Commit | Line | Data |
---|---|---|
bb44e5d1 IM |
1 | /* |
2 | * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR | |
3 | * policies) | |
4 | */ | |
5 | ||
4fd29176 SR |
6 | #ifdef CONFIG_SMP |
7 | static cpumask_t rt_overload_mask; | |
8 | static atomic_t rto_count; | |
9 | static inline int rt_overloaded(void) | |
10 | { | |
11 | return atomic_read(&rto_count); | |
12 | } | |
13 | static inline cpumask_t *rt_overload(void) | |
14 | { | |
15 | return &rt_overload_mask; | |
16 | } | |
17 | static inline void rt_set_overload(struct rq *rq) | |
18 | { | |
19 | cpu_set(rq->cpu, rt_overload_mask); | |
20 | /* | |
21 | * Make sure the mask is visible before we set | |
22 | * the overload count. That is checked to determine | |
23 | * if we should look at the mask. It would be a shame | |
24 | * if we looked at the mask, but the mask was not | |
25 | * updated yet. | |
26 | */ | |
27 | wmb(); | |
28 | atomic_inc(&rto_count); | |
29 | } | |
30 | static inline void rt_clear_overload(struct rq *rq) | |
31 | { | |
32 | /* the order here really doesn't matter */ | |
33 | atomic_dec(&rto_count); | |
34 | cpu_clear(rq->cpu, rt_overload_mask); | |
35 | } | |
36 | #endif /* CONFIG_SMP */ | |
37 | ||
bb44e5d1 IM |
38 | /* |
39 | * Update the current task's runtime statistics. Skip current tasks that | |
40 | * are not in our scheduling class. | |
41 | */ | |
a9957449 | 42 | static void update_curr_rt(struct rq *rq) |
bb44e5d1 IM |
43 | { |
44 | struct task_struct *curr = rq->curr; | |
45 | u64 delta_exec; | |
46 | ||
47 | if (!task_has_rt_policy(curr)) | |
48 | return; | |
49 | ||
d281918d | 50 | delta_exec = rq->clock - curr->se.exec_start; |
bb44e5d1 IM |
51 | if (unlikely((s64)delta_exec < 0)) |
52 | delta_exec = 0; | |
6cfb0d5d IM |
53 | |
54 | schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec)); | |
bb44e5d1 IM |
55 | |
56 | curr->se.sum_exec_runtime += delta_exec; | |
d281918d | 57 | curr->se.exec_start = rq->clock; |
d842de87 | 58 | cpuacct_charge(curr, delta_exec); |
bb44e5d1 IM |
59 | } |
60 | ||
63489e45 SR |
61 | static inline void inc_rt_tasks(struct task_struct *p, struct rq *rq) |
62 | { | |
63 | WARN_ON(!rt_task(p)); | |
64 | rq->rt.rt_nr_running++; | |
764a9d6f SR |
65 | #ifdef CONFIG_SMP |
66 | if (p->prio < rq->rt.highest_prio) | |
67 | rq->rt.highest_prio = p->prio; | |
4fd29176 SR |
68 | if (rq->rt.rt_nr_running > 1) |
69 | rt_set_overload(rq); | |
764a9d6f | 70 | #endif /* CONFIG_SMP */ |
63489e45 SR |
71 | } |
72 | ||
73 | static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq) | |
74 | { | |
75 | WARN_ON(!rt_task(p)); | |
76 | WARN_ON(!rq->rt.rt_nr_running); | |
77 | rq->rt.rt_nr_running--; | |
764a9d6f SR |
78 | #ifdef CONFIG_SMP |
79 | if (rq->rt.rt_nr_running) { | |
80 | struct rt_prio_array *array; | |
81 | ||
82 | WARN_ON(p->prio < rq->rt.highest_prio); | |
83 | if (p->prio == rq->rt.highest_prio) { | |
84 | /* recalculate */ | |
85 | array = &rq->rt.active; | |
86 | rq->rt.highest_prio = | |
87 | sched_find_first_bit(array->bitmap); | |
88 | } /* otherwise leave rq->highest prio alone */ | |
