Loading...
1/*
2 * Deadline Scheduling Class (SCHED_DEADLINE)
3 *
4 * Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS).
5 *
6 * Tasks that periodically executes their instances for less than their
7 * runtime won't miss any of their deadlines.
8 * Tasks that are not periodic or sporadic or that tries to execute more
9 * than their reserved bandwidth will be slowed down (and may potentially
10 * miss some of their deadlines), and won't affect any other task.
11 *
12 * Copyright (C) 2012 Dario Faggioli <raistlin@linux.it>,
13 * Juri Lelli <juri.lelli@gmail.com>,
14 * Michael Trimarchi <michael@amarulasolutions.com>,
15 * Fabio Checconi <fchecconi@gmail.com>
16 */
17#include "sched.h"
18
19#include <linux/slab.h>
20
21struct dl_bandwidth def_dl_bandwidth;
22
23static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
24{
25 return container_of(dl_se, struct task_struct, dl);
26}
27
28static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq)
29{
30 return container_of(dl_rq, struct rq, dl);
31}
32
33static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se)
34{
35 struct task_struct *p = dl_task_of(dl_se);
36 struct rq *rq = task_rq(p);
37
38 return &rq->dl;
39}
40
41static inline int on_dl_rq(struct sched_dl_entity *dl_se)
42{
43 return !RB_EMPTY_NODE(&dl_se->rb_node);
44}
45
46static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
47{
48 struct sched_dl_entity *dl_se = &p->dl;
49
50 return dl_rq->rb_leftmost == &dl_se->rb_node;
51}
52
53void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime)
54{
55 raw_spin_lock_init(&dl_b->dl_runtime_lock);
56 dl_b->dl_period = period;
57 dl_b->dl_runtime = runtime;
58}
59
60void init_dl_bw(struct dl_bw *dl_b)
61{
62 raw_spin_lock_init(&dl_b->lock);
63 raw_spin_lock(&def_dl_bandwidth.dl_runtime_lock);
64 if (global_rt_runtime() == RUNTIME_INF)
65 dl_b->bw = -1;
66 else
67 dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime());
68 raw_spin_unlock(&def_dl_bandwidth.dl_runtime_lock);
69 dl_b->total_bw = 0;
70}
71
72void init_dl_rq(struct dl_rq *dl_rq)
73{
74 dl_rq->rb_root = RB_ROOT;
75
76#ifdef CONFIG_SMP
77 /* zero means no -deadline tasks */
78 dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0;
79
80 dl_rq->dl_nr_migratory = 0;
81 dl_rq->overloaded = 0;
82 dl_rq->pushable_dl_tasks_root = RB_ROOT;
83#else
84 init_dl_bw(&dl_rq->dl_bw);
85#endif
86}
87
88#ifdef CONFIG_SMP
89
90static inline int dl_overloaded(struct rq *rq)
91{
92 return atomic_read(&rq->rd->dlo_count);
93}
94
95static inline void dl_set_overload(struct rq *rq)
96{
97 if (!rq->online)
98 return;
99
100 cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask);
101 /*
102 * Must be visible before the overload count is
103 * set (as in sched_rt.c).
104 *
105 * Matched by the barrier in pull_dl_task().
106 */
107 smp_wmb();
108 atomic_inc(&rq->rd->dlo_count);
109}
110
111static inline void dl_clear_overload(struct rq *rq)
112{
113 if (!rq->online)
114 return;
115
116 atomic_dec(&rq->rd->dlo_count);
117 cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask);
118}
119
120static void update_dl_migration(struct dl_rq *dl_rq)
121{
122 if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_running > 1) {
123 if (!dl_rq->overloaded) {
124 dl_set_overload(rq_of_dl_rq(dl_rq));
125 dl_rq->overloaded = 1;
126 }
127 } else if (dl_rq->overloaded) {
128 dl_clear_overload(rq_of_dl_rq(dl_rq));
129 dl_rq->overloaded = 0;
130 }
131}
132
133static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
134{
135 struct task_struct *p = dl_task_of(dl_se);
136
137 if (tsk_nr_cpus_allowed(p) > 1)
138 dl_rq->dl_nr_migratory++;
139
140 update_dl_migration(dl_rq);
141}
142
143static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
144{
145 struct task_struct *p = dl_task_of(dl_se);
146
147 if (tsk_nr_cpus_allowed(p) > 1)
148 dl_rq->dl_nr_migratory--;
149
150 update_dl_migration(dl_rq);
151}
152
153/*
154 * The list of pushable -deadline task is not a plist, like in
155 * sched_rt.c, it is an rb-tree with tasks ordered by deadline.
156 */
157static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
158{
159 struct dl_rq *dl_rq = &rq->dl;
160 struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_node;
161 struct rb_node *parent = NULL;
162 struct task_struct *entry;
163 int leftmost = 1;
164
165 BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
166
167 while (*link) {
168 parent = *link;
169 entry = rb_entry(parent, struct task_struct,
170 pushable_dl_tasks);
171 if (dl_entity_preempt(&p->dl, &entry->dl))
172 link = &parent->rb_left;
173 else {
174 link = &parent->rb_right;
175 leftmost = 0;
176 }
177 }
178
179 if (leftmost) {
180 dl_rq->pushable_dl_tasks_leftmost = &p->pushable_dl_tasks;
181 dl_rq->earliest_dl.next = p->dl.deadline;
182 }
183
184 rb_link_node(&p->pushable_dl_tasks, parent, link);
185 rb_insert_color(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
186}
187
188static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
189{
190 struct dl_rq *dl_rq = &rq->dl;
191
192 if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
193 return;
194
195 if (dl_rq->pushable_dl_tasks_leftmost == &p->pushable_dl_tasks) {
196 struct rb_node *next_node;
197
198 next_node = rb_next(&p->pushable_dl_tasks);
199 dl_rq->pushable_dl_tasks_leftmost = next_node;
200 if (next_node) {
201 dl_rq->earliest_dl.next = rb_entry(next_node,
202 struct task_struct, pushable_dl_tasks)->dl.deadline;
203 }
204 }
205
206 rb_erase(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
207 RB_CLEAR_NODE(&p->pushable_dl_tasks);
208}
209
210static inline int has_pushable_dl_tasks(struct rq *rq)
211{
212 return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root);
213}
214
215static int push_dl_task(struct rq *rq);
216
217static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
218{
219 return dl_task(prev);
220}
221
222static DEFINE_PER_CPU(struct callback_head, dl_push_head);
223static DEFINE_PER_CPU(struct callback_head, dl_pull_head);
224
225static void push_dl_tasks(struct rq *);
226static void pull_dl_task(struct rq *);
227
228static inline void queue_push_tasks(struct rq *rq)
229{
230 if (!has_pushable_dl_tasks(rq))
231 return;
232
233 queue_balance_callback(rq, &per_cpu(dl_push_head, rq->cpu), push_dl_tasks);
234}
235
236static inline void queue_pull_task(struct rq *rq)
237{
238 queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task);
239}
240
241static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq);
242
243static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p)
244{
245 struct rq *later_rq = NULL;
246
247 later_rq = find_lock_later_rq(p, rq);
248 if (!later_rq) {
249 int cpu;
250
251 /*
252 * If we cannot preempt any rq, fall back to pick any
253 * online cpu.
254 */
255 cpu = cpumask_any_and(cpu_active_mask, tsk_cpus_allowed(p));
256 if (cpu >= nr_cpu_ids) {
257 /*
258 * Fail to find any suitable cpu.
259 * The task will never come back!
260 */
261 BUG_ON(dl_bandwidth_enabled());
262
263 /*
264 * If admission control is disabled we
265 * try a little harder to let the task
266 * run.
267 */
268 cpu = cpumask_any(cpu_active_mask);
269 }
270 later_rq = cpu_rq(cpu);
271 double_lock_balance(rq, later_rq);
272 }
273
274 set_task_cpu(p, later_rq->cpu);
275 double_unlock_balance(later_rq, rq);
276
277 return later_rq;
278}
279
280#else
281
282static inline
283void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
284{
285}
286
287static inline
288void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
289{
290}
291
292static inline
293void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
294{
295}
296
297static inline
298void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
299{
300}
301
302static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
303{
304 return false;
305}
306
307static inline void pull_dl_task(struct rq *rq)
308{
309}
310
311static inline void queue_push_tasks(struct rq *rq)
312{
313}
314
315static inline void queue_pull_task(struct rq *rq)
316{
317}
318#endif /* CONFIG_SMP */
319
320static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags);
321static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags);
322static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
323 int flags);
324
325/*
326 * We are being explicitly informed that a new instance is starting,
327 * and this means that:
328 * - the absolute deadline of the entity has to be placed at
329 * current time + relative deadline;
330 * - the runtime of the entity has to be set to the maximum value.
331 *
332 * The capability of specifying such event is useful whenever a -deadline
333 * entity wants to (try to!) synchronize its behaviour with the scheduler's
334 * one, and to (try to!) reconcile itself with its own scheduling
335 * parameters.
336 */
337static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se)
338{
339 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
340 struct rq *rq = rq_of_dl_rq(dl_rq);
341
342 WARN_ON(dl_se->dl_boosted);
343 WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline));
344
345 /*
346 * We are racing with the deadline timer. So, do nothing because
347 * the deadline timer handler will take care of properly recharging
348 * the runtime and postponing the deadline
349 */
350 if (dl_se->dl_throttled)
351 return;
352
353 /*
354 * We use the regular wall clock time to set deadlines in the
355 * future; in fact, we must consider execution overheads (time
356 * spent on hardirq context, etc.).
357 */
358 dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline;
359 dl_se->runtime = dl_se->dl_runtime;
360}
361
362/*
363 * Pure Earliest Deadline First (EDF) scheduling does not deal with the
364 * possibility of a entity lasting more than what it declared, and thus
365 * exhausting its runtime.
366 *
367 * Here we are interested in making runtime overrun possible, but we do
368 * not want a entity which is misbehaving to affect the scheduling of all
369 * other entities.
370 * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
371 * is used, in order to confine each entity within its own bandwidth.
372 *
373 * This function deals exactly with that, and ensures that when the runtime
374 * of a entity is replenished, its deadline is also postponed. That ensures
375 * the overrunning entity can't interfere with other entity in the system and
376 * can't make them miss their deadlines. Reasons why this kind of overruns
377 * could happen are, typically, a entity voluntarily trying to overcome its
378 * runtime, or it just underestimated it during sched_setattr().
379 */
380static void replenish_dl_entity(struct sched_dl_entity *dl_se,
381 struct sched_dl_entity *pi_se)
382{
383 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
384 struct rq *rq = rq_of_dl_rq(dl_rq);
385
386 BUG_ON(pi_se->dl_runtime <= 0);
387
388 /*
389 * This could be the case for a !-dl task that is boosted.
390 * Just go with full inherited parameters.
391 */
392 if (dl_se->dl_deadline == 0) {
393 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
394 dl_se->runtime = pi_se->dl_runtime;
395 }
396
397 if (dl_se->dl_yielded && dl_se->runtime > 0)
398 dl_se->runtime = 0;
399
400 /*
401 * We keep moving the deadline away until we get some
402 * available runtime for the entity. This ensures correct
403 * handling of situations where the runtime overrun is
404 * arbitrary large.
405 */
406 while (dl_se->runtime <= 0) {
407 dl_se->deadline += pi_se->dl_period;
408 dl_se->runtime += pi_se->dl_runtime;
409 }
410
411 /*
412 * At this point, the deadline really should be "in
413 * the future" with respect to rq->clock. If it's
414 * not, we are, for some reason, lagging too much!
415 * Anyway, after having warn userspace abut that,
416 * we still try to keep the things running by
417 * resetting the deadline and the budget of the
418 * entity.
419 */
420 if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
421 printk_deferred_once("sched: DL replenish lagged too much\n");
422 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
423 dl_se->runtime = pi_se->dl_runtime;
424 }
425
426 if (dl_se->dl_yielded)
427 dl_se->dl_yielded = 0;
428 if (dl_se->dl_throttled)
429 dl_se->dl_throttled = 0;
430}
431
432/*
433 * Here we check if --at time t-- an entity (which is probably being
434 * [re]activated or, in general, enqueued) can use its remaining runtime
435 * and its current deadline _without_ exceeding the bandwidth it is
436 * assigned (function returns true if it can't). We are in fact applying
437 * one of the CBS rules: when a task wakes up, if the residual runtime
438 * over residual deadline fits within the allocated bandwidth, then we
439 * can keep the current (absolute) deadline and residual budget without
440 * disrupting the schedulability of the system. Otherwise, we should
441 * refill the runtime and set the deadline a period in the future,
442 * because keeping the current (absolute) deadline of the task would
443 * result in breaking guarantees promised to other tasks (refer to
444 * Documentation/scheduler/sched-deadline.txt for more informations).
445 *
446 * This function returns true if:
447 *
448 * runtime / (deadline - t) > dl_runtime / dl_period ,
449 *
450 * IOW we can't recycle current parameters.
451 *
452 * Notice that the bandwidth check is done against the period. For
453 * task with deadline equal to period this is the same of using
454 * dl_deadline instead of dl_period in the equation above.
455 */
456static bool dl_entity_overflow(struct sched_dl_entity *dl_se,
457 struct sched_dl_entity *pi_se, u64 t)
458{
459 u64 left, right;
460
461 /*
462 * left and right are the two sides of the equation above,
463 * after a bit of shuffling to use multiplications instead
464 * of divisions.
465 *
466 * Note that none of the time values involved in the two
467 * multiplications are absolute: dl_deadline and dl_runtime
468 * are the relative deadline and the maximum runtime of each
469 * instance, runtime is the runtime left for the last instance
470 * and (deadline - t), since t is rq->clock, is the time left
471 * to the (absolute) deadline. Even if overflowing the u64 type
472 * is very unlikely to occur in both cases, here we scale down
473 * as we want to avoid that risk at all. Scaling down by 10
474 * means that we reduce granularity to 1us. We are fine with it,
475 * since this is only a true/false check and, anyway, thinking
476 * of anything below microseconds resolution is actually fiction
477 * (but still we want to give the user that illusion >;).
478 */
479 left = (pi_se->dl_period >> DL_SCALE) * (dl_se->runtime >> DL_SCALE);
480 right = ((dl_se->deadline - t) >> DL_SCALE) *
481 (pi_se->dl_runtime >> DL_SCALE);
482
483 return dl_time_before(right, left);
484}
485
486/*
487 * When a -deadline entity is queued back on the runqueue, its runtime and
488 * deadline might need updating.
489 *
490 * The policy here is that we update the deadline of the entity only if:
491 * - the current deadline is in the past,
492 * - using the remaining runtime with the current deadline would make
493 * the entity exceed its bandwidth.
494 */
495static void update_dl_entity(struct sched_dl_entity *dl_se,
496 struct sched_dl_entity *pi_se)
497{
498 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
499 struct rq *rq = rq_of_dl_rq(dl_rq);
500
501 if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
502 dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) {
503 dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline;
504 dl_se->runtime = pi_se->dl_runtime;
505 }
506}
507
508/*
509 * If the entity depleted all its runtime, and if we want it to sleep
510 * while waiting for some new execution time to become available, we
511 * set the bandwidth enforcement timer to the replenishment instant
512 * and try to activate it.
513 *
514 * Notice that it is important for the caller to know if the timer
515 * actually started or not (i.e., the replenishment instant is in
516 * the future or in the past).
517 */
518static int start_dl_timer(struct task_struct *p)
519{
520 struct sched_dl_entity *dl_se = &p->dl;
521 struct hrtimer *timer = &dl_se->dl_timer;
522 struct rq *rq = task_rq(p);
523 ktime_t now, act;
524 s64 delta;
525
526 lockdep_assert_held(&rq->lock);
527
528 /*
529 * We want the timer to fire at the deadline, but considering
530 * that it is actually coming from rq->clock and not from
531 * hrtimer's time base reading.
532 */
533 act = ns_to_ktime(dl_se->deadline);
534 now = hrtimer_cb_get_time(timer);
535 delta = ktime_to_ns(now) - rq_clock(rq);
536 act = ktime_add_ns(act, delta);
537
538 /*
539 * If the expiry time already passed, e.g., because the value
540 * chosen as the deadline is too small, don't even try to
541 * start the timer in the past!
542 */
543 if (ktime_us_delta(act, now) < 0)
544 return 0;
545
546 /*
547 * !enqueued will guarantee another callback; even if one is already in
548 * progress. This ensures a balanced {get,put}_task_struct().
549 *
550 * The race against __run_timer() clearing the enqueued state is
551 * harmless because we're holding task_rq()->lock, therefore the timer
552 * expiring after we've done the check will wait on its task_rq_lock()
553 * and observe our state.
554 */
555 if (!hrtimer_is_queued(timer)) {
556 get_task_struct(p);
557 hrtimer_start(timer, act, HRTIMER_MODE_ABS);
558 }
559
560 return 1;
561}
562
563/*
564 * This is the bandwidth enforcement timer callback. If here, we know
565 * a task is not on its dl_rq, since the fact that the timer was running
566 * means the task is throttled and needs a runtime replenishment.
567 *
568 * However, what we actually do depends on the fact the task is active,
569 * (it is on its rq) or has been removed from there by a call to
570 * dequeue_task_dl(). In the former case we must issue the runtime
571 * replenishment and add the task back to the dl_rq; in the latter, we just
572 * do nothing but clearing dl_throttled, so that runtime and deadline
573 * updating (and the queueing back to dl_rq) will be done by the
574 * next call to enqueue_task_dl().
575 */
576static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
577{
578 struct sched_dl_entity *dl_se = container_of(timer,
579 struct sched_dl_entity,
580 dl_timer);
581 struct task_struct *p = dl_task_of(dl_se);
582 struct rq_flags rf;
583 struct rq *rq;
584
585 rq = task_rq_lock(p, &rf);
586
587 /*
588 * The task might have changed its scheduling policy to something
589 * different than SCHED_DEADLINE (through switched_from_dl()).
590 */
591 if (!dl_task(p)) {
592 __dl_clear_params(p);
593 goto unlock;
594 }
595
596 /*
597 * The task might have been boosted by someone else and might be in the
598 * boosting/deboosting path, its not throttled.
599 */
600 if (dl_se->dl_boosted)
601 goto unlock;
602
603 /*
604 * Spurious timer due to start_dl_timer() race; or we already received
605 * a replenishment from rt_mutex_setprio().
606 */
607 if (!dl_se->dl_throttled)
608 goto unlock;
609
610 sched_clock_tick();
611 update_rq_clock(rq);
612
613 /*
614 * If the throttle happened during sched-out; like:
615 *
616 * schedule()
617 * deactivate_task()
618 * dequeue_task_dl()
619 * update_curr_dl()
620 * start_dl_timer()
621 * __dequeue_task_dl()
622 * prev->on_rq = 0;
623 *
624 * We can be both throttled and !queued. Replenish the counter
625 * but do not enqueue -- wait for our wakeup to do that.
626 */
627 if (!task_on_rq_queued(p)) {
628 replenish_dl_entity(dl_se, dl_se);
629 goto unlock;
630 }
631
632#ifdef CONFIG_SMP
633 if (unlikely(!rq->online)) {
634 /*
635 * If the runqueue is no longer available, migrate the
636 * task elsewhere. This necessarily changes rq.
637 */
638 lockdep_unpin_lock(&rq->lock, rf.cookie);
639 rq = dl_task_offline_migration(rq, p);
640 rf.cookie = lockdep_pin_lock(&rq->lock);
641
642 /*
643 * Now that the task has been migrated to the new RQ and we
644 * have that locked, proceed as normal and enqueue the task
645 * there.
646 */
647 }
648#endif
649
650 enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
651 if (dl_task(rq->curr))
652 check_preempt_curr_dl(rq, p, 0);
653 else
654 resched_curr(rq);
655
656#ifdef CONFIG_SMP
657 /*
658 * Queueing this task back might have overloaded rq, check if we need
659 * to kick someone away.
660 */
661 if (has_pushable_dl_tasks(rq)) {
662 /*
663 * Nothing relies on rq->lock after this, so its safe to drop
664 * rq->lock.
665 */
666 lockdep_unpin_lock(&rq->lock, rf.cookie);
667 push_dl_task(rq);
668 lockdep_repin_lock(&rq->lock, rf.cookie);
669 }
670#endif
671
672unlock:
673 task_rq_unlock(rq, p, &rf);
674
675 /*
676 * This can free the task_struct, including this hrtimer, do not touch
677 * anything related to that after this.
