sched: remove some old cpuset logic
[deliverable/linux.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 cpu_set(rq->cpu, rq->rd->rto_mask);
16 /*
17 * Make sure the mask is visible before we set
18 * the overload count. That is checked to determine
19 * if we should look at the mask. It would be a shame
20 * if we looked at the mask, but the mask was not
21 * updated yet.
22 */
23 wmb();
24 atomic_inc(&rq->rd->rto_count);
25 }
26
27 static inline void rt_clear_overload(struct rq *rq)
28 {
29 /* the order here really doesn't matter */
30 atomic_dec(&rq->rd->rto_count);
31 cpu_clear(rq->cpu, rq->rd->rto_mask);
32 }
33
34 static void update_rt_migration(struct rq *rq)
35 {
36 if (rq->rt.rt_nr_migratory && (rq->rt.rt_nr_running > 1)) {
37 if (!rq->rt.overloaded) {
38 rt_set_overload(rq);
39 rq->rt.overloaded = 1;
40 }
41 } else if (rq->rt.overloaded) {
42 rt_clear_overload(rq);
43 rq->rt.overloaded = 0;
44 }
45 }
46 #endif /* CONFIG_SMP */
47
48 /*
49 * Update the current task's runtime statistics. Skip current tasks that
50 * are not in our scheduling class.
51 */
52 static void update_curr_rt(struct rq *rq)
53 {
54 struct task_struct *curr = rq->curr;
55 u64 delta_exec;
56
57 if (!task_has_rt_policy(curr))
58 return;
59
60 delta_exec = rq->clock - curr->se.exec_start;
61 if (unlikely((s64)delta_exec < 0))
62 delta_exec = 0;
63
64 schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec));
65
66 curr->se.sum_exec_runtime += delta_exec;
67 curr->se.exec_start = rq->clock;
68 cpuacct_charge(curr, delta_exec);
69 }
70
71 static inline void inc_rt_tasks(struct task_struct *p, struct rq *rq)
72 {
73 WARN_ON(!rt_task(p));
74 rq->rt.rt_nr_running++;
75 #ifdef CONFIG_SMP
76 if (p->prio < rq->rt.highest_prio)
77 rq->rt.highest_prio = p->prio;
78 if (p->nr_cpus_allowed > 1)
79 rq->rt.rt_nr_migratory++;
80
81 update_rt_migration(rq);
82 #endif /* CONFIG_SMP */
83 }
84
85 static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq)
86 {
87 WARN_ON(!rt_task(p));
88 WARN_ON(!rq->rt.rt_nr_running);
89 rq->rt.rt_nr_running--;
90 #ifdef CONFIG_SMP
91 if (rq->rt.rt_nr_running) {
92 struct rt_prio_array *array;
93
94 WARN_ON(p->prio < rq->rt.highest_prio);
95 if (p->prio == rq->rt.highest_prio) {
96 /* recalculate */
97 array = &rq->rt.active;
98 rq->rt.highest_prio =
99 sched_find_first_bit(array->bitmap);
100 } /* otherwise leave rq->highest prio alone */
101 } else
102 rq->rt.highest_prio = MAX_RT_PRIO;
103 if (p->nr_cpus_allowed > 1)
104 rq->rt.rt_nr_migratory--;
105
106 update_rt_migration(rq);
107 #endif /* CONFIG_SMP */
108 }
109
110 static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
111 {
112 struct rt_prio_array *array = &rq->rt.active;
113
114 list_add_tail(&p->run_list, array->queue + p->prio);
115 __set_bit(p->prio, array->bitmap);
116 inc_cpu_load(rq, p->se.load.weight);
117
118 inc_rt_tasks(p, rq);
119 }
120
121 /*
122 * Adding/removing a task to/from a priority array:
123 */
124 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
125 {
126 struct rt_prio_array *array = &rq->rt.active;
127
128 update_curr_rt(rq);
129
130 list_del(&p->run_list);
131 if (list_empty(array->queue + p->prio))
132 __clear_bit(p->prio, array->bitmap);
133 dec_cpu_load(rq, p->se.load.weight);
134
135 dec_rt_tasks(p, rq);
136 }
137
138 /*
139 * Put task to the end of the run list without the overhead of dequeue
140 * followed by enqueue.