89 | } else | |
90 | rq->rt.highest_prio = MAX_RT_PRIO; | |
4fd29176 SR |
91 | if (rq->rt.rt_nr_running < 2) |
92 | rt_clear_overload(rq); | |
764a9d6f | 93 | #endif /* CONFIG_SMP */ |
63489e45 SR |
94 | } |
95 | ||
fd390f6a | 96 | static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup) |
bb44e5d1 IM |
97 | { |
98 | struct rt_prio_array *array = &rq->rt.active; | |
99 | ||
100 | list_add_tail(&p->run_list, array->queue + p->prio); | |
101 | __set_bit(p->prio, array->bitmap); | |
58e2d4ca | 102 | inc_cpu_load(rq, p->se.load.weight); |
63489e45 SR |
103 | |
104 | inc_rt_tasks(p, rq); | |
bb44e5d1 IM |
105 | } |
106 | ||
107 | /* | |
108 | * Adding/removing a task to/from a priority array: | |
109 | */ | |
f02231e5 | 110 | static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep) |
bb44e5d1 IM |
111 | { |
112 | struct rt_prio_array *array = &rq->rt.active; | |
113 | ||
f1e14ef6 | 114 | update_curr_rt(rq); |
bb44e5d1 IM |
115 | |
116 | list_del(&p->run_list); | |
117 | if (list_empty(array->queue + p->prio)) | |
118 | __clear_bit(p->prio, array->bitmap); | |
58e2d4ca | 119 | dec_cpu_load(rq, p->se.load.weight); |
63489e45 SR |
120 | |
121 | dec_rt_tasks(p, rq); | |
bb44e5d1 IM |
122 | } |
123 | ||
124 | /* | |
125 | * Put task to the end of the run list without the overhead of dequeue | |
126 | * followed by enqueue. | |
127 | */ | |
128 | static void requeue_task_rt(struct rq *rq, struct task_struct *p) | |
129 | { | |
130 | struct rt_prio_array *array = &rq->rt.active; | |
131 | ||
132 | list_move_tail(&p->run_list, array->queue + p->prio); | |
133 | } | |
134 | ||
135 | static void | |
4530d7ab | 136 | yield_task_rt(struct rq *rq) |
bb44e5d1 | 137 | { |
4530d7ab | 138 | requeue_task_rt(rq, rq->curr); |
bb44e5d1 IM |
139 | } |
140 | ||
141 | /* | |
142 | * Preempt the current task with a newly woken task if needed: | |
143 | */ | |
144 | static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p) | |
145 | { | |
146 | if (p->prio < rq->curr->prio) | |
147 | resched_task(rq->curr); | |
148 | } | |
149 | ||
fb8d4724 | 150 | static struct task_struct *pick_next_task_rt(struct rq *rq) |
bb44e5d1 IM |
151 | { |
152 | struct rt_prio_array *array = &rq->rt.active; | |
153 | struct task_struct *next; | |
154 | struct list_head *queue; | |
155 | int idx; | |
156 | ||
157 | idx = sched_find_first_bit(array->bitmap); | |
158 | if (idx >= MAX_RT_PRIO) | |
159 | return NULL; | |
160 | ||
161 | queue = array->queue + idx; | |
162 | next = list_entry(queue->next, struct task_struct, run_list); | |
163 | ||
d281918d | 164 | next->se.exec_start = rq->clock; |
bb44e5d1 IM |
165 | |
166 | return next; | |
167 | } | |
168 | ||
31ee529c | 169 | static void put_prev_task_rt(struct rq *rq, struct task_struct *p) |
bb44e5d1 | 170 | { |
f1e14ef6 | 171 | update_curr_rt(rq); |
bb44e5d1 IM |
172 | p->se.exec_start = 0; |
173 | } | |
174 | ||
681f3e68 | 175 | #ifdef CONFIG_SMP |
e8fa1362 SR |
176 | /* Only try algorithms three times */ |
177 | #define RT_MAX_TRIES 3 | |
178 | ||