678 */
679 put_task_struct(p);
680
681 return HRTIMER_NORESTART;
682}
683
684void init_dl_task_timer(struct sched_dl_entity *dl_se)
685{
686 struct hrtimer *timer = &dl_se->dl_timer;
687
688 hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
689 timer->function = dl_task_timer;
690}
691
692static
693int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
694{
695 return (dl_se->runtime <= 0);
696}
697
698extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
699
700/*
701 * Update the current task's runtime statistics (provided it is still
702 * a -deadline task and has not been removed from the dl_rq).
703 */
704static void update_curr_dl(struct rq *rq)
705{
706 struct task_struct *curr = rq->curr;
707 struct sched_dl_entity *dl_se = &curr->dl;
708 u64 delta_exec;
709
710 if (!dl_task(curr) || !on_dl_rq(dl_se))
711 return;
712
713 /*
714 * Consumed budget is computed considering the time as
715 * observed by schedulable tasks (excluding time spent
716 * in hardirq context, etc.). Deadlines are instead
717 * computed using hard walltime. This seems to be the more
718 * natural solution, but the full ramifications of this
719 * approach need further study.
720 */
721 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
722 if (unlikely((s64)delta_exec <= 0)) {
723 if (unlikely(dl_se->dl_yielded))
724 goto throttle;
725 return;
726 }
727
728 /* kick cpufreq (see the comment in kernel/sched/sched.h). */
729 cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_DL);
730
731 schedstat_set(curr->se.statistics.exec_max,
732 max(curr->se.statistics.exec_max, delta_exec));
733
734 curr->se.sum_exec_runtime += delta_exec;
735 account_group_exec_runtime(curr, delta_exec);
736
737 curr->se.exec_start = rq_clock_task(rq);
738 cpuacct_charge(curr, delta_exec);
739
740 sched_rt_avg_update(rq, delta_exec);
741
742 dl_se->runtime -= delta_exec;
743
744throttle:
745 if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
746 dl_se->dl_throttled = 1;
747 __dequeue_task_dl(rq, curr, 0);
748 if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr)))
749 enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
750
751 if (!is_leftmost(curr, &rq->dl))
752 resched_curr(rq);
753 }
754
755 /*
756 * Because -- for now -- we share the rt bandwidth, we need to
757 * account our runtime there too, otherwise actual rt tasks
758 * would be able to exceed the shared quota.
759 *
760 * Account to the root rt group for now.
761 *
762 * The solution we're working towards is having the RT groups scheduled
763 * using deadline servers -- however there's a few nasties to figure
764 * out before that can happen.
765 */
766 if (rt_bandwidth_enabled()) {
767 struct rt_rq *rt_rq = &rq->rt;
768
769 raw_spin_lock(&rt_rq->rt_runtime_lock);
770 /*
771 * We'll let actual RT tasks worry about the overflow here, we
772 * have our own CBS to keep us inline; only account when RT
773 * bandwidth is relevant.
774 */
775 if (sched_rt_bandwidth_account(rt_rq))
776 rt_rq->rt_time += delta_exec;
777 raw_spin_unlock(&rt_rq->rt_runtime_lock);
778 }
779}
780
781#ifdef CONFIG_SMP
782
783static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
784{
785 struct rq *rq = rq_of_dl_rq(dl_rq);
786
787 if (dl_rq->earliest_dl.curr == 0 ||
788 dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
789 dl_rq->earliest_dl.curr = deadline;
790 cpudl_set(&rq->rd->cpudl, rq->cpu, deadline);
791 }
792}
793
794static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
795{
796 struct rq *rq = rq_of_dl_rq(dl_rq);
797
798 /*
799 * Since we may have removed our earliest (and/or next earliest)
800 * task we must recompute them.
801 */
802 if (!dl_rq->dl_nr_running) {
803 dl_rq->earliest_dl.curr = 0;
804 dl_rq->earliest_dl.next = 0;
805 cpudl_clear(&rq->rd->cpudl, rq->cpu);
806 } else {
807 struct rb_node *leftmost = dl_rq->rb_leftmost;
808 struct sched_dl_entity *entry;
809
810 entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
811 dl_rq->earliest_dl.curr = entry->deadline;
812 cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline);
813 }
814}
815
816#else
817
818static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
819static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
820
821#endif /* CONFIG_SMP */
822
823static inline
824void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
825{
826 int prio = dl_task_of(dl_se)->prio;
827 u64 deadline = dl_se->deadline;
828
829 WARN_ON(!dl_prio(prio));
830 dl_rq->dl_nr_running++;
831 add_nr_running(rq_of_dl_rq(dl_rq), 1);
832
833 inc_dl_deadline(dl_rq, deadline);
834 inc_dl_migration(dl_se, dl_rq);
835}
836
837static inline
838void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
839{
840 int prio = dl_task_of(dl_se)->prio;
841
842 WARN_ON(!dl_prio(prio));
843 WARN_ON(!dl_rq->dl_nr_running);
844 dl_rq->dl_nr_running--;
845 sub_nr_running(rq_of_dl_rq(dl_rq), 1);
846
847 dec_dl_deadline(dl_rq, dl_se->deadline);
848 dec_dl_migration(dl_se, dl_rq);
849}
850
851static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
852{
853 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
854 struct rb_node **link = &dl_rq->rb_root.rb_node;
855 struct rb_node *parent = NULL;
856 struct sched_dl_entity *entry;
857 int leftmost = 1;
858
859 BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
860
861 while (*link) {
862 parent = *link;
863 entry = rb_entry(parent, struct sched_dl_entity, rb_node);
864 if (dl_time_before(dl_se->deadline, entry->deadline))
865 link = &parent->rb_left;
866 else {
867 link = &parent->rb_right;
868 leftmost = 0;
869 }
870 }
871
872 if (leftmost)
873 dl_rq->rb_leftmost = &dl_se->rb_node;
874
875 rb_link_node(&dl_se->rb_node, parent, link);
876 rb_insert_color(&dl_se->rb_node, &dl_rq->rb_root);
877
878 inc_dl_tasks(dl_se, dl_rq);
879}
880
881static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
882{
883 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
884
885 if (RB_EMPTY_NODE(&dl_se->rb_node))
886 return;
887
888 if (dl_rq->rb_leftmost == &dl_se->rb_node) {
889 struct rb_node *next_node;
890
891 next_node = rb_next(&dl_se->rb_node);
892 dl_rq->rb_leftmost = next_node;
893 }
894
895 rb_erase(&dl_se->rb_node, &dl_rq->rb_root);
896 RB_CLEAR_NODE(&dl_se->rb_node);
897
898 dec_dl_tasks(dl_se, dl_rq);
899}
900
901static void
902enqueue_dl_entity(struct sched_dl_entity *dl_se,
903 struct sched_dl_entity *pi_se, int flags)
904{
905 BUG_ON(on_dl_rq(dl_se));
906
907 /*
908 * If this is a wakeup or a new instance, the scheduling
909 * parameters of the task might need updating. Otherwise,
910 * we want a replenishment of its runtime.
911 */
912 if (flags & ENQUEUE_WAKEUP)
913 update_dl_entity(dl_se, pi_se);
914 else if (flags & ENQUEUE_REPLENISH)
915 replenish_dl_entity(dl_se, pi_se);
916
917 __enqueue_dl_entity(dl_se);
918}
919
920static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
921{
922 __dequeue_dl_entity(dl_se);
923}
924
925static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
926{
927 struct task_struct *pi_task = rt_mutex_get_top_task(p);
928 struct sched_dl_entity *pi_se = &p->dl;
929
930 /*
931 * Use the scheduling parameters of the top pi-waiter
932 * task if we have one and its (absolute) deadline is
933 * smaller than our one... OTW we keep our runtime and
934 * deadline.
935 */
936 if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) {
937 pi_se = &pi_task->dl;
938 } else if (!dl_prio(p->normal_prio)) {
939 /*
940 * Special case in which we have a !SCHED_DEADLINE task
941 * that is going to be deboosted, but exceedes its
942 * runtime while doing so. No point in replenishing
943 * it, as it's going to return back to its original
944 * scheduling class after this.
945 */
946 BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH);
947 return;
948 }
949
950 /*
951 * If p is throttled, we do nothing. In fact, if it exhausted
952 * its budget it needs a replenishment and, since it now is on
953 * its rq, the bandwidth timer callback (which clearly has not
954 * run yet) will take care of this.
955 */
956 if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH))
957 return;
958
959 enqueue_dl_entity(&p->dl, pi_se, flags);
960
961 if (!task_current(rq, p) && tsk_nr_cpus_allowed(p) > 1)
962 enqueue_pushable_dl_task(rq, p);
963}
964
965static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
966{
967 dequeue_dl_entity(&p->dl);
968 dequeue_pushable_dl_task(rq, p);
969}
970
971static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
972{
973 update_curr_dl(rq);
974 __dequeue_task_dl(rq, p, flags);
975}
976
977/*
978 * Yield task semantic for -deadline tasks is:
979 *
980 * get off from the CPU until our next instance, with
981 * a new runtime. This is of little use now, since we
982 * don't have a bandwidth reclaiming mechanism. Anyway,
983 * bandwidth reclaiming is planned for the future, and
984 * yield_task_dl will indicate that some spare budget
985 * is available for other task instances to use it.
986 */
987static void yield_task_dl(struct rq *rq)
988{
989 /*
990 * We make the task go to sleep until its current deadline by
991 * forcing its runtime to zero. This way, update_curr_dl() stops
992 * it and the bandwidth timer will wake it up and will give it
993 * new scheduling parameters (thanks to dl_yielded=1).
994 */
995 rq->curr->dl.dl_yielded = 1;
996
997 update_rq_clock(rq);
998 update_curr_dl(rq);
999 /*
1000 * Tell update_rq_clock() that we've just updated,
1001 * so we don't do microscopic update in schedule()
1002 * and double the fastpath cost.
1003 */
1004 rq_clock_skip_update(rq, true);
1005}
1006
1007#ifdef CONFIG_SMP
1008
1009static int find_later_rq(struct task_struct *task);
1010
1011static int
1012select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
1013{
1014 struct task_struct *curr;
1015 struct rq *rq;
1016
1017 if (sd_flag != SD_BALANCE_WAKE)
1018 goto out;
1019
1020 rq = cpu_rq(cpu);
1021
1022 rcu_read_lock();
1023 curr = READ_ONCE(rq->curr); /* unlocked access */
1024
1025 /*
1026 * If we are dealing with a -deadline task, we must
1027 * decide where to wake it up.
1028 * If it has a later deadline and the current task
1029 * on this rq can't move (provided the waking task
1030 * can!) we prefer to send it somewhere else. On the
1031 * other hand, if it has a shorter deadline, we
1032 * try to make it stay here, it might be important.
1033 */
1034 if (unlikely(dl_task(curr)) &&
1035 (tsk_nr_cpus_allowed(curr) < 2 ||
1036 !dl_entity_preempt(&p->dl, &curr->dl)) &&
1037 (tsk_nr_cpus_allowed(p) > 1)) {
1038 int target = find_later_rq(p);
1039
1040 if (target != -1 &&
1041 (dl_time_before(p->dl.deadline,
1042 cpu_rq(target)->dl.earliest_dl.curr) ||
1043 (cpu_rq(target)->dl.dl_nr_running == 0)))
1044 cpu = target;
1045 }
1046 rcu_read_unlock();
1047
1048out:
1049 return cpu;
1050}
1051
1052static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
1053{
1054 /*
1055 * Current can't be migrated, useless to reschedule,
1056 * let's hope p can move out.
1057 */
1058 if (tsk_nr_cpus_allowed(rq->curr) == 1 ||
1059 cpudl_find(&rq->rd->cpudl, rq->curr, NULL) == -1)
1060 return;
1061
1062 /*
1063 * p is migratable, so let's not schedule it and
1064 * see if it is pushed or pulled somewhere else.
1065 */
1066 if (tsk_nr_cpus_allowed(p) != 1 &&
1067 cpudl_find(&rq->rd->cpudl, p, NULL) != -1)
1068 return;
1069
1070 resched_curr(rq);
1071}
1072
1073#endif /* CONFIG_SMP */
1074
1075/*
1076 * Only called when both the current and waking task are -deadline
1077 * tasks.
1078 */
1079static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
1080 int flags)
1081{
1082 if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
1083 resched_curr(rq);
1084 return;
1085 }
1086
1087#ifdef CONFIG_SMP
1088 /*
1089 * In the unlikely case current and p have the same deadline
1090 * let us try to decide what's the best thing to do...
1091 */
1092 if ((p->dl.deadline == rq->curr->dl.deadline) &&
1093 !test_tsk_need_resched(rq->curr))
1094 check_preempt_equal_dl(rq, p);
1095#endif /* CONFIG_SMP */
1096}
1097
1098#ifdef CONFIG_SCHED_HRTICK
1099static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1100{
1101 hrtick_start(rq, p->dl.runtime);
1102}
1103#else /* !CONFIG_SCHED_HRTICK */
1104static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1105{
1106}
1107#endif
1108
1109static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
1110 struct dl_rq *dl_rq)
1111{
1112 struct rb_node *left = dl_rq->rb_leftmost;
1113
1114 if (!left)
1115 return NULL;
1116
1117 return rb_entry(left, struct sched_dl_entity, rb_node);
1118}
1119
1120struct task_struct *
1121pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct pin_cookie cookie)
1122{
1123 struct sched_dl_entity *dl_se;
1124 struct task_struct *p;
1125 struct dl_rq *dl_rq;
1126
1127 dl_rq = &rq->dl;
1128
1129 if (need_pull_dl_task(rq, prev)) {
1130 /*
1131 * This is OK, because current is on_cpu, which avoids it being
1132 * picked for load-balance and preemption/IRQs are still
1133 * disabled avoiding further scheduler activity on it and we're
1134 * being very careful to re-start the picking loop.
1135 */
1136 lockdep_unpin_lock(&rq->lock, cookie);
1137 pull_dl_task(rq);
1138 lockdep_repin_lock(&rq->lock, cookie);
1139 /*
1140 * pull_dl_task() can drop (and re-acquire) rq->lock; this
1141 * means a stop task can slip in, in which case we need to
1142 * re-start task selection.
1143 */
1144 if (rq->stop && task_on_rq_queued(rq->stop))
1145 return RETRY_TASK;
1146 }
1147
1148 /*
1149 * When prev is DL, we may throttle it in put_prev_task().
1150 * So, we update time before we check for dl_nr_running.
1151 */
1152 if (prev->sched_class == &dl_sched_class)
1153 update_curr_dl(rq);
1154
1155 if (unlikely(!dl_rq->dl_nr_running))
1156 return NULL;
1157
1158 put_prev_task(rq, prev);
1159
1160 dl_se = pick_next_dl_entity(rq, dl_rq);
1161 BUG_ON(!dl_se);
1162
1163 p = dl_task_of(dl_se);
1164 p->se.exec_start = rq_clock_task(rq);
1165
1166 /* Running task will never be pushed. */
1167 dequeue_pushable_dl_task(rq, p);
1168
1169 if (hrtick_enabled(rq))
1170 start_hrtick_dl(rq, p);
1171
1172 queue_push_tasks(rq);
1173
1174 return p;
1175}
1176
1177static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
1178{
1179 update_curr_dl(rq);
1180
1181 if (on_dl_rq(&p->dl) && tsk_nr_cpus_allowed(p) > 1)
1182 enqueue_pushable_dl_task(rq, p);
1183}
1184
1185static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
1186{
1187 update_curr_dl(rq);
1188
1189 /*
1190 * Even when we have runtime, update_curr_dl() might have resulted in us
1191 * not being the leftmost task anymore. In that case NEED_RESCHED will
1192 * be set and schedule() will start a new hrtick for the next task.
1193 */
1194 if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 &&
1195 is_leftmost(p, &rq->dl))
1196 start_hrtick_dl(rq, p);
1197}
1198
1199static void task_fork_dl(struct task_struct *p)
1200{
1201 /*
1202 * SCHED_DEADLINE tasks cannot fork and this is achieved through
1203 * sched_fork()
1204 */
1205}
1206
1207static void task_dead_dl(struct task_struct *p)
1208{
1209 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
1210
1211 /*
1212 * Since we are TASK_DEAD we won't slip out of the domain!
1213 */
1214 raw_spin_lock_irq(&dl_b->lock);
1215 /* XXX we should retain the bw until 0-lag */
1216 dl_b->total_bw -= p->dl.dl_bw;
1217 raw_spin_unlock_irq(&dl_b->lock);
1218}
1219
1220static void set_curr_task_dl(struct rq *rq)
1221{
1222 struct task_struct *p = rq->curr;
1223
1224 p->se.exec_start = rq_clock_task(rq);
1225
1226 /* You can't push away the running task */
1227 dequeue_pushable_dl_task(rq, p);
1228}
1229
1230#ifdef CONFIG_SMP
1231
1232/* Only try algorithms three times */
1233#define DL_MAX_TRIES 3
1234
1235static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
1236{
1237 if (!task_running(rq, p) &&
1238 cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
1239 return 1;
1240 return 0;
1241}
1242
1243/*
1244 * Return the earliest pushable rq's task, which is suitable to be executed
1245 * on the CPU, NULL otherwise:
1246 */
1247static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu)
1248{
1249 struct rb_node *next_node = rq->dl.pushable_dl_tasks_leftmost;
1250 struct task_struct *p = NULL;
1251
1252 if (!has_pushable_dl_tasks(rq))
1253 return NULL;
1254
1255next_node:
1256 if (next_node) {
1257 p = rb_entry(next_node, struct task_struct, pushable_dl_tasks);
1258
1259 if (pick_dl_task(rq, p, cpu))
1260 return p;
1261
1262 next_node = rb_next(next_node);
1263 goto next_node;
1264 }
1265
1266 return NULL;
1267}
1268
1269static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
1270
1271static int find_later_rq(struct task_struct *task)
1272{
1273 struct sched_domain *sd;
1274 struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl);
1275 int this_cpu = smp_processor_id();
1276 int best_cpu, cpu = task_cpu(task);
1277
1278 /* Make sure the mask is initialized first */
1279 if (unlikely(!later_mask))
1280 return -1;
1281
1282 if (tsk_nr_cpus_allowed(task) == 1)
1283 return -1;
1284
1285 /*
1286 * We have to consider system topology and task affinity
1287 * first, then we can look for a suitable cpu.
1288 */
1289 best_cpu = cpudl_find(&task_rq(task)->rd->cpudl,
1290 task, later_mask);
1291 if (best_cpu == -1)
1292 return -1;
1293
1294 /*
1295 * If we are here, some target has been found,
1296 * the most suitable of which is cached in best_cpu.
1297 * This is, among the runqueues where the current tasks
1298 * have later deadlines than the task's one, the rq
1299 * with the latest possible one.
1300 *
1301 * Now we check how well this matches with task's
1302 * affinity and system topology.
1303 *
1304 * The last cpu where the task run is our first
1305 * guess, since it is most likely cache-hot there.
1306 */
1307 if (cpumask_test_cpu(cpu, later_mask))
1308 return cpu;
1309 /*
1310 * Check if this_cpu is to be skipped (i.e., it is
1311 * not in the mask) or not.
1312 */
1313 if (!cpumask_test_cpu(this_cpu, later_mask))
1314 this_cpu = -1;
1315
1316 rcu_read_lock();
1317 for_each_domain(cpu, sd) {
1318 if (sd->flags & SD_WAKE_AFFINE) {
1319
1320 /*
1321 * If possible, preempting this_cpu is
1322 * cheaper than migrating.
1323 */
1324 if (this_cpu != -1 &&
1325 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1326 rcu_read_unlock();
1327 return this_cpu;
1328 }
1329
1330 /*
1331 * Last chance: if best_cpu is valid and is
1332 * in the mask, that becomes our choice.
1333 */
1334 if (best_cpu < nr_cpu_ids &&
1335 cpumask_test_cpu(best_cpu, sched_domain_span(sd))) {
1336 rcu_read_unlock();
1337 return best_cpu;
1338 }
1339 }
1340 }
1341 rcu_read_unlock();
1342
1343 /*
1344 * At this point, all our guesses failed, we just return
1345 * 'something', and let the caller sort the things out.
