1 // SPDX-License-Identifier: GPL-2.0
3 * Deadline Scheduling Class (SCHED_DEADLINE)
5 * Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS).
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.
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>
21 struct dl_bandwidth def_dl_bandwidth
;
23 static inline struct task_struct
*dl_task_of(struct sched_dl_entity
*dl_se
)
25 return container_of(dl_se
, struct task_struct
, dl
);
28 static inline struct rq
*rq_of_dl_rq(struct dl_rq
*dl_rq
)
30 return container_of(dl_rq
, struct rq
, dl
);
33 static inline struct dl_rq
*dl_rq_of_se(struct sched_dl_entity
*dl_se
)
35 struct task_struct
*p
= dl_task_of(dl_se
);
36 struct rq
*rq
= task_rq(p
);
41 static inline int on_dl_rq(struct sched_dl_entity
*dl_se
)
43 return !RB_EMPTY_NODE(&dl_se
->rb_node
);
47 static inline struct dl_bw
*dl_bw_of(int i
)
49 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
50 "sched RCU must be held");
51 return &cpu_rq(i
)->rd
->dl_bw
;
54 static inline int dl_bw_cpus(int i
)
56 struct root_domain
*rd
= cpu_rq(i
)->rd
;
59 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
60 "sched RCU must be held");
61 for_each_cpu_and(i
, rd
->span
, cpu_active_mask
)
67 static inline struct dl_bw
*dl_bw_of(int i
)
69 return &cpu_rq(i
)->dl
.dl_bw
;
72 static inline int dl_bw_cpus(int i
)
79 void __add_running_bw(u64 dl_bw
, struct dl_rq
*dl_rq
)
81 u64 old
= dl_rq
->running_bw
;
83 lockdep_assert_held(&(rq_of_dl_rq(dl_rq
))->lock
);
84 dl_rq
->running_bw
+= dl_bw
;
85 SCHED_WARN_ON(dl_rq
->running_bw
< old
); /* overflow */
86 SCHED_WARN_ON(dl_rq
->running_bw
> dl_rq
->this_bw
);
87 /* kick cpufreq (see the comment in kernel/sched/sched.h). */
88 cpufreq_update_util(rq_of_dl_rq(dl_rq
), 0);
92 void __sub_running_bw(u64 dl_bw
, struct dl_rq
*dl_rq
)
94 u64 old
= dl_rq
->running_bw
;
96 lockdep_assert_held(&(rq_of_dl_rq(dl_rq
))->lock
);
97 dl_rq
->running_bw
-= dl_bw
;
98 SCHED_WARN_ON(dl_rq
->running_bw
> old
); /* underflow */
99 if (dl_rq
->running_bw
> old
)
100 dl_rq
->running_bw
= 0;
101 /* kick cpufreq (see the comment in kernel/sched/sched.h). */
102 cpufreq_update_util(rq_of_dl_rq(dl_rq
), 0);
106 void __add_rq_bw(u64 dl_bw
, struct dl_rq
*dl_rq
)
108 u64 old
= dl_rq
->this_bw
;
110 lockdep_assert_held(&(rq_of_dl_rq(dl_rq
))->lock
);
111 dl_rq
->this_bw
+= dl_bw
;
112 SCHED_WARN_ON(dl_rq
->this_bw
< old
); /* overflow */
116 void __sub_rq_bw(u64 dl_bw
, struct dl_rq
*dl_rq
)
118 u64 old
= dl_rq
->this_bw
;
120 lockdep_assert_held(&(rq_of_dl_rq(dl_rq
))->lock
);
121 dl_rq
->this_bw
-= dl_bw
;
122 SCHED_WARN_ON(dl_rq
->this_bw
> old
); /* underflow */
123 if (dl_rq
->this_bw
> old
)
125 SCHED_WARN_ON(dl_rq
->running_bw
> dl_rq
->this_bw
);
129 void add_rq_bw(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
131 if (!dl_entity_is_special(dl_se
))
132 __add_rq_bw(dl_se
->dl_bw
, dl_rq
);
136 void sub_rq_bw(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
138 if (!dl_entity_is_special(dl_se
))
139 __sub_rq_bw(dl_se
->dl_bw
, dl_rq
);
143 void add_running_bw(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
145 if (!dl_entity_is_special(dl_se
))
146 __add_running_bw(dl_se
->dl_bw
, dl_rq
);
150 void sub_running_bw(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
152 if (!dl_entity_is_special(dl_se
))
153 __sub_running_bw(dl_se
->dl_bw
, dl_rq
);
156 void dl_change_utilization(struct task_struct
*p
, u64 new_bw
)
160 BUG_ON(p
->dl
.flags
& SCHED_FLAG_SUGOV
);
162 if (task_on_rq_queued(p
))
166 if (p
->dl
.dl_non_contending
) {
167 sub_running_bw(&p
->dl
, &rq
->dl
);
168 p
->dl
.dl_non_contending
= 0;
170 * If the timer handler is currently running and the
171 * timer cannot be cancelled, inactive_task_timer()
172 * will see that dl_not_contending is not set, and
173 * will not touch the rq's active utilization,
174 * so we are still safe.
176 if (hrtimer_try_to_cancel(&p
->dl
.inactive_timer
) == 1)
179 __sub_rq_bw(p
->dl
.dl_bw
, &rq
->dl
);
180 __add_rq_bw(new_bw
, &rq
->dl
);
184 * The utilization of a task cannot be immediately removed from
185 * the rq active utilization (running_bw) when the task blocks.
186 * Instead, we have to wait for the so called "0-lag time".
188 * If a task blocks before the "0-lag time", a timer (the inactive
189 * timer) is armed, and running_bw is decreased when the timer
192 * If the task wakes up again before the inactive timer fires,
193 * the timer is cancelled, whereas if the task wakes up after the
194 * inactive timer fired (and running_bw has been decreased) the
195 * task's utilization has to be added to running_bw again.
196 * A flag in the deadline scheduling entity (dl_non_contending)
197 * is used to avoid race conditions between the inactive timer handler
200 * The following diagram shows how running_bw is updated. A task is
201 * "ACTIVE" when its utilization contributes to running_bw; an
202 * "ACTIVE contending" task is in the TASK_RUNNING state, while an
203 * "ACTIVE non contending" task is a blocked task for which the "0-lag time"
204 * has not passed yet. An "INACTIVE" task is a task for which the "0-lag"
205 * time already passed, which does not contribute to running_bw anymore.
206 * +------------------+
208 * +------------------>+ contending |
209 * | add_running_bw | |
210 * | +----+------+------+
213 * +--------+-------+ | |
214 * | | t >= 0-lag | | wakeup
215 * | INACTIVE |<---------------+ |
216 * | | sub_running_bw | |
217 * +--------+-------+ | |
222 * | +----+------+------+
223 * | sub_running_bw | ACTIVE |
224 * +-------------------+ |
225 * inactive timer | non contending |
226 * fired +------------------+
228 * The task_non_contending() function is invoked when a task
229 * blocks, and checks if the 0-lag time already passed or
230 * not (in the first case, it directly updates running_bw;
231 * in the second case, it arms the inactive timer).
233 * The task_contending() function is invoked when a task wakes
234 * up, and checks if the task is still in the "ACTIVE non contending"
235 * state or not (in the second case, it updates running_bw).
237 static void task_non_contending(struct task_struct
*p
)
239 struct sched_dl_entity
*dl_se
= &p
->dl
;
240 struct hrtimer
*timer
= &dl_se
->inactive_timer
;
241 struct dl_rq
*dl_rq
= dl_rq_of_se(dl_se
);
242 struct rq
*rq
= rq_of_dl_rq(dl_rq
);
246 * If this is a non-deadline task that has been boosted,
249 if (dl_se
->dl_runtime
== 0)
252 if (dl_entity_is_special(dl_se
))
255 WARN_ON(dl_se
->dl_non_contending
);
257 zerolag_time
= dl_se
->deadline
-
258 div64_long((dl_se
->runtime
* dl_se
->dl_period
),
262 * Using relative times instead of the absolute "0-lag time"
263 * allows to simplify the code
265 zerolag_time
-= rq_clock(rq
);
268 * If the "0-lag time" already passed, decrease the active
269 * utilization now, instead of starting a timer
271 if ((zerolag_time
< 0) || hrtimer_active(&dl_se
->inactive_timer
)) {
273 sub_running_bw(dl_se
, dl_rq
);
274 if (!dl_task(p
) || p
->state
== TASK_DEAD
) {
275 struct dl_bw
*dl_b
= dl_bw_of(task_cpu(p
));
277 if (p
->state
== TASK_DEAD
)
278 sub_rq_bw(&p
->dl
, &rq
->dl
);
279 raw_spin_lock(&dl_b
->lock
);
280 __dl_sub(dl_b
, p
->dl
.dl_bw
, dl_bw_cpus(task_cpu(p
)));
281 __dl_clear_params(p
);
282 raw_spin_unlock(&dl_b
->lock
);
288 dl_se
->dl_non_contending
= 1;
290 hrtimer_start(timer
, ns_to_ktime(zerolag_time
), HRTIMER_MODE_REL
);
293 static void task_contending(struct sched_dl_entity
*dl_se
, int flags
)
295 struct dl_rq
*dl_rq
= dl_rq_of_se(dl_se
);
298 * If this is a non-deadline task that has been boosted,
301 if (dl_se
->dl_runtime
== 0)
304 if (flags
& ENQUEUE_MIGRATED
)
305 add_rq_bw(dl_se
, dl_rq
);
307 if (dl_se
->dl_non_contending
) {
308 dl_se
->dl_non_contending
= 0;
310 * If the timer handler is currently running and the
311 * timer cannot be cancelled, inactive_task_timer()
312 * will see that dl_not_contending is not set, and
313 * will not touch the rq's active utilization,
314 * so we are still safe.
316 if (hrtimer_try_to_cancel(&dl_se
->inactive_timer
) == 1)
317 put_task_struct(dl_task_of(dl_se
));
320 * Since "dl_non_contending" is not set, the
321 * task's utilization has already been removed from
322 * active utilization (either when the task blocked,
323 * when the "inactive timer" fired).
326 add_running_bw(dl_se
, dl_rq
);
330 static inline int is_leftmost(struct task_struct
*p
, struct dl_rq
*dl_rq
)
332 struct sched_dl_entity
*dl_se
= &p
->dl
;
334 return dl_rq
->root
.rb_leftmost
== &dl_se
->rb_node
;
337 void init_dl_bandwidth(struct dl_bandwidth
*dl_b
, u64 period
, u64 runtime
)
339 raw_spin_lock_init(&dl_b
->dl_runtime_lock
);
340 dl_b
->dl_period
= period
;
341 dl_b
->dl_runtime
= runtime
;
344 void init_dl_bw(struct dl_bw
*dl_b
)
346 raw_spin_lock_init(&dl_b
->lock
);
347 raw_spin_lock(&def_dl_bandwidth
.dl_runtime_lock
);
348 if (global_rt_runtime() == RUNTIME_INF
)
351 dl_b
->bw
= to_ratio(global_rt_period(), global_rt_runtime());
352 raw_spin_unlock(&def_dl_bandwidth
.dl_runtime_lock
);
356 void init_dl_rq(struct dl_rq
*dl_rq
)
358 dl_rq
->root
= RB_ROOT_CACHED
;
361 /* zero means no -deadline tasks */
362 dl_rq
->earliest_dl
.curr
= dl_rq
->earliest_dl
.next
= 0;
364 dl_rq
->dl_nr_migratory
= 0;
365 dl_rq
->overloaded
= 0;
366 dl_rq
->pushable_dl_tasks_root
= RB_ROOT_CACHED
;
368 init_dl_bw(&dl_rq
->dl_bw
);
371 dl_rq
->running_bw
= 0;
373 init_dl_rq_bw_ratio(dl_rq
);
378 static inline int dl_overloaded(struct rq
*rq
)
380 return atomic_read(&rq
->rd
->dlo_count
);
383 static inline void dl_set_overload(struct rq
*rq
)
388 cpumask_set_cpu(rq
->cpu
, rq
->rd
->dlo_mask
);
390 * Must be visible before the overload count is
391 * set (as in sched_rt.c).
