sched: rt: move some code around
[linux-2.6.git] / kernel / sched_rt.c
1 /*
2  * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
3  * policies)
4  */
5
6 #ifdef CONFIG_SMP
7
8 static inline int rt_overloaded(struct rq *rq)
9 {
10         return atomic_read(&rq->rd->rto_count);
11 }
12
13 static inline void rt_set_overload(struct rq *rq)
14 {
15         if (!rq->online)
16                 return;
17
18         cpu_set(rq->cpu, rq->rd->rto_mask);
19         /*
20          * Make sure the mask is visible before we set
21          * the overload count. That is checked to determine
22          * if we should look at the mask. It would be a shame
23          * if we looked at the mask, but the mask was not
24          * updated yet.
25          */
26         wmb();
27         atomic_inc(&rq->rd->rto_count);
28 }
29
30 static inline void rt_clear_overload(struct rq *rq)
31 {
32         if (!rq->online)
33                 return;
34
35         /* the order here really doesn't matter */
36         atomic_dec(&rq->rd->rto_count);
37         cpu_clear(rq->cpu, rq->rd->rto_mask);
38 }
39
40 static void update_rt_migration(struct rq *rq)
41 {
42         if (rq->rt.rt_nr_migratory && (rq->rt.rt_nr_running > 1)) {
43                 if (!rq->rt.overloaded) {
44                         rt_set_overload(rq);
45                         rq->rt.overloaded = 1;
46                 }
47         } else if (rq->rt.overloaded) {
48                 rt_clear_overload(rq);
49                 rq->rt.overloaded = 0;
50         }
51 }
52 #endif /* CONFIG_SMP */
53
54 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
55 {
56         return container_of(rt_se, struct task_struct, rt);
57 }
58
59 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
60 {
61         return !list_empty(&rt_se->run_list);
62 }
63
64 #ifdef CONFIG_RT_GROUP_SCHED
65
66 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
67 {
68         if (!rt_rq->tg)
69                 return RUNTIME_INF;
70
71         return rt_rq->rt_runtime;
72 }
73
74 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
75 {
76         return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
77 }
78
79 #define for_each_leaf_rt_rq(rt_rq, rq) \
80         list_for_each_entry(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
81
82 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
83 {
84         return rt_rq->rq;
85 }
86
87 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
88 {
89         return rt_se->rt_rq;
90 }
91
92 #define for_each_sched_rt_entity(rt_se) \
93         for (; rt_se; rt_se = rt_se->parent)
94
95 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
96 {
97         return rt_se->my_q;
98 }
99
100 static void enqueue_rt_entity(struct sched_rt_entity *rt_se);
101 static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
102
103 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
104 {
105         struct sched_rt_entity *rt_se = rt_rq->rt_se;
106
107         if (rt_se && !on_rt_rq(rt_se) && rt_rq->rt_nr_running) {
108                 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
109
110                 enqueue_rt_entity(rt_se);
111                 if (rt_rq->highest_prio < curr->prio)
112                         resched_task(curr);
113         }
114 }
115
116 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
117 {
118         struct sched_rt_entity *rt_se = rt_rq->rt_se;
119
120         if (rt_se && on_rt_rq(rt_se))
121                 dequeue_rt_entity(rt_se);
122 }
123
124 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
125 {
126         return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
127 }
128
129 static int rt_se_boosted(struct sched_rt_entity *rt_se)
130 {
131         struct rt_rq *rt_rq = group_rt_rq(rt_se);
132         struct task_struct *p;
133
134         if (rt_rq)
135                 return !!rt_rq->rt_nr_boosted;
136
137         p = rt_task_of(rt_se);
138         return p->prio != p->normal_prio;
139 }
140
141 #ifdef CONFIG_SMP
142 static inline cpumask_t sched_rt_period_mask(void)
143 {
144         return cpu_rq(smp_processor_id())->rd->span;
145 }
146 #else
147 static inline cpumask_t sched_rt_period_mask(void)
148 {
149         return cpu_online_map;
150 }
151 #endif
152
153 static inline
154 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
155 {
156         return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
157 }
158
159 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
160 {
161         return &rt_rq->tg->rt_bandwidth;
162 }
163
164 #else
165
166 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
167 {
168         return rt_rq->rt_runtime;
169 }
170
171 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
172 {
173         return ktime_to_ns(def_rt_bandwidth.rt_period);
174 }
175
176 #define for_each_leaf_rt_rq(rt_rq, rq) \
177         for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
178
179 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
180 {
181         return container_of(rt_rq, struct rq, rt);
182 }
183
184 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
185 {
186         struct task_struct *p = rt_task_of(rt_se);
187         struct rq *rq = task_rq(p);
188
189         return &rq->rt;
190 }
191
192 #define for_each_sched_rt_entity(rt_se) \
193         for (; rt_se; rt_se = NULL)
194
195 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
196 {
197         return NULL;
198 }
199
200 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
201 {
202 }
203
204 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
205 {
206 }
207
208 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
209 {
210         return rt_rq->rt_throttled;
211 }
212
213 static inline cpumask_t sched_rt_period_mask(void)
214 {
215         return cpu_online_map;
216 }
217
218 static inline
219 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
220 {
221         return &cpu_rq(cpu)->rt;
222 }
223
224 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
225 {
226         return &def_rt_bandwidth;
227 }
228
229 #endif
230
231 #ifdef CONFIG_SMP
232 static int do_balance_runtime(struct rt_rq *rt_rq)
233 {
234         struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
235         struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
236         int i, weight, more = 0;
237         u64 rt_period;
238
239         weight = cpus_weight(rd->span);
240
241         spin_lock(&rt_b->rt_runtime_lock);
242         rt_period = ktime_to_ns(rt_b->rt_period);
243         for_each_cpu_mask(i, rd->span) {
244                 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
245                 s64 diff;
246
247                 if (iter == rt_rq)
248                         continue;
249
250                 spin_lock(&iter->rt_runtime_lock);
251                 if (iter->rt_runtime == RUNTIME_INF)
252                         goto next;
253
254                 diff = iter->rt_runtime - iter->rt_time;
255                 if (diff > 0) {
256                         do_div(diff, weight);
257                         if (rt_rq->rt_runtime + diff > rt_period)