179 | static int double_lock_balance(struct rq *this_rq, struct rq *busiest); | |
180 | static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep); | |
181 | ||
f65eda4f SR |
182 | static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu) |
183 | { | |
184 | if (!task_running(rq, p) && | |
185 | (cpu < 0 || cpu_isset(cpu, p->cpus_allowed))) | |
186 | return 1; | |
187 | return 0; | |
188 | } | |
189 | ||
e8fa1362 | 190 | /* Return the second highest RT task, NULL otherwise */ |
f65eda4f SR |
191 | static struct task_struct *pick_next_highest_task_rt(struct rq *rq, |
192 | int cpu) | |
e8fa1362 SR |
193 | { |
194 | struct rt_prio_array *array = &rq->rt.active; | |
195 | struct task_struct *next; | |
196 | struct list_head *queue; | |
197 | int idx; | |
198 | ||
199 | assert_spin_locked(&rq->lock); | |
200 | ||
201 | if (likely(rq->rt.rt_nr_running < 2)) | |
202 | return NULL; | |
203 | ||
204 | idx = sched_find_first_bit(array->bitmap); | |
205 | if (unlikely(idx >= MAX_RT_PRIO)) { | |
206 | WARN_ON(1); /* rt_nr_running is bad */ | |
207 | return NULL; | |
208 | } | |
209 | ||
210 | queue = array->queue + idx; | |
f65eda4f SR |
211 | BUG_ON(list_empty(queue)); |
212 | ||
e8fa1362 | 213 | next = list_entry(queue->next, struct task_struct, run_list); |
f65eda4f SR |
214 | if (unlikely(pick_rt_task(rq, next, cpu))) |
215 | goto out; | |
e8fa1362 SR |
216 | |
217 | if (queue->next->next != queue) { | |
218 | /* same prio task */ | |
219 | next = list_entry(queue->next->next, struct task_struct, run_list); | |
f65eda4f SR |
220 | if (pick_rt_task(rq, next, cpu)) |
221 | goto out; | |
e8fa1362 SR |
222 | } |
223 | ||
f65eda4f | 224 | retry: |
e8fa1362 SR |
225 | /* slower, but more flexible */ |
226 | idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1); | |
f65eda4f | 227 | if (unlikely(idx >= MAX_RT_PRIO)) |
e8fa1362 | 228 | return NULL; |
e8fa1362 SR |
229 | |
230 | queue = array->queue + idx; | |
f65eda4f SR |
231 | BUG_ON(list_empty(queue)); |
232 | ||
233 | list_for_each_entry(next, queue, run_list) { | |
234 | if (pick_rt_task(rq, next, cpu)) | |
235 | goto out; | |
236 | } | |
237 | ||
238 | goto retry; | |
e8fa1362 | 239 | |
f65eda4f | 240 | out: |
e8fa1362 SR |
241 | return next; |
242 | } | |
243 | ||
244 | static DEFINE_PER_CPU(cpumask_t, local_cpu_mask); | |
245 | ||
246 | /* Will lock the rq it finds */ | |
247 | static struct rq *find_lock_lowest_rq(struct task_struct *task, | |
248 | struct rq *this_rq) | |
249 | { | |
250 | struct rq *lowest_rq = NULL; | |
251 | int cpu; | |
252 | int tries; | |
253 | cpumask_t *cpu_mask = &__get_cpu_var(local_cpu_mask); | |
254 | ||
255 | cpus_and(*cpu_mask, cpu_online_map, task->cpus_allowed); | |
256 | ||
257 | for (tries = 0; tries < RT_MAX_TRIES; tries++) { | |
258 | /* | |
259 | * Scan each rq for the lowest prio. | |
260 | */ | |
261 | for_each_cpu_mask(cpu, *cpu_mask) { | |
262 | struct rq *rq = &per_cpu(runqueues, cpu); | |
263 | ||
264 | if (cpu == this_rq->cpu) | |
265 | continue; | |
266 | ||
267 | /* We look for lowest RT prio or non-rt CPU */ | |
268 | if (rq->rt.highest_prio >= MAX_RT_PRIO) { | |