141 */
142 static void requeue_task_rt(struct rq *rq, struct task_struct *p)
143 {
144 struct rt_prio_array *array = &rq->rt.active;
145
146 list_move_tail(&p->run_list, array->queue + p->prio);
147 }
148
149 static void
150 yield_task_rt(struct rq *rq)
151 {
152 requeue_task_rt(rq, rq->curr);
153 }
154
155 #ifdef CONFIG_SMP
156 static int find_lowest_rq(struct task_struct *task);
157
158 static int select_task_rq_rt(struct task_struct *p, int sync)
159 {
160 struct rq *rq = task_rq(p);
161
162 /*
163 * If the current task is an RT task, then
164 * try to see if we can wake this RT task up on another
165 * runqueue. Otherwise simply start this RT task
166 * on its current runqueue.
167 *
168 * We want to avoid overloading runqueues. Even if
169 * the RT task is of higher priority than the current RT task.
170 * RT tasks behave differently than other tasks. If
171 * one gets preempted, we try to push it off to another queue.
172 * So trying to keep a preempting RT task on the same
173 * cache hot CPU will force the running RT task to
174 * a cold CPU. So we waste all the cache for the lower
175 * RT task in hopes of saving some of a RT task
176 * that is just being woken and probably will have
177 * cold cache anyway.
178 */
179 if (unlikely(rt_task(rq->curr)) &&
180 (p->nr_cpus_allowed > 1)) {
181 int cpu = find_lowest_rq(p);
182
183 return (cpu == -1) ? task_cpu(p) : cpu;
184 }
185
186 /*
187 * Otherwise, just let it ride on the affined RQ and the
188 * post-schedule router will push the preempted task away
189 */
190 return task_cpu(p);
191 }
192 #endif /* CONFIG_SMP */
193
194 /*
195 * Preempt the current task with a newly woken task if needed:
196 */
197 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
198 {
199 if (p->prio < rq->curr->prio)
200 resched_task(rq->curr);
201 }
202
203 static struct task_struct *pick_next_task_rt(struct rq *rq)
204 {
205 struct rt_prio_array *array = &rq->rt.active;
206 struct task_struct *next;
207 struct list_head *queue;
208 int idx;
209
210 idx = sched_find_first_bit(array->bitmap);
211 if (idx >= MAX_RT_PRIO)
212 return NULL;
213
214 queue = array->queue + idx;
215 next = list_entry(queue->next, struct task_struct, run_list);
216
217 next->se.exec_start = rq->clock;
218
219 return next;
220 }
221
222 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
223 {
224 update_curr_rt(rq);
225 p->se.exec_start = 0;
226 }
227
228 #ifdef CONFIG_SMP
229 /* Only try algorithms three times */
230 #define RT_MAX_TRIES 3
231
232 static int double_lock_balance(struct rq *this_rq, struct rq *busiest);
233 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
234
235 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
236 {
237 if (!task_running(rq, p) &&
238 (cpu < 0 || cpu_isset(cpu, p->cpus_allowed)) &&
239 (p->nr_cpus_allowed > 1))
240 return 1;
241 return 0;
242 }
243
244 /* Return the second highest RT task, NULL otherwise */
245 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
246 {
247 struct rt_prio_array *array = &rq->rt.active;
248 struct task_struct *next;
249 struct list_head *queue;
250 int idx;
251
252 if (likely(rq->rt.rt_nr_running < 2))
253 return NULL;
254
255 idx = sched_find_first_bit(array->bitmap);
256 if (unlikely(idx >= MAX_RT_PRIO)) {
257 WARN_ON(1); /* rt_nr_running is bad */
258 return NULL;
259 }
260