1346 */
1347 if (this_cpu != -1)
1348 return this_cpu;
1349
1350 cpu = cpumask_any(later_mask);
1351 if (cpu < nr_cpu_ids)
1352 return cpu;
1353
1354 return -1;
1355}
1356
1357/* Locks the rq it finds */
1358static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
1359{
1360 struct rq *later_rq = NULL;
1361 int tries;
1362 int cpu;
1363
1364 for (tries = 0; tries < DL_MAX_TRIES; tries++) {
1365 cpu = find_later_rq(task);
1366
1367 if ((cpu == -1) || (cpu == rq->cpu))
1368 break;
1369
1370 later_rq = cpu_rq(cpu);
1371
1372 if (later_rq->dl.dl_nr_running &&
1373 !dl_time_before(task->dl.deadline,
1374 later_rq->dl.earliest_dl.curr)) {
1375 /*
1376 * Target rq has tasks of equal or earlier deadline,
1377 * retrying does not release any lock and is unlikely
1378 * to yield a different result.
1379 */
1380 later_rq = NULL;
1381 break;
1382 }
1383
1384 /* Retry if something changed. */
1385 if (double_lock_balance(rq, later_rq)) {
1386 if (unlikely(task_rq(task) != rq ||
1387 !cpumask_test_cpu(later_rq->cpu,
1388 tsk_cpus_allowed(task)) ||
1389 task_running(rq, task) ||
1390 !dl_task(task) ||
1391 !task_on_rq_queued(task))) {
1392 double_unlock_balance(rq, later_rq);
1393 later_rq = NULL;
1394 break;
1395 }
1396 }
1397
1398 /*
1399 * If the rq we found has no -deadline task, or
1400 * its earliest one has a later deadline than our
1401 * task, the rq is a good one.
1402 */
1403 if (!later_rq->dl.dl_nr_running ||
1404 dl_time_before(task->dl.deadline,
1405 later_rq->dl.earliest_dl.curr))
1406 break;
1407
1408 /* Otherwise we try again. */
1409 double_unlock_balance(rq, later_rq);
1410 later_rq = NULL;
1411 }
1412
1413 return later_rq;
1414}
1415
1416static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
1417{
1418 struct task_struct *p;
1419
1420 if (!has_pushable_dl_tasks(rq))
1421 return NULL;
1422
1423 p = rb_entry(rq->dl.pushable_dl_tasks_leftmost,
1424 struct task_struct, pushable_dl_tasks);
1425
1426 BUG_ON(rq->cpu != task_cpu(p));
1427 BUG_ON(task_current(rq, p));
1428 BUG_ON(tsk_nr_cpus_allowed(p) <= 1);
1429
1430 BUG_ON(!task_on_rq_queued(p));
1431 BUG_ON(!dl_task(p));
1432
1433 return p;
1434}
1435
1436/*
1437 * See if the non running -deadline tasks on this rq
1438 * can be sent to some other CPU where they can preempt
1439 * and start executing.
1440 */
1441static int push_dl_task(struct rq *rq)
1442{
1443 struct task_struct *next_task;
1444 struct rq *later_rq;
1445 int ret = 0;
1446
1447 if (!rq->dl.overloaded)
1448 return 0;
1449
1450 next_task = pick_next_pushable_dl_task(rq);
1451 if (!next_task)
1452 return 0;
1453
1454retry:
1455 if (unlikely(next_task == rq->curr)) {
1456 WARN_ON(1);
1457 return 0;
1458 }
1459
1460 /*
1461 * If next_task preempts rq->curr, and rq->curr
1462 * can move away, it makes sense to just reschedule
1463 * without going further in pushing next_task.
1464 */
1465 if (dl_task(rq->curr) &&
1466 dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
1467 tsk_nr_cpus_allowed(rq->curr) > 1) {
1468 resched_curr(rq);
1469 return 0;
1470 }
1471
1472 /* We might release rq lock */
1473 get_task_struct(next_task);
1474
1475 /* Will lock the rq it'll find */
1476 later_rq = find_lock_later_rq(next_task, rq);
1477 if (!later_rq) {
1478 struct task_struct *task;
1479
1480 /*
1481 * We must check all this again, since
1482 * find_lock_later_rq releases rq->lock and it is
1483 * then possible that next_task has migrated.
1484 */
1485 task = pick_next_pushable_dl_task(rq);
1486 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1487 /*
1488 * The task is still there. We don't try
1489 * again, some other cpu will pull it when ready.
1490 */
1491 goto out;
1492 }
1493
1494 if (!task)
1495 /* No more tasks */
1496 goto out;
1497
1498 put_task_struct(next_task);
1499 next_task = task;
1500 goto retry;
1501 }
1502
1503 deactivate_task(rq, next_task, 0);
1504 set_task_cpu(next_task, later_rq->cpu);
1505 activate_task(later_rq, next_task, 0);
1506 ret = 1;
1507
1508 resched_curr(later_rq);
1509
1510 double_unlock_balance(rq, later_rq);
1511
1512out:
1513 put_task_struct(next_task);
1514
1515 return ret;
1516}
1517
1518static void push_dl_tasks(struct rq *rq)
1519{
1520 /* push_dl_task() will return true if it moved a -deadline task */
1521 while (push_dl_task(rq))
1522 ;
1523}
1524
1525static void pull_dl_task(struct rq *this_rq)
1526{
1527 int this_cpu = this_rq->cpu, cpu;
1528 struct task_struct *p;
1529 bool resched = false;
1530 struct rq *src_rq;
1531 u64 dmin = LONG_MAX;
1532
1533 if (likely(!dl_overloaded(this_rq)))
1534 return;
1535
1536 /*
1537 * Match the barrier from dl_set_overloaded; this guarantees that if we
1538 * see overloaded we must also see the dlo_mask bit.
1539 */
1540 smp_rmb();
1541
1542 for_each_cpu(cpu, this_rq->rd->dlo_mask) {
1543 if (this_cpu == cpu)
1544 continue;
1545
1546 src_rq = cpu_rq(cpu);
1547
1548 /*
1549 * It looks racy, abd it is! However, as in sched_rt.c,
1550 * we are fine with this.
1551 */
1552 if (this_rq->dl.dl_nr_running &&
1553 dl_time_before(this_rq->dl.earliest_dl.curr,
1554 src_rq->dl.earliest_dl.next))
1555 continue;
1556
1557 /* Might drop this_rq->lock */
1558 double_lock_balance(this_rq, src_rq);
1559
1560 /*
1561 * If there are no more pullable tasks on the
1562 * rq, we're done with it.
1563 */
1564 if (src_rq->dl.dl_nr_running <= 1)
1565 goto skip;
1566
1567 p = pick_earliest_pushable_dl_task(src_rq, this_cpu);
1568
1569 /*
1570 * We found a task to be pulled if:
1571 * - it preempts our current (if there's one),
1572 * - it will preempt the last one we pulled (if any).
1573 */
1574 if (p && dl_time_before(p->dl.deadline, dmin) &&
1575 (!this_rq->dl.dl_nr_running ||
1576 dl_time_before(p->dl.deadline,
1577 this_rq->dl.earliest_dl.curr))) {
1578 WARN_ON(p == src_rq->curr);
1579 WARN_ON(!task_on_rq_queued(p));
1580
1581 /*
1582 * Then we pull iff p has actually an earlier
1583 * deadline than the current task of its runqueue.
1584 */
1585 if (dl_time_before(p->dl.deadline,
1586 src_rq->curr->dl.deadline))
1587 goto skip;
1588
1589 resched = true;
1590
1591 deactivate_task(src_rq, p, 0);
1592 set_task_cpu(p, this_cpu);
1593 activate_task(this_rq, p, 0);
1594 dmin = p->dl.deadline;
1595
1596 /* Is there any other task even earlier? */
1597 }
1598skip:
1599 double_unlock_balance(this_rq, src_rq);
1600 }
1601
1602 if (resched)
1603 resched_curr(this_rq);
1604}
1605
1606/*
1607 * Since the task is not running and a reschedule is not going to happen
1608 * anytime soon on its runqueue, we try pushing it away now.
1609 */
1610static void task_woken_dl(struct rq *rq, struct task_struct *p)
1611{
1612 if (!task_running(rq, p) &&
1613 !test_tsk_need_resched(rq->curr) &&
1614 tsk_nr_cpus_allowed(p) > 1 &&
1615 dl_task(rq->curr) &&
1616 (tsk_nr_cpus_allowed(rq->curr) < 2 ||
1617 !dl_entity_preempt(&p->dl, &rq->curr->dl))) {
1618 push_dl_tasks(rq);
1619 }
1620}
1621
1622static void set_cpus_allowed_dl(struct task_struct *p,
1623 const struct cpumask *new_mask)
1624{
1625 struct root_domain *src_rd;
1626 struct rq *rq;
1627
1628 BUG_ON(!dl_task(p));
1629
1630 rq = task_rq(p);
1631 src_rd = rq->rd;
1632 /*
1633 * Migrating a SCHED_DEADLINE task between exclusive
1634 * cpusets (different root_domains) entails a bandwidth
1635 * update. We already made space for us in the destination
1636 * domain (see cpuset_can_attach()).
1637 */
1638 if (!cpumask_intersects(src_rd->span, new_mask)) {
1639 struct dl_bw *src_dl_b;
1640
1641 src_dl_b = dl_bw_of(cpu_of(rq));
1642 /*
1643 * We now free resources of the root_domain we are migrating
1644 * off. In the worst case, sched_setattr() may temporary fail
1645 * until we complete the update.
1646 */
1647 raw_spin_lock(&src_dl_b->lock);
1648 __dl_clear(src_dl_b, p->dl.dl_bw);
1649 raw_spin_unlock(&src_dl_b->lock);
1650 }
1651
1652 set_cpus_allowed_common(p, new_mask);
1653}
1654
1655/* Assumes rq->lock is held */
1656static void rq_online_dl(struct rq *rq)
1657{
1658 if (rq->dl.overloaded)
1659 dl_set_overload(rq);
1660
1661 cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
1662 if (rq->dl.dl_nr_running > 0)
1663 cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr);
1664}
1665
1666/* Assumes rq->lock is held */
1667static void rq_offline_dl(struct rq *rq)
1668{
1669 if (rq->dl.overloaded)
1670 dl_clear_overload(rq);
1671
1672 cpudl_clear(&rq->rd->cpudl, rq->cpu);
1673 cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
1674}
1675
1676void __init init_sched_dl_class(void)
1677{
1678 unsigned int i;
1679
1680 for_each_possible_cpu(i)
1681 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
1682 GFP_KERNEL, cpu_to_node(i));
1683}
1684
1685#endif /* CONFIG_SMP */
1686
1687static void switched_from_dl(struct rq *rq, struct task_struct *p)
1688{
1689 /*
1690 * Start the deadline timer; if we switch back to dl before this we'll
1691 * continue consuming our current CBS slice. If we stay outside of
1692 * SCHED_DEADLINE until the deadline passes, the timer will reset the
1693 * task.
1694 */
1695 if (!start_dl_timer(p))
1696 __dl_clear_params(p);
1697
1698 /*
1699 * Since this might be the only -deadline task on the rq,
1700 * this is the right place to try to pull some other one
1701 * from an overloaded cpu, if any.
1702 */
1703 if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
1704 return;
1705
1706 queue_pull_task(rq);
1707}
1708
1709/*
1710 * When switching to -deadline, we may overload the rq, then
1711 * we try to push someone off, if possible.
1712 */
1713static void switched_to_dl(struct rq *rq, struct task_struct *p)
1714{
1715
1716 /* If p is not queued we will update its parameters at next wakeup. */
1717 if (!task_on_rq_queued(p))
1718 return;
1719
1720 /*
1721 * If p is boosted we already updated its params in
1722 * rt_mutex_setprio()->enqueue_task(..., ENQUEUE_REPLENISH),
1723 * p's deadline being now already after rq_clock(rq).
1724 */
1725 if (dl_time_before(p->dl.deadline, rq_clock(rq)))
1726 setup_new_dl_entity(&p->dl);
1727
1728 if (rq->curr != p) {
1729#ifdef CONFIG_SMP
1730 if (tsk_nr_cpus_allowed(p) > 1 && rq->dl.overloaded)
1731 queue_push_tasks(rq);
1732#endif
1733 if (dl_task(rq->curr))
1734 check_preempt_curr_dl(rq, p, 0);
1735 else
1736 resched_curr(rq);
1737 }
1738}
1739
1740/*
1741 * If the scheduling parameters of a -deadline task changed,
1742 * a push or pull operation might be needed.
1743 */
1744static void prio_changed_dl(struct rq *rq, struct task_struct *p,
1745 int oldprio)
1746{
1747 if (task_on_rq_queued(p) || rq->curr == p) {
1748#ifdef CONFIG_SMP
1749 /*
1750 * This might be too much, but unfortunately
1751 * we don't have the old deadline value, and
1752 * we can't argue if the task is increasing
1753 * or lowering its prio, so...
1754 */
1755 if (!rq->dl.overloaded)
1756 queue_pull_task(rq);
1757
1758 /*
1759 * If we now have a earlier deadline task than p,
1760 * then reschedule, provided p is still on this
1761 * runqueue.
1762 */
1763 if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline))
1764 resched_curr(rq);
1765#else
1766 /*
1767 * Again, we don't know if p has a earlier
1768 * or later deadline, so let's blindly set a
1769 * (maybe not needed) rescheduling point.
1770 */
1771 resched_curr(rq);
1772#endif /* CONFIG_SMP */
1773 }
1774}
1775
1776const struct sched_class dl_sched_class = {
1777 .next = &rt_sched_class,
1778 .enqueue_task = enqueue_task_dl,
1779 .dequeue_task = dequeue_task_dl,
1780 .yield_task = yield_task_dl,
1781
1782 .check_preempt_curr = check_preempt_curr_dl,
1783
1784 .pick_next_task = pick_next_task_dl,
1785 .put_prev_task = put_prev_task_dl,
1786
1787#ifdef CONFIG_SMP
1788 .select_task_rq = select_task_rq_dl,
1789 .set_cpus_allowed = set_cpus_allowed_dl,
1790 .rq_online = rq_online_dl,
1791 .rq_offline = rq_offline_dl,
1792 .task_woken = task_woken_dl,
1793#endif
1794
1795 .set_curr_task = set_curr_task_dl,
1796 .task_tick = task_tick_dl,
1797 .task_fork = task_fork_dl,
1798 .task_dead = task_dead_dl,
1799
1800 .prio_changed = prio_changed_dl,
1801 .switched_from = switched_from_dl,
1802 .switched_to = switched_to_dl,
1803
1804 .update_curr = update_curr_dl,
1805};
1806
1807#ifdef CONFIG_SCHED_DEBUG
1808extern void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq);
1809
1810void print_dl_stats(struct seq_file *m, int cpu)
1811{
1812 print_dl_rq(m, cpu, &cpu_rq(cpu)->dl);
1813}
1814#endif /* CONFIG_SCHED_DEBUG */
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Deadline Scheduling Class (SCHED_DEADLINE)
4 *
5 * Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS).
6 *
7 * Tasks that periodically executes their instances for less than their
8 * runtime won't miss any of their deadlines.
9 * Tasks that are not periodic or sporadic or that tries to execute more
10 * than their reserved bandwidth will be slowed down (and may potentially
11 * miss some of their deadlines), and won't affect any other task.
12 *
13 * Copyright (C) 2012 Dario Faggioli <raistlin@linux.it>,
14 * Juri Lelli <juri.lelli@gmail.com>,
15 * Michael Trimarchi <michael@amarulasolutions.com>,
16 * Fabio Checconi <fchecconi@gmail.com>
17 */
18
19#include <linux/cpuset.h>
20
21/*
22 * Default limits for DL period; on the top end we guard against small util
23 * tasks still getting ridiculously long effective runtimes, on the bottom end we
24 * guard against timer DoS.
25 */
26static unsigned int sysctl_sched_dl_period_max = 1 << 22; /* ~4 seconds */
27static unsigned int sysctl_sched_dl_period_min = 100; /* 100 us */
28#ifdef CONFIG_SYSCTL
29static struct ctl_table sched_dl_sysctls[] = {
30 {
31 .procname = "sched_deadline_period_max_us",
32 .data = &sysctl_sched_dl_period_max,
33 .maxlen = sizeof(unsigned int),
34 .mode = 0644,
35 .proc_handler = proc_douintvec_minmax,
36 .extra1 = (void *)&sysctl_sched_dl_period_min,
37 },
38 {
39 .procname = "sched_deadline_period_min_us",
40 .data = &sysctl_sched_dl_period_min,
41 .maxlen = sizeof(unsigned int),
42 .mode = 0644,
43 .proc_handler = proc_douintvec_minmax,
44 .extra2 = (void *)&sysctl_sched_dl_period_max,
45 },
46 {}
47};
48
49static int __init sched_dl_sysctl_init(void)
50{
51 register_sysctl_init("kernel", sched_dl_sysctls);
52 return 0;
53}
54late_initcall(sched_dl_sysctl_init);
55#endif
56
57static bool dl_server(struct sched_dl_entity *dl_se)
58{
59 return dl_se->dl_server;
60}
61
62static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
63{
64 BUG_ON(dl_server(dl_se));
65 return container_of(dl_se, struct task_struct, dl);
66}
67
68static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq)
69{
70 return container_of(dl_rq, struct rq, dl);
71}
72
73static inline struct rq *rq_of_dl_se(struct sched_dl_entity *dl_se)
74{
75 struct rq *rq = dl_se->rq;
76
77 if (!dl_server(dl_se))
78 rq = task_rq(dl_task_of(dl_se));
79
80 return rq;
81}
82
83static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se)
84{
85 return &rq_of_dl_se(dl_se)->dl;
86}
87
88static inline int on_dl_rq(struct sched_dl_entity *dl_se)
89{
90 return !RB_EMPTY_NODE(&dl_se->rb_node);
91}
92
93#ifdef CONFIG_RT_MUTEXES
94static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se)
95{
96 return dl_se->pi_se;
97}
98
99static inline bool is_dl_boosted(struct sched_dl_entity *dl_se)
100{
101 return pi_of(dl_se) != dl_se;
102}
103#else
104static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se)
105{
106 return dl_se;
107}
108
109static inline bool is_dl_boosted(struct sched_dl_entity *dl_se)
110{
111 return false;
112}
113#endif
114
115#ifdef CONFIG_SMP
116static inline struct dl_bw *dl_bw_of(int i)
117{
118 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
119 "sched RCU must be held");
120 return &cpu_rq(i)->rd->dl_bw;
121}
122
123static inline int dl_bw_cpus(int i)
124{
125 struct root_domain *rd = cpu_rq(i)->rd;
126 int cpus;
127
128 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
129 "sched RCU must be held");
130
131 if (cpumask_subset(rd->span, cpu_active_mask))
132 return cpumask_weight(rd->span);
133
134 cpus = 0;
135
136 for_each_cpu_and(i, rd->span, cpu_active_mask)
137 cpus++;
138
139 return cpus;
140}
141
142static inline unsigned long __dl_bw_capacity(const struct cpumask *mask)
143{
144 unsigned long cap = 0;
145 int i;
146
147 for_each_cpu_and(i, mask, cpu_active_mask)
148 cap += arch_scale_cpu_capacity(i);
149
150 return cap;
151}
152
153/*
154 * XXX Fix: If 'rq->rd == def_root_domain' perform AC against capacity
155 * of the CPU the task is running on rather rd's \Sum CPU capacity.