269 | lowest_rq = rq; | |
270 | break; | |
271 | } | |
272 | ||
273 | /* no locking for now */ | |
274 | if (rq->rt.highest_prio > task->prio && | |
275 | (!lowest_rq || rq->rt.highest_prio > lowest_rq->rt.highest_prio)) { | |
276 | lowest_rq = rq; | |
277 | } | |
278 | } | |
279 | ||
280 | if (!lowest_rq) | |
281 | break; | |
282 | ||
283 | /* if the prio of this runqueue changed, try again */ | |
284 | if (double_lock_balance(this_rq, lowest_rq)) { | |
285 | /* | |
286 | * We had to unlock the run queue. In | |
287 | * the mean time, task could have | |
288 | * migrated already or had its affinity changed. | |
289 | * Also make sure that it wasn't scheduled on its rq. | |
290 | */ | |
291 | if (unlikely(task_rq(task) != this_rq || | |
292 | !cpu_isset(lowest_rq->cpu, task->cpus_allowed) || | |
293 | task_running(this_rq, task) || | |
294 | !task->se.on_rq)) { | |
295 | spin_unlock(&lowest_rq->lock); | |
296 | lowest_rq = NULL; | |
297 | break; | |
298 | } | |
299 | } | |
300 | ||
301 | /* If this rq is still suitable use it. */ | |
302 | if (lowest_rq->rt.highest_prio > task->prio) | |
303 | break; | |
304 | ||
305 | /* try again */ | |
306 | spin_unlock(&lowest_rq->lock); | |
307 | lowest_rq = NULL; | |
308 | } | |
309 | ||
310 | return lowest_rq; | |
311 | } | |
312 | ||
313 | /* | |
314 | * If the current CPU has more than one RT task, see if the non | |
315 | * running task can migrate over to a CPU that is running a task | |
316 | * of lesser priority. | |
317 | */ | |
318 | static int push_rt_task(struct rq *this_rq) | |
319 | { | |
320 | struct task_struct *next_task; | |
321 | struct rq *lowest_rq; | |
322 | int ret = 0; | |
323 | int paranoid = RT_MAX_TRIES; | |
324 | ||
325 | assert_spin_locked(&this_rq->lock); | |
326 | ||
f65eda4f | 327 | next_task = pick_next_highest_task_rt(this_rq, -1); |
e8fa1362 SR |
328 | if (!next_task) |
329 | return 0; | |
330 | ||
331 | retry: | |
f65eda4f SR |
332 | if (unlikely(next_task == this_rq->curr)) { |
333 | WARN_ON(1); | |
e8fa1362 | 334 | return 0; |
f65eda4f | 335 | } |
e8fa1362 SR |
336 | |
337 | /* | |
338 | * It's possible that the next_task slipped in of | |
339 | * higher priority than current. If that's the case | |
340 | * just reschedule current. | |
341 | */ | |
342 | if (unlikely(next_task->prio < this_rq->curr->prio)) { | |
343 | resched_task(this_rq->curr); | |
344 | return 0; | |
345 | } | |
346 | ||
347 | /* We might release this_rq lock */ | |
348 | get_task_struct(next_task); | |
349 | ||
350 | /* find_lock_lowest_rq locks the rq if found */ | |
351 | lowest_rq = find_lock_lowest_rq(next_task, this_rq); | |
352 | if (!lowest_rq) { | |
353 | struct task_struct *task; | |
354 | /* | |
355 | * find lock_lowest_rq releases this_rq->lock | |
356 | * so it is possible that next_task has changed. | |
357 | * If it has, then try again. | |
358 | */ | |
f65eda4f | 359 | task = pick_next_highest_task_rt(this_rq, -1); |
e8fa1362 SR |
360 | if (unlikely(task != next_task) && task && paranoid--) { |
361 | put_task_struct(next_task); | |
