt_rq_throttled(rt_rq)) {
613 sched_rt_rq_dequeue(rt_rq);
614 return 1;
615 }
616 }
617
618 return 0;
619}
620
621/*
622 * Update the current task's runtime statistics. Skip current tasks that
623 * are not in our scheduling class.
624 */
625static void update_curr_rt(struct rq *rq)
626{
627 struct task_struct *curr = rq->curr;
628 struct sched_rt_entity *rt_se = &curr->rt;
629 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
630 u64 delta_exec;
631
632 if (curr->sched_class != &rt_sched_class)
633 return;
634
635 delta_exec = rq->clock_task - curr->se.exec_start;
636 if (unlikely((s64)delta_exec < 0))
637 delta_exec = 0;
638
639 schedstat_set(curr->se.statistics.exec_max, max(curr->se.statistics.exec_max, delta_exec));
640
641 curr->se.sum_exec_runtime += delta_exec;
642 account_group_exec_runtime(curr, delta_exec);
643
644 curr->se.exec_start = rq->clock_task;
645 cpuacct_charge(curr, delta_exec);
646
647 sched_rt_avg_update(rq, delta_exec);
648
649 if (!rt_bandwidth_enabled())
650 return;
651
652 for_each_sched_rt_entity(rt_se) {
653 rt_rq = rt_rq_of_se(rt_se);
654
655 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
656 raw_spin_lock(&rt_rq->rt_runtime_lock);
657 rt_rq->rt_time += delta_exec;
658 if (sched_rt_runtime_exceeded(rt_rq))
659 resched_task(curr);
660 raw_spin_unlock(&rt_rq->rt_runtime_lock);
661 }
662 }
663}
664
665#if defined CONFIG_SMP
666
667static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu);
668
669static inline int next_prio(struct rq *rq)
670{
671 struct task_struct *next = pick_next_highest_task_rt(rq, rq->cpu);
672
673 if (next && rt_prio(next->prio))
674 return next->prio;
675 else
676 return MAX_RT_PRIO;
677}
678
679static void
680inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
681{
682 struct rq *rq = rq_of_rt_rq(rt_rq);
683
684 if (prio < prev_prio) {
685
686 /*
687 * If the new task is higher in priority than anything on the
688 * run-queue, we know that the previous high becomes our
689 * next-highest.
690 */
691 rt_rq->highest_prio.next = prev_prio;
692
693 if (rq->online)
694 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
695
696 } else if (prio == rt_rq->highest_prio.curr)
697 /*
698 * If the next task is equal in priority to the highest on
699 * the run-queue, then we implicitly know that the next highest
700 * task cannot be any lower than current
701 */
702 rt_rq->highest_prio.next = prio;
703 else if (prio < rt_rq->highest_prio.next)
704 /*
705 * Otherwise, we need to recompute next-highest
706 */
707 rt_rq->highest_prio.next = next_prio(rq);
708}
709
710static void
711dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
712{
713 struct rq *rq = rq_of_rt_rq(rt_rq);
714
715 if (rt_rq->rt_nr_running && (prio <= rt_rq->highest_prio.next))
716 rt_rq->highest_prio.next = next_prio(rq);
717
718 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
719 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
720}
721
722#else /* CONFIG_SMP */
723
724static inline
725void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
726static inline
727void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
728
729#endif /* CONFIG_SMP */
730
731#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
732static void
733inc_rt_prio(struct rt_rq *rt_rq, int prio)
734{
735 int prev_prio = rt_rq->highest_prio.curr;
736
737 if (prio < prev_prio)
738 rt_rq->highest_prio.curr = prio;
739
740 inc_rt_prio_smp(rt_rq, prio, prev_prio);
741}
742
743static void
744dec_rt_prio(struct rt_rq *rt_rq, int prio)
745{
746 int prev_prio = rt_rq->highest_prio.curr;
747
748 if (rt_rq->rt_nr_running) {
749
750 WARN_ON(prio < prev_prio);
751
752 /*
753 * This may have been our highest task, and therefore
754 * we may have some recomputation to do
755 */
756 if (prio == prev_prio) {
757 struct rt_prio_array *array = &rt_rq->active;
758
759 rt_rq->highest_prio.curr =
760 sched_find_first_bit(array->bitmap);
761 }
762
763 } else
764 rt_rq->highest_prio.curr = MAX_RT_PRIO;
765
766 dec_rt_prio_smp(rt_rq, prio, prev_prio);
767}
768
769#else
770
771static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
772static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
773
774#endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
775
776#ifdef CONFIG_RT_GROUP_SCHED
777
778static void
779inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
780{
781 if (rt_se_boosted(rt_se))
782 rt_rq->rt_nr_boosted++;
783
784 if (rt_rq->tg)
785 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
786}
787
788static void
789dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
790{
791 if (rt_se_boosted(rt_se))
792 rt_rq->rt_nr_boosted--;
793
794 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
795}
796
797#else /* CONFIG_RT_GROUP_SCHED */
798
799static void
800inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
801{
802 start_rt_bandwidth(&def_rt_bandwidth);
803}
804
805static inline
806void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
807
808#endif /* CONFIG_RT_GROUP_SCHED */
809
810static inline
811void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
812{
813 int prio = rt_se_prio(rt_se);
814
815 WARN_ON(!rt_prio(prio));
816 rt_rq->rt_nr_running++;
817
818 inc_rt_prio(rt_rq, prio);
819 inc_rt_migration(rt_se, rt_rq);
820 inc_rt_group(rt_se, rt_rq);
821}
822
823static inline
824void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
825{
826 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
827 WARN_ON(!rt_rq->rt_nr_running);
828 rt_rq->rt_nr_running--;
829
830 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
831 dec_rt_migration(rt_se, rt_rq);
832 dec_rt_group(rt_se, rt_rq);
833}
834
835static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
836{
837 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
838 struct rt_prio_array *array = &rt_rq->active;
839 struct rt_rq *group_rq = group_rt_rq(rt_se);
840 struct list_head *queue = array->queue + rt_se_prio(rt_se);
841
842 /*
843 * Don't enqueue the group if its throttled, or when empty.
844 * The latter is a consequence of the former when a child group
845 * get throttled and the current group doesn't have any other
846 * active members.
847 */
848 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
849 return;
850
851 if (!rt_rq->rt_nr_running)
852 list_add_leaf_rt_rq(rt_rq);
853
854 if (head)
855 list_add(&rt_se->run_list, queue);
856 else
857 list_add_tail(&rt_se->run_list, queue);
858 __set_bit(rt_se_prio(rt_se), array->bitmap);
859
860 inc_rt_tasks(rt_se, rt_rq);
861}
862
863static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
864{
865 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
866 struct rt_prio_array *array = &rt_rq->active;
867
868 list_del_init(&rt_se->run_list);
869 if (list_empty(array->queue + rt_se_prio(rt_se)))
870 __clear_bit(rt_se_prio(rt_se), array->bitmap);
871
872 dec_rt_tasks(rt_se, rt_rq);
873 if (!rt_rq->rt_nr_running)
874 list_del_leaf_rt_rq(rt_rq);
875}
876
877/*
878 * Because the prio of an upper entry depends on the lower
879 * entries, we must remove entries top - down.
880 */
881static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
882{
883 struct sched_rt_entity *back = NULL;
884
885 for_each_sched_rt_entity(rt_se) {
886 rt_se->back = back;
887 back = rt_se;
888 }
889
890 for (rt_se = back; rt_se; rt_se = rt_se->back) {
891 if (on_rt_rq(rt_se))
892 __dequeue_rt_entity(rt_se);
893 }
894}
895
896static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
897{
898 dequeue_rt_stack(rt_se);
899 for_each_sched_rt_entity(rt_se)
900 __enqueue_rt_entity(rt_se, head);
901}
902
903static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
904{
905 dequeue_rt_stack(rt_se);
906
907 for_each_sched_rt_entity(rt_se) {
908 struct rt_rq *rt_rq = group_rt_rq(rt_se);
909
910 if (rt_rq && rt_rq->rt_nr_running)
911 __enqueue_rt_entity(rt_se, false);
912 }
913}
914
915/*
916 * Adding/removing a task to/from a priority array:
917 */
918static void
919enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
920{
921 struct sched_rt_entity *rt_se = &p->rt;
922
923 if (flags & ENQUEUE_WAKEUP)
924 rt_se->timeout = 0;
925
926 enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
927
928 if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
929 enqueue_pushable_task(rq, p);
930}
931
932static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
933{
934 struct sched_rt_entity *rt_se = &p->rt;
935
936 update_curr_rt(rq);
937 dequeue_rt_entity(rt_se);
938
939 dequeue_pushable_task(rq, p);
940}
941
942/*
943 * Put task to the end of the run list without the overhead of dequeue
944 * followed by enqueue.
