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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" | |
3727e0e1 | 19 | #include "pelt.h" |
aab03e05 | 20 | |
332ac17e DF |
21 | struct dl_bandwidth def_dl_bandwidth; |
22 | ||
aab03e05 DF |
23 | static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se) |
24 | { | |
25 | return container_of(dl_se, struct task_struct, dl); | |
26 | } | |
27 | ||
28 | static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq) | |
29 | { | |
30 | return container_of(dl_rq, struct rq, dl); | |
31 | } | |
32 | ||
33 | static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se) | |
34 | { | |
35 | struct task_struct *p = dl_task_of(dl_se); | |
36 | struct rq *rq = task_rq(p); | |
37 | ||
38 | return &rq->dl; | |
39 | } | |
40 | ||
41 | static inline int on_dl_rq(struct sched_dl_entity *dl_se) | |
42 | { | |
43 | return !RB_EMPTY_NODE(&dl_se->rb_node); | |
44 | } | |
45 | ||
06a76fe0 NP |
46 | #ifdef CONFIG_SMP |
47 | static inline struct dl_bw *dl_bw_of(int i) | |
48 | { | |
49 | RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), | |
50 | "sched RCU must be held"); | |
51 | return &cpu_rq(i)->rd->dl_bw; | |
52 | } | |
53 | ||
54 | static inline int dl_bw_cpus(int i) | |
55 | { | |
56 | struct root_domain *rd = cpu_rq(i)->rd; | |
c81b8932 | 57 | int cpus; |
06a76fe0 NP |
58 | |
59 | RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), | |
60 | "sched RCU must be held"); | |
c81b8932 DE |
61 | |
62 | if (cpumask_subset(rd->span, cpu_active_mask)) | |
63 | return cpumask_weight(rd->span); | |
64 | ||
65 | cpus = 0; | |
66 | ||
06a76fe0 NP |
67 | for_each_cpu_and(i, rd->span, cpu_active_mask) |
68 | cpus++; | |
69 | ||
70 | return cpus; | |
71 | } | |
fc9dc698 DE |
72 | |
73 | static inline unsigned long __dl_bw_capacity(int i) | |
74 | { | |
75 | struct root_domain *rd = cpu_rq(i)->rd; | |
76 | unsigned long cap = 0; | |
77 | ||
78 | RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), | |
79 | "sched RCU must be held"); | |
80 | ||
81 | for_each_cpu_and(i, rd->span, cpu_active_mask) | |
82 | cap += capacity_orig_of(i); | |
83 | ||
84 | return cap; | |
85 | } | |
86 | ||
87 | /* | |
88 | * XXX Fix: If 'rq->rd == def_root_domain' perform AC against capacity | |
89 | * of the CPU the task is running on rather rd's \Sum CPU capacity. | |
90 | */ | |
91 | static inline unsigned long dl_bw_capacity(int i) | |
92 | { | |
93 | if (!static_branch_unlikely(&sched_asym_cpucapacity) && | |
94 | capacity_orig_of(i) == SCHED_CAPACITY_SCALE) { | |
95 | return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT; | |
96 | } else { | |
97 | return __dl_bw_capacity(i); | |
98 | } | |
99 | } | |
26762423 PL |
100 | |
101 | static inline bool dl_bw_visited(int cpu, u64 gen) | |
102 | { | |
103 | struct root_domain *rd = cpu_rq(cpu)->rd; | |
104 | ||
105 | if (rd->visit_gen == gen) | |
106 | return true; | |
107 | ||
108 | rd->visit_gen = gen; | |
109 | return false; | |
110 | } | |
06a76fe0 NP |
111 | #else |
112 | static inline struct dl_bw *dl_bw_of(int i) | |
113 | { | |
114 | return &cpu_rq(i)->dl.dl_bw; | |
115 | } | |
116 | ||
117 | static inline int dl_bw_cpus(int i) | |
118 | { | |
119 | return 1; | |
120 | } | |
fc9dc698 DE |
121 | |
122 | static inline unsigned long dl_bw_capacity(int i) | |
123 | { | |
124 | return SCHED_CAPACITY_SCALE; | |
125 | } | |
26762423 PL |
126 | |
127 | static inline bool dl_bw_visited(int cpu, u64 gen) | |
128 | { | |
129 | return false; | |
130 | } | |
06a76fe0 NP |
131 | #endif |
132 | ||
e36d8677 | 133 | static inline |
794a56eb | 134 | void __add_running_bw(u64 dl_bw, struct dl_rq *dl_rq) |
e36d8677 LA |
135 | { |
136 | u64 old = dl_rq->running_bw; | |
137 | ||
138 | lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); | |
139 | dl_rq->running_bw += dl_bw; | |
140 | SCHED_WARN_ON(dl_rq->running_bw < old); /* overflow */ | |
8fd27231 | 141 | SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw); |
e0367b12 | 142 | /* kick cpufreq (see the comment in kernel/sched/sched.h). */ |
4042d003 | 143 | cpufreq_update_util(rq_of_dl_rq(dl_rq), 0); |
e36d8677 LA |
144 | } |
145 | ||
146 | static inline | |
794a56eb | 147 | void __sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq) |
e36d8677 LA |
148 | { |
149 | u64 old = dl_rq->running_bw; | |
150 | ||
151 | lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); | |
152 | dl_rq->running_bw -= dl_bw; | |
153 | SCHED_WARN_ON(dl_rq->running_bw > old); /* underflow */ | |
154 | if (dl_rq->running_bw > old) | |
155 | dl_rq->running_bw = 0; | |
e0367b12 | 156 | /* kick cpufreq (see the comment in kernel/sched/sched.h). */ |
4042d003 | 157 | cpufreq_update_util(rq_of_dl_rq(dl_rq), 0); |
e36d8677 LA |
158 | } |
159 | ||
8fd27231 | 160 | static inline |
794a56eb | 161 | void __add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq) |
8fd27231 LA |
162 | { |
163 | u64 old = dl_rq->this_bw; | |
164 | ||
165 | lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); | |
166 | dl_rq->this_bw += dl_bw; | |
167 | SCHED_WARN_ON(dl_rq->this_bw < old); /* overflow */ | |
168 | } | |
169 | ||
170 | static inline | |
794a56eb | 171 | void __sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq) |
8fd27231 LA |
172 | { |
173 | u64 old = dl_rq->this_bw; | |
174 | ||
175 | lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); | |
176 | dl_rq->this_bw -= dl_bw; | |
177 | SCHED_WARN_ON(dl_rq->this_bw > old); /* underflow */ | |
178 | if (dl_rq->this_bw > old) | |
179 | dl_rq->this_bw = 0; | |
180 | SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw); | |
181 | } | |
182 | ||
794a56eb JL |
183 | static inline |
184 | void add_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
185 | { | |
186 | if (!dl_entity_is_special(dl_se)) | |
187 | __add_rq_bw(dl_se->dl_bw, dl_rq); | |
188 | } | |
189 | ||
190 | static inline | |
191 | void sub_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
192 | { | |
193 | if (!dl_entity_is_special(dl_se)) | |
194 | __sub_rq_bw(dl_se->dl_bw, dl_rq); | |
195 | } | |
196 | ||
197 | static inline | |
198 | void add_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
199 | { | |
200 | if (!dl_entity_is_special(dl_se)) | |
201 | __add_running_bw(dl_se->dl_bw, dl_rq); | |
202 | } | |
203 | ||
204 | static inline | |
205 | void sub_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
206 | { | |
207 | if (!dl_entity_is_special(dl_se)) | |
208 | __sub_running_bw(dl_se->dl_bw, dl_rq); | |
209 | } | |
210 | ||
ba4f7bc1 | 211 | static void dl_change_utilization(struct task_struct *p, u64 new_bw) |
209a0cbd | 212 | { |
8fd27231 | 213 | struct rq *rq; |
209a0cbd | 214 | |
794a56eb JL |
215 | BUG_ON(p->dl.flags & SCHED_FLAG_SUGOV); |
216 | ||
8fd27231 | 217 | if (task_on_rq_queued(p)) |
209a0cbd LA |
218 | return; |
219 | ||
8fd27231 LA |
220 | rq = task_rq(p); |
221 | if (p->dl.dl_non_contending) { | |
794a56eb | 222 | sub_running_bw(&p->dl, &rq->dl); |
8fd27231 LA |
223 | p->dl.dl_non_contending = 0; |
224 | /* | |
225 | * If the timer handler is currently running and the | |
226 | * timer cannot be cancelled, inactive_task_timer() | |
227 | * will see that dl_not_contending is not set, and | |
228 | * will not touch the rq's active utilization, | |
229 | * so we are still safe. | |
230 | */ | |
231 | if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1) | |
232 | put_task_struct(p); | |
233 | } | |
794a56eb JL |
234 | __sub_rq_bw(p->dl.dl_bw, &rq->dl); |
235 | __add_rq_bw(new_bw, &rq->dl); | |
209a0cbd LA |
236 | } |
237 | ||
238 | /* | |
239 | * The utilization of a task cannot be immediately removed from | |
240 | * the rq active utilization (running_bw) when the task blocks. | |
241 | * Instead, we have to wait for the so called "0-lag time". | |
242 | * | |
243 | * If a task blocks before the "0-lag time", a timer (the inactive | |
244 | * timer) is armed, and running_bw is decreased when the timer | |
245 | * fires. | |
246 | * | |
247 | * If the task wakes up again before the inactive timer fires, | |
248 | * the timer is cancelled, whereas if the task wakes up after the | |
249 | * inactive timer fired (and running_bw has been decreased) the | |
250 | * task's utilization has to be added to running_bw again. | |
251 | * A flag in the deadline scheduling entity (dl_non_contending) | |
252 | * is used to avoid race conditions between the inactive timer handler | |
253 | * and task wakeups. | |
254 | * | |
255 | * The following diagram shows how running_bw is updated. A task is | |
256 | * "ACTIVE" when its utilization contributes to running_bw; an | |
257 | * "ACTIVE contending" task is in the TASK_RUNNING state, while an | |
258 | * "ACTIVE non contending" task is a blocked task for which the "0-lag time" | |
259 | * has not passed yet. An "INACTIVE" task is a task for which the "0-lag" | |
260 | * time already passed, which does not contribute to running_bw anymore. | |
261 | * +------------------+ | |
262 | * wakeup | ACTIVE | | |
263 | * +------------------>+ contending | | |
264 | * | add_running_bw | | | |
265 | * | +----+------+------+ | |
266 | * | | ^ | |
267 | * | dequeue | | | |
268 | * +--------+-------+ | | | |
269 | * | | t >= 0-lag | | wakeup | |
270 | * | INACTIVE |<---------------+ | | |
271 | * | | sub_running_bw | | | |
272 | * +--------+-------+ | | | |
273 | * ^ | | | |
274 | * | t < 0-lag | | | |
275 | * | | | | |
276 | * | V | | |
277 | * | +----+------+------+ | |
278 | * | sub_running_bw | ACTIVE | | |
279 | * +-------------------+ | | |
280 | * inactive timer | non contending | | |
281 | * fired +------------------+ | |
282 | * | |
283 | * The task_non_contending() function is invoked when a task | |
284 | * blocks, and checks if the 0-lag time already passed or | |
285 | * not (in the first case, it directly updates running_bw; | |
286 | * in the second case, it arms the inactive timer). | |
287 | * | |
288 | * The task_contending() function is invoked when a task wakes | |
289 | * up, and checks if the task is still in the "ACTIVE non contending" | |
290 | * state or not (in the second case, it updates running_bw). | |
291 | */ | |
292 | static void task_non_contending(struct task_struct *p) | |
293 | { | |
294 | struct sched_dl_entity *dl_se = &p->dl; | |
295 | struct hrtimer *timer = &dl_se->inactive_timer; | |
296 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
297 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
298 | s64 zerolag_time; | |
299 | ||
300 | /* | |
301 | * If this is a non-deadline task that has been boosted, | |
302 | * do nothing | |
303 | */ | |
304 | if (dl_se->dl_runtime == 0) | |
305 | return; | |
306 | ||
794a56eb JL |
307 | if (dl_entity_is_special(dl_se)) |
308 | return; | |
309 | ||
209a0cbd LA |
310 | WARN_ON(dl_se->dl_non_contending); |
311 | ||
312 | zerolag_time = dl_se->deadline - | |
313 | div64_long((dl_se->runtime * dl_se->dl_period), | |
314 | dl_se->dl_runtime); | |
315 | ||
316 | /* | |
317 | * Using relative times instead of the absolute "0-lag time" | |
318 | * allows to simplify the code | |
319 | */ | |
320 | zerolag_time -= rq_clock(rq); | |
321 | ||
322 | /* | |
323 | * If the "0-lag time" already passed, decrease the active | |
324 | * utilization now, instead of starting a timer | |
325 | */ | |
1b02cd6a | 326 | if ((zerolag_time < 0) || hrtimer_active(&dl_se->inactive_timer)) { |
209a0cbd | 327 | if (dl_task(p)) |
794a56eb | 328 | sub_running_bw(dl_se, dl_rq); |
387e3130 LA |
329 | if (!dl_task(p) || p->state == TASK_DEAD) { |
330 | struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); | |
331 | ||
8fd27231 | 332 | if (p->state == TASK_DEAD) |
794a56eb | 333 | sub_rq_bw(&p->dl, &rq->dl); |
387e3130 | 334 | raw_spin_lock(&dl_b->lock); |
8c0944ce | 335 | __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p))); |
209a0cbd | 336 | __dl_clear_params(p); |
387e3130 LA |
337 | raw_spin_unlock(&dl_b->lock); |
338 | } | |
209a0cbd LA |
339 | |
340 | return; | |
341 | } | |
342 | ||
343 | dl_se->dl_non_contending = 1; | |
344 | get_task_struct(p); | |
850377a8 | 345 | hrtimer_start(timer, ns_to_ktime(zerolag_time), HRTIMER_MODE_REL_HARD); |
209a0cbd LA |
346 | } |
347 | ||
8fd27231 | 348 | static void task_contending(struct sched_dl_entity *dl_se, int flags) |
209a0cbd LA |
349 | { |
350 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
351 | ||
352 | /* | |
353 | * If this is a non-deadline task that has been boosted, | |
354 | * do nothing | |
355 | */ | |
356 | if (dl_se->dl_runtime == 0) | |
357 | return; | |
358 | ||
8fd27231 | 359 | if (flags & ENQUEUE_MIGRATED) |
794a56eb | 360 | add_rq_bw(dl_se, dl_rq); |
8fd27231 | 361 | |
209a0cbd LA |
362 | if (dl_se->dl_non_contending) { |
363 | dl_se->dl_non_contending = 0; | |
364 | /* | |
365 | * If the timer handler is currently running and the | |
366 | * timer cannot be cancelled, inactive_task_timer() | |
367 | * will see that dl_not_contending is not set, and | |
368 | * will not touch the rq's active utilization, | |
369 | * so we are still safe. | |
370 | */ | |
371 | if (hrtimer_try_to_cancel(&dl_se->inactive_timer) == 1) | |
372 | put_task_struct(dl_task_of(dl_se)); | |
373 | } else { | |
374 | /* | |
375 | * Since "dl_non_contending" is not set, the | |
376 | * task's utilization has already been removed from | |
377 | * active utilization (either when the task blocked, | |
378 | * when the "inactive timer" fired). | |
379 | * So, add it back. | |
380 | */ | |
