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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
aab03e05 DF |
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>, | |
1baca4ce | 14 | * Juri Lelli <juri.lelli@gmail.com>, |
aab03e05 DF |
15 | * Michael Trimarchi <michael@amarulasolutions.com>, |
16 | * Fabio Checconi <fchecconi@gmail.com> | |
17 | */ | |
18 | #include "sched.h" | |
19 | ||
6bfd6d72 | 20 | #include <linux/slab.h> |
06a76fe0 | 21 | #include <uapi/linux/sched/types.h> |
6bfd6d72 | 22 | |
332ac17e DF |
23 | struct dl_bandwidth def_dl_bandwidth; |
24 | ||
aab03e05 DF |
25 | static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se) |
26 | { | |
27 | return container_of(dl_se, struct task_struct, dl); | |
28 | } | |
29 | ||
30 | static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq) | |
31 | { | |
32 | return container_of(dl_rq, struct rq, dl); | |
33 | } | |
34 | ||
35 | static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se) | |
36 | { | |
37 | struct task_struct *p = dl_task_of(dl_se); | |
38 | struct rq *rq = task_rq(p); | |
39 | ||
40 | return &rq->dl; | |
41 | } | |
42 | ||
43 | static inline int on_dl_rq(struct sched_dl_entity *dl_se) | |
44 | { | |
45 | return !RB_EMPTY_NODE(&dl_se->rb_node); | |
46 | } | |
47 | ||
06a76fe0 NP |
48 | #ifdef CONFIG_SMP |
49 | static inline struct dl_bw *dl_bw_of(int i) | |
50 | { | |
51 | RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), | |
52 | "sched RCU must be held"); | |
53 | return &cpu_rq(i)->rd->dl_bw; | |
54 | } | |
55 | ||
56 | static inline int dl_bw_cpus(int i) | |
57 | { | |
58 | struct root_domain *rd = cpu_rq(i)->rd; | |
59 | int cpus = 0; | |
60 | ||
61 | RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), | |
62 | "sched RCU must be held"); | |
63 | for_each_cpu_and(i, rd->span, cpu_active_mask) | |
64 | cpus++; | |
65 | ||
66 | return cpus; | |
67 | } | |
68 | #else | |
69 | static inline struct dl_bw *dl_bw_of(int i) | |
70 | { | |
71 | return &cpu_rq(i)->dl.dl_bw; | |
72 | } | |
73 | ||
74 | static inline int dl_bw_cpus(int i) | |
75 | { | |
76 | return 1; | |
77 | } | |
78 | #endif | |
79 | ||
e36d8677 LA |
80 | static inline |
81 | void add_running_bw(u64 dl_bw, struct dl_rq *dl_rq) | |
82 | { | |
83 | u64 old = dl_rq->running_bw; | |
84 | ||
85 | lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); | |
86 | dl_rq->running_bw += dl_bw; | |
87 | SCHED_WARN_ON(dl_rq->running_bw < old); /* overflow */ | |
8fd27231 | 88 | SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw); |
e0367b12 JL |
89 | /* kick cpufreq (see the comment in kernel/sched/sched.h). */ |
90 | cpufreq_update_util(rq_of_dl_rq(dl_rq), SCHED_CPUFREQ_DL); | |
e36d8677 LA |
91 | } |
92 | ||
93 | static inline | |
94 | void sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq) | |
95 | { | |
96 | u64 old = dl_rq->running_bw; | |
97 | ||
98 | lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); | |
99 | dl_rq->running_bw -= dl_bw; | |
100 | SCHED_WARN_ON(dl_rq->running_bw > old); /* underflow */ | |
101 | if (dl_rq->running_bw > old) | |
102 | dl_rq->running_bw = 0; | |
e0367b12 JL |
103 | /* kick cpufreq (see the comment in kernel/sched/sched.h). */ |
104 | cpufreq_update_util(rq_of_dl_rq(dl_rq), SCHED_CPUFREQ_DL); | |
e36d8677 LA |
105 | } |
106 | ||
8fd27231 LA |
107 | static inline |
108 | void add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq) | |
109 | { | |
110 | u64 old = dl_rq->this_bw; | |
111 | ||
112 | lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); | |
113 | dl_rq->this_bw += dl_bw; | |
114 | SCHED_WARN_ON(dl_rq->this_bw < old); /* overflow */ | |
115 | } | |
116 | ||
117 | static inline | |
118 | void sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq) | |
119 | { | |
120 | u64 old = dl_rq->this_bw; | |
121 | ||
122 | lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); | |
123 | dl_rq->this_bw -= dl_bw; | |
124 | SCHED_WARN_ON(dl_rq->this_bw > old); /* underflow */ | |
125 | if (dl_rq->this_bw > old) | |
126 | dl_rq->this_bw = 0; | |
127 | SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw); | |
128 | } | |
129 | ||
209a0cbd LA |
130 | void dl_change_utilization(struct task_struct *p, u64 new_bw) |
131 | { | |
8fd27231 | 132 | struct rq *rq; |
209a0cbd | 133 | |
8fd27231 | 134 | if (task_on_rq_queued(p)) |
209a0cbd LA |
135 | return; |
136 | ||
8fd27231 LA |
137 | rq = task_rq(p); |
138 | if (p->dl.dl_non_contending) { | |
139 | sub_running_bw(p->dl.dl_bw, &rq->dl); | |
140 | p->dl.dl_non_contending = 0; | |
141 | /* | |
142 | * If the timer handler is currently running and the | |
143 | * timer cannot be cancelled, inactive_task_timer() | |
144 | * will see that dl_not_contending is not set, and | |
145 | * will not touch the rq's active utilization, | |
146 | * so we are still safe. | |
147 | */ | |
148 | if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1) | |
149 | put_task_struct(p); | |
150 | } | |
151 | sub_rq_bw(p->dl.dl_bw, &rq->dl); | |
152 | add_rq_bw(new_bw, &rq->dl); | |
209a0cbd LA |
153 | } |
154 | ||
155 | /* | |
156 | * The utilization of a task cannot be immediately removed from | |
157 | * the rq active utilization (running_bw) when the task blocks. | |
158 | * Instead, we have to wait for the so called "0-lag time". | |
159 | * | |
160 | * If a task blocks before the "0-lag time", a timer (the inactive | |
161 | * timer) is armed, and running_bw is decreased when the timer | |
162 | * fires. | |
163 | * | |
164 | * If the task wakes up again before the inactive timer fires, | |
165 | * the timer is cancelled, whereas if the task wakes up after the | |
166 | * inactive timer fired (and running_bw has been decreased) the | |
167 | * task's utilization has to be added to running_bw again. | |
168 | * A flag in the deadline scheduling entity (dl_non_contending) | |
169 | * is used to avoid race conditions between the inactive timer handler | |
170 | * and task wakeups. | |
171 | * | |
172 | * The following diagram shows how running_bw is updated. A task is | |
173 | * "ACTIVE" when its utilization contributes to running_bw; an | |
174 | * "ACTIVE contending" task is in the TASK_RUNNING state, while an | |
175 | * "ACTIVE non contending" task is a blocked task for which the "0-lag time" | |
176 | * has not passed yet. An "INACTIVE" task is a task for which the "0-lag" | |
177 | * time already passed, which does not contribute to running_bw anymore. | |
178 | * +------------------+ | |
179 | * wakeup | ACTIVE | | |
180 | * +------------------>+ contending | | |
181 | * | add_running_bw | | | |
182 | * | +----+------+------+ | |
183 | * | | ^ | |
184 | * | dequeue | | | |
185 | * +--------+-------+ | | | |
186 | * | | t >= 0-lag | | wakeup | |
187 | * | INACTIVE |<---------------+ | | |
188 | * | | sub_running_bw | | | |
189 | * +--------+-------+ | | | |
190 | * ^ | | | |
191 | * | t < 0-lag | | | |
192 | * | | | | |
193 | * | V | | |
194 | * | +----+------+------+ | |
195 | * | sub_running_bw | ACTIVE | | |
196 | * +-------------------+ | | |
197 | * inactive timer | non contending | | |
198 | * fired +------------------+ | |
199 | * | |
200 | * The task_non_contending() function is invoked when a task | |
201 | * blocks, and checks if the 0-lag time already passed or | |
202 | * not (in the first case, it directly updates running_bw; | |
203 | * in the second case, it arms the inactive timer). | |
204 | * | |
205 | * The task_contending() function is invoked when a task wakes | |
206 | * up, and checks if the task is still in the "ACTIVE non contending" | |
207 | * state or not (in the second case, it updates running_bw). | |
208 | */ | |
209 | static void task_non_contending(struct task_struct *p) | |
210 | { | |
211 | struct sched_dl_entity *dl_se = &p->dl; | |
212 | struct hrtimer *timer = &dl_se->inactive_timer; | |
213 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
214 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
215 | s64 zerolag_time; | |
216 | ||
217 | /* | |
218 | * If this is a non-deadline task that has been boosted, | |
219 | * do nothing | |
220 | */ | |
221 | if (dl_se->dl_runtime == 0) | |
222 | return; | |
223 | ||
224 | WARN_ON(hrtimer_active(&dl_se->inactive_timer)); | |
225 | WARN_ON(dl_se->dl_non_contending); | |
226 | ||
227 | zerolag_time = dl_se->deadline - | |
228 | div64_long((dl_se->runtime * dl_se->dl_period), | |
229 | dl_se->dl_runtime); | |
230 | ||
231 | /* | |
232 | * Using relative times instead of the absolute "0-lag time" | |
233 | * allows to simplify the code | |
234 | */ | |
235 | zerolag_time -= rq_clock(rq); | |
236 | ||
237 | /* | |
238 | * If the "0-lag time" already passed, decrease the active | |
239 | * utilization now, instead of starting a timer | |
240 | */ | |
241 | if (zerolag_time < 0) { | |
242 | if (dl_task(p)) | |
243 | sub_running_bw(dl_se->dl_bw, dl_rq); | |
387e3130 LA |
244 | if (!dl_task(p) || p->state == TASK_DEAD) { |
245 | struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); | |
246 | ||
8fd27231 LA |
247 | if (p->state == TASK_DEAD) |
248 | sub_rq_bw(p->dl.dl_bw, &rq->dl); | |
387e3130 | 249 | raw_spin_lock(&dl_b->lock); |
8c0944ce | 250 | __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p))); |
209a0cbd | 251 | __dl_clear_params(p); |
387e3130 LA |
252 | raw_spin_unlock(&dl_b->lock); |
253 | } | |
209a0cbd LA |
254 | |
255 | return; | |
256 | } | |
257 | ||
258 | dl_se->dl_non_contending = 1; | |
259 | get_task_struct(p); | |
260 | hrtimer_start(timer, ns_to_ktime(zerolag_time), HRTIMER_MODE_REL); | |
261 | } | |
262 | ||
8fd27231 | 263 | static void task_contending(struct sched_dl_entity *dl_se, int flags) |
209a0cbd LA |
264 | { |
265 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
266 | ||
267 | /* | |
268 | * If this is a non-deadline task that has been boosted, | |
269 | * do nothing | |
270 | */ | |
271 | if (dl_se->dl_runtime == 0) | |
272 | return; | |
273 | ||
8fd27231 LA |
274 | if (flags & ENQUEUE_MIGRATED) |
275 | add_rq_bw(dl_se->dl_bw, dl_rq); | |
276 | ||
209a0cbd LA |
277 | if (dl_se->dl_non_contending) { |
278 | dl_se->dl_non_contending = 0; | |
279 | /* | |
280 | * If the timer handler is currently running and the | |
281 | * timer cannot be cancelled, inactive_task_timer() | |
282 | * will see that dl_not_contending is not set, and | |
283 | * will not touch the rq's active utilization, | |
284 | * so we are still safe. | |
285 | */ | |
286 | if (hrtimer_try_to_cancel(&dl_se->inactive_timer) == 1) | |
287 | put_task_struct(dl_task_of(dl_se)); | |
288 | } else { | |
289 | /* | |
290 | * Since "dl_non_contending" is not set, the | |
291 | * task's utilization has already been removed from | |
292 | * active utilization (either when the task blocked, | |
293 | * when the "inactive timer" fired). | |
294 | * So, add it back. | |
295 | */ | |
296 | add_running_bw(dl_se->dl_bw, dl_rq); | |
297 | } | |
298 | } | |
299 | ||
aab03e05 DF |
300 | static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq) |
301 | { | |
302 | struct sched_dl_entity *dl_se = &p->dl; | |
303 | ||
2161573e | 304 | return dl_rq->root.rb_leftmost == &dl_se->rb_node; |
aab03e05 DF |
305 | } |
306 | ||
332ac17e DF |
307 | void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime) |
308 | { | |
309 | raw_spin_lock_init(&dl_b->dl_runtime_lock); | |
310 | dl_b->dl_period = period; | |
311 | dl_b->dl_runtime = runtime; | |
312 | } | |
313 | ||
332ac17e DF |
314 | void init_dl_bw(struct dl_bw *dl_b) |
315 | { | |
316 | raw_spin_lock_init(&dl_b->lock); | |
317 | raw_spin_lock(&def_dl_bandwidth.dl_runtime_lock); | |
1724813d | 318 | if (global_rt_runtime() == RUNTIME_INF) |
332ac17e DF |
319 | dl_b->bw = -1; |
320 | else | |
1724813d | 321 | dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime()); |
332ac17e DF |
322 | raw_spin_unlock(&def_dl_bandwidth.dl_runtime_lock); |
323 | dl_b->total_bw = 0; | |
324 | } | |
325 | ||
07c54f7a | 326 | void init_dl_rq(struct dl_rq *dl_rq) |
aab03e05 | 327 | { |
2161573e | 328 | dl_rq->root = RB_ROOT_CACHED; |
1baca4ce JL |
329 | |
330 | #ifdef CONFIG_SMP | |
331 | /* zero means no -deadline tasks */ | |
332 | dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0; | |
333 | ||
334 | dl_rq->dl_nr_migratory = 0; | |
335 | dl_rq->overloaded = 0; | |
2161573e | 336 | dl_rq->pushable_dl_tasks_root = RB_ROOT_CACHED; |
332ac17e DF |
337 | #else |
338 | init_dl_bw(&dl_rq->dl_bw); | |
1baca4ce | 339 | #endif |
e36d8677 LA |
340 | |
341 | dl_rq->running_bw = 0; | |
8fd27231 | 342 | dl_rq->this_bw = 0; |
4da3abce | 343 | init_dl_rq_bw_ratio(dl_rq); |
1baca4ce JL |
344 | } |
345 | ||
346 | #ifdef CONFIG_SMP | |
347 | ||
348 | static inline int dl_overloaded(struct rq *rq) | |
349 | { | |
350 | return atomic_read(&rq->rd->dlo_count); | |
351 | } | |
352 | ||
353 | static inline void dl_set_overload(struct rq *rq) | |
354 | { | |
355 | if (!rq->online) | |
356 | return; | |
357 | ||
358 | cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask); | |