393 * Matched by the barrier in pull_dl_task().
396 atomic_inc(&rq
->rd
->dlo_count
);
399 static inline void dl_clear_overload(struct rq
*rq
)
404 atomic_dec(&rq
->rd
->dlo_count
);
405 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->dlo_mask
);
408 static void update_dl_migration(struct dl_rq
*dl_rq
)
410 if (dl_rq
->dl_nr_migratory
&& dl_rq
->dl_nr_running
> 1) {
411 if (!dl_rq
->overloaded
) {
412 dl_set_overload(rq_of_dl_rq(dl_rq
));
413 dl_rq
->overloaded
= 1;
415 } else if (dl_rq
->overloaded
) {
416 dl_clear_overload(rq_of_dl_rq(dl_rq
));
417 dl_rq
->overloaded
= 0;
421 static void inc_dl_migration(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
423 struct task_struct
*p
= dl_task_of(dl_se
);
425 if (p
->nr_cpus_allowed
> 1)
426 dl_rq
->dl_nr_migratory
++;
428 update_dl_migration(dl_rq
);
431 static void dec_dl_migration(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
433 struct task_struct
*p
= dl_task_of(dl_se
);
435 if (p
->nr_cpus_allowed
> 1)
436 dl_rq
->dl_nr_migratory
--;
438 update_dl_migration(dl_rq
);
442 * The list of pushable -deadline task is not a plist, like in
443 * sched_rt.c, it is an rb-tree with tasks ordered by deadline.
445 static void enqueue_pushable_dl_task(struct rq
*rq
, struct task_struct
*p
)
447 struct dl_rq
*dl_rq
= &rq
->dl
;
448 struct rb_node
**link
= &dl_rq
->pushable_dl_tasks_root
.rb_root
.rb_node
;
449 struct rb_node
*parent
= NULL
;
450 struct task_struct
*entry
;
451 bool leftmost
= true;
453 BUG_ON(!RB_EMPTY_NODE(&p
->pushable_dl_tasks
));
457 entry
= rb_entry(parent
, struct task_struct
,
459 if (dl_entity_preempt(&p
->dl
, &entry
->dl
))
460 link
= &parent
->rb_left
;
462 link
= &parent
->rb_right
;
468 dl_rq
->earliest_dl
.next
= p
->dl
.deadline
;
470 rb_link_node(&p
->pushable_dl_tasks
, parent
, link
);
471 rb_insert_color_cached(&p
->pushable_dl_tasks
,
472 &dl_rq
->pushable_dl_tasks_root
, leftmost
);
475 static void dequeue_pushable_dl_task(struct rq
*rq
, struct task_struct
*p
)
477 struct dl_rq
*dl_rq
= &rq
->dl
;
479 if (RB_EMPTY_NODE(&p
->pushable_dl_tasks
))
482 if (dl_rq
->pushable_dl_tasks_root
.rb_leftmost
== &p
->pushable_dl_tasks
) {
483 struct rb_node
*next_node
;
485 next_node
= rb_next(&p
->pushable_dl_tasks
);
487 dl_rq
->earliest_dl
.next
= rb_entry(next_node
,
488 struct task_struct
, pushable_dl_tasks
)->dl
.deadline
;
492 rb_erase_cached(&p
->pushable_dl_tasks
, &dl_rq
->pushable_dl_tasks_root
);
493 RB_CLEAR_NODE(&p
->pushable_dl_tasks
);
496 static inline int has_pushable_dl_tasks(struct rq
*rq
)
498 return !RB_EMPTY_ROOT(&rq
->dl
.pushable_dl_tasks_root
.rb_root
);
501 static int push_dl_task(struct rq
*rq
);
503 static inline bool need_pull_dl_task(struct rq
*rq
, struct task_struct
*prev
)
505 return dl_task(prev
);
508 static DEFINE_PER_CPU(struct callback_head
, dl_push_head
);
509 static DEFINE_PER_CPU(struct callback_head
, dl_pull_head
);
511 static void push_dl_tasks(struct rq
*);
512 static void pull_dl_task(struct rq
*);
514 static inline void deadline_queue_push_tasks(struct rq
*rq
)
516 if (!has_pushable_dl_tasks(rq
))
519 queue_balance_callback(rq
, &per_cpu(dl_push_head
, rq
->cpu
), push_dl_tasks
);
522 static inline void deadline_queue_pull_task(struct rq
*rq
)
524 queue_balance_callback(rq
, &per_cpu(dl_pull_head
, rq
->cpu
), pull_dl_task
);
527 static struct rq
*find_lock_later_rq(struct task_struct
*task
, struct rq
*rq
);
529 static struct rq
*dl_task_offline_migration(struct rq
*rq
, struct task_struct
*p
)
531 struct rq
*later_rq
= NULL
;
533 later_rq
= find_lock_later_rq(p
, rq
);
538 * If we cannot preempt any rq, fall back to pick any
541 cpu
= cpumask_any_and(cpu_active_mask
, p
->cpus_ptr
);
542 if (cpu
>= nr_cpu_ids
) {
544 * Failed to find any suitable CPU.
545 * The task will never come back!
547 BUG_ON(dl_bandwidth_enabled());
550 * If admission control is disabled we
551 * try a little harder to let the task
554 cpu
= cpumask_any(cpu_active_mask
);
556 later_rq
= cpu_rq(cpu
);
557 double_lock_balance(rq
, later_rq
);
560 set_task_cpu(p
, later_rq
->cpu
);
561 double_unlock_balance(later_rq
, rq
);
569 void enqueue_pushable_dl_task(struct rq
*rq
, struct task_struct
*p
)
574 void dequeue_pushable_dl_task(struct rq
*rq
, struct task_struct
*p
)
579 void inc_dl_migration(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
584 void dec_dl_migration(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
588 static inline bool need_pull_dl_task(struct rq
*rq
, struct task_struct
*prev
)
593 static inline void pull_dl_task(struct rq
*rq
)
597 static inline void deadline_queue_push_tasks(struct rq
*rq
)
601 static inline void deadline_queue_pull_task(struct rq
*rq
)
604 #endif /* CONFIG_SMP */
606 static void enqueue_task_dl(struct rq
*rq
, struct task_struct
*p
, int flags
);
607 static void __dequeue_task_dl(struct rq
*rq
, struct task_struct
*p
, int flags
);
608 static void check_preempt_curr_dl(struct rq
*rq
, struct task_struct
*p
, int flags
);
611 * We are being explicitly informed that a new instance is starting,
612 * and this means that:
613 * - the absolute deadline of the entity has to be placed at
614 * current time + relative deadline;
615 * - the runtime of the entity has to be set to the maximum value.
617 * The capability of specifying such event is useful whenever a -deadline
618 * entity wants to (try to!) synchronize its behaviour with the scheduler's
619 * one, and to (try to!) reconcile itself with its own scheduling
622 static inline void setup_new_dl_entity(struct sched_dl_entity
*dl_se
)
624 struct dl_rq
*dl_rq
= dl_rq_of_se(dl_se
);
625 struct rq
*rq
= rq_of_dl_rq(dl_rq
);
627 WARN_ON(dl_se
->dl_boosted
);
628 WARN_ON(dl_time_before(rq_clock(rq
), dl_se
->deadline
));
631 * We are racing with the deadline timer. So, do nothing because
632 * the deadline timer handler will take care of properly recharging
633 * the runtime and postponing the deadline
635 if (dl_se
->dl_throttled
)
639 * We use the regular wall clock time to set deadlines in the
640 * future; in fact, we must consider execution overheads (time
641 * spent on hardirq context, etc.).
643 dl_se
->deadline
= rq_clock(rq
) + dl_se
->dl_deadline
;
644 dl_se
->runtime
= dl_se
->dl_runtime
;
648 * Pure Earliest Deadline First (EDF) scheduling does not deal with the
649 * possibility of a entity lasting more than what it declared, and thus
650 * exhausting its runtime.
652 * Here we are interested in making runtime overrun possible, but we do
653 * not want a entity which is misbehaving to affect the scheduling of all
655 * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
656 * is used, in order to confine each entity within its own bandwidth.
658 * This function deals exactly with that, and ensures that when the runtime
659 * of a entity is replenished, its deadline is also postponed. That ensures
660 * the overrunning entity can't interfere with other entity in the system and
661 * can't make them miss their deadlines. Reasons why this kind of overruns
662 * could happen are, typically, a entity voluntarily trying to overcome its
663 * runtime, or it just underestimated it during sched_setattr().
665 static void replenish_dl_entity(struct sched_dl_entity
*dl_se
,
666 struct sched_dl_entity
*pi_se
)
668 struct dl_rq
*dl_rq
= dl_rq_of_se(dl_se
);
669 struct rq
*rq
= rq_of_dl_rq(dl_rq
);
671 BUG_ON(pi_se
->dl_runtime
<= 0);
674 * This could be the case for a !-dl task that is boosted.
675 * Just go with full inherited parameters.
677 if (dl_se
->dl_deadline
== 0) {
678 dl_se
->deadline
= rq_clock(rq
) + pi_se
->dl_deadline
;
679 dl_se
->runtime
= pi_se
->dl_runtime
;
682 if (dl_se
->dl_yielded
&& dl_se
->runtime
> 0)
686 * We keep moving the deadline away until we get some
687 * available runtime for the entity. This ensures correct
688 * handling of situations where the runtime overrun is
691 while (dl_se
->runtime
<= 0) {
692 dl_se
->deadline
+= pi_se
->dl_period
;
693 dl_se
->runtime
+= pi_se
->dl_runtime
;
697 * At this point, the deadline really should be "in
698 * the future" with respect to rq->clock. If it's
699 * not, we are, for some reason, lagging too much!