362 | next_task = task; | |
363 | goto retry; | |
364 | } | |
365 | goto out; | |
366 | } | |
367 | ||
368 | assert_spin_locked(&lowest_rq->lock); | |
369 | ||
370 | deactivate_task(this_rq, next_task, 0); | |
371 | set_task_cpu(next_task, lowest_rq->cpu); | |
372 | activate_task(lowest_rq, next_task, 0); | |
373 | ||
374 | resched_task(lowest_rq->curr); | |
375 | ||
376 | spin_unlock(&lowest_rq->lock); | |
377 | ||
378 | ret = 1; | |
379 | out: | |
380 | put_task_struct(next_task); | |
381 | ||
382 | return ret; | |
383 | } | |
384 | ||
385 | /* | |
386 | * TODO: Currently we just use the second highest prio task on | |
387 | * the queue, and stop when it can't migrate (or there's | |
388 | * no more RT tasks). There may be a case where a lower | |
389 | * priority RT task has a different affinity than the | |
390 | * higher RT task. In this case the lower RT task could | |
391 | * possibly be able to migrate where as the higher priority | |
392 | * RT task could not. We currently ignore this issue. | |
393 | * Enhancements are welcome! | |
394 | */ | |
395 | static void push_rt_tasks(struct rq *rq) | |
396 | { | |
397 | /* push_rt_task will return true if it moved an RT */ | |
398 | while (push_rt_task(rq)) | |
399 | ; | |
400 | } | |
401 | ||
f65eda4f SR |
402 | static int pull_rt_task(struct rq *this_rq) |
403 | { | |
404 | struct task_struct *next; | |
405 | struct task_struct *p; | |
406 | struct rq *src_rq; | |
407 | cpumask_t *rto_cpumask; | |
408 | int this_cpu = this_rq->cpu; | |
409 | int cpu; | |
410 | int ret = 0; | |
411 | ||
412 | assert_spin_locked(&this_rq->lock); | |
413 | ||
414 | /* | |
415 | * If cpusets are used, and we have overlapping | |
416 | * run queue cpusets, then this algorithm may not catch all. | |
417 | * This is just the price you pay on trying to keep | |
418 | * dirtying caches down on large SMP machines. | |
419 | */ | |
420 | if (likely(!rt_overloaded())) | |
421 | return 0; | |
422 | ||
423 | next = pick_next_task_rt(this_rq); | |
424 | ||
425 | rto_cpumask = rt_overload(); | |
426 | ||
427 | for_each_cpu_mask(cpu, *rto_cpumask) { | |
428 | if (this_cpu == cpu) | |
429 | continue; | |
430 | ||
431 | src_rq = cpu_rq(cpu); | |
432 | if (unlikely(src_rq->rt.rt_nr_running <= 1)) { | |
433 | /* | |
434 | * It is possible that overlapping cpusets | |
435 | * will miss clearing a non overloaded runqueue. | |
436 | * Clear it now. | |
437 | */ | |
438 | if (double_lock_balance(this_rq, src_rq)) { | |
439 | /* unlocked our runqueue lock */ | |
440 | struct task_struct *old_next = next; | |
441 | next = pick_next_task_rt(this_rq); | |
442 | if (next != old_next) | |
443 | ret = 1; | |
444 | } | |
445 | if (likely(src_rq->rt.rt_nr_running <= 1)) | |
446 | /* | |
447 | * Small chance that this_rq->curr changed | |
448 | * but it's really harmless here. | |
449 | */ | |
450 | rt_clear_overload(this_rq); | |
451 | else | |
452 | /* | |
453 | * Heh, the src_rq is now overloaded, since | |
454 | * we already have the src_rq lock, go straight | |
455 | * to pulling tasks from it. | |
456 | */ | |