945 */
946static void
947requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
948{
949 if (on_rt_rq(rt_se)) {
950 struct rt_prio_array *array = &rt_rq->active;
951 struct list_head *queue = array->queue + rt_se_prio(rt_se);
952
953 if (head)
954 list_move(&rt_se->run_list, queue);
955 else
956 list_move_tail(&rt_se->run_list, queue);
957 }
958}
959
960static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
961{
962 struct sched_rt_entity *rt_se = &p->rt;
963 struct rt_rq *rt_rq;
964
965 for_each_sched_rt_entity(rt_se) {
966 rt_rq = rt_rq_of_se(rt_se);
967 requeue_rt_entity(rt_rq, rt_se, head);
968 }
969}
970
971static void yield_task_rt(struct rq *rq)
972{
973 requeue_task_rt(rq, rq->curr, 0);
974}
975
976#ifdef CONFIG_SMP
977static int find_lowest_rq(struct task_struct *task);
978
979static int
980select_task_rq_rt(struct rq *rq, struct task_struct *p, int sd_flag, int flags)
981{
982 if (sd_flag != SD_BALANCE_WAKE)
983 return smp_processor_id();
984
985 /*
986 * If the current task is an RT task, then
987 * try to see if we can wake this RT task up on another
988 * runqueue. Otherwise simply start this RT task
989 * on its current runqueue.
990 *
991 * We want to avoid overloading runqueues. If the woken
992 * task is a higher priority, then it will stay on this CPU
993 * and the lower prio task should be moved to another CPU.
994 * Even though this will probably make the lower prio task
995 * lose its cache, we do not want to bounce a higher task
996 * around just because it gave up its CPU, perhaps for a
997 * lock?
998 *
999 * For equal prio tasks, we just let the scheduler sort it out.
1000 */
1001 if (unlikely(rt_task(rq->curr)) &&
1002 (rq->curr->rt.nr_cpus_allowed < 2 ||
1003 rq->curr->prio < p->prio) &&
1004 (p->rt.nr_cpus_allowed > 1)) {
1005 int cpu = find_lowest_rq(p);
1006
1007 return (cpu == -1) ? task_cpu(p) : cpu;
1008 }
1009
1010 /*
1011 * Otherwise, just let it ride on the affined RQ and the
1012 * post-schedule router will push the preempted task away
1013 */
1014 return task_cpu(p);
1015}
1016
1017static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1018{
1019 if (rq->curr->rt.nr_cpus_allowed == 1)
1020 return;
1021
1022 if (p->rt.nr_cpus_allowed != 1
1023 && cpupri_find(&rq->rd->cpupri, p, NULL))
1024 return;
1025
1026 if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1027 return;
1028
1029 /*
1030 * There appears to be other cpus that can accept
1031 * current and none to run 'p', so lets reschedule
1032 * to try and push current away:
1033 */
1034 requeue_task_rt(rq, p, 1);
1035 resched_task(rq->curr);
1036}
1037
1038#endif /* CONFIG_SMP */
1039
1040/*
1041 * Preempt the current task with a newly woken task if needed:
1042 */
1043static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1044{
1045 if (p->prio < rq->curr->prio) {
1046 resched_task(rq->curr);
1047 return;
1048 }
1049
1050#ifdef CONFIG_SMP
1051 /*
1052 * If:
1053 *
1054 * - the newly woken task is of equal priority to the current task
1055 * - the newly woken task is non-migratable while current is migratable
1056 * - current will be preempted on the next reschedule
1057 *
1058 * we should check to see if current can readily move to a different
1059 * cpu. If so, we will reschedule to allow the push logic to try
1060 * to move current somewhere else, making room for our non-migratable
1061 * task.