700 * Anyway, after having warn userspace abut that,
701 * we still try to keep the things running by
702 * resetting the deadline and the budget of the
705 if (dl_time_before(dl_se
->deadline
, rq_clock(rq
))) {
706 printk_deferred_once("sched: DL replenish lagged too much\n");
707 dl_se
->deadline
= rq_clock(rq
) + pi_se
->dl_deadline
;
708 dl_se
->runtime
= pi_se
->dl_runtime
;
711 if (dl_se
->dl_yielded
)
712 dl_se
->dl_yielded
= 0;
713 if (dl_se
->dl_throttled
)
714 dl_se
->dl_throttled
= 0;
718 * Here we check if --at time t-- an entity (which is probably being
719 * [re]activated or, in general, enqueued) can use its remaining runtime
720 * and its current deadline _without_ exceeding the bandwidth it is
721 * assigned (function returns true if it can't). We are in fact applying
722 * one of the CBS rules: when a task wakes up, if the residual runtime
723 * over residual deadline fits within the allocated bandwidth, then we
724 * can keep the current (absolute) deadline and residual budget without
725 * disrupting the schedulability of the system. Otherwise, we should
726 * refill the runtime and set the deadline a period in the future,
727 * because keeping the current (absolute) deadline of the task would
728 * result in breaking guarantees promised to other tasks (refer to
729 * Documentation/scheduler/sched-deadline.rst for more information).
731 * This function returns true if:
733 * runtime / (deadline - t) > dl_runtime / dl_deadline ,
735 * IOW we can't recycle current parameters.
737 * Notice that the bandwidth check is done against the deadline. For
738 * task with deadline equal to period this is the same of using
739 * dl_period instead of dl_deadline in the equation above.
741 static bool dl_entity_overflow(struct sched_dl_entity
*dl_se
,
742 struct sched_dl_entity
*pi_se
, u64 t
)
747 * left and right are the two sides of the equation above,
748 * after a bit of shuffling to use multiplications instead
751 * Note that none of the time values involved in the two
752 * multiplications are absolute: dl_deadline and dl_runtime
753 * are the relative deadline and the maximum runtime of each
754 * instance, runtime is the runtime left for the last instance
755 * and (deadline - t), since t is rq->clock, is the time left
756 * to the (absolute) deadline. Even if overflowing the u64 type
757 * is very unlikely to occur in both cases, here we scale down
758 * as we want to avoid that risk at all. Scaling down by 10
759 * means that we reduce granularity to 1us. We are fine with it,
760 * since this is only a true/false check and, anyway, thinking
761 * of anything below microseconds resolution is actually fiction
762 * (but still we want to give the user that illusion >;).
764 left
= (pi_se
->dl_deadline
>> DL_SCALE
) * (dl_se
->runtime
>> DL_SCALE
);
765 right
= ((dl_se
->deadline
- t
) >> DL_SCALE
) *
766 (pi_se
->dl_runtime
>> DL_SCALE
);
768 return dl_time_before(right
, left
);
772 * Revised wakeup rule [1]: For self-suspending tasks, rather then
773 * re-initializing task's runtime and deadline, the revised wakeup
774 * rule adjusts the task's runtime to avoid the task to overrun its
777 * Reasoning: a task may overrun the density if:
778 * runtime / (deadline - t) > dl_runtime / dl_deadline
780 * Therefore, runtime can be adjusted to:
781 * runtime = (dl_runtime / dl_deadline) * (deadline - t)
783 * In such way that runtime will be equal to the maximum density
784 * the task can use without breaking any rule.
786 * [1] Luca Abeni, Giuseppe Lipari, and Juri Lelli. 2015. Constant
787 * bandwidth server revisited. SIGBED Rev. 11, 4 (January 2015), 19-24.
790 update_dl_revised_wakeup(struct sched_dl_entity
*dl_se
, struct rq
*rq
)
792 u64 laxity
= dl_se
->deadline
- rq_clock(rq
);
795 * If the task has deadline < period, and the deadline is in the past,
796 * it should already be throttled before this check.
798 * See update_dl_entity() comments for further details.
800 WARN_ON(dl_time_before(dl_se
->deadline
, rq_clock(rq
)));
802 dl_se
->runtime
= (dl_se
->dl_density
* laxity
) >> BW_SHIFT
;
806 * Regarding the deadline, a task with implicit deadline has a relative
807 * deadline == relative period. A task with constrained deadline has a
808 * relative deadline <= relative period.
810 * We support constrained deadline tasks. However, there are some restrictions
811 * applied only for tasks which do not have an implicit deadline. See
812 * update_dl_entity() to know more about such restrictions.
814 * The dl_is_implicit() returns true if the task has an implicit deadline.
816 static inline bool dl_is_implicit(struct sched_dl_entity
*dl_se
)
818 return dl_se
->dl_deadline
== dl_se
->dl_period
;
822 * When a deadline entity is placed in the runqueue, its runtime and deadline
823 * might need to be updated. This is done by a CBS wake up rule. There are two
824 * different rules: 1) the original CBS; and 2) the Revisited CBS.
826 * When the task is starting a new period, the Original CBS is used. In this
827 * case, the runtime is replenished and a new absolute deadline is set.
829 * When a task is queued before the begin of the next period, using the
830 * remaining runtime and deadline could make the entity to overflow, see
831 * dl_entity_overflow() to find more about runtime overflow. When such case
832 * is detected, the runtime and deadline need to be updated.
834 * If the task has an implicit deadline, i.e., deadline == period, the Original
835 * CBS is applied. the runtime is replenished and a new absolute deadline is
836 * set, as in the previous cases.
838 * However, the Original CBS does not work properly for tasks with
839 * deadline < period, which are said to have a constrained deadline. By
840 * applying the Original CBS, a constrained deadline task would be able to run
841 * runtime/deadline in a period. With deadline < period, the task would
842 * overrun the runtime/period allowed bandwidth, breaking the admission test.
844 * In order to prevent this misbehave, the Revisited CBS is used for
845 * constrained deadline tasks when a runtime overflow is detected. In the
846 * Revisited CBS, rather than replenishing & setting a new absolute deadline,
847 * the remaining runtime of the task is reduced to avoid runtime overflow.
848 * Please refer to the comments update_dl_revised_wakeup() function to find
849 * more about the Revised CBS rule.
851 static void update_dl_entity(struct sched_dl_entity
*dl_se
,
852 struct sched_dl_entity
*pi_se
)
854 struct dl_rq
*dl_rq
= dl_rq_of_se(dl_se
);
855 struct rq
*rq
= rq_of_dl_rq(dl_rq
);
857 if (dl_time_before(dl_se
->deadline
, rq_clock(rq
)) ||
858 dl_entity_overflow(dl_se
, pi_se
, rq_clock(rq
))) {
860 if (unlikely(!dl_is_implicit(dl_se
) &&
861 !dl_time_before(dl_se
->deadline
, rq_clock(rq
)) &&
862 !dl_se
->dl_boosted
)){
863 update_dl_revised_wakeup(dl_se
, rq
);
867 dl_se
->deadline
= rq_clock(rq
) + pi_se
->dl_deadline
;
868 dl_se
->runtime
= pi_se
->dl_runtime
;
872 static inline u64
dl_next_period(struct sched_dl_entity
*dl_se
)
874 return dl_se
->deadline
- dl_se
->dl_deadline
+ dl_se
->dl_period
;
878 * If the entity depleted all its runtime, and if we want it to sleep
879 * while waiting for some new execution time to become available, we
880 * set the bandwidth replenishment timer to the replenishment instant
881 * and try to activate it.
883 * Notice that it is important for the caller to know if the timer
884 * actually started or not (i.e., the replenishment instant is in
885 * the future or in the past).
887 static int start_dl_timer(struct task_struct
*p
)
889 struct sched_dl_entity
*dl_se
= &p
->dl
;
890 struct hrtimer
*timer
= &dl_se
->dl_timer
;
891 struct rq
*rq
= task_rq(p
);
895 lockdep_assert_held(&rq
->lock
);
898 * We want the timer to fire at the deadline, but considering
899 * that it is actually coming from rq->clock and not from
900 * hrtimer's time base reading.
902 act
= ns_to_ktime(dl_next_period(dl_se
));
903 now
= hrtimer_cb_get_time(timer
);
904 delta
= ktime_to_ns(now
) - rq_clock(rq
);
905 act
= ktime_add_ns(act
, delta
);
908 * If the expiry time already passed, e.g., because the value
909 * chosen as the deadline is too small, don't even try to
910 * start the timer in the past!
912 if (ktime_us_delta(act
, now
) < 0)
916 * !enqueued will guarantee another callback; even if one is already in
917 * progress. This ensures a balanced {get,put}_task_struct().
919 * The race against __run_timer() clearing the enqueued state is
920 * harmless because we're holding task_rq()->lock, therefore the timer
921 * expiring after we've done the check will wait on its task_rq_lock()
922 * and observe our state.
924 if (!hrtimer_is_queued(timer
)) {
926 hrtimer_start(timer
, act
, HRTIMER_MODE_ABS
);
933 * This is the bandwidth enforcement timer callback. If here, we know
934 * a task is not on its dl_rq, since the fact that the timer was running
935 * means the task is throttled and needs a runtime replenishment.
937 * However, what we actually do depends on the fact the task is active,
938 * (it is on its rq) or has been removed from there by a call to
939 * dequeue_task_dl(). In the former case we must issue the runtime
940 * replenishment and add the task back to the dl_rq; in the latter, we just
941 * do nothing but clearing dl_throttled, so that runtime and deadline
942 * updating (and the queueing back to dl_rq) will be done by the
943 * next call to enqueue_task_dl().
945 static enum hrtimer_restart
dl_task_timer(struct hrtimer
*timer
)
947 struct sched_dl_entity
*dl_se
= container_of(timer
,
948 struct sched_dl_entity
,
950 struct task_struct
*p
= dl_task_of(dl_se
);
954 rq
= task_rq_lock(p
, &rf
);
957 * The task might have changed its scheduling policy to something
958 * different than SCHED_DEADLINE (through switched_from_dl()).
964 * The task might have been boosted by someone else and might be in the
965 * boosting/deboosting path, its not throttled.
967 if (dl_se
->dl_boosted
)
971 * Spurious timer due to start_dl_timer() race; or we already received
972 * a replenishment from rt_mutex_setprio().
974 if (!dl_se
->dl_throttled
)
981 * If the throttle happened during sched-out; like:
988 * __dequeue_task_dl()
991 * We can be both throttled and !queued. Replenish the counter
992 * but do not enqueue -- wait for our wakeup to do that.
994 if (!task_on_rq_queued(p
)) {
995 replenish_dl_entity(dl_se
, dl_se
);
1000 if (unlikely(!rq
->online
)) {
1002 * If the runqueue is no longer available, migrate the
1003 * task elsewhere. This necessarily changes rq.
1005 lockdep_unpin_lock(&rq
->lock
, rf
.cookie
);
1006 rq
= dl_task_offline_migration(rq
, p
);
1007 rf
.cookie
= lockdep_pin_lock(&rq
->lock
);
1008 update_rq_clock(rq
);
1011 * Now that the task has been migrated to the new RQ and we
1012 * have that locked, proceed as normal and enqueue the task
1018 enqueue_task_dl(rq
, p
, ENQUEUE_REPLENISH
);
1019 if (dl_task(rq
->curr
))
1020 check_preempt_curr_dl(rq
, p
, 0);
1026 * Queueing this task back might have overloaded rq, check if we need
1027 * to kick someone away.
1029 if (has_pushable_dl_tasks(rq
)) {
1031 * Nothing relies on rq->lock after this, so its safe to drop
1034 rq_unpin_lock(rq
, &rf
);
1036 rq_repin_lock(rq
, &rf
);
1041 task_rq_unlock(rq
, p
, &rf
);
1044 * This can free the task_struct, including this hrtimer, do not touch
1045 * anything related to that after this.