258                                 diff = rt_period - rt_rq->rt_runtime;
259                         iter->rt_runtime -= diff;
260                         rt_rq->rt_runtime += diff;
261                         more = 1;
262                         if (rt_rq->rt_runtime == rt_period) {
263                                 spin_unlock(&iter->rt_runtime_lock);
264                                 break;
265                         }
266                 }
267 next:
268                 spin_unlock(&iter->rt_runtime_lock);
269         }
270         spin_unlock(&rt_b->rt_runtime_lock);
271
272         return more;
273 }
274
275 static void __disable_runtime(struct rq *rq)
276 {
277         struct root_domain *rd = rq->rd;
278         struct rt_rq *rt_rq;
279
280         if (unlikely(!scheduler_running))
281                 return;
282
283         for_each_leaf_rt_rq(rt_rq, rq) {
284                 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
285                 s64 want;
286                 int i;
287
288                 spin_lock(&rt_b->rt_runtime_lock);
289                 spin_lock(&rt_rq->rt_runtime_lock);
290                 if (rt_rq->rt_runtime == RUNTIME_INF ||
291                                 rt_rq->rt_runtime == rt_b->rt_runtime)
292                         goto balanced;
293                 spin_unlock(&rt_rq->rt_runtime_lock);
294
295                 want = rt_b->rt_runtime - rt_rq->rt_runtime;
296
297                 for_each_cpu_mask(i, rd->span) {
298                         struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
299                         s64 diff;
300
301                         if (iter == rt_rq)
302                                 continue;
303
304                         spin_lock(&iter->rt_runtime_lock);
305                         if (want > 0) {
306                                 diff = min_t(s64, iter->rt_runtime, want);
307                                 iter->rt_runtime -= diff;
308                                 want -= diff;
309                         } else {
310                                 iter->rt_runtime -= want;
311                                 want -= want;
312                         }
313                         spin_unlock(&iter->rt_runtime_lock);
314
315                         if (!want)
316                                 break;
317                 }
318
319                 spin_lock(&rt_rq->rt_runtime_lock);
320                 BUG_ON(want);
321 balanced:
322                 rt_rq->rt_runtime = RUNTIME_INF;
323                 spin_unlock(&rt_rq->rt_runtime_lock);
324                 spin_unlock(&rt_b->rt_runtime_lock);
325         }
326 }
327
328 static void disable_runtime(struct rq *rq)
329 {
330         unsigned long flags;
331
332         spin_lock_irqsave(&rq->lock, flags);
333         __disable_runtime(rq);
334         spin_unlock_irqrestore(&rq->lock, flags);
335 }
336
337 static void __enable_runtime(struct rq *rq)
338 {
339         struct root_domain *rd = rq->rd;
340         struct rt_rq *rt_rq;
341
342         if (unlikely(!scheduler_running))
343                 return;
344
345         for_each_leaf_rt_rq(rt_rq, rq) {
346                 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
347
348                 spin_lock(&rt_b->rt_runtime_lock);
349                 spin_lock(&rt_rq->rt_runtime_lock);
350                 rt_rq->rt_runtime = rt_b->rt_runtime;
351                 rt_rq->rt_time = 0;
352                 spin_unlock(&rt_rq->rt_runtime_lock);
353                 spin_unlock(&rt_b->rt_runtime_lock);
354         }
355 }
356
357 static void enable_runtime(struct rq *rq)
358 {
359         unsigned long flags;
360
361         spin_lock_irqsave(&rq->lock, flags);
362         __enable_runtime(rq);
363         spin_unlock_irqrestore(&rq->lock, flags);
364 }
365
366 static int balance_runtime(struct rt_rq *rt_rq)
367 {
368         int more = 0;
369
370         if (rt_rq->rt_time > rt_rq->rt_runtime) {
371                 spin_unlock(&rt_rq->rt_runtime_lock);
372                 more = do_balance_runtime(rt_rq);
373                 spin_lock(&rt_rq->rt_runtime_lock);
374         }
375
376         return more;
377 }
378 #else
379 static inline int balance_runtime(struct rt_rq *rt_rq)
380 {
381         return 0;
382 }
383 #endif
384
385 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
386 {
387         int i, idle = 1;
388         cpumask_t span;
389
390         if (rt_b->rt_runtime == RUNTIME_INF)
391                 return 1;
392
393         span = sched_rt_period_mask();
394         for_each_cpu_mask(i, span) {
395                 int enqueue = 0;
396                 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
397                 struct rq *rq = rq_of_rt_rq(rt_rq);
398
399                 spin_lock(&rq->lock);
400                 if (rt_rq->rt_time) {
401                         u64 runtime;
402
403                         spin_lock(&rt_rq->rt_runtime_lock);
404                         if (rt_rq->rt_throttled)
405                                 balance_runtime(rt_rq);
406                         runtime = rt_rq->rt_runtime;
407                         rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
408                         if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
409                                 rt_rq->rt_throttled = 0;
410                                 enqueue = 1;
411                         }
412                         if (rt_rq->rt_time || rt_rq->rt_nr_running)
413                                 idle = 0;
414                         spin_unlock(&rt_rq->rt_runtime_lock);
415                 }
416
417                 if (enqueue)
418                         sched_rt_rq_enqueue(rt_rq);
419                 spin_unlock(&rq->lock);
420         }
421
422         return idle;
423 }
424
425 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
426 {
427 #ifdef CONFIG_RT_GROUP_SCHED
428         struct rt_rq *rt_rq = group_rt_rq(rt_se);
429
430         if (rt_rq)
431                 return rt_rq->highest_prio;
432 #endif
433
434         return rt_task_of(rt_se)->prio;
435 }
436
437 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
438 {
439         u64 runtime = sched_rt_runtime(rt_rq);
440
441         if (runtime == RUNTIME_INF)
442                 return 0;
443
444         if (rt_rq->rt_throttled)
445                 return rt_rq_throttled(rt_rq);
446
447         if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
448                 return 0;
449
450         balance_runtime(rt_rq);
451         runtime = sched_rt_runtime(rt_rq);
452         if (runtime == RUNTIME_INF)
453                 return 0;
454
455         if (rt_rq->rt_time > runtime) {
456                 rt_rq->rt_throttled = 1;
457                 if (rt_rq_throttled(rt_rq)) {
458                         sched_rt_rq_dequeue(rt_rq);
459                         return 1;
460                 }
461         }
462
463         return 0;
464 }
465
466 /*
467  * Update the current task's runtime statistics. Skip current tasks that
468  * are not in our scheduling class.