1062 */
1063 if (p->prio == rq->curr->prio && !need_resched())
1064 check_preempt_equal_prio(rq, p);
1065#endif
1066}
1067
1068static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1069 struct rt_rq *rt_rq)
1070{
1071 struct rt_prio_array *array = &rt_rq->active;
1072 struct sched_rt_entity *next = NULL;
1073 struct list_head *queue;
1074 int idx;
1075
1076 idx = sched_find_first_bit(array->bitmap);
1077 BUG_ON(idx >= MAX_RT_PRIO);
1078
1079 queue = array->queue + idx;
1080 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1081
1082 return next;
1083}
1084
1085static struct task_struct *_pick_next_task_rt(struct rq *rq)
1086{
1087 struct sched_rt_entity *rt_se;
1088 struct task_struct *p;
1089 struct rt_rq *rt_rq;
1090
1091 rt_rq = &rq->rt;
1092
1093 if (unlikely(!rt_rq->rt_nr_running))
1094 return NULL;
1095
1096 if (rt_rq_throttled(rt_rq))
1097 return NULL;
1098
1099 do {
1100 rt_se = pick_next_rt_entity(rq, rt_rq);
1101 BUG_ON(!rt_se);
1102 rt_rq = group_rt_rq(rt_se);
1103 } while (rt_rq);
1104
1105 p = rt_task_of(rt_se);
1106 p->se.exec_start = rq->clock_task;
1107
1108 return p;
1109}
1110
1111static struct task_struct *pick_next_task_rt(struct rq *rq)
1112{
1113 struct task_struct *p = _pick_next_task_rt(rq);
1114
1115 /* The running task is never eligible for pushing */
1116 if (p)
1117 dequeue_pushable_task(rq, p);
1118
1119#ifdef CONFIG_SMP
1120 /*
1121 * We detect this state here so that we can avoid taking the RQ
1122 * lock again later if there is no need to push
1123 */
1124 rq->post_schedule = has_pushable_tasks(rq);
1125#endif
1126
1127 return p;
1128}
1129
1130static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1131{
1132 update_curr_rt(rq);
1133 p->se.exec_start = 0;
1134
1135 /*
1136 * The previous task needs to be made eligible for pushing
1137 * if it is still active
1138 */
1139 if (p->se.on_rq && p->rt.nr_cpus_allowed > 1)
1140 enqueue_pushable_task(rq, p);
1141}
1142
1143#ifdef CONFIG_SMP
1144
1145/* Only try algorithms three times */
1146#define RT_MAX_TRIES 3
1147
1148static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
1149
1150static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1151{
1152 if (!task_running(rq, p) &&
1153 (cpu < 0 || cpumask_test_cpu(cpu, &p->cpus_allowed)) &&
1154 (p->rt.nr_cpus_allowed > 1))
1155 return 1;
1156 return 0;
1157}
1158
1159/* Return the second highest RT task, NULL otherwise */
1160static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
1161{
1162 struct task_struct *next = NULL;
1163 struct sched_rt_entity *rt_se;
1164 struct rt_prio_array *array;
1165 struct rt_rq *rt_rq;
1166 int idx;
1167
1168 for_each_leaf_rt_rq(rt_rq, rq) {
1169 array = &rt_rq->active;
1170 idx = sched_find_first_bit(array->bitmap);
1171next_idx:
1172 if (idx >= MAX_RT_PRIO)
1173 continue;
1174 if (next && next->prio < idx)
1175 continue;
1176 list_for_each_entry(rt_se, array->queue + idx, run_list) {
1177 struct task_struct *p;
1178
1179 if (!rt_entity_is_task(rt_se))
1180 continue;
1181
1182 p = rt_task_of(rt_se);
1183 if (pick_rt_task(rq, p, cpu)) {
1184 next = p;
1185 break;
1186 }
1187 }
1188 if (!next) {
1189 idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
1190 goto next_idx;
1191 }
1192 }
1193
1194 return next;
1195}
1196
1197static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1198
1199static int find_lowest_rq(struct task_struct *task)
1200{
1201 struct sched_domain *sd;
1202 struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
1203 int this_cpu = smp_processor_id();
1204 int cpu = task_cpu(task);
1205
1206 if (task->rt.nr_cpus_allowed == 1)
1207 return -1; /* No other targets possible */
1208
1209 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1210 return -1; /* No targets found */
1211
1212 /*
1213 * At this point we have built a mask of cpus representing the
1214 * lowest priority tasks in the system. Now we want to elect
1215 * the best one based on our affinity and topology.
1216 *
1217 * We prioritize the last cpu that the task executed on since
1218 * it is most likely cache-hot in that location.
1219 */
1220 if (cpumask_test_cpu(cpu, lowest_mask))
1221 return cpu;
1222
1223 /*
1224 * Otherwise, we consult the sched_domains span maps to figure
1225 * out which cpu is logically closest to our hot cache data.
1226 */
1227 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1228 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1229
1230 for_each_domain(cpu, sd) {
1231 if (sd->flags & SD_WAKE_AFFINE) {
1232 int best_cpu;
1233
1234 /*
1235 * "this_cpu" is cheaper to preempt than a
1236 * remote processor.