1049 return HRTIMER_NORESTART
;
1052 void init_dl_task_timer(struct sched_dl_entity
*dl_se
)
1054 struct hrtimer
*timer
= &dl_se
->dl_timer
;
1056 hrtimer_init(timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1057 timer
->function
= dl_task_timer
;
1061 * During the activation, CBS checks if it can reuse the current task's
1062 * runtime and period. If the deadline of the task is in the past, CBS
1063 * cannot use the runtime, and so it replenishes the task. This rule
1064 * works fine for implicit deadline tasks (deadline == period), and the
1065 * CBS was designed for implicit deadline tasks. However, a task with
1066 * constrained deadline (deadine < period) might be awakened after the
1067 * deadline, but before the next period. In this case, replenishing the
1068 * task would allow it to run for runtime / deadline. As in this case
1069 * deadline < period, CBS enables a task to run for more than the
1070 * runtime / period. In a very loaded system, this can cause a domino
1071 * effect, making other tasks miss their deadlines.
1073 * To avoid this problem, in the activation of a constrained deadline
1074 * task after the deadline but before the next period, throttle the
1075 * task and set the replenishing timer to the begin of the next period,
1076 * unless it is boosted.
1078 static inline void dl_check_constrained_dl(struct sched_dl_entity
*dl_se
)
1080 struct task_struct
*p
= dl_task_of(dl_se
);
1081 struct rq
*rq
= rq_of_dl_rq(dl_rq_of_se(dl_se
));
1083 if (dl_time_before(dl_se
->deadline
, rq_clock(rq
)) &&
1084 dl_time_before(rq_clock(rq
), dl_next_period(dl_se
))) {
1085 if (unlikely(dl_se
->dl_boosted
|| !start_dl_timer(p
)))
1087 dl_se
->dl_throttled
= 1;
1088 if (dl_se
->runtime
> 0)
1094 int dl_runtime_exceeded(struct sched_dl_entity
*dl_se
)
1096 return (dl_se
->runtime
<= 0);
1099 extern bool sched_rt_bandwidth_account(struct rt_rq
*rt_rq
);
1102 * This function implements the GRUB accounting rule:
1103 * according to the GRUB reclaiming algorithm, the runtime is
1104 * not decreased as "dq = -dt", but as
1105 * "dq = -max{u / Umax, (1 - Uinact - Uextra)} dt",
1106 * where u is the utilization of the task, Umax is the maximum reclaimable
1107 * utilization, Uinact is the (per-runqueue) inactive utilization, computed
1108 * as the difference between the "total runqueue utilization" and the
1109 * runqueue active utilization, and Uextra is the (per runqueue) extra
1110 * reclaimable utilization.
1111 * Since rq->dl.running_bw and rq->dl.this_bw contain utilizations
1112 * multiplied by 2^BW_SHIFT, the result has to be shifted right by
1114 * Since rq->dl.bw_ratio contains 1 / Umax multipled by 2^RATIO_SHIFT,
1115 * dl_bw is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT.
1116 * Since delta is a 64 bit variable, to have an overflow its value
1117 * should be larger than 2^(64 - 20 - 8), which is more than 64 seconds.
1118 * So, overflow is not an issue here.
1120 static u64
grub_reclaim(u64 delta
, struct rq
*rq
, struct sched_dl_entity
*dl_se
)
1122 u64 u_inact
= rq
->dl
.this_bw
- rq
->dl
.running_bw
; /* Utot - Uact */
1124 u64 u_act_min
= (dl_se
->dl_bw
* rq
->dl
.bw_ratio
) >> RATIO_SHIFT
;
1127 * Instead of computing max{u * bw_ratio, (1 - u_inact - u_extra)},
1128 * we compare u_inact + rq->dl.extra_bw with
1129 * 1 - (u * rq->dl.bw_ratio >> RATIO_SHIFT), because
1130 * u_inact + rq->dl.extra_bw can be larger than
1131 * 1 * (so, 1 - u_inact - rq->dl.extra_bw would be negative
1132 * leading to wrong results)
1134 if (u_inact
+ rq
->dl
.extra_bw
> BW_UNIT
- u_act_min
)
1137 u_act
= BW_UNIT
- u_inact
- rq
->dl
.extra_bw
;
1139 return (delta
* u_act
) >> BW_SHIFT
;
1143 * Update the current task's runtime statistics (provided it is still
1144 * a -deadline task and has not been removed from the dl_rq).
1146 static void update_curr_dl(struct rq
*rq
)
1148 struct task_struct
*curr
= rq
->curr
;
1149 struct sched_dl_entity
*dl_se
= &curr
->dl
;
1150 u64 delta_exec
, scaled_delta_exec
;
1151 int cpu
= cpu_of(rq
);
1154 if (!dl_task(curr
) || !on_dl_rq(dl_se
))
1158 * Consumed budget is computed considering the time as
1159 * observed by schedulable tasks (excluding time spent
1160 * in hardirq context, etc.). Deadlines are instead
1161 * computed using hard walltime. This seems to be the more
1162 * natural solution, but the full ramifications of this
1163 * approach need further study.
1165 now
= rq_clock_task(rq
);
1166 delta_exec
= now
- curr
->se
.exec_start
;
1167 if (unlikely((s64
)delta_exec
<= 0)) {
1168 if (unlikely(dl_se
->dl_yielded
))
1173 schedstat_set(curr
->se
.statistics
.exec_max
,
1174 max(curr
->se
.statistics
.exec_max
, delta_exec
));
1176 curr
->se
.sum_exec_runtime
+= delta_exec
;
1177 account_group_exec_runtime(curr
, delta_exec
);
1179 curr
->se
.exec_start
= now
;
1180 cgroup_account_cputime(curr
, delta_exec
);
1182 if (dl_entity_is_special(dl_se
))
1186 * For tasks that participate in GRUB, we implement GRUB-PA: the
1187 * spare reclaimed bandwidth is used to clock down frequency.
1189 * For the others, we still need to scale reservation parameters
1190 * according to current frequency and CPU maximum capacity.
1192 if (unlikely(dl_se
->flags
& SCHED_FLAG_RECLAIM
)) {
1193 scaled_delta_exec
= grub_reclaim(delta_exec
,
1197 unsigned long scale_freq
= arch_scale_freq_capacity(cpu
);
1198 unsigned long scale_cpu
= arch_scale_cpu_capacity(cpu
);
1200 scaled_delta_exec
= cap_scale(delta_exec
, scale_freq
);
1201 scaled_delta_exec
= cap_scale(scaled_delta_exec
, scale_cpu
);
1204 dl_se
->runtime
-= scaled_delta_exec
;
1207 if (dl_runtime_exceeded(dl_se
) || dl_se
->dl_yielded
) {
1208 dl_se
->dl_throttled
= 1;
1210 /* If requested, inform the user about runtime overruns. */
1211 if (dl_runtime_exceeded(dl_se
) &&
1212 (dl_se
->flags
& SCHED_FLAG_DL_OVERRUN
))
1213 dl_se
->dl_overrun
= 1;
1215 __dequeue_task_dl(rq
, curr
, 0);
1216 if (unlikely(dl_se
->dl_boosted
|| !start_dl_timer(curr
)))
1217 enqueue_task_dl(rq
, curr
, ENQUEUE_REPLENISH
);
1219 if (!is_leftmost(curr
, &rq
->dl
))
1224 * Because -- for now -- we share the rt bandwidth, we need to
1225 * account our runtime there too, otherwise actual rt tasks
1226 * would be able to exceed the shared quota.
1228 * Account to the root rt group for now.
1230 * The solution we're working towards is having the RT groups scheduled
1231 * using deadline servers -- however there's a few nasties to figure
1232 * out before that can happen.
1234 if (rt_bandwidth_enabled()) {
1235 struct rt_rq
*rt_rq
= &rq
->rt
;
1237 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
1239 * We'll let actual RT tasks worry about the overflow here, we
1240 * have our own CBS to keep us inline; only account when RT
1241 * bandwidth is relevant.
1243 if (sched_rt_bandwidth_account(rt_rq
))
1244 rt_rq
->rt_time
+= delta_exec
;
1245 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
1249 static enum hrtimer_restart
inactive_task_timer(struct hrtimer
*timer
)
1251 struct sched_dl_entity
*dl_se
= container_of(timer
,
1252 struct sched_dl_entity
,
1254 struct task_struct
*p
= dl_task_of(dl_se
);
1258 rq
= task_rq_lock(p
, &rf
);
1261 update_rq_clock(rq
);
1263 if (!dl_task(p
) || p
->state
== TASK_DEAD
) {
1264 struct dl_bw
*dl_b
= dl_bw_of(task_cpu(p
));
1266 if (p
->state
== TASK_DEAD
&& dl_se
->dl_non_contending
) {
1267 sub_running_bw(&p
->dl
, dl_rq_of_se(&p
->dl
));
1268 sub_rq_bw(&p
->dl
, dl_rq_of_se(&p
->dl
));
1269 dl_se
->dl_non_contending
= 0;
1272 raw_spin_lock(&dl_b
->lock
);
1273 __dl_sub(dl_b
, p
->dl
.dl_bw
, dl_bw_cpus(task_cpu(p
)));
1274 raw_spin_unlock(&dl_b
->lock
);
1275 __dl_clear_params(p
);
1279 if (dl_se
->dl_non_contending
== 0)
1282 sub_running_bw(dl_se
, &rq
->dl
);
1283 dl_se
->dl_non_contending
= 0;
1285 task_rq_unlock(rq
, p
, &rf
);
1288 return HRTIMER_NORESTART
;
1291 void init_dl_inactive_task_timer(struct sched_dl_entity
*dl_se
)
1293 struct hrtimer
*timer
= &dl_se
->inactive_timer
;
1295 hrtimer_init(timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1296 timer
->function
= inactive_task_timer
;
1301 static void inc_dl_deadline(struct dl_rq
*dl_rq
, u64 deadline
)
1303 struct rq
*rq
= rq_of_dl_rq(dl_rq
);
1305 if (dl_rq
->earliest_dl
.curr
== 0 ||
1306 dl_time_before(deadline
, dl_rq
->earliest_dl
.curr
)) {
1307 dl_rq
->earliest_dl
.curr
= deadline
;
1308 cpudl_set(&rq
->rd
->cpudl
, rq
->cpu
, deadline
);
1312 static void dec_dl_deadline(struct dl_rq
*dl_rq
, u64 deadline
)
1314 struct rq
*rq
= rq_of_dl_rq(dl_rq
);
1317 * Since we may have removed our earliest (and/or next earliest)
1318 * task we must recompute them.