469  */
470 static void update_curr_rt(struct rq *rq)
471 {
472         struct task_struct *curr = rq->curr;
473         struct sched_rt_entity *rt_se = &curr->rt;
474         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
475         u64 delta_exec;
476
477         if (!task_has_rt_policy(curr))
478                 return;
479
480         delta_exec = rq->clock - curr->se.exec_start;
481         if (unlikely((s64)delta_exec < 0))
482                 delta_exec = 0;
483
484         schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec));
485
486         curr->se.sum_exec_runtime += delta_exec;
487         curr->se.exec_start = rq->clock;
488         cpuacct_charge(curr, delta_exec);
489
490         for_each_sched_rt_entity(rt_se) {
491                 rt_rq = rt_rq_of_se(rt_se);
492
493                 spin_lock(&rt_rq->rt_runtime_lock);
494                 rt_rq->rt_time += delta_exec;
495                 if (sched_rt_runtime_exceeded(rt_rq))
496                         resched_task(curr);
497                 spin_unlock(&rt_rq->rt_runtime_lock);
498         }
499 }
500
501 static inline
502 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
503 {
504         WARN_ON(!rt_prio(rt_se_prio(rt_se)));
505         rt_rq->rt_nr_running++;
506 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
507         if (rt_se_prio(rt_se) < rt_rq->highest_prio) {
508                 struct rq *rq = rq_of_rt_rq(rt_rq);
509
510                 rt_rq->highest_prio = rt_se_prio(rt_se);
511 #ifdef CONFIG_SMP
512                 if (rq->online)
513                         cpupri_set(&rq->rd->cpupri, rq->cpu,
514                                    rt_se_prio(rt_se));
515 #endif
516         }
517 #endif
518 #ifdef CONFIG_SMP
519         if (rt_se->nr_cpus_allowed > 1) {
520                 struct rq *rq = rq_of_rt_rq(rt_rq);
521
522                 rq->rt.rt_nr_migratory++;
523         }
524
525         update_rt_migration(rq_of_rt_rq(rt_rq));
526 #endif
527 #ifdef CONFIG_RT_GROUP_SCHED
528         if (rt_se_boosted(rt_se))
529                 rt_rq->rt_nr_boosted++;
530
531         if (rt_rq->tg)
532                 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
533 #else
534         start_rt_bandwidth(&def_rt_bandwidth);
535 #endif
536 }
537
538 static inline
539 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
540 {
541 #ifdef CONFIG_SMP
542         int highest_prio = rt_rq->highest_prio;
543 #endif
544
545         WARN_ON(!rt_prio(rt_se_prio(rt_se)));
546         WARN_ON(!rt_rq->rt_nr_running);
547         rt_rq->rt_nr_running--;
548 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
549         if (rt_rq->rt_nr_running) {
550                 struct rt_prio_array *array;
551
552                 WARN_ON(rt_se_prio(rt_se) < rt_rq->highest_prio);
553                 if (rt_se_prio(rt_se) == rt_rq->highest_prio) {
554                         /* recalculate */
555                         array = &rt_rq->active;
556                         rt_rq->highest_prio =
557                                 sched_find_first_bit(array->bitmap);
558                 } /* otherwise leave rq->highest prio alone */
559         } else
560                 rt_rq->highest_prio = MAX_RT_PRIO;
561 #endif
562 #ifdef CONFIG_SMP
563         if (rt_se->nr_cpus_allowed > 1) {
564                 struct rq *rq = rq_of_rt_rq(rt_rq);
565                 rq->rt.rt_nr_migratory--;
566         }
567
568         if (rt_rq->highest_prio != highest_prio) {
569                 struct rq *rq = rq_of_rt_rq(rt_rq);
570
571                 if (rq->online)
572                         cpupri_set(&rq->rd->cpupri, rq->cpu,
573                                    rt_rq->highest_prio);
574         }
575
576         update_rt_migration(rq_of_rt_rq(rt_rq));
577 #endif /* CONFIG_SMP */
578 #ifdef CONFIG_RT_GROUP_SCHED
579         if (rt_se_boosted(rt_se))
580                 rt_rq->rt_nr_boosted--;
581
582         WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
583 #endif
584 }
585
586 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se)
587 {
588         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
589         struct rt_prio_array *array = &rt_rq->active;
590         struct rt_rq *group_rq = group_rt_rq(rt_se);
591         struct list_head *queue = array->queue + rt_se_prio(rt_se);
592
593         /*
594          * Don't enqueue the group if its throttled, or when empty.