794a56eb | 381 | add_running_bw(dl_se, dl_rq); |
209a0cbd LA |
382 | } |
383 | } | |
384 | ||
aab03e05 DF |
385 | static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq) |
386 | { | |
387 | struct sched_dl_entity *dl_se = &p->dl; | |
388 | ||
2161573e | 389 | return dl_rq->root.rb_leftmost == &dl_se->rb_node; |
aab03e05 DF |
390 | } |
391 | ||
ba4f7bc1 YC |
392 | static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq); |
393 | ||
332ac17e DF |
394 | void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime) |
395 | { | |
396 | raw_spin_lock_init(&dl_b->dl_runtime_lock); | |
397 | dl_b->dl_period = period; | |
398 | dl_b->dl_runtime = runtime; | |
399 | } | |
400 | ||
332ac17e DF |
401 | void init_dl_bw(struct dl_bw *dl_b) |
402 | { | |
403 | raw_spin_lock_init(&dl_b->lock); | |
404 | raw_spin_lock(&def_dl_bandwidth.dl_runtime_lock); | |
1724813d | 405 | if (global_rt_runtime() == RUNTIME_INF) |
332ac17e DF |
406 | dl_b->bw = -1; |
407 | else | |
1724813d | 408 | dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime()); |
332ac17e DF |
409 | raw_spin_unlock(&def_dl_bandwidth.dl_runtime_lock); |
410 | dl_b->total_bw = 0; | |
411 | } | |
412 | ||
07c54f7a | 413 | void init_dl_rq(struct dl_rq *dl_rq) |
aab03e05 | 414 | { |
2161573e | 415 | dl_rq->root = RB_ROOT_CACHED; |
1baca4ce JL |
416 | |
417 | #ifdef CONFIG_SMP | |
418 | /* zero means no -deadline tasks */ | |
419 | dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0; | |
420 | ||
421 | dl_rq->dl_nr_migratory = 0; | |
422 | dl_rq->overloaded = 0; | |
2161573e | 423 | dl_rq->pushable_dl_tasks_root = RB_ROOT_CACHED; |
332ac17e DF |
424 | #else |
425 | init_dl_bw(&dl_rq->dl_bw); | |
1baca4ce | 426 | #endif |
e36d8677 LA |
427 | |
428 | dl_rq->running_bw = 0; | |
8fd27231 | 429 | dl_rq->this_bw = 0; |
4da3abce | 430 | init_dl_rq_bw_ratio(dl_rq); |
1baca4ce JL |
431 | } |
432 | ||
433 | #ifdef CONFIG_SMP | |
434 | ||
435 | static inline int dl_overloaded(struct rq *rq) | |
436 | { | |
437 | return atomic_read(&rq->rd->dlo_count); | |
438 | } | |
439 | ||
440 | static inline void dl_set_overload(struct rq *rq) | |
441 | { | |
442 | if (!rq->online) | |
443 | return; | |
444 | ||
445 | cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask); | |
446 | /* | |
447 | * Must be visible before the overload count is | |
448 | * set (as in sched_rt.c). | |
449 | * | |
450 | * Matched by the barrier in pull_dl_task(). | |
451 | */ | |
452 | smp_wmb(); | |
453 | atomic_inc(&rq->rd->dlo_count); | |
454 | } | |
455 | ||
456 | static inline void dl_clear_overload(struct rq *rq) | |
457 | { | |
458 | if (!rq->online) | |
459 | return; | |
460 | ||
461 | atomic_dec(&rq->rd->dlo_count); | |
462 | cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask); | |
463 | } | |
464 | ||
465 | static void update_dl_migration(struct dl_rq *dl_rq) | |
466 | { | |
995b9ea4 | 467 | if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_running > 1) { |
1baca4ce JL |
468 | if (!dl_rq->overloaded) { |
469 | dl_set_overload(rq_of_dl_rq(dl_rq)); | |
470 | dl_rq->overloaded = 1; | |
471 | } | |
472 | } else if (dl_rq->overloaded) { | |
473 | dl_clear_overload(rq_of_dl_rq(dl_rq)); | |
474 | dl_rq->overloaded = 0; | |
475 | } | |
476 | } | |
477 | ||
478 | static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
479 | { | |
480 | struct task_struct *p = dl_task_of(dl_se); | |
1baca4ce | 481 | |
4b53a341 | 482 | if (p->nr_cpus_allowed > 1) |
1baca4ce JL |
483 | dl_rq->dl_nr_migratory++; |
484 | ||
485 | update_dl_migration(dl_rq); | |
486 | } | |
487 | ||
488 | static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
489 | { | |
490 | struct task_struct *p = dl_task_of(dl_se); | |
1baca4ce | 491 | |
4b53a341 | 492 | if (p->nr_cpus_allowed > 1) |
1baca4ce JL |
493 | dl_rq->dl_nr_migratory--; |
494 | ||
495 | update_dl_migration(dl_rq); | |
496 | } | |
497 | ||
498 | /* | |
499 | * The list of pushable -deadline task is not a plist, like in | |
500 | * sched_rt.c, it is an rb-tree with tasks ordered by deadline. | |
501 | */ | |
502 | static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p) | |
503 | { | |
504 | struct dl_rq *dl_rq = &rq->dl; | |
2161573e | 505 | struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_root.rb_node; |
1baca4ce JL |
506 | struct rb_node *parent = NULL; |
507 | struct task_struct *entry; | |
2161573e | 508 | bool leftmost = true; |
1baca4ce JL |
509 | |
510 | BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks)); | |
511 | ||
512 | while (*link) { | |
513 | parent = *link; | |
514 | entry = rb_entry(parent, struct task_struct, | |
515 | pushable_dl_tasks); | |
516 | if (dl_entity_preempt(&p->dl, &entry->dl)) | |
517 | link = &parent->rb_left; | |
518 | else { | |
519 | link = &parent->rb_right; | |
2161573e | 520 | leftmost = false; |
1baca4ce JL |
521 | } |
522 | } | |
523 | ||
2161573e | 524 | if (leftmost) |
7d92de3a | 525 | dl_rq->earliest_dl.next = p->dl.deadline; |
1baca4ce JL |
526 | |
527 | rb_link_node(&p->pushable_dl_tasks, parent, link); | |
2161573e DB |
528 | rb_insert_color_cached(&p->pushable_dl_tasks, |
529 | &dl_rq->pushable_dl_tasks_root, leftmost); | |
aab03e05 DF |
530 | } |
531 | ||
1baca4ce JL |
532 | static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p) |
533 | { | |
534 | struct dl_rq *dl_rq = &rq->dl; | |
535 | ||
536 | if (RB_EMPTY_NODE(&p->pushable_dl_tasks)) | |
537 | return; | |
538 | ||
2161573e | 539 | if (dl_rq->pushable_dl_tasks_root.rb_leftmost == &p->pushable_dl_tasks) { |
1baca4ce JL |
540 | struct rb_node *next_node; |
541 | ||
542 | next_node = rb_next(&p->pushable_dl_tasks); | |
7d92de3a WL |
543 | if (next_node) { |
544 | dl_rq->earliest_dl.next = rb_entry(next_node, | |
545 | struct task_struct, pushable_dl_tasks)->dl.deadline; | |
546 | } | |
1baca4ce JL |
547 | } |
548 | ||
2161573e | 549 | rb_erase_cached(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root); |
1baca4ce JL |
550 | RB_CLEAR_NODE(&p->pushable_dl_tasks); |
551 | } | |
552 | ||
553 | static inline int has_pushable_dl_tasks(struct rq *rq) | |
554 | { | |
2161573e | 555 | return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root.rb_root); |
1baca4ce JL |
556 | } |
557 | ||
558 | static int push_dl_task(struct rq *rq); | |
559 | ||
dc877341 PZ |
560 | static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) |
561 | { | |
562 | return dl_task(prev); | |
563 | } | |
564 | ||
9916e214 PZ |
565 | static DEFINE_PER_CPU(struct callback_head, dl_push_head); |
566 | static DEFINE_PER_CPU(struct callback_head, dl_pull_head); | |
e3fca9e7 PZ |
567 | |
568 | static void push_dl_tasks(struct rq *); | |
9916e214 | 569 | static void pull_dl_task(struct rq *); |
e3fca9e7 | 570 | |
02d8ec94 | 571 | static inline void deadline_queue_push_tasks(struct rq *rq) |
dc877341 | 572 | { |
e3fca9e7 PZ |
573 | if (!has_pushable_dl_tasks(rq)) |
574 | return; | |
575 | ||
9916e214 PZ |
576 | queue_balance_callback(rq, &per_cpu(dl_push_head, rq->cpu), push_dl_tasks); |
577 | } | |
578 | ||
02d8ec94 | 579 | static inline void deadline_queue_pull_task(struct rq *rq) |
9916e214 PZ |
580 | { |
581 | queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task); | |
dc877341 PZ |
582 | } |
583 | ||
fa9c9d10 WL |
584 | static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq); |
585 | ||
a649f237 | 586 | static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p) |
fa9c9d10 WL |
587 | { |
588 | struct rq *later_rq = NULL; | |
59d06cea | 589 | struct dl_bw *dl_b; |
fa9c9d10 WL |
590 | |
591 | later_rq = find_lock_later_rq(p, rq); | |
fa9c9d10 WL |
592 | if (!later_rq) { |
593 | int cpu; | |
594 | ||
595 | /* | |
596 | * If we cannot preempt any rq, fall back to pick any | |
97fb7a0a | 597 | * online CPU: |
fa9c9d10 | 598 | */ |
3bd37062 | 599 | cpu = cpumask_any_and(cpu_active_mask, p->cpus_ptr); |
fa9c9d10 WL |
600 | if (cpu >= nr_cpu_ids) { |
601 | /* | |
97fb7a0a | 602 | * Failed to find any suitable CPU. |
fa9c9d10 WL |
603 | * The task will never come back! |
604 | */ | |
605 | BUG_ON(dl_bandwidth_enabled()); | |
606 | ||
607 | /* | |
608 | * If admission control is disabled we | |
609 | * try a little harder to let the task | |
610 | * run. | |
611 | */ | |
612 | cpu = cpumask_any(cpu_active_mask); | |
613 | } | |
614 | later_rq = cpu_rq(cpu); | |
615 | double_lock_balance(rq, later_rq); | |
616 | } | |
617 | ||
59d06cea JL |
618 | if (p->dl.dl_non_contending || p->dl.dl_throttled) { |
619 | /* | |
620 | * Inactive timer is armed (or callback is running, but | |
621 | * waiting for us to release rq locks). In any case, when it | |
622 | * will fire (or continue), it will see running_bw of this | |
623 | * task migrated to later_rq (and correctly handle it). | |
624 | */ | |
625 | sub_running_bw(&p->dl, &rq->dl); | |
626 | sub_rq_bw(&p->dl, &rq->dl); | |
627 | ||
628 | add_rq_bw(&p->dl, &later_rq->dl); | |
629 | add_running_bw(&p->dl, &later_rq->dl); | |
630 | } else { | |
631 | sub_rq_bw(&p->dl, &rq->dl); | |
632 | add_rq_bw(&p->dl, &later_rq->dl); | |
633 | } | |
634 | ||
635 | /* | |
636 | * And we finally need to fixup root_domain(s) bandwidth accounting, | |
637 | * since p is still hanging out in the old (now moved to default) root | |
638 | * domain. | |
639 | */ | |
640 | dl_b = &rq->rd->dl_bw; | |
641 | raw_spin_lock(&dl_b->lock); | |
642 | __dl_sub(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span)); | |
643 | raw_spin_unlock(&dl_b->lock); | |
644 | ||
645 | dl_b = &later_rq->rd->dl_bw; | |
646 | raw_spin_lock(&dl_b->lock); | |
647 | __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(later_rq->rd->span)); | |
648 | raw_spin_unlock(&dl_b->lock); | |
649 | ||
fa9c9d10 | 650 | set_task_cpu(p, later_rq->cpu); |
a649f237 PZ |
651 | double_unlock_balance(later_rq, rq); |
652 | ||
653 | return later_rq; | |
fa9c9d10 WL |
654 | } |
655 | ||
1baca4ce JL |
656 | #else |
657 | ||
658 | static inline | |
659 | void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p) | |
660 | { | |
661 | } | |
662 | ||
663 | static inline | |
664 | void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p) | |
665 | { | |
666 | } | |
667 | ||
668 | static inline | |
669 | void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
670 | { | |
671 | } | |
672 | ||
673 | static inline | |
674 | void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
675 | { | |
676 | } | |
677 | ||
dc877341 PZ |
678 | static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) |
679 | { | |
680 | return false; | |
681 | } | |
682 | ||
0ea60c20 | 683 | static inline void pull_dl_task(struct rq *rq) |
dc877341 | 684 | { |
dc877341 PZ |
685 | } |
686 | ||
02d8ec94 | 687 | static inline void deadline_queue_push_tasks(struct rq *rq) |
dc877341 | 688 | { |
dc877341 PZ |
689 | } |
690 | ||
02d8ec94 | 691 | static inline void deadline_queue_pull_task(struct rq *rq) |
dc877341 PZ |
692 | { |
693 | } | |
1baca4ce JL |
694 | #endif /* CONFIG_SMP */ |
695 | ||
aab03e05 DF |
696 | static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags); |
697 | static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags); | |
97fb7a0a | 698 | static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, int flags); |
aab03e05 DF |
699 | |
700 | /* | |
701 | * We are being explicitly informed that a new instance is starting, | |
702 | * and this means that: | |
703 | * - the absolute deadline of the entity has to be placed at | |
704 | * current time + relative deadline; | |
705 | * - the runtime of the entity has to be set to the maximum value. | |
706 | * | |
707 | * The capability of specifying such event is useful whenever a -deadline | |
708 | * entity wants to (try to!) synchronize its behaviour with the scheduler's | |
709 | * one, and to (try to!) reconcile itself with its own scheduling | |
710 | * parameters. | |
711 | */ | |
98b0a857 | 712 | static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) |
aab03e05 DF |
713 | { |
714 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
715 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
716 | ||
98b0a857 | 717 | WARN_ON(dl_se->dl_boosted); |
72f9f3fd LA |
718 | WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline)); |
719 | ||
720 | /* | |
721 | * We are racing with the deadline timer. So, do nothing because | |
722 | * the deadline timer handler will take care of properly recharging | |
723 | * the runtime and postponing the deadline | |
724 | */ | |
725 | if (dl_se->dl_throttled) | |
726 | return; | |
aab03e05 DF |
727 | |
728 | /* | |
729 | * We use the regular wall clock time to set deadlines in the | |
730 | * future; in fact, we must consider execution overheads (time | |
731 | * spent on hardirq context, etc.). | |
732 | */ | |
98b0a857 JL |
733 | dl_se->deadline = rq_clock(rq) + dl_se->dl_deadline; |
734 | dl_se->runtime = dl_se->dl_runtime; | |
aab03e05 DF |
735 | } |
736 | ||
737 | /* | |
738 | * Pure Earliest Deadline First (EDF) scheduling does not deal with the | |
739 | * possibility of a entity lasting more than what it declared, and thus | |
740 | * exhausting its runtime. | |
741 | * | |
742 | * Here we are interested in making runtime overrun possible, but we do | |
743 | * not want a entity which is misbehaving to affect the scheduling of all | |
744 | * other entities. | |
745 | * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS) | |
746 | * is used, in order to confine each entity within its own bandwidth. | |
747 | * | |