261 queue = array->queue + idx;
262 BUG_ON(list_empty(queue));
263
264 next = list_entry(queue->next, struct task_struct, run_list);
265 if (unlikely(pick_rt_task(rq, next, cpu)))
266 goto out;
267
268 if (queue->next->next != queue) {
269 /* same prio task */
270 next = list_entry(queue->next->next, struct task_struct,
271 run_list);
272 if (pick_rt_task(rq, next, cpu))
273 goto out;
274 }
275
276 retry:
277 /* slower, but more flexible */
278 idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
279 if (unlikely(idx >= MAX_RT_PRIO))
280 return NULL;
281
282 queue = array->queue + idx;
283 BUG_ON(list_empty(queue));
284
285 list_for_each_entry(next, queue, run_list) {
286 if (pick_rt_task(rq, next, cpu))
287 goto out;
288 }
289
290 goto retry;
291
292 out:
293 return next;
294 }
295
296 static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);
297
298 static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
299 {
300 int lowest_prio = -1;
301 int lowest_cpu = -1;
302 int count = 0;
303 int cpu;
304
305 cpus_and(*lowest_mask, task_rq(task)->rd->online, task->cpus_allowed);
306
307 /*
308 * Scan each rq for the lowest prio.
309 */
310 for_each_cpu_mask(cpu, *lowest_mask) {
311 struct rq *rq = cpu_rq(cpu);
312
313 /* We look for lowest RT prio or non-rt CPU */
314 if (rq->rt.highest_prio >= MAX_RT_PRIO) {
315 /*
316 * if we already found a low RT queue
317 * and now we found this non-rt queue
318 * clear the mask and set our bit.
319 * Otherwise just return the queue as is
320 * and the count==1 will cause the algorithm
321 * to use the first bit found.
322 */
323 if (lowest_cpu != -1) {
324 cpus_clear(*lowest_mask);
325 cpu_set(rq->cpu, *lowest_mask);
326 }
327 return 1;
328 }
329
330 /* no locking for now */
331 if ((rq->rt.highest_prio > task->prio)
332 && (rq->rt.highest_prio >= lowest_prio)) {
333 if (rq->rt.highest_prio > lowest_prio) {
334 /* new low - clear old data */
335 lowest_prio = rq->rt.highest_prio;
336 lowest_cpu = cpu;
337 count = 0;
338 }
339 count++;
340 } else
341 cpu_clear(cpu, *lowest_mask);
342 }
343
344 /*
345 * Clear out all the set bits that represent
346 * runqueues that were of higher prio than
347 * the lowest_prio.
348 */
349 if (lowest_cpu > 0) {
350 /*
351 * Perhaps we could add another cpumask op to
352 * zero out bits. Like cpu_zero_bits(cpumask, nrbits);
353 * Then that could be optimized to use memset and such.
354 */
355 for_each_cpu_mask(cpu, *lowest_mask) {
356 if (cpu >= lowest_cpu)
357 break;
358 cpu_clear(cpu, *lowest_mask);
359 }
360 }
361
362 return count;
363 }
364
365 static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask)
366 {
367 int first;
368
369 /* "this_cpu" is cheaper to preempt than a remote processor */
370 if ((this_cpu != -1) && cpu_isset(this_cpu, *mask))
371 return this_cpu;
372
373 first = first_cpu(*mask);
374 if (first != NR_CPUS)
375 return first;
376
377 return -1;
378 }
379
380 static int find_lowest_rq(struct task_struct *task)
381 {
382 struct sched_domain *sd;
383 cpumask_t *lowest_mask = &__get_cpu_var(local_cpu_mask);
384 int this_cpu = smp_processor_id();
385 int cpu = task_cpu(task);
386 int count = find_lowest_cpus(task, lowest_mask);
387
388 if (!count)
389 return -1; /* No targets found */
390
391 /*
392 * There is no sense in performing an optimal search if only one
393 * target is found.