1320 if (!dl_rq
->dl_nr_running
) {
1321 dl_rq
->earliest_dl
.curr
= 0;
1322 dl_rq
->earliest_dl
.next
= 0;
1323 cpudl_clear(&rq
->rd
->cpudl
, rq
->cpu
);
1325 struct rb_node
*leftmost
= dl_rq
->root
.rb_leftmost
;
1326 struct sched_dl_entity
*entry
;
1328 entry
= rb_entry(leftmost
, struct sched_dl_entity
, rb_node
);
1329 dl_rq
->earliest_dl
.curr
= entry
->deadline
;
1330 cpudl_set(&rq
->rd
->cpudl
, rq
->cpu
, entry
->deadline
);
1336 static inline void inc_dl_deadline(struct dl_rq
*dl_rq
, u64 deadline
) {}
1337 static inline void dec_dl_deadline(struct dl_rq
*dl_rq
, u64 deadline
) {}
1339 #endif /* CONFIG_SMP */
1342 void inc_dl_tasks(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
1344 int prio
= dl_task_of(dl_se
)->prio
;
1345 u64 deadline
= dl_se
->deadline
;
1347 WARN_ON(!dl_prio(prio
));
1348 dl_rq
->dl_nr_running
++;
1349 add_nr_running(rq_of_dl_rq(dl_rq
), 1);
1351 inc_dl_deadline(dl_rq
, deadline
);
1352 inc_dl_migration(dl_se
, dl_rq
);
1356 void dec_dl_tasks(struct sched_dl_entity
*dl_se
, struct dl_rq
*dl_rq
)
1358 int prio
= dl_task_of(dl_se
)->prio
;
1360 WARN_ON(!dl_prio(prio
));
1361 WARN_ON(!dl_rq
->dl_nr_running
);
1362 dl_rq
->dl_nr_running
--;
1363 sub_nr_running(rq_of_dl_rq(dl_rq
), 1);
1365 dec_dl_deadline(dl_rq
, dl_se
->deadline
);
1366 dec_dl_migration(dl_se
, dl_rq
);
1369 static void __enqueue_dl_entity(struct sched_dl_entity
*dl_se
)
1371 struct dl_rq
*dl_rq
= dl_rq_of_se(dl_se
);
1372 struct rb_node
**link
= &dl_rq
->root
.rb_root
.rb_node
;
1373 struct rb_node
*parent
= NULL
;
1374 struct sched_dl_entity
*entry
;
1377 BUG_ON(!RB_EMPTY_NODE(&dl_se
->rb_node
));
1381 entry
= rb_entry(parent
, struct sched_dl_entity
, rb_node
);
1382 if (dl_time_before(dl_se
->deadline
, entry
->deadline
))
1383 link
= &parent
->rb_left
;
1385 link
= &parent
->rb_right
;
1390 rb_link_node(&dl_se
->rb_node
, parent
, link
);
1391 rb_insert_color_cached(&dl_se
->rb_node
, &dl_rq
->root
, leftmost
);
1393 inc_dl_tasks(dl_se
, dl_rq
);
1396 static void __dequeue_dl_entity(struct sched_dl_entity
*dl_se
)
1398 struct dl_rq
*dl_rq
= dl_rq_of_se(dl_se
);
1400 if (RB_EMPTY_NODE(&dl_se
->rb_node
))
1403 rb_erase_cached(&dl_se
->rb_node
, &dl_rq
->root
);
1404 RB_CLEAR_NODE(&dl_se
->rb_node
);
1406 dec_dl_tasks(dl_se
, dl_rq
);
1410 enqueue_dl_entity(struct sched_dl_entity
*dl_se
,
1411 struct sched_dl_entity
*pi_se
, int flags
)
1413 BUG_ON(on_dl_rq(dl_se
));
1416 * If this is a wakeup or a new instance, the scheduling
1417 * parameters of the task might need updating. Otherwise,
1418 * we want a replenishment of its runtime.
1420 if (flags
& ENQUEUE_WAKEUP
) {
1421 task_contending(dl_se
, flags
);
1422 update_dl_entity(dl_se
, pi_se
);
1423 } else if (flags
& ENQUEUE_REPLENISH
) {
1424 replenish_dl_entity(dl_se
, pi_se
);
1425 } else if ((flags
& ENQUEUE_RESTORE
) &&
1426 dl_time_before(dl_se
->deadline
,
1427 rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se
))))) {
1428 setup_new_dl_entity(dl_se
);
1431 __enqueue_dl_entity(dl_se
);
1434 static void dequeue_dl_entity(struct sched_dl_entity
*dl_se
)
1436 __dequeue_dl_entity(dl_se
);
1439 static void enqueue_task_dl(struct rq
*rq
, struct task_struct
*p
, int flags
)
1441 struct task_struct
*pi_task
= rt_mutex_get_top_task(p
);
1442 struct sched_dl_entity
*pi_se
= &p
->dl
;
1445 * Use the scheduling parameters of the top pi-waiter task if:
1446 * - we have a top pi-waiter which is a SCHED_DEADLINE task AND
1447 * - our dl_boosted is set (i.e. the pi-waiter's (absolute) deadline is
1448 * smaller than our deadline OR we are a !SCHED_DEADLINE task getting
1449 * boosted due to a SCHED_DEADLINE pi-waiter).
1450 * Otherwise we keep our runtime and deadline.
1452 if (pi_task
&& dl_prio(pi_task
->normal_prio
) && p
->dl
.dl_boosted
) {
1453 pi_se
= &pi_task
->dl
;
1454 } else if (!dl_prio(p
->normal_prio
)) {
1456 * Special case in which we have a !SCHED_DEADLINE task
1457 * that is going to be deboosted, but exceeds its
1458 * runtime while doing so. No point in replenishing
1459 * it, as it's going to return back to its original
1460 * scheduling class after this.
1462 BUG_ON(!p
->dl
.dl_boosted
|| flags
!= ENQUEUE_REPLENISH
);
1467 * Check if a constrained deadline task was activated
1468 * after the deadline but before the next period.
1469 * If that is the case, the task will be throttled and
1470 * the replenishment timer will be set to the next period.
1472 if (!p
->dl
.dl_throttled
&& !dl_is_implicit(&p
->dl
))
1473 dl_check_constrained_dl(&p
->dl
);
1475 if (p
->on_rq
== TASK_ON_RQ_MIGRATING
|| flags
& ENQUEUE_RESTORE
) {
1476 add_rq_bw(&p
->dl
, &rq
->dl
);
1477 add_running_bw(&p
->dl
, &rq
->dl
);
1481 * If p is throttled, we do not enqueue it. In fact, if it exhausted
1482 * its budget it needs a replenishment and, since it now is on
1483 * its rq, the bandwidth timer callback (which clearly has not
1484 * run yet) will take care of this.
1485 * However, the active utilization does not depend on the fact
1486 * that the task is on the runqueue or not (but depends on the
1487 * task's state - in GRUB parlance, "inactive" vs "active contending").
1488 * In other words, even if a task is throttled its utilization must
1489 * be counted in the active utilization; hence, we need to call
1492 if (p
->dl
.dl_throttled
&& !(flags
& ENQUEUE_REPLENISH
)) {
1493 if (flags
& ENQUEUE_WAKEUP
)
1494 task_contending(&p
->dl
, flags
);
1499 enqueue_dl_entity(&p
->dl
, pi_se
, flags
);
1501 if (!task_current(rq
, p
) && p
->nr_cpus_allowed
> 1)
1502 enqueue_pushable_dl_task(rq
, p
);
1505 static void __dequeue_task_dl(struct rq
*rq
, struct task_struct
*p
, int flags
)
1507 dequeue_dl_entity(&p
->dl
);
1508 dequeue_pushable_dl_task(rq
, p
);
1511 static void dequeue_task_dl(struct rq
*rq
, struct task_struct
*p
, int flags
)
1514 __dequeue_task_dl(rq
, p
, flags
);
1516 if (p
->on_rq
== TASK_ON_RQ_MIGRATING
|| flags
& DEQUEUE_SAVE
) {
1517 sub_running_bw(&p
->dl
, &rq
->dl
);
1518 sub_rq_bw(&p
->dl
, &rq
->dl
);
1522 * This check allows to start the inactive timer (or to immediately
1523 * decrease the active utilization, if needed) in two cases:
1524 * when the task blocks and when it is terminating
1525 * (p->state == TASK_DEAD). We can handle the two cases in the same
1526 * way, because from GRUB's point of view the same thing is happening
1527 * (the task moves from "active contending" to "active non contending"
1530 if (flags
& DEQUEUE_SLEEP
)
1531 task_non_contending(p
);
1535 * Yield task semantic for -deadline tasks is:
1537 * get off from the CPU until our next instance, with
1538 * a new runtime. This is of little use now, since we
1539 * don't have a bandwidth reclaiming mechanism. Anyway,
1540 * bandwidth reclaiming is planned for the future, and
1541 * yield_task_dl will indicate that some spare budget
1542 * is available for other task instances to use it.
1544 static void yield_task_dl(struct rq
*rq
)
1547 * We make the task go to sleep until its current deadline by
1548 * forcing its runtime to zero. This way, update_curr_dl() stops
1549 * it and the bandwidth timer will wake it up and will give it
1550 * new scheduling parameters (thanks to dl_yielded=1).
1552 rq
->curr
->dl
.dl_yielded
= 1;
1554 update_rq_clock(rq
);
1557 * Tell update_rq_clock() that we've just updated,
1558 * so we don't do microscopic update in schedule()
1559 * and double the fastpath cost.
1561 rq_clock_skip_update(rq
);
1566 static int find_later_rq(struct task_struct
*task
);
1569 select_task_rq_dl(struct task_struct
*p
, int cpu
, int sd_flag
, int flags
)
1571 struct task_struct
*curr
;
1574 if (sd_flag
!= SD_BALANCE_WAKE
)
1580 curr
= READ_ONCE(rq
->curr
); /* unlocked access */
1583 * If we are dealing with a -deadline task, we must
1584 * decide where to wake it up.
1585 * If it has a later deadline and the current task
1586 * on this rq can't move (provided the waking task
1587 * can!) we prefer to send it somewhere else. On the
1588 * other hand, if it has a shorter deadline, we
1589 * try to make it stay here, it might be important.
1591 if (unlikely(dl_task(curr
)) &&
1592 (curr
->nr_cpus_allowed
< 2 ||
1593 !dl_entity_preempt(&p
->dl
, &curr
->dl
)) &&
1594 (p
->nr_cpus_allowed
> 1)) {
1595 int target
= find_later_rq(p
);
1598 (dl_time_before(p
->dl
.deadline
,
1599 cpu_rq(target
)->dl
.earliest_dl
.curr
) ||
1600 (cpu_rq(target
)->dl
.dl_nr_running
== 0)))
1609 static void migrate_task_rq_dl(struct task_struct
*p
, int new_cpu __maybe_unused
)
1613 if (p
->state
!= TASK_WAKING
)
1618 * Since p->state == TASK_WAKING, set_task_cpu() has been called
1619 * from try_to_wake_up(). Hence, p->pi_lock is locked, but
1620 * rq->lock is not... So, lock it
1622 raw_spin_lock(&rq
->lock
);
1623 if (p
->dl
.dl_non_contending
) {
1624 sub_running_bw(&p
->dl
, &rq
->dl
);
1625 p
->dl
.dl_non_contending
= 0;
1627 * If the timer handler is currently running and the
1628 * timer cannot be cancelled, inactive_task_timer()
1629 * will see that dl_not_contending is not set, and
1630 * will not touch the rq's active utilization,
1631 * so we are still safe.
1633 if (hrtimer_try_to_cancel(&p
->dl
.inactive_timer
) == 1)
1636 sub_rq_bw(&p
->dl
, &rq
->dl
);
1637 raw_spin_unlock(&rq
->lock
);
1640 static void check_preempt_equal_dl(struct rq
*rq
, struct task_struct
*p
)
1643 * Current can't be migrated, useless to reschedule,
1644 * let's hope p can move out.