359 | /* | |
360 | * Must be visible before the overload count is | |
361 | * set (as in sched_rt.c). | |
362 | * | |
363 | * Matched by the barrier in pull_dl_task(). | |
364 | */ | |
365 | smp_wmb(); | |
366 | atomic_inc(&rq->rd->dlo_count); | |
367 | } | |
368 | ||
369 | static inline void dl_clear_overload(struct rq *rq) | |
370 | { | |
371 | if (!rq->online) | |
372 | return; | |
373 | ||
374 | atomic_dec(&rq->rd->dlo_count); | |
375 | cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask); | |
376 | } | |
377 | ||
378 | static void update_dl_migration(struct dl_rq *dl_rq) | |
379 | { | |
995b9ea4 | 380 | if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_running > 1) { |
1baca4ce JL |
381 | if (!dl_rq->overloaded) { |
382 | dl_set_overload(rq_of_dl_rq(dl_rq)); | |
383 | dl_rq->overloaded = 1; | |
384 | } | |
385 | } else if (dl_rq->overloaded) { | |
386 | dl_clear_overload(rq_of_dl_rq(dl_rq)); | |
387 | dl_rq->overloaded = 0; | |
388 | } | |
389 | } | |
390 | ||
391 | static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
392 | { | |
393 | struct task_struct *p = dl_task_of(dl_se); | |
1baca4ce | 394 | |
4b53a341 | 395 | if (p->nr_cpus_allowed > 1) |
1baca4ce JL |
396 | dl_rq->dl_nr_migratory++; |
397 | ||
398 | update_dl_migration(dl_rq); | |
399 | } | |
400 | ||
401 | static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
402 | { | |
403 | struct task_struct *p = dl_task_of(dl_se); | |
1baca4ce | 404 | |
4b53a341 | 405 | if (p->nr_cpus_allowed > 1) |
1baca4ce JL |
406 | dl_rq->dl_nr_migratory--; |
407 | ||
408 | update_dl_migration(dl_rq); | |
409 | } | |
410 | ||
411 | /* | |
412 | * The list of pushable -deadline task is not a plist, like in | |
413 | * sched_rt.c, it is an rb-tree with tasks ordered by deadline. | |
414 | */ | |
415 | static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p) | |
416 | { | |
417 | struct dl_rq *dl_rq = &rq->dl; | |
2161573e | 418 | struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_root.rb_node; |
1baca4ce JL |
419 | struct rb_node *parent = NULL; |
420 | struct task_struct *entry; | |
2161573e | 421 | bool leftmost = true; |
1baca4ce JL |
422 | |
423 | BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks)); | |
424 | ||
425 | while (*link) { | |
426 | parent = *link; | |
427 | entry = rb_entry(parent, struct task_struct, | |
428 | pushable_dl_tasks); | |
429 | if (dl_entity_preempt(&p->dl, &entry->dl)) | |
430 | link = &parent->rb_left; | |
431 | else { | |
432 | link = &parent->rb_right; | |
2161573e | 433 | leftmost = false; |
1baca4ce JL |
434 | } |
435 | } | |
436 | ||
2161573e | 437 | if (leftmost) |
7d92de3a | 438 | dl_rq->earliest_dl.next = p->dl.deadline; |
1baca4ce JL |
439 | |
440 | rb_link_node(&p->pushable_dl_tasks, parent, link); | |
2161573e DB |
441 | rb_insert_color_cached(&p->pushable_dl_tasks, |
442 | &dl_rq->pushable_dl_tasks_root, leftmost); | |
aab03e05 DF |
443 | } |
444 | ||
1baca4ce JL |
445 | static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p) |
446 | { | |
447 | struct dl_rq *dl_rq = &rq->dl; | |
448 | ||
449 | if (RB_EMPTY_NODE(&p->pushable_dl_tasks)) | |
450 | return; | |
451 | ||
2161573e | 452 | if (dl_rq->pushable_dl_tasks_root.rb_leftmost == &p->pushable_dl_tasks) { |
1baca4ce JL |
453 | struct rb_node *next_node; |
454 | ||
455 | next_node = rb_next(&p->pushable_dl_tasks); | |
7d92de3a WL |
456 | if (next_node) { |
457 | dl_rq->earliest_dl.next = rb_entry(next_node, | |
458 | struct task_struct, pushable_dl_tasks)->dl.deadline; | |
459 | } | |
1baca4ce JL |
460 | } |
461 | ||
2161573e | 462 | rb_erase_cached(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root); |
1baca4ce JL |
463 | RB_CLEAR_NODE(&p->pushable_dl_tasks); |
464 | } | |
465 | ||
466 | static inline int has_pushable_dl_tasks(struct rq *rq) | |
467 | { | |
2161573e | 468 | return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root.rb_root); |
1baca4ce JL |
469 | } |
470 | ||
471 | static int push_dl_task(struct rq *rq); | |
472 | ||
dc877341 PZ |
473 | static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) |
474 | { | |
475 | return dl_task(prev); | |
476 | } | |
477 | ||
9916e214 PZ |
478 | static DEFINE_PER_CPU(struct callback_head, dl_push_head); |
479 | static DEFINE_PER_CPU(struct callback_head, dl_pull_head); | |
e3fca9e7 PZ |
480 | |
481 | static void push_dl_tasks(struct rq *); | |
9916e214 | 482 | static void pull_dl_task(struct rq *); |
e3fca9e7 PZ |
483 | |
484 | static inline void queue_push_tasks(struct rq *rq) | |
dc877341 | 485 | { |
e3fca9e7 PZ |
486 | if (!has_pushable_dl_tasks(rq)) |
487 | return; | |
488 | ||
9916e214 PZ |
489 | queue_balance_callback(rq, &per_cpu(dl_push_head, rq->cpu), push_dl_tasks); |
490 | } | |
491 | ||
492 | static inline void queue_pull_task(struct rq *rq) | |
493 | { | |
494 | queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task); | |
dc877341 PZ |
495 | } |
496 | ||
fa9c9d10 WL |
497 | static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq); |
498 | ||
a649f237 | 499 | static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p) |
fa9c9d10 WL |
500 | { |
501 | struct rq *later_rq = NULL; | |
fa9c9d10 WL |
502 | |
503 | later_rq = find_lock_later_rq(p, rq); | |
fa9c9d10 WL |
504 | if (!later_rq) { |
505 | int cpu; | |
506 | ||
507 | /* | |
508 | * If we cannot preempt any rq, fall back to pick any | |
509 | * online cpu. | |
510 | */ | |
0c98d344 | 511 | cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed); |
fa9c9d10 WL |
512 | if (cpu >= nr_cpu_ids) { |
513 | /* | |
514 | * Fail to find any suitable cpu. | |
515 | * The task will never come back! | |
516 | */ | |
517 | BUG_ON(dl_bandwidth_enabled()); | |
518 | ||
519 | /* | |
520 | * If admission control is disabled we | |
521 | * try a little harder to let the task | |
522 | * run. | |
523 | */ | |
524 | cpu = cpumask_any(cpu_active_mask); | |
525 | } | |
526 | later_rq = cpu_rq(cpu); | |
527 | double_lock_balance(rq, later_rq); | |
528 | } | |
529 | ||
fa9c9d10 | 530 | set_task_cpu(p, later_rq->cpu); |
a649f237 PZ |
531 | double_unlock_balance(later_rq, rq); |
532 | ||
533 | return later_rq; | |
fa9c9d10 WL |
534 | } |
535 | ||
1baca4ce JL |
536 | #else |
537 | ||
538 | static inline | |
539 | void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p) | |
540 | { | |
541 | } | |
542 | ||
543 | static inline | |
544 | void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p) | |
545 | { | |
546 | } | |
547 | ||
548 | static inline | |
549 | void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
550 | { | |
551 | } | |
552 | ||
553 | static inline | |
554 | void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
555 | { | |
556 | } | |
557 | ||
dc877341 PZ |
558 | static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) |
559 | { | |
560 | return false; | |
561 | } | |
562 | ||
0ea60c20 | 563 | static inline void pull_dl_task(struct rq *rq) |
dc877341 | 564 | { |
dc877341 PZ |
565 | } |
566 | ||
e3fca9e7 | 567 | static inline void queue_push_tasks(struct rq *rq) |
dc877341 | 568 | { |
dc877341 PZ |
569 | } |
570 | ||
9916e214 | 571 | static inline void queue_pull_task(struct rq *rq) |
dc877341 PZ |
572 | { |
573 | } | |
1baca4ce JL |
574 | #endif /* CONFIG_SMP */ |
575 | ||
aab03e05 DF |
576 | static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags); |
577 | static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags); | |
578 | static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, | |
579 | int flags); | |
580 | ||
581 | /* | |
582 | * We are being explicitly informed that a new instance is starting, | |
583 | * and this means that: | |
584 | * - the absolute deadline of the entity has to be placed at | |
585 | * current time + relative deadline; | |
586 | * - the runtime of the entity has to be set to the maximum value. | |
587 | * | |
588 | * The capability of specifying such event is useful whenever a -deadline | |
589 | * entity wants to (try to!) synchronize its behaviour with the scheduler's | |
590 | * one, and to (try to!) reconcile itself with its own scheduling | |
591 | * parameters. | |
592 | */ | |
98b0a857 | 593 | static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) |
aab03e05 DF |
594 | { |
595 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
596 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
597 | ||
98b0a857 | 598 | WARN_ON(dl_se->dl_boosted); |
72f9f3fd LA |
599 | WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline)); |
600 | ||
601 | /* | |
602 | * We are racing with the deadline timer. So, do nothing because | |
603 | * the deadline timer handler will take care of properly recharging | |
604 | * the runtime and postponing the deadline | |
605 | */ | |
606 | if (dl_se->dl_throttled) | |
607 | return; | |
aab03e05 DF |
608 | |
609 | /* | |
610 | * We use the regular wall clock time to set deadlines in the | |
611 | * future; in fact, we must consider execution overheads (time | |
612 | * spent on hardirq context, etc.). | |
613 | */ | |
98b0a857 JL |
614 | dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline; |
615 | dl_se->runtime = dl_se->dl_runtime; | |
aab03e05 DF |
616 | } |
617 | ||
618 | /* | |
619 | * Pure Earliest Deadline First (EDF) scheduling does not deal with the | |
620 | * possibility of a entity lasting more than what it declared, and thus | |
621 | * exhausting its runtime. | |
622 | * | |
623 | * Here we are interested in making runtime overrun possible, but we do | |
624 | * not want a entity which is misbehaving to affect the scheduling of all | |
625 | * other entities. | |
626 | * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS) | |
627 | * is used, in order to confine each entity within its own bandwidth. | |
628 | * | |
629 | * This function deals exactly with that, and ensures that when the runtime | |
630 | * of a entity is replenished, its deadline is also postponed. That ensures | |
631 | * the overrunning entity can't interfere with other entity in the system and | |
632 | * can't make them miss their deadlines. Reasons why this kind of overruns | |
633 | * could happen are, typically, a entity voluntarily trying to overcome its | |
1b09d29b | 634 | * runtime, or it just underestimated it during sched_setattr(). |
aab03e05 | 635 | */ |
2d3d891d DF |
636 | static void replenish_dl_entity(struct sched_dl_entity *dl_se, |
637 | struct sched_dl_entity *pi_se) | |
aab03e05 DF |
638 | { |
639 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
640 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
641 | ||
2d3d891d DF |
642 | BUG_ON(pi_se->dl_runtime <= 0); |
643 | ||
644 | /* | |
645 | * This could be the case for a !-dl task that is boosted. | |
646 | * Just go with full inherited parameters. | |
647 | */ | |
648 | if (dl_se->dl_deadline == 0) { | |
649 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; | |
650 | dl_se->runtime = pi_se->dl_runtime; | |
651 | } | |
652 | ||
48be3a67 PZ |
653 | if (dl_se->dl_yielded && dl_se->runtime > 0) |
654 | dl_se->runtime = 0; | |
655 | ||
aab03e05 DF |
656 | /* |
657 | * We keep moving the deadline away until we get some | |
658 | * available runtime for the entity. This ensures correct | |
659 | * handling of situations where the runtime overrun is | |
660 | * arbitrary large. | |
661 | */ | |
662 | while (dl_se->runtime <= 0) { | |
2d3d891d DF |
663 | dl_se->deadline += pi_se->dl_period; |
664 | dl_se->runtime += pi_se->dl_runtime; | |
aab03e05 DF |
665 | } |
666 | ||
667 | /* | |
668 | * At this point, the deadline really should be "in | |
669 | * the future" with respect to rq->clock. If it's | |
670 | * not, we are, for some reason, lagging too much! | |
671 | * Anyway, after having warn userspace abut that, | |
672 | * we still try to keep the things running by | |
673 | * resetting the deadline and the budget of the | |
674 | * entity. | |
675 | */ | |
676 | if (dl_time_before(dl_se->deadline, rq_clock(rq))) { | |
c219b7dd | 677 | printk_deferred_once("sched: DL replenish lagged too much\n"); |
2d3d891d DF |
678 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; |
679 | dl_se->runtime = pi_se->dl_runtime; | |
aab03e05 | 680 | } |
1019a359 PZ |
681 | |
682 | if (dl_se->dl_yielded) | |
683 | dl_se->dl_yielded = 0; | |
684 | if (dl_se->dl_throttled) | |
685 | dl_se->dl_throttled = 0; | |
aab03e05 DF |
686 | } |
687 | ||
688 | /* | |
689 | * Here we check if --at time t-- an entity (which is probably being | |
690 | * [re]activated or, in general, enqueued) can use its remaining runtime | |
691 | * and its current deadline _without_ exceeding the bandwidth it is | |
692 | * assigned (function returns true if it can't). We are in fact applying | |
693 | * one of the CBS rules: when a task wakes up, if the residual runtime | |
694 | * over residual deadline fits within the allocated bandwidth, then we | |
695 | * can keep the current (absolute) deadline and residual budget without | |
696 | * disrupting the schedulability of the system. Otherwise, we should | |