394 */
395 if (count == 1)
396 return first_cpu(*lowest_mask);
397
398 /*
399 * At this point we have built a mask of cpus representing the
400 * lowest priority tasks in the system. Now we want to elect
401 * the best one based on our affinity and topology.
402 *
403 * We prioritize the last cpu that the task executed on since
404 * it is most likely cache-hot in that location.
405 */
406 if (cpu_isset(cpu, *lowest_mask))
407 return cpu;
408
409 /*
410 * Otherwise, we consult the sched_domains span maps to figure
411 * out which cpu is logically closest to our hot cache data.
412 */
413 if (this_cpu == cpu)
414 this_cpu = -1; /* Skip this_cpu opt if the same */
415
416 for_each_domain(cpu, sd) {
417 if (sd->flags & SD_WAKE_AFFINE) {
418 cpumask_t domain_mask;
419 int best_cpu;
420
421 cpus_and(domain_mask, sd->span, *lowest_mask);
422
423 best_cpu = pick_optimal_cpu(this_cpu,
424 &domain_mask);
425 if (best_cpu != -1)
426 return best_cpu;
427 }
428 }
429
430 /*
431 * And finally, if there were no matches within the domains
432 * just give the caller *something* to work with from the compatible
433 * locations.
434 */
435 return pick_optimal_cpu(this_cpu, lowest_mask);
436 }
437
438 /* Will lock the rq it finds */
439 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
440 {
441 struct rq *lowest_rq = NULL;
442 int tries;
443 int cpu;
444
445 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
446 cpu = find_lowest_rq(task);
447
448 if ((cpu == -1) || (cpu == rq->cpu))
449 break;
450
451 lowest_rq = cpu_rq(cpu);
452
453 /* if the prio of this runqueue changed, try again */
454 if (double_lock_balance(rq, lowest_rq)) {
455 /*
456 * We had to unlock the run queue. In
457 * the mean time, task could have
458 * migrated already or had its affinity changed.
459 * Also make sure that it wasn't scheduled on its rq.
460 */
461 if (unlikely(task_rq(task) != rq ||
462 !cpu_isset(lowest_rq->cpu,
463 task->cpus_allowed) ||
464 task_running(rq, task) ||
465 !task->se.on_rq)) {
466
467 spin_unlock(&lowest_rq->lock);
468 lowest_rq = NULL;
469 break;
470 }
471 }
472
473 /* If this rq is still suitable use it. */
474 if (lowest_rq->rt.highest_prio > task->prio)
475 break;
476
477 /* try again */
478 spin_unlock(&lowest_rq->lock);
479 lowest_rq = NULL;
480 }
481
482 return lowest_rq;
483 }
484
485 /*
486 * If the current CPU has more than one RT task, see if the non
487 * running task can migrate over to a CPU that is running a task
488 * of lesser priority.
489 */
490 static int push_rt_task(struct rq *rq)
491 {
492 struct task_struct *next_task;
493 struct rq *lowest_rq;
494 int ret = 0;
495 int paranoid = RT_MAX_TRIES;
496
497 if (!rq->rt.overloaded)
498 return 0;
499
500 next_task = pick_next_highest_task_rt(rq, -1);
501 if (!next_task)
502 return 0;
503
504 retry:
505 if (unlikely(next_task == rq->curr)) {
506 WARN_ON(1);
507 return 0;
508 }
509
510 /*
511 * It's possible that the next_task slipped in of
512 * higher priority than current. If that's the case
513 * just reschedule current.
514 */
515 if (unlikely(next_task->prio < rq->curr->prio)) {
516 resched_task(rq->curr);
517 return 0;
518 }
519
520 /* We might release rq lock */
521 get_task_struct(next_task);
522
523 /* find_lock_lowest_rq locks the rq if found */
524 lowest_rq = find_lock_lowest_rq(next_task, rq);
525 if (!lowest_rq) {
526 struct task_struct *task;
527 /*
528 * find lock_lowest_rq releases rq->lock
529 * so it is possible that next_task has changed.