457 | goto try_pulling; | |
458 | spin_unlock(&src_rq->lock); | |
459 | continue; | |
460 | } | |
461 | ||
462 | /* | |
463 | * We can potentially drop this_rq's lock in | |
464 | * double_lock_balance, and another CPU could | |
465 | * steal our next task - hence we must cause | |
466 | * the caller to recalculate the next task | |
467 | * in that case: | |
468 | */ | |
469 | if (double_lock_balance(this_rq, src_rq)) { | |
470 | struct task_struct *old_next = next; | |
471 | next = pick_next_task_rt(this_rq); | |
472 | if (next != old_next) | |
473 | ret = 1; | |
474 | } | |
475 | ||
476 | /* | |
477 | * Are there still pullable RT tasks? | |
478 | */ | |
479 | if (src_rq->rt.rt_nr_running <= 1) { | |
480 | spin_unlock(&src_rq->lock); | |
481 | continue; | |
482 | } | |
483 | ||
484 | try_pulling: | |
485 | p = pick_next_highest_task_rt(src_rq, this_cpu); | |
486 | ||
487 | /* | |
488 | * Do we have an RT task that preempts | |
489 | * the to-be-scheduled task? | |
490 | */ | |
491 | if (p && (!next || (p->prio < next->prio))) { | |
492 | WARN_ON(p == src_rq->curr); | |
493 | WARN_ON(!p->se.on_rq); | |
494 | ||
495 | /* | |
496 | * There's a chance that p is higher in priority | |
497 | * than what's currently running on its cpu. | |
498 | * This is just that p is wakeing up and hasn't | |
499 | * had a chance to schedule. We only pull | |
500 | * p if it is lower in priority than the | |
501 | * current task on the run queue or | |
502 | * this_rq next task is lower in prio than | |
503 | * the current task on that rq. | |
504 | */ | |
505 | if (p->prio < src_rq->curr->prio || | |
506 | (next && next->prio < src_rq->curr->prio)) | |
507 | goto bail; | |
508 | ||
509 | ret = 1; | |
510 | ||
511 | deactivate_task(src_rq, p, 0); | |
512 | set_task_cpu(p, this_cpu); | |
513 | activate_task(this_rq, p, 0); | |
514 | /* | |
515 | * We continue with the search, just in | |
516 | * case there's an even higher prio task | |
517 | * in another runqueue. (low likelyhood | |
518 | * but possible) | |
519 | */ | |
520 | ||
521 | /* | |
522 | * Update next so that we won't pick a task | |
523 | * on another cpu with a priority lower (or equal) | |
524 | * than the one we just picked. | |
525 | */ | |
526 | next = p; | |
527 | ||
528 | } | |
529 | bail: | |
530 | spin_unlock(&src_rq->lock); | |
531 | } | |
532 | ||
533 | return ret; | |
534 | } | |
535 | ||
536 | static void schedule_balance_rt(struct rq *rq, | |
537 | struct task_struct *prev) | |
538 | { | |
539 | /* Try to pull RT tasks here if we lower this rq's prio */ | |
540 | if (unlikely(rt_task(prev)) && | |
541 | rq->rt.highest_prio > prev->prio) | |
542 | pull_rt_task(rq); | |
543 | } | |
544 | ||
e8fa1362 SR |
545 | static void schedule_tail_balance_rt(struct rq *rq) |
546 | { | |
547 | /* | |
548 | * If we have more than one rt_task queued, then | |
549 | * see if we can push the other rt_tasks off to other CPUS. | |
550 | * Note we may release the rq lock, and since | |
551 | * the lock was owned by prev, we need to release it | |