697 | * refill the runtime and set the deadline a period in the future, | |
698 | * because keeping the current (absolute) deadline of the task would | |
712e5e34 DF |
699 | * result in breaking guarantees promised to other tasks (refer to |
700 | * Documentation/scheduler/sched-deadline.txt for more informations). | |
aab03e05 DF |
701 | * |
702 | * This function returns true if: | |
703 | * | |
2317d5f1 | 704 | * runtime / (deadline - t) > dl_runtime / dl_deadline , |
aab03e05 DF |
705 | * |
706 | * IOW we can't recycle current parameters. | |
755378a4 | 707 | * |
2317d5f1 | 708 | * Notice that the bandwidth check is done against the deadline. For |
755378a4 | 709 | * task with deadline equal to period this is the same of using |
2317d5f1 | 710 | * dl_period instead of dl_deadline in the equation above. |
aab03e05 | 711 | */ |
2d3d891d DF |
712 | static bool dl_entity_overflow(struct sched_dl_entity *dl_se, |
713 | struct sched_dl_entity *pi_se, u64 t) | |
aab03e05 DF |
714 | { |
715 | u64 left, right; | |
716 | ||
717 | /* | |
718 | * left and right are the two sides of the equation above, | |
719 | * after a bit of shuffling to use multiplications instead | |
720 | * of divisions. | |
721 | * | |
722 | * Note that none of the time values involved in the two | |
723 | * multiplications are absolute: dl_deadline and dl_runtime | |
724 | * are the relative deadline and the maximum runtime of each | |
725 | * instance, runtime is the runtime left for the last instance | |
726 | * and (deadline - t), since t is rq->clock, is the time left | |
727 | * to the (absolute) deadline. Even if overflowing the u64 type | |
728 | * is very unlikely to occur in both cases, here we scale down | |
729 | * as we want to avoid that risk at all. Scaling down by 10 | |
730 | * means that we reduce granularity to 1us. We are fine with it, | |
731 | * since this is only a true/false check and, anyway, thinking | |
732 | * of anything below microseconds resolution is actually fiction | |
733 | * (but still we want to give the user that illusion >;). | |
734 | */ | |
2317d5f1 | 735 | left = (pi_se->dl_deadline >> DL_SCALE) * (dl_se->runtime >> DL_SCALE); |
332ac17e DF |
736 | right = ((dl_se->deadline - t) >> DL_SCALE) * |
737 | (pi_se->dl_runtime >> DL_SCALE); | |
aab03e05 DF |
738 | |
739 | return dl_time_before(right, left); | |
740 | } | |
741 | ||
742 | /* | |
3effcb42 DBO |
743 | * Revised wakeup rule [1]: For self-suspending tasks, rather then |
744 | * re-initializing task's runtime and deadline, the revised wakeup | |
745 | * rule adjusts the task's runtime to avoid the task to overrun its | |
746 | * density. | |
aab03e05 | 747 | * |
3effcb42 DBO |
748 | * Reasoning: a task may overrun the density if: |
749 | * runtime / (deadline - t) > dl_runtime / dl_deadline | |
750 | * | |
751 | * Therefore, runtime can be adjusted to: | |
752 | * runtime = (dl_runtime / dl_deadline) * (deadline - t) | |
753 | * | |
754 | * In such way that runtime will be equal to the maximum density | |
755 | * the task can use without breaking any rule. | |
756 | * | |
757 | * [1] Luca Abeni, Giuseppe Lipari, and Juri Lelli. 2015. Constant | |
758 | * bandwidth server revisited. SIGBED Rev. 11, 4 (January 2015), 19-24. | |
759 | */ | |
760 | static void | |
761 | update_dl_revised_wakeup(struct sched_dl_entity *dl_se, struct rq *rq) | |
762 | { | |
763 | u64 laxity = dl_se->deadline - rq_clock(rq); | |
764 | ||
765 | /* | |
766 | * If the task has deadline < period, and the deadline is in the past, | |
767 | * it should already be throttled before this check. | |
768 | * | |
769 | * See update_dl_entity() comments for further details. | |
770 | */ | |
771 | WARN_ON(dl_time_before(dl_se->deadline, rq_clock(rq))); | |
772 | ||
773 | dl_se->runtime = (dl_se->dl_density * laxity) >> BW_SHIFT; | |
774 | } | |
775 | ||
776 | /* | |
777 | * Regarding the deadline, a task with implicit deadline has a relative | |
778 | * deadline == relative period. A task with constrained deadline has a | |
779 | * relative deadline <= relative period. | |
780 | * | |
781 | * We support constrained deadline tasks. However, there are some restrictions | |
782 | * applied only for tasks which do not have an implicit deadline. See | |
783 | * update_dl_entity() to know more about such restrictions. | |
784 | * | |
785 | * The dl_is_implicit() returns true if the task has an implicit deadline. | |
786 | */ | |
787 | static inline bool dl_is_implicit(struct sched_dl_entity *dl_se) | |
788 | { | |
789 | return dl_se->dl_deadline == dl_se->dl_period; | |
790 | } | |
791 | ||
792 | /* | |
793 | * When a deadline entity is placed in the runqueue, its runtime and deadline | |
794 | * might need to be updated. This is done by a CBS wake up rule. There are two | |
795 | * different rules: 1) the original CBS; and 2) the Revisited CBS. | |
796 | * | |
797 | * When the task is starting a new period, the Original CBS is used. In this | |
798 | * case, the runtime is replenished and a new absolute deadline is set. | |
799 | * | |
800 | * When a task is queued before the begin of the next period, using the | |
801 | * remaining runtime and deadline could make the entity to overflow, see | |
802 | * dl_entity_overflow() to find more about runtime overflow. When such case | |
803 | * is detected, the runtime and deadline need to be updated. | |
804 | * | |
805 | * If the task has an implicit deadline, i.e., deadline == period, the Original | |
806 | * CBS is applied. the runtime is replenished and a new absolute deadline is | |
807 | * set, as in the previous cases. | |
808 | * | |
809 | * However, the Original CBS does not work properly for tasks with | |
810 | * deadline < period, which are said to have a constrained deadline. By | |
811 | * applying the Original CBS, a constrained deadline task would be able to run | |
812 | * runtime/deadline in a period. With deadline < period, the task would | |
813 | * overrun the runtime/period allowed bandwidth, breaking the admission test. | |
814 | * | |
815 | * In order to prevent this misbehave, the Revisited CBS is used for | |
816 | * constrained deadline tasks when a runtime overflow is detected. In the | |
817 | * Revisited CBS, rather than replenishing & setting a new absolute deadline, | |
818 | * the remaining runtime of the task is reduced to avoid runtime overflow. | |
819 | * Please refer to the comments update_dl_revised_wakeup() function to find | |
820 | * more about the Revised CBS rule. | |
aab03e05 | 821 | */ |
2d3d891d DF |
822 | static void update_dl_entity(struct sched_dl_entity *dl_se, |
823 | struct sched_dl_entity *pi_se) | |
aab03e05 DF |
824 | { |
825 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
826 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
827 | ||
aab03e05 | 828 | if (dl_time_before(dl_se->deadline, rq_clock(rq)) || |
2d3d891d | 829 | dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) { |
3effcb42 DBO |
830 | |
831 | if (unlikely(!dl_is_implicit(dl_se) && | |
832 | !dl_time_before(dl_se->deadline, rq_clock(rq)) && | |
833 | !dl_se->dl_boosted)){ | |
834 | update_dl_revised_wakeup(dl_se, rq); | |
835 | return; | |
836 | } | |
837 | ||
2d3d891d DF |
838 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; |
839 | dl_se->runtime = pi_se->dl_runtime; | |
aab03e05 DF |
840 | } |
841 | } | |
842 | ||
5ac69d37 DBO |
843 | static inline u64 dl_next_period(struct sched_dl_entity *dl_se) |
844 | { | |
845 | return dl_se->deadline - dl_se->dl_deadline + dl_se->dl_period; | |
846 | } | |
847 | ||
aab03e05 DF |
848 | /* |
849 | * If the entity depleted all its runtime, and if we want it to sleep | |
850 | * while waiting for some new execution time to become available, we | |
5ac69d37 | 851 | * set the bandwidth replenishment timer to the replenishment instant |
aab03e05 DF |
852 | * and try to activate it. |
853 | * | |
854 | * Notice that it is important for the caller to know if the timer | |
855 | * actually started or not (i.e., the replenishment instant is in | |
856 | * the future or in the past). | |
857 | */ | |
a649f237 | 858 | static int start_dl_timer(struct task_struct *p) |
aab03e05 | 859 | { |
a649f237 PZ |
860 | struct sched_dl_entity *dl_se = &p->dl; |
861 | struct hrtimer *timer = &dl_se->dl_timer; | |
862 | struct rq *rq = task_rq(p); | |
aab03e05 | 863 | ktime_t now, act; |
aab03e05 DF |
864 | s64 delta; |
865 | ||
a649f237 PZ |
866 | lockdep_assert_held(&rq->lock); |
867 | ||
aab03e05 DF |
868 | /* |
869 | * We want the timer to fire at the deadline, but considering | |
870 | * that it is actually coming from rq->clock and not from | |
871 | * hrtimer's time base reading. | |
872 | */ | |
5ac69d37 | 873 | act = ns_to_ktime(dl_next_period(dl_se)); |
a649f237 | 874 | now = hrtimer_cb_get_time(timer); |
aab03e05 DF |
875 | delta = ktime_to_ns(now) - rq_clock(rq); |
876 | act = ktime_add_ns(act, delta); | |
877 | ||
878 | /* | |
879 | * If the expiry time already passed, e.g., because the value | |
880 | * chosen as the deadline is too small, don't even try to | |
881 | * start the timer in the past! | |
882 | */ | |
883 | if (ktime_us_delta(act, now) < 0) | |
884 | return 0; | |
885 | ||
a649f237 PZ |
886 | /* |
887 | * !enqueued will guarantee another callback; even if one is already in | |
888 | * progress. This ensures a balanced {get,put}_task_struct(). | |
889 | * | |
890 | * The race against __run_timer() clearing the enqueued state is | |
891 | * harmless because we're holding task_rq()->lock, therefore the timer | |
892 | * expiring after we've done the check will wait on its task_rq_lock() | |
893 | * and observe our state. | |
894 | */ | |
895 | if (!hrtimer_is_queued(timer)) { | |
896 | get_task_struct(p); | |
897 | hrtimer_start(timer, act, HRTIMER_MODE_ABS); | |
898 | } | |
aab03e05 | 899 | |
cc9684d3 | 900 | return 1; |
aab03e05 DF |
901 | } |
902 | ||
903 | /* | |
904 | * This is the bandwidth enforcement timer callback. If here, we know | |
905 | * a task is not on its dl_rq, since the fact that the timer was running | |
906 | * means the task is throttled and needs a runtime replenishment. | |
907 | * | |
908 | * However, what we actually do depends on the fact the task is active, | |
909 | * (it is on its rq) or has been removed from there by a call to | |
910 | * dequeue_task_dl(). In the former case we must issue the runtime | |
911 | * replenishment and add the task back to the dl_rq; in the latter, we just | |
912 | * do nothing but clearing dl_throttled, so that runtime and deadline | |
913 | * updating (and the queueing back to dl_rq) will be done by the | |
914 | * next call to enqueue_task_dl(). | |
915 | */ | |
916 | static enum hrtimer_restart dl_task_timer(struct hrtimer *timer) | |
917 | { | |
918 | struct sched_dl_entity *dl_se = container_of(timer, | |
919 | struct sched_dl_entity, | |
920 | dl_timer); | |
921 | struct task_struct *p = dl_task_of(dl_se); | |
eb580751 | 922 | struct rq_flags rf; |
0f397f2c | 923 | struct rq *rq; |
3960c8c0 | 924 | |
eb580751 | 925 | rq = task_rq_lock(p, &rf); |
0f397f2c | 926 | |
aab03e05 | 927 | /* |
a649f237 | 928 | * The task might have changed its scheduling policy to something |
9846d50d | 929 | * different than SCHED_DEADLINE (through switched_from_dl()). |
a649f237 | 930 | */ |
209a0cbd | 931 | if (!dl_task(p)) |
a649f237 | 932 | goto unlock; |
a649f237 | 933 | |
a649f237 PZ |
934 | /* |
935 | * The task might have been boosted by someone else and might be in the | |
936 | * boosting/deboosting path, its not throttled. | |
937 | */ | |
938 | if (dl_se->dl_boosted) | |
939 | goto unlock; | |
a79ec89f | 940 | |
fa9c9d10 | 941 | /* |
a649f237 PZ |
942 | * Spurious timer due to start_dl_timer() race; or we already received |
943 | * a replenishment from rt_mutex_setprio(). | |
fa9c9d10 | 944 | */ |
a649f237 | 945 | if (!dl_se->dl_throttled) |
fa9c9d10 | 946 | goto unlock; |
a649f237 PZ |
947 | |
948 | sched_clock_tick(); | |
949 | update_rq_clock(rq); | |
fa9c9d10 | 950 | |
a79ec89f KT |
951 | /* |
952 | * If the throttle happened during sched-out; like: | |
953 | * | |
954 | * schedule() | |
955 | * deactivate_task() | |
956 | * dequeue_task_dl() | |
957 | * update_curr_dl() | |
958 | * start_dl_timer() | |
959 | * __dequeue_task_dl() | |
960 | * prev->on_rq = 0; | |
961 | * | |
962 | * We can be both throttled and !queued. Replenish the counter | |
963 | * but do not enqueue -- wait for our wakeup to do that. | |
964 | */ | |
965 | if (!task_on_rq_queued(p)) { | |
966 | replenish_dl_entity(dl_se, dl_se); | |
967 | goto unlock; | |
968 | } | |
969 | ||
1baca4ce | 970 | #ifdef CONFIG_SMP |
c0c8c9fa | 971 | if (unlikely(!rq->online)) { |
61c7aca6 WL |
972 | /* |
973 | * If the runqueue is no longer available, migrate the | |
974 | * task elsewhere. This necessarily changes rq. | |
975 | */ | |
c0c8c9fa | 976 | lockdep_unpin_lock(&rq->lock, rf.cookie); |
a649f237 | 977 | rq = dl_task_offline_migration(rq, p); |