530 * If it has, then try again.
531 */
532 task = pick_next_highest_task_rt(rq, -1);
533 if (unlikely(task != next_task) && task && paranoid--) {
534 put_task_struct(next_task);
535 next_task = task;
536 goto retry;
537 }
538 goto out;
539 }
540
541 deactivate_task(rq, next_task, 0);
542 set_task_cpu(next_task, lowest_rq->cpu);
543 activate_task(lowest_rq, next_task, 0);
544
545 resched_task(lowest_rq->curr);
546
547 spin_unlock(&lowest_rq->lock);
548
549 ret = 1;
550 out:
551 put_task_struct(next_task);
552
553 return ret;
554 }
555
556 /*
557 * TODO: Currently we just use the second highest prio task on
558 * the queue, and stop when it can't migrate (or there's
559 * no more RT tasks). There may be a case where a lower
560 * priority RT task has a different affinity than the
561 * higher RT task. In this case the lower RT task could
562 * possibly be able to migrate where as the higher priority
563 * RT task could not. We currently ignore this issue.
564 * Enhancements are welcome!
565 */
566 static void push_rt_tasks(struct rq *rq)
567 {
568 /* push_rt_task will return true if it moved an RT */
569 while (push_rt_task(rq))
570 ;
571 }
572
573 static int pull_rt_task(struct rq *this_rq)
574 {
575 int this_cpu = this_rq->cpu, ret = 0, cpu;
576 struct task_struct *p, *next;
577 struct rq *src_rq;
578
579 if (likely(!rt_overloaded(this_rq)))
580 return 0;
581
582 next = pick_next_task_rt(this_rq);
583
584 for_each_cpu_mask(cpu, this_rq->rd->rto_mask) {
585 if (this_cpu == cpu)
586 continue;
587
588 src_rq = cpu_rq(cpu);
589 /*
590 * We can potentially drop this_rq's lock in
591 * double_lock_balance, and another CPU could
592 * steal our next task - hence we must cause
593 * the caller to recalculate the next task
594 * in that case:
595 */
596 if (double_lock_balance(this_rq, src_rq)) {
597 struct task_struct *old_next = next;
598
599 next = pick_next_task_rt(this_rq);
600 if (next != old_next)
601 ret = 1;
602 }
603
604 /*
605 * Are there still pullable RT tasks?
606 */
607 if (src_rq->rt.rt_nr_running <= 1) {
608 spin_unlock(&src_rq->lock);
609 continue;
610 }
611
612 p = pick_next_highest_task_rt(src_rq, this_cpu);
613
614 /*
615 * Do we have an RT task that preempts
616 * the to-be-scheduled task?
617 */
618 if (p && (!next || (p->prio < next->prio))) {
619 WARN_ON(p == src_rq->curr);
620 WARN_ON(!p->se.on_rq);
621
622 /*
623 * There's a chance that p is higher in priority
624 * than what's currently running on its cpu.
625 * This is just that p is wakeing up and hasn't
626 * had a chance to schedule. We only pull
627 * p if it is lower in priority than the
628 * current task on the run queue or
629 * this_rq next task is lower in prio than
630 * the current task on that rq.
631 */
632 if (p->prio < src_rq->curr->prio ||
633 (next && next->prio < src_rq->curr->prio))
634 goto out;
635
636 ret = 1;
637
638 deactivate_task(src_rq, p, 0);
639 set_task_cpu(p, this_cpu);
640 activate_task(this_rq, p, 0);
641 /*
642 * We continue with the search, just in
643 * case there's an even higher prio task
644 * in another runqueue. (low likelyhood
645 * but possible)
646 *
647 * Update next so that we won't pick a task
648 * on another cpu with a priority lower (or equal)
649 * than the one we just picked.