156 */
157static inline unsigned long dl_bw_capacity(int i)
158{
159 if (!sched_asym_cpucap_active() &&
160 arch_scale_cpu_capacity(i) == SCHED_CAPACITY_SCALE) {
161 return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT;
162 } else {
163 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
164 "sched RCU must be held");
165
166 return __dl_bw_capacity(cpu_rq(i)->rd->span);
167 }
168}
169
170static inline bool dl_bw_visited(int cpu, u64 gen)
171{
172 struct root_domain *rd = cpu_rq(cpu)->rd;
173
174 if (rd->visit_gen == gen)
175 return true;
176
177 rd->visit_gen = gen;
178 return false;
179}
180
181static inline
182void __dl_update(struct dl_bw *dl_b, s64 bw)
183{
184 struct root_domain *rd = container_of(dl_b, struct root_domain, dl_bw);
185 int i;
186
187 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
188 "sched RCU must be held");
189 for_each_cpu_and(i, rd->span, cpu_active_mask) {
190 struct rq *rq = cpu_rq(i);
191
192 rq->dl.extra_bw += bw;
193 }
194}
195#else
196static inline struct dl_bw *dl_bw_of(int i)
197{
198 return &cpu_rq(i)->dl.dl_bw;
199}
200
201static inline int dl_bw_cpus(int i)
202{
203 return 1;
204}
205
206static inline unsigned long dl_bw_capacity(int i)
207{
208 return SCHED_CAPACITY_SCALE;
209}
210
211static inline bool dl_bw_visited(int cpu, u64 gen)
212{
213 return false;
214}
215
216static inline
217void __dl_update(struct dl_bw *dl_b, s64 bw)
218{
219 struct dl_rq *dl = container_of(dl_b, struct dl_rq, dl_bw);
220
221 dl->extra_bw += bw;
222}
223#endif
224
225static inline
226void __dl_sub(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
227{
228 dl_b->total_bw -= tsk_bw;
229 __dl_update(dl_b, (s32)tsk_bw / cpus);
230}
231
232static inline
233void __dl_add(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
234{
235 dl_b->total_bw += tsk_bw;
236 __dl_update(dl_b, -((s32)tsk_bw / cpus));
237}
238
239static inline bool
240__dl_overflow(struct dl_bw *dl_b, unsigned long cap, u64 old_bw, u64 new_bw)
241{
242 return dl_b->bw != -1 &&
243 cap_scale(dl_b->bw, cap) < dl_b->total_bw - old_bw + new_bw;
244}
245
246static inline
247void __add_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
248{
249 u64 old = dl_rq->running_bw;
250
251 lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
252 dl_rq->running_bw += dl_bw;
253 SCHED_WARN_ON(dl_rq->running_bw < old); /* overflow */
254 SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
255 /* kick cpufreq (see the comment in kernel/sched/sched.h). */
256 cpufreq_update_util(rq_of_dl_rq(dl_rq), 0);
257}
258
259static inline
260void __sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
261{
262 u64 old = dl_rq->running_bw;
263
264 lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
265 dl_rq->running_bw -= dl_bw;
266 SCHED_WARN_ON(dl_rq->running_bw > old); /* underflow */
267 if (dl_rq->running_bw > old)
268 dl_rq->running_bw = 0;
269 /* kick cpufreq (see the comment in kernel/sched/sched.h). */
270 cpufreq_update_util(rq_of_dl_rq(dl_rq), 0);
271}
272
273static inline
274void __add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
275{
276 u64 old = dl_rq->this_bw;
277
278 lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
279 dl_rq->this_bw += dl_bw;
280 SCHED_WARN_ON(dl_rq->this_bw < old); /* overflow */
281}
282
283static inline
284void __sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
285{
286 u64 old = dl_rq->this_bw;
287
288 lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
289 dl_rq->this_bw -= dl_bw;
290 SCHED_WARN_ON(dl_rq->this_bw > old); /* underflow */
291 if (dl_rq->this_bw > old)
292 dl_rq->this_bw = 0;
293 SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
294}
295
296static inline
297void add_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
298{
299 if (!dl_entity_is_special(dl_se))
300 __add_rq_bw(dl_se->dl_bw, dl_rq);
301}
302
303static inline
304void sub_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
305{
306 if (!dl_entity_is_special(dl_se))
307 __sub_rq_bw(dl_se->dl_bw, dl_rq);
308}
309
310static inline
311void add_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
312{
313 if (!dl_entity_is_special(dl_se))
314 __add_running_bw(dl_se->dl_bw, dl_rq);
315}
316
317static inline
318void sub_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
319{
320 if (!dl_entity_is_special(dl_se))
321 __sub_running_bw(dl_se->dl_bw, dl_rq);
322}
323
324static void dl_change_utilization(struct task_struct *p, u64 new_bw)
325{
326 struct rq *rq;
327
328 WARN_ON_ONCE(p->dl.flags & SCHED_FLAG_SUGOV);
329
330 if (task_on_rq_queued(p))
331 return;
332
333 rq = task_rq(p);
334 if (p->dl.dl_non_contending) {
335 sub_running_bw(&p->dl, &rq->dl);
336 p->dl.dl_non_contending = 0;
337 /*
338 * If the timer handler is currently running and the
339 * timer cannot be canceled, inactive_task_timer()
340 * will see that dl_not_contending is not set, and
341 * will not touch the rq's active utilization,
342 * so we are still safe.
343 */
344 if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
345 put_task_struct(p);
346 }
347 __sub_rq_bw(p->dl.dl_bw, &rq->dl);
348 __add_rq_bw(new_bw, &rq->dl);
349}
350
351static void __dl_clear_params(struct sched_dl_entity *dl_se);
352
353/*
354 * The utilization of a task cannot be immediately removed from
355 * the rq active utilization (running_bw) when the task blocks.
356 * Instead, we have to wait for the so called "0-lag time".
357 *
358 * If a task blocks before the "0-lag time", a timer (the inactive
359 * timer) is armed, and running_bw is decreased when the timer
360 * fires.
361 *
362 * If the task wakes up again before the inactive timer fires,
363 * the timer is canceled, whereas if the task wakes up after the
364 * inactive timer fired (and running_bw has been decreased) the
365 * task's utilization has to be added to running_bw again.
366 * A flag in the deadline scheduling entity (dl_non_contending)
367 * is used to avoid race conditions between the inactive timer handler
368 * and task wakeups.
369 *
370 * The following diagram shows how running_bw is updated. A task is
371 * "ACTIVE" when its utilization contributes to running_bw; an
372 * "ACTIVE contending" task is in the TASK_RUNNING state, while an
373 * "ACTIVE non contending" task is a blocked task for which the "0-lag time"
374 * has not passed yet. An "INACTIVE" task is a task for which the "0-lag"
375 * time already passed, which does not contribute to running_bw anymore.
376 * +------------------+
377 * wakeup | ACTIVE |
378 * +------------------>+ contending |
379 * | add_running_bw | |
380 * | +----+------+------+
381 * | | ^
382 * | dequeue | |
383 * +--------+-------+ | |
384 * | | t >= 0-lag | | wakeup
385 * | INACTIVE |<---------------+ |
386 * | | sub_running_bw | |
387 * +--------+-------+ | |
388 * ^ | |
389 * | t < 0-lag | |
390 * | | |
391 * | V |
392 * | +----+------+------+
393 * | sub_running_bw | ACTIVE |
394 * +-------------------+ |
395 * inactive timer | non contending |
396 * fired +------------------+
397 *
398 * The task_non_contending() function is invoked when a task
399 * blocks, and checks if the 0-lag time already passed or
400 * not (in the first case, it directly updates running_bw;
401 * in the second case, it arms the inactive timer).
402 *
403 * The task_contending() function is invoked when a task wakes
404 * up, and checks if the task is still in the "ACTIVE non contending"
405 * state or not (in the second case, it updates running_bw).
406 */
407static void task_non_contending(struct sched_dl_entity *dl_se)
408{
409 struct hrtimer *timer = &dl_se->inactive_timer;
410 struct rq *rq = rq_of_dl_se(dl_se);
411 struct dl_rq *dl_rq = &rq->dl;
412 s64 zerolag_time;
413
414 /*
415 * If this is a non-deadline task that has been boosted,
416 * do nothing
417 */
418 if (dl_se->dl_runtime == 0)
419 return;
420
421 if (dl_entity_is_special(dl_se))
422 return;
423
424 WARN_ON(dl_se->dl_non_contending);
425
426 zerolag_time = dl_se->deadline -
427 div64_long((dl_se->runtime * dl_se->dl_period),
428 dl_se->dl_runtime);
429
430 /*
431 * Using relative times instead of the absolute "0-lag time"
432 * allows to simplify the code
433 */
434 zerolag_time -= rq_clock(rq);
435
436 /*
437 * If the "0-lag time" already passed, decrease the active
438 * utilization now, instead of starting a timer
439 */
440 if ((zerolag_time < 0) || hrtimer_active(&dl_se->inactive_timer)) {
441 if (dl_server(dl_se)) {
442 sub_running_bw(dl_se, dl_rq);
443 } else {
444 struct task_struct *p = dl_task_of(dl_se);
445
446 if (dl_task(p))
447 sub_running_bw(dl_se, dl_rq);
448
449 if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
450 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
451
452 if (READ_ONCE(p->__state) == TASK_DEAD)
453 sub_rq_bw(dl_se, &rq->dl);
454 raw_spin_lock(&dl_b->lock);
455 __dl_sub(dl_b, dl_se->dl_bw, dl_bw_cpus(task_cpu(p)));
456 raw_spin_unlock(&dl_b->lock);
457 __dl_clear_params(dl_se);
458 }
459 }
460
461 return;
462 }
463
464 dl_se->dl_non_contending = 1;
465 if (!dl_server(dl_se))
466 get_task_struct(dl_task_of(dl_se));
467
468 hrtimer_start(timer, ns_to_ktime(zerolag_time), HRTIMER_MODE_REL_HARD);
469}
470
471static void task_contending(struct sched_dl_entity *dl_se, int flags)
472{
473 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
474
475 /*
476 * If this is a non-deadline task that has been boosted,
477 * do nothing
478 */
479 if (dl_se->dl_runtime == 0)
480 return;
481
482 if (flags & ENQUEUE_MIGRATED)
483 add_rq_bw(dl_se, dl_rq);
484
485 if (dl_se->dl_non_contending) {
486 dl_se->dl_non_contending = 0;
487 /*
488 * If the timer handler is currently running and the
489 * timer cannot be canceled, inactive_task_timer()
490 * will see that dl_not_contending is not set, and
491 * will not touch the rq's active utilization,
492 * so we are still safe.
493 */
494 if (hrtimer_try_to_cancel(&dl_se->inactive_timer) == 1) {
495 if (!dl_server(dl_se))
496 put_task_struct(dl_task_of(dl_se));
497 }
498 } else {
499 /*
500 * Since "dl_non_contending" is not set, the
501 * task's utilization has already been removed from
502 * active utilization (either when the task blocked,
503 * when the "inactive timer" fired).
504 * So, add it back.
505 */
506 add_running_bw(dl_se, dl_rq);
507 }
508}
509
510static inline int is_leftmost(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
511{
512 return rb_first_cached(&dl_rq->root) == &dl_se->rb_node;
513}
514
515static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq);
516
517void init_dl_bw(struct dl_bw *dl_b)
518{
519 raw_spin_lock_init(&dl_b->lock);
520 if (global_rt_runtime() == RUNTIME_INF)
521 dl_b->bw = -1;
522 else
523 dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime());
524 dl_b->total_bw = 0;
525}
526
527void init_dl_rq(struct dl_rq *dl_rq)
528{
529 dl_rq->root = RB_ROOT_CACHED;
530
531#ifdef CONFIG_SMP
532 /* zero means no -deadline tasks */
533 dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0;
534
535 dl_rq->overloaded = 0;
536 dl_rq->pushable_dl_tasks_root = RB_ROOT_CACHED;
537#else
538 init_dl_bw(&dl_rq->dl_bw);
539#endif
540
541 dl_rq->running_bw = 0;
542 dl_rq->this_bw = 0;
543 init_dl_rq_bw_ratio(dl_rq);
544}
545
546#ifdef CONFIG_SMP
547
548static inline int dl_overloaded(struct rq *rq)
549{
550 return atomic_read(&rq->rd->dlo_count);
551}
552
553static inline void dl_set_overload(struct rq *rq)
554{
555 if (!rq->online)
556 return;
557
558 cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask);
559 /*
560 * Must be visible before the overload count is
561 * set (as in sched_rt.c).
562 *
563 * Matched by the barrier in pull_dl_task().
564 */
565 smp_wmb();
566 atomic_inc(&rq->rd->dlo_count);
567}
568
569static inline void dl_clear_overload(struct rq *rq)
570{
571 if (!rq->online)
572 return;
573
574 atomic_dec(&rq->rd->dlo_count);
575 cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask);
576}
577
578#define __node_2_pdl(node) \
579 rb_entry((node), struct task_struct, pushable_dl_tasks)
580
581static inline bool __pushable_less(struct rb_node *a, const struct rb_node *b)
582{
583 return dl_entity_preempt(&__node_2_pdl(a)->dl, &__node_2_pdl(b)->dl);
584}
585
586static inline int has_pushable_dl_tasks(struct rq *rq)
587{
588 return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root.rb_root);
589}
590
591/*
592 * The list of pushable -deadline task is not a plist, like in
593 * sched_rt.c, it is an rb-tree with tasks ordered by deadline.
594 */
595static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
596{
597 struct rb_node *leftmost;
598
599 WARN_ON_ONCE(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
600
601 leftmost = rb_add_cached(&p->pushable_dl_tasks,
602 &rq->dl.pushable_dl_tasks_root,
603 __pushable_less);
604 if (leftmost)
605 rq->dl.earliest_dl.next = p->dl.deadline;
606
607 if (!rq->dl.overloaded) {
608 dl_set_overload(rq);
609 rq->dl.overloaded = 1;
610 }
611}
612
613static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
614{
615 struct dl_rq *dl_rq = &rq->dl;
616 struct rb_root_cached *root = &dl_rq->pushable_dl_tasks_root;
617 struct rb_node *leftmost;
618
619 if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
620 return;
621
622 leftmost = rb_erase_cached(&p->pushable_dl_tasks, root);
623 if (leftmost)
624 dl_rq->earliest_dl.next = __node_2_pdl(leftmost)->dl.deadline;
625
626 RB_CLEAR_NODE(&p->pushable_dl_tasks);
627
628 if (!has_pushable_dl_tasks(rq) && rq->dl.overloaded) {
629 dl_clear_overload(rq);
630 rq->dl.overloaded = 0;
631 }
632}
633
634static int push_dl_task(struct rq *rq);
635
636static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
637{
638 return rq->online && dl_task(prev);
639}
640
641static DEFINE_PER_CPU(struct balance_callback, dl_push_head);
642static DEFINE_PER_CPU(struct balance_callback, dl_pull_head);
643
644static void push_dl_tasks(struct rq *);
645static void pull_dl_task(struct rq *);
646
647static inline void deadline_queue_push_tasks(struct rq *rq)
648{
649 if (!has_pushable_dl_tasks(rq))
650 return;
651
652 queue_balance_callback(rq, &per_cpu(dl_push_head, rq->cpu), push_dl_tasks);
653}
654
655static inline void deadline_queue_pull_task(struct rq *rq)
656{
657 queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task);
658}
659
660static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq);
661
662static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p)
663{
664 struct rq *later_rq = NULL;
665 struct dl_bw *dl_b;
666
667 later_rq = find_lock_later_rq(p, rq);
668 if (!later_rq) {
669 int cpu;
670
671 /*
672 * If we cannot preempt any rq, fall back to pick any
673 * online CPU:
674 */
675 cpu = cpumask_any_and(cpu_active_mask, p->cpus_ptr);
676 if (cpu >= nr_cpu_ids) {
677 /*
678 * Failed to find any suitable CPU.
679 * The task will never come back!
680 */
681 WARN_ON_ONCE(dl_bandwidth_enabled());
682
683 /*
684 * If admission control is disabled we
685 * try a little harder to let the task
686 * run.
687 */
688 cpu = cpumask_any(cpu_active_mask);
689 }
690 later_rq = cpu_rq(cpu);
691 double_lock_balance(rq, later_rq);
692 }
693
694 if (p->dl.dl_non_contending || p->dl.dl_throttled) {
695 /*
696 * Inactive timer is armed (or callback is running, but
697 * waiting for us to release rq locks). In any case, when it
698 * will fire (or continue), it will see running_bw of this
699 * task migrated to later_rq (and correctly handle it).
700 */
701 sub_running_bw(&p->dl, &rq->dl);
702 sub_rq_bw(&p->dl, &rq->dl);
703
704 add_rq_bw(&p->dl, &later_rq->dl);
705 add_running_bw(&p->dl, &later_rq->dl);
706 } else {
707 sub_rq_bw(&p->dl, &rq->dl);
708 add_rq_bw(&p->dl, &later_rq->dl);
709 }
710
711 /*
712 * And we finally need to fixup root_domain(s) bandwidth accounting,
713 * since p is still hanging out in the old (now moved to default) root
714 * domain.
715 */
716 dl_b = &rq->rd->dl_bw;
717 raw_spin_lock(&dl_b->lock);
718 __dl_sub(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span));
719 raw_spin_unlock(&dl_b->lock);
720
721 dl_b = &later_rq->rd->dl_bw;
722 raw_spin_lock(&dl_b->lock);
723 __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(later_rq->rd->span));
724 raw_spin_unlock(&dl_b->lock);
725
726 set_task_cpu(p, later_rq->cpu);
727 double_unlock_balance(later_rq, rq);
728
729 return later_rq;
730}
731
732#else
733
734static inline
735void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
736{
737}
738
739static inline
740void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
741{
742}
743
744static inline
745void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
746{
747}
748
749static inline
750void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
751{
752}
753
754static inline void deadline_queue_push_tasks(struct rq *rq)
755{
756}
757
758static inline void deadline_queue_pull_task(struct rq *rq)
759{
760}
761#endif /* CONFIG_SMP */
762
763static void
764enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags);
765static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags);
766static void dequeue_dl_entity(struct sched_dl_entity *dl_se, int flags);
767static void wakeup_preempt_dl(struct rq *rq, struct task_struct *p, int flags);
768
769static inline void replenish_dl_new_period(struct sched_dl_entity *dl_se,
770 struct rq *rq)
771{
772 /* for non-boosted task, pi_of(dl_se) == dl_se */
773 dl_se->deadline = rq_clock(rq) + pi_of(dl_se)->dl_deadline;
774 dl_se->runtime = pi_of(dl_se)->dl_runtime;
775}
776
777/*
778 * We are being explicitly informed that a new instance is starting,
779 * and this means that:
780 * - the absolute deadline of the entity has to be placed at
781 * current time + relative deadline;
782 * - the runtime of the entity has to be set to the maximum value.
783 *
784 * The capability of specifying such event is useful whenever a -deadline
785 * entity wants to (try to!) synchronize its behaviour with the scheduler's
786 * one, and to (try to!) reconcile itself with its own scheduling
787 * parameters.
788 */
789static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se)
790{
791 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
792 struct rq *rq = rq_of_dl_rq(dl_rq);
793
794 WARN_ON(is_dl_boosted(dl_se));
795 WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline));
796
797 /*
798 * We are racing with the deadline timer. So, do nothing because
799 * the deadline timer handler will take care of properly recharging
800 * the runtime and postponing the deadline
801 */
802 if (dl_se->dl_throttled)
803 return;
804
805 /*
806 * We use the regular wall clock time to set deadlines in the
807 * future; in fact, we must consider execution overheads (time
808 * spent on hardirq context, etc.).
809 */
810 replenish_dl_new_period(dl_se, rq);
811}
812
813/*
814 * Pure Earliest Deadline First (EDF) scheduling does not deal with the
815 * possibility of a entity lasting more than what it declared, and thus
816 * exhausting its runtime.
817 *
818 * Here we are interested in making runtime overrun possible, but we do
819 * not want a entity which is misbehaving to affect the scheduling of all
820 * other entities.
821 * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
822 * is used, in order to confine each entity within its own bandwidth.
823 *
824 * This function deals exactly with that, and ensures that when the runtime
825 * of a entity is replenished, its deadline is also postponed. That ensures
826 * the overrunning entity can't interfere with other entity in the system and
827 * can't make them miss their deadlines. Reasons why this kind of overruns
828 * could happen are, typically, a entity voluntarily trying to overcome its
829 * runtime, or it just underestimated it during sched_setattr().
830 */
831static void replenish_dl_entity(struct sched_dl_entity *dl_se)
832{
833 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
834 struct rq *rq = rq_of_dl_rq(dl_rq);
835
836 WARN_ON_ONCE(pi_of(dl_se)->dl_runtime <= 0);
837
838 /*
839 * This could be the case for a !-dl task that is boosted.
840 * Just go with full inherited parameters.
841 */
842 if (dl_se->dl_deadline == 0)
843 replenish_dl_new_period(dl_se, rq);
844
845 if (dl_se->dl_yielded && dl_se->runtime > 0)
846 dl_se->runtime = 0;
847
848 /*
849 * We keep moving the deadline away until we get some
850 * available runtime for the entity. This ensures correct
851 * handling of situations where the runtime overrun is
852 * arbitrary large.