1646 if (rq
->curr
->nr_cpus_allowed
== 1 ||
1647 !cpudl_find(&rq
->rd
->cpudl
, rq
->curr
, NULL
))
1651 * p is migratable, so let's not schedule it and
1652 * see if it is pushed or pulled somewhere else.
1654 if (p
->nr_cpus_allowed
!= 1 &&
1655 cpudl_find(&rq
->rd
->cpudl
, p
, NULL
))
1661 #endif /* CONFIG_SMP */
1664 * Only called when both the current and waking task are -deadline
1667 static void check_preempt_curr_dl(struct rq
*rq
, struct task_struct
*p
,
1670 if (dl_entity_preempt(&p
->dl
, &rq
->curr
->dl
)) {
1677 * In the unlikely case current and p have the same deadline
1678 * let us try to decide what's the best thing to do...
1680 if ((p
->dl
.deadline
== rq
->curr
->dl
.deadline
) &&
1681 !test_tsk_need_resched(rq
->curr
))
1682 check_preempt_equal_dl(rq
, p
);
1683 #endif /* CONFIG_SMP */
1686 #ifdef CONFIG_SCHED_HRTICK
1687 static void start_hrtick_dl(struct rq
*rq
, struct task_struct
*p
)
1689 hrtick_start(rq
, p
->dl
.runtime
);
1691 #else /* !CONFIG_SCHED_HRTICK */
1692 static void start_hrtick_dl(struct rq
*rq
, struct task_struct
*p
)
1697 static inline void set_next_task(struct rq
*rq
, struct task_struct
*p
)
1699 p
->se
.exec_start
= rq_clock_task(rq
);
1701 /* You can't push away the running task */
1702 dequeue_pushable_dl_task(rq
, p
);
1705 static struct sched_dl_entity
*pick_next_dl_entity(struct rq
*rq
,
1706 struct dl_rq
*dl_rq
)
1708 struct rb_node
*left
= rb_first_cached(&dl_rq
->root
);
1713 return rb_entry(left
, struct sched_dl_entity
, rb_node
);
1716 static struct task_struct
*
1717 pick_next_task_dl(struct rq
*rq
, struct task_struct
*prev
, struct rq_flags
*rf
)
1719 struct sched_dl_entity
*dl_se
;
1720 struct task_struct
*p
;
1721 struct dl_rq
*dl_rq
;
1725 if (need_pull_dl_task(rq
, prev
)) {
1727 * This is OK, because current is on_cpu, which avoids it being
1728 * picked for load-balance and preemption/IRQs are still
1729 * disabled avoiding further scheduler activity on it and we're
1730 * being very careful to re-start the picking loop.
1732 rq_unpin_lock(rq
, rf
);
1734 rq_repin_lock(rq
, rf
);
1736 * pull_dl_task() can drop (and re-acquire) rq->lock; this
1737 * means a stop task can slip in, in which case we need to
1738 * re-start task selection.
1740 if (rq
->stop
&& task_on_rq_queued(rq
->stop
))
1745 * When prev is DL, we may throttle it in put_prev_task().
1746 * So, we update time before we check for dl_nr_running.
1748 if (prev
->sched_class
== &dl_sched_class
)
1751 if (unlikely(!dl_rq
->dl_nr_running
))
1754 put_prev_task(rq
, prev
);
1756 dl_se
= pick_next_dl_entity(rq
, dl_rq
);
1759 p
= dl_task_of(dl_se
);
1761 set_next_task(rq
, p
);
1763 if (hrtick_enabled(rq
))
1764 start_hrtick_dl(rq
, p
);
1766 deadline_queue_push_tasks(rq
);
1768 if (rq
->curr
->sched_class
!= &dl_sched_class
)
1769 update_dl_rq_load_avg(rq_clock_pelt(rq
), rq
, 0);
1774 static void put_prev_task_dl(struct rq
*rq
, struct task_struct
*p
)
1778 update_dl_rq_load_avg(rq_clock_pelt(rq
), rq
, 1);
1779 if (on_dl_rq(&p
->dl
) && p
->nr_cpus_allowed
> 1)
1780 enqueue_pushable_dl_task(rq
, p
);
1784 * scheduler tick hitting a task of our scheduling class.
1786 * NOTE: This function can be called remotely by the tick offload that
1787 * goes along full dynticks. Therefore no local assumption can be made
1788 * and everything must be accessed through the @rq and @curr passed in
1791 static void task_tick_dl(struct rq
*rq
, struct task_struct
*p
, int queued
)
1795 update_dl_rq_load_avg(rq_clock_pelt(rq
), rq
, 1);
1797 * Even when we have runtime, update_curr_dl() might have resulted in us
1798 * not being the leftmost task anymore. In that case NEED_RESCHED will
1799 * be set and schedule() will start a new hrtick for the next task.
1801 if (hrtick_enabled(rq
) && queued
&& p
->dl
.runtime
> 0 &&
1802 is_leftmost(p
, &rq
->dl
))
1803 start_hrtick_dl(rq
, p
);
1806 static void task_fork_dl(struct task_struct
*p
)
1809 * SCHED_DEADLINE tasks cannot fork and this is achieved through
1814 static void set_curr_task_dl(struct rq
*rq
)
1816 set_next_task(rq
, rq
->curr
);
1821 /* Only try algorithms three times */
1822 #define DL_MAX_TRIES 3
1824 static int pick_dl_task(struct rq
*rq
, struct task_struct
*p
, int cpu
)
1826 if (!task_running(rq
, p
) &&
1827 cpumask_test_cpu(cpu
, p
->cpus_ptr
))
1833 * Return the earliest pushable rq's task, which is suitable to be executed
1834 * on the CPU, NULL otherwise:
1836 static struct task_struct
*pick_earliest_pushable_dl_task(struct rq
*rq
, int cpu
)
1838 struct rb_node
*next_node
= rq
->dl
.pushable_dl_tasks_root
.rb_leftmost
;
1839 struct task_struct
*p
= NULL
;
1841 if (!has_pushable_dl_tasks(rq
))
1846 p
= rb_entry(next_node
, struct task_struct
, pushable_dl_tasks
);
1848 if (pick_dl_task(rq
, p
, cpu
))
1851 next_node
= rb_next(next_node
);
1858 static DEFINE_PER_CPU(cpumask_var_t
, local_cpu_mask_dl
);
1860 static int find_later_rq(struct task_struct
*task
)
1862 struct sched_domain
*sd
;
1863 struct cpumask
*later_mask
= this_cpu_cpumask_var_ptr(local_cpu_mask_dl
);
1864 int this_cpu
= smp_processor_id();
1865 int cpu
= task_cpu(task
);
1867 /* Make sure the mask is initialized first */
1868 if (unlikely(!later_mask
))
1871 if (task
->nr_cpus_allowed
== 1)
1875 * We have to consider system topology and task affinity
1876 * first, then we can look for a suitable CPU.
1878 if (!cpudl_find(&task_rq(task
)->rd
->cpudl
, task
, later_mask
))
1882 * If we are here, some targets have been found, including
1883 * the most suitable which is, among the runqueues where the
1884 * current tasks have later deadlines than the task's one, the
1885 * rq with the latest possible one.
1887 * Now we check how well this matches with task's
1888 * affinity and system topology.
1890 * The last CPU where the task run is our first
1891 * guess, since it is most likely cache-hot there.
1893 if (cpumask_test_cpu(cpu
, later_mask
))
1896 * Check if this_cpu is to be skipped (i.e., it is
1897 * not in the mask) or not.
1899 if (!cpumask_test_cpu(this_cpu
, later_mask
))
1903 for_each_domain(cpu
, sd
) {
1904 if (sd
->flags
& SD_WAKE_AFFINE
) {
1908 * If possible, preempting this_cpu is
1909 * cheaper than migrating.
1911 if (this_cpu
!= -1 &&
1912 cpumask_test_cpu(this_cpu
, sched_domain_span(sd
))) {
1917 best_cpu
= cpumask_first_and(later_mask
,
1918 sched_domain_span(sd
));
1920 * Last chance: if a CPU being in both later_mask
1921 * and current sd span is valid, that becomes our
1922 * choice. Of course, the latest possible CPU is
1923 * already under consideration through later_mask.
1925 if (best_cpu
< nr_cpu_ids
) {
1934 * At this point, all our guesses failed, we just return
1935 * 'something', and let the caller sort the things out.
1940 cpu
= cpumask_any(later_mask
);
1941 if (cpu
< nr_cpu_ids
)
1947 /* Locks the rq it finds */
1948 static struct rq
*find_lock_later_rq(struct task_struct
*task
, struct rq
*rq
)
1950 struct rq
*later_rq
= NULL
;
1954 for (tries
= 0; tries
< DL_MAX_TRIES
; tries
++) {
1955 cpu
= find_later_rq(task
);
1957 if ((cpu
== -1) || (cpu
== rq
->cpu
))
1960 later_rq
= cpu_rq(cpu
);
1962 if (later_rq
->dl
.dl_nr_running
&&
1963 !dl_time_before(task
->dl
.deadline
,
1964 later_rq
->dl
.earliest_dl
.curr
)) {
1966 * Target rq has tasks of equal or earlier deadline,
1967 * retrying does not release any lock and is unlikely
1968 * to yield a different result.
1974 /* Retry if something changed. */
1975 if (double_lock_balance(rq
, later_rq
)) {
1976 if (unlikely(task_rq(task
) != rq
||
1977 !cpumask_test_cpu(later_rq
->cpu
, task
->cpus_ptr
) ||
1978 task_running(rq
, task
) ||
1980 !task_on_rq_queued(task
))) {
1981 double_unlock_balance(rq
, later_rq
);
1988 * If the rq we found has no -deadline task, or
1989 * its earliest one has a later deadline than our
1990 * task, the rq is a good one.
1992 if (!later_rq
->dl
.dl_nr_running
||
1993 dl_time_before(task
->dl
.deadline
,
1994 later_rq
->dl
.earliest_dl
.curr
))
1997 /* Otherwise we try again. */
1998 double_unlock_balance(rq
, later_rq
);
2005 static struct task_struct
*pick_next_pushable_dl_task(struct rq
*rq
)
2007 struct task_struct
*p
;
2009 if (!has_pushable_dl_tasks(rq
))
2012 p
= rb_entry(rq
->dl
.pushable_dl_tasks_root
.rb_leftmost
,
2013 struct task_struct
, pushable_dl_tasks
);
2015 BUG_ON(rq
->cpu
!= task_cpu(p
));
2016 BUG_ON(task_current(rq
, p
));
2017 BUG_ON(p
->nr_cpus_allowed
<= 1);
2019 BUG_ON(!task_on_rq_queued(p
));
2020 BUG_ON(!dl_task(p
));
2026 * See if the non running -deadline tasks on this rq
2027 * can be sent to some other CPU where they can preempt
2028 * and start executing.