748 | * This function deals exactly with that, and ensures that when the runtime | |
749 | * of a entity is replenished, its deadline is also postponed. That ensures | |
750 | * the overrunning entity can't interfere with other entity in the system and | |
751 | * can't make them miss their deadlines. Reasons why this kind of overruns | |
752 | * could happen are, typically, a entity voluntarily trying to overcome its | |
1b09d29b | 753 | * runtime, or it just underestimated it during sched_setattr(). |
aab03e05 | 754 | */ |
2d3d891d DF |
755 | static void replenish_dl_entity(struct sched_dl_entity *dl_se, |
756 | struct sched_dl_entity *pi_se) | |
aab03e05 DF |
757 | { |
758 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
759 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
760 | ||
2d3d891d DF |
761 | BUG_ON(pi_se->dl_runtime <= 0); |
762 | ||
763 | /* | |
764 | * This could be the case for a !-dl task that is boosted. | |
765 | * Just go with full inherited parameters. | |
766 | */ | |
767 | if (dl_se->dl_deadline == 0) { | |
768 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; | |
769 | dl_se->runtime = pi_se->dl_runtime; | |
770 | } | |
771 | ||
48be3a67 PZ |
772 | if (dl_se->dl_yielded && dl_se->runtime > 0) |
773 | dl_se->runtime = 0; | |
774 | ||
aab03e05 DF |
775 | /* |
776 | * We keep moving the deadline away until we get some | |
777 | * available runtime for the entity. This ensures correct | |
778 | * handling of situations where the runtime overrun is | |
779 | * arbitrary large. | |
780 | */ | |
781 | while (dl_se->runtime <= 0) { | |
2d3d891d DF |
782 | dl_se->deadline += pi_se->dl_period; |
783 | dl_se->runtime += pi_se->dl_runtime; | |
aab03e05 DF |
784 | } |
785 | ||
786 | /* | |
787 | * At this point, the deadline really should be "in | |
788 | * the future" with respect to rq->clock. If it's | |
789 | * not, we are, for some reason, lagging too much! | |
790 | * Anyway, after having warn userspace abut that, | |
791 | * we still try to keep the things running by | |
792 | * resetting the deadline and the budget of the | |
793 | * entity. | |
794 | */ | |
795 | if (dl_time_before(dl_se->deadline, rq_clock(rq))) { | |
c219b7dd | 796 | printk_deferred_once("sched: DL replenish lagged too much\n"); |
2d3d891d DF |
797 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; |
798 | dl_se->runtime = pi_se->dl_runtime; | |
aab03e05 | 799 | } |
1019a359 PZ |
800 | |
801 | if (dl_se->dl_yielded) | |
802 | dl_se->dl_yielded = 0; | |
803 | if (dl_se->dl_throttled) | |
804 | dl_se->dl_throttled = 0; | |
aab03e05 DF |
805 | } |
806 | ||
807 | /* | |
808 | * Here we check if --at time t-- an entity (which is probably being | |
809 | * [re]activated or, in general, enqueued) can use its remaining runtime | |
810 | * and its current deadline _without_ exceeding the bandwidth it is | |
811 | * assigned (function returns true if it can't). We are in fact applying | |
812 | * one of the CBS rules: when a task wakes up, if the residual runtime | |
813 | * over residual deadline fits within the allocated bandwidth, then we | |
814 | * can keep the current (absolute) deadline and residual budget without | |
815 | * disrupting the schedulability of the system. Otherwise, we should | |
816 | * refill the runtime and set the deadline a period in the future, | |
817 | * because keeping the current (absolute) deadline of the task would | |
712e5e34 | 818 | * result in breaking guarantees promised to other tasks (refer to |
d6a3b247 | 819 | * Documentation/scheduler/sched-deadline.rst for more information). |
aab03e05 DF |
820 | * |
821 | * This function returns true if: | |
822 | * | |
2317d5f1 | 823 | * runtime / (deadline - t) > dl_runtime / dl_deadline , |
aab03e05 DF |
824 | * |
825 | * IOW we can't recycle current parameters. | |
755378a4 | 826 | * |
2317d5f1 | 827 | * Notice that the bandwidth check is done against the deadline. For |
755378a4 | 828 | * task with deadline equal to period this is the same of using |
2317d5f1 | 829 | * dl_period instead of dl_deadline in the equation above. |
aab03e05 | 830 | */ |
2d3d891d DF |
831 | static bool dl_entity_overflow(struct sched_dl_entity *dl_se, |
832 | struct sched_dl_entity *pi_se, u64 t) | |
aab03e05 DF |
833 | { |
834 | u64 left, right; | |
835 | ||
836 | /* | |
837 | * left and right are the two sides of the equation above, | |
838 | * after a bit of shuffling to use multiplications instead | |
839 | * of divisions. | |
840 | * | |
841 | * Note that none of the time values involved in the two | |
842 | * multiplications are absolute: dl_deadline and dl_runtime | |
843 | * are the relative deadline and the maximum runtime of each | |
844 | * instance, runtime is the runtime left for the last instance | |
845 | * and (deadline - t), since t is rq->clock, is the time left | |
846 | * to the (absolute) deadline. Even if overflowing the u64 type | |
847 | * is very unlikely to occur in both cases, here we scale down | |
848 | * as we want to avoid that risk at all. Scaling down by 10 | |
849 | * means that we reduce granularity to 1us. We are fine with it, | |
850 | * since this is only a true/false check and, anyway, thinking | |
851 | * of anything below microseconds resolution is actually fiction | |
852 | * (but still we want to give the user that illusion >;). | |
853 | */ | |
2317d5f1 | 854 | left = (pi_se->dl_deadline >> DL_SCALE) * (dl_se->runtime >> DL_SCALE); |
332ac17e DF |
855 | right = ((dl_se->deadline - t) >> DL_SCALE) * |
856 | (pi_se->dl_runtime >> DL_SCALE); | |
aab03e05 DF |
857 | |
858 | return dl_time_before(right, left); | |
859 | } | |
860 | ||
861 | /* | |
3effcb42 DBO |
862 | * Revised wakeup rule [1]: For self-suspending tasks, rather then |
863 | * re-initializing task's runtime and deadline, the revised wakeup | |
864 | * rule adjusts the task's runtime to avoid the task to overrun its | |
865 | * density. | |
aab03e05 | 866 | * |
3effcb42 DBO |
867 | * Reasoning: a task may overrun the density if: |
868 | * runtime / (deadline - t) > dl_runtime / dl_deadline | |
869 | * | |
870 | * Therefore, runtime can be adjusted to: | |
871 | * runtime = (dl_runtime / dl_deadline) * (deadline - t) | |
872 | * | |
873 | * In such way that runtime will be equal to the maximum density | |
874 | * the task can use without breaking any rule. | |
875 | * | |
876 | * [1] Luca Abeni, Giuseppe Lipari, and Juri Lelli. 2015. Constant | |
877 | * bandwidth server revisited. SIGBED Rev. 11, 4 (January 2015), 19-24. | |
878 | */ | |
879 | static void | |
880 | update_dl_revised_wakeup(struct sched_dl_entity *dl_se, struct rq *rq) | |
881 | { | |
882 | u64 laxity = dl_se->deadline - rq_clock(rq); | |
883 | ||
884 | /* | |
885 | * If the task has deadline < period, and the deadline is in the past, | |
886 | * it should already be throttled before this check. | |
887 | * | |
888 | * See update_dl_entity() comments for further details. | |
889 | */ | |
890 | WARN_ON(dl_time_before(dl_se->deadline, rq_clock(rq))); | |
891 | ||
892 | dl_se->runtime = (dl_se->dl_density * laxity) >> BW_SHIFT; | |
893 | } | |
894 | ||
895 | /* | |
896 | * Regarding the deadline, a task with implicit deadline has a relative | |
897 | * deadline == relative period. A task with constrained deadline has a | |
898 | * relative deadline <= relative period. | |
899 | * | |
900 | * We support constrained deadline tasks. However, there are some restrictions | |
901 | * applied only for tasks which do not have an implicit deadline. See | |
902 | * update_dl_entity() to know more about such restrictions. | |
903 | * | |
904 | * The dl_is_implicit() returns true if the task has an implicit deadline. | |
905 | */ | |
906 | static inline bool dl_is_implicit(struct sched_dl_entity *dl_se) | |
907 | { | |
908 | return dl_se->dl_deadline == dl_se->dl_period; | |
909 | } | |
910 | ||
911 | /* | |
912 | * When a deadline entity is placed in the runqueue, its runtime and deadline | |
913 | * might need to be updated. This is done by a CBS wake up rule. There are two | |
914 | * different rules: 1) the original CBS; and 2) the Revisited CBS. | |
915 | * | |
916 | * When the task is starting a new period, the Original CBS is used. In this | |
917 | * case, the runtime is replenished and a new absolute deadline is set. | |
918 | * | |
919 | * When a task is queued before the begin of the next period, using the | |
920 | * remaining runtime and deadline could make the entity to overflow, see | |
921 | * dl_entity_overflow() to find more about runtime overflow. When such case | |
922 | * is detected, the runtime and deadline need to be updated. | |
923 | * | |
924 | * If the task has an implicit deadline, i.e., deadline == period, the Original | |
925 | * CBS is applied. the runtime is replenished and a new absolute deadline is | |
926 | * set, as in the previous cases. | |
927 | * | |
928 | * However, the Original CBS does not work properly for tasks with | |
929 | * deadline < period, which are said to have a constrained deadline. By | |
930 | * applying the Original CBS, a constrained deadline task would be able to run | |
931 | * runtime/deadline in a period. With deadline < period, the task would | |
932 | * overrun the runtime/period allowed bandwidth, breaking the admission test. | |
933 | * | |
934 | * In order to prevent this misbehave, the Revisited CBS is used for | |
935 | * constrained deadline tasks when a runtime overflow is detected. In the | |
936 | * Revisited CBS, rather than replenishing & setting a new absolute deadline, | |
937 | * the remaining runtime of the task is reduced to avoid runtime overflow. | |
938 | * Please refer to the comments update_dl_revised_wakeup() function to find | |
939 | * more about the Revised CBS rule. | |
aab03e05 | 940 | */ |
2d3d891d DF |
941 | static void update_dl_entity(struct sched_dl_entity *dl_se, |
942 | struct sched_dl_entity *pi_se) | |
aab03e05 DF |
943 | { |
944 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
945 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
946 | ||
aab03e05 | 947 | if (dl_time_before(dl_se->deadline, rq_clock(rq)) || |
2d3d891d | 948 | dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) { |
3effcb42 DBO |
949 | |
950 | if (unlikely(!dl_is_implicit(dl_se) && | |
951 | !dl_time_before(dl_se->deadline, rq_clock(rq)) && | |
952 | !dl_se->dl_boosted)){ | |
953 | update_dl_revised_wakeup(dl_se, rq); | |
954 | return; | |
955 | } | |
956 | ||
2d3d891d DF |
957 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; |
958 | dl_se->runtime = pi_se->dl_runtime; | |
aab03e05 DF |
959 | } |
960 | } | |
961 | ||
5ac69d37 DBO |
962 | static inline u64 dl_next_period(struct sched_dl_entity *dl_se) |
963 | { | |
964 | return dl_se->deadline - dl_se->dl_deadline + dl_se->dl_period; | |
965 | } | |
966 | ||
aab03e05 DF |
967 | /* |
968 | * If the entity depleted all its runtime, and if we want it to sleep | |
969 | * while waiting for some new execution time to become available, we | |
5ac69d37 | 970 | * set the bandwidth replenishment timer to the replenishment instant |
aab03e05 DF |
971 | * and try to activate it. |
972 | * | |
973 | * Notice that it is important for the caller to know if the timer | |
974 | * actually started or not (i.e., the replenishment instant is in | |
975 | * the future or in the past). | |
976 | */ | |
a649f237 | 977 | static int start_dl_timer(struct task_struct *p) |
aab03e05 | 978 | { |
a649f237 PZ |
979 | struct sched_dl_entity *dl_se = &p->dl; |
980 | struct hrtimer *timer = &dl_se->dl_timer; | |
981 | struct rq *rq = task_rq(p); | |
aab03e05 | 982 | ktime_t now, act; |
aab03e05 DF |
983 | s64 delta; |
984 | ||
a649f237 PZ |
985 | lockdep_assert_held(&rq->lock); |
986 | ||
aab03e05 DF |
987 | /* |
988 | * We want the timer to fire at the deadline, but considering | |
989 | * that it is actually coming from rq->clock and not from | |
990 | * hrtimer's time base reading. | |
991 | */ | |
5ac69d37 | 992 | act = ns_to_ktime(dl_next_period(dl_se)); |
a649f237 | 993 | now = hrtimer_cb_get_time(timer); |
aab03e05 DF |
994 | delta = ktime_to_ns(now) - rq_clock(rq); |
995 | act = ktime_add_ns(act, delta); | |
996 | ||
997 | /* | |
998 | * If the expiry time already passed, e.g., because the value | |
999 | * chosen as the deadline is too small, don't even try to | |
1000 | * start the timer in the past! | |
1001 | */ | |
1002 | if (ktime_us_delta(act, now) < 0) | |
1003 | return 0; | |
1004 | ||
a649f237 PZ |
1005 | /* |
1006 | * !enqueued will guarantee another callback; even if one is already in | |
1007 | * progress. This ensures a balanced {get,put}_task_struct(). | |
1008 | * | |
1009 | * The race against __run_timer() clearing the enqueued state is | |
1010 | * harmless because we're holding task_rq()->lock, therefore the timer | |
1011 | * expiring after we've done the check will wait on its task_rq_lock() | |
1012 | * and observe our state. | |
1013 | */ | |
1014 | if (!hrtimer_is_queued(timer)) { | |
1015 | get_task_struct(p); | |
d5096aa6 | 1016 | hrtimer_start(timer, act, HRTIMER_MODE_ABS_HARD); |
a649f237 | 1017 | } |
aab03e05 | 1018 | |
cc9684d3 | 1019 | return 1; |
aab03e05 DF |
1020 | } |
1021 | ||
1022 | /* | |
1023 | * This is the bandwidth enforcement timer callback. If here, we know | |
1024 | * a task is not on its dl_rq, since the fact that the timer was running | |
1025 | * means the task is throttled and needs a runtime replenishment. | |