853 */
854 while (dl_se->runtime <= 0) {
855 dl_se->deadline += pi_of(dl_se)->dl_period;
856 dl_se->runtime += pi_of(dl_se)->dl_runtime;
857 }
858
859 /*
860 * At this point, the deadline really should be "in
861 * the future" with respect to rq->clock. If it's
862 * not, we are, for some reason, lagging too much!
863 * Anyway, after having warn userspace abut that,
864 * we still try to keep the things running by
865 * resetting the deadline and the budget of the
866 * entity.
867 */
868 if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
869 printk_deferred_once("sched: DL replenish lagged too much\n");
870 replenish_dl_new_period(dl_se, rq);
871 }
872
873 if (dl_se->dl_yielded)
874 dl_se->dl_yielded = 0;
875 if (dl_se->dl_throttled)
876 dl_se->dl_throttled = 0;
877}
878
879/*
880 * Here we check if --at time t-- an entity (which is probably being
881 * [re]activated or, in general, enqueued) can use its remaining runtime
882 * and its current deadline _without_ exceeding the bandwidth it is
883 * assigned (function returns true if it can't). We are in fact applying
884 * one of the CBS rules: when a task wakes up, if the residual runtime
885 * over residual deadline fits within the allocated bandwidth, then we
886 * can keep the current (absolute) deadline and residual budget without
887 * disrupting the schedulability of the system. Otherwise, we should
888 * refill the runtime and set the deadline a period in the future,
889 * because keeping the current (absolute) deadline of the task would
890 * result in breaking guarantees promised to other tasks (refer to
891 * Documentation/scheduler/sched-deadline.rst for more information).
892 *
893 * This function returns true if:
894 *
895 * runtime / (deadline - t) > dl_runtime / dl_deadline ,
896 *
897 * IOW we can't recycle current parameters.
898 *
899 * Notice that the bandwidth check is done against the deadline. For
900 * task with deadline equal to period this is the same of using
901 * dl_period instead of dl_deadline in the equation above.
902 */
903static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t)
904{
905 u64 left, right;
906
907 /*
908 * left and right are the two sides of the equation above,
909 * after a bit of shuffling to use multiplications instead
910 * of divisions.
911 *
912 * Note that none of the time values involved in the two
913 * multiplications are absolute: dl_deadline and dl_runtime
914 * are the relative deadline and the maximum runtime of each
915 * instance, runtime is the runtime left for the last instance
916 * and (deadline - t), since t is rq->clock, is the time left
917 * to the (absolute) deadline. Even if overflowing the u64 type
918 * is very unlikely to occur in both cases, here we scale down
919 * as we want to avoid that risk at all. Scaling down by 10
920 * means that we reduce granularity to 1us. We are fine with it,
921 * since this is only a true/false check and, anyway, thinking
922 * of anything below microseconds resolution is actually fiction
923 * (but still we want to give the user that illusion >;).
924 */
925 left = (pi_of(dl_se)->dl_deadline >> DL_SCALE) * (dl_se->runtime >> DL_SCALE);
926 right = ((dl_se->deadline - t) >> DL_SCALE) *
927 (pi_of(dl_se)->dl_runtime >> DL_SCALE);
928
929 return dl_time_before(right, left);
930}
931
932/*
933 * Revised wakeup rule [1]: For self-suspending tasks, rather then
934 * re-initializing task's runtime and deadline, the revised wakeup
935 * rule adjusts the task's runtime to avoid the task to overrun its
936 * density.
937 *
938 * Reasoning: a task may overrun the density if:
939 * runtime / (deadline - t) > dl_runtime / dl_deadline
940 *
941 * Therefore, runtime can be adjusted to:
942 * runtime = (dl_runtime / dl_deadline) * (deadline - t)
943 *
944 * In such way that runtime will be equal to the maximum density
945 * the task can use without breaking any rule.
946 *
947 * [1] Luca Abeni, Giuseppe Lipari, and Juri Lelli. 2015. Constant
948 * bandwidth server revisited. SIGBED Rev. 11, 4 (January 2015), 19-24.
949 */
950static void
951update_dl_revised_wakeup(struct sched_dl_entity *dl_se, struct rq *rq)
952{
953 u64 laxity = dl_se->deadline - rq_clock(rq);
954
955 /*
956 * If the task has deadline < period, and the deadline is in the past,
957 * it should already be throttled before this check.
958 *
959 * See update_dl_entity() comments for further details.
960 */
961 WARN_ON(dl_time_before(dl_se->deadline, rq_clock(rq)));
962
963 dl_se->runtime = (dl_se->dl_density * laxity) >> BW_SHIFT;
964}
965
966/*
967 * Regarding the deadline, a task with implicit deadline has a relative
968 * deadline == relative period. A task with constrained deadline has a
969 * relative deadline <= relative period.
970 *
971 * We support constrained deadline tasks. However, there are some restrictions
972 * applied only for tasks which do not have an implicit deadline. See
973 * update_dl_entity() to know more about such restrictions.
974 *
975 * The dl_is_implicit() returns true if the task has an implicit deadline.
976 */
977static inline bool dl_is_implicit(struct sched_dl_entity *dl_se)
978{
979 return dl_se->dl_deadline == dl_se->dl_period;
980}
981
982/*
983 * When a deadline entity is placed in the runqueue, its runtime and deadline
984 * might need to be updated. This is done by a CBS wake up rule. There are two
985 * different rules: 1) the original CBS; and 2) the Revisited CBS.
986 *
987 * When the task is starting a new period, the Original CBS is used. In this
988 * case, the runtime is replenished and a new absolute deadline is set.
989 *
990 * When a task is queued before the begin of the next period, using the
991 * remaining runtime and deadline could make the entity to overflow, see
992 * dl_entity_overflow() to find more about runtime overflow. When such case
993 * is detected, the runtime and deadline need to be updated.
994 *
995 * If the task has an implicit deadline, i.e., deadline == period, the Original
996 * CBS is applied. the runtime is replenished and a new absolute deadline is
997 * set, as in the previous cases.
998 *
999 * However, the Original CBS does not work properly for tasks with
1000 * deadline < period, which are said to have a constrained deadline. By
1001 * applying the Original CBS, a constrained deadline task would be able to run
1002 * runtime/deadline in a period. With deadline < period, the task would
1003 * overrun the runtime/period allowed bandwidth, breaking the admission test.
1004 *
1005 * In order to prevent this misbehave, the Revisited CBS is used for
1006 * constrained deadline tasks when a runtime overflow is detected. In the
1007 * Revisited CBS, rather than replenishing & setting a new absolute deadline,
1008 * the remaining runtime of the task is reduced to avoid runtime overflow.
1009 * Please refer to the comments update_dl_revised_wakeup() function to find
1010 * more about the Revised CBS rule.
1011 */
1012static void update_dl_entity(struct sched_dl_entity *dl_se)
1013{
1014 struct rq *rq = rq_of_dl_se(dl_se);
1015
1016 if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
1017 dl_entity_overflow(dl_se, rq_clock(rq))) {
1018
1019 if (unlikely(!dl_is_implicit(dl_se) &&
1020 !dl_time_before(dl_se->deadline, rq_clock(rq)) &&
1021 !is_dl_boosted(dl_se))) {
1022 update_dl_revised_wakeup(dl_se, rq);
1023 return;
1024 }
1025
1026 replenish_dl_new_period(dl_se, rq);
1027 }
1028}
1029
1030static inline u64 dl_next_period(struct sched_dl_entity *dl_se)
1031{
1032 return dl_se->deadline - dl_se->dl_deadline + dl_se->dl_period;
1033}
1034
1035/*
1036 * If the entity depleted all its runtime, and if we want it to sleep
1037 * while waiting for some new execution time to become available, we
1038 * set the bandwidth replenishment timer to the replenishment instant
1039 * and try to activate it.
1040 *
1041 * Notice that it is important for the caller to know if the timer
1042 * actually started or not (i.e., the replenishment instant is in
1043 * the future or in the past).
1044 */
1045static int start_dl_timer(struct sched_dl_entity *dl_se)
1046{
1047 struct hrtimer *timer = &dl_se->dl_timer;
1048 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1049 struct rq *rq = rq_of_dl_rq(dl_rq);
1050 ktime_t now, act;
1051 s64 delta;
1052
1053 lockdep_assert_rq_held(rq);
1054
1055 /*
1056 * We want the timer to fire at the deadline, but considering
1057 * that it is actually coming from rq->clock and not from
1058 * hrtimer's time base reading.
1059 */
1060 act = ns_to_ktime(dl_next_period(dl_se));
1061 now = hrtimer_cb_get_time(timer);
1062 delta = ktime_to_ns(now) - rq_clock(rq);
1063 act = ktime_add_ns(act, delta);
1064
1065 /*
1066 * If the expiry time already passed, e.g., because the value
1067 * chosen as the deadline is too small, don't even try to
1068 * start the timer in the past!
1069 */
1070 if (ktime_us_delta(act, now) < 0)
1071 return 0;
1072
1073 /*
1074 * !enqueued will guarantee another callback; even if one is already in
1075 * progress. This ensures a balanced {get,put}_task_struct().
1076 *
1077 * The race against __run_timer() clearing the enqueued state is
1078 * harmless because we're holding task_rq()->lock, therefore the timer
1079 * expiring after we've done the check will wait on its task_rq_lock()
1080 * and observe our state.
1081 */
1082 if (!hrtimer_is_queued(timer)) {
1083 if (!dl_server(dl_se))
1084 get_task_struct(dl_task_of(dl_se));
1085 hrtimer_start(timer, act, HRTIMER_MODE_ABS_HARD);
1086 }
1087
1088 return 1;
1089}
1090
1091static void __push_dl_task(struct rq *rq, struct rq_flags *rf)
1092{
1093#ifdef CONFIG_SMP
1094 /*
1095 * Queueing this task back might have overloaded rq, check if we need
1096 * to kick someone away.
1097 */
1098 if (has_pushable_dl_tasks(rq)) {
1099 /*
1100 * Nothing relies on rq->lock after this, so its safe to drop
1101 * rq->lock.
1102 */
1103 rq_unpin_lock(rq, rf);
1104 push_dl_task(rq);
1105 rq_repin_lock(rq, rf);
1106 }
1107#endif
1108}
1109
1110/*
1111 * This is the bandwidth enforcement timer callback. If here, we know
1112 * a task is not on its dl_rq, since the fact that the timer was running
1113 * means the task is throttled and needs a runtime replenishment.
1114 *
1115 * However, what we actually do depends on the fact the task is active,
1116 * (it is on its rq) or has been removed from there by a call to
1117 * dequeue_task_dl(). In the former case we must issue the runtime
1118 * replenishment and add the task back to the dl_rq; in the latter, we just
1119 * do nothing but clearing dl_throttled, so that runtime and deadline
1120 * updating (and the queueing back to dl_rq) will be done by the
1121 * next call to enqueue_task_dl().
1122 */
1123static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
1124{
1125 struct sched_dl_entity *dl_se = container_of(timer,
1126 struct sched_dl_entity,
1127 dl_timer);
1128 struct task_struct *p;
1129 struct rq_flags rf;
1130 struct rq *rq;
1131
1132 if (dl_server(dl_se)) {
1133 struct rq *rq = rq_of_dl_se(dl_se);
1134 struct rq_flags rf;
1135
1136 rq_lock(rq, &rf);
1137 if (dl_se->dl_throttled) {
1138 sched_clock_tick();
1139 update_rq_clock(rq);
1140
1141 if (dl_se->server_has_tasks(dl_se)) {
1142 enqueue_dl_entity(dl_se, ENQUEUE_REPLENISH);
1143 resched_curr(rq);
1144 __push_dl_task(rq, &rf);
1145 } else {
1146 replenish_dl_entity(dl_se);
1147 }
1148
1149 }
1150 rq_unlock(rq, &rf);
1151
1152 return HRTIMER_NORESTART;
1153 }
1154
1155 p = dl_task_of(dl_se);
1156 rq = task_rq_lock(p, &rf);
1157
1158 /*
1159 * The task might have changed its scheduling policy to something
1160 * different than SCHED_DEADLINE (through switched_from_dl()).
1161 */
1162 if (!dl_task(p))
1163 goto unlock;
1164
1165 /*
1166 * The task might have been boosted by someone else and might be in the
1167 * boosting/deboosting path, its not throttled.
1168 */
1169 if (is_dl_boosted(dl_se))
1170 goto unlock;
1171
1172 /*
1173 * Spurious timer due to start_dl_timer() race; or we already received
1174 * a replenishment from rt_mutex_setprio().
1175 */
1176 if (!dl_se->dl_throttled)
1177 goto unlock;
1178
1179 sched_clock_tick();
1180 update_rq_clock(rq);
1181
1182 /*
1183 * If the throttle happened during sched-out; like:
1184 *
1185 * schedule()
1186 * deactivate_task()
1187 * dequeue_task_dl()
1188 * update_curr_dl()
1189 * start_dl_timer()
1190 * __dequeue_task_dl()
1191 * prev->on_rq = 0;
1192 *
1193 * We can be both throttled and !queued. Replenish the counter
1194 * but do not enqueue -- wait for our wakeup to do that.
1195 */
1196 if (!task_on_rq_queued(p)) {
1197 replenish_dl_entity(dl_se);
1198 goto unlock;
1199 }
1200
1201#ifdef CONFIG_SMP
1202 if (unlikely(!rq->online)) {
1203 /*
1204 * If the runqueue is no longer available, migrate the
1205 * task elsewhere. This necessarily changes rq.
1206 */
1207 lockdep_unpin_lock(__rq_lockp(rq), rf.cookie);
1208 rq = dl_task_offline_migration(rq, p);
1209 rf.cookie = lockdep_pin_lock(__rq_lockp(rq));
1210 update_rq_clock(rq);
1211
1212 /*
1213 * Now that the task has been migrated to the new RQ and we
1214 * have that locked, proceed as normal and enqueue the task
1215 * there.
1216 */
1217 }
1218#endif
1219
1220 enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
1221 if (dl_task(rq->curr))
1222 wakeup_preempt_dl(rq, p, 0);
1223 else
1224 resched_curr(rq);
1225
1226 __push_dl_task(rq, &rf);
1227
1228unlock:
1229 task_rq_unlock(rq, p, &rf);
1230
1231 /*
1232 * This can free the task_struct, including this hrtimer, do not touch
1233 * anything related to that after this.
1234 */
1235 put_task_struct(p);
1236
1237 return HRTIMER_NORESTART;
1238}
1239
1240static void init_dl_task_timer(struct sched_dl_entity *dl_se)
1241{
1242 struct hrtimer *timer = &dl_se->dl_timer;
1243
1244 hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
1245 timer->function = dl_task_timer;
1246}
1247
1248/*
1249 * During the activation, CBS checks if it can reuse the current task's
1250 * runtime and period. If the deadline of the task is in the past, CBS
1251 * cannot use the runtime, and so it replenishes the task. This rule
1252 * works fine for implicit deadline tasks (deadline == period), and the
1253 * CBS was designed for implicit deadline tasks. However, a task with
1254 * constrained deadline (deadline < period) might be awakened after the
1255 * deadline, but before the next period. In this case, replenishing the
1256 * task would allow it to run for runtime / deadline. As in this case
1257 * deadline < period, CBS enables a task to run for more than the
1258 * runtime / period. In a very loaded system, this can cause a domino
1259 * effect, making other tasks miss their deadlines.
1260 *
1261 * To avoid this problem, in the activation of a constrained deadline
1262 * task after the deadline but before the next period, throttle the
1263 * task and set the replenishing timer to the begin of the next period,
1264 * unless it is boosted.
1265 */
1266static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
1267{
1268 struct rq *rq = rq_of_dl_se(dl_se);
1269
1270 if (dl_time_before(dl_se->deadline, rq_clock(rq)) &&
1271 dl_time_before(rq_clock(rq), dl_next_period(dl_se))) {
1272 if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(dl_se)))
1273 return;
1274 dl_se->dl_throttled = 1;
1275 if (dl_se->runtime > 0)
1276 dl_se->runtime = 0;
1277 }
1278}
1279
1280static
1281int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
1282{
1283 return (dl_se->runtime <= 0);
1284}
1285
1286/*
1287 * This function implements the GRUB accounting rule. According to the
1288 * GRUB reclaiming algorithm, the runtime is not decreased as "dq = -dt",
1289 * but as "dq = -(max{u, (Umax - Uinact - Uextra)} / Umax) dt",
1290 * where u is the utilization of the task, Umax is the maximum reclaimable
1291 * utilization, Uinact is the (per-runqueue) inactive utilization, computed
1292 * as the difference between the "total runqueue utilization" and the
1293 * "runqueue active utilization", and Uextra is the (per runqueue) extra
1294 * reclaimable utilization.
1295 * Since rq->dl.running_bw and rq->dl.this_bw contain utilizations multiplied
1296 * by 2^BW_SHIFT, the result has to be shifted right by BW_SHIFT.
1297 * Since rq->dl.bw_ratio contains 1 / Umax multiplied by 2^RATIO_SHIFT, dl_bw
1298 * is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT.
1299 * Since delta is a 64 bit variable, to have an overflow its value should be
1300 * larger than 2^(64 - 20 - 8), which is more than 64 seconds. So, overflow is
1301 * not an issue here.
1302 */
1303static u64 grub_reclaim(u64 delta, struct rq *rq, struct sched_dl_entity *dl_se)
1304{
1305 u64 u_act;
1306 u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */
1307
1308 /*
1309 * Instead of computing max{u, (u_max - u_inact - u_extra)}, we
1310 * compare u_inact + u_extra with u_max - u, because u_inact + u_extra
1311 * can be larger than u_max. So, u_max - u_inact - u_extra would be
1312 * negative leading to wrong results.
1313 */
1314 if (u_inact + rq->dl.extra_bw > rq->dl.max_bw - dl_se->dl_bw)
1315 u_act = dl_se->dl_bw;
1316 else
1317 u_act = rq->dl.max_bw - u_inact - rq->dl.extra_bw;
1318
1319 u_act = (u_act * rq->dl.bw_ratio) >> RATIO_SHIFT;
1320 return (delta * u_act) >> BW_SHIFT;
1321}
1322
1323static inline void
1324update_stats_dequeue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se,
1325 int flags);
1326static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64 delta_exec)
1327{
1328 s64 scaled_delta_exec;
1329
1330 if (unlikely(delta_exec <= 0)) {
1331 if (unlikely(dl_se->dl_yielded))
1332 goto throttle;
1333 return;
1334 }
1335
1336 if (dl_entity_is_special(dl_se))
1337 return;
1338
1339 /*
1340 * For tasks that participate in GRUB, we implement GRUB-PA: the
1341 * spare reclaimed bandwidth is used to clock down frequency.
1342 *
1343 * For the others, we still need to scale reservation parameters
1344 * according to current frequency and CPU maximum capacity.
1345 */
1346 if (unlikely(dl_se->flags & SCHED_FLAG_RECLAIM)) {
1347 scaled_delta_exec = grub_reclaim(delta_exec, rq, dl_se);
1348 } else {
1349 int cpu = cpu_of(rq);
1350 unsigned long scale_freq = arch_scale_freq_capacity(cpu);
1351 unsigned long scale_cpu = arch_scale_cpu_capacity(cpu);
1352
1353 scaled_delta_exec = cap_scale(delta_exec, scale_freq);
1354 scaled_delta_exec = cap_scale(scaled_delta_exec, scale_cpu);
1355 }
1356
1357 dl_se->runtime -= scaled_delta_exec;
1358
1359throttle:
1360 if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
1361 dl_se->dl_throttled = 1;
1362
1363 /* If requested, inform the user about runtime overruns. */
1364 if (dl_runtime_exceeded(dl_se) &&
1365 (dl_se->flags & SCHED_FLAG_DL_OVERRUN))
1366 dl_se->dl_overrun = 1;
1367
1368 dequeue_dl_entity(dl_se, 0);
1369 if (!dl_server(dl_se)) {
1370 update_stats_dequeue_dl(&rq->dl, dl_se, 0);
1371 dequeue_pushable_dl_task(rq, dl_task_of(dl_se));
1372 }
1373
1374 if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(dl_se))) {
1375 if (dl_server(dl_se))
1376 enqueue_dl_entity(dl_se, ENQUEUE_REPLENISH);
1377 else
1378 enqueue_task_dl(rq, dl_task_of(dl_se), ENQUEUE_REPLENISH);
1379 }
1380
1381 if (!is_leftmost(dl_se, &rq->dl))
1382 resched_curr(rq);
1383 }
1384
1385 /*
1386 * Because -- for now -- we share the rt bandwidth, we need to
1387 * account our runtime there too, otherwise actual rt tasks
1388 * would be able to exceed the shared quota.