c0c8c9fa | 978 | rf.cookie = lockdep_pin_lock(&rq->lock); |
dcc3b5ff | 979 | update_rq_clock(rq); |
61c7aca6 WL |
980 | |
981 | /* | |
982 | * Now that the task has been migrated to the new RQ and we | |
983 | * have that locked, proceed as normal and enqueue the task | |
984 | * there. | |
985 | */ | |
c0c8c9fa | 986 | } |
61c7aca6 | 987 | #endif |
a649f237 | 988 | |
61c7aca6 WL |
989 | enqueue_task_dl(rq, p, ENQUEUE_REPLENISH); |
990 | if (dl_task(rq->curr)) | |
991 | check_preempt_curr_dl(rq, p, 0); | |
992 | else | |
993 | resched_curr(rq); | |
a649f237 | 994 | |
61c7aca6 | 995 | #ifdef CONFIG_SMP |
a649f237 PZ |
996 | /* |
997 | * Queueing this task back might have overloaded rq, check if we need | |
998 | * to kick someone away. | |
1019a359 | 999 | */ |
0aaafaab PZ |
1000 | if (has_pushable_dl_tasks(rq)) { |
1001 | /* | |
1002 | * Nothing relies on rq->lock after this, so its safe to drop | |
1003 | * rq->lock. | |
1004 | */ | |
d8ac8971 | 1005 | rq_unpin_lock(rq, &rf); |
1019a359 | 1006 | push_dl_task(rq); |
d8ac8971 | 1007 | rq_repin_lock(rq, &rf); |
0aaafaab | 1008 | } |
1baca4ce | 1009 | #endif |
a649f237 | 1010 | |
aab03e05 | 1011 | unlock: |
eb580751 | 1012 | task_rq_unlock(rq, p, &rf); |
aab03e05 | 1013 | |
a649f237 PZ |
1014 | /* |
1015 | * This can free the task_struct, including this hrtimer, do not touch | |
1016 | * anything related to that after this. | |
1017 | */ | |
1018 | put_task_struct(p); | |
1019 | ||
aab03e05 DF |
1020 | return HRTIMER_NORESTART; |
1021 | } | |
1022 | ||
1023 | void init_dl_task_timer(struct sched_dl_entity *dl_se) | |
1024 | { | |
1025 | struct hrtimer *timer = &dl_se->dl_timer; | |
1026 | ||
aab03e05 DF |
1027 | hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
1028 | timer->function = dl_task_timer; | |
1029 | } | |
1030 | ||
df8eac8c DBO |
1031 | /* |
1032 | * During the activation, CBS checks if it can reuse the current task's | |
1033 | * runtime and period. If the deadline of the task is in the past, CBS | |
1034 | * cannot use the runtime, and so it replenishes the task. This rule | |
1035 | * works fine for implicit deadline tasks (deadline == period), and the | |
1036 | * CBS was designed for implicit deadline tasks. However, a task with | |
1037 | * constrained deadline (deadine < period) might be awakened after the | |
1038 | * deadline, but before the next period. In this case, replenishing the | |
1039 | * task would allow it to run for runtime / deadline. As in this case | |
1040 | * deadline < period, CBS enables a task to run for more than the | |
1041 | * runtime / period. In a very loaded system, this can cause a domino | |
1042 | * effect, making other tasks miss their deadlines. | |
1043 | * | |
1044 | * To avoid this problem, in the activation of a constrained deadline | |
1045 | * task after the deadline but before the next period, throttle the | |
1046 | * task and set the replenishing timer to the begin of the next period, | |
1047 | * unless it is boosted. | |
1048 | */ | |
1049 | static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se) | |
1050 | { | |
1051 | struct task_struct *p = dl_task_of(dl_se); | |
1052 | struct rq *rq = rq_of_dl_rq(dl_rq_of_se(dl_se)); | |
1053 | ||
1054 | if (dl_time_before(dl_se->deadline, rq_clock(rq)) && | |
1055 | dl_time_before(rq_clock(rq), dl_next_period(dl_se))) { | |
1056 | if (unlikely(dl_se->dl_boosted || !start_dl_timer(p))) | |
1057 | return; | |
1058 | dl_se->dl_throttled = 1; | |
ae83b56a XP |
1059 | if (dl_se->runtime > 0) |
1060 | dl_se->runtime = 0; | |
df8eac8c DBO |
1061 | } |
1062 | } | |
1063 | ||
aab03e05 | 1064 | static |
6fab5410 | 1065 | int dl_runtime_exceeded(struct sched_dl_entity *dl_se) |
aab03e05 | 1066 | { |
269ad801 | 1067 | return (dl_se->runtime <= 0); |
aab03e05 DF |
1068 | } |
1069 | ||
faa59937 JL |
1070 | extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq); |
1071 | ||
c52f14d3 LA |
1072 | /* |
1073 | * This function implements the GRUB accounting rule: | |
1074 | * according to the GRUB reclaiming algorithm, the runtime is | |
daec5798 LA |
1075 | * not decreased as "dq = -dt", but as |
1076 | * "dq = -max{u / Umax, (1 - Uinact - Uextra)} dt", | |
1077 | * where u is the utilization of the task, Umax is the maximum reclaimable | |
1078 | * utilization, Uinact is the (per-runqueue) inactive utilization, computed | |
1079 | * as the difference between the "total runqueue utilization" and the | |
1080 | * runqueue active utilization, and Uextra is the (per runqueue) extra | |
1081 | * reclaimable utilization. | |
9f0d1a50 | 1082 | * Since rq->dl.running_bw and rq->dl.this_bw contain utilizations |
daec5798 LA |
1083 | * multiplied by 2^BW_SHIFT, the result has to be shifted right by |
1084 | * BW_SHIFT. | |
1085 | * Since rq->dl.bw_ratio contains 1 / Umax multipled by 2^RATIO_SHIFT, | |
1086 | * dl_bw is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT. | |
1087 | * Since delta is a 64 bit variable, to have an overflow its value | |
1088 | * should be larger than 2^(64 - 20 - 8), which is more than 64 seconds. | |
1089 | * So, overflow is not an issue here. | |
c52f14d3 | 1090 | */ |
9f0d1a50 | 1091 | u64 grub_reclaim(u64 delta, struct rq *rq, struct sched_dl_entity *dl_se) |
c52f14d3 | 1092 | { |
9f0d1a50 LA |
1093 | u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */ |
1094 | u64 u_act; | |
daec5798 | 1095 | u64 u_act_min = (dl_se->dl_bw * rq->dl.bw_ratio) >> RATIO_SHIFT; |
c52f14d3 | 1096 | |
9f0d1a50 | 1097 | /* |
daec5798 LA |
1098 | * Instead of computing max{u * bw_ratio, (1 - u_inact - u_extra)}, |
1099 | * we compare u_inact + rq->dl.extra_bw with | |
1100 | * 1 - (u * rq->dl.bw_ratio >> RATIO_SHIFT), because | |
1101 | * u_inact + rq->dl.extra_bw can be larger than | |
1102 | * 1 * (so, 1 - u_inact - rq->dl.extra_bw would be negative | |
1103 | * leading to wrong results) | |
9f0d1a50 | 1104 | */ |
daec5798 LA |
1105 | if (u_inact + rq->dl.extra_bw > BW_UNIT - u_act_min) |
1106 | u_act = u_act_min; | |
9f0d1a50 | 1107 | else |
daec5798 | 1108 | u_act = BW_UNIT - u_inact - rq->dl.extra_bw; |
9f0d1a50 LA |
1109 | |
1110 | return (delta * u_act) >> BW_SHIFT; | |
c52f14d3 LA |
1111 | } |
1112 | ||
aab03e05 DF |
1113 | /* |
1114 | * Update the current task's runtime statistics (provided it is still | |
1115 | * a -deadline task and has not been removed from the dl_rq). | |
1116 | */ | |
1117 | static void update_curr_dl(struct rq *rq) | |
1118 | { | |
1119 | struct task_struct *curr = rq->curr; | |
1120 | struct sched_dl_entity *dl_se = &curr->dl; | |
1121 | u64 delta_exec; | |
1122 | ||
1123 | if (!dl_task(curr) || !on_dl_rq(dl_se)) | |
1124 | return; | |
1125 | ||
1126 | /* | |
1127 | * Consumed budget is computed considering the time as | |
1128 | * observed by schedulable tasks (excluding time spent | |
1129 | * in hardirq context, etc.). Deadlines are instead | |
1130 | * computed using hard walltime. This seems to be the more | |
1131 | * natural solution, but the full ramifications of this | |
1132 | * approach need further study. | |
1133 | */ | |
1134 | delta_exec = rq_clock_task(rq) - curr->se.exec_start; | |
48be3a67 PZ |
1135 | if (unlikely((s64)delta_exec <= 0)) { |
1136 | if (unlikely(dl_se->dl_yielded)) | |
1137 | goto throttle; | |
734ff2a7 | 1138 | return; |
48be3a67 | 1139 | } |
aab03e05 DF |
1140 | |
1141 | schedstat_set(curr->se.statistics.exec_max, | |
1142 | max(curr->se.statistics.exec_max, delta_exec)); | |
1143 | ||
1144 | curr->se.sum_exec_runtime += delta_exec; | |
1145 | account_group_exec_runtime(curr, delta_exec); | |
1146 | ||
1147 | curr->se.exec_start = rq_clock_task(rq); | |
d2cc5ed6 | 1148 | cgroup_account_cputime(curr, delta_exec); |
aab03e05 | 1149 | |
239be4a9 DF |
1150 | sched_rt_avg_update(rq, delta_exec); |
1151 | ||
2d4283e9 | 1152 | if (unlikely(dl_se->flags & SCHED_FLAG_RECLAIM)) |
9f0d1a50 | 1153 | delta_exec = grub_reclaim(delta_exec, rq, &curr->dl); |
48be3a67 PZ |
1154 | dl_se->runtime -= delta_exec; |
1155 | ||
1156 | throttle: | |
1157 | if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) { | |
1019a359 | 1158 | dl_se->dl_throttled = 1; |
34be3930 JL |
1159 | |
1160 | /* If requested, inform the user about runtime overruns. */ | |
1161 | if (dl_runtime_exceeded(dl_se) && | |
1162 | (dl_se->flags & SCHED_FLAG_DL_OVERRUN)) | |
1163 | dl_se->dl_overrun = 1; | |
1164 | ||
aab03e05 | 1165 | __dequeue_task_dl(rq, curr, 0); |
a649f237 | 1166 | if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr))) |
aab03e05 DF |
1167 | enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH); |
1168 | ||
1169 | if (!is_leftmost(curr, &rq->dl)) | |
8875125e | 1170 | resched_curr(rq); |
aab03e05 | 1171 | } |
1724813d PZ |
1172 | |
1173 | /* | |
1174 | * Because -- for now -- we share the rt bandwidth, we need to | |
1175 | * account our runtime there too, otherwise actual rt tasks | |
1176 | * would be able to exceed the shared quota. | |
1177 | * | |
1178 | * Account to the root rt group for now. | |
1179 | * | |
1180 | * The solution we're working towards is having the RT groups scheduled | |
1181 | * using deadline servers -- however there's a few nasties to figure | |
1182 | * out before that can happen. | |
1183 | */ | |
1184 | if (rt_bandwidth_enabled()) { | |
1185 | struct rt_rq *rt_rq = &rq->rt; | |
1186 | ||
1187 | raw_spin_lock(&rt_rq->rt_runtime_lock); | |
1724813d PZ |
1188 | /* |
1189 | * We'll let actual RT tasks worry about the overflow here, we | |
faa59937 JL |
1190 | * have our own CBS to keep us inline; only account when RT |
1191 | * bandwidth is relevant. | |
1724813d | 1192 | */ |
faa59937 JL |
1193 | if (sched_rt_bandwidth_account(rt_rq)) |
1194 | rt_rq->rt_time += delta_exec; | |
1724813d PZ |
1195 | raw_spin_unlock(&rt_rq->rt_runtime_lock); |
1196 | } | |
aab03e05 DF |
1197 | } |
1198 | ||
209a0cbd LA |
1199 | static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer) |
1200 | { | |
1201 | struct sched_dl_entity *dl_se = container_of(timer, | |
1202 | struct sched_dl_entity, | |
1203 | inactive_timer); | |
1204 | struct task_struct *p = dl_task_of(dl_se); | |
1205 | struct rq_flags rf; | |
1206 | struct rq *rq; | |
1207 | ||
1208 | rq = task_rq_lock(p, &rf); | |
1209 | ||
1210 | if (!dl_task(p) || p->state == TASK_DEAD) { | |
387e3130 LA |
1211 | struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); |
1212 | ||
209a0cbd LA |
1213 | if (p->state == TASK_DEAD && dl_se->dl_non_contending) { |
1214 | sub_running_bw(p->dl.dl_bw, dl_rq_of_se(&p->dl)); | |
8fd27231 | 1215 | sub_rq_bw(p->dl.dl_bw, dl_rq_of_se(&p->dl)); |
209a0cbd LA |
1216 | dl_se->dl_non_contending = 0; |
1217 | } | |
387e3130 LA |
1218 | |
1219 | raw_spin_lock(&dl_b->lock); | |
8c0944ce | 1220 | __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p))); |
387e3130 | 1221 | raw_spin_unlock(&dl_b->lock); |
209a0cbd LA |
1222 | __dl_clear_params(p); |
1223 | ||
1224 | goto unlock; | |
1225 | } | |
1226 | if (dl_se->dl_non_contending == 0) | |
1227 | goto unlock; | |
1228 | ||
1229 | sched_clock_tick(); | |
1230 | update_rq_clock(rq); | |
1231 | ||
1232 | sub_running_bw(dl_se->dl_bw, &rq->dl); | |
1233 | dl_se->dl_non_contending = 0; | |
1234 | unlock: | |
1235 | task_rq_unlock(rq, p, &rf); | |
1236 | put_task_struct(p); | |
1237 | ||
1238 | return HRTIMER_NORESTART; | |
1239 | } | |
1240 | ||
1241 | void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se) | |
1242 | { | |
1243 | struct hrtimer *timer = &dl_se->inactive_timer; | |
1244 | ||
1245 | hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
1246 | timer->function = inactive_task_timer; | |
1247 | } | |
1248 | ||
1baca4ce JL |
1249 | #ifdef CONFIG_SMP |
1250 | ||
1baca4ce JL |
1251 | static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) |
1252 | { | |
1253 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
1254 | ||
1255 | if (dl_rq->earliest_dl.curr == 0 || | |
1256 | dl_time_before(deadline, dl_rq->earliest_dl.curr)) { | |
1baca4ce | 1257 | dl_rq->earliest_dl.curr = deadline; |
d8206bb3 | 1258 | cpudl_set(&rq->rd->cpudl, rq->cpu, deadline); |
1baca4ce JL |
1259 | } |
1260 | } | |
1261 | ||
1262 | static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) | |
1263 | { | |
1264 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
1265 | ||
1266 | /* | |
1267 | * Since we may have removed our earliest (and/or next earliest) | |
1268 | * task we must recompute them. | |
1269 | */ | |
1270 | if (!dl_rq->dl_nr_running) { | |
1271 | dl_rq->earliest_dl.curr = 0; | |
1272 | dl_rq->earliest_dl.next = 0; | |
d8206bb3 | 1273 | cpudl_clear(&rq->rd->cpudl, rq->cpu); |
1baca4ce | 1274 | } else { |
2161573e | 1275 | struct rb_node *leftmost = dl_rq->root.rb_leftmost; |
1baca4ce JL |
1276 | struct sched_dl_entity *entry; |
1277 | ||
1278 | entry = rb_entry(leftmost, struct sched_dl_entity, rb_node); | |
1279 | dl_rq->earliest_dl.curr = entry->deadline; | |
d8206bb3 | 1280 | cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline); |