650 */
651 next = p;
652
653 }
654 out:
655 spin_unlock(&src_rq->lock);
656 }
657
658 return ret;
659 }
660
661 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
662 {
663 /* Try to pull RT tasks here if we lower this rq's prio */
664 if (unlikely(rt_task(prev)) && rq->rt.highest_prio > prev->prio)
665 pull_rt_task(rq);
666 }
667
668 static void post_schedule_rt(struct rq *rq)
669 {
670 /*
671 * If we have more than one rt_task queued, then
672 * see if we can push the other rt_tasks off to other CPUS.
673 * Note we may release the rq lock, and since
674 * the lock was owned by prev, we need to release it
675 * first via finish_lock_switch and then reaquire it here.
676 */
677 if (unlikely(rq->rt.overloaded)) {
678 spin_lock_irq(&rq->lock);
679 push_rt_tasks(rq);
680 spin_unlock_irq(&rq->lock);
681 }
682 }
683
684
685 static void task_wake_up_rt(struct rq *rq, struct task_struct *p)
686 {
687 if (!task_running(rq, p) &&
688 (p->prio >= rq->rt.highest_prio) &&
689 rq->rt.overloaded)
690 push_rt_tasks(rq);
691 }
692
693 static unsigned long
694 load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
695 unsigned long max_load_move,
696 struct sched_domain *sd, enum cpu_idle_type idle,
697 int *all_pinned, int *this_best_prio)
698 {
699 /* don't touch RT tasks */
700 return 0;
701 }
702
703 static int
704 move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
705 struct sched_domain *sd, enum cpu_idle_type idle)
706 {
707 /* don't touch RT tasks */
708 return 0;
709 }
710
711 static void set_cpus_allowed_rt(struct task_struct *p, cpumask_t *new_mask)
712 {
713 int weight = cpus_weight(*new_mask);
714
715 BUG_ON(!rt_task(p));
716
717 /*
718 * Update the migration status of the RQ if we have an RT task
719 * which is running AND changing its weight value.
720 */
721 if (p->se.on_rq && (weight != p->nr_cpus_allowed)) {
722 struct rq *rq = task_rq(p);
723
724 if ((p->nr_cpus_allowed <= 1) && (weight > 1)) {
725 rq->rt.rt_nr_migratory++;
726 } else if ((p->nr_cpus_allowed > 1) && (weight <= 1)) {
727 BUG_ON(!rq->rt.rt_nr_migratory);
728 rq->rt.rt_nr_migratory--;
729 }
730
731 update_rt_migration(rq);
732 }
733
734 p->cpus_allowed = *new_mask;
735 p->nr_cpus_allowed = weight;
736 }
737
738 /* Assumes rq->lock is held */
739 static void join_domain_rt(struct rq *rq)
740 {
741 if (rq->rt.overloaded)
742 rt_set_overload(rq);
743 }
744
745 /* Assumes rq->lock is held */
746 static void leave_domain_rt(struct rq *rq)
747 {
748 if (rq->rt.overloaded)
749 rt_clear_overload(rq);
750 }
751
752 /*
753 * When switch from the rt queue, we bring ourselves to a position
754 * that we might want to pull RT tasks from other runqueues.
755 */
756 static void switched_from_rt(struct rq *rq, struct task_struct *p,
757 int running)
758 {
759 /*
760 * If there are other RT tasks then we will reschedule
761 * and the scheduling of the other RT tasks will handle
762 * the balancing. But if we are the last RT task
763 * we may need to handle the pulling of RT tasks
764 * now.
765 */
766 if (!rq->rt.rt_nr_running)
767 pull_rt_task(rq);
768 }
769 #endif /* CONFIG_SMP */
770
771 /*
772 * When switching a task to RT, we may overload the runqueue
773 * with RT tasks. In this case we try to push them off to
774 * other runqueues.