1389 *
1390 * Account to the root rt group for now.
1391 *
1392 * The solution we're working towards is having the RT groups scheduled
1393 * using deadline servers -- however there's a few nasties to figure
1394 * out before that can happen.
1395 */
1396 if (rt_bandwidth_enabled()) {
1397 struct rt_rq *rt_rq = &rq->rt;
1398
1399 raw_spin_lock(&rt_rq->rt_runtime_lock);
1400 /*
1401 * We'll let actual RT tasks worry about the overflow here, we
1402 * have our own CBS to keep us inline; only account when RT
1403 * bandwidth is relevant.
1404 */
1405 if (sched_rt_bandwidth_account(rt_rq))
1406 rt_rq->rt_time += delta_exec;
1407 raw_spin_unlock(&rt_rq->rt_runtime_lock);
1408 }
1409}
1410
1411void dl_server_update(struct sched_dl_entity *dl_se, s64 delta_exec)
1412{
1413 update_curr_dl_se(dl_se->rq, dl_se, delta_exec);
1414}
1415
1416void dl_server_start(struct sched_dl_entity *dl_se)
1417{
1418 if (!dl_server(dl_se)) {
1419 dl_se->dl_server = 1;
1420 setup_new_dl_entity(dl_se);
1421 }
1422 enqueue_dl_entity(dl_se, ENQUEUE_WAKEUP);
1423}
1424
1425void dl_server_stop(struct sched_dl_entity *dl_se)
1426{
1427 dequeue_dl_entity(dl_se, DEQUEUE_SLEEP);
1428}
1429
1430void dl_server_init(struct sched_dl_entity *dl_se, struct rq *rq,
1431 dl_server_has_tasks_f has_tasks,
1432 dl_server_pick_f pick)
1433{
1434 dl_se->rq = rq;
1435 dl_se->server_has_tasks = has_tasks;
1436 dl_se->server_pick = pick;
1437}
1438
1439/*
1440 * Update the current task's runtime statistics (provided it is still
1441 * a -deadline task and has not been removed from the dl_rq).
1442 */
1443static void update_curr_dl(struct rq *rq)
1444{
1445 struct task_struct *curr = rq->curr;
1446 struct sched_dl_entity *dl_se = &curr->dl;
1447 s64 delta_exec;
1448
1449 if (!dl_task(curr) || !on_dl_rq(dl_se))
1450 return;
1451
1452 /*
1453 * Consumed budget is computed considering the time as
1454 * observed by schedulable tasks (excluding time spent
1455 * in hardirq context, etc.). Deadlines are instead
1456 * computed using hard walltime. This seems to be the more
1457 * natural solution, but the full ramifications of this
1458 * approach need further study.
1459 */
1460 delta_exec = update_curr_common(rq);
1461 update_curr_dl_se(rq, dl_se, delta_exec);
1462}
1463
1464static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
1465{
1466 struct sched_dl_entity *dl_se = container_of(timer,
1467 struct sched_dl_entity,
1468 inactive_timer);
1469 struct task_struct *p = NULL;
1470 struct rq_flags rf;
1471 struct rq *rq;
1472
1473 if (!dl_server(dl_se)) {
1474 p = dl_task_of(dl_se);
1475 rq = task_rq_lock(p, &rf);
1476 } else {
1477 rq = dl_se->rq;
1478 rq_lock(rq, &rf);
1479 }
1480
1481 sched_clock_tick();
1482 update_rq_clock(rq);
1483
1484 if (dl_server(dl_se))
1485 goto no_task;
1486
1487 if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
1488 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
1489
1490 if (READ_ONCE(p->__state) == TASK_DEAD && dl_se->dl_non_contending) {
1491 sub_running_bw(&p->dl, dl_rq_of_se(&p->dl));
1492 sub_rq_bw(&p->dl, dl_rq_of_se(&p->dl));
1493 dl_se->dl_non_contending = 0;
1494 }
1495
1496 raw_spin_lock(&dl_b->lock);
1497 __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
1498 raw_spin_unlock(&dl_b->lock);
1499 __dl_clear_params(dl_se);
1500
1501 goto unlock;
1502 }
1503
1504no_task:
1505 if (dl_se->dl_non_contending == 0)
1506 goto unlock;
1507
1508 sub_running_bw(dl_se, &rq->dl);
1509 dl_se->dl_non_contending = 0;
1510unlock:
1511
1512 if (!dl_server(dl_se)) {
1513 task_rq_unlock(rq, p, &rf);
1514 put_task_struct(p);
1515 } else {
1516 rq_unlock(rq, &rf);
1517 }
1518
1519 return HRTIMER_NORESTART;
1520}
1521
1522static void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se)
1523{
1524 struct hrtimer *timer = &dl_se->inactive_timer;
1525
1526 hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
1527 timer->function = inactive_task_timer;
1528}
1529
1530#define __node_2_dle(node) \
1531 rb_entry((node), struct sched_dl_entity, rb_node)
1532
1533#ifdef CONFIG_SMP
1534
1535static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
1536{
1537 struct rq *rq = rq_of_dl_rq(dl_rq);
1538
1539 if (dl_rq->earliest_dl.curr == 0 ||
1540 dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
1541 if (dl_rq->earliest_dl.curr == 0)
1542 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_HIGHER);
1543 dl_rq->earliest_dl.curr = deadline;
1544 cpudl_set(&rq->rd->cpudl, rq->cpu, deadline);
1545 }
1546}
1547
1548static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
1549{
1550 struct rq *rq = rq_of_dl_rq(dl_rq);
1551
1552 /*
1553 * Since we may have removed our earliest (and/or next earliest)
1554 * task we must recompute them.
1555 */
1556 if (!dl_rq->dl_nr_running) {
1557 dl_rq->earliest_dl.curr = 0;
1558 dl_rq->earliest_dl.next = 0;
1559 cpudl_clear(&rq->rd->cpudl, rq->cpu);
1560 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1561 } else {
1562 struct rb_node *leftmost = rb_first_cached(&dl_rq->root);
1563 struct sched_dl_entity *entry = __node_2_dle(leftmost);
1564
1565 dl_rq->earliest_dl.curr = entry->deadline;
1566 cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline);
1567 }
1568}
1569
1570#else
1571
1572static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
1573static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
1574
1575#endif /* CONFIG_SMP */
1576
1577static inline
1578void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
1579{
1580 u64 deadline = dl_se->deadline;
1581
1582 dl_rq->dl_nr_running++;
1583 add_nr_running(rq_of_dl_rq(dl_rq), 1);
1584
1585 inc_dl_deadline(dl_rq, deadline);
1586}
1587
1588static inline
1589void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
1590{
1591 WARN_ON(!dl_rq->dl_nr_running);
1592 dl_rq->dl_nr_running--;
1593 sub_nr_running(rq_of_dl_rq(dl_rq), 1);
1594
1595 dec_dl_deadline(dl_rq, dl_se->deadline);
1596}
1597
1598static inline bool __dl_less(struct rb_node *a, const struct rb_node *b)
1599{
1600 return dl_time_before(__node_2_dle(a)->deadline, __node_2_dle(b)->deadline);
1601}
1602
1603static inline struct sched_statistics *
1604__schedstats_from_dl_se(struct sched_dl_entity *dl_se)
1605{
1606 return &dl_task_of(dl_se)->stats;
1607}
1608
1609static inline void
1610update_stats_wait_start_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se)
1611{
1612 struct sched_statistics *stats;
1613
1614 if (!schedstat_enabled())
1615 return;
1616
1617 stats = __schedstats_from_dl_se(dl_se);
1618 __update_stats_wait_start(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats);
1619}
1620
1621static inline void
1622update_stats_wait_end_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se)
1623{
1624 struct sched_statistics *stats;
1625
1626 if (!schedstat_enabled())
1627 return;
1628
1629 stats = __schedstats_from_dl_se(dl_se);
1630 __update_stats_wait_end(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats);
1631}
1632
1633static inline void
1634update_stats_enqueue_sleeper_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se)
1635{
1636 struct sched_statistics *stats;
1637
1638 if (!schedstat_enabled())
1639 return;
1640
1641 stats = __schedstats_from_dl_se(dl_se);
1642 __update_stats_enqueue_sleeper(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats);
1643}
1644
1645static inline void
1646update_stats_enqueue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se,
1647 int flags)
1648{
1649 if (!schedstat_enabled())
1650 return;
1651
1652 if (flags & ENQUEUE_WAKEUP)
1653 update_stats_enqueue_sleeper_dl(dl_rq, dl_se);
1654}
1655
1656static inline void
1657update_stats_dequeue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se,
1658 int flags)
1659{
1660 struct task_struct *p = dl_task_of(dl_se);
1661
1662 if (!schedstat_enabled())
1663 return;
1664
1665 if ((flags & DEQUEUE_SLEEP)) {
1666 unsigned int state;
1667
1668 state = READ_ONCE(p->__state);
1669 if (state & TASK_INTERRUPTIBLE)
1670 __schedstat_set(p->stats.sleep_start,
1671 rq_clock(rq_of_dl_rq(dl_rq)));
1672
1673 if (state & TASK_UNINTERRUPTIBLE)
1674 __schedstat_set(p->stats.block_start,
1675 rq_clock(rq_of_dl_rq(dl_rq)));
1676 }
1677}
1678
1679static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
1680{
1681 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1682
1683 WARN_ON_ONCE(!RB_EMPTY_NODE(&dl_se->rb_node));
1684
1685 rb_add_cached(&dl_se->rb_node, &dl_rq->root, __dl_less);
1686
1687 inc_dl_tasks(dl_se, dl_rq);
1688}
1689
1690static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
1691{
1692 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1693
1694 if (RB_EMPTY_NODE(&dl_se->rb_node))
1695 return;
1696
1697 rb_erase_cached(&dl_se->rb_node, &dl_rq->root);
1698
1699 RB_CLEAR_NODE(&dl_se->rb_node);
1700
1701 dec_dl_tasks(dl_se, dl_rq);
1702}
1703
1704static void
1705enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags)
1706{
1707 WARN_ON_ONCE(on_dl_rq(dl_se));
1708
1709 update_stats_enqueue_dl(dl_rq_of_se(dl_se), dl_se, flags);
1710
1711 /*
1712 * Check if a constrained deadline task was activated
1713 * after the deadline but before the next period.
1714 * If that is the case, the task will be throttled and
1715 * the replenishment timer will be set to the next period.
1716 */
1717 if (!dl_se->dl_throttled && !dl_is_implicit(dl_se))
1718 dl_check_constrained_dl(dl_se);
1719
1720 if (flags & (ENQUEUE_RESTORE|ENQUEUE_MIGRATING)) {
1721 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1722
1723 add_rq_bw(dl_se, dl_rq);
1724 add_running_bw(dl_se, dl_rq);
1725 }
1726
1727 /*
1728 * If p is throttled, we do not enqueue it. In fact, if it exhausted
1729 * its budget it needs a replenishment and, since it now is on
1730 * its rq, the bandwidth timer callback (which clearly has not
1731 * run yet) will take care of this.
1732 * However, the active utilization does not depend on the fact
1733 * that the task is on the runqueue or not (but depends on the
1734 * task's state - in GRUB parlance, "inactive" vs "active contending").
1735 * In other words, even if a task is throttled its utilization must
1736 * be counted in the active utilization; hence, we need to call
1737 * add_running_bw().
1738 */
1739 if (dl_se->dl_throttled && !(flags & ENQUEUE_REPLENISH)) {
1740 if (flags & ENQUEUE_WAKEUP)
1741 task_contending(dl_se, flags);
1742
1743 return;
1744 }
1745
1746 /*
1747 * If this is a wakeup or a new instance, the scheduling
1748 * parameters of the task might need updating. Otherwise,
1749 * we want a replenishment of its runtime.
1750 */
1751 if (flags & ENQUEUE_WAKEUP) {
1752 task_contending(dl_se, flags);
1753 update_dl_entity(dl_se);
1754 } else if (flags & ENQUEUE_REPLENISH) {
1755 replenish_dl_entity(dl_se);
1756 } else if ((flags & ENQUEUE_RESTORE) &&
1757 dl_time_before(dl_se->deadline, rq_clock(rq_of_dl_se(dl_se)))) {
1758 setup_new_dl_entity(dl_se);
1759 }
1760
1761 __enqueue_dl_entity(dl_se);
1762}
1763
1764static void dequeue_dl_entity(struct sched_dl_entity *dl_se, int flags)
1765{
1766 __dequeue_dl_entity(dl_se);
1767
1768 if (flags & (DEQUEUE_SAVE|DEQUEUE_MIGRATING)) {
1769 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1770
1771 sub_running_bw(dl_se, dl_rq);
1772 sub_rq_bw(dl_se, dl_rq);
1773 }
1774
1775 /*
1776 * This check allows to start the inactive timer (or to immediately
1777 * decrease the active utilization, if needed) in two cases:
1778 * when the task blocks and when it is terminating
1779 * (p->state == TASK_DEAD). We can handle the two cases in the same
1780 * way, because from GRUB's point of view the same thing is happening
1781 * (the task moves from "active contending" to "active non contending"
1782 * or "inactive")
1783 */
1784 if (flags & DEQUEUE_SLEEP)
1785 task_non_contending(dl_se);
1786}
1787
1788static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
1789{
1790 if (is_dl_boosted(&p->dl)) {
1791 /*
1792 * Because of delays in the detection of the overrun of a
1793 * thread's runtime, it might be the case that a thread
1794 * goes to sleep in a rt mutex with negative runtime. As
1795 * a consequence, the thread will be throttled.
1796 *
1797 * While waiting for the mutex, this thread can also be
1798 * boosted via PI, resulting in a thread that is throttled
1799 * and boosted at the same time.
1800 *
1801 * In this case, the boost overrides the throttle.
1802 */
1803 if (p->dl.dl_throttled) {
1804 /*
1805 * The replenish timer needs to be canceled. No
1806 * problem if it fires concurrently: boosted threads
1807 * are ignored in dl_task_timer().
1808 */
1809 hrtimer_try_to_cancel(&p->dl.dl_timer);
1810 p->dl.dl_throttled = 0;
1811 }
1812 } else if (!dl_prio(p->normal_prio)) {
1813 /*
1814 * Special case in which we have a !SCHED_DEADLINE task that is going
1815 * to be deboosted, but exceeds its runtime while doing so. No point in
1816 * replenishing it, as it's going to return back to its original
1817 * scheduling class after this. If it has been throttled, we need to
1818 * clear the flag, otherwise the task may wake up as throttled after
1819 * being boosted again with no means to replenish the runtime and clear
1820 * the throttle.
1821 */
1822 p->dl.dl_throttled = 0;
1823 if (!(flags & ENQUEUE_REPLENISH))
1824 printk_deferred_once("sched: DL de-boosted task PID %d: REPLENISH flag missing\n",
1825 task_pid_nr(p));
1826
1827 return;
1828 }
1829
1830 check_schedstat_required();
1831 update_stats_wait_start_dl(dl_rq_of_se(&p->dl), &p->dl);
1832
1833 if (p->on_rq == TASK_ON_RQ_MIGRATING)
1834 flags |= ENQUEUE_MIGRATING;
1835
1836 enqueue_dl_entity(&p->dl, flags);
1837
1838 if (dl_server(&p->dl))
1839 return;
1840
1841 if (!task_current(rq, p) && !p->dl.dl_throttled && p->nr_cpus_allowed > 1)
1842 enqueue_pushable_dl_task(rq, p);
1843}
1844
1845static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
1846{
1847 update_curr_dl(rq);
1848
1849 if (p->on_rq == TASK_ON_RQ_MIGRATING)
1850 flags |= DEQUEUE_MIGRATING;
1851
1852 dequeue_dl_entity(&p->dl, flags);
1853 if (!p->dl.dl_throttled && !dl_server(&p->dl))
1854 dequeue_pushable_dl_task(rq, p);
1855}
1856
1857/*
1858 * Yield task semantic for -deadline tasks is:
1859 *
1860 * get off from the CPU until our next instance, with
1861 * a new runtime. This is of little use now, since we
1862 * don't have a bandwidth reclaiming mechanism. Anyway,
1863 * bandwidth reclaiming is planned for the future, and
1864 * yield_task_dl will indicate that some spare budget
1865 * is available for other task instances to use it.
1866 */
1867static void yield_task_dl(struct rq *rq)
1868{
1869 /*
1870 * We make the task go to sleep until its current deadline by
1871 * forcing its runtime to zero. This way, update_curr_dl() stops
1872 * it and the bandwidth timer will wake it up and will give it
1873 * new scheduling parameters (thanks to dl_yielded=1).
1874 */
1875 rq->curr->dl.dl_yielded = 1;
1876
1877 update_rq_clock(rq);
1878 update_curr_dl(rq);
1879 /*
1880 * Tell update_rq_clock() that we've just updated,
1881 * so we don't do microscopic update in schedule()
1882 * and double the fastpath cost.
1883 */
1884 rq_clock_skip_update(rq);
1885}
1886
1887#ifdef CONFIG_SMP
1888
1889static inline bool dl_task_is_earliest_deadline(struct task_struct *p,
1890 struct rq *rq)
1891{
1892 return (!rq->dl.dl_nr_running ||
1893 dl_time_before(p->dl.deadline,
1894 rq->dl.earliest_dl.curr));
1895}
1896
1897static int find_later_rq(struct task_struct *task);
1898
1899static int
1900select_task_rq_dl(struct task_struct *p, int cpu, int flags)
1901{
1902 struct task_struct *curr;
1903 bool select_rq;
1904 struct rq *rq;
1905
1906 if (!(flags & WF_TTWU))
1907 goto out;
1908
1909 rq = cpu_rq(cpu);
1910
1911 rcu_read_lock();
1912 curr = READ_ONCE(rq->curr); /* unlocked access */
1913
1914 /*
1915 * If we are dealing with a -deadline task, we must
1916 * decide where to wake it up.
1917 * If it has a later deadline and the current task
1918 * on this rq can't move (provided the waking task
1919 * can!) we prefer to send it somewhere else. On the
1920 * other hand, if it has a shorter deadline, we
1921 * try to make it stay here, it might be important.
1922 */
1923 select_rq = unlikely(dl_task(curr)) &&
1924 (curr->nr_cpus_allowed < 2 ||
1925 !dl_entity_preempt(&p->dl, &curr->dl)) &&
1926 p->nr_cpus_allowed > 1;
1927
1928 /*
1929 * Take the capacity of the CPU into account to
1930 * ensure it fits the requirement of the task.
1931 */
1932 if (sched_asym_cpucap_active())
1933 select_rq |= !dl_task_fits_capacity(p, cpu);
1934
1935 if (select_rq) {
1936 int target = find_later_rq(p);
1937
1938 if (target != -1 &&
1939 dl_task_is_earliest_deadline(p, cpu_rq(target)))
1940 cpu = target;
1941 }
1942 rcu_read_unlock();
1943
1944out:
1945 return cpu;
1946}
1947
1948static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused)
1949{
1950 struct rq_flags rf;
1951 struct rq *rq;
1952
1953 if (READ_ONCE(p->__state) != TASK_WAKING)
1954 return;
1955
1956 rq = task_rq(p);
1957 /*
1958 * Since p->state == TASK_WAKING, set_task_cpu() has been called
1959 * from try_to_wake_up(). Hence, p->pi_lock is locked, but
1960 * rq->lock is not... So, lock it
1961 */
1962 rq_lock(rq, &rf);
1963 if (p->dl.dl_non_contending) {
1964 update_rq_clock(rq);
1965 sub_running_bw(&p->dl, &rq->dl);
1966 p->dl.dl_non_contending = 0;
1967 /*
1968 * If the timer handler is currently running and the
1969 * timer cannot be canceled, inactive_task_timer()
1970 * will see that dl_not_contending is not set, and
1971 * will not touch the rq's active utilization,
1972 * so we are still safe.