1237 */
1238 if (this_cpu != -1 &&
1239 cpumask_test_cpu(this_cpu, sched_domain_span(sd)))
1240 return this_cpu;
1241
1242 best_cpu = cpumask_first_and(lowest_mask,
1243 sched_domain_span(sd));
1244 if (best_cpu < nr_cpu_ids)
1245 return best_cpu;
1246 }
1247 }
1248
1249 /*
1250 * And finally, if there were no matches within the domains
1251 * just give the caller *something* to work with from the compatible
1252 * locations.
1253 */
1254 if (this_cpu != -1)
1255 return this_cpu;
1256
1257 cpu = cpumask_any(lowest_mask);
1258 if (cpu < nr_cpu_ids)
1259 return cpu;
1260 return -1;
1261}
1262
1263/* Will lock the rq it finds */
1264static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1265{
1266 struct rq *lowest_rq = NULL;
1267 int tries;
1268 int cpu;
1269
1270 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1271 cpu = find_lowest_rq(task);
1272
1273 if ((cpu == -1) || (cpu == rq->cpu))
1274 break;
1275
1276 lowest_rq = cpu_rq(cpu);
1277
1278 /* if the prio of this runqueue changed, try again */
1279 if (double_lock_balance(rq, lowest_rq)) {
1280 /*
1281 * We had to unlock the run queue. In
1282 * the mean time, task could have
1283 * migrated already or had its affinity changed.
1284 * Also make sure that it wasn't scheduled on its rq.
1285 */
1286 if (unlikely(task_rq(task) != rq ||
1287 !cpumask_test_cpu(lowest_rq->cpu,
1288 &task->cpus_allowed) ||
1289 task_running(rq, task) ||
1290 !task->se.on_rq)) {
1291
1292 raw_spin_unlock(&lowest_rq->lock);
1293 lowest_rq = NULL;
1294 break;
1295 }
1296 }
1297
1298 /* If this rq is still suitable use it. */
1299 if (lowest_rq->rt.highest_prio.curr > task->prio)
1300 break;
1301
1302 /* try again */
1303 double_unlock_balance(rq, lowest_rq);
1304 lowest_rq = NULL;
1305 }
1306
1307 return lowest_rq;
1308}
1309
1310static struct task_struct *pick_next_pushable_task(struct rq *rq)
1311{
1312 struct task_struct *p;
1313
1314 if (!has_pushable_tasks(rq))
1315 return NULL;
1316
1317 p = plist_first_entry(&rq->rt.pushable_tasks,
1318 struct task_struct, pushable_tasks);
1319
1320 BUG_ON(rq->cpu != task_cpu(p));
1321 BUG_ON(task_current(rq, p));
1322 BUG_ON(p->rt.nr_cpus_allowed <= 1);
1323
1324 BUG_ON(!p->se.on_rq);
1325 BUG_ON(!rt_task(p));
1326
1327 return p;
1328}
1329
1330/*
1331 * If the current CPU has more than one RT task, see if the non
1332 * running task can migrate over to a CPU that is running a task
1333 * of lesser priority.
1334 */
1335static int push_rt_task(struct rq *rq)
1336{
1337 struct task_struct *next_task;
1338 struct rq *lowest_rq;
1339
1340 if (!rq->rt.overloaded)
1341 return 0;
1342
1343 next_task = pick_next_pushable_task(rq);
1344 if (!next_task)
1345 return 0;
1346
1347retry:
1348 if (unlikely(next_task == rq->curr)) {
1349 WARN_ON(1);
1350 return 0;
1351 }
1352
1353 /*
1354 * It's possible that the next_task slipped in of
1355 * higher priority than current. If that's the case
1356 * just reschedule current.
1357 */
1358 if (unlikely(next_task->prio < rq->curr->prio)) {
1359 resched_task(rq->curr);
1360 return 0;
1361 }
1362
1363 /* We might release rq lock */
1364 get_task_struct(next_task);
1365
1366 /* find_lock_lowest_rq locks the rq if found */
1367 lowest_rq = find_lock_lowest_rq(next_task, rq);
1368 if (!lowest_rq) {
1369 struct task_struct *task;
1370 /*
1371 * find lock_lowest_rq releases rq->lock
1372 * so it is possible that next_task has migrated.
1373 *
1374 * We need to make sure that the task is still on the same
1375 * run-queue and is also still the next task eligible for
1376 * pushing.
1377 */
1378 task = pick_next_pushable_task(rq);
1379 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1380 /*
1381 * If we get here, the task hasnt moved at all, but
1382 * it has failed to push. We will not try again,
1383 * since the other cpus will pull from us when they
1384 * are ready.