595          * The latter is a consequence of the former when a child group
596          * get throttled and the current group doesn't have any other
597          * active members.
598          */
599         if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
600                 return;
601
602         if (rt_se->nr_cpus_allowed == 1)
603                 list_add(&rt_se->run_list, queue);
604         else
605                 list_add_tail(&rt_se->run_list, queue);
606
607         __set_bit(rt_se_prio(rt_se), array->bitmap);
608
609         inc_rt_tasks(rt_se, rt_rq);
610 }
611
612 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
613 {
614         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
615         struct rt_prio_array *array = &rt_rq->active;
616
617         list_del_init(&rt_se->run_list);
618         if (list_empty(array->queue + rt_se_prio(rt_se)))
619                 __clear_bit(rt_se_prio(rt_se), array->bitmap);
620
621         dec_rt_tasks(rt_se, rt_rq);
622 }
623
624 /*
625  * Because the prio of an upper entry depends on the lower
626  * entries, we must remove entries top - down.
627  */
628 static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
629 {
630         struct sched_rt_entity *back = NULL;
631
632         for_each_sched_rt_entity(rt_se) {
633                 rt_se->back = back;
634                 back = rt_se;
635         }
636
637         for (rt_se = back; rt_se; rt_se = rt_se->back) {
638                 if (on_rt_rq(rt_se))
639                         __dequeue_rt_entity(rt_se);
640         }
641 }
642
643 static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
644 {
645         dequeue_rt_stack(rt_se);
646         for_each_sched_rt_entity(rt_se)
647                 __enqueue_rt_entity(rt_se);
648 }
649
650 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
651 {
652         dequeue_rt_stack(rt_se);
653
654         for_each_sched_rt_entity(rt_se) {
655                 struct rt_rq *rt_rq = group_rt_rq(rt_se);
656
657                 if (rt_rq && rt_rq->rt_nr_running)
658                         __enqueue_rt_entity(rt_se);
659         }
660 }
661
662 /*
663  * Adding/removing a task to/from a priority array:
664  */
665 static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
666 {
667         struct sched_rt_entity *rt_se = &p->rt;
668
669         if (wakeup)
670                 rt_se->timeout = 0;
671
672         enqueue_rt_entity(rt_se);
673 }
674
675 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
676 {
677         struct sched_rt_entity *rt_se = &p->rt;
678
679         update_curr_rt(rq);
680         dequeue_rt_entity(rt_se);
681 }
682
683 /*
684  * Put task to the end of the run list without the overhead of dequeue
685  * followed by enqueue.
686  */
687 static
688 void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
689 {
690         struct rt_prio_array *array = &rt_rq->active;
691         struct list_head *queue = array->queue + rt_se_prio(rt_se);
692
693         if (on_rt_rq(rt_se)) {
694                 list_del_init(&rt_se->run_list);
695                 list_add_tail(&rt_se->run_list,
696                               array->queue + rt_se_prio(rt_se));
697         }
698 }
699
700 static void requeue_task_rt(struct rq *rq, struct task_struct *p)
701 {
702         struct sched_rt_entity *rt_se = &p->rt;
703         struct rt_rq *rt_rq;
704
705         for_each_sched_rt_entity(rt_se) {
706                 rt_rq = rt_rq_of_se(rt_se);
707                 requeue_rt_entity(rt_rq, rt_se);
708         }
709 }
710
711 static void yield_task_rt(struct rq *rq)
712 {
713         requeue_task_rt(rq, rq->curr);
714 }
715
716 #ifdef CONFIG_SMP
717 static int find_lowest_rq(struct task_struct *task);
718
719 static int select_task_rq_rt(struct task_struct *p, int sync)
720 {
721         struct rq *rq = task_rq(p);
722
723         /*
724          * If the current task is an RT task, then
725          * try to see if we can wake this RT task up on another
726          * runqueue. Otherwise simply start this RT task
727          * on its current runqueue.
728          *
729          * We want to avoid overloading runqueues. Even if
730          * the RT task is of higher priority than the current RT task.
731          * RT tasks behave differently than other tasks. If
732          * one gets preempted, we try to push it off to another queue.
733          * So trying to keep a preempting RT task on the same
734          * cache hot CPU will force the running RT task to
735          * a cold CPU. So we waste all the cache for the lower
736          * RT task in hopes of saving some of a RT task
737          * that is just being woken and probably will have
738          * cold cache anyway.
739          */
740         if (unlikely(rt_task(rq->curr)) &&
741             (p->rt.nr_cpus_allowed > 1)) {
742                 int cpu = find_lowest_rq(p);
743
744                 return (cpu == -1) ? task_cpu(p) : cpu;
745         }
746
747         /*
748          * Otherwise, just let it ride on the affined RQ and the
749          * post-schedule router will push the preempted task away
750          */
751         return task_cpu(p);
752 }
753 #endif /* CONFIG_SMP */
754
755 /*
756  * Preempt the current task with a newly woken task if needed:
757  */
758 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
759 {
760         if (p->prio < rq->curr->prio) {
761                 resched_task(rq->curr);
762                 return;
763         }
764
765 #ifdef CONFIG_SMP
766         /*
767          * If:
768          *
769          * - the newly woken task is of equal priority to the current task
770          * - the newly woken task is non-migratable while current is migratable
771          * - current will be preempted on the next reschedule
772          *
773          * we should check to see if current can readily move to a different
774          * cpu.  If so, we will reschedule to allow the push logic to try
775          * to move current somewhere else, making room for our non-migratable
776          * task.