1973 */
1974 if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
1975 put_task_struct(p);
1976 }
1977 sub_rq_bw(&p->dl, &rq->dl);
1978 rq_unlock(rq, &rf);
1979}
1980
1981static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
1982{
1983 /*
1984 * Current can't be migrated, useless to reschedule,
1985 * let's hope p can move out.
1986 */
1987 if (rq->curr->nr_cpus_allowed == 1 ||
1988 !cpudl_find(&rq->rd->cpudl, rq->curr, NULL))
1989 return;
1990
1991 /*
1992 * p is migratable, so let's not schedule it and
1993 * see if it is pushed or pulled somewhere else.
1994 */
1995 if (p->nr_cpus_allowed != 1 &&
1996 cpudl_find(&rq->rd->cpudl, p, NULL))
1997 return;
1998
1999 resched_curr(rq);
2000}
2001
2002static int balance_dl(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
2003{
2004 if (!on_dl_rq(&p->dl) && need_pull_dl_task(rq, p)) {
2005 /*
2006 * This is OK, because current is on_cpu, which avoids it being
2007 * picked for load-balance and preemption/IRQs are still
2008 * disabled avoiding further scheduler activity on it and we've
2009 * not yet started the picking loop.
2010 */
2011 rq_unpin_lock(rq, rf);
2012 pull_dl_task(rq);
2013 rq_repin_lock(rq, rf);
2014 }
2015
2016 return sched_stop_runnable(rq) || sched_dl_runnable(rq);
2017}
2018#endif /* CONFIG_SMP */
2019
2020/*
2021 * Only called when both the current and waking task are -deadline
2022 * tasks.
2023 */
2024static void wakeup_preempt_dl(struct rq *rq, struct task_struct *p,
2025 int flags)
2026{
2027 if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
2028 resched_curr(rq);
2029 return;
2030 }
2031
2032#ifdef CONFIG_SMP
2033 /*
2034 * In the unlikely case current and p have the same deadline
2035 * let us try to decide what's the best thing to do...
2036 */
2037 if ((p->dl.deadline == rq->curr->dl.deadline) &&
2038 !test_tsk_need_resched(rq->curr))
2039 check_preempt_equal_dl(rq, p);
2040#endif /* CONFIG_SMP */
2041}
2042
2043#ifdef CONFIG_SCHED_HRTICK
2044static void start_hrtick_dl(struct rq *rq, struct sched_dl_entity *dl_se)
2045{
2046 hrtick_start(rq, dl_se->runtime);
2047}
2048#else /* !CONFIG_SCHED_HRTICK */
2049static void start_hrtick_dl(struct rq *rq, struct sched_dl_entity *dl_se)
2050{
2051}
2052#endif
2053
2054static void set_next_task_dl(struct rq *rq, struct task_struct *p, bool first)
2055{
2056 struct sched_dl_entity *dl_se = &p->dl;
2057 struct dl_rq *dl_rq = &rq->dl;
2058
2059 p->se.exec_start = rq_clock_task(rq);
2060 if (on_dl_rq(&p->dl))
2061 update_stats_wait_end_dl(dl_rq, dl_se);
2062
2063 /* You can't push away the running task */
2064 dequeue_pushable_dl_task(rq, p);
2065
2066 if (!first)
2067 return;
2068
2069 if (rq->curr->sched_class != &dl_sched_class)
2070 update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
2071
2072 deadline_queue_push_tasks(rq);
2073}
2074
2075static struct sched_dl_entity *pick_next_dl_entity(struct dl_rq *dl_rq)
2076{
2077 struct rb_node *left = rb_first_cached(&dl_rq->root);
2078
2079 if (!left)
2080 return NULL;
2081
2082 return __node_2_dle(left);
2083}
2084
2085static struct task_struct *pick_task_dl(struct rq *rq)
2086{
2087 struct sched_dl_entity *dl_se;
2088 struct dl_rq *dl_rq = &rq->dl;
2089 struct task_struct *p;
2090
2091again:
2092 if (!sched_dl_runnable(rq))
2093 return NULL;
2094
2095 dl_se = pick_next_dl_entity(dl_rq);
2096 WARN_ON_ONCE(!dl_se);
2097
2098 if (dl_server(dl_se)) {
2099 p = dl_se->server_pick(dl_se);
2100 if (!p) {
2101 WARN_ON_ONCE(1);
2102 dl_se->dl_yielded = 1;
2103 update_curr_dl_se(rq, dl_se, 0);
2104 goto again;
2105 }
2106 p->dl_server = dl_se;
2107 } else {
2108 p = dl_task_of(dl_se);
2109 }
2110
2111 return p;
2112}
2113
2114static struct task_struct *pick_next_task_dl(struct rq *rq)
2115{
2116 struct task_struct *p;
2117
2118 p = pick_task_dl(rq);
2119 if (!p)
2120 return p;
2121
2122 if (!p->dl_server)
2123 set_next_task_dl(rq, p, true);
2124
2125 if (hrtick_enabled(rq))
2126 start_hrtick_dl(rq, &p->dl);
2127
2128 return p;
2129}
2130
2131static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
2132{
2133 struct sched_dl_entity *dl_se = &p->dl;
2134 struct dl_rq *dl_rq = &rq->dl;
2135
2136 if (on_dl_rq(&p->dl))
2137 update_stats_wait_start_dl(dl_rq, dl_se);
2138
2139 update_curr_dl(rq);
2140
2141 update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1);
2142 if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
2143 enqueue_pushable_dl_task(rq, p);
2144}
2145
2146/*
2147 * scheduler tick hitting a task of our scheduling class.
2148 *
2149 * NOTE: This function can be called remotely by the tick offload that
2150 * goes along full dynticks. Therefore no local assumption can be made
2151 * and everything must be accessed through the @rq and @curr passed in
2152 * parameters.
2153 */
2154static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
2155{
2156 update_curr_dl(rq);
2157
2158 update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1);
2159 /*
2160 * Even when we have runtime, update_curr_dl() might have resulted in us
2161 * not being the leftmost task anymore. In that case NEED_RESCHED will
2162 * be set and schedule() will start a new hrtick for the next task.
2163 */
2164 if (hrtick_enabled_dl(rq) && queued && p->dl.runtime > 0 &&
2165 is_leftmost(&p->dl, &rq->dl))
2166 start_hrtick_dl(rq, &p->dl);
2167}
2168
2169static void task_fork_dl(struct task_struct *p)
2170{
2171 /*
2172 * SCHED_DEADLINE tasks cannot fork and this is achieved through
2173 * sched_fork()
2174 */
2175}
2176
2177#ifdef CONFIG_SMP
2178
2179/* Only try algorithms three times */
2180#define DL_MAX_TRIES 3
2181
2182static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
2183{
2184 if (!task_on_cpu(rq, p) &&
2185 cpumask_test_cpu(cpu, &p->cpus_mask))
2186 return 1;
2187 return 0;
2188}
2189
2190/*
2191 * Return the earliest pushable rq's task, which is suitable to be executed
2192 * on the CPU, NULL otherwise:
2193 */
2194static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu)
2195{
2196 struct task_struct *p = NULL;
2197 struct rb_node *next_node;
2198
2199 if (!has_pushable_dl_tasks(rq))
2200 return NULL;
2201
2202 next_node = rb_first_cached(&rq->dl.pushable_dl_tasks_root);
2203
2204next_node:
2205 if (next_node) {
2206 p = __node_2_pdl(next_node);
2207
2208 if (pick_dl_task(rq, p, cpu))
2209 return p;
2210
2211 next_node = rb_next(next_node);
2212 goto next_node;
2213 }
2214
2215 return NULL;
2216}
2217
2218static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
2219
2220static int find_later_rq(struct task_struct *task)
2221{
2222 struct sched_domain *sd;
2223 struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl);
2224 int this_cpu = smp_processor_id();
2225 int cpu = task_cpu(task);
2226
2227 /* Make sure the mask is initialized first */
2228 if (unlikely(!later_mask))
2229 return -1;
2230
2231 if (task->nr_cpus_allowed == 1)
2232 return -1;
2233
2234 /*
2235 * We have to consider system topology and task affinity
2236 * first, then we can look for a suitable CPU.
2237 */
2238 if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask))
2239 return -1;
2240
2241 /*
2242 * If we are here, some targets have been found, including
2243 * the most suitable which is, among the runqueues where the
2244 * current tasks have later deadlines than the task's one, the
2245 * rq with the latest possible one.
2246 *
2247 * Now we check how well this matches with task's
2248 * affinity and system topology.
2249 *
2250 * The last CPU where the task run is our first
2251 * guess, since it is most likely cache-hot there.
2252 */
2253 if (cpumask_test_cpu(cpu, later_mask))
2254 return cpu;
2255 /*
2256 * Check if this_cpu is to be skipped (i.e., it is
2257 * not in the mask) or not.
2258 */
2259 if (!cpumask_test_cpu(this_cpu, later_mask))
2260 this_cpu = -1;
2261
2262 rcu_read_lock();
2263 for_each_domain(cpu, sd) {
2264 if (sd->flags & SD_WAKE_AFFINE) {
2265 int best_cpu;
2266
2267 /*
2268 * If possible, preempting this_cpu is
2269 * cheaper than migrating.
2270 */
2271 if (this_cpu != -1 &&
2272 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
2273 rcu_read_unlock();
2274 return this_cpu;
2275 }
2276
2277 best_cpu = cpumask_any_and_distribute(later_mask,
2278 sched_domain_span(sd));
2279 /*
2280 * Last chance: if a CPU being in both later_mask
2281 * and current sd span is valid, that becomes our
2282 * choice. Of course, the latest possible CPU is
2283 * already under consideration through later_mask.
2284 */
2285 if (best_cpu < nr_cpu_ids) {
2286 rcu_read_unlock();
2287 return best_cpu;
2288 }
2289 }
2290 }
2291 rcu_read_unlock();
2292
2293 /*
2294 * At this point, all our guesses failed, we just return
2295 * 'something', and let the caller sort the things out.
2296 */
2297 if (this_cpu != -1)
2298 return this_cpu;
2299
2300 cpu = cpumask_any_distribute(later_mask);
2301 if (cpu < nr_cpu_ids)
2302 return cpu;
2303
2304 return -1;
2305}
2306
2307/* Locks the rq it finds */
2308static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
2309{
2310 struct rq *later_rq = NULL;
2311 int tries;
2312 int cpu;
2313
2314 for (tries = 0; tries < DL_MAX_TRIES; tries++) {
2315 cpu = find_later_rq(task);
2316
2317 if ((cpu == -1) || (cpu == rq->cpu))
2318 break;
2319
2320 later_rq = cpu_rq(cpu);
2321
2322 if (!dl_task_is_earliest_deadline(task, later_rq)) {
2323 /*
2324 * Target rq has tasks of equal or earlier deadline,
2325 * retrying does not release any lock and is unlikely
2326 * to yield a different result.
2327 */
2328 later_rq = NULL;
2329 break;
2330 }
2331
2332 /* Retry if something changed. */
2333 if (double_lock_balance(rq, later_rq)) {
2334 if (unlikely(task_rq(task) != rq ||
2335 !cpumask_test_cpu(later_rq->cpu, &task->cpus_mask) ||
2336 task_on_cpu(rq, task) ||
2337 !dl_task(task) ||
2338 is_migration_disabled(task) ||
2339 !task_on_rq_queued(task))) {
2340 double_unlock_balance(rq, later_rq);
2341 later_rq = NULL;
2342 break;
2343 }
2344 }
2345
2346 /*
2347 * If the rq we found has no -deadline task, or
2348 * its earliest one has a later deadline than our
2349 * task, the rq is a good one.
2350 */
2351 if (dl_task_is_earliest_deadline(task, later_rq))
2352 break;
2353
2354 /* Otherwise we try again. */
2355 double_unlock_balance(rq, later_rq);
2356 later_rq = NULL;
2357 }
2358
2359 return later_rq;
2360}
2361
2362static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
2363{
2364 struct task_struct *p;
2365
2366 if (!has_pushable_dl_tasks(rq))
2367 return NULL;
2368
2369 p = __node_2_pdl(rb_first_cached(&rq->dl.pushable_dl_tasks_root));
2370
2371 WARN_ON_ONCE(rq->cpu != task_cpu(p));
2372 WARN_ON_ONCE(task_current(rq, p));
2373 WARN_ON_ONCE(p->nr_cpus_allowed <= 1);
2374
2375 WARN_ON_ONCE(!task_on_rq_queued(p));
2376 WARN_ON_ONCE(!dl_task(p));
2377
2378 return p;
2379}
2380
2381/*
2382 * See if the non running -deadline tasks on this rq
2383 * can be sent to some other CPU where they can preempt
2384 * and start executing.
2385 */
2386static int push_dl_task(struct rq *rq)
2387{
2388 struct task_struct *next_task;
2389 struct rq *later_rq;
2390 int ret = 0;
2391
2392 next_task = pick_next_pushable_dl_task(rq);
2393 if (!next_task)
2394 return 0;
2395
2396retry:
2397 /*
2398 * If next_task preempts rq->curr, and rq->curr
2399 * can move away, it makes sense to just reschedule
2400 * without going further in pushing next_task.
2401 */
2402 if (dl_task(rq->curr) &&
2403 dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
2404 rq->curr->nr_cpus_allowed > 1) {
2405 resched_curr(rq);
2406 return 0;
2407 }
2408
2409 if (is_migration_disabled(next_task))
2410 return 0;
2411
2412 if (WARN_ON(next_task == rq->curr))
2413 return 0;
2414
2415 /* We might release rq lock */
2416 get_task_struct(next_task);
2417
2418 /* Will lock the rq it'll find */
2419 later_rq = find_lock_later_rq(next_task, rq);
2420 if (!later_rq) {
2421 struct task_struct *task;
2422
2423 /*
2424 * We must check all this again, since
2425 * find_lock_later_rq releases rq->lock and it is
2426 * then possible that next_task has migrated.
2427 */
2428 task = pick_next_pushable_dl_task(rq);
2429 if (task == next_task) {
2430 /*
2431 * The task is still there. We don't try
2432 * again, some other CPU will pull it when ready.
2433 */
2434 goto out;
2435 }
2436
2437 if (!task)
2438 /* No more tasks */
2439 goto out;
2440
2441 put_task_struct(next_task);
2442 next_task = task;
2443 goto retry;
2444 }
2445
2446 deactivate_task(rq, next_task, 0);
2447 set_task_cpu(next_task, later_rq->cpu);
2448 activate_task(later_rq, next_task, 0);
2449 ret = 1;
2450
2451 resched_curr(later_rq);
2452
2453 double_unlock_balance(rq, later_rq);
2454
2455out:
2456 put_task_struct(next_task);
2457
2458 return ret;
2459}
2460
2461static void push_dl_tasks(struct rq *rq)
2462{
2463 /* push_dl_task() will return true if it moved a -deadline task */
2464 while (push_dl_task(rq))
2465 ;
2466}
2467
2468static void pull_dl_task(struct rq *this_rq)
2469{
2470 int this_cpu = this_rq->cpu, cpu;
2471 struct task_struct *p, *push_task;
2472 bool resched = false;
2473 struct rq *src_rq;
2474 u64 dmin = LONG_MAX;
2475
2476 if (likely(!dl_overloaded(this_rq)))
2477 return;
2478
2479 /*
2480 * Match the barrier from dl_set_overloaded; this guarantees that if we
2481 * see overloaded we must also see the dlo_mask bit.
2482 */
2483 smp_rmb();
2484
2485 for_each_cpu(cpu, this_rq->rd->dlo_mask) {
2486 if (this_cpu == cpu)
2487 continue;
2488
2489 src_rq = cpu_rq(cpu);
2490
2491 /*
2492 * It looks racy, abd it is! However, as in sched_rt.c,
2493 * we are fine with this.
2494 */
2495 if (this_rq->dl.dl_nr_running &&
2496 dl_time_before(this_rq->dl.earliest_dl.curr,
2497 src_rq->dl.earliest_dl.next))
2498 continue;
2499
2500 /* Might drop this_rq->lock */
2501 push_task = NULL;
2502 double_lock_balance(this_rq, src_rq);
2503
2504 /*
2505 * If there are no more pullable tasks on the
2506 * rq, we're done with it.
2507 */
2508 if (src_rq->dl.dl_nr_running <= 1)
2509 goto skip;
2510
2511 p = pick_earliest_pushable_dl_task(src_rq, this_cpu);
2512
2513 /*
2514 * We found a task to be pulled if:
2515 * - it preempts our current (if there's one),
2516 * - it will preempt the last one we pulled (if any).
2517 */
2518 if (p && dl_time_before(p->dl.deadline, dmin) &&
2519 dl_task_is_earliest_deadline(p, this_rq)) {
2520 WARN_ON(p == src_rq->curr);
2521 WARN_ON(!task_on_rq_queued(p));
2522
2523 /*
2524 * Then we pull iff p has actually an earlier
2525 * deadline than the current task of its runqueue.
2526 */
2527 if (dl_time_before(p->dl.deadline,
2528 src_rq->curr->dl.deadline))
2529 goto skip;
2530
2531 if (is_migration_disabled(p)) {
2532 push_task = get_push_task(src_rq);
2533 } else {
2534 deactivate_task(src_rq, p, 0);
2535 set_task_cpu(p, this_cpu);
2536 activate_task(this_rq, p, 0);
2537 dmin = p->dl.deadline;
2538 resched = true;
2539 }
2540
2541 /* Is there any other task even earlier? */
2542 }
2543skip:
2544 double_unlock_balance(this_rq, src_rq);
2545
2546 if (push_task) {
2547 preempt_disable();
2548 raw_spin_rq_unlock(this_rq);
2549 stop_one_cpu_nowait(src_rq->cpu, push_cpu_stop,
2550 push_task, &src_rq->push_work);
2551 preempt_enable();
2552 raw_spin_rq_lock(this_rq);
2553 }
2554 }
2555
2556 if (resched)
2557 resched_curr(this_rq);
2558}
2559
2560/*
2561 * Since the task is not running and a reschedule is not going to happen
2562 * anytime soon on its runqueue, we try pushing it away now.
2563 */
2564static void task_woken_dl(struct rq *rq, struct task_struct *p)
2565{
2566 if (!task_on_cpu(rq, p) &&
2567 !test_tsk_need_resched(rq->curr) &&
2568 p->nr_cpus_allowed > 1 &&
2569 dl_task(rq->curr) &&
2570 (rq->curr->nr_cpus_allowed < 2 ||
2571 !dl_entity_preempt(&p->dl, &rq->curr->dl))) {
2572 push_dl_tasks(rq);
2573 }
2574}
2575
2576static void set_cpus_allowed_dl(struct task_struct *p,
2577 struct affinity_context *ctx)
2578{
2579 struct root_domain *src_rd;
2580 struct rq *rq;
2581
2582 WARN_ON_ONCE(!dl_task(p));
2583
2584 rq = task_rq(p);
2585 src_rd = rq->rd;
2586 /*
2587 * Migrating a SCHED_DEADLINE task between exclusive
2588 * cpusets (different root_domains) entails a bandwidth
2589 * update. We already made space for us in the destination
2590 * domain (see cpuset_can_attach()).
2591 */
2592 if (!cpumask_intersects(src_rd->span, ctx->new_mask)) {
2593 struct dl_bw *src_dl_b;
2594
2595 src_dl_b = dl_bw_of(cpu_of(rq));
2596 /*
2597 * We now free resources of the root_domain we are migrating
2598 * off. In the worst case, sched_setattr() may temporary fail
2599 * until we complete the update.