1baca4ce JL |
1281 | } |
1282 | } | |
1283 | ||
1284 | #else | |
1285 | ||
1286 | static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {} | |
1287 | static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {} | |
1288 | ||
1289 | #endif /* CONFIG_SMP */ | |
1290 | ||
1291 | static inline | |
1292 | void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
1293 | { | |
1294 | int prio = dl_task_of(dl_se)->prio; | |
1295 | u64 deadline = dl_se->deadline; | |
1296 | ||
1297 | WARN_ON(!dl_prio(prio)); | |
1298 | dl_rq->dl_nr_running++; | |
72465447 | 1299 | add_nr_running(rq_of_dl_rq(dl_rq), 1); |
1baca4ce JL |
1300 | |
1301 | inc_dl_deadline(dl_rq, deadline); | |
1302 | inc_dl_migration(dl_se, dl_rq); | |
1303 | } | |
1304 | ||
1305 | static inline | |
1306 | void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
1307 | { | |
1308 | int prio = dl_task_of(dl_se)->prio; | |
1309 | ||
1310 | WARN_ON(!dl_prio(prio)); | |
1311 | WARN_ON(!dl_rq->dl_nr_running); | |
1312 | dl_rq->dl_nr_running--; | |
72465447 | 1313 | sub_nr_running(rq_of_dl_rq(dl_rq), 1); |
1baca4ce JL |
1314 | |
1315 | dec_dl_deadline(dl_rq, dl_se->deadline); | |
1316 | dec_dl_migration(dl_se, dl_rq); | |
1317 | } | |
1318 | ||
aab03e05 DF |
1319 | static void __enqueue_dl_entity(struct sched_dl_entity *dl_se) |
1320 | { | |
1321 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
2161573e | 1322 | struct rb_node **link = &dl_rq->root.rb_root.rb_node; |
aab03e05 DF |
1323 | struct rb_node *parent = NULL; |
1324 | struct sched_dl_entity *entry; | |
1325 | int leftmost = 1; | |
1326 | ||
1327 | BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node)); | |
1328 | ||
1329 | while (*link) { | |
1330 | parent = *link; | |
1331 | entry = rb_entry(parent, struct sched_dl_entity, rb_node); | |
1332 | if (dl_time_before(dl_se->deadline, entry->deadline)) | |
1333 | link = &parent->rb_left; | |
1334 | else { | |
1335 | link = &parent->rb_right; | |
1336 | leftmost = 0; | |
1337 | } | |
1338 | } | |
1339 | ||
aab03e05 | 1340 | rb_link_node(&dl_se->rb_node, parent, link); |
2161573e | 1341 | rb_insert_color_cached(&dl_se->rb_node, &dl_rq->root, leftmost); |
aab03e05 | 1342 | |
1baca4ce | 1343 | inc_dl_tasks(dl_se, dl_rq); |
aab03e05 DF |
1344 | } |
1345 | ||
1346 | static void __dequeue_dl_entity(struct sched_dl_entity *dl_se) | |
1347 | { | |
1348 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
1349 | ||
1350 | if (RB_EMPTY_NODE(&dl_se->rb_node)) | |
1351 | return; | |
1352 | ||
2161573e | 1353 | rb_erase_cached(&dl_se->rb_node, &dl_rq->root); |
aab03e05 DF |
1354 | RB_CLEAR_NODE(&dl_se->rb_node); |
1355 | ||
1baca4ce | 1356 | dec_dl_tasks(dl_se, dl_rq); |
aab03e05 DF |
1357 | } |
1358 | ||
1359 | static void | |
2d3d891d DF |
1360 | enqueue_dl_entity(struct sched_dl_entity *dl_se, |
1361 | struct sched_dl_entity *pi_se, int flags) | |
aab03e05 DF |
1362 | { |
1363 | BUG_ON(on_dl_rq(dl_se)); | |
1364 | ||
1365 | /* | |
1366 | * If this is a wakeup or a new instance, the scheduling | |
1367 | * parameters of the task might need updating. Otherwise, | |
1368 | * we want a replenishment of its runtime. | |
1369 | */ | |
e36d8677 | 1370 | if (flags & ENQUEUE_WAKEUP) { |
8fd27231 | 1371 | task_contending(dl_se, flags); |
2d3d891d | 1372 | update_dl_entity(dl_se, pi_se); |
e36d8677 | 1373 | } else if (flags & ENQUEUE_REPLENISH) { |
6a503c3b | 1374 | replenish_dl_entity(dl_se, pi_se); |
295d6d5e LA |
1375 | } else if ((flags & ENQUEUE_RESTORE) && |
1376 | dl_time_before(dl_se->deadline, | |
1377 | rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) { | |
1378 | setup_new_dl_entity(dl_se); | |
e36d8677 | 1379 | } |
aab03e05 DF |
1380 | |
1381 | __enqueue_dl_entity(dl_se); | |
1382 | } | |
1383 | ||
1384 | static void dequeue_dl_entity(struct sched_dl_entity *dl_se) | |
1385 | { | |
1386 | __dequeue_dl_entity(dl_se); | |
1387 | } | |
1388 | ||
1389 | static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) | |
1390 | { | |
2d3d891d DF |
1391 | struct task_struct *pi_task = rt_mutex_get_top_task(p); |
1392 | struct sched_dl_entity *pi_se = &p->dl; | |
1393 | ||
1394 | /* | |
193be41e JF |
1395 | * Use the scheduling parameters of the top pi-waiter task if: |
1396 | * - we have a top pi-waiter which is a SCHED_DEADLINE task AND | |
1397 | * - our dl_boosted is set (i.e. the pi-waiter's (absolute) deadline is | |
1398 | * smaller than our deadline OR we are a !SCHED_DEADLINE task getting | |
1399 | * boosted due to a SCHED_DEADLINE pi-waiter). | |
1400 | * Otherwise we keep our runtime and deadline. | |
2d3d891d | 1401 | */ |
193be41e | 1402 | if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) { |
2d3d891d | 1403 | pi_se = &pi_task->dl; |
64be6f1f JL |
1404 | } else if (!dl_prio(p->normal_prio)) { |
1405 | /* | |
1406 | * Special case in which we have a !SCHED_DEADLINE task | |
193be41e | 1407 | * that is going to be deboosted, but exceeds its |
64be6f1f JL |
1408 | * runtime while doing so. No point in replenishing |
1409 | * it, as it's going to return back to its original | |
1410 | * scheduling class after this. | |
1411 | */ | |
1412 | BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH); | |
1413 | return; | |
1414 | } | |
2d3d891d | 1415 | |
df8eac8c DBO |
1416 | /* |
1417 | * Check if a constrained deadline task was activated | |
1418 | * after the deadline but before the next period. | |
1419 | * If that is the case, the task will be throttled and | |
1420 | * the replenishment timer will be set to the next period. | |
1421 | */ | |
3effcb42 | 1422 | if (!p->dl.dl_throttled && !dl_is_implicit(&p->dl)) |
df8eac8c DBO |
1423 | dl_check_constrained_dl(&p->dl); |
1424 | ||
8fd27231 LA |
1425 | if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & ENQUEUE_RESTORE) { |
1426 | add_rq_bw(p->dl.dl_bw, &rq->dl); | |
e36d8677 | 1427 | add_running_bw(p->dl.dl_bw, &rq->dl); |
8fd27231 | 1428 | } |
e36d8677 | 1429 | |
aab03e05 | 1430 | /* |
e36d8677 | 1431 | * If p is throttled, we do not enqueue it. In fact, if it exhausted |
aab03e05 DF |
1432 | * its budget it needs a replenishment and, since it now is on |
1433 | * its rq, the bandwidth timer callback (which clearly has not | |
1434 | * run yet) will take care of this. | |
e36d8677 LA |
1435 | * However, the active utilization does not depend on the fact |
1436 | * that the task is on the runqueue or not (but depends on the | |
1437 | * task's state - in GRUB parlance, "inactive" vs "active contending"). | |
1438 | * In other words, even if a task is throttled its utilization must | |
1439 | * be counted in the active utilization; hence, we need to call | |
1440 | * add_running_bw(). | |
aab03e05 | 1441 | */ |
e36d8677 | 1442 | if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH)) { |
209a0cbd | 1443 | if (flags & ENQUEUE_WAKEUP) |
8fd27231 | 1444 | task_contending(&p->dl, flags); |
209a0cbd | 1445 | |
aab03e05 | 1446 | return; |
e36d8677 | 1447 | } |
aab03e05 | 1448 | |
2d3d891d | 1449 | enqueue_dl_entity(&p->dl, pi_se, flags); |
1baca4ce | 1450 | |
4b53a341 | 1451 | if (!task_current(rq, p) && p->nr_cpus_allowed > 1) |
1baca4ce | 1452 | enqueue_pushable_dl_task(rq, p); |
aab03e05 DF |
1453 | } |
1454 | ||
1455 | static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) | |
1456 | { | |
1457 | dequeue_dl_entity(&p->dl); | |
1baca4ce | 1458 | dequeue_pushable_dl_task(rq, p); |
aab03e05 DF |
1459 | } |
1460 | ||
1461 | static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) | |
1462 | { | |
1463 | update_curr_dl(rq); | |
1464 | __dequeue_task_dl(rq, p, flags); | |
e36d8677 | 1465 | |
8fd27231 | 1466 | if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & DEQUEUE_SAVE) { |
e36d8677 | 1467 | sub_running_bw(p->dl.dl_bw, &rq->dl); |
8fd27231 LA |
1468 | sub_rq_bw(p->dl.dl_bw, &rq->dl); |
1469 | } | |
e36d8677 LA |
1470 | |
1471 | /* | |
209a0cbd LA |
1472 | * This check allows to start the inactive timer (or to immediately |
1473 | * decrease the active utilization, if needed) in two cases: | |
e36d8677 LA |
1474 | * when the task blocks and when it is terminating |
1475 | * (p->state == TASK_DEAD). We can handle the two cases in the same | |
1476 | * way, because from GRUB's point of view the same thing is happening | |
1477 | * (the task moves from "active contending" to "active non contending" | |
1478 | * or "inactive") | |
1479 | */ | |
1480 | if (flags & DEQUEUE_SLEEP) | |
209a0cbd | 1481 | task_non_contending(p); |
aab03e05 DF |
1482 | } |
1483 | ||
1484 | /* | |
1485 | * Yield task semantic for -deadline tasks is: | |
1486 | * | |
1487 | * get off from the CPU until our next instance, with | |
1488 | * a new runtime. This is of little use now, since we | |
1489 | * don't have a bandwidth reclaiming mechanism. Anyway, | |
1490 | * bandwidth reclaiming is planned for the future, and | |
1491 | * yield_task_dl will indicate that some spare budget | |
1492 | * is available for other task instances to use it. | |
1493 | */ | |
1494 | static void yield_task_dl(struct rq *rq) | |
1495 | { | |
aab03e05 DF |
1496 | /* |
1497 | * We make the task go to sleep until its current deadline by | |
1498 | * forcing its runtime to zero. This way, update_curr_dl() stops | |
1499 | * it and the bandwidth timer will wake it up and will give it | |
5bfd126e | 1500 | * new scheduling parameters (thanks to dl_yielded=1). |
aab03e05 | 1501 | */ |
48be3a67 PZ |
1502 | rq->curr->dl.dl_yielded = 1; |
1503 | ||
6f1607f1 | 1504 | update_rq_clock(rq); |
aab03e05 | 1505 | update_curr_dl(rq); |
44fb085b WL |
1506 | /* |
1507 | * Tell update_rq_clock() that we've just updated, | |
1508 | * so we don't do microscopic update in schedule() | |
1509 | * and double the fastpath cost. | |
1510 | */ | |
1511 | rq_clock_skip_update(rq, true); | |
aab03e05 DF |
1512 | } |
1513 | ||
1baca4ce JL |
1514 | #ifdef CONFIG_SMP |
1515 | ||
1516 | static int find_later_rq(struct task_struct *task); | |
1baca4ce JL |
1517 | |
1518 | static int | |
1519 | select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) | |
1520 | { | |
1521 | struct task_struct *curr; | |
1522 | struct rq *rq; | |
1523 | ||
1d7e974c | 1524 | if (sd_flag != SD_BALANCE_WAKE) |
1baca4ce JL |
1525 | goto out; |
1526 | ||
1527 | rq = cpu_rq(cpu); | |
1528 | ||
1529 | rcu_read_lock(); | |
316c1608 | 1530 | curr = READ_ONCE(rq->curr); /* unlocked access */ |
1baca4ce JL |
1531 | |
1532 | /* | |
1533 | * If we are dealing with a -deadline task, we must | |
1534 | * decide where to wake it up. | |
1535 | * If it has a later deadline and the current task | |
1536 | * on this rq can't move (provided the waking task | |
1537 | * can!) we prefer to send it somewhere else. On the | |
1538 | * other hand, if it has a shorter deadline, we | |
1539 | * try to make it stay here, it might be important. | |
1540 | */ | |
1541 | if (unlikely(dl_task(curr)) && | |
4b53a341 | 1542 | (curr->nr_cpus_allowed < 2 || |
1baca4ce | 1543 | !dl_entity_preempt(&p->dl, &curr->dl)) && |
4b53a341 | 1544 | (p->nr_cpus_allowed > 1)) { |
1baca4ce JL |
1545 | int target = find_later_rq(p); |
1546 | ||
9d514262 | 1547 | if (target != -1 && |
5aa50507 LA |
1548 | (dl_time_before(p->dl.deadline, |
1549 | cpu_rq(target)->dl.earliest_dl.curr) || | |
1550 | (cpu_rq(target)->dl.dl_nr_running == 0))) | |
1baca4ce JL |
1551 | cpu = target; |
1552 | } | |
1553 | rcu_read_unlock(); | |
1554 | ||
1555 | out: | |
1556 | return cpu; | |
1557 | } | |
1558 | ||
209a0cbd LA |
1559 | static void migrate_task_rq_dl(struct task_struct *p) |
1560 | { | |
1561 | struct rq *rq; | |
1562 | ||
8fd27231 | 1563 | if (p->state != TASK_WAKING) |
209a0cbd LA |
1564 | return; |
1565 | ||
1566 | rq = task_rq(p); | |
1567 | /* | |
1568 | * Since p->state == TASK_WAKING, set_task_cpu() has been called | |
1569 | * from try_to_wake_up(). Hence, p->pi_lock is locked, but | |
1570 | * rq->lock is not... So, lock it | |
1571 | */ | |
1572 | raw_spin_lock(&rq->lock); | |
8fd27231 LA |
1573 | if (p->dl.dl_non_contending) { |
1574 | sub_running_bw(p->dl.dl_bw, &rq->dl); | |
1575 | p->dl.dl_non_contending = 0; | |
1576 | /* | |
1577 | * If the timer handler is currently running and the | |
1578 | * timer cannot be cancelled, inactive_task_timer() | |
1579 | * will see that dl_not_contending is not set, and | |
1580 | * will not touch the rq's active utilization, | |
1581 | * so we are still safe. | |
1582 | */ | |
1583 | if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1) | |
1584 | put_task_struct(p); | |
1585 | } | |
1586 | sub_rq_bw(p->dl.dl_bw, &rq->dl); | |
209a0cbd LA |
1587 | raw_spin_unlock(&rq->lock); |
1588 | } | |
1589 | ||
1baca4ce JL |
1590 | static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p) |
1591 | { | |
1592 | /* | |
1593 | * Current can't be migrated, useless to reschedule, | |
1594 | * let's hope p can move out. | |
1595 | */ | |
4b53a341 | 1596 | if (rq->curr->nr_cpus_allowed == 1 || |
3261ed0b | 1597 | !cpudl_find(&rq->rd->cpudl, rq->curr, NULL)) |
1baca4ce JL |
1598 | return; |