1026 | * | |
1027 | * However, what we actually do depends on the fact the task is active, | |
1028 | * (it is on its rq) or has been removed from there by a call to | |
1029 | * dequeue_task_dl(). In the former case we must issue the runtime | |
1030 | * replenishment and add the task back to the dl_rq; in the latter, we just | |
1031 | * do nothing but clearing dl_throttled, so that runtime and deadline | |
1032 | * updating (and the queueing back to dl_rq) will be done by the | |
1033 | * next call to enqueue_task_dl(). | |
1034 | */ | |
1035 | static enum hrtimer_restart dl_task_timer(struct hrtimer *timer) | |
1036 | { | |
1037 | struct sched_dl_entity *dl_se = container_of(timer, | |
1038 | struct sched_dl_entity, | |
1039 | dl_timer); | |
1040 | struct task_struct *p = dl_task_of(dl_se); | |
eb580751 | 1041 | struct rq_flags rf; |
0f397f2c | 1042 | struct rq *rq; |
3960c8c0 | 1043 | |
eb580751 | 1044 | rq = task_rq_lock(p, &rf); |
0f397f2c | 1045 | |
aab03e05 | 1046 | /* |
a649f237 | 1047 | * The task might have changed its scheduling policy to something |
9846d50d | 1048 | * different than SCHED_DEADLINE (through switched_from_dl()). |
a649f237 | 1049 | */ |
209a0cbd | 1050 | if (!dl_task(p)) |
a649f237 | 1051 | goto unlock; |
a649f237 | 1052 | |
a649f237 PZ |
1053 | /* |
1054 | * The task might have been boosted by someone else and might be in the | |
1055 | * boosting/deboosting path, its not throttled. | |
1056 | */ | |
1057 | if (dl_se->dl_boosted) | |
1058 | goto unlock; | |
a79ec89f | 1059 | |
fa9c9d10 | 1060 | /* |
a649f237 PZ |
1061 | * Spurious timer due to start_dl_timer() race; or we already received |
1062 | * a replenishment from rt_mutex_setprio(). | |
fa9c9d10 | 1063 | */ |
a649f237 | 1064 | if (!dl_se->dl_throttled) |
fa9c9d10 | 1065 | goto unlock; |
a649f237 PZ |
1066 | |
1067 | sched_clock_tick(); | |
1068 | update_rq_clock(rq); | |
fa9c9d10 | 1069 | |
a79ec89f KT |
1070 | /* |
1071 | * If the throttle happened during sched-out; like: | |
1072 | * | |
1073 | * schedule() | |
1074 | * deactivate_task() | |
1075 | * dequeue_task_dl() | |
1076 | * update_curr_dl() | |
1077 | * start_dl_timer() | |
1078 | * __dequeue_task_dl() | |
1079 | * prev->on_rq = 0; | |
1080 | * | |
1081 | * We can be both throttled and !queued. Replenish the counter | |
1082 | * but do not enqueue -- wait for our wakeup to do that. | |
1083 | */ | |
1084 | if (!task_on_rq_queued(p)) { | |
1085 | replenish_dl_entity(dl_se, dl_se); | |
1086 | goto unlock; | |
1087 | } | |
1088 | ||
1baca4ce | 1089 | #ifdef CONFIG_SMP |
c0c8c9fa | 1090 | if (unlikely(!rq->online)) { |
61c7aca6 WL |
1091 | /* |
1092 | * If the runqueue is no longer available, migrate the | |
1093 | * task elsewhere. This necessarily changes rq. | |
1094 | */ | |
c0c8c9fa | 1095 | lockdep_unpin_lock(&rq->lock, rf.cookie); |
a649f237 | 1096 | rq = dl_task_offline_migration(rq, p); |
c0c8c9fa | 1097 | rf.cookie = lockdep_pin_lock(&rq->lock); |
dcc3b5ff | 1098 | update_rq_clock(rq); |
61c7aca6 WL |
1099 | |
1100 | /* | |
1101 | * Now that the task has been migrated to the new RQ and we | |
1102 | * have that locked, proceed as normal and enqueue the task | |
1103 | * there. | |
1104 | */ | |
c0c8c9fa | 1105 | } |
61c7aca6 | 1106 | #endif |
a649f237 | 1107 | |
61c7aca6 WL |
1108 | enqueue_task_dl(rq, p, ENQUEUE_REPLENISH); |
1109 | if (dl_task(rq->curr)) | |
1110 | check_preempt_curr_dl(rq, p, 0); | |
1111 | else | |
1112 | resched_curr(rq); | |
a649f237 | 1113 | |
61c7aca6 | 1114 | #ifdef CONFIG_SMP |
a649f237 PZ |
1115 | /* |
1116 | * Queueing this task back might have overloaded rq, check if we need | |
1117 | * to kick someone away. | |
1019a359 | 1118 | */ |
0aaafaab PZ |
1119 | if (has_pushable_dl_tasks(rq)) { |
1120 | /* | |
1121 | * Nothing relies on rq->lock after this, so its safe to drop | |
1122 | * rq->lock. | |
1123 | */ | |
d8ac8971 | 1124 | rq_unpin_lock(rq, &rf); |
1019a359 | 1125 | push_dl_task(rq); |
d8ac8971 | 1126 | rq_repin_lock(rq, &rf); |
0aaafaab | 1127 | } |
1baca4ce | 1128 | #endif |
a649f237 | 1129 | |
aab03e05 | 1130 | unlock: |
eb580751 | 1131 | task_rq_unlock(rq, p, &rf); |
aab03e05 | 1132 | |
a649f237 PZ |
1133 | /* |
1134 | * This can free the task_struct, including this hrtimer, do not touch | |
1135 | * anything related to that after this. | |
1136 | */ | |
1137 | put_task_struct(p); | |
1138 | ||
aab03e05 DF |
1139 | return HRTIMER_NORESTART; |
1140 | } | |
1141 | ||
1142 | void init_dl_task_timer(struct sched_dl_entity *dl_se) | |
1143 | { | |
1144 | struct hrtimer *timer = &dl_se->dl_timer; | |
1145 | ||
d5096aa6 | 1146 | hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); |
aab03e05 DF |
1147 | timer->function = dl_task_timer; |
1148 | } | |
1149 | ||
df8eac8c DBO |
1150 | /* |
1151 | * During the activation, CBS checks if it can reuse the current task's | |
1152 | * runtime and period. If the deadline of the task is in the past, CBS | |
1153 | * cannot use the runtime, and so it replenishes the task. This rule | |
1154 | * works fine for implicit deadline tasks (deadline == period), and the | |
1155 | * CBS was designed for implicit deadline tasks. However, a task with | |
c4969417 | 1156 | * constrained deadline (deadline < period) might be awakened after the |
df8eac8c DBO |
1157 | * deadline, but before the next period. In this case, replenishing the |
1158 | * task would allow it to run for runtime / deadline. As in this case | |
1159 | * deadline < period, CBS enables a task to run for more than the | |
1160 | * runtime / period. In a very loaded system, this can cause a domino | |
1161 | * effect, making other tasks miss their deadlines. | |
1162 | * | |
1163 | * To avoid this problem, in the activation of a constrained deadline | |
1164 | * task after the deadline but before the next period, throttle the | |
1165 | * task and set the replenishing timer to the begin of the next period, | |
1166 | * unless it is boosted. | |
1167 | */ | |
1168 | static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se) | |
1169 | { | |
1170 | struct task_struct *p = dl_task_of(dl_se); | |
1171 | struct rq *rq = rq_of_dl_rq(dl_rq_of_se(dl_se)); | |
1172 | ||
1173 | if (dl_time_before(dl_se->deadline, rq_clock(rq)) && | |
1174 | dl_time_before(rq_clock(rq), dl_next_period(dl_se))) { | |
1175 | if (unlikely(dl_se->dl_boosted || !start_dl_timer(p))) | |
1176 | return; | |
1177 | dl_se->dl_throttled = 1; | |
ae83b56a XP |
1178 | if (dl_se->runtime > 0) |
1179 | dl_se->runtime = 0; | |
df8eac8c DBO |
1180 | } |
1181 | } | |
1182 | ||
aab03e05 | 1183 | static |
6fab5410 | 1184 | int dl_runtime_exceeded(struct sched_dl_entity *dl_se) |
aab03e05 | 1185 | { |
269ad801 | 1186 | return (dl_se->runtime <= 0); |
aab03e05 DF |
1187 | } |
1188 | ||
faa59937 JL |
1189 | extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq); |
1190 | ||
c52f14d3 LA |
1191 | /* |
1192 | * This function implements the GRUB accounting rule: | |
1193 | * according to the GRUB reclaiming algorithm, the runtime is | |
daec5798 LA |
1194 | * not decreased as "dq = -dt", but as |
1195 | * "dq = -max{u / Umax, (1 - Uinact - Uextra)} dt", | |
1196 | * where u is the utilization of the task, Umax is the maximum reclaimable | |
1197 | * utilization, Uinact is the (per-runqueue) inactive utilization, computed | |
1198 | * as the difference between the "total runqueue utilization" and the | |
1199 | * runqueue active utilization, and Uextra is the (per runqueue) extra | |
1200 | * reclaimable utilization. | |
9f0d1a50 | 1201 | * Since rq->dl.running_bw and rq->dl.this_bw contain utilizations |
daec5798 LA |
1202 | * multiplied by 2^BW_SHIFT, the result has to be shifted right by |
1203 | * BW_SHIFT. | |
1204 | * Since rq->dl.bw_ratio contains 1 / Umax multipled by 2^RATIO_SHIFT, | |
1205 | * dl_bw is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT. | |
1206 | * Since delta is a 64 bit variable, to have an overflow its value | |
1207 | * should be larger than 2^(64 - 20 - 8), which is more than 64 seconds. | |
1208 | * So, overflow is not an issue here. | |
c52f14d3 | 1209 | */ |
3febfc8a | 1210 | static u64 grub_reclaim(u64 delta, struct rq *rq, struct sched_dl_entity *dl_se) |
c52f14d3 | 1211 | { |
9f0d1a50 LA |
1212 | u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */ |
1213 | u64 u_act; | |
daec5798 | 1214 | u64 u_act_min = (dl_se->dl_bw * rq->dl.bw_ratio) >> RATIO_SHIFT; |
c52f14d3 | 1215 | |
9f0d1a50 | 1216 | /* |
daec5798 LA |
1217 | * Instead of computing max{u * bw_ratio, (1 - u_inact - u_extra)}, |
1218 | * we compare u_inact + rq->dl.extra_bw with | |
1219 | * 1 - (u * rq->dl.bw_ratio >> RATIO_SHIFT), because | |
1220 | * u_inact + rq->dl.extra_bw can be larger than | |
1221 | * 1 * (so, 1 - u_inact - rq->dl.extra_bw would be negative | |
1222 | * leading to wrong results) | |
9f0d1a50 | 1223 | */ |
daec5798 LA |
1224 | if (u_inact + rq->dl.extra_bw > BW_UNIT - u_act_min) |
1225 | u_act = u_act_min; | |
9f0d1a50 | 1226 | else |
daec5798 | 1227 | u_act = BW_UNIT - u_inact - rq->dl.extra_bw; |
9f0d1a50 LA |
1228 | |
1229 | return (delta * u_act) >> BW_SHIFT; | |
c52f14d3 LA |
1230 | } |
1231 | ||
aab03e05 DF |
1232 | /* |
1233 | * Update the current task's runtime statistics (provided it is still | |
1234 | * a -deadline task and has not been removed from the dl_rq). | |
1235 | */ | |
1236 | static void update_curr_dl(struct rq *rq) | |
1237 | { | |
1238 | struct task_struct *curr = rq->curr; | |
1239 | struct sched_dl_entity *dl_se = &curr->dl; | |
07881166 JL |
1240 | u64 delta_exec, scaled_delta_exec; |
1241 | int cpu = cpu_of(rq); | |
6fe0ce1e | 1242 | u64 now; |
aab03e05 DF |
1243 | |
1244 | if (!dl_task(curr) || !on_dl_rq(dl_se)) | |
1245 | return; | |
1246 | ||
1247 | /* | |
1248 | * Consumed budget is computed considering the time as | |
1249 | * observed by schedulable tasks (excluding time spent | |
1250 | * in hardirq context, etc.). Deadlines are instead | |
1251 | * computed using hard walltime. This seems to be the more | |
1252 | * natural solution, but the full ramifications of this | |
1253 | * approach need further study. | |
1254 | */ | |
6fe0ce1e WY |
1255 | now = rq_clock_task(rq); |
1256 | delta_exec = now - curr->se.exec_start; | |
48be3a67 PZ |
1257 | if (unlikely((s64)delta_exec <= 0)) { |
1258 | if (unlikely(dl_se->dl_yielded)) | |
1259 | goto throttle; | |
734ff2a7 | 1260 | return; |
48be3a67 | 1261 | } |
aab03e05 DF |
1262 | |
1263 | schedstat_set(curr->se.statistics.exec_max, | |
1264 | max(curr->se.statistics.exec_max, delta_exec)); | |
1265 | ||
1266 | curr->se.sum_exec_runtime += delta_exec; | |
1267 | account_group_exec_runtime(curr, delta_exec); | |
1268 | ||
6fe0ce1e | 1269 | curr->se.exec_start = now; |
d2cc5ed6 | 1270 | cgroup_account_cputime(curr, delta_exec); |
aab03e05 | 1271 | |
794a56eb JL |
1272 | if (dl_entity_is_special(dl_se)) |
1273 | return; | |
1274 | ||
07881166 JL |
1275 | /* |
1276 | * For tasks that participate in GRUB, we implement GRUB-PA: the | |
1277 | * spare reclaimed bandwidth is used to clock down frequency. | |
1278 | * | |
1279 | * For the others, we still need to scale reservation parameters | |
1280 | * according to current frequency and CPU maximum capacity. | |
1281 | */ | |
1282 | if (unlikely(dl_se->flags & SCHED_FLAG_RECLAIM)) { | |
1283 | scaled_delta_exec = grub_reclaim(delta_exec, | |
1284 | rq, | |
1285 | &curr->dl); | |
1286 | } else { | |
1287 | unsigned long scale_freq = arch_scale_freq_capacity(cpu); | |
8ec59c0f | 1288 | unsigned long scale_cpu = arch_scale_cpu_capacity(cpu); |
07881166 JL |
1289 | |
1290 | scaled_delta_exec = cap_scale(delta_exec, scale_freq); | |
1291 | scaled_delta_exec = cap_scale(scaled_delta_exec, scale_cpu); | |
1292 | } | |
1293 | ||
1294 | dl_se->runtime -= scaled_delta_exec; | |
48be3a67 PZ |
1295 | |
1296 | throttle: | |
1297 | if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) { | |
1019a359 | 1298 | dl_se->dl_throttled = 1; |
34be3930 JL |
1299 | |
1300 | /* If requested, inform the user about runtime overruns. */ | |
1301 | if (dl_runtime_exceeded(dl_se) && | |
1302 | (dl_se->flags & SCHED_FLAG_DL_OVERRUN)) | |
1303 | dl_se->dl_overrun = 1; | |
1304 | ||
aab03e05 | 1305 | __dequeue_task_dl(rq, curr, 0); |
a649f237 | 1306 | if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr))) |
aab03e05 DF |
1307 | enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH); |
1308 | ||
1309 | if (!is_leftmost(curr, &rq->dl)) | |
8875125e | 1310 | resched_curr(rq); |
aab03e05 | 1311 | } |
1724813d PZ |
1312 | |
1313 | /* | |
1314 | * Because -- for now -- we share the rt bandwidth, we need to | |
1315 | * account our runtime there too, otherwise actual rt tasks | |
1316 | * would be able to exceed the shared quota. | |
1317 | * | |
1318 | * Account to the root rt group for now. | |
1319 | * | |
1320 | * The solution we're working towards is having the RT groups scheduled | |
1321 | * using deadline servers -- however there's a few nasties to figure | |
1322 | * out before that can happen. | |
1323 | */ | |
1324 | if (rt_bandwidth_enabled()) { | |
1325 | struct rt_rq *rt_rq = &rq->rt; | |
1326 | ||
1327 | raw_spin_lock(&rt_rq->rt_runtime_lock); | |
1724813d PZ |
1328 | /* |
1329 | * We'll let actual RT tasks worry about the overflow here, we | |
faa59937 JL |
1330 | * have our own CBS to keep us inline; only account when RT |
1331 | * bandwidth is relevant. | |
1724813d | 1332 | */ |