775 */
776 static void switched_to_rt(struct rq *rq, struct task_struct *p,
777 int running)
778 {
779 int check_resched = 1;
780
781 /*
782 * If we are already running, then there's nothing
783 * that needs to be done. But if we are not running
784 * we may need to preempt the current running task.
785 * If that current running task is also an RT task
786 * then see if we can move to another run queue.
787 */
788 if (!running) {
789 #ifdef CONFIG_SMP
790 if (rq->rt.overloaded && push_rt_task(rq) &&
791 /* Don't resched if we changed runqueues */
792 rq != task_rq(p))
793 check_resched = 0;
794 #endif /* CONFIG_SMP */
795 if (check_resched && p->prio < rq->curr->prio)
796 resched_task(rq->curr);
797 }
798 }
799
800 /*
801 * Priority of the task has changed. This may cause
802 * us to initiate a push or pull.
803 */
804 static void prio_changed_rt(struct rq *rq, struct task_struct *p,
805 int oldprio, int running)
806 {
807 if (running) {
808 #ifdef CONFIG_SMP
809 /*
810 * If our priority decreases while running, we
811 * may need to pull tasks to this runqueue.
812 */
813 if (oldprio < p->prio)
814 pull_rt_task(rq);
815 /*
816 * If there's a higher priority task waiting to run
817 * then reschedule.
818 */
819 if (p->prio > rq->rt.highest_prio)
820 resched_task(p);
821 #else
822 /* For UP simply resched on drop of prio */
823 if (oldprio < p->prio)
824 resched_task(p);
825 #endif /* CONFIG_SMP */
826 } else {
827 /*
828 * This task is not running, but if it is
829 * greater than the current running task
830 * then reschedule.
831 */
832 if (p->prio < rq->curr->prio)
833 resched_task(rq->curr);
834 }
835 }
836
837
838 static void task_tick_rt(struct rq *rq, struct task_struct *p)
839 {
840 update_curr_rt(rq);
841
842 /*
843 * RR tasks need a special form of timeslice management.
844 * FIFO tasks have no timeslices.
845 */
846 if (p->policy != SCHED_RR)
847 return;
848
849 if (--p->time_slice)
850 return;
851
852 p->time_slice = DEF_TIMESLICE;
853
854 /*
855 * Requeue to the end of queue if we are not the only element
856 * on the queue:
857 */
858 if (p->run_list.prev != p->run_list.next) {
859 requeue_task_rt(rq, p);
860 set_tsk_need_resched(p);
861 }
862 }
863
864 static void set_curr_task_rt(struct rq *rq)
865 {
866 struct task_struct *p = rq->curr;
867
868 p->se.exec_start = rq->clock;
869 }
870
871 const struct sched_class rt_sched_class = {
872 .next = &fair_sched_class,
873 .enqueue_task = enqueue_task_rt,
874 .dequeue_task = dequeue_task_rt,
875 .yield_task = yield_task_rt,
876 #ifdef CONFIG_SMP
877 .select_task_rq = select_task_rq_rt,
878 #endif /* CONFIG_SMP */
879
880 .check_preempt_curr = check_preempt_curr_rt,
881
882 .pick_next_task = pick_next_task_rt,
883 .put_prev_task = put_prev_task_rt,
884
885 #ifdef CONFIG_SMP
886 .load_balance = load_balance_rt,
887 .move_one_task = move_one_task_rt,
888 .set_cpus_allowed = set_cpus_allowed_rt,
889 .join_domain = join_domain_rt,
890 .leave_domain = leave_domain_rt,
891 .pre_schedule = pre_schedule_rt,
892 .post_schedule = post_schedule_rt,
893 .task_wake_up = task_wake_up_rt,
894 .switched_from = switched_from_rt,
895 #endif
896
897 .set_curr_task = set_curr_task_rt,
898 .task_tick = task_tick_rt,
899
900 .prio_changed = prio_changed_rt,
901 .switched_to = switched_to_rt,
902 };
This page took 0.062952 seconds and 6 git commands to generate.