777          */
778         if((p->prio == rq->curr->prio)
779            && p->rt.nr_cpus_allowed == 1
780            && rq->curr->rt.nr_cpus_allowed != 1) {
781                 cpumask_t mask;
782
783                 if (cpupri_find(&rq->rd->cpupri, rq->curr, &mask))
784                         /*
785                          * There appears to be other cpus that can accept
786                          * current, so lets reschedule to try and push it away
787                          */
788                         resched_task(rq->curr);
789         }
790 #endif
791 }
792
793 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
794                                                    struct rt_rq *rt_rq)
795 {
796         struct rt_prio_array *array = &rt_rq->active;
797         struct sched_rt_entity *next = NULL;
798         struct list_head *queue;
799         int idx;
800
801         idx = sched_find_first_bit(array->bitmap);
802         BUG_ON(idx >= MAX_RT_PRIO);
803
804         queue = array->queue + idx;
805         next = list_entry(queue->next, struct sched_rt_entity, run_list);
806
807         return next;
808 }
809
810 static struct task_struct *pick_next_task_rt(struct rq *rq)
811 {
812         struct sched_rt_entity *rt_se;
813         struct task_struct *p;
814         struct rt_rq *rt_rq;
815
816         rt_rq = &rq->rt;
817
818         if (unlikely(!rt_rq->rt_nr_running))
819                 return NULL;
820
821         if (rt_rq_throttled(rt_rq))
822                 return NULL;
823
824         do {
825                 rt_se = pick_next_rt_entity(rq, rt_rq);
826                 BUG_ON(!rt_se);
827                 rt_rq = group_rt_rq(rt_se);
828         } while (rt_rq);
829
830         p = rt_task_of(rt_se);
831         p->se.exec_start = rq->clock;
832         return p;
833 }
834
835 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
836 {
837         update_curr_rt(rq);
838         p->se.exec_start = 0;
839 }
840
841 #ifdef CONFIG_SMP
842
843 /* Only try algorithms three times */
844 #define RT_MAX_TRIES 3
845
846 static int double_lock_balance(struct rq *this_rq, struct rq *busiest);
847 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
848
849 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
850 {
851         if (!task_running(rq, p) &&
852             (cpu < 0 || cpu_isset(cpu, p->cpus_allowed)) &&
853             (p->rt.nr_cpus_allowed > 1))
854                 return 1;
855         return 0;
856 }
857
858 /* Return the second highest RT task, NULL otherwise */
859 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
860 {
861         struct task_struct *next = NULL;
862         struct sched_rt_entity *rt_se;
863         struct rt_prio_array *array;
864         struct rt_rq *rt_rq;
865         int idx;
866
867         for_each_leaf_rt_rq(rt_rq, rq) {
868                 array = &rt_rq->active;
869                 idx = sched_find_first_bit(array->bitmap);
870  next_idx:
871                 if (idx >= MAX_RT_PRIO)
872                         continue;
873                 if (next && next->prio < idx)
874                         continue;
875                 list_for_each_entry(rt_se, array->queue + idx, run_list) {
876                         struct task_struct *p = rt_task_of(rt_se);
877                         if (pick_rt_task(rq, p, cpu)) {
878                                 next = p;
879                                 break;
880                         }
881                 }
882                 if (!next) {
883                         idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
884                         goto next_idx;
885                 }
886         }
887
888         return next;
889 }
890
891 static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);
892
893 static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask)
894 {
895         int first;
896
897         /* "this_cpu" is cheaper to preempt than a remote processor */
898         if ((this_cpu != -1) && cpu_isset(this_cpu, *mask))
899                 return this_cpu;
900
901         first = first_cpu(*mask);
902         if (first != NR_CPUS)
903                 return first;
904
905         return -1;
906 }
907
908 static int find_lowest_rq(struct task_struct *task)
909 {
910         struct sched_domain *sd;
911         cpumask_t *lowest_mask = &__get_cpu_var(local_cpu_mask);
912         int this_cpu = smp_processor_id();
913         int cpu      = task_cpu(task);
914
915         if (task->rt.nr_cpus_allowed == 1)
916                 return -1; /* No other targets possible */
917
918         if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
919                 return -1; /* No targets found */
920
921         /*
922          * At this point we have built a mask of cpus representing the
923          * lowest priority tasks in the system.  Now we want to elect
924          * the best one based on our affinity and topology.
925          *
926          * We prioritize the last cpu that the task executed on since
927          * it is most likely cache-hot in that location.
928          */
929         if (cpu_isset(cpu, *lowest_mask))
930                 return cpu;
931
932         /*
933          * Otherwise, we consult the sched_domains span maps to figure
934          * out which cpu is logically closest to our hot cache data.
935          */
936         if (this_cpu == cpu)
937                 this_cpu = -1; /* Skip this_cpu opt if the same */
938
939         for_each_domain(cpu, sd) {
940                 if (sd->flags & SD_WAKE_AFFINE) {
941                         cpumask_t domain_mask;
942                         int       best_cpu;
943
944                         cpus_and(domain_mask, sd->span, *lowest_mask);
945
946                         best_cpu = pick_optimal_cpu(this_cpu,
947                                                     &domain_mask);
948                         if (best_cpu != -1)
949                                 return best_cpu;
950                 }
951         }
952
953         /*
954          * And finally, if there were no matches within the domains
955          * just give the caller *something* to work with from the compatible
956          * locations.