1599 | ||
1600 | /* | |
1601 | * p is migratable, so let's not schedule it and | |
1602 | * see if it is pushed or pulled somewhere else. | |
1603 | */ | |
4b53a341 | 1604 | if (p->nr_cpus_allowed != 1 && |
3261ed0b | 1605 | cpudl_find(&rq->rd->cpudl, p, NULL)) |
1baca4ce JL |
1606 | return; |
1607 | ||
8875125e | 1608 | resched_curr(rq); |
1baca4ce JL |
1609 | } |
1610 | ||
1611 | #endif /* CONFIG_SMP */ | |
1612 | ||
aab03e05 DF |
1613 | /* |
1614 | * Only called when both the current and waking task are -deadline | |
1615 | * tasks. | |
1616 | */ | |
1617 | static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, | |
1618 | int flags) | |
1619 | { | |
1baca4ce | 1620 | if (dl_entity_preempt(&p->dl, &rq->curr->dl)) { |
8875125e | 1621 | resched_curr(rq); |
1baca4ce JL |
1622 | return; |
1623 | } | |
1624 | ||
1625 | #ifdef CONFIG_SMP | |
1626 | /* | |
1627 | * In the unlikely case current and p have the same deadline | |
1628 | * let us try to decide what's the best thing to do... | |
1629 | */ | |
332ac17e DF |
1630 | if ((p->dl.deadline == rq->curr->dl.deadline) && |
1631 | !test_tsk_need_resched(rq->curr)) | |
1baca4ce JL |
1632 | check_preempt_equal_dl(rq, p); |
1633 | #endif /* CONFIG_SMP */ | |
aab03e05 DF |
1634 | } |
1635 | ||
1636 | #ifdef CONFIG_SCHED_HRTICK | |
1637 | static void start_hrtick_dl(struct rq *rq, struct task_struct *p) | |
1638 | { | |
177ef2a6 | 1639 | hrtick_start(rq, p->dl.runtime); |
aab03e05 | 1640 | } |
36ce9881 WL |
1641 | #else /* !CONFIG_SCHED_HRTICK */ |
1642 | static void start_hrtick_dl(struct rq *rq, struct task_struct *p) | |
1643 | { | |
1644 | } | |
aab03e05 DF |
1645 | #endif |
1646 | ||
1647 | static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq, | |
1648 | struct dl_rq *dl_rq) | |
1649 | { | |
2161573e | 1650 | struct rb_node *left = rb_first_cached(&dl_rq->root); |
aab03e05 DF |
1651 | |
1652 | if (!left) | |
1653 | return NULL; | |
1654 | ||
1655 | return rb_entry(left, struct sched_dl_entity, rb_node); | |
1656 | } | |
1657 | ||
181a80d1 | 1658 | static struct task_struct * |
d8ac8971 | 1659 | pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) |
aab03e05 DF |
1660 | { |
1661 | struct sched_dl_entity *dl_se; | |
1662 | struct task_struct *p; | |
1663 | struct dl_rq *dl_rq; | |
1664 | ||
1665 | dl_rq = &rq->dl; | |
1666 | ||
a1d9a323 | 1667 | if (need_pull_dl_task(rq, prev)) { |
cbce1a68 PZ |
1668 | /* |
1669 | * This is OK, because current is on_cpu, which avoids it being | |
1670 | * picked for load-balance and preemption/IRQs are still | |
1671 | * disabled avoiding further scheduler activity on it and we're | |
1672 | * being very careful to re-start the picking loop. | |
1673 | */ | |
d8ac8971 | 1674 | rq_unpin_lock(rq, rf); |
38033c37 | 1675 | pull_dl_task(rq); |
d8ac8971 | 1676 | rq_repin_lock(rq, rf); |
a1d9a323 | 1677 | /* |
176cedc4 | 1678 | * pull_dl_task() can drop (and re-acquire) rq->lock; this |
a1d9a323 KT |
1679 | * means a stop task can slip in, in which case we need to |
1680 | * re-start task selection. | |
1681 | */ | |
da0c1e65 | 1682 | if (rq->stop && task_on_rq_queued(rq->stop)) |
a1d9a323 KT |
1683 | return RETRY_TASK; |
1684 | } | |
1685 | ||
734ff2a7 KT |
1686 | /* |
1687 | * When prev is DL, we may throttle it in put_prev_task(). | |
1688 | * So, we update time before we check for dl_nr_running. | |
1689 | */ | |
1690 | if (prev->sched_class == &dl_sched_class) | |
1691 | update_curr_dl(rq); | |
38033c37 | 1692 | |
aab03e05 DF |
1693 | if (unlikely(!dl_rq->dl_nr_running)) |
1694 | return NULL; | |
1695 | ||
3f1d2a31 | 1696 | put_prev_task(rq, prev); |
606dba2e | 1697 | |
aab03e05 DF |
1698 | dl_se = pick_next_dl_entity(rq, dl_rq); |
1699 | BUG_ON(!dl_se); | |
1700 | ||
1701 | p = dl_task_of(dl_se); | |
1702 | p->se.exec_start = rq_clock_task(rq); | |
1baca4ce JL |
1703 | |
1704 | /* Running task will never be pushed. */ | |
71362650 | 1705 | dequeue_pushable_dl_task(rq, p); |
1baca4ce | 1706 | |
aab03e05 DF |
1707 | if (hrtick_enabled(rq)) |
1708 | start_hrtick_dl(rq, p); | |
1baca4ce | 1709 | |
e3fca9e7 | 1710 | queue_push_tasks(rq); |
1baca4ce | 1711 | |
aab03e05 DF |
1712 | return p; |
1713 | } | |
1714 | ||
1715 | static void put_prev_task_dl(struct rq *rq, struct task_struct *p) | |
1716 | { | |
1717 | update_curr_dl(rq); | |
1baca4ce | 1718 | |
4b53a341 | 1719 | if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1) |
1baca4ce | 1720 | enqueue_pushable_dl_task(rq, p); |
aab03e05 DF |
1721 | } |
1722 | ||
1723 | static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued) | |
1724 | { | |
1725 | update_curr_dl(rq); | |
1726 | ||
a7bebf48 WL |
1727 | /* |
1728 | * Even when we have runtime, update_curr_dl() might have resulted in us | |
1729 | * not being the leftmost task anymore. In that case NEED_RESCHED will | |
1730 | * be set and schedule() will start a new hrtick for the next task. | |
1731 | */ | |
1732 | if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 && | |
1733 | is_leftmost(p, &rq->dl)) | |
aab03e05 | 1734 | start_hrtick_dl(rq, p); |
aab03e05 DF |
1735 | } |
1736 | ||
1737 | static void task_fork_dl(struct task_struct *p) | |
1738 | { | |
1739 | /* | |
1740 | * SCHED_DEADLINE tasks cannot fork and this is achieved through | |
1741 | * sched_fork() | |
1742 | */ | |
1743 | } | |
1744 | ||
aab03e05 DF |
1745 | static void set_curr_task_dl(struct rq *rq) |
1746 | { | |
1747 | struct task_struct *p = rq->curr; | |
1748 | ||
1749 | p->se.exec_start = rq_clock_task(rq); | |
1baca4ce JL |
1750 | |
1751 | /* You can't push away the running task */ | |
1752 | dequeue_pushable_dl_task(rq, p); | |
1753 | } | |
1754 | ||
1755 | #ifdef CONFIG_SMP | |
1756 | ||
1757 | /* Only try algorithms three times */ | |
1758 | #define DL_MAX_TRIES 3 | |
1759 | ||
1760 | static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu) | |
1761 | { | |
1762 | if (!task_running(rq, p) && | |
0c98d344 | 1763 | cpumask_test_cpu(cpu, &p->cpus_allowed)) |
1baca4ce | 1764 | return 1; |
1baca4ce JL |
1765 | return 0; |
1766 | } | |
1767 | ||
8b5e770e WL |
1768 | /* |
1769 | * Return the earliest pushable rq's task, which is suitable to be executed | |
1770 | * on the CPU, NULL otherwise: | |
1771 | */ | |
1772 | static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu) | |
1773 | { | |
2161573e | 1774 | struct rb_node *next_node = rq->dl.pushable_dl_tasks_root.rb_leftmost; |
8b5e770e WL |
1775 | struct task_struct *p = NULL; |
1776 | ||
1777 | if (!has_pushable_dl_tasks(rq)) | |
1778 | return NULL; | |
1779 | ||
1780 | next_node: | |
1781 | if (next_node) { | |
1782 | p = rb_entry(next_node, struct task_struct, pushable_dl_tasks); | |
1783 | ||
1784 | if (pick_dl_task(rq, p, cpu)) | |
1785 | return p; | |
1786 | ||
1787 | next_node = rb_next(next_node); | |
1788 | goto next_node; | |
1789 | } | |
1790 | ||
1791 | return NULL; | |
1792 | } | |
1793 | ||
1baca4ce JL |
1794 | static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl); |
1795 | ||
1796 | static int find_later_rq(struct task_struct *task) | |
1797 | { | |
1798 | struct sched_domain *sd; | |
4ba29684 | 1799 | struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl); |
1baca4ce | 1800 | int this_cpu = smp_processor_id(); |
b18c3ca1 | 1801 | int cpu = task_cpu(task); |
1baca4ce JL |
1802 | |
1803 | /* Make sure the mask is initialized first */ | |
1804 | if (unlikely(!later_mask)) | |
1805 | return -1; | |
1806 | ||
4b53a341 | 1807 | if (task->nr_cpus_allowed == 1) |
1baca4ce JL |
1808 | return -1; |
1809 | ||
91ec6778 JL |
1810 | /* |
1811 | * We have to consider system topology and task affinity | |
1812 | * first, then we can look for a suitable cpu. | |
1813 | */ | |
3261ed0b | 1814 | if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask)) |
1baca4ce JL |
1815 | return -1; |
1816 | ||
1817 | /* | |
b18c3ca1 BP |
1818 | * If we are here, some targets have been found, including |
1819 | * the most suitable which is, among the runqueues where the | |
1820 | * current tasks have later deadlines than the task's one, the | |
1821 | * rq with the latest possible one. | |
1baca4ce JL |
1822 | * |
1823 | * Now we check how well this matches with task's | |
1824 | * affinity and system topology. | |
1825 | * | |
1826 | * The last cpu where the task run is our first | |
1827 | * guess, since it is most likely cache-hot there. | |
1828 | */ | |
1829 | if (cpumask_test_cpu(cpu, later_mask)) | |
1830 | return cpu; | |
1831 | /* | |
1832 | * Check if this_cpu is to be skipped (i.e., it is | |
1833 | * not in the mask) or not. | |
1834 | */ | |
1835 | if (!cpumask_test_cpu(this_cpu, later_mask)) | |
1836 | this_cpu = -1; | |
1837 | ||
1838 | rcu_read_lock(); | |
1839 | for_each_domain(cpu, sd) { | |
1840 | if (sd->flags & SD_WAKE_AFFINE) { | |
b18c3ca1 | 1841 | int best_cpu; |
1baca4ce JL |
1842 | |
1843 | /* | |
1844 | * If possible, preempting this_cpu is | |
1845 | * cheaper than migrating. | |
1846 | */ | |
1847 | if (this_cpu != -1 && | |
1848 | cpumask_test_cpu(this_cpu, sched_domain_span(sd))) { | |
1849 | rcu_read_unlock(); | |
1850 | return this_cpu; | |
1851 | } | |
1852 | ||
b18c3ca1 BP |
1853 | best_cpu = cpumask_first_and(later_mask, |
1854 | sched_domain_span(sd)); | |
1baca4ce | 1855 | /* |
b18c3ca1 BP |
1856 | * Last chance: if a cpu being in both later_mask |
1857 | * and current sd span is valid, that becomes our | |
1858 | * choice. Of course, the latest possible cpu is | |
1859 | * already under consideration through later_mask. | |
1baca4ce | 1860 | */ |
b18c3ca1 | 1861 | if (best_cpu < nr_cpu_ids) { |
1baca4ce JL |
1862 | rcu_read_unlock(); |
1863 | return best_cpu; | |
1864 | } | |
1865 | } | |
1866 | } | |
1867 | rcu_read_unlock(); | |
1868 | ||
1869 | /* | |
1870 | * At this point, all our guesses failed, we just return | |
1871 | * 'something', and let the caller sort the things out. | |
1872 | */ | |
1873 | if (this_cpu != -1) | |
1874 | return this_cpu; | |
1875 | ||
1876 | cpu = cpumask_any(later_mask); | |
1877 | if (cpu < nr_cpu_ids) | |
1878 | return cpu; | |
1879 | ||
1880 | return -1; | |
1881 | } | |
1882 | ||
1883 | /* Locks the rq it finds */ | |
1884 | static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq) | |
1885 | { | |
1886 | struct rq *later_rq = NULL; | |
1887 | int tries; | |
1888 | int cpu; | |
1889 | ||
1890 | for (tries = 0; tries < DL_MAX_TRIES; tries++) { | |
1891 | cpu = find_later_rq(task); | |
1892 | ||
1893 | if ((cpu == -1) || (cpu == rq->cpu)) | |
1894 | break; | |
1895 | ||
1896 | later_rq = cpu_rq(cpu); | |
1897 | ||
5aa50507 LA |
1898 | if (later_rq->dl.dl_nr_running && |
1899 | !dl_time_before(task->dl.deadline, | |
9d514262 WL |
1900 | later_rq->dl.earliest_dl.curr)) { |
1901 | /* | |
1902 | * Target rq has tasks of equal or earlier deadline, | |
1903 | * retrying does not release any lock and is unlikely | |
1904 | * to yield a different result. | |
1905 | */ | |
1906 | later_rq = NULL; | |
1907 | break; | |
1908 | } | |
1909 | ||
1baca4ce JL |
1910 | /* Retry if something changed. */ |
1911 | if (double_lock_balance(rq, later_rq)) { | |
1912 | if (unlikely(task_rq(task) != rq || | |
0c98d344 | 1913 | !cpumask_test_cpu(later_rq->cpu, &task->cpus_allowed) || |
da0c1e65 | 1914 | task_running(rq, task) || |
13b5ab02 | 1915 | !dl_task(task) || |
da0c1e65 | 1916 | !task_on_rq_queued(task))) { |
1baca4ce JL |
1917 | double_unlock_balance(rq, later_rq); |
1918 | later_rq = NULL; | |
1919 | break; | |
1920 | } | |
1921 | } | |
1922 | ||
1923 | /* | |
1924 | * If the rq we found has no -deadline task, or | |
1925 | * its earliest one has a later deadline than our | |
1926 | * task, the rq is a good one. | |
1927 | */ | |
1928 | if (!later_rq->dl.dl_nr_running || | |
1929 | dl_time_before(task->dl.deadline, | |
1930 | later_rq->dl.earliest_dl.curr)) | |
1931 | break; | |
1932 | ||
1933 | /* Otherwise we try again. */ | |
1934 | double_unlock_balance(rq, later_rq); | |
1935 | later_rq = NULL; | |
1936 | } | |
1937 | ||
1938 | return later_rq; | |
1939 | } | |
1940 | ||
1941 | static struct task_struct *pick_next_pushable_dl_task(struct rq *rq) | |
1942 | { | |
1943 | struct task_struct *p; | |
1944 | ||
1945 | if (!has_pushable_dl_tasks(rq)) | |
1946 | return NULL; | |
1947 | ||
2161573e | 1948 | p = rb_entry(rq->dl.pushable_dl_tasks_root.rb_leftmost, |
1baca4ce JL |
1949 | struct task_struct, pushable_dl_tasks); |
1950 | ||
1951 | BUG_ON(rq->cpu != task_cpu(p)); | |
1952 | BUG_ON(task_current(rq, p)); | |
4b53a341 | 1953 | BUG_ON(p->nr_cpus_allowed <= 1); |
1baca4ce | 1954 | |
da0c1e65 | 1955 | BUG_ON(!task_on_rq_queued(p)); |
1baca4ce JL |
1956 | BUG_ON(!dl_task(p)); |
1957 | ||
1958 | return p; | |
1959 | } | |
1960 | ||
1961 | /* | |
1962 | * See if the non running -deadline tasks on this rq | |
1963 | * can be sent to some other CPU where they can preempt | |
1964 | * and start executing. | |
1965 | */ | |
1966 | static int push_dl_task(struct rq *rq) | |
1967 | { | |
1968 | struct task_struct *next_task; | |