1385 */
1386 dequeue_pushable_task(rq, next_task);
1387 goto out;
1388 }
1389
1390 if (!task)
1391 /* No more tasks, just exit */
1392 goto out;
1393
1394 /*
1395 * Something has shifted, try again.
1396 */
1397 put_task_struct(next_task);
1398 next_task = task;
1399 goto retry;
1400 }
1401
1402 deactivate_task(rq, next_task, 0);
1403 set_task_cpu(next_task, lowest_rq->cpu);
1404 activate_task(lowest_rq, next_task, 0);
1405
1406 resched_task(lowest_rq->curr);
1407
1408 double_unlock_balance(rq, lowest_rq);
1409
1410out:
1411 put_task_struct(next_task);
1412
1413 return 1;
1414}
1415
1416static void push_rt_tasks(struct rq *rq)
1417{
1418 /* push_rt_task will return true if it moved an RT */
1419 while (push_rt_task(rq))
1420 ;
1421}
1422
1423static int pull_rt_task(struct rq *this_rq)
1424{
1425 int this_cpu = this_rq->cpu, ret = 0, cpu;
1426 struct task_struct *p;
1427 struct rq *src_rq;
1428
1429 if (likely(!rt_overloaded(this_rq)))
1430 return 0;
1431
1432 for_each_cpu(cpu, this_rq->rd->rto_mask) {
1433 if (this_cpu == cpu)
1434 continue;
1435
1436 src_rq = cpu_rq(cpu);
1437
1438 /*
1439 * Don't bother taking the src_rq->lock if the next highest
1440 * task is known to be lower-priority than our current task.
1441 * This may look racy, but if this value is about to go
1442 * logically higher, the src_rq will push this task away.
1443 * And if its going logically lower, we do not care
1444 */
1445 if (src_rq->rt.highest_prio.next >=
1446 this_rq->rt.highest_prio.curr)
1447 continue;
1448
1449 /*
1450 * We can potentially drop this_rq's lock in
1451 * double_lock_balance, and another CPU could
1452 * alter this_rq
1453 */
1454 double_lock_balance(this_rq, src_rq);
1455
1456 /*
1457 * Are there still pullable RT tasks?
1458 */
1459 if (src_rq->rt.rt_nr_running <= 1)
1460 goto skip;
1461
1462 p = pick_next_highest_task_rt(src_rq, this_cpu);
1463
1464 /*
1465 * Do we have an RT task that preempts
1466 * the to-be-scheduled task?
1467 */
1468 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
1469 WARN_ON(p == src_rq->curr);
1470 WARN_ON(!p->se.on_rq);
1471
1472 /*
1473 * There's a chance that p is higher in priority
1474 * than what's currently running on its cpu.
1475 * This is just that p is wakeing up and hasn't
1476 * had a chance to schedule. We only pull
1477 * p if it is lower in priority than the
1478 * current task on the run queue
1479 */
1480 if (p->prio < src_rq->curr->prio)
1481 goto skip;
1482
1483 ret = 1;
1484
1485 deactivate_task(src_rq, p, 0);
1486 set_task_cpu(p, this_cpu);
1487 activate_task(this_rq, p, 0);
1488 /*
1489 * We continue with the search, just in
1490 * case there's an even higher prio task
1491 * in another runqueue. (low likelyhood
1492 * but possible)
1493 */
1494 }
1495skip:
1496 double_unlock_balance(this_rq, src_rq);
1497 }
1498
1499 return ret;
1500}
1501
1502static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1503{
1504 /* Try to pull RT tasks here if we lower this rq's prio */
1505 if (unlikely(rt_task(prev)) && rq->rt.highest_prio.curr > prev->prio)
1506 pull_rt_task(rq);
1507}
1508
1509static void post_schedule_rt(struct rq *rq)
1510{
1511 push_rt_tasks(rq);
1512}
1513
1514/*
1515 * If we are not running and we are not going to reschedule soon, we should
1516 * try to push tasks away now
1517 */
1518static void task_woken_rt(struct rq *rq, struct task_struct *p)
1519{
1520 if (!task_running(rq, p) &&
1521 !test_tsk_need_resched(rq->curr) &&
1522 has_pushable_tasks(rq) &&
1523 p->rt.nr_cpus_allowed > 1 &&
1524 rt_task(rq->curr) &&
1525 (rq->curr->rt.nr_cpus_allowed < 2 ||
1526 rq->curr->prio < p->prio))
1527 push_rt_tasks(rq);
1528}
1529
1530static void set_cpus_allowed_rt(struct task_struct *p,
1531 const struct cpumask *new_mask)
1532{
1533 int weight = cpumask_weight(new_mask);
1534
1535 BUG_ON(!rt_task(p));
1536
1537 /*
1538 * Update the migration status of the RQ if we have an RT task
1539 * which is running AND changing its weight value.