2030 static int push_dl_task(struct rq
*rq
)
2032 struct task_struct
*next_task
;
2033 struct rq
*later_rq
;
2036 if (!rq
->dl
.overloaded
)
2039 next_task
= pick_next_pushable_dl_task(rq
);
2044 if (WARN_ON(next_task
== rq
->curr
))
2048 * If next_task preempts rq->curr, and rq->curr
2049 * can move away, it makes sense to just reschedule
2050 * without going further in pushing next_task.
2052 if (dl_task(rq
->curr
) &&
2053 dl_time_before(next_task
->dl
.deadline
, rq
->curr
->dl
.deadline
) &&
2054 rq
->curr
->nr_cpus_allowed
> 1) {
2059 /* We might release rq lock */
2060 get_task_struct(next_task
);
2062 /* Will lock the rq it'll find */
2063 later_rq
= find_lock_later_rq(next_task
, rq
);
2065 struct task_struct
*task
;
2068 * We must check all this again, since
2069 * find_lock_later_rq releases rq->lock and it is
2070 * then possible that next_task has migrated.
2072 task
= pick_next_pushable_dl_task(rq
);
2073 if (task
== next_task
) {
2075 * The task is still there. We don't try
2076 * again, some other CPU will pull it when ready.
2085 put_task_struct(next_task
);
2090 deactivate_task(rq
, next_task
, 0);
2091 set_task_cpu(next_task
, later_rq
->cpu
);
2094 * Update the later_rq clock here, because the clock is used
2095 * by the cpufreq_update_util() inside __add_running_bw().
2097 update_rq_clock(later_rq
);
2098 activate_task(later_rq
, next_task
, ENQUEUE_NOCLOCK
);
2101 resched_curr(later_rq
);
2103 double_unlock_balance(rq
, later_rq
);
2106 put_task_struct(next_task
);
2111 static void push_dl_tasks(struct rq
*rq
)
2113 /* push_dl_task() will return true if it moved a -deadline task */
2114 while (push_dl_task(rq
))
2118 static void pull_dl_task(struct rq
*this_rq
)
2120 int this_cpu
= this_rq
->cpu
, cpu
;
2121 struct task_struct
*p
;
2122 bool resched
= false;
2124 u64 dmin
= LONG_MAX
;
2126 if (likely(!dl_overloaded(this_rq
)))
2130 * Match the barrier from dl_set_overloaded; this guarantees that if we
2131 * see overloaded we must also see the dlo_mask bit.
2135 for_each_cpu(cpu
, this_rq
->rd
->dlo_mask
) {
2136 if (this_cpu
== cpu
)
2139 src_rq
= cpu_rq(cpu
);
2142 * It looks racy, abd it is! However, as in sched_rt.c,
2143 * we are fine with this.
2145 if (this_rq
->dl
.dl_nr_running
&&
2146 dl_time_before(this_rq
->dl
.earliest_dl
.curr
,
2147 src_rq
->dl
.earliest_dl
.next
))
2150 /* Might drop this_rq->lock */
2151 double_lock_balance(this_rq
, src_rq
);
2154 * If there are no more pullable tasks on the
2155 * rq, we're done with it.
2157 if (src_rq
->dl
.dl_nr_running
<= 1)
2160 p
= pick_earliest_pushable_dl_task(src_rq
, this_cpu
);
2163 * We found a task to be pulled if:
2164 * - it preempts our current (if there's one),
2165 * - it will preempt the last one we pulled (if any).
2167 if (p
&& dl_time_before(p
->dl
.deadline
, dmin
) &&
2168 (!this_rq
->dl
.dl_nr_running
||
2169 dl_time_before(p
->dl
.deadline
,
2170 this_rq
->dl
.earliest_dl
.curr
))) {
2171 WARN_ON(p
== src_rq
->curr
);
2172 WARN_ON(!task_on_rq_queued(p
));
2175 * Then we pull iff p has actually an earlier
2176 * deadline than the current task of its runqueue.
2178 if (dl_time_before(p
->dl
.deadline
,
2179 src_rq
->curr
->dl
.deadline
))
2184 deactivate_task(src_rq
, p
, 0);
2185 set_task_cpu(p
, this_cpu
);
2186 activate_task(this_rq
, p
, 0);
2187 dmin
= p
->dl
.deadline
;
2189 /* Is there any other task even earlier? */
2192 double_unlock_balance(this_rq
, src_rq
);
2196 resched_curr(this_rq
);
2200 * Since the task is not running and a reschedule is not going to happen
2201 * anytime soon on its runqueue, we try pushing it away now.
2203 static void task_woken_dl(struct rq
*rq
, struct task_struct
*p
)
2205 if (!task_running(rq
, p
) &&
2206 !test_tsk_need_resched(rq
->curr
) &&
2207 p
->nr_cpus_allowed
> 1 &&
2208 dl_task(rq
->curr
) &&
2209 (rq
->curr
->nr_cpus_allowed
< 2 ||
2210 !dl_entity_preempt(&p
->dl
, &rq
->curr
->dl
))) {
2215 static void set_cpus_allowed_dl(struct task_struct
*p
,
2216 const struct cpumask
*new_mask
)
2218 struct root_domain
*src_rd
;
2221 BUG_ON(!dl_task(p
));
2226 * Migrating a SCHED_DEADLINE task between exclusive
2227 * cpusets (different root_domains) entails a bandwidth
2228 * update. We already made space for us in the destination
2229 * domain (see cpuset_can_attach()).
2231 if (!cpumask_intersects(src_rd
->span
, new_mask
)) {
2232 struct dl_bw
*src_dl_b
;
2234 src_dl_b
= dl_bw_of(cpu_of(rq
));
2236 * We now free resources of the root_domain we are migrating
2237 * off. In the worst case, sched_setattr() may temporary fail
2238 * until we complete the update.
2240 raw_spin_lock(&src_dl_b
->lock
);
2241 __dl_sub(src_dl_b
, p
->dl
.dl_bw
, dl_bw_cpus(task_cpu(p
)));
2242 raw_spin_unlock(&src_dl_b
->lock
);
2245 set_cpus_allowed_common(p
, new_mask
);
2248 /* Assumes rq->lock is held */
2249 static void rq_online_dl(struct rq
*rq
)
2251 if (rq
->dl
.overloaded
)
2252 dl_set_overload(rq
);
2254 cpudl_set_freecpu(&rq
->rd
->cpudl
, rq
->cpu
);
2255 if (rq
->dl
.dl_nr_running
> 0)
2256 cpudl_set(&rq
->rd
->cpudl
, rq
->cpu
, rq
->dl
.earliest_dl
.curr
);
2259 /* Assumes rq->lock is held */
2260 static void rq_offline_dl(struct rq
*rq
)
2262 if (rq
->dl
.overloaded
)
2263 dl_clear_overload(rq
);
2265 cpudl_clear(&rq
->rd
->cpudl
, rq
->cpu
);
2266 cpudl_clear_freecpu(&rq
->rd
->cpudl
, rq
->cpu
);
2269 void __init
init_sched_dl_class(void)
2273 for_each_possible_cpu(i
)
2274 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl
, i
),
2275 GFP_KERNEL
, cpu_to_node(i
));
2278 #endif /* CONFIG_SMP */
2280 static void switched_from_dl(struct rq
*rq
, struct task_struct
*p
)
2283 * task_non_contending() can start the "inactive timer" (if the 0-lag
2284 * time is in the future). If the task switches back to dl before
2285 * the "inactive timer" fires, it can continue to consume its current
2286 * runtime using its current deadline. If it stays outside of
2287 * SCHED_DEADLINE until the 0-lag time passes, inactive_task_timer()
2288 * will reset the task parameters.
2290 if (task_on_rq_queued(p
) && p
->dl
.dl_runtime
)
2291 task_non_contending(p
);
2293 if (!task_on_rq_queued(p
)) {
2295 * Inactive timer is armed. However, p is leaving DEADLINE and
2296 * might migrate away from this rq while continuing to run on
2297 * some other class. We need to remove its contribution from
2298 * this rq running_bw now, or sub_rq_bw (below) will complain.
2300 if (p
->dl
.dl_non_contending
)
2301 sub_running_bw(&p
->dl
, &rq
->dl
);
2302 sub_rq_bw(&p
->dl
, &rq
->dl
);
2306 * We cannot use inactive_task_timer() to invoke sub_running_bw()
2307 * at the 0-lag time, because the task could have been migrated
2308 * while SCHED_OTHER in the meanwhile.
2310 if (p
->dl
.dl_non_contending
)
2311 p
->dl
.dl_non_contending
= 0;
2314 * Since this might be the only -deadline task on the rq,
2315 * this is the right place to try to pull some other one
2316 * from an overloaded CPU, if any.
2318 if (!task_on_rq_queued(p
) || rq
->dl
.dl_nr_running
)
2321 deadline_queue_pull_task(rq
);
2325 * When switching to -deadline, we may overload the rq, then
2326 * we try to push someone off, if possible.
2328 static void switched_to_dl(struct rq
*rq
, struct task_struct
*p
)
2330 if (hrtimer_try_to_cancel(&p
->dl
.inactive_timer
) == 1)
2333 /* If p is not queued we will update its parameters at next wakeup. */
2334 if (!task_on_rq_queued(p
)) {
2335 add_rq_bw(&p
->dl
, &rq
->dl
);
2340 if (rq
->curr
!= p
) {
2342 if (p
->nr_cpus_allowed
> 1 && rq
->dl
.overloaded
)
2343 deadline_queue_push_tasks(rq
);
2345 if (dl_task(rq
->curr
))
2346 check_preempt_curr_dl(rq
, p
, 0);
2353 * If the scheduling parameters of a -deadline task changed,
2354 * a push or pull operation might be needed.
2356 static void prio_changed_dl(struct rq
*rq
, struct task_struct
*p
,
2359 if (task_on_rq_queued(p
) || rq
->curr
== p
) {
2362 * This might be too much, but unfortunately
2363 * we don't have the old deadline value, and
2364 * we can't argue if the task is increasing
2365 * or lowering its prio, so...
2367 if (!rq
->dl
.overloaded
)
2368 deadline_queue_pull_task(rq
);
2371 * If we now have a earlier deadline task than p,
2372 * then reschedule, provided p is still on this
2375 if (dl_time_before(rq
->dl
.earliest_dl
.curr
, p
->dl
.deadline
))
2379 * Again, we don't know if p has a earlier
2380 * or later deadline, so let's blindly set a
2381 * (maybe not needed) rescheduling point.
2384 #endif /* CONFIG_SMP */
2388 const struct sched_class dl_sched_class
= {
2389 .next
= &rt_sched_class
,
2390 .enqueue_task
= enqueue_task_dl
,
2391 .dequeue_task
= dequeue_task_dl
,
2392 .yield_task
= yield_task_dl
,
2394 .check_preempt_curr
= check_preempt_curr_dl
,
2396 .pick_next_task
= pick_next_task_dl
,
2397 .put_prev_task
= put_prev_task_dl
,
2400 .select_task_rq
= select_task_rq_dl
,
2401 .migrate_task_rq
= migrate_task_rq_dl
,
2402 .set_cpus_allowed
= set_cpus_allowed_dl
,
2403 .rq_online
= rq_online_dl
,
2404 .rq_offline
= rq_offline_dl
,
2405 .task_woken
= task_woken_dl
,
2408 .set_curr_task
= set_curr_task_dl
,
2409 .task_tick
= task_tick_dl
,
2410 .task_fork
= task_fork_dl
,
2412 .prio_changed
= prio_changed_dl
,
2413 .switched_from
= switched_from_dl
,
2414 .switched_to
= switched_to_dl
,
2416 .update_curr
= update_curr_dl
,
2419 int sched_dl_global_validate(void)
2421 u64 runtime
= global_rt_runtime();
2422 u64 period
= global_rt_period();
2423 u64 new_bw
= to_ratio(period
, runtime
);
2426 unsigned long flags
;
2429 * Here we want to check the bandwidth not being set to some
2430 * value smaller than the currently allocated bandwidth in
2431 * any of the root_domains.