1969 | struct rq *later_rq; | |
c51b8ab5 | 1970 | int ret = 0; |
1baca4ce JL |
1971 | |
1972 | if (!rq->dl.overloaded) | |
1973 | return 0; | |
1974 | ||
1975 | next_task = pick_next_pushable_dl_task(rq); | |
1976 | if (!next_task) | |
1977 | return 0; | |
1978 | ||
1979 | retry: | |
1980 | if (unlikely(next_task == rq->curr)) { | |
1981 | WARN_ON(1); | |
1982 | return 0; | |
1983 | } | |
1984 | ||
1985 | /* | |
1986 | * If next_task preempts rq->curr, and rq->curr | |
1987 | * can move away, it makes sense to just reschedule | |
1988 | * without going further in pushing next_task. | |
1989 | */ | |
1990 | if (dl_task(rq->curr) && | |
1991 | dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) && | |
4b53a341 | 1992 | rq->curr->nr_cpus_allowed > 1) { |
8875125e | 1993 | resched_curr(rq); |
1baca4ce JL |
1994 | return 0; |
1995 | } | |
1996 | ||
1997 | /* We might release rq lock */ | |
1998 | get_task_struct(next_task); | |
1999 | ||
2000 | /* Will lock the rq it'll find */ | |
2001 | later_rq = find_lock_later_rq(next_task, rq); | |
2002 | if (!later_rq) { | |
2003 | struct task_struct *task; | |
2004 | ||
2005 | /* | |
2006 | * We must check all this again, since | |
2007 | * find_lock_later_rq releases rq->lock and it is | |
2008 | * then possible that next_task has migrated. | |
2009 | */ | |
2010 | task = pick_next_pushable_dl_task(rq); | |
a776b968 | 2011 | if (task == next_task) { |
1baca4ce JL |
2012 | /* |
2013 | * The task is still there. We don't try | |
2014 | * again, some other cpu will pull it when ready. | |
2015 | */ | |
1baca4ce JL |
2016 | goto out; |
2017 | } | |
2018 | ||
2019 | if (!task) | |
2020 | /* No more tasks */ | |
2021 | goto out; | |
2022 | ||
2023 | put_task_struct(next_task); | |
2024 | next_task = task; | |
2025 | goto retry; | |
2026 | } | |
2027 | ||
2028 | deactivate_task(rq, next_task, 0); | |
e36d8677 | 2029 | sub_running_bw(next_task->dl.dl_bw, &rq->dl); |
8fd27231 | 2030 | sub_rq_bw(next_task->dl.dl_bw, &rq->dl); |
1baca4ce | 2031 | set_task_cpu(next_task, later_rq->cpu); |
8fd27231 | 2032 | add_rq_bw(next_task->dl.dl_bw, &later_rq->dl); |
e36d8677 | 2033 | add_running_bw(next_task->dl.dl_bw, &later_rq->dl); |
1baca4ce | 2034 | activate_task(later_rq, next_task, 0); |
c51b8ab5 | 2035 | ret = 1; |
1baca4ce | 2036 | |
8875125e | 2037 | resched_curr(later_rq); |
1baca4ce JL |
2038 | |
2039 | double_unlock_balance(rq, later_rq); | |
2040 | ||
2041 | out: | |
2042 | put_task_struct(next_task); | |
2043 | ||
c51b8ab5 | 2044 | return ret; |
1baca4ce JL |
2045 | } |
2046 | ||
2047 | static void push_dl_tasks(struct rq *rq) | |
2048 | { | |
4ffa08ed | 2049 | /* push_dl_task() will return true if it moved a -deadline task */ |
1baca4ce JL |
2050 | while (push_dl_task(rq)) |
2051 | ; | |
aab03e05 DF |
2052 | } |
2053 | ||
0ea60c20 | 2054 | static void pull_dl_task(struct rq *this_rq) |
1baca4ce | 2055 | { |
0ea60c20 | 2056 | int this_cpu = this_rq->cpu, cpu; |
1baca4ce | 2057 | struct task_struct *p; |
0ea60c20 | 2058 | bool resched = false; |
1baca4ce JL |
2059 | struct rq *src_rq; |
2060 | u64 dmin = LONG_MAX; | |
2061 | ||
2062 | if (likely(!dl_overloaded(this_rq))) | |
0ea60c20 | 2063 | return; |
1baca4ce JL |
2064 | |
2065 | /* | |
2066 | * Match the barrier from dl_set_overloaded; this guarantees that if we | |
2067 | * see overloaded we must also see the dlo_mask bit. | |
2068 | */ | |
2069 | smp_rmb(); | |
2070 | ||
2071 | for_each_cpu(cpu, this_rq->rd->dlo_mask) { | |
2072 | if (this_cpu == cpu) | |
2073 | continue; | |
2074 | ||
2075 | src_rq = cpu_rq(cpu); | |
2076 | ||
2077 | /* | |
2078 | * It looks racy, abd it is! However, as in sched_rt.c, | |
2079 | * we are fine with this. | |
2080 | */ | |
2081 | if (this_rq->dl.dl_nr_running && | |
2082 | dl_time_before(this_rq->dl.earliest_dl.curr, | |
2083 | src_rq->dl.earliest_dl.next)) | |
2084 | continue; | |
2085 | ||
2086 | /* Might drop this_rq->lock */ | |
2087 | double_lock_balance(this_rq, src_rq); | |
2088 | ||
2089 | /* | |
2090 | * If there are no more pullable tasks on the | |
2091 | * rq, we're done with it. | |
2092 | */ | |
2093 | if (src_rq->dl.dl_nr_running <= 1) | |
2094 | goto skip; | |
2095 | ||
8b5e770e | 2096 | p = pick_earliest_pushable_dl_task(src_rq, this_cpu); |
1baca4ce JL |
2097 | |
2098 | /* | |
2099 | * We found a task to be pulled if: | |
2100 | * - it preempts our current (if there's one), | |
2101 | * - it will preempt the last one we pulled (if any). | |
2102 | */ | |
2103 | if (p && dl_time_before(p->dl.deadline, dmin) && | |
2104 | (!this_rq->dl.dl_nr_running || | |
2105 | dl_time_before(p->dl.deadline, | |
2106 | this_rq->dl.earliest_dl.curr))) { | |
2107 | WARN_ON(p == src_rq->curr); | |
da0c1e65 | 2108 | WARN_ON(!task_on_rq_queued(p)); |
1baca4ce JL |
2109 | |
2110 | /* | |
2111 | * Then we pull iff p has actually an earlier | |
2112 | * deadline than the current task of its runqueue. | |
2113 | */ | |
2114 | if (dl_time_before(p->dl.deadline, | |
2115 | src_rq->curr->dl.deadline)) | |
2116 | goto skip; | |
2117 | ||
0ea60c20 | 2118 | resched = true; |
1baca4ce JL |
2119 | |
2120 | deactivate_task(src_rq, p, 0); | |
e36d8677 | 2121 | sub_running_bw(p->dl.dl_bw, &src_rq->dl); |
8fd27231 | 2122 | sub_rq_bw(p->dl.dl_bw, &src_rq->dl); |
1baca4ce | 2123 | set_task_cpu(p, this_cpu); |
8fd27231 | 2124 | add_rq_bw(p->dl.dl_bw, &this_rq->dl); |
e36d8677 | 2125 | add_running_bw(p->dl.dl_bw, &this_rq->dl); |
1baca4ce JL |
2126 | activate_task(this_rq, p, 0); |
2127 | dmin = p->dl.deadline; | |
2128 | ||
2129 | /* Is there any other task even earlier? */ | |
2130 | } | |
2131 | skip: | |
2132 | double_unlock_balance(this_rq, src_rq); | |
2133 | } | |
2134 | ||
0ea60c20 PZ |
2135 | if (resched) |
2136 | resched_curr(this_rq); | |
1baca4ce JL |
2137 | } |
2138 | ||
2139 | /* | |
2140 | * Since the task is not running and a reschedule is not going to happen | |
2141 | * anytime soon on its runqueue, we try pushing it away now. | |
2142 | */ | |
2143 | static void task_woken_dl(struct rq *rq, struct task_struct *p) | |
2144 | { | |
2145 | if (!task_running(rq, p) && | |
2146 | !test_tsk_need_resched(rq->curr) && | |
4b53a341 | 2147 | p->nr_cpus_allowed > 1 && |
1baca4ce | 2148 | dl_task(rq->curr) && |
4b53a341 | 2149 | (rq->curr->nr_cpus_allowed < 2 || |
6b0a563f | 2150 | !dl_entity_preempt(&p->dl, &rq->curr->dl))) { |
1baca4ce JL |
2151 | push_dl_tasks(rq); |
2152 | } | |
2153 | } | |
2154 | ||
2155 | static void set_cpus_allowed_dl(struct task_struct *p, | |
2156 | const struct cpumask *new_mask) | |
2157 | { | |
7f51412a | 2158 | struct root_domain *src_rd; |
6c37067e | 2159 | struct rq *rq; |
1baca4ce JL |
2160 | |
2161 | BUG_ON(!dl_task(p)); | |
2162 | ||
7f51412a JL |
2163 | rq = task_rq(p); |
2164 | src_rd = rq->rd; | |
2165 | /* | |
2166 | * Migrating a SCHED_DEADLINE task between exclusive | |
2167 | * cpusets (different root_domains) entails a bandwidth | |
2168 | * update. We already made space for us in the destination | |
2169 | * domain (see cpuset_can_attach()). | |
2170 | */ | |
2171 | if (!cpumask_intersects(src_rd->span, new_mask)) { | |
2172 | struct dl_bw *src_dl_b; | |
2173 | ||
2174 | src_dl_b = dl_bw_of(cpu_of(rq)); | |
2175 | /* | |
2176 | * We now free resources of the root_domain we are migrating | |
2177 | * off. In the worst case, sched_setattr() may temporary fail | |
2178 | * until we complete the update. | |
2179 | */ | |
2180 | raw_spin_lock(&src_dl_b->lock); | |
8c0944ce | 2181 | __dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p))); |
7f51412a JL |
2182 | raw_spin_unlock(&src_dl_b->lock); |
2183 | } | |
2184 | ||
6c37067e | 2185 | set_cpus_allowed_common(p, new_mask); |
1baca4ce JL |
2186 | } |
2187 | ||
2188 | /* Assumes rq->lock is held */ | |
2189 | static void rq_online_dl(struct rq *rq) | |
2190 | { | |
2191 | if (rq->dl.overloaded) | |
2192 | dl_set_overload(rq); | |
6bfd6d72 | 2193 | |
16b26943 | 2194 | cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu); |
6bfd6d72 | 2195 | if (rq->dl.dl_nr_running > 0) |
d8206bb3 | 2196 | cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr); |
1baca4ce JL |
2197 | } |
2198 | ||
2199 | /* Assumes rq->lock is held */ | |
2200 | static void rq_offline_dl(struct rq *rq) | |
2201 | { | |
2202 | if (rq->dl.overloaded) | |
2203 | dl_clear_overload(rq); | |
6bfd6d72 | 2204 | |
d8206bb3 | 2205 | cpudl_clear(&rq->rd->cpudl, rq->cpu); |
16b26943 | 2206 | cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu); |
1baca4ce JL |
2207 | } |
2208 | ||
a6c0e746 | 2209 | void __init init_sched_dl_class(void) |
1baca4ce JL |
2210 | { |
2211 | unsigned int i; | |
2212 | ||
2213 | for_each_possible_cpu(i) | |
2214 | zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i), | |
2215 | GFP_KERNEL, cpu_to_node(i)); | |
2216 | } | |
2217 | ||
2218 | #endif /* CONFIG_SMP */ | |
2219 | ||
aab03e05 DF |
2220 | static void switched_from_dl(struct rq *rq, struct task_struct *p) |
2221 | { | |
a649f237 | 2222 | /* |
209a0cbd LA |
2223 | * task_non_contending() can start the "inactive timer" (if the 0-lag |
2224 | * time is in the future). If the task switches back to dl before | |
2225 | * the "inactive timer" fires, it can continue to consume its current | |
2226 | * runtime using its current deadline. If it stays outside of | |
2227 | * SCHED_DEADLINE until the 0-lag time passes, inactive_task_timer() | |
2228 | * will reset the task parameters. | |
a649f237 | 2229 | */ |
209a0cbd LA |
2230 | if (task_on_rq_queued(p) && p->dl.dl_runtime) |
2231 | task_non_contending(p); | |
2232 | ||
8fd27231 LA |
2233 | if (!task_on_rq_queued(p)) |
2234 | sub_rq_bw(p->dl.dl_bw, &rq->dl); | |
2235 | ||
209a0cbd LA |
2236 | /* |
2237 | * We cannot use inactive_task_timer() to invoke sub_running_bw() | |
2238 | * at the 0-lag time, because the task could have been migrated | |
2239 | * while SCHED_OTHER in the meanwhile. | |
2240 | */ | |
2241 | if (p->dl.dl_non_contending) | |
2242 | p->dl.dl_non_contending = 0; | |
a5e7be3b | 2243 | |
1baca4ce JL |
2244 | /* |
2245 | * Since this might be the only -deadline task on the rq, | |
2246 | * this is the right place to try to pull some other one | |
2247 | * from an overloaded cpu, if any. | |
2248 | */ | |
cd660911 WL |
2249 | if (!task_on_rq_queued(p) || rq->dl.dl_nr_running) |
2250 | return; | |
2251 | ||
9916e214 | 2252 | queue_pull_task(rq); |
aab03e05 DF |
2253 | } |
2254 | ||
1baca4ce JL |
2255 | /* |
2256 | * When switching to -deadline, we may overload the rq, then | |
2257 | * we try to push someone off, if possible. | |
2258 | */ | |
aab03e05 DF |
2259 | static void switched_to_dl(struct rq *rq, struct task_struct *p) |
2260 | { | |
209a0cbd LA |
2261 | if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1) |
2262 | put_task_struct(p); | |
98b0a857 JL |
2263 | |
2264 | /* If p is not queued we will update its parameters at next wakeup. */ | |
8fd27231 LA |
2265 | if (!task_on_rq_queued(p)) { |
2266 | add_rq_bw(p->dl.dl_bw, &rq->dl); | |
98b0a857 | 2267 | |
8fd27231 LA |
2268 | return; |
2269 | } | |
72f9f3fd | 2270 | |
98b0a857 | 2271 | if (rq->curr != p) { |
1baca4ce | 2272 | #ifdef CONFIG_SMP |
4b53a341 | 2273 | if (p->nr_cpus_allowed > 1 && rq->dl.overloaded) |
9916e214 | 2274 | queue_push_tasks(rq); |
619bd4a7 | 2275 | #endif |
9916e214 PZ |
2276 | if (dl_task(rq->curr)) |
2277 | check_preempt_curr_dl(rq, p, 0); | |
2278 | else | |
2279 | resched_curr(rq); | |
aab03e05 DF |
2280 | } |
2281 | } | |
2282 | ||
1baca4ce JL |
2283 | /* |
2284 | * If the scheduling parameters of a -deadline task changed, | |
2285 | * a push or pull operation might be needed. | |
2286 | */ | |
aab03e05 DF |
2287 | static void prio_changed_dl(struct rq *rq, struct task_struct *p, |
2288 | int oldprio) | |
2289 | { | |
da0c1e65 | 2290 | if (task_on_rq_queued(p) || rq->curr == p) { |
aab03e05 | 2291 | #ifdef CONFIG_SMP |
1baca4ce JL |
2292 | /* |
2293 | * This might be too much, but unfortunately | |
2294 | * we don't have the old deadline value, and | |
2295 | * we can't argue if the task is increasing | |
2296 | * or lowering its prio, so... | |
2297 | */ | |
2298 | if (!rq->dl.overloaded) | |
9916e214 | 2299 | queue_pull_task(rq); |
1baca4ce JL |
2300 | |
2301 | /* | |
2302 | * If we now have a earlier deadline task than p, | |
2303 | * then reschedule, provided p is still on this | |
2304 | * runqueue. | |
2305 | */ | |
9916e214 | 2306 | if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline)) |
8875125e | 2307 | resched_curr(rq); |
1baca4ce JL |
2308 | #else |
2309 | /* | |
2310 | * Again, we don't know if p has a earlier | |
2311 | * or later deadline, so let's blindly set a | |
2312 | * (maybe not needed) rescheduling point. | |
2313 | */ | |
8875125e | 2314 | resched_curr(rq); |
1baca4ce | 2315 | #endif /* CONFIG_SMP */ |
801ccdbf | 2316 | } |
aab03e05 | 2317 | } |
aab03e05 DF |
2318 | |
2319 | const struct sched_class dl_sched_class = { | |
2320 | .next = &rt_sched_class, | |