1540 */
1541 if (p->se.on_rq && (weight != p->rt.nr_cpus_allowed)) {
1542 struct rq *rq = task_rq(p);
1543
1544 if (!task_current(rq, p)) {
1545 /*
1546 * Make sure we dequeue this task from the pushable list
1547 * before going further. It will either remain off of
1548 * the list because we are no longer pushable, or it
1549 * will be requeued.
1550 */
1551 if (p->rt.nr_cpus_allowed > 1)
1552 dequeue_pushable_task(rq, p);
1553
1554 /*
1555 * Requeue if our weight is changing and still > 1
1556 */
1557 if (weight > 1)
1558 enqueue_pushable_task(rq, p);
1559
1560 }
1561
1562 if ((p->rt.nr_cpus_allowed <= 1) && (weight > 1)) {
1563 rq->rt.rt_nr_migratory++;
1564 } else if ((p->rt.nr_cpus_allowed > 1) && (weight <= 1)) {
1565 BUG_ON(!rq->rt.rt_nr_migratory);
1566 rq->rt.rt_nr_migratory--;
1567 }
1568
1569 update_rt_migration(&rq->rt);
1570 }
1571
1572 cpumask_copy(&p->cpus_allowed, new_mask);
1573 p->rt.nr_cpus_allowed = weight;
1574}
1575
1576/* Assumes rq->lock is held */
1577static void rq_online_rt(struct rq *rq)
1578{
1579 if (rq->rt.overloaded)
1580 rt_set_overload(rq);
1581
1582 __enable_runtime(rq);
1583
1584 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1585}
1586
1587/* Assumes rq->lock is held */
1588static void rq_offline_rt(struct rq *rq)
1589{
1590 if (rq->rt.overloaded)
1591 rt_clear_overload(rq);
1592
1593 __disable_runtime(rq);
1594
1595 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1596}
1597
1598/*
1599 * When switch from the rt queue, we bring ourselves to a position
1600 * that we might want to pull RT tasks from other runqueues.
1601 */
1602static void switched_from_rt(struct rq *rq, struct task_struct *p)
1603{
1604 /*
1605 * If there are other RT tasks then we will reschedule
1606 * and the scheduling of the other RT tasks will handle
1607 * the balancing. But if we are the last RT task
1608 * we may need to handle the pulling of RT tasks
1609 * now.
1610 */
1611 if (p->se.on_rq && !rq->rt.rt_nr_running)
1612 pull_rt_task(rq);
1613}
1614
1615static inline void init_sched_rt_class(void)
1616{
1617 unsigned int i;
1618
1619 for_each_possible_cpu(i)
1620 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
1621 GFP_KERNEL, cpu_to_node(i));
1622}
1623#endif /* CONFIG_SMP */
1624
1625/*
1626 * When switching a task to RT, we may overload the runqueue
1627 * with RT tasks. In this case we try to push them off to
1628 * other runqueues.
1629 */
1630static void switched_to_rt(struct rq *rq, struct task_struct *p)
1631{
1632 int check_resched = 1;
1633
1634 /*
1635 * If we are already running, then there's nothing
1636 * that needs to be done. But if we are not running
1637 * we may need to preempt the current running task.
1638 * If that current running task is also an RT task
1639 * then see if we can move to another run queue.
1640 */
1641 if (p->se.on_rq && rq->curr != p) {
1642#ifdef CONFIG_SMP
1643 if (rq->rt.overloaded && push_rt_task(rq) &&
1644 /* Don't resched if we changed runqueues */
1645 rq != task_rq(p))
1646 check_resched = 0;
1647#endif /* CONFIG_SMP */
1648 if (check_resched && p->prio < rq->curr->prio)
1649 resched_task(rq->curr);
1650 }
1651}
1652
1653/*
1654 * Priority of the task has changed. This may cause
1655 * us to initiate a push or pull.
1656 */
1657static void
1658prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
1659{
1660 if (!p->se.on_rq)
1661 return;
1662
1663 if (rq->curr == p) {
1664#ifdef CONFIG_SMP
1665 /*
1666 * If our priority decreases while running, we
1667 * may need to pull tasks to this runqueue.