2433 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
2434 * cycling on root_domains... Discussion on different/better
2435 * solutions is welcome!
2437 for_each_possible_cpu(cpu
) {
2438 rcu_read_lock_sched();
2439 dl_b
= dl_bw_of(cpu
);
2441 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
2442 if (new_bw
< dl_b
->total_bw
)
2444 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
2446 rcu_read_unlock_sched();
2455 void init_dl_rq_bw_ratio(struct dl_rq
*dl_rq
)
2457 if (global_rt_runtime() == RUNTIME_INF
) {
2458 dl_rq
->bw_ratio
= 1 << RATIO_SHIFT
;
2459 dl_rq
->extra_bw
= 1 << BW_SHIFT
;
2461 dl_rq
->bw_ratio
= to_ratio(global_rt_runtime(),
2462 global_rt_period()) >> (BW_SHIFT
- RATIO_SHIFT
);
2463 dl_rq
->extra_bw
= to_ratio(global_rt_period(),
2464 global_rt_runtime());
2468 void sched_dl_do_global(void)
2473 unsigned long flags
;
2475 def_dl_bandwidth
.dl_period
= global_rt_period();
2476 def_dl_bandwidth
.dl_runtime
= global_rt_runtime();
2478 if (global_rt_runtime() != RUNTIME_INF
)
2479 new_bw
= to_ratio(global_rt_period(), global_rt_runtime());
2482 * FIXME: As above...
2484 for_each_possible_cpu(cpu
) {
2485 rcu_read_lock_sched();
2486 dl_b
= dl_bw_of(cpu
);
2488 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
2490 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
2492 rcu_read_unlock_sched();
2493 init_dl_rq_bw_ratio(&cpu_rq(cpu
)->dl
);
2498 * We must be sure that accepting a new task (or allowing changing the
2499 * parameters of an existing one) is consistent with the bandwidth
2500 * constraints. If yes, this function also accordingly updates the currently
2501 * allocated bandwidth to reflect the new situation.
2503 * This function is called while holding p's rq->lock.
2505 int sched_dl_overflow(struct task_struct
*p
, int policy
,
2506 const struct sched_attr
*attr
)
2508 struct dl_bw
*dl_b
= dl_bw_of(task_cpu(p
));
2509 u64 period
= attr
->sched_period
?: attr
->sched_deadline
;
2510 u64 runtime
= attr
->sched_runtime
;
2511 u64 new_bw
= dl_policy(policy
) ? to_ratio(period
, runtime
) : 0;
2514 if (attr
->sched_flags
& SCHED_FLAG_SUGOV
)
2517 /* !deadline task may carry old deadline bandwidth */
2518 if (new_bw
== p
->dl
.dl_bw
&& task_has_dl_policy(p
))
2522 * Either if a task, enters, leave, or stays -deadline but changes
2523 * its parameters, we may need to update accordingly the total
2524 * allocated bandwidth of the container.
2526 raw_spin_lock(&dl_b
->lock
);
2527 cpus
= dl_bw_cpus(task_cpu(p
));
2528 if (dl_policy(policy
) && !task_has_dl_policy(p
) &&
2529 !__dl_overflow(dl_b
, cpus
, 0, new_bw
)) {
2530 if (hrtimer_active(&p
->dl
.inactive_timer
))
2531 __dl_sub(dl_b
, p
->dl
.dl_bw
, cpus
);
2532 __dl_add(dl_b
, new_bw
, cpus
);
2534 } else if (dl_policy(policy
) && task_has_dl_policy(p
) &&
2535 !__dl_overflow(dl_b
, cpus
, p
->dl
.dl_bw
, new_bw
)) {
2537 * XXX this is slightly incorrect: when the task
2538 * utilization decreases, we should delay the total
2539 * utilization change until the task's 0-lag point.
2540 * But this would require to set the task's "inactive
2541 * timer" when the task is not inactive.
2543 __dl_sub(dl_b
, p
->dl
.dl_bw
, cpus
);
2544 __dl_add(dl_b
, new_bw
, cpus
);
2545 dl_change_utilization(p
, new_bw
);
2547 } else if (!dl_policy(policy
) && task_has_dl_policy(p
)) {
2549 * Do not decrease the total deadline utilization here,
2550 * switched_from_dl() will take care to do it at the correct
2555 raw_spin_unlock(&dl_b
->lock
);
2561 * This function initializes the sched_dl_entity of a newly becoming
2562 * SCHED_DEADLINE task.
2564 * Only the static values are considered here, the actual runtime and the
2565 * absolute deadline will be properly calculated when the task is enqueued
2566 * for the first time with its new policy.
2568 void __setparam_dl(struct task_struct
*p
, const struct sched_attr
*attr
)
2570 struct sched_dl_entity
*dl_se
= &p
->dl
;
2572 dl_se
->dl_runtime
= attr
->sched_runtime
;
2573 dl_se
->dl_deadline
= attr
->sched_deadline
;
2574 dl_se
->dl_period
= attr
->sched_period
?: dl_se
->dl_deadline
;
2575 dl_se
->flags
= attr
->sched_flags
;
2576 dl_se
->dl_bw
= to_ratio(dl_se
->dl_period
, dl_se
->dl_runtime
);
2577 dl_se
->dl_density
= to_ratio(dl_se
->dl_deadline
, dl_se
->dl_runtime
);
2580 void __getparam_dl(struct task_struct
*p
, struct sched_attr
*attr
)
2582 struct sched_dl_entity
*dl_se
= &p
->dl
;
2584 attr
->sched_priority
= p
->rt_priority
;
2585 attr
->sched_runtime
= dl_se
->dl_runtime
;
2586 attr
->sched_deadline
= dl_se
->dl_deadline
;
2587 attr
->sched_period
= dl_se
->dl_period
;
2588 attr
->sched_flags
= dl_se
->flags
;
2592 * This function validates the new parameters of a -deadline task.
2593 * We ask for the deadline not being zero, and greater or equal
2594 * than the runtime, as well as the period of being zero or
2595 * greater than deadline. Furthermore, we have to be sure that
2596 * user parameters are above the internal resolution of 1us (we
2597 * check sched_runtime only since it is always the smaller one) and
2598 * below 2^63 ns (we have to check both sched_deadline and
2599 * sched_period, as the latter can be zero).
2601 bool __checkparam_dl(const struct sched_attr
*attr
)
2603 /* special dl tasks don't actually use any parameter */
2604 if (attr
->sched_flags
& SCHED_FLAG_SUGOV
)
2608 if (attr
->sched_deadline
== 0)
2612 * Since we truncate DL_SCALE bits, make sure we're at least
2615 if (attr
->sched_runtime
< (1ULL << DL_SCALE
))
2619 * Since we use the MSB for wrap-around and sign issues, make
2620 * sure it's not set (mind that period can be equal to zero).
2622 if (attr
->sched_deadline
& (1ULL << 63) ||
2623 attr
->sched_period
& (1ULL << 63))
2626 /* runtime <= deadline <= period (if period != 0) */
2627 if ((attr
->sched_period
!= 0 &&
2628 attr
->sched_period
< attr
->sched_deadline
) ||
2629 attr
->sched_deadline
< attr
->sched_runtime
)
2636 * This function clears the sched_dl_entity static params.
2638 void __dl_clear_params(struct task_struct
*p
)
2640 struct sched_dl_entity
*dl_se
= &p
->dl
;
2642 dl_se
->dl_runtime
= 0;
2643 dl_se
->dl_deadline
= 0;
2644 dl_se
->dl_period
= 0;
2647 dl_se
->dl_density
= 0;
2649 dl_se
->dl_throttled
= 0;
2650 dl_se
->dl_yielded
= 0;
2651 dl_se
->dl_non_contending
= 0;
2652 dl_se
->dl_overrun
= 0;
2655 bool dl_param_changed(struct task_struct
*p
, const struct sched_attr
*attr
)
2657 struct sched_dl_entity
*dl_se
= &p
->dl
;
2659 if (dl_se
->dl_runtime
!= attr
->sched_runtime
||
2660 dl_se
->dl_deadline
!= attr
->sched_deadline
||
2661 dl_se
->dl_period
!= attr
->sched_period
||
2662 dl_se
->flags
!= attr
->sched_flags
)
2669 int dl_task_can_attach(struct task_struct
*p
, const struct cpumask
*cs_cpus_allowed
)
2671 unsigned int dest_cpu
;
2675 unsigned long flags
;
2677 dest_cpu
= cpumask_any_and(cpu_active_mask
, cs_cpus_allowed
);
2679 rcu_read_lock_sched();
2680 dl_b
= dl_bw_of(dest_cpu
);
2681 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
2682 cpus
= dl_bw_cpus(dest_cpu
);
2683 overflow
= __dl_overflow(dl_b
, cpus
, 0, p
->dl
.dl_bw
);
2688 * We reserve space for this task in the destination
2689 * root_domain, as we can't fail after this point.
2690 * We will free resources in the source root_domain
2691 * later on (see set_cpus_allowed_dl()).
2693 __dl_add(dl_b
, p
->dl
.dl_bw
, cpus
);
2696 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
2697 rcu_read_unlock_sched();
2702 int dl_cpuset_cpumask_can_shrink(const struct cpumask
*cur
,
2703 const struct cpumask
*trial
)
2705 int ret
= 1, trial_cpus
;
2706 struct dl_bw
*cur_dl_b
;
2707 unsigned long flags
;
2709 rcu_read_lock_sched();
2710 cur_dl_b
= dl_bw_of(cpumask_any(cur
));
2711 trial_cpus
= cpumask_weight(trial
);
2713 raw_spin_lock_irqsave(&cur_dl_b
->lock
, flags
);
2714 if (cur_dl_b
->bw
!= -1 &&
2715 cur_dl_b
->bw
* trial_cpus
< cur_dl_b
->total_bw
)
2717 raw_spin_unlock_irqrestore(&cur_dl_b
->lock
, flags
);
2718 rcu_read_unlock_sched();
2723 bool dl_cpu_busy(unsigned int cpu
)
2725 unsigned long flags
;
2730 rcu_read_lock_sched();
2731 dl_b
= dl_bw_of(cpu
);
2732 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
2733 cpus
= dl_bw_cpus(cpu
);
2734 overflow
= __dl_overflow(dl_b
, cpus
, 0, 0);
2735 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
2736 rcu_read_unlock_sched();
2742 #ifdef CONFIG_SCHED_DEBUG
2743 void print_dl_stats(struct seq_file
*m
, int cpu
)
2745 print_dl_rq(m
, cpu
, &cpu_rq(cpu
)->dl
);
2747 #endif /* CONFIG_SCHED_DEBUG */