957          */
958         return pick_optimal_cpu(this_cpu, lowest_mask);
959 }
960
961 /* Will lock the rq it finds */
962 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
963 {
964         struct rq *lowest_rq = NULL;
965         int tries;
966         int cpu;
967
968         for (tries = 0; tries < RT_MAX_TRIES; tries++) {
969                 cpu = find_lowest_rq(task);
970
971                 if ((cpu == -1) || (cpu == rq->cpu))
972                         break;
973
974                 lowest_rq = cpu_rq(cpu);
975
976                 /* if the prio of this runqueue changed, try again */
977                 if (double_lock_balance(rq, lowest_rq)) {
978                         /*
979                          * We had to unlock the run queue. In
980                          * the mean time, task could have
981                          * migrated already or had its affinity changed.
982                          * Also make sure that it wasn't scheduled on its rq.
983                          */
984                         if (unlikely(task_rq(task) != rq ||
985                                      !cpu_isset(lowest_rq->cpu,
986                                                 task->cpus_allowed) ||
987                                      task_running(rq, task) ||
988                                      !task->se.on_rq)) {
989
990                                 spin_unlock(&lowest_rq->lock);
991                                 lowest_rq = NULL;
992                                 break;
993                         }
994                 }
995
996                 /* If this rq is still suitable use it. */
997                 if (lowest_rq->rt.highest_prio > task->prio)
998                         break;
999
1000                 /* try again */
1001                 spin_unlock(&lowest_rq->lock);
1002                 lowest_rq = NULL;
1003         }
1004
1005         return lowest_rq;
1006 }
1007
1008 /*
1009  * If the current CPU has more than one RT task, see if the non
1010  * running task can migrate over to a CPU that is running a task
1011  * of lesser priority.
1012  */
1013 static int push_rt_task(struct rq *rq)
1014 {
1015         struct task_struct *next_task;
1016         struct rq *lowest_rq;
1017         int ret = 0;
1018         int paranoid = RT_MAX_TRIES;
1019
1020         if (!rq->rt.overloaded)
1021                 return 0;
1022
1023         next_task = pick_next_highest_task_rt(rq, -1);
1024         if (!next_task)
1025                 return 0;
1026
1027  retry:
1028         if (unlikely(next_task == rq->curr)) {
1029                 WARN_ON(1);
1030                 return 0;
1031         }
1032
1033         /*
1034          * It's possible that the next_task slipped in of
1035          * higher priority than current. If that's the case
1036          * just reschedule current.
1037          */
1038         if (unlikely(next_task->prio < rq->curr->prio)) {
1039                 resched_task(rq->curr);
1040                 return 0;
1041         }
1042
1043         /* We might release rq lock */
1044         get_task_struct(next_task);
1045
1046         /* find_lock_lowest_rq locks the rq if found */
1047         lowest_rq = find_lock_lowest_rq(next_task, rq);
1048         if (!lowest_rq) {
1049                 struct task_struct *task;
1050                 /*
1051                  * find lock_lowest_rq releases rq->lock
1052                  * so it is possible that next_task has changed.
1053                  * If it has, then try again.
1054                  */
1055                 task = pick_next_highest_task_rt(rq, -1);
1056                 if (unlikely(task != next_task) && task && paranoid--) {
1057                         put_task_struct(next_task);
1058                         next_task = task;
1059                         goto retry;
1060                 }
1061                 goto out;
1062         }
1063
1064         deactivate_task(rq, next_task, 0);
1065         set_task_cpu(next_task, lowest_rq->cpu);
1066         activate_task(lowest_rq, next_task, 0);
1067
1068         resched_task(lowest_rq->curr);
1069
1070         spin_unlock(&lowest_rq->lock);
1071
1072         ret = 1;
1073 out:
1074         put_task_struct(next_task);
1075
1076         return ret;
1077 }
1078
1079 /*
1080  * TODO: Currently we just use the second highest prio task on
1081  *       the queue, and stop when it can't migrate (or there's
1082  *       no more RT tasks).  There may be a case where a lower
1083  *       priority RT task has a different affinity than the
1084  *       higher RT task. In this case the lower RT task could
1085  *       possibly be able to migrate where as the higher priority
1086  *       RT task could not.  We currently ignore this issue.
1087  *       Enhancements are welcome!
1088  */
1089 static void push_rt_tasks(struct rq *rq)
1090 {
1091         /* push_rt_task will return true if it moved an RT */
1092         while (push_rt_task(rq))
1093                 ;
1094 }
1095
1096 static int pull_rt_task(struct rq *this_rq)
1097 {
1098         int this_cpu = this_rq->cpu, ret = 0, cpu;
1099         struct task_struct *p, *next;
1100         struct rq *src_rq;
1101
1102         if (likely(!rt_overloaded(this_rq)))
1103                 return 0;
1104
1105         next = pick_next_task_rt(this_rq);
1106
1107         for_each_cpu_mask(cpu, this_rq->rd->rto_mask) {
1108                 if (this_cpu == cpu)
1109                         continue;
1110
1111                 src_rq = cpu_rq(cpu);
1112                 /*
1113                  * We can potentially drop this_rq's lock in
1114                  * double_lock_balance, and another CPU could
1115                  * steal our next task - hence we must cause
1116                  * the caller to recalculate the next task
1117                  * in that case:
1118                  */
1119                 if (double_lock_balance(this_rq, src_rq)) {
1120                         struct task_struct *old_next = next;
1121
1122                         next = pick_next_task_rt(this_rq);
1123                         if (next != old_next)
1124                                 ret = 1;
1125                 }
1126
1127                 /*
1128                  * Are there still pullable RT tasks?
1129                  */
1130                 if (src_rq->rt.rt_nr_running <= 1)
1131                         goto skip;
1132
1133                 p = pick_next_highest_task_rt(src_rq, this_cpu);
1134
1135                 /*
1136                  * Do we have an RT task that preempts
1137                  * the to-be-scheduled task?