2321 | .enqueue_task = enqueue_task_dl, | |
2322 | .dequeue_task = dequeue_task_dl, | |
2323 | .yield_task = yield_task_dl, | |
2324 | ||
2325 | .check_preempt_curr = check_preempt_curr_dl, | |
2326 | ||
2327 | .pick_next_task = pick_next_task_dl, | |
2328 | .put_prev_task = put_prev_task_dl, | |
2329 | ||
2330 | #ifdef CONFIG_SMP | |
2331 | .select_task_rq = select_task_rq_dl, | |
209a0cbd | 2332 | .migrate_task_rq = migrate_task_rq_dl, |
1baca4ce JL |
2333 | .set_cpus_allowed = set_cpus_allowed_dl, |
2334 | .rq_online = rq_online_dl, | |
2335 | .rq_offline = rq_offline_dl, | |
1baca4ce | 2336 | .task_woken = task_woken_dl, |
aab03e05 DF |
2337 | #endif |
2338 | ||
2339 | .set_curr_task = set_curr_task_dl, | |
2340 | .task_tick = task_tick_dl, | |
2341 | .task_fork = task_fork_dl, | |
aab03e05 DF |
2342 | |
2343 | .prio_changed = prio_changed_dl, | |
2344 | .switched_from = switched_from_dl, | |
2345 | .switched_to = switched_to_dl, | |
6e998916 SG |
2346 | |
2347 | .update_curr = update_curr_dl, | |
aab03e05 | 2348 | }; |
acb32132 | 2349 | |
06a76fe0 NP |
2350 | int sched_dl_global_validate(void) |
2351 | { | |
2352 | u64 runtime = global_rt_runtime(); | |
2353 | u64 period = global_rt_period(); | |
2354 | u64 new_bw = to_ratio(period, runtime); | |
2355 | struct dl_bw *dl_b; | |
2356 | int cpu, ret = 0; | |
2357 | unsigned long flags; | |
2358 | ||
2359 | /* | |
2360 | * Here we want to check the bandwidth not being set to some | |
2361 | * value smaller than the currently allocated bandwidth in | |
2362 | * any of the root_domains. | |
2363 | * | |
2364 | * FIXME: Cycling on all the CPUs is overdoing, but simpler than | |
2365 | * cycling on root_domains... Discussion on different/better | |
2366 | * solutions is welcome! | |
2367 | */ | |
2368 | for_each_possible_cpu(cpu) { | |
2369 | rcu_read_lock_sched(); | |
2370 | dl_b = dl_bw_of(cpu); | |
2371 | ||
2372 | raw_spin_lock_irqsave(&dl_b->lock, flags); | |
2373 | if (new_bw < dl_b->total_bw) | |
2374 | ret = -EBUSY; | |
2375 | raw_spin_unlock_irqrestore(&dl_b->lock, flags); | |
2376 | ||
2377 | rcu_read_unlock_sched(); | |
2378 | ||
2379 | if (ret) | |
2380 | break; | |
2381 | } | |
2382 | ||
2383 | return ret; | |
2384 | } | |
2385 | ||
2386 | void init_dl_rq_bw_ratio(struct dl_rq *dl_rq) | |
2387 | { | |
2388 | if (global_rt_runtime() == RUNTIME_INF) { | |
2389 | dl_rq->bw_ratio = 1 << RATIO_SHIFT; | |
2390 | dl_rq->extra_bw = 1 << BW_SHIFT; | |
2391 | } else { | |
2392 | dl_rq->bw_ratio = to_ratio(global_rt_runtime(), | |
2393 | global_rt_period()) >> (BW_SHIFT - RATIO_SHIFT); | |
2394 | dl_rq->extra_bw = to_ratio(global_rt_period(), | |
2395 | global_rt_runtime()); | |
2396 | } | |
2397 | } | |
2398 | ||
2399 | void sched_dl_do_global(void) | |
2400 | { | |
2401 | u64 new_bw = -1; | |
2402 | struct dl_bw *dl_b; | |
2403 | int cpu; | |
2404 | unsigned long flags; | |
2405 | ||
2406 | def_dl_bandwidth.dl_period = global_rt_period(); | |
2407 | def_dl_bandwidth.dl_runtime = global_rt_runtime(); | |
2408 | ||
2409 | if (global_rt_runtime() != RUNTIME_INF) | |
2410 | new_bw = to_ratio(global_rt_period(), global_rt_runtime()); | |
2411 | ||
2412 | /* | |
2413 | * FIXME: As above... | |
2414 | */ | |
2415 | for_each_possible_cpu(cpu) { | |
2416 | rcu_read_lock_sched(); | |
2417 | dl_b = dl_bw_of(cpu); | |
2418 | ||
2419 | raw_spin_lock_irqsave(&dl_b->lock, flags); | |
2420 | dl_b->bw = new_bw; | |
2421 | raw_spin_unlock_irqrestore(&dl_b->lock, flags); | |
2422 | ||
2423 | rcu_read_unlock_sched(); | |
2424 | init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl); | |
2425 | } | |
2426 | } | |
2427 | ||
2428 | /* | |
2429 | * We must be sure that accepting a new task (or allowing changing the | |
2430 | * parameters of an existing one) is consistent with the bandwidth | |
2431 | * constraints. If yes, this function also accordingly updates the currently | |
2432 | * allocated bandwidth to reflect the new situation. | |
2433 | * | |
2434 | * This function is called while holding p's rq->lock. | |
2435 | */ | |
2436 | int sched_dl_overflow(struct task_struct *p, int policy, | |
2437 | const struct sched_attr *attr) | |
2438 | { | |
2439 | struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); | |
2440 | u64 period = attr->sched_period ?: attr->sched_deadline; | |
2441 | u64 runtime = attr->sched_runtime; | |
2442 | u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0; | |
2443 | int cpus, err = -1; | |
2444 | ||
2445 | /* !deadline task may carry old deadline bandwidth */ | |
2446 | if (new_bw == p->dl.dl_bw && task_has_dl_policy(p)) | |
2447 | return 0; | |
2448 | ||
2449 | /* | |
2450 | * Either if a task, enters, leave, or stays -deadline but changes | |
2451 | * its parameters, we may need to update accordingly the total | |
2452 | * allocated bandwidth of the container. | |
2453 | */ | |
2454 | raw_spin_lock(&dl_b->lock); | |
2455 | cpus = dl_bw_cpus(task_cpu(p)); | |
2456 | if (dl_policy(policy) && !task_has_dl_policy(p) && | |
2457 | !__dl_overflow(dl_b, cpus, 0, new_bw)) { | |
2458 | if (hrtimer_active(&p->dl.inactive_timer)) | |
8c0944ce | 2459 | __dl_sub(dl_b, p->dl.dl_bw, cpus); |
06a76fe0 NP |
2460 | __dl_add(dl_b, new_bw, cpus); |
2461 | err = 0; | |
2462 | } else if (dl_policy(policy) && task_has_dl_policy(p) && | |
2463 | !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) { | |
2464 | /* | |
2465 | * XXX this is slightly incorrect: when the task | |
2466 | * utilization decreases, we should delay the total | |
2467 | * utilization change until the task's 0-lag point. | |
2468 | * But this would require to set the task's "inactive | |
2469 | * timer" when the task is not inactive. | |
2470 | */ | |
8c0944ce | 2471 | __dl_sub(dl_b, p->dl.dl_bw, cpus); |
06a76fe0 NP |
2472 | __dl_add(dl_b, new_bw, cpus); |
2473 | dl_change_utilization(p, new_bw); | |
2474 | err = 0; | |
2475 | } else if (!dl_policy(policy) && task_has_dl_policy(p)) { | |
2476 | /* | |
2477 | * Do not decrease the total deadline utilization here, | |
2478 | * switched_from_dl() will take care to do it at the correct | |
2479 | * (0-lag) time. | |
2480 | */ | |
2481 | err = 0; | |
2482 | } | |
2483 | raw_spin_unlock(&dl_b->lock); | |
2484 | ||
2485 | return err; | |
2486 | } | |
2487 | ||
2488 | /* | |
2489 | * This function initializes the sched_dl_entity of a newly becoming | |
2490 | * SCHED_DEADLINE task. | |
2491 | * | |
2492 | * Only the static values are considered here, the actual runtime and the | |
2493 | * absolute deadline will be properly calculated when the task is enqueued | |
2494 | * for the first time with its new policy. | |
2495 | */ | |
2496 | void __setparam_dl(struct task_struct *p, const struct sched_attr *attr) | |
2497 | { | |
2498 | struct sched_dl_entity *dl_se = &p->dl; | |
2499 | ||
2500 | dl_se->dl_runtime = attr->sched_runtime; | |
2501 | dl_se->dl_deadline = attr->sched_deadline; | |
2502 | dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline; | |
2503 | dl_se->flags = attr->sched_flags; | |
2504 | dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime); | |
2505 | dl_se->dl_density = to_ratio(dl_se->dl_deadline, dl_se->dl_runtime); | |
2506 | } | |
2507 | ||
2508 | void __getparam_dl(struct task_struct *p, struct sched_attr *attr) | |
2509 | { | |
2510 | struct sched_dl_entity *dl_se = &p->dl; | |
2511 | ||
2512 | attr->sched_priority = p->rt_priority; | |
2513 | attr->sched_runtime = dl_se->dl_runtime; | |
2514 | attr->sched_deadline = dl_se->dl_deadline; | |
2515 | attr->sched_period = dl_se->dl_period; | |
2516 | attr->sched_flags = dl_se->flags; | |
2517 | } | |
2518 | ||
2519 | /* | |
2520 | * This function validates the new parameters of a -deadline task. | |
2521 | * We ask for the deadline not being zero, and greater or equal | |
2522 | * than the runtime, as well as the period of being zero or | |
2523 | * greater than deadline. Furthermore, we have to be sure that | |
2524 | * user parameters are above the internal resolution of 1us (we | |
2525 | * check sched_runtime only since it is always the smaller one) and | |
2526 | * below 2^63 ns (we have to check both sched_deadline and | |
2527 | * sched_period, as the latter can be zero). | |
2528 | */ | |
2529 | bool __checkparam_dl(const struct sched_attr *attr) | |
2530 | { | |
2531 | /* deadline != 0 */ | |
2532 | if (attr->sched_deadline == 0) | |
2533 | return false; | |
2534 | ||
2535 | /* | |
2536 | * Since we truncate DL_SCALE bits, make sure we're at least | |
2537 | * that big. | |
2538 | */ | |
2539 | if (attr->sched_runtime < (1ULL << DL_SCALE)) | |
2540 | return false; | |
2541 | ||
2542 | /* | |
2543 | * Since we use the MSB for wrap-around and sign issues, make | |
2544 | * sure it's not set (mind that period can be equal to zero). | |
2545 | */ | |
2546 | if (attr->sched_deadline & (1ULL << 63) || | |
2547 | attr->sched_period & (1ULL << 63)) | |
2548 | return false; | |
2549 | ||
2550 | /* runtime <= deadline <= period (if period != 0) */ | |
2551 | if ((attr->sched_period != 0 && | |
2552 | attr->sched_period < attr->sched_deadline) || | |
2553 | attr->sched_deadline < attr->sched_runtime) | |
2554 | return false; | |
2555 | ||
2556 | return true; | |
2557 | } | |
2558 | ||
2559 | /* | |
2560 | * This function clears the sched_dl_entity static params. | |
2561 | */ | |
2562 | void __dl_clear_params(struct task_struct *p) | |
2563 | { | |
2564 | struct sched_dl_entity *dl_se = &p->dl; | |
2565 | ||
2566 | dl_se->dl_runtime = 0; | |
2567 | dl_se->dl_deadline = 0; | |
2568 | dl_se->dl_period = 0; | |
2569 | dl_se->flags = 0; | |
2570 | dl_se->dl_bw = 0; | |
2571 | dl_se->dl_density = 0; | |
2572 | ||
2573 | dl_se->dl_throttled = 0; | |
2574 | dl_se->dl_yielded = 0; | |
2575 | dl_se->dl_non_contending = 0; | |
34be3930 | 2576 | dl_se->dl_overrun = 0; |
06a76fe0 NP |
2577 | } |
2578 | ||
2579 | bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr) | |
2580 | { | |
2581 | struct sched_dl_entity *dl_se = &p->dl; | |
2582 | ||
2583 | if (dl_se->dl_runtime != attr->sched_runtime || | |
2584 | dl_se->dl_deadline != attr->sched_deadline || | |
2585 | dl_se->dl_period != attr->sched_period || | |
2586 | dl_se->flags != attr->sched_flags) | |
2587 | return true; | |
2588 | ||
2589 | return false; | |
2590 | } | |
2591 | ||
2592 | #ifdef CONFIG_SMP | |
2593 | int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed) | |
2594 | { | |
2595 | unsigned int dest_cpu = cpumask_any_and(cpu_active_mask, | |
2596 | cs_cpus_allowed); | |
2597 | struct dl_bw *dl_b; | |
2598 | bool overflow; | |
2599 | int cpus, ret; | |
2600 | unsigned long flags; | |
2601 | ||
2602 | rcu_read_lock_sched(); | |
2603 | dl_b = dl_bw_of(dest_cpu); | |
2604 | raw_spin_lock_irqsave(&dl_b->lock, flags); | |
2605 | cpus = dl_bw_cpus(dest_cpu); | |
2606 | overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw); | |
2607 | if (overflow) | |
2608 | ret = -EBUSY; | |
2609 | else { | |
2610 | /* | |
2611 | * We reserve space for this task in the destination | |
2612 | * root_domain, as we can't fail after this point. | |
2613 | * We will free resources in the source root_domain | |
2614 | * later on (see set_cpus_allowed_dl()). | |
2615 | */ | |
2616 | __dl_add(dl_b, p->dl.dl_bw, cpus); | |
2617 | ret = 0; | |
2618 | } | |
2619 | raw_spin_unlock_irqrestore(&dl_b->lock, flags); | |
2620 | rcu_read_unlock_sched(); | |
2621 | return ret; | |
2622 | } | |
2623 | ||
2624 | int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur, | |
2625 | const struct cpumask *trial) | |
2626 | { | |
2627 | int ret = 1, trial_cpus; | |
2628 | struct dl_bw *cur_dl_b; | |
2629 | unsigned long flags; | |
2630 | ||
2631 | rcu_read_lock_sched(); | |
2632 | cur_dl_b = dl_bw_of(cpumask_any(cur)); | |
2633 | trial_cpus = cpumask_weight(trial); | |
2634 | ||
2635 | raw_spin_lock_irqsave(&cur_dl_b->lock, flags); | |
2636 | if (cur_dl_b->bw != -1 && | |
2637 | cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw) | |
2638 | ret = 0; | |
2639 | raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags); | |
2640 | rcu_read_unlock_sched(); | |
2641 | return ret; | |
2642 | } | |
2643 | ||
2644 | bool dl_cpu_busy(unsigned int cpu) | |
2645 | { | |
2646 | unsigned long flags; | |
2647 | struct dl_bw *dl_b; | |
2648 | bool overflow; | |
2649 | int cpus; | |
2650 | ||
2651 | rcu_read_lock_sched(); | |
2652 | dl_b = dl_bw_of(cpu); | |
2653 | raw_spin_lock_irqsave(&dl_b->lock, flags); | |
2654 | cpus = dl_bw_cpus(cpu); | |
2655 | overflow = __dl_overflow(dl_b, cpus, 0, 0); | |
2656 | raw_spin_unlock_irqrestore(&dl_b->lock, flags); | |
2657 | rcu_read_unlock_sched(); | |
2658 | return overflow; | |
2659 | } | |
2660 | #endif | |
2661 | ||
acb32132 WL |
2662 | #ifdef CONFIG_SCHED_DEBUG |
2663 | extern void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq); | |
2664 | ||
2665 | void print_dl_stats(struct seq_file *m, int cpu) | |
2666 | { | |
2667 | print_dl_rq(m, cpu, &cpu_rq(cpu)->dl); | |
2668 | } | |
2669 | #endif /* CONFIG_SCHED_DEBUG */ |