faa59937 JL |
1333 | if (sched_rt_bandwidth_account(rt_rq)) |
1334 | rt_rq->rt_time += delta_exec; | |
1724813d PZ |
1335 | raw_spin_unlock(&rt_rq->rt_runtime_lock); |
1336 | } | |
aab03e05 DF |
1337 | } |
1338 | ||
209a0cbd LA |
1339 | static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer) |
1340 | { | |
1341 | struct sched_dl_entity *dl_se = container_of(timer, | |
1342 | struct sched_dl_entity, | |
1343 | inactive_timer); | |
1344 | struct task_struct *p = dl_task_of(dl_se); | |
1345 | struct rq_flags rf; | |
1346 | struct rq *rq; | |
1347 | ||
1348 | rq = task_rq_lock(p, &rf); | |
1349 | ||
ecda2b66 JL |
1350 | sched_clock_tick(); |
1351 | update_rq_clock(rq); | |
1352 | ||
209a0cbd | 1353 | if (!dl_task(p) || p->state == TASK_DEAD) { |
387e3130 LA |
1354 | struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); |
1355 | ||
209a0cbd | 1356 | if (p->state == TASK_DEAD && dl_se->dl_non_contending) { |
794a56eb JL |
1357 | sub_running_bw(&p->dl, dl_rq_of_se(&p->dl)); |
1358 | sub_rq_bw(&p->dl, dl_rq_of_se(&p->dl)); | |
209a0cbd LA |
1359 | dl_se->dl_non_contending = 0; |
1360 | } | |
387e3130 LA |
1361 | |
1362 | raw_spin_lock(&dl_b->lock); | |
8c0944ce | 1363 | __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p))); |
387e3130 | 1364 | raw_spin_unlock(&dl_b->lock); |
209a0cbd LA |
1365 | __dl_clear_params(p); |
1366 | ||
1367 | goto unlock; | |
1368 | } | |
1369 | if (dl_se->dl_non_contending == 0) | |
1370 | goto unlock; | |
1371 | ||
794a56eb | 1372 | sub_running_bw(dl_se, &rq->dl); |
209a0cbd LA |
1373 | dl_se->dl_non_contending = 0; |
1374 | unlock: | |
1375 | task_rq_unlock(rq, p, &rf); | |
1376 | put_task_struct(p); | |
1377 | ||
1378 | return HRTIMER_NORESTART; | |
1379 | } | |
1380 | ||
1381 | void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se) | |
1382 | { | |
1383 | struct hrtimer *timer = &dl_se->inactive_timer; | |
1384 | ||
850377a8 | 1385 | hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); |
209a0cbd LA |
1386 | timer->function = inactive_task_timer; |
1387 | } | |
1388 | ||
1baca4ce JL |
1389 | #ifdef CONFIG_SMP |
1390 | ||
1baca4ce JL |
1391 | static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) |
1392 | { | |
1393 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
1394 | ||
1395 | if (dl_rq->earliest_dl.curr == 0 || | |
1396 | dl_time_before(deadline, dl_rq->earliest_dl.curr)) { | |
b13772f8 PZ |
1397 | if (dl_rq->earliest_dl.curr == 0) |
1398 | cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_HIGHER); | |
1baca4ce | 1399 | dl_rq->earliest_dl.curr = deadline; |
d8206bb3 | 1400 | cpudl_set(&rq->rd->cpudl, rq->cpu, deadline); |
1baca4ce JL |
1401 | } |
1402 | } | |
1403 | ||
1404 | static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) | |
1405 | { | |
1406 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
1407 | ||
1408 | /* | |
1409 | * Since we may have removed our earliest (and/or next earliest) | |
1410 | * task we must recompute them. | |
1411 | */ | |
1412 | if (!dl_rq->dl_nr_running) { | |
1413 | dl_rq->earliest_dl.curr = 0; | |
1414 | dl_rq->earliest_dl.next = 0; | |
d8206bb3 | 1415 | cpudl_clear(&rq->rd->cpudl, rq->cpu); |
b13772f8 | 1416 | cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr); |
1baca4ce | 1417 | } else { |
2161573e | 1418 | struct rb_node *leftmost = dl_rq->root.rb_leftmost; |
1baca4ce JL |
1419 | struct sched_dl_entity *entry; |
1420 | ||
1421 | entry = rb_entry(leftmost, struct sched_dl_entity, rb_node); | |
1422 | dl_rq->earliest_dl.curr = entry->deadline; | |
d8206bb3 | 1423 | cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline); |
1baca4ce JL |
1424 | } |
1425 | } | |
1426 | ||
1427 | #else | |
1428 | ||
1429 | static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {} | |
1430 | static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {} | |
1431 | ||
1432 | #endif /* CONFIG_SMP */ | |
1433 | ||
1434 | static inline | |
1435 | void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
1436 | { | |
1437 | int prio = dl_task_of(dl_se)->prio; | |
1438 | u64 deadline = dl_se->deadline; | |
1439 | ||
1440 | WARN_ON(!dl_prio(prio)); | |
1441 | dl_rq->dl_nr_running++; | |
72465447 | 1442 | add_nr_running(rq_of_dl_rq(dl_rq), 1); |
1baca4ce JL |
1443 | |
1444 | inc_dl_deadline(dl_rq, deadline); | |
1445 | inc_dl_migration(dl_se, dl_rq); | |
1446 | } | |
1447 | ||
1448 | static inline | |
1449 | void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
1450 | { | |
1451 | int prio = dl_task_of(dl_se)->prio; | |
1452 | ||
1453 | WARN_ON(!dl_prio(prio)); | |
1454 | WARN_ON(!dl_rq->dl_nr_running); | |
1455 | dl_rq->dl_nr_running--; | |
72465447 | 1456 | sub_nr_running(rq_of_dl_rq(dl_rq), 1); |
1baca4ce JL |
1457 | |
1458 | dec_dl_deadline(dl_rq, dl_se->deadline); | |
1459 | dec_dl_migration(dl_se, dl_rq); | |
1460 | } | |
1461 | ||
aab03e05 DF |
1462 | static void __enqueue_dl_entity(struct sched_dl_entity *dl_se) |
1463 | { | |
1464 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
2161573e | 1465 | struct rb_node **link = &dl_rq->root.rb_root.rb_node; |
aab03e05 DF |
1466 | struct rb_node *parent = NULL; |
1467 | struct sched_dl_entity *entry; | |
1468 | int leftmost = 1; | |
1469 | ||
1470 | BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node)); | |
1471 | ||
1472 | while (*link) { | |
1473 | parent = *link; | |
1474 | entry = rb_entry(parent, struct sched_dl_entity, rb_node); | |
1475 | if (dl_time_before(dl_se->deadline, entry->deadline)) | |
1476 | link = &parent->rb_left; | |
1477 | else { | |
1478 | link = &parent->rb_right; | |
1479 | leftmost = 0; | |
1480 | } | |
1481 | } | |
1482 | ||
aab03e05 | 1483 | rb_link_node(&dl_se->rb_node, parent, link); |
2161573e | 1484 | rb_insert_color_cached(&dl_se->rb_node, &dl_rq->root, leftmost); |
aab03e05 | 1485 | |
1baca4ce | 1486 | inc_dl_tasks(dl_se, dl_rq); |
aab03e05 DF |
1487 | } |
1488 | ||
1489 | static void __dequeue_dl_entity(struct sched_dl_entity *dl_se) | |
1490 | { | |
1491 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
1492 | ||
1493 | if (RB_EMPTY_NODE(&dl_se->rb_node)) | |
1494 | return; | |
1495 | ||
2161573e | 1496 | rb_erase_cached(&dl_se->rb_node, &dl_rq->root); |
aab03e05 DF |
1497 | RB_CLEAR_NODE(&dl_se->rb_node); |
1498 | ||
1baca4ce | 1499 | dec_dl_tasks(dl_se, dl_rq); |
aab03e05 DF |
1500 | } |
1501 | ||
1502 | static void | |
2d3d891d DF |
1503 | enqueue_dl_entity(struct sched_dl_entity *dl_se, |
1504 | struct sched_dl_entity *pi_se, int flags) | |
aab03e05 DF |
1505 | { |
1506 | BUG_ON(on_dl_rq(dl_se)); | |
1507 | ||
1508 | /* | |
1509 | * If this is a wakeup or a new instance, the scheduling | |
1510 | * parameters of the task might need updating. Otherwise, | |
1511 | * we want a replenishment of its runtime. | |
1512 | */ | |
e36d8677 | 1513 | if (flags & ENQUEUE_WAKEUP) { |
8fd27231 | 1514 | task_contending(dl_se, flags); |
2d3d891d | 1515 | update_dl_entity(dl_se, pi_se); |
e36d8677 | 1516 | } else if (flags & ENQUEUE_REPLENISH) { |
6a503c3b | 1517 | replenish_dl_entity(dl_se, pi_se); |
295d6d5e LA |
1518 | } else if ((flags & ENQUEUE_RESTORE) && |
1519 | dl_time_before(dl_se->deadline, | |
1520 | rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) { | |
1521 | setup_new_dl_entity(dl_se); | |
e36d8677 | 1522 | } |
aab03e05 DF |
1523 | |
1524 | __enqueue_dl_entity(dl_se); | |
1525 | } | |
1526 | ||
1527 | static void dequeue_dl_entity(struct sched_dl_entity *dl_se) | |
1528 | { | |
1529 | __dequeue_dl_entity(dl_se); | |
1530 | } | |
1531 | ||
1532 | static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) | |
1533 | { | |
2d3d891d DF |
1534 | struct task_struct *pi_task = rt_mutex_get_top_task(p); |
1535 | struct sched_dl_entity *pi_se = &p->dl; | |
1536 | ||
1537 | /* | |
193be41e JF |
1538 | * Use the scheduling parameters of the top pi-waiter task if: |
1539 | * - we have a top pi-waiter which is a SCHED_DEADLINE task AND | |
1540 | * - our dl_boosted is set (i.e. the pi-waiter's (absolute) deadline is | |
1541 | * smaller than our deadline OR we are a !SCHED_DEADLINE task getting | |
1542 | * boosted due to a SCHED_DEADLINE pi-waiter). | |
1543 | * Otherwise we keep our runtime and deadline. | |
2d3d891d | 1544 | */ |
193be41e | 1545 | if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) { |
2d3d891d | 1546 | pi_se = &pi_task->dl; |
feff2e65 DBO |
1547 | /* |
1548 | * Because of delays in the detection of the overrun of a | |
1549 | * thread's runtime, it might be the case that a thread | |
1550 | * goes to sleep in a rt mutex with negative runtime. As | |
1551 | * a consequence, the thread will be throttled. | |
1552 | * | |
1553 | * While waiting for the mutex, this thread can also be | |
1554 | * boosted via PI, resulting in a thread that is throttled | |
1555 | * and boosted at the same time. | |
1556 | * | |
1557 | * In this case, the boost overrides the throttle. | |
1558 | */ | |
1559 | if (p->dl.dl_throttled) { | |
1560 | /* | |
1561 | * The replenish timer needs to be canceled. No | |
1562 | * problem if it fires concurrently: boosted threads | |
1563 | * are ignored in dl_task_timer(). | |
1564 | */ | |
1565 | hrtimer_try_to_cancel(&p->dl.dl_timer); | |
1566 | p->dl.dl_throttled = 0; | |
1567 | } | |
64be6f1f JL |
1568 | } else if (!dl_prio(p->normal_prio)) { |
1569 | /* | |
46fcc4b0 LS |
1570 | * Special case in which we have a !SCHED_DEADLINE task that is going |
1571 | * to be deboosted, but exceeds its runtime while doing so. No point in | |
1572 | * replenishing it, as it's going to return back to its original | |
1573 | * scheduling class after this. If it has been throttled, we need to | |
1574 | * clear the flag, otherwise the task may wake up as throttled after | |
1575 | * being boosted again with no means to replenish the runtime and clear | |
1576 | * the throttle. | |
64be6f1f | 1577 | */ |
46fcc4b0 | 1578 | p->dl.dl_throttled = 0; |
64be6f1f JL |
1579 | BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH); |
1580 | return; | |
1581 | } | |
2d3d891d | 1582 | |
df8eac8c DBO |
1583 | /* |
1584 | * Check if a constrained deadline task was activated | |
1585 | * after the deadline but before the next period. | |
1586 | * If that is the case, the task will be throttled and | |
1587 | * the replenishment timer will be set to the next period. | |
1588 | */ | |
3effcb42 | 1589 | if (!p->dl.dl_throttled && !dl_is_implicit(&p->dl)) |
df8eac8c DBO |
1590 | dl_check_constrained_dl(&p->dl); |
1591 | ||
8fd27231 | 1592 | if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & ENQUEUE_RESTORE) { |
794a56eb JL |
1593 | add_rq_bw(&p->dl, &rq->dl); |
1594 | add_running_bw(&p->dl, &rq->dl); | |
8fd27231 | 1595 | } |
e36d8677 | 1596 | |
aab03e05 | 1597 | /* |
e36d8677 | 1598 | * If p is throttled, we do not enqueue it. In fact, if it exhausted |
aab03e05 DF |
1599 | * its budget it needs a replenishment and, since it now is on |
1600 | * its rq, the bandwidth timer callback (which clearly has not | |
1601 | * run yet) will take care of this. | |
e36d8677 LA |
1602 | * However, the active utilization does not depend on the fact |
1603 | * that the task is on the runqueue or not (but depends on the | |
1604 | * task's state - in GRUB parlance, "inactive" vs "active contending"). | |
1605 | * In other words, even if a task is throttled its utilization must | |
1606 | * be counted in the active utilization; hence, we need to call | |
1607 | * add_running_bw(). | |
aab03e05 | 1608 | */ |
e36d8677 | 1609 | if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH)) { |
209a0cbd | 1610 | if (flags & ENQUEUE_WAKEUP) |
8fd27231 | 1611 | task_contending(&p->dl, flags); |
209a0cbd | 1612 | |
aab03e05 | 1613 | return; |
e36d8677 | 1614 | } |
aab03e05 | 1615 | |
2d3d891d | 1616 | enqueue_dl_entity(&p->dl, pi_se, flags); |
1baca4ce | 1617 | |
4b53a341 | 1618 | if (!task_current(rq, p) && p->nr_cpus_allowed > 1) |
1baca4ce | 1619 | enqueue_pushable_dl_task(rq, p); |
aab03e05 DF |
1620 | } |
1621 | ||
1622 | static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) | |
1623 | { | |
1624 | dequeue_dl_entity(&p->dl); | |
1baca4ce | 1625 | dequeue_pushable_dl_task(rq, p); |
aab03e05 DF |
1626 | } |
1627 | ||
1628 | static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) | |
1629 | { | |
1630 | update_curr_dl(rq); | |
1631 | __dequeue_task_dl(rq, p, flags); | |
e36d8677 | 1632 | |
8fd27231 | 1633 | if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & DEQUEUE_SAVE) { |
794a56eb JL |
1634 | sub_running_bw(&p->dl, &rq->dl); |
1635 | sub_rq_bw(&p->dl, &rq->dl); | |
8fd27231 | 1636 | } |
e36d8677 LA |
1637 | |
1638 | /* | |
209a0cbd LA |
1639 | * This check allows to start the inactive timer (or to immediately |
1640 | * decrease the active utilization, if needed) in two cases: | |
e36d8677 LA |
1641 | * when the task blocks and when it is terminating |
1642 | * (p->state == TASK_DEAD). We can handle the two cases in the same | |
1643 | * way, because from GRUB's point of view the same thing is happening | |
1644 | * (the task moves from "active contending" to "active non contending" | |
1645 | * or "inactive") | |
1646 | */ | |
1647 | if (flags & DEQUEUE_SLEEP) | |
209a0cbd | 1648 | task_non_contending(p); |
aab03e05 DF |
1649 | } |
1650 | ||
1651 | /* | |
1652 | * Yield task semantic for -deadline tasks is: | |
1653 | * | |
1654 | * get off from the CPU until our next instance, with | |
1655 | * a new runtime. This is of little use now, since we | |