552 | * first via finish_lock_switch and then reaquire it here. | |
553 | */ | |
554 | if (unlikely(rq->rt.rt_nr_running > 1)) { | |
555 | spin_lock_irq(&rq->lock); | |
556 | push_rt_tasks(rq); | |
557 | spin_unlock_irq(&rq->lock); | |
558 | } | |
559 | } | |
560 | ||
4642dafd SR |
561 | |
562 | static void wakeup_balance_rt(struct rq *rq, struct task_struct *p) | |
563 | { | |
564 | if (unlikely(rt_task(p)) && | |
565 | !task_running(rq, p) && | |
566 | (p->prio >= rq->curr->prio)) | |
567 | push_rt_tasks(rq); | |
568 | } | |
569 | ||
bb44e5d1 IM |
570 | /* |
571 | * Load-balancing iterator. Note: while the runqueue stays locked | |
572 | * during the whole iteration, the current task might be | |
573 | * dequeued so the iterator has to be dequeue-safe. Here we | |
574 | * achieve that by always pre-iterating before returning | |
575 | * the current task: | |
576 | */ | |
577 | static struct task_struct *load_balance_start_rt(void *arg) | |
578 | { | |
579 | struct rq *rq = arg; | |
580 | struct rt_prio_array *array = &rq->rt.active; | |
581 | struct list_head *head, *curr; | |
582 | struct task_struct *p; | |
583 | int idx; | |
584 | ||
585 | idx = sched_find_first_bit(array->bitmap); | |
586 | if (idx >= MAX_RT_PRIO) | |
587 | return NULL; | |
588 | ||
589 | head = array->queue + idx; | |
590 | curr = head->prev; | |
591 | ||
592 | p = list_entry(curr, struct task_struct, run_list); | |
593 | ||
594 | curr = curr->prev; | |
595 | ||
596 | rq->rt.rt_load_balance_idx = idx; | |
597 | rq->rt.rt_load_balance_head = head; | |
598 | rq->rt.rt_load_balance_curr = curr; | |
599 | ||
600 | return p; | |
601 | } | |
602 | ||
603 | static struct task_struct *load_balance_next_rt(void *arg) | |
604 | { | |
605 | struct rq *rq = arg; | |
606 | struct rt_prio_array *array = &rq->rt.active; | |
607 | struct list_head *head, *curr; | |
608 | struct task_struct *p; | |
609 | int idx; | |
610 | ||
611 | idx = rq->rt.rt_load_balance_idx; | |
612 | head = rq->rt.rt_load_balance_head; | |
613 | curr = rq->rt.rt_load_balance_curr; | |
614 | ||
615 | /* | |
616 | * If we arrived back to the head again then | |
617 | * iterate to the next queue (if any): | |
618 | */ | |
619 | if (unlikely(head == curr)) { | |
620 | int next_idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1); | |
621 | ||
622 | if (next_idx >= MAX_RT_PRIO) | |
623 | return NULL; | |
624 | ||
625 | idx = next_idx; | |
626 | head = array->queue + idx; | |
627 | curr = head->prev; | |
628 | ||
629 | rq->rt.rt_load_balance_idx = idx; | |
630 | rq->rt.rt_load_balance_head = head; | |
631 | } | |
632 | ||
633 | p = list_entry(curr, struct task_struct, run_list); | |
634 | ||
635 | curr = curr->prev; | |
636 | ||
637 | rq->rt.rt_load_balance_curr = curr; | |
638 | ||
639 | return p; | |
640 | } | |
641 | ||
43010659 | 642 | static unsigned long |
bb44e5d1 | 643 | load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest, |
e1d1484f PW |
644 | unsigned long max_load_move, |
645 | struct sched_domain *sd, enum cpu_idle_type idle, | |
646 | int *all_pinned, int *this_best_prio) | |