2600 */
2601 raw_spin_lock(&src_dl_b->lock);
2602 __dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
2603 raw_spin_unlock(&src_dl_b->lock);
2604 }
2605
2606 set_cpus_allowed_common(p, ctx);
2607}
2608
2609/* Assumes rq->lock is held */
2610static void rq_online_dl(struct rq *rq)
2611{
2612 if (rq->dl.overloaded)
2613 dl_set_overload(rq);
2614
2615 cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
2616 if (rq->dl.dl_nr_running > 0)
2617 cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr);
2618}
2619
2620/* Assumes rq->lock is held */
2621static void rq_offline_dl(struct rq *rq)
2622{
2623 if (rq->dl.overloaded)
2624 dl_clear_overload(rq);
2625
2626 cpudl_clear(&rq->rd->cpudl, rq->cpu);
2627 cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
2628}
2629
2630void __init init_sched_dl_class(void)
2631{
2632 unsigned int i;
2633
2634 for_each_possible_cpu(i)
2635 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
2636 GFP_KERNEL, cpu_to_node(i));
2637}
2638
2639void dl_add_task_root_domain(struct task_struct *p)
2640{
2641 struct rq_flags rf;
2642 struct rq *rq;
2643 struct dl_bw *dl_b;
2644
2645 raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
2646 if (!dl_task(p)) {
2647 raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
2648 return;
2649 }
2650
2651 rq = __task_rq_lock(p, &rf);
2652
2653 dl_b = &rq->rd->dl_bw;
2654 raw_spin_lock(&dl_b->lock);
2655
2656 __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span));
2657
2658 raw_spin_unlock(&dl_b->lock);
2659
2660 task_rq_unlock(rq, p, &rf);
2661}
2662
2663void dl_clear_root_domain(struct root_domain *rd)
2664{
2665 unsigned long flags;
2666
2667 raw_spin_lock_irqsave(&rd->dl_bw.lock, flags);
2668 rd->dl_bw.total_bw = 0;
2669 raw_spin_unlock_irqrestore(&rd->dl_bw.lock, flags);
2670}
2671
2672#endif /* CONFIG_SMP */
2673
2674static void switched_from_dl(struct rq *rq, struct task_struct *p)
2675{
2676 /*
2677 * task_non_contending() can start the "inactive timer" (if the 0-lag
2678 * time is in the future). If the task switches back to dl before
2679 * the "inactive timer" fires, it can continue to consume its current
2680 * runtime using its current deadline. If it stays outside of
2681 * SCHED_DEADLINE until the 0-lag time passes, inactive_task_timer()
2682 * will reset the task parameters.
2683 */
2684 if (task_on_rq_queued(p) && p->dl.dl_runtime)
2685 task_non_contending(&p->dl);
2686
2687 /*
2688 * In case a task is setscheduled out from SCHED_DEADLINE we need to
2689 * keep track of that on its cpuset (for correct bandwidth tracking).
2690 */
2691 dec_dl_tasks_cs(p);
2692
2693 if (!task_on_rq_queued(p)) {
2694 /*
2695 * Inactive timer is armed. However, p is leaving DEADLINE and
2696 * might migrate away from this rq while continuing to run on
2697 * some other class. We need to remove its contribution from
2698 * this rq running_bw now, or sub_rq_bw (below) will complain.
2699 */
2700 if (p->dl.dl_non_contending)
2701 sub_running_bw(&p->dl, &rq->dl);
2702 sub_rq_bw(&p->dl, &rq->dl);
2703 }
2704
2705 /*
2706 * We cannot use inactive_task_timer() to invoke sub_running_bw()
2707 * at the 0-lag time, because the task could have been migrated
2708 * while SCHED_OTHER in the meanwhile.
2709 */
2710 if (p->dl.dl_non_contending)
2711 p->dl.dl_non_contending = 0;
2712
2713 /*
2714 * Since this might be the only -deadline task on the rq,
2715 * this is the right place to try to pull some other one
2716 * from an overloaded CPU, if any.
2717 */
2718 if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
2719 return;
2720
2721 deadline_queue_pull_task(rq);
2722}
2723
2724/*
2725 * When switching to -deadline, we may overload the rq, then
2726 * we try to push someone off, if possible.
2727 */
2728static void switched_to_dl(struct rq *rq, struct task_struct *p)
2729{
2730 if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
2731 put_task_struct(p);
2732
2733 /*
2734 * In case a task is setscheduled to SCHED_DEADLINE we need to keep
2735 * track of that on its cpuset (for correct bandwidth tracking).
2736 */
2737 inc_dl_tasks_cs(p);
2738
2739 /* If p is not queued we will update its parameters at next wakeup. */
2740 if (!task_on_rq_queued(p)) {
2741 add_rq_bw(&p->dl, &rq->dl);
2742
2743 return;
2744 }
2745
2746 if (rq->curr != p) {
2747#ifdef CONFIG_SMP
2748 if (p->nr_cpus_allowed > 1 && rq->dl.overloaded)
2749 deadline_queue_push_tasks(rq);
2750#endif
2751 if (dl_task(rq->curr))
2752 wakeup_preempt_dl(rq, p, 0);
2753 else
2754 resched_curr(rq);
2755 } else {
2756 update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
2757 }
2758}
2759
2760/*
2761 * If the scheduling parameters of a -deadline task changed,
2762 * a push or pull operation might be needed.
2763 */
2764static void prio_changed_dl(struct rq *rq, struct task_struct *p,
2765 int oldprio)
2766{
2767 if (!task_on_rq_queued(p))
2768 return;
2769
2770#ifdef CONFIG_SMP
2771 /*
2772 * This might be too much, but unfortunately
2773 * we don't have the old deadline value, and
2774 * we can't argue if the task is increasing
2775 * or lowering its prio, so...
2776 */
2777 if (!rq->dl.overloaded)
2778 deadline_queue_pull_task(rq);
2779
2780 if (task_current(rq, p)) {
2781 /*
2782 * If we now have a earlier deadline task than p,
2783 * then reschedule, provided p is still on this
2784 * runqueue.
2785 */
2786 if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline))
2787 resched_curr(rq);
2788 } else {
2789 /*
2790 * Current may not be deadline in case p was throttled but we
2791 * have just replenished it (e.g. rt_mutex_setprio()).
2792 *
2793 * Otherwise, if p was given an earlier deadline, reschedule.
2794 */
2795 if (!dl_task(rq->curr) ||
2796 dl_time_before(p->dl.deadline, rq->curr->dl.deadline))
2797 resched_curr(rq);
2798 }
2799#else
2800 /*
2801 * We don't know if p has a earlier or later deadline, so let's blindly
2802 * set a (maybe not needed) rescheduling point.
2803 */
2804 resched_curr(rq);
2805#endif
2806}
2807
2808#ifdef CONFIG_SCHED_CORE
2809static int task_is_throttled_dl(struct task_struct *p, int cpu)
2810{
2811 return p->dl.dl_throttled;
2812}
2813#endif
2814
2815DEFINE_SCHED_CLASS(dl) = {
2816
2817 .enqueue_task = enqueue_task_dl,
2818 .dequeue_task = dequeue_task_dl,
2819 .yield_task = yield_task_dl,
2820
2821 .wakeup_preempt = wakeup_preempt_dl,
2822
2823 .pick_next_task = pick_next_task_dl,
2824 .put_prev_task = put_prev_task_dl,
2825 .set_next_task = set_next_task_dl,
2826
2827#ifdef CONFIG_SMP
2828 .balance = balance_dl,
2829 .pick_task = pick_task_dl,
2830 .select_task_rq = select_task_rq_dl,
2831 .migrate_task_rq = migrate_task_rq_dl,
2832 .set_cpus_allowed = set_cpus_allowed_dl,
2833 .rq_online = rq_online_dl,
2834 .rq_offline = rq_offline_dl,
2835 .task_woken = task_woken_dl,
2836 .find_lock_rq = find_lock_later_rq,
2837#endif
2838
2839 .task_tick = task_tick_dl,
2840 .task_fork = task_fork_dl,
2841
2842 .prio_changed = prio_changed_dl,
2843 .switched_from = switched_from_dl,
2844 .switched_to = switched_to_dl,
2845
2846 .update_curr = update_curr_dl,
2847#ifdef CONFIG_SCHED_CORE
2848 .task_is_throttled = task_is_throttled_dl,
2849#endif
2850};
2851
2852/* Used for dl_bw check and update, used under sched_rt_handler()::mutex */
2853static u64 dl_generation;
2854
2855int sched_dl_global_validate(void)
2856{
2857 u64 runtime = global_rt_runtime();
2858 u64 period = global_rt_period();
2859 u64 new_bw = to_ratio(period, runtime);
2860 u64 gen = ++dl_generation;
2861 struct dl_bw *dl_b;
2862 int cpu, cpus, ret = 0;
2863 unsigned long flags;
2864
2865 /*
2866 * Here we want to check the bandwidth not being set to some
2867 * value smaller than the currently allocated bandwidth in
2868 * any of the root_domains.
2869 */
2870 for_each_possible_cpu(cpu) {
2871 rcu_read_lock_sched();
2872
2873 if (dl_bw_visited(cpu, gen))
2874 goto next;
2875
2876 dl_b = dl_bw_of(cpu);
2877 cpus = dl_bw_cpus(cpu);
2878
2879 raw_spin_lock_irqsave(&dl_b->lock, flags);
2880 if (new_bw * cpus < dl_b->total_bw)
2881 ret = -EBUSY;
2882 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
2883
2884next:
2885 rcu_read_unlock_sched();
2886
2887 if (ret)
2888 break;
2889 }
2890
2891 return ret;
2892}
2893
2894static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq)
2895{
2896 if (global_rt_runtime() == RUNTIME_INF) {
2897 dl_rq->bw_ratio = 1 << RATIO_SHIFT;
2898 dl_rq->max_bw = dl_rq->extra_bw = 1 << BW_SHIFT;
2899 } else {
2900 dl_rq->bw_ratio = to_ratio(global_rt_runtime(),
2901 global_rt_period()) >> (BW_SHIFT - RATIO_SHIFT);
2902 dl_rq->max_bw = dl_rq->extra_bw =
2903 to_ratio(global_rt_period(), global_rt_runtime());
2904 }
2905}
2906
2907void sched_dl_do_global(void)
2908{
2909 u64 new_bw = -1;
2910 u64 gen = ++dl_generation;
2911 struct dl_bw *dl_b;
2912 int cpu;
2913 unsigned long flags;
2914
2915 if (global_rt_runtime() != RUNTIME_INF)
2916 new_bw = to_ratio(global_rt_period(), global_rt_runtime());
2917
2918 for_each_possible_cpu(cpu) {
2919 rcu_read_lock_sched();
2920
2921 if (dl_bw_visited(cpu, gen)) {
2922 rcu_read_unlock_sched();
2923 continue;
2924 }
2925
2926 dl_b = dl_bw_of(cpu);
2927
2928 raw_spin_lock_irqsave(&dl_b->lock, flags);
2929 dl_b->bw = new_bw;
2930 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
2931
2932 rcu_read_unlock_sched();
2933 init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl);
2934 }
2935}
2936
2937/*
2938 * We must be sure that accepting a new task (or allowing changing the
2939 * parameters of an existing one) is consistent with the bandwidth
2940 * constraints. If yes, this function also accordingly updates the currently
2941 * allocated bandwidth to reflect the new situation.
2942 *
2943 * This function is called while holding p's rq->lock.
2944 */
2945int sched_dl_overflow(struct task_struct *p, int policy,
2946 const struct sched_attr *attr)
2947{
2948 u64 period = attr->sched_period ?: attr->sched_deadline;
2949 u64 runtime = attr->sched_runtime;
2950 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2951 int cpus, err = -1, cpu = task_cpu(p);
2952 struct dl_bw *dl_b = dl_bw_of(cpu);
2953 unsigned long cap;
2954
2955 if (attr->sched_flags & SCHED_FLAG_SUGOV)
2956 return 0;
2957
2958 /* !deadline task may carry old deadline bandwidth */
2959 if (new_bw == p->dl.dl_bw && task_has_dl_policy(p))
2960 return 0;
2961
2962 /*
2963 * Either if a task, enters, leave, or stays -deadline but changes
2964 * its parameters, we may need to update accordingly the total
2965 * allocated bandwidth of the container.
2966 */
2967 raw_spin_lock(&dl_b->lock);
2968 cpus = dl_bw_cpus(cpu);
2969 cap = dl_bw_capacity(cpu);
2970
2971 if (dl_policy(policy) && !task_has_dl_policy(p) &&
2972 !__dl_overflow(dl_b, cap, 0, new_bw)) {
2973 if (hrtimer_active(&p->dl.inactive_timer))
2974 __dl_sub(dl_b, p->dl.dl_bw, cpus);
2975 __dl_add(dl_b, new_bw, cpus);
2976 err = 0;
2977 } else if (dl_policy(policy) && task_has_dl_policy(p) &&
2978 !__dl_overflow(dl_b, cap, p->dl.dl_bw, new_bw)) {
2979 /*
2980 * XXX this is slightly incorrect: when the task
2981 * utilization decreases, we should delay the total
2982 * utilization change until the task's 0-lag point.
2983 * But this would require to set the task's "inactive
2984 * timer" when the task is not inactive.
2985 */
2986 __dl_sub(dl_b, p->dl.dl_bw, cpus);
2987 __dl_add(dl_b, new_bw, cpus);
2988 dl_change_utilization(p, new_bw);
2989 err = 0;
2990 } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2991 /*
2992 * Do not decrease the total deadline utilization here,
2993 * switched_from_dl() will take care to do it at the correct
2994 * (0-lag) time.
2995 */
2996 err = 0;
2997 }
2998 raw_spin_unlock(&dl_b->lock);
2999
3000 return err;
3001}
3002
3003/*
3004 * This function initializes the sched_dl_entity of a newly becoming
3005 * SCHED_DEADLINE task.
3006 *
3007 * Only the static values are considered here, the actual runtime and the
3008 * absolute deadline will be properly calculated when the task is enqueued
3009 * for the first time with its new policy.
3010 */
3011void __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3012{
3013 struct sched_dl_entity *dl_se = &p->dl;
3014
3015 dl_se->dl_runtime = attr->sched_runtime;
3016 dl_se->dl_deadline = attr->sched_deadline;
3017 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3018 dl_se->flags = attr->sched_flags & SCHED_DL_FLAGS;
3019 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3020 dl_se->dl_density = to_ratio(dl_se->dl_deadline, dl_se->dl_runtime);
3021}
3022
3023void __getparam_dl(struct task_struct *p, struct sched_attr *attr)
3024{
3025 struct sched_dl_entity *dl_se = &p->dl;
3026
3027 attr->sched_priority = p->rt_priority;
3028 attr->sched_runtime = dl_se->dl_runtime;
3029 attr->sched_deadline = dl_se->dl_deadline;
3030 attr->sched_period = dl_se->dl_period;
3031 attr->sched_flags &= ~SCHED_DL_FLAGS;
3032 attr->sched_flags |= dl_se->flags;
3033}
3034
3035/*
3036 * This function validates the new parameters of a -deadline task.
3037 * We ask for the deadline not being zero, and greater or equal
3038 * than the runtime, as well as the period of being zero or
3039 * greater than deadline. Furthermore, we have to be sure that
3040 * user parameters are above the internal resolution of 1us (we
3041 * check sched_runtime only since it is always the smaller one) and
3042 * below 2^63 ns (we have to check both sched_deadline and
3043 * sched_period, as the latter can be zero).
3044 */
3045bool __checkparam_dl(const struct sched_attr *attr)
3046{
3047 u64 period, max, min;
3048
3049 /* special dl tasks don't actually use any parameter */
3050 if (attr->sched_flags & SCHED_FLAG_SUGOV)
3051 return true;
3052
3053 /* deadline != 0 */
3054 if (attr->sched_deadline == 0)
3055 return false;
3056
3057 /*
3058 * Since we truncate DL_SCALE bits, make sure we're at least
3059 * that big.
3060 */
3061 if (attr->sched_runtime < (1ULL << DL_SCALE))
3062 return false;
3063
3064 /*
3065 * Since we use the MSB for wrap-around and sign issues, make
3066 * sure it's not set (mind that period can be equal to zero).
3067 */
3068 if (attr->sched_deadline & (1ULL << 63) ||
3069 attr->sched_period & (1ULL << 63))
3070 return false;
3071
3072 period = attr->sched_period;
3073 if (!period)
3074 period = attr->sched_deadline;
3075
3076 /* runtime <= deadline <= period (if period != 0) */
3077 if (period < attr->sched_deadline ||
3078 attr->sched_deadline < attr->sched_runtime)
3079 return false;
3080
3081 max = (u64)READ_ONCE(sysctl_sched_dl_period_max) * NSEC_PER_USEC;
3082 min = (u64)READ_ONCE(sysctl_sched_dl_period_min) * NSEC_PER_USEC;
3083
3084 if (period < min || period > max)
3085 return false;
3086
3087 return true;
3088}
3089
3090/*
3091 * This function clears the sched_dl_entity static params.
3092 */
3093static void __dl_clear_params(struct sched_dl_entity *dl_se)
3094{
3095 dl_se->dl_runtime = 0;
3096 dl_se->dl_deadline = 0;
3097 dl_se->dl_period = 0;
3098 dl_se->flags = 0;
3099 dl_se->dl_bw = 0;
3100 dl_se->dl_density = 0;
3101
3102 dl_se->dl_throttled = 0;
3103 dl_se->dl_yielded = 0;
3104 dl_se->dl_non_contending = 0;
3105 dl_se->dl_overrun = 0;
3106 dl_se->dl_server = 0;
3107
3108#ifdef CONFIG_RT_MUTEXES
3109 dl_se->pi_se = dl_se;
3110#endif
3111}
3112
3113void init_dl_entity(struct sched_dl_entity *dl_se)
3114{
3115 RB_CLEAR_NODE(&dl_se->rb_node);
3116 init_dl_task_timer(dl_se);
3117 init_dl_inactive_task_timer(dl_se);
3118 __dl_clear_params(dl_se);
3119}
3120
3121bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
3122{
3123 struct sched_dl_entity *dl_se = &p->dl;
3124
3125 if (dl_se->dl_runtime != attr->sched_runtime ||
3126 dl_se->dl_deadline != attr->sched_deadline ||
3127 dl_se->dl_period != attr->sched_period ||
3128 dl_se->flags != (attr->sched_flags & SCHED_DL_FLAGS))
3129 return true;
3130
3131 return false;
3132}
3133
3134#ifdef CONFIG_SMP
3135int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
3136 const struct cpumask *trial)
3137{
3138 unsigned long flags, cap;
3139 struct dl_bw *cur_dl_b;
3140 int ret = 1;
3141
3142 rcu_read_lock_sched();
3143 cur_dl_b = dl_bw_of(cpumask_any(cur));
3144 cap = __dl_bw_capacity(trial);
3145 raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
3146 if (__dl_overflow(cur_dl_b, cap, 0, 0))
3147 ret = 0;
3148 raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
3149 rcu_read_unlock_sched();
3150
3151 return ret;
3152}
3153
3154enum dl_bw_request {
3155 dl_bw_req_check_overflow = 0,
3156 dl_bw_req_alloc,
3157 dl_bw_req_free
3158};
3159
3160static int dl_bw_manage(enum dl_bw_request req, int cpu, u64 dl_bw)
3161{
3162 unsigned long flags;
3163 struct dl_bw *dl_b;
3164 bool overflow = 0;
3165
3166 rcu_read_lock_sched();
3167 dl_b = dl_bw_of(cpu);
3168 raw_spin_lock_irqsave(&dl_b->lock, flags);
3169
3170 if (req == dl_bw_req_free) {
3171 __dl_sub(dl_b, dl_bw, dl_bw_cpus(cpu));
3172 } else {
3173 unsigned long cap = dl_bw_capacity(cpu);
3174
3175 overflow = __dl_overflow(dl_b, cap, 0, dl_bw);
3176
3177 if (req == dl_bw_req_alloc && !overflow) {
3178 /*
3179 * We reserve space in the destination
3180 * root_domain, as we can't fail after this point.
3181 * We will free resources in the source root_domain
3182 * later on (see set_cpus_allowed_dl()).
3183 */
3184 __dl_add(dl_b, dl_bw, dl_bw_cpus(cpu));
3185 }
3186 }
3187
3188 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
3189 rcu_read_unlock_sched();
3190
3191 return overflow ? -EBUSY : 0;
3192}
3193
3194int dl_bw_check_overflow(int cpu)
3195{
3196 return dl_bw_manage(dl_bw_req_check_overflow, cpu, 0);
3197}
3198
3199int dl_bw_alloc(int cpu, u64 dl_bw)
3200{
3201 return dl_bw_manage(dl_bw_req_alloc, cpu, dl_bw);
3202}
3203
3204void dl_bw_free(int cpu, u64 dl_bw)
3205{
3206 dl_bw_manage(dl_bw_req_free, cpu, dl_bw);
3207}
3208#endif
3209
3210#ifdef CONFIG_SCHED_DEBUG
3211void print_dl_stats(struct seq_file *m, int cpu)
3212{
3213 print_dl_rq(m, cpu, &cpu_rq(cpu)->dl);
3214}
3215#endif /* CONFIG_SCHED_DEBUG */