1656 | * don't have a bandwidth reclaiming mechanism. Anyway, | |
1657 | * bandwidth reclaiming is planned for the future, and | |
1658 | * yield_task_dl will indicate that some spare budget | |
1659 | * is available for other task instances to use it. | |
1660 | */ | |
1661 | static void yield_task_dl(struct rq *rq) | |
1662 | { | |
aab03e05 DF |
1663 | /* |
1664 | * We make the task go to sleep until its current deadline by | |
1665 | * forcing its runtime to zero. This way, update_curr_dl() stops | |
1666 | * it and the bandwidth timer will wake it up and will give it | |
5bfd126e | 1667 | * new scheduling parameters (thanks to dl_yielded=1). |
aab03e05 | 1668 | */ |
48be3a67 PZ |
1669 | rq->curr->dl.dl_yielded = 1; |
1670 | ||
6f1607f1 | 1671 | update_rq_clock(rq); |
aab03e05 | 1672 | update_curr_dl(rq); |
44fb085b WL |
1673 | /* |
1674 | * Tell update_rq_clock() that we've just updated, | |
1675 | * so we don't do microscopic update in schedule() | |
1676 | * and double the fastpath cost. | |
1677 | */ | |
adcc8da8 | 1678 | rq_clock_skip_update(rq); |
aab03e05 DF |
1679 | } |
1680 | ||
1baca4ce JL |
1681 | #ifdef CONFIG_SMP |
1682 | ||
1683 | static int find_later_rq(struct task_struct *task); | |
1baca4ce JL |
1684 | |
1685 | static int | |
1686 | select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) | |
1687 | { | |
1688 | struct task_struct *curr; | |
b4118988 | 1689 | bool select_rq; |
1baca4ce JL |
1690 | struct rq *rq; |
1691 | ||
1d7e974c | 1692 | if (sd_flag != SD_BALANCE_WAKE) |
1baca4ce JL |
1693 | goto out; |
1694 | ||
1695 | rq = cpu_rq(cpu); | |
1696 | ||
1697 | rcu_read_lock(); | |
316c1608 | 1698 | curr = READ_ONCE(rq->curr); /* unlocked access */ |
1baca4ce JL |
1699 | |
1700 | /* | |
1701 | * If we are dealing with a -deadline task, we must | |
1702 | * decide where to wake it up. | |
1703 | * If it has a later deadline and the current task | |
1704 | * on this rq can't move (provided the waking task | |
1705 | * can!) we prefer to send it somewhere else. On the | |
1706 | * other hand, if it has a shorter deadline, we | |
1707 | * try to make it stay here, it might be important. | |
1708 | */ | |
b4118988 LA |
1709 | select_rq = unlikely(dl_task(curr)) && |
1710 | (curr->nr_cpus_allowed < 2 || | |
1711 | !dl_entity_preempt(&p->dl, &curr->dl)) && | |
1712 | p->nr_cpus_allowed > 1; | |
1713 | ||
1714 | /* | |
1715 | * Take the capacity of the CPU into account to | |
1716 | * ensure it fits the requirement of the task. | |
1717 | */ | |
1718 | if (static_branch_unlikely(&sched_asym_cpucapacity)) | |
1719 | select_rq |= !dl_task_fits_capacity(p, cpu); | |
1720 | ||
1721 | if (select_rq) { | |
1baca4ce JL |
1722 | int target = find_later_rq(p); |
1723 | ||
9d514262 | 1724 | if (target != -1 && |
5aa50507 LA |
1725 | (dl_time_before(p->dl.deadline, |
1726 | cpu_rq(target)->dl.earliest_dl.curr) || | |
1727 | (cpu_rq(target)->dl.dl_nr_running == 0))) | |
1baca4ce JL |
1728 | cpu = target; |
1729 | } | |
1730 | rcu_read_unlock(); | |
1731 | ||
1732 | out: | |
1733 | return cpu; | |
1734 | } | |
1735 | ||
1327237a | 1736 | static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused) |
209a0cbd LA |
1737 | { |
1738 | struct rq *rq; | |
1739 | ||
8fd27231 | 1740 | if (p->state != TASK_WAKING) |
209a0cbd LA |
1741 | return; |
1742 | ||
1743 | rq = task_rq(p); | |
1744 | /* | |
1745 | * Since p->state == TASK_WAKING, set_task_cpu() has been called | |
1746 | * from try_to_wake_up(). Hence, p->pi_lock is locked, but | |
1747 | * rq->lock is not... So, lock it | |
1748 | */ | |
1749 | raw_spin_lock(&rq->lock); | |
8fd27231 | 1750 | if (p->dl.dl_non_contending) { |
794a56eb | 1751 | sub_running_bw(&p->dl, &rq->dl); |
8fd27231 LA |
1752 | p->dl.dl_non_contending = 0; |
1753 | /* | |
1754 | * If the timer handler is currently running and the | |
1755 | * timer cannot be cancelled, inactive_task_timer() | |
1756 | * will see that dl_not_contending is not set, and | |
1757 | * will not touch the rq's active utilization, | |
1758 | * so we are still safe. | |
1759 | */ | |
1760 | if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1) | |
1761 | put_task_struct(p); | |
1762 | } | |
794a56eb | 1763 | sub_rq_bw(&p->dl, &rq->dl); |
209a0cbd LA |
1764 | raw_spin_unlock(&rq->lock); |
1765 | } | |
1766 | ||
1baca4ce JL |
1767 | static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p) |
1768 | { | |
1769 | /* | |
1770 | * Current can't be migrated, useless to reschedule, | |
1771 | * let's hope p can move out. | |
1772 | */ | |
4b53a341 | 1773 | if (rq->curr->nr_cpus_allowed == 1 || |
3261ed0b | 1774 | !cpudl_find(&rq->rd->cpudl, rq->curr, NULL)) |
1baca4ce JL |
1775 | return; |
1776 | ||
1777 | /* | |
1778 | * p is migratable, so let's not schedule it and | |
1779 | * see if it is pushed or pulled somewhere else. | |
1780 | */ | |
4b53a341 | 1781 | if (p->nr_cpus_allowed != 1 && |
3261ed0b | 1782 | cpudl_find(&rq->rd->cpudl, p, NULL)) |
1baca4ce JL |
1783 | return; |
1784 | ||
8875125e | 1785 | resched_curr(rq); |
1baca4ce JL |
1786 | } |
1787 | ||
6e2df058 PZ |
1788 | static int balance_dl(struct rq *rq, struct task_struct *p, struct rq_flags *rf) |
1789 | { | |
1790 | if (!on_dl_rq(&p->dl) && need_pull_dl_task(rq, p)) { | |
1791 | /* | |
1792 | * This is OK, because current is on_cpu, which avoids it being | |
1793 | * picked for load-balance and preemption/IRQs are still | |
1794 | * disabled avoiding further scheduler activity on it and we've | |
1795 | * not yet started the picking loop. | |
1796 | */ | |
1797 | rq_unpin_lock(rq, rf); | |
1798 | pull_dl_task(rq); | |
1799 | rq_repin_lock(rq, rf); | |
1800 | } | |
1801 | ||
1802 | return sched_stop_runnable(rq) || sched_dl_runnable(rq); | |
1803 | } | |
1baca4ce JL |
1804 | #endif /* CONFIG_SMP */ |
1805 | ||
aab03e05 DF |
1806 | /* |
1807 | * Only called when both the current and waking task are -deadline | |
1808 | * tasks. | |
1809 | */ | |
1810 | static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, | |
1811 | int flags) | |
1812 | { | |
1baca4ce | 1813 | if (dl_entity_preempt(&p->dl, &rq->curr->dl)) { |
8875125e | 1814 | resched_curr(rq); |
1baca4ce JL |
1815 | return; |
1816 | } | |
1817 | ||
1818 | #ifdef CONFIG_SMP | |
1819 | /* | |
1820 | * In the unlikely case current and p have the same deadline | |
1821 | * let us try to decide what's the best thing to do... | |
1822 | */ | |
332ac17e DF |
1823 | if ((p->dl.deadline == rq->curr->dl.deadline) && |
1824 | !test_tsk_need_resched(rq->curr)) | |
1baca4ce JL |
1825 | check_preempt_equal_dl(rq, p); |
1826 | #endif /* CONFIG_SMP */ | |
aab03e05 DF |
1827 | } |
1828 | ||
1829 | #ifdef CONFIG_SCHED_HRTICK | |
1830 | static void start_hrtick_dl(struct rq *rq, struct task_struct *p) | |
1831 | { | |
177ef2a6 | 1832 | hrtick_start(rq, p->dl.runtime); |
aab03e05 | 1833 | } |
36ce9881 WL |
1834 | #else /* !CONFIG_SCHED_HRTICK */ |
1835 | static void start_hrtick_dl(struct rq *rq, struct task_struct *p) | |
1836 | { | |
1837 | } | |
aab03e05 DF |
1838 | #endif |
1839 | ||
a0e813f2 | 1840 | static void set_next_task_dl(struct rq *rq, struct task_struct *p, bool first) |
ff1cdc94 MS |
1841 | { |
1842 | p->se.exec_start = rq_clock_task(rq); | |
1843 | ||
1844 | /* You can't push away the running task */ | |
1845 | dequeue_pushable_dl_task(rq, p); | |
f95d4eae | 1846 | |
a0e813f2 PZ |
1847 | if (!first) |
1848 | return; | |
1849 | ||
f95d4eae PZ |
1850 | if (hrtick_enabled(rq)) |
1851 | start_hrtick_dl(rq, p); | |
1852 | ||
1853 | if (rq->curr->sched_class != &dl_sched_class) | |
1854 | update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0); | |
1855 | ||
1856 | deadline_queue_push_tasks(rq); | |
ff1cdc94 MS |
1857 | } |
1858 | ||
aab03e05 DF |
1859 | static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq, |
1860 | struct dl_rq *dl_rq) | |
1861 | { | |
2161573e | 1862 | struct rb_node *left = rb_first_cached(&dl_rq->root); |
aab03e05 DF |
1863 | |
1864 | if (!left) | |
1865 | return NULL; | |
1866 | ||
1867 | return rb_entry(left, struct sched_dl_entity, rb_node); | |
1868 | } | |
1869 | ||
98c2f700 | 1870 | static struct task_struct *pick_next_task_dl(struct rq *rq) |
aab03e05 DF |
1871 | { |
1872 | struct sched_dl_entity *dl_se; | |
6e2df058 | 1873 | struct dl_rq *dl_rq = &rq->dl; |
aab03e05 | 1874 | struct task_struct *p; |
aab03e05 | 1875 | |
6e2df058 | 1876 | if (!sched_dl_runnable(rq)) |
aab03e05 DF |
1877 | return NULL; |
1878 | ||
1879 | dl_se = pick_next_dl_entity(rq, dl_rq); | |
1880 | BUG_ON(!dl_se); | |
aab03e05 | 1881 | p = dl_task_of(dl_se); |
a0e813f2 | 1882 | set_next_task_dl(rq, p, true); |
aab03e05 DF |
1883 | return p; |
1884 | } | |
1885 | ||
6e2df058 | 1886 | static void put_prev_task_dl(struct rq *rq, struct task_struct *p) |
aab03e05 DF |
1887 | { |
1888 | update_curr_dl(rq); | |
1baca4ce | 1889 | |
23127296 | 1890 | update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1); |
4b53a341 | 1891 | if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1) |
1baca4ce | 1892 | enqueue_pushable_dl_task(rq, p); |
aab03e05 DF |
1893 | } |
1894 | ||
d84b3131 FW |
1895 | /* |
1896 | * scheduler tick hitting a task of our scheduling class. | |
1897 | * | |
1898 | * NOTE: This function can be called remotely by the tick offload that | |
1899 | * goes along full dynticks. Therefore no local assumption can be made | |
1900 | * and everything must be accessed through the @rq and @curr passed in | |
1901 | * parameters. | |
1902 | */ | |
aab03e05 DF |
1903 | static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued) |
1904 | { | |
1905 | update_curr_dl(rq); | |
1906 | ||
23127296 | 1907 | update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1); |
a7bebf48 WL |
1908 | /* |
1909 | * Even when we have runtime, update_curr_dl() might have resulted in us | |
1910 | * not being the leftmost task anymore. In that case NEED_RESCHED will | |
1911 | * be set and schedule() will start a new hrtick for the next task. | |
1912 | */ | |
1913 | if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 && | |
1914 | is_leftmost(p, &rq->dl)) | |
aab03e05 | 1915 | start_hrtick_dl(rq, p); |
aab03e05 DF |
1916 | } |
1917 | ||
1918 | static void task_fork_dl(struct task_struct *p) | |
1919 | { | |
1920 | /* | |
1921 | * SCHED_DEADLINE tasks cannot fork and this is achieved through | |
1922 | * sched_fork() | |
1923 | */ | |
1924 | } | |
1925 | ||
1baca4ce JL |
1926 | #ifdef CONFIG_SMP |
1927 | ||
1928 | /* Only try algorithms three times */ | |
1929 | #define DL_MAX_TRIES 3 | |
1930 | ||
1931 | static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu) | |
1932 | { | |
1933 | if (!task_running(rq, p) && | |
3bd37062 | 1934 | cpumask_test_cpu(cpu, p->cpus_ptr)) |
1baca4ce | 1935 | return 1; |
1baca4ce JL |
1936 | return 0; |
1937 | } | |
1938 | ||
8b5e770e WL |
1939 | /* |
1940 | * Return the earliest pushable rq's task, which is suitable to be executed | |
1941 | * on the CPU, NULL otherwise: | |
1942 | */ | |
1943 | static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu) | |
1944 | { | |
2161573e | 1945 | struct rb_node *next_node = rq->dl.pushable_dl_tasks_root.rb_leftmost; |
8b5e770e WL |
1946 | struct task_struct *p = NULL; |
1947 | ||
1948 | if (!has_pushable_dl_tasks(rq)) | |
1949 | return NULL; | |
1950 | ||
1951 | next_node: | |
1952 | if (next_node) { | |
1953 | p = rb_entry(next_node, struct task_struct, pushable_dl_tasks); | |
1954 | ||
1955 | if (pick_dl_task(rq, p, cpu)) | |
1956 | return p; | |
1957 | ||
1958 | next_node = rb_next(next_node); | |
1959 | goto next_node; | |
1960 | } | |
1961 | ||
1962 | return NULL; | |
1963 | } | |
1964 | ||
1baca4ce JL |
1965 | static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl); |
1966 | ||
1967 | static int find_later_rq(struct task_struct *task) | |
1968 | { | |
1969 | struct sched_domain *sd; | |
4ba29684 | 1970 | struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl); |
1baca4ce | 1971 | int this_cpu = smp_processor_id(); |
b18c3ca1 | 1972 | int cpu = task_cpu(task); |
1baca4ce JL |
1973 | |
1974 | /* Make sure the mask is initialized first */ | |
1975 | if (unlikely(!later_mask)) | |
1976 | return -1; | |
1977 | ||
4b53a341 | 1978 | if (task->nr_cpus_allowed == 1) |
1baca4ce JL |
1979 | return -1; |
1980 | ||
91ec6778 JL |
1981 | /* |
1982 | * We have to consider system topology and task affinity | |
97fb7a0a | 1983 | * first, then we can look for a suitable CPU. |
91ec6778 | 1984 | */ |
3261ed0b | 1985 | if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask)) |
1baca4ce JL |
1986 | return -1; |
1987 | ||
1988 | /* | |
b18c3ca1 BP |
1989 | * If we are here, some targets have been found, including |
1990 | * the most suitable which is, among the runqueues where the | |
1991 | * current tasks have later deadlines than the task's one, the | |
1992 | * rq with the latest possible one. | |
1baca4ce JL |
1993 | * |
1994 | * Now we check how well this matches with task's | |
1995 | * affinity and system topology. | |
1996 | * | |
97fb7a0a | 1997 | * The last CPU where the task run is our first |
1baca4ce JL |
1998 | * guess, since it is most likely cache-hot there. |
1999 | */ | |
2000 | if (cpumask_test_cpu(cpu, later_mask)) | |
2001 | return cpu; | |
2002 | /* | |
2003 | * Check if this_cpu is to be skipped (i.e., it is | |
2004 | * not in the mask) or not. | |
2005 | */ | |
2006 | if (!cpumask_test_cpu(this_cpu, later_mask)) | |
2007 | this_cpu = -1; | |