1138                  */
1139                 if (p && (!next || (p->prio < next->prio))) {
1140                         WARN_ON(p == src_rq->curr);
1141                         WARN_ON(!p->se.on_rq);
1142
1143                         /*
1144                          * There's a chance that p is higher in priority
1145                          * than what's currently running on its cpu.
1146                          * This is just that p is wakeing up and hasn't
1147                          * had a chance to schedule. We only pull
1148                          * p if it is lower in priority than the
1149                          * current task on the run queue or
1150                          * this_rq next task is lower in prio than
1151                          * the current task on that rq.
1152                          */
1153                         if (p->prio < src_rq->curr->prio ||
1154                             (next && next->prio < src_rq->curr->prio))
1155                                 goto skip;
1156
1157                         ret = 1;
1158
1159                         deactivate_task(src_rq, p, 0);
1160                         set_task_cpu(p, this_cpu);
1161                         activate_task(this_rq, p, 0);
1162                         /*
1163                          * We continue with the search, just in
1164                          * case there's an even higher prio task
1165                          * in another runqueue. (low likelyhood
1166                          * but possible)
1167                          *
1168                          * Update next so that we won't pick a task
1169                          * on another cpu with a priority lower (or equal)
1170                          * than the one we just picked.
1171                          */
1172                         next = p;
1173
1174                 }
1175  skip:
1176                 spin_unlock(&src_rq->lock);
1177         }
1178
1179         return ret;
1180 }
1181
1182 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1183 {
1184         /* Try to pull RT tasks here if we lower this rq's prio */
1185         if (unlikely(rt_task(prev)) && rq->rt.highest_prio > prev->prio)
1186                 pull_rt_task(rq);
1187 }
1188
1189 static void post_schedule_rt(struct rq *rq)
1190 {
1191         /*
1192          * If we have more than one rt_task queued, then
1193          * see if we can push the other rt_tasks off to other CPUS.
1194          * Note we may release the rq lock, and since
1195          * the lock was owned by prev, we need to release it
1196          * first via finish_lock_switch and then reaquire it here.
1197          */
1198         if (unlikely(rq->rt.overloaded)) {
1199                 spin_lock_irq(&rq->lock);
1200                 push_rt_tasks(rq);
1201                 spin_unlock_irq(&rq->lock);
1202         }
1203 }
1204
1205 /*
1206  * If we are not running and we are not going to reschedule soon, we should
1207  * try to push tasks away now
1208  */
1209 static void task_wake_up_rt(struct rq *rq, struct task_struct *p)
1210 {
1211         if (!task_running(rq, p) &&
1212             !test_tsk_need_resched(rq->curr) &&
1213             rq->rt.overloaded)
1214                 push_rt_tasks(rq);
1215 }
1216
1217 static unsigned long
1218 load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
1219                 unsigned long max_load_move,
1220                 struct sched_domain *sd, enum cpu_idle_type idle,
1221                 int *all_pinned, int *this_best_prio)
1222 {
1223         /* don't touch RT tasks */
1224         return 0;
1225 }
1226
1227 static int
1228 move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
1229                  struct sched_domain *sd, enum cpu_idle_type idle)
1230 {
1231         /* don't touch RT tasks */
1232         return 0;
1233 }
1234
1235 static void set_cpus_allowed_rt(struct task_struct *p,
1236                                 const cpumask_t *new_mask)
1237 {
1238         int weight = cpus_weight(*new_mask);
1239
1240         BUG_ON(!rt_task(p));
1241
1242         /*
1243          * Update the migration status of the RQ if we have an RT task
1244          * which is running AND changing its weight value.
1245          */
1246         if (p->se.on_rq && (weight != p->rt.nr_cpus_allowed)) {
1247                 struct rq *rq = task_rq(p);
1248
1249                 if ((p->rt.nr_cpus_allowed <= 1) && (weight > 1)) {
1250                         rq->rt.rt_nr_migratory++;
1251                 } else if ((p->rt.nr_cpus_allowed > 1) && (weight <= 1)) {
1252                         BUG_ON(!rq->rt.rt_nr_migratory);
1253                         rq->rt.rt_nr_migratory--;
1254                 }
1255
1256                 update_rt_migration(rq);
1257         }
1258
1259         p->cpus_allowed    = *new_mask;
1260         p->rt.nr_cpus_allowed = weight;
1261 }
1262
1263 /* Assumes rq->lock is held */
1264 static void rq_online_rt(struct rq *rq)
1265 {
1266         if (rq->rt.overloaded)
1267                 rt_set_overload(rq);
1268
1269         __enable_runtime(rq);
1270
1271         cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio);
1272 }
1273
1274 /* Assumes rq->lock is held */
1275 static void rq_offline_rt(struct rq *rq)
1276 {
1277         if (rq->rt.overloaded)
1278                 rt_clear_overload(rq);
1279
1280         __disable_runtime(rq);
1281
1282         cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1283 }
1284
1285 /*
1286  * When switch from the rt queue, we bring ourselves to a position
1287  * that we might want to pull RT tasks from other runqueues.
1288  */
1289 static void switched_from_rt(struct rq *rq, struct task_struct *p,
1290                            int running)
1291 {
1292         /*
1293          * If there are other RT tasks then we will reschedule
1294          * and the scheduling of the other RT tasks will handle
1295          * the balancing. But if we are the last RT task
1296          * we may need to handle the pulling of RT tasks
1297          * now.
1298          */
1299         if (!rq->rt.rt_nr_running)
1300                 pull_rt_task(rq);
1301 }
1302 #endif /* CONFIG_SMP */
1303
1304 /*
1305  * When switching a task to RT, we may overload the runqueue
1306  * with RT tasks. In this case we try to push them off to
1307  * other runqueues.