1668 */
1669 if (oldprio < p->prio)
1670 pull_rt_task(rq);
1671 /*
1672 * If there's a higher priority task waiting to run
1673 * then reschedule. Note, the above pull_rt_task
1674 * can release the rq lock and p could migrate.
1675 * Only reschedule if p is still on the same runqueue.
1676 */
1677 if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
1678 resched_task(p);
1679#else
1680 /* For UP simply resched on drop of prio */
1681 if (oldprio < p->prio)
1682 resched_task(p);
1683#endif /* CONFIG_SMP */
1684 } else {
1685 /*
1686 * This task is not running, but if it is
1687 * greater than the current running task
1688 * then reschedule.
1689 */
1690 if (p->prio < rq->curr->prio)
1691 resched_task(rq->curr);
1692 }
1693}
1694
1695static void watchdog(struct rq *rq, struct task_struct *p)
1696{
1697 unsigned long soft, hard;
1698
1699 /* max may change after cur was read, this will be fixed next tick */
1700 soft = task_rlimit(p, RLIMIT_RTTIME);
1701 hard = task_rlimit_max(p, RLIMIT_RTTIME);
1702
1703 if (soft != RLIM_INFINITY) {
1704 unsigned long next;
1705
1706 p->rt.timeout++;
1707 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1708 if (p->rt.timeout > next)
1709 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
1710 }
1711}
1712
1713static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1714{
1715 update_curr_rt(rq);
1716
1717 watchdog(rq, p);
1718
1719 /*
1720 * RR tasks need a special form of timeslice management.
1721 * FIFO tasks have no timeslices.
1722 */
1723 if (p->policy != SCHED_RR)
1724 return;
1725
1726 if (--p->rt.time_slice)
1727 return;
1728
1729 p->rt.time_slice = DEF_TIMESLICE;
1730
1731 /*
1732 * Requeue to the end of queue if we are not the only element
1733 * on the queue:
1734 */
1735 if (p->rt.run_list.prev != p->rt.run_list.next) {
1736 requeue_task_rt(rq, p, 0);
1737 set_tsk_need_resched(p);
1738 }
1739}
1740
1741static void set_curr_task_rt(struct rq *rq)
1742{
1743 struct task_struct *p = rq->curr;
1744
1745 p->se.exec_start = rq->clock_task;
1746
1747 /* The running task is never eligible for pushing */
1748 dequeue_pushable_task(rq, p);
1749}
1750
1751static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
1752{
1753 /*
1754 * Time slice is 0 for SCHED_FIFO tasks
1755 */
1756 if (task->policy == SCHED_RR)
1757 return DEF_TIMESLICE;
1758 else
1759 return 0;
1760}
1761
1762static const struct sched_class rt_sched_class = {
1763 .next = &fair_sched_class,
1764 .enqueue_task = enqueue_task_rt,
1765 .dequeue_task = dequeue_task_rt,
1766 .yield_task = yield_task_rt,
1767
1768 .check_preempt_curr = check_preempt_curr_rt,
1769
1770 .pick_next_task = pick_next_task_rt,
1771 .put_prev_task = put_prev_task_rt,
1772
1773#ifdef CONFIG_SMP
1774 .select_task_rq = select_task_rq_rt,
1775
1776 .set_cpus_allowed = set_cpus_allowed_rt,
1777 .rq_online = rq_online_rt,
1778 .rq_offline = rq_offline_rt,
1779 .pre_schedule = pre_schedule_rt,
1780 .post_schedule = post_schedule_rt,
1781 .task_woken = task_woken_rt,
1782 .switched_from = switched_from_rt,
1783#endif
1784
1785 .set_curr_task = set_curr_task_rt,
1786 .task_tick = task_tick_rt,
1787
1788 .get_rr_interval = get_rr_interval_rt,
1789
1790 .prio_changed = prio_changed_rt,
1791 .switched_to = switched_to_rt,
1792};
1793
1794#ifdef CONFIG_SCHED_DEBUG
1795extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
1796
1797static void print_rt_stats(struct seq_file *m, int cpu)
1798{
1799 struct rt_rq *rt_rq;
1800
1801 rcu_read_lock();
1802 for_each_leaf_rt_rq(rt_rq, cpu_rq(cpu))
1803 print_rt_rq(m, cpu, rt_rq);
1804 rcu_read_unlock();
1805}
1806#endif /* CONFIG_SCHED_DEBUG */
1807