2008 | ||
2009 | rcu_read_lock(); | |
2010 | for_each_domain(cpu, sd) { | |
2011 | if (sd->flags & SD_WAKE_AFFINE) { | |
b18c3ca1 | 2012 | int best_cpu; |
1baca4ce JL |
2013 | |
2014 | /* | |
2015 | * If possible, preempting this_cpu is | |
2016 | * cheaper than migrating. | |
2017 | */ | |
2018 | if (this_cpu != -1 && | |
2019 | cpumask_test_cpu(this_cpu, sched_domain_span(sd))) { | |
2020 | rcu_read_unlock(); | |
2021 | return this_cpu; | |
2022 | } | |
2023 | ||
b18c3ca1 BP |
2024 | best_cpu = cpumask_first_and(later_mask, |
2025 | sched_domain_span(sd)); | |
1baca4ce | 2026 | /* |
97fb7a0a | 2027 | * Last chance: if a CPU being in both later_mask |
b18c3ca1 | 2028 | * and current sd span is valid, that becomes our |
97fb7a0a | 2029 | * choice. Of course, the latest possible CPU is |
b18c3ca1 | 2030 | * already under consideration through later_mask. |
1baca4ce | 2031 | */ |
b18c3ca1 | 2032 | if (best_cpu < nr_cpu_ids) { |
1baca4ce JL |
2033 | rcu_read_unlock(); |
2034 | return best_cpu; | |
2035 | } | |
2036 | } | |
2037 | } | |
2038 | rcu_read_unlock(); | |
2039 | ||
2040 | /* | |
2041 | * At this point, all our guesses failed, we just return | |
2042 | * 'something', and let the caller sort the things out. | |
2043 | */ | |
2044 | if (this_cpu != -1) | |
2045 | return this_cpu; | |
2046 | ||
2047 | cpu = cpumask_any(later_mask); | |
2048 | if (cpu < nr_cpu_ids) | |
2049 | return cpu; | |
2050 | ||
2051 | return -1; | |
2052 | } | |
2053 | ||
2054 | /* Locks the rq it finds */ | |
2055 | static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq) | |
2056 | { | |
2057 | struct rq *later_rq = NULL; | |
2058 | int tries; | |
2059 | int cpu; | |
2060 | ||
2061 | for (tries = 0; tries < DL_MAX_TRIES; tries++) { | |
2062 | cpu = find_later_rq(task); | |
2063 | ||
2064 | if ((cpu == -1) || (cpu == rq->cpu)) | |
2065 | break; | |
2066 | ||
2067 | later_rq = cpu_rq(cpu); | |
2068 | ||
5aa50507 LA |
2069 | if (later_rq->dl.dl_nr_running && |
2070 | !dl_time_before(task->dl.deadline, | |
9d514262 WL |
2071 | later_rq->dl.earliest_dl.curr)) { |
2072 | /* | |
2073 | * Target rq has tasks of equal or earlier deadline, | |
2074 | * retrying does not release any lock and is unlikely | |
2075 | * to yield a different result. | |
2076 | */ | |
2077 | later_rq = NULL; | |
2078 | break; | |
2079 | } | |
2080 | ||
1baca4ce JL |
2081 | /* Retry if something changed. */ |
2082 | if (double_lock_balance(rq, later_rq)) { | |
2083 | if (unlikely(task_rq(task) != rq || | |
3bd37062 | 2084 | !cpumask_test_cpu(later_rq->cpu, task->cpus_ptr) || |
da0c1e65 | 2085 | task_running(rq, task) || |
13b5ab02 | 2086 | !dl_task(task) || |
da0c1e65 | 2087 | !task_on_rq_queued(task))) { |
1baca4ce JL |
2088 | double_unlock_balance(rq, later_rq); |
2089 | later_rq = NULL; | |
2090 | break; | |
2091 | } | |
2092 | } | |
2093 | ||
2094 | /* | |
2095 | * If the rq we found has no -deadline task, or | |
2096 | * its earliest one has a later deadline than our | |
2097 | * task, the rq is a good one. | |
2098 | */ | |
2099 | if (!later_rq->dl.dl_nr_running || | |
2100 | dl_time_before(task->dl.deadline, | |
2101 | later_rq->dl.earliest_dl.curr)) | |
2102 | break; | |
2103 | ||
2104 | /* Otherwise we try again. */ | |
2105 | double_unlock_balance(rq, later_rq); | |
2106 | later_rq = NULL; | |
2107 | } | |
2108 | ||
2109 | return later_rq; | |
2110 | } | |
2111 | ||
2112 | static struct task_struct *pick_next_pushable_dl_task(struct rq *rq) | |
2113 | { | |
2114 | struct task_struct *p; | |
2115 | ||
2116 | if (!has_pushable_dl_tasks(rq)) | |
2117 | return NULL; | |
2118 | ||
2161573e | 2119 | p = rb_entry(rq->dl.pushable_dl_tasks_root.rb_leftmost, |
1baca4ce JL |
2120 | struct task_struct, pushable_dl_tasks); |
2121 | ||
2122 | BUG_ON(rq->cpu != task_cpu(p)); | |
2123 | BUG_ON(task_current(rq, p)); | |
4b53a341 | 2124 | BUG_ON(p->nr_cpus_allowed <= 1); |
1baca4ce | 2125 | |
da0c1e65 | 2126 | BUG_ON(!task_on_rq_queued(p)); |
1baca4ce JL |
2127 | BUG_ON(!dl_task(p)); |
2128 | ||
2129 | return p; | |
2130 | } | |
2131 | ||
2132 | /* | |
2133 | * See if the non running -deadline tasks on this rq | |
2134 | * can be sent to some other CPU where they can preempt | |
2135 | * and start executing. | |
2136 | */ | |
2137 | static int push_dl_task(struct rq *rq) | |
2138 | { | |
2139 | struct task_struct *next_task; | |
2140 | struct rq *later_rq; | |
c51b8ab5 | 2141 | int ret = 0; |
1baca4ce JL |
2142 | |
2143 | if (!rq->dl.overloaded) | |
2144 | return 0; | |
2145 | ||
2146 | next_task = pick_next_pushable_dl_task(rq); | |
2147 | if (!next_task) | |
2148 | return 0; | |
2149 | ||
2150 | retry: | |
9ebc6053 | 2151 | if (WARN_ON(next_task == rq->curr)) |
1baca4ce | 2152 | return 0; |
1baca4ce JL |
2153 | |
2154 | /* | |
2155 | * If next_task preempts rq->curr, and rq->curr | |
2156 | * can move away, it makes sense to just reschedule | |
2157 | * without going further in pushing next_task. | |
2158 | */ | |
2159 | if (dl_task(rq->curr) && | |
2160 | dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) && | |
4b53a341 | 2161 | rq->curr->nr_cpus_allowed > 1) { |
8875125e | 2162 | resched_curr(rq); |
1baca4ce JL |
2163 | return 0; |
2164 | } | |
2165 | ||
2166 | /* We might release rq lock */ | |
2167 | get_task_struct(next_task); | |
2168 | ||
2169 | /* Will lock the rq it'll find */ | |
2170 | later_rq = find_lock_later_rq(next_task, rq); | |
2171 | if (!later_rq) { | |
2172 | struct task_struct *task; | |
2173 | ||
2174 | /* | |
2175 | * We must check all this again, since | |
2176 | * find_lock_later_rq releases rq->lock and it is | |
2177 | * then possible that next_task has migrated. | |
2178 | */ | |
2179 | task = pick_next_pushable_dl_task(rq); | |
a776b968 | 2180 | if (task == next_task) { |
1baca4ce JL |
2181 | /* |
2182 | * The task is still there. We don't try | |
97fb7a0a | 2183 | * again, some other CPU will pull it when ready. |
1baca4ce | 2184 | */ |
1baca4ce JL |
2185 | goto out; |
2186 | } | |
2187 | ||
2188 | if (!task) | |
2189 | /* No more tasks */ | |
2190 | goto out; | |
2191 | ||
2192 | put_task_struct(next_task); | |
2193 | next_task = task; | |
2194 | goto retry; | |
2195 | } | |
2196 | ||
2197 | deactivate_task(rq, next_task, 0); | |
2198 | set_task_cpu(next_task, later_rq->cpu); | |
840d7196 DBO |
2199 | |
2200 | /* | |
2201 | * Update the later_rq clock here, because the clock is used | |
2202 | * by the cpufreq_update_util() inside __add_running_bw(). | |
2203 | */ | |
2204 | update_rq_clock(later_rq); | |
840d7196 | 2205 | activate_task(later_rq, next_task, ENQUEUE_NOCLOCK); |
c51b8ab5 | 2206 | ret = 1; |
1baca4ce | 2207 | |
8875125e | 2208 | resched_curr(later_rq); |
1baca4ce JL |
2209 | |
2210 | double_unlock_balance(rq, later_rq); | |
2211 | ||
2212 | out: | |
2213 | put_task_struct(next_task); | |
2214 | ||
c51b8ab5 | 2215 | return ret; |
1baca4ce JL |
2216 | } |
2217 | ||
2218 | static void push_dl_tasks(struct rq *rq) | |
2219 | { | |
4ffa08ed | 2220 | /* push_dl_task() will return true if it moved a -deadline task */ |
1baca4ce JL |
2221 | while (push_dl_task(rq)) |
2222 | ; | |
aab03e05 DF |
2223 | } |
2224 | ||
0ea60c20 | 2225 | static void pull_dl_task(struct rq *this_rq) |
1baca4ce | 2226 | { |
0ea60c20 | 2227 | int this_cpu = this_rq->cpu, cpu; |
1baca4ce | 2228 | struct task_struct *p; |
0ea60c20 | 2229 | bool resched = false; |
1baca4ce JL |
2230 | struct rq *src_rq; |
2231 | u64 dmin = LONG_MAX; | |
2232 | ||
2233 | if (likely(!dl_overloaded(this_rq))) | |
0ea60c20 | 2234 | return; |
1baca4ce JL |
2235 | |
2236 | /* | |
2237 | * Match the barrier from dl_set_overloaded; this guarantees that if we | |
2238 | * see overloaded we must also see the dlo_mask bit. | |
2239 | */ | |
2240 | smp_rmb(); | |
2241 | ||
2242 | for_each_cpu(cpu, this_rq->rd->dlo_mask) { | |
2243 | if (this_cpu == cpu) | |
2244 | continue; | |
2245 | ||
2246 | src_rq = cpu_rq(cpu); | |
2247 | ||
2248 | /* | |
2249 | * It looks racy, abd it is! However, as in sched_rt.c, | |
2250 | * we are fine with this. | |
2251 | */ | |
2252 | if (this_rq->dl.dl_nr_running && | |
2253 | dl_time_before(this_rq->dl.earliest_dl.curr, | |
2254 | src_rq->dl.earliest_dl.next)) | |
2255 | continue; | |
2256 | ||
2257 | /* Might drop this_rq->lock */ | |
2258 | double_lock_balance(this_rq, src_rq); | |
2259 | ||
2260 | /* | |
2261 | * If there are no more pullable tasks on the | |
2262 | * rq, we're done with it. | |
2263 | */ | |
2264 | if (src_rq->dl.dl_nr_running <= 1) | |
2265 | goto skip; | |
2266 | ||
8b5e770e | 2267 | p = pick_earliest_pushable_dl_task(src_rq, this_cpu); |
1baca4ce JL |
2268 | |
2269 | /* | |
2270 | * We found a task to be pulled if: | |
2271 | * - it preempts our current (if there's one), | |
2272 | * - it will preempt the last one we pulled (if any). | |
2273 | */ | |
2274 | if (p && dl_time_before(p->dl.deadline, dmin) && | |
2275 | (!this_rq->dl.dl_nr_running || | |
2276 | dl_time_before(p->dl.deadline, | |
2277 | this_rq->dl.earliest_dl.curr))) { | |
2278 | WARN_ON(p == src_rq->curr); | |
da0c1e65 | 2279 | WARN_ON(!task_on_rq_queued(p)); |
1baca4ce JL |
2280 | |
2281 | /* | |
2282 | * Then we pull iff p has actually an earlier | |
2283 | * deadline than the current task of its runqueue. | |
2284 | */ | |
2285 | if (dl_time_before(p->dl.deadline, | |
2286 | src_rq->curr->dl.deadline)) | |
2287 | goto skip; | |
2288 | ||
0ea60c20 | 2289 | resched = true; |
1baca4ce JL |
2290 | |
2291 | deactivate_task(src_rq, p, 0); | |
2292 | set_task_cpu(p, this_cpu); | |
2293 | activate_task(this_rq, p, 0); | |
2294 | dmin = p->dl.deadline; | |
2295 | ||
2296 | /* Is there any other task even earlier? */ | |
2297 | } | |
2298 | skip: | |
2299 | double_unlock_balance(this_rq, src_rq); | |
2300 | } | |
2301 | ||
0ea60c20 PZ |
2302 | if (resched) |
2303 | resched_curr(this_rq); | |
1baca4ce JL |
2304 | } |
2305 | ||
2306 | /* | |
2307 | * Since the task is not running and a reschedule is not going to happen | |
2308 | * anytime soon on its runqueue, we try pushing it away now. | |
2309 | */ | |
2310 | static void task_woken_dl(struct rq *rq, struct task_struct *p) | |
2311 | { | |
2312 | if (!task_running(rq, p) && | |
2313 | !test_tsk_need_resched(rq->curr) && | |
4b53a341 | 2314 | p->nr_cpus_allowed > 1 && |
1baca4ce | 2315 | dl_task(rq->curr) && |
4b53a341 | 2316 | (rq->curr->nr_cpus_allowed < 2 || |
6b0a563f | 2317 | !dl_entity_preempt(&p->dl, &rq->curr->dl))) { |
1baca4ce JL |
2318 | push_dl_tasks(rq); |
2319 | } | |
2320 | } | |
2321 | ||
2322 | static void set_cpus_allowed_dl(struct task_struct *p, | |
2323 | const struct cpumask *new_mask) | |
2324 | { | |
7f51412a | 2325 | struct root_domain *src_rd; |
6c37067e | 2326 | struct rq *rq; |
1baca4ce JL |
2327 | |
2328 | BUG_ON(!dl_task(p)); | |
2329 | ||
7f51412a JL |
2330 | rq = task_rq(p); |
2331 | src_rd = rq->rd; | |
2332 | /* | |
2333 | * Migrating a SCHED_DEADLINE task between exclusive | |
2334 | * cpusets (different root_domains) entails a bandwidth | |
2335 | * update. We already made space for us in the destination | |
2336 | * domain (see cpuset_can_attach()). | |
2337 | */ | |
2338 | if (!cpumask_intersects(src_rd->span, new_mask)) { | |
2339 | struct dl_bw *src_dl_b; | |
2340 | ||
2341 | src_dl_b = dl_bw_of(cpu_of(rq)); | |
2342 | /* | |
2343 | * We now free resources of the root_domain we are migrating | |
2344 | * off. In the worst case, sched_setattr() may temporary fail | |
2345 | * until we complete the update. | |
2346 | */ | |
2347 | raw_spin_lock(&src_dl_b->lock); | |
8c0944ce | 2348 | __dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p))); |
7f51412a JL |
2349 | raw_spin_unlock(&src_dl_b->lock); |
2350 | } | |
2351 | ||
6c37067e | 2352 | set_cpus_allowed_common(p, new_mask); |
1baca4ce JL |
2353 | } |
2354 | ||
2355 | /* Assumes rq->lock is held */ | |
2356 | static void rq_online_dl(struct rq *rq) | |
2357 | { | |
2358 | if (rq->dl.overloaded) | |
2359 | dl_set_overload(rq); | |
6bfd6d72 | 2360 | |
16b26943 | 2361 | cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu); |
6bfd6d72 | 2362 | if (rq->dl.dl_nr_running > 0) |
d8206bb3 | 2363 | cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr); |
1baca4ce JL |
2364 | } |
2365 | ||
2366 | /* Assumes rq->lock is held */ | |
2367 | static void rq_offline_dl(struct rq *rq) | |
2368 | { | |
2369 | if (rq->dl.overloaded) | |
2370 | dl_clear_overload(rq); | |
6bfd6d72 | 2371 | |
d8206bb3 | 2372 | cpudl_clear(&rq->rd->cpudl, rq->cpu); |
16b26943 | 2373 | cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu); |
1baca4ce JL |
2374 | } |
2375 | ||
a6c0e746 | 2376 | void __init init_sched_dl_class(void) |
1baca4ce JL |
2377 | { |
2378 | unsigned int i; | |
2379 | ||
2380 | for_each_possible_cpu(i) | |
2381 | zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i), | |
2382 | GFP_KERNEL, cpu_to_node(i)); | |
2383 | } | |
2384 | ||
f9a25f77 MP |
2385 | void dl_add_task_root_domain(struct task_struct *p) |
2386 | { | |
2387 | struct rq_flags rf; | |
2388 | struct rq *rq; | |
2389 | struct dl_bw *dl_b; | |
2390 | ||
2391 | rq = task_rq_lock(p, &rf); | |
2392 | if (!dl_task(p)) | |
2393 | goto unlock; | |
2394 | ||
2395 | dl_b = &rq->rd->dl_bw; | |
2396 | raw_spin_lock(&dl_b->lock); | |
2397 | ||
2398 | __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span)); | |
2399 | ||
2400 | raw_spin_unlock(&dl_b->lock); | |
2401 | ||
2402 | unlock: | |
2403 | task_rq_unlock(rq, p, &rf); | |