1308  */
1309 static void switched_to_rt(struct rq *rq, struct task_struct *p,
1310                            int running)
1311 {
1312         int check_resched = 1;
1313
1314         /*
1315          * If we are already running, then there's nothing
1316          * that needs to be done. But if we are not running
1317          * we may need to preempt the current running task.
1318          * If that current running task is also an RT task
1319          * then see if we can move to another run queue.
1320          */
1321         if (!running) {
1322 #ifdef CONFIG_SMP
1323                 if (rq->rt.overloaded && push_rt_task(rq) &&
1324                     /* Don't resched if we changed runqueues */
1325                     rq != task_rq(p))
1326                         check_resched = 0;
1327 #endif /* CONFIG_SMP */
1328                 if (check_resched && p->prio < rq->curr->prio)
1329                         resched_task(rq->curr);
1330         }
1331 }
1332
1333 /*
1334  * Priority of the task has changed. This may cause
1335  * us to initiate a push or pull.
1336  */
1337 static void prio_changed_rt(struct rq *rq, struct task_struct *p,
1338                             int oldprio, int running)
1339 {
1340         if (running) {
1341 #ifdef CONFIG_SMP
1342                 /*
1343                  * If our priority decreases while running, we
1344                  * may need to pull tasks to this runqueue.
1345                  */
1346                 if (oldprio < p->prio)
1347                         pull_rt_task(rq);
1348                 /*
1349                  * If there's a higher priority task waiting to run
1350                  * then reschedule. Note, the above pull_rt_task
1351                  * can release the rq lock and p could migrate.
1352                  * Only reschedule if p is still on the same runqueue.
1353                  */
1354                 if (p->prio > rq->rt.highest_prio && rq->curr == p)
1355                         resched_task(p);
1356 #else
1357                 /* For UP simply resched on drop of prio */
1358                 if (oldprio < p->prio)
1359                         resched_task(p);
1360 #endif /* CONFIG_SMP */
1361         } else {
1362                 /*
1363                  * This task is not running, but if it is
1364                  * greater than the current running task
1365                  * then reschedule.
1366                  */
1367                 if (p->prio < rq->curr->prio)
1368                         resched_task(rq->curr);
1369         }
1370 }
1371
1372 static void watchdog(struct rq *rq, struct task_struct *p)
1373 {
1374         unsigned long soft, hard;
1375
1376         if (!p->signal)
1377                 return;
1378
1379         soft = p->signal->rlim[RLIMIT_RTTIME].rlim_cur;
1380         hard = p->signal->rlim[RLIMIT_RTTIME].rlim_max;
1381
1382         if (soft != RLIM_INFINITY) {
1383                 unsigned long next;
1384
1385                 p->rt.timeout++;
1386                 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1387                 if (p->rt.timeout > next)
1388                         p->it_sched_expires = p->se.sum_exec_runtime;
1389         }
1390 }
1391
1392 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1393 {
1394         update_curr_rt(rq);
1395
1396         watchdog(rq, p);
1397
1398         /*
1399          * RR tasks need a special form of timeslice management.
1400          * FIFO tasks have no timeslices.
1401          */
1402         if (p->policy != SCHED_RR)
1403                 return;
1404
1405         if (--p->rt.time_slice)
1406                 return;
1407
1408         p->rt.time_slice = DEF_TIMESLICE;
1409
1410         /*
1411          * Requeue to the end of queue if we are not the only element
1412          * on the queue:
1413          */
1414         if (p->rt.run_list.prev != p->rt.run_list.next) {
1415                 requeue_task_rt(rq, p);
1416                 set_tsk_need_resched(p);
1417         }
1418 }
1419
1420 static void set_curr_task_rt(struct rq *rq)
1421 {
1422         struct task_struct *p = rq->curr;
1423
1424         p->se.exec_start = rq->clock;
1425 }
1426
1427 static const struct sched_class rt_sched_class = {
1428         .next                   = &fair_sched_class,
1429         .enqueue_task           = enqueue_task_rt,
1430         .dequeue_task           = dequeue_task_rt,
1431         .yield_task             = yield_task_rt,
1432 #ifdef CONFIG_SMP
1433         .select_task_rq         = select_task_rq_rt,
1434 #endif /* CONFIG_SMP */
1435
1436         .check_preempt_curr     = check_preempt_curr_rt,
1437
1438         .pick_next_task         = pick_next_task_rt,
1439         .put_prev_task          = put_prev_task_rt,
1440
1441 #ifdef CONFIG_SMP
1442         .load_balance           = load_balance_rt,
1443         .move_one_task          = move_one_task_rt,
1444         .set_cpus_allowed       = set_cpus_allowed_rt,
1445         .rq_online              = rq_online_rt,
1446         .rq_offline             = rq_offline_rt,
1447         .pre_schedule           = pre_schedule_rt,
1448         .post_schedule          = post_schedule_rt,
1449         .task_wake_up           = task_wake_up_rt,
1450         .switched_from          = switched_from_rt,
1451 #endif
1452
1453         .set_curr_task          = set_curr_task_rt,
1454         .task_tick              = task_tick_rt,
1455
1456         .prio_changed           = prio_changed_rt,
1457         .switched_to            = switched_to_rt,
1458 };
1459
1460 #ifdef CONFIG_SCHED_DEBUG
1461 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
1462
1463 static void print_rt_stats(struct seq_file *m, int cpu)
1464 {
1465         struct rt_rq *rt_rq;
1466
1467         rcu_read_lock();
1468         for_each_leaf_rt_rq(rt_rq, cpu_rq(cpu))
1469                 print_rt_rq(m, cpu, rt_rq);
1470         rcu_read_unlock();
1471 }
1472 #endif