bb44e5d1 | 647 | { |
bb44e5d1 IM |
648 | struct rq_iterator rt_rq_iterator; |
649 | ||
bb44e5d1 IM |
650 | rt_rq_iterator.start = load_balance_start_rt; |
651 | rt_rq_iterator.next = load_balance_next_rt; | |
652 | /* pass 'busiest' rq argument into | |
653 | * load_balance_[start|next]_rt iterators | |
654 | */ | |
655 | rt_rq_iterator.arg = busiest; | |
656 | ||
e1d1484f PW |
657 | return balance_tasks(this_rq, this_cpu, busiest, max_load_move, sd, |
658 | idle, all_pinned, this_best_prio, &rt_rq_iterator); | |
659 | } | |
660 | ||
661 | static int | |
662 | move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest, | |
663 | struct sched_domain *sd, enum cpu_idle_type idle) | |
664 | { | |
665 | struct rq_iterator rt_rq_iterator; | |
666 | ||
667 | rt_rq_iterator.start = load_balance_start_rt; | |
668 | rt_rq_iterator.next = load_balance_next_rt; | |
669 | rt_rq_iterator.arg = busiest; | |
bb44e5d1 | 670 | |
e1d1484f PW |
671 | return iter_move_one_task(this_rq, this_cpu, busiest, sd, idle, |
672 | &rt_rq_iterator); | |
bb44e5d1 | 673 | } |
e8fa1362 SR |
674 | #else /* CONFIG_SMP */ |
675 | # define schedule_tail_balance_rt(rq) do { } while (0) | |
f65eda4f | 676 | # define schedule_balance_rt(rq, prev) do { } while (0) |
4642dafd | 677 | # define wakeup_balance_rt(rq, p) do { } while (0) |
e8fa1362 | 678 | #endif /* CONFIG_SMP */ |
bb44e5d1 IM |
679 | |
680 | static void task_tick_rt(struct rq *rq, struct task_struct *p) | |
681 | { | |
67e2be02 PZ |
682 | update_curr_rt(rq); |
683 | ||
bb44e5d1 IM |
684 | /* |
685 | * RR tasks need a special form of timeslice management. | |
686 | * FIFO tasks have no timeslices. | |
687 | */ | |
688 | if (p->policy != SCHED_RR) | |
689 | return; | |
690 | ||
691 | if (--p->time_slice) | |
692 | return; | |
693 | ||
a4ec24b4 | 694 | p->time_slice = DEF_TIMESLICE; |
bb44e5d1 | 695 | |
98fbc798 DA |
696 | /* |
697 | * Requeue to the end of queue if we are not the only element | |
698 | * on the queue: | |
699 | */ | |
700 | if (p->run_list.prev != p->run_list.next) { | |
701 | requeue_task_rt(rq, p); | |
702 | set_tsk_need_resched(p); | |
703 | } | |
bb44e5d1 IM |
704 | } |
705 | ||
83b699ed SV |
706 | static void set_curr_task_rt(struct rq *rq) |
707 | { | |
708 | struct task_struct *p = rq->curr; | |
709 | ||
710 | p->se.exec_start = rq->clock; | |
711 | } | |
712 | ||
5522d5d5 IM |
713 | const struct sched_class rt_sched_class = { |
714 | .next = &fair_sched_class, | |
bb44e5d1 IM |
715 | .enqueue_task = enqueue_task_rt, |
716 | .dequeue_task = dequeue_task_rt, | |
717 | .yield_task = yield_task_rt, | |
718 | ||
719 | .check_preempt_curr = check_preempt_curr_rt, | |
720 | ||
721 | .pick_next_task = pick_next_task_rt, | |
722 | .put_prev_task = put_prev_task_rt, | |
723 | ||
681f3e68 | 724 | #ifdef CONFIG_SMP |
bb44e5d1 | 725 | .load_balance = load_balance_rt, |
e1d1484f | 726 | .move_one_task = move_one_task_rt, |
681f3e68 | 727 | #endif |
bb44e5d1 | 728 | |
83b699ed | 729 | .set_curr_task = set_curr_task_rt, |
bb44e5d1 | 730 | .task_tick = task_tick_rt, |
bb44e5d1 | 731 | }; |