2404 | } | |
2405 | ||
2406 | void dl_clear_root_domain(struct root_domain *rd) | |
2407 | { | |
2408 | unsigned long flags; | |
2409 | ||
2410 | raw_spin_lock_irqsave(&rd->dl_bw.lock, flags); | |
2411 | rd->dl_bw.total_bw = 0; | |
2412 | raw_spin_unlock_irqrestore(&rd->dl_bw.lock, flags); | |
2413 | } | |
2414 | ||
1baca4ce JL |
2415 | #endif /* CONFIG_SMP */ |
2416 | ||
aab03e05 DF |
2417 | static void switched_from_dl(struct rq *rq, struct task_struct *p) |
2418 | { | |
a649f237 | 2419 | /* |
209a0cbd LA |
2420 | * task_non_contending() can start the "inactive timer" (if the 0-lag |
2421 | * time is in the future). If the task switches back to dl before | |
2422 | * the "inactive timer" fires, it can continue to consume its current | |
2423 | * runtime using its current deadline. If it stays outside of | |
2424 | * SCHED_DEADLINE until the 0-lag time passes, inactive_task_timer() | |
2425 | * will reset the task parameters. | |
a649f237 | 2426 | */ |
209a0cbd LA |
2427 | if (task_on_rq_queued(p) && p->dl.dl_runtime) |
2428 | task_non_contending(p); | |
2429 | ||
e117cb52 JL |
2430 | if (!task_on_rq_queued(p)) { |
2431 | /* | |
2432 | * Inactive timer is armed. However, p is leaving DEADLINE and | |
2433 | * might migrate away from this rq while continuing to run on | |
2434 | * some other class. We need to remove its contribution from | |
2435 | * this rq running_bw now, or sub_rq_bw (below) will complain. | |
2436 | */ | |
2437 | if (p->dl.dl_non_contending) | |
2438 | sub_running_bw(&p->dl, &rq->dl); | |
794a56eb | 2439 | sub_rq_bw(&p->dl, &rq->dl); |
e117cb52 | 2440 | } |
8fd27231 | 2441 | |
209a0cbd LA |
2442 | /* |
2443 | * We cannot use inactive_task_timer() to invoke sub_running_bw() | |
2444 | * at the 0-lag time, because the task could have been migrated | |
2445 | * while SCHED_OTHER in the meanwhile. | |
2446 | */ | |
2447 | if (p->dl.dl_non_contending) | |
2448 | p->dl.dl_non_contending = 0; | |
a5e7be3b | 2449 | |
1baca4ce JL |
2450 | /* |
2451 | * Since this might be the only -deadline task on the rq, | |
2452 | * this is the right place to try to pull some other one | |
97fb7a0a | 2453 | * from an overloaded CPU, if any. |
1baca4ce | 2454 | */ |
cd660911 WL |
2455 | if (!task_on_rq_queued(p) || rq->dl.dl_nr_running) |
2456 | return; | |
2457 | ||
02d8ec94 | 2458 | deadline_queue_pull_task(rq); |
aab03e05 DF |
2459 | } |
2460 | ||
1baca4ce JL |
2461 | /* |
2462 | * When switching to -deadline, we may overload the rq, then | |
2463 | * we try to push someone off, if possible. | |
2464 | */ | |
aab03e05 DF |
2465 | static void switched_to_dl(struct rq *rq, struct task_struct *p) |
2466 | { | |
209a0cbd LA |
2467 | if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1) |
2468 | put_task_struct(p); | |
98b0a857 JL |
2469 | |
2470 | /* If p is not queued we will update its parameters at next wakeup. */ | |
8fd27231 | 2471 | if (!task_on_rq_queued(p)) { |
794a56eb | 2472 | add_rq_bw(&p->dl, &rq->dl); |
98b0a857 | 2473 | |
8fd27231 LA |
2474 | return; |
2475 | } | |
72f9f3fd | 2476 | |
98b0a857 | 2477 | if (rq->curr != p) { |
1baca4ce | 2478 | #ifdef CONFIG_SMP |
4b53a341 | 2479 | if (p->nr_cpus_allowed > 1 && rq->dl.overloaded) |
02d8ec94 | 2480 | deadline_queue_push_tasks(rq); |
619bd4a7 | 2481 | #endif |
9916e214 PZ |
2482 | if (dl_task(rq->curr)) |
2483 | check_preempt_curr_dl(rq, p, 0); | |
2484 | else | |
2485 | resched_curr(rq); | |
aab03e05 DF |
2486 | } |
2487 | } | |
2488 | ||
1baca4ce JL |
2489 | /* |
2490 | * If the scheduling parameters of a -deadline task changed, | |
2491 | * a push or pull operation might be needed. | |
2492 | */ | |
aab03e05 DF |
2493 | static void prio_changed_dl(struct rq *rq, struct task_struct *p, |
2494 | int oldprio) | |
2495 | { | |
da0c1e65 | 2496 | if (task_on_rq_queued(p) || rq->curr == p) { |
aab03e05 | 2497 | #ifdef CONFIG_SMP |
1baca4ce JL |
2498 | /* |
2499 | * This might be too much, but unfortunately | |
2500 | * we don't have the old deadline value, and | |
2501 | * we can't argue if the task is increasing | |
2502 | * or lowering its prio, so... | |
2503 | */ | |
2504 | if (!rq->dl.overloaded) | |
02d8ec94 | 2505 | deadline_queue_pull_task(rq); |
1baca4ce JL |
2506 | |
2507 | /* | |
2508 | * If we now have a earlier deadline task than p, | |
2509 | * then reschedule, provided p is still on this | |
2510 | * runqueue. | |
2511 | */ | |
9916e214 | 2512 | if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline)) |
8875125e | 2513 | resched_curr(rq); |
1baca4ce JL |
2514 | #else |
2515 | /* | |
2516 | * Again, we don't know if p has a earlier | |
2517 | * or later deadline, so let's blindly set a | |
2518 | * (maybe not needed) rescheduling point. | |
2519 | */ | |
8875125e | 2520 | resched_curr(rq); |
1baca4ce | 2521 | #endif /* CONFIG_SMP */ |
801ccdbf | 2522 | } |
aab03e05 | 2523 | } |
aab03e05 | 2524 | |
590d6979 | 2525 | const struct sched_class dl_sched_class |
33def849 | 2526 | __section("__dl_sched_class") = { |
aab03e05 DF |
2527 | .enqueue_task = enqueue_task_dl, |
2528 | .dequeue_task = dequeue_task_dl, | |
2529 | .yield_task = yield_task_dl, | |
2530 | ||
2531 | .check_preempt_curr = check_preempt_curr_dl, | |
2532 | ||
2533 | .pick_next_task = pick_next_task_dl, | |
2534 | .put_prev_task = put_prev_task_dl, | |
03b7fad1 | 2535 | .set_next_task = set_next_task_dl, |
aab03e05 DF |
2536 | |
2537 | #ifdef CONFIG_SMP | |
6e2df058 | 2538 | .balance = balance_dl, |
aab03e05 | 2539 | .select_task_rq = select_task_rq_dl, |
209a0cbd | 2540 | .migrate_task_rq = migrate_task_rq_dl, |
1baca4ce JL |
2541 | .set_cpus_allowed = set_cpus_allowed_dl, |
2542 | .rq_online = rq_online_dl, | |
2543 | .rq_offline = rq_offline_dl, | |
1baca4ce | 2544 | .task_woken = task_woken_dl, |
aab03e05 DF |
2545 | #endif |
2546 | ||
aab03e05 DF |
2547 | .task_tick = task_tick_dl, |
2548 | .task_fork = task_fork_dl, | |
aab03e05 DF |
2549 | |
2550 | .prio_changed = prio_changed_dl, | |
2551 | .switched_from = switched_from_dl, | |
2552 | .switched_to = switched_to_dl, | |
6e998916 SG |
2553 | |
2554 | .update_curr = update_curr_dl, | |
aab03e05 | 2555 | }; |
acb32132 | 2556 | |
26762423 PL |
2557 | /* Used for dl_bw check and update, used under sched_rt_handler()::mutex */ |
2558 | static u64 dl_generation; | |
2559 | ||
06a76fe0 NP |
2560 | int sched_dl_global_validate(void) |
2561 | { | |
2562 | u64 runtime = global_rt_runtime(); | |
2563 | u64 period = global_rt_period(); | |
2564 | u64 new_bw = to_ratio(period, runtime); | |
26762423 | 2565 | u64 gen = ++dl_generation; |
06a76fe0 | 2566 | struct dl_bw *dl_b; |
a57415f5 | 2567 | int cpu, cpus, ret = 0; |
06a76fe0 NP |
2568 | unsigned long flags; |
2569 | ||
2570 | /* | |
2571 | * Here we want to check the bandwidth not being set to some | |
2572 | * value smaller than the currently allocated bandwidth in | |
2573 | * any of the root_domains. | |
06a76fe0 NP |
2574 | */ |
2575 | for_each_possible_cpu(cpu) { | |
2576 | rcu_read_lock_sched(); | |
26762423 PL |
2577 | |
2578 | if (dl_bw_visited(cpu, gen)) | |
2579 | goto next; | |
2580 | ||
06a76fe0 | 2581 | dl_b = dl_bw_of(cpu); |
a57415f5 | 2582 | cpus = dl_bw_cpus(cpu); |
06a76fe0 NP |
2583 | |
2584 | raw_spin_lock_irqsave(&dl_b->lock, flags); | |
a57415f5 | 2585 | if (new_bw * cpus < dl_b->total_bw) |
06a76fe0 NP |
2586 | ret = -EBUSY; |
2587 | raw_spin_unlock_irqrestore(&dl_b->lock, flags); | |
2588 | ||
26762423 | 2589 | next: |
06a76fe0 NP |
2590 | rcu_read_unlock_sched(); |
2591 | ||
2592 | if (ret) | |
2593 | break; | |
2594 | } | |
2595 | ||
2596 | return ret; | |
2597 | } | |
2598 | ||
ba4f7bc1 | 2599 | static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq) |
06a76fe0 NP |
2600 | { |
2601 | if (global_rt_runtime() == RUNTIME_INF) { | |
2602 | dl_rq->bw_ratio = 1 << RATIO_SHIFT; | |
2603 | dl_rq->extra_bw = 1 << BW_SHIFT; | |
2604 | } else { | |
2605 | dl_rq->bw_ratio = to_ratio(global_rt_runtime(), | |
2606 | global_rt_period()) >> (BW_SHIFT - RATIO_SHIFT); | |
2607 | dl_rq->extra_bw = to_ratio(global_rt_period(), | |
2608 | global_rt_runtime()); | |
2609 | } | |
2610 | } | |
2611 | ||
2612 | void sched_dl_do_global(void) | |
2613 | { | |
2614 | u64 new_bw = -1; | |
26762423 | 2615 | u64 gen = ++dl_generation; |
06a76fe0 NP |
2616 | struct dl_bw *dl_b; |
2617 | int cpu; | |
2618 | unsigned long flags; | |
2619 | ||
2620 | def_dl_bandwidth.dl_period = global_rt_period(); | |
2621 | def_dl_bandwidth.dl_runtime = global_rt_runtime(); | |
2622 | ||
2623 | if (global_rt_runtime() != RUNTIME_INF) | |
2624 | new_bw = to_ratio(global_rt_period(), global_rt_runtime()); | |
2625 | ||
06a76fe0 NP |
2626 | for_each_possible_cpu(cpu) { |
2627 | rcu_read_lock_sched(); | |
26762423 PL |
2628 | |
2629 | if (dl_bw_visited(cpu, gen)) { | |
2630 | rcu_read_unlock_sched(); | |
2631 | continue; | |
2632 | } | |
2633 | ||
06a76fe0 NP |
2634 | dl_b = dl_bw_of(cpu); |
2635 | ||
2636 | raw_spin_lock_irqsave(&dl_b->lock, flags); | |
2637 | dl_b->bw = new_bw; | |
2638 | raw_spin_unlock_irqrestore(&dl_b->lock, flags); | |
2639 | ||
2640 | rcu_read_unlock_sched(); | |
2641 | init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl); | |
2642 | } | |
2643 | } | |
2644 | ||
2645 | /* | |
2646 | * We must be sure that accepting a new task (or allowing changing the | |
2647 | * parameters of an existing one) is consistent with the bandwidth | |
2648 | * constraints. If yes, this function also accordingly updates the currently | |
2649 | * allocated bandwidth to reflect the new situation. | |
2650 | * | |
2651 | * This function is called while holding p's rq->lock. | |
2652 | */ | |
2653 | int sched_dl_overflow(struct task_struct *p, int policy, | |
2654 | const struct sched_attr *attr) | |
2655 | { | |
06a76fe0 NP |
2656 | u64 period = attr->sched_period ?: attr->sched_deadline; |
2657 | u64 runtime = attr->sched_runtime; | |
2658 | u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0; | |
60ffd5ed LA |
2659 | int cpus, err = -1, cpu = task_cpu(p); |
2660 | struct dl_bw *dl_b = dl_bw_of(cpu); | |
2661 | unsigned long cap; | |
06a76fe0 | 2662 | |
794a56eb JL |
2663 | if (attr->sched_flags & SCHED_FLAG_SUGOV) |
2664 | return 0; | |
2665 | ||
06a76fe0 NP |
2666 | /* !deadline task may carry old deadline bandwidth */ |
2667 | if (new_bw == p->dl.dl_bw && task_has_dl_policy(p)) | |
2668 | return 0; | |
2669 | ||
2670 | /* | |
2671 | * Either if a task, enters, leave, or stays -deadline but changes | |
2672 | * its parameters, we may need to update accordingly the total | |
2673 | * allocated bandwidth of the container. | |
2674 | */ | |
2675 | raw_spin_lock(&dl_b->lock); | |
60ffd5ed LA |
2676 | cpus = dl_bw_cpus(cpu); |
2677 | cap = dl_bw_capacity(cpu); | |
2678 | ||
06a76fe0 | 2679 | if (dl_policy(policy) && !task_has_dl_policy(p) && |
60ffd5ed | 2680 | !__dl_overflow(dl_b, cap, 0, new_bw)) { |
06a76fe0 | 2681 | if (hrtimer_active(&p->dl.inactive_timer)) |
8c0944ce | 2682 | __dl_sub(dl_b, p->dl.dl_bw, cpus); |
06a76fe0 NP |
2683 | __dl_add(dl_b, new_bw, cpus); |
2684 | err = 0; | |
2685 | } else if (dl_policy(policy) && task_has_dl_policy(p) && | |
60ffd5ed | 2686 | !__dl_overflow(dl_b, cap, p->dl.dl_bw, new_bw)) { |
06a76fe0 NP |
2687 | /* |
2688 | * XXX this is slightly incorrect: when the task | |
2689 | * utilization decreases, we should delay the total | |
2690 | * utilization change until the task's 0-lag point. | |
2691 | * But this would require to set the task's "inactive | |
2692 | * timer" when the task is not inactive. | |
2693 | */ | |
8c0944ce | 2694 | __dl_sub(dl_b, p->dl.dl_bw, cpus); |
06a76fe0 NP |
2695 | __dl_add(dl_b, new_bw, cpus); |
2696 | dl_change_utilization(p, new_bw); | |
2697 | err = 0; | |
2698 | } else if (!dl_policy(policy) && task_has_dl_policy(p)) { | |
2699 | /* | |
2700 | * Do not decrease the total deadline utilization here, | |
2701 | * switched_from_dl() will take care to do it at the correct | |
2702 | * (0-lag) time. | |
2703 | */ | |
2704 | err = 0; | |
2705 | } | |
2706 | raw_spin_unlock(&dl_b->lock); | |
2707 | ||
2708 | return err; | |
2709 | } | |
2710 | ||
2711 | /* | |
2712 | * This function initializes the sched_dl_entity of a newly becoming | |
2713 | * SCHED_DEADLINE task. | |
2714 | * | |
2715 | * Only the static values are considered here, the actual runtime and the | |
2716 | * absolute deadline will be properly calculated when the task is enqueued | |
2717 | * for the first time with its new policy. | |
2718 | */ | |
2719 | void __setparam_dl(struct task_struct *p, const struct sched_attr *attr) | |
2720 | { | |
2721 | struct sched_dl_entity *dl_se = &p->dl; | |
2722 | ||
2723 | dl_se->dl_runtime = attr->sched_runtime; | |
2724 | dl_se->dl_deadline = attr->sched_deadline; | |
2725 | dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline; | |
2726 | dl_se->flags = attr->sched_flags; | |
2727 | dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime); | |
2728 | dl_se->dl_density = to_ratio(dl_se->dl_deadline, dl_se->dl_runtime); | |
2729 | } | |
2730 | ||
2731 | void __getparam_dl(struct task_struct *p, struct sched_attr *attr) | |
2732 | { | |
2733 | struct sched_dl_entity *dl_se = &p->dl; | |
2734 | ||
2735 | attr->sched_priority = p->rt_priority; | |
2736 | attr->sched_runtime = dl_se->dl_runtime; | |
2737 | attr->sched_deadline = dl_se->dl_deadline; | |
2738 | attr->sched_period = dl_se->dl_period; | |
2739 | attr->sched_flags = dl_se->flags; | |
2740 | } | |
2741 | ||
b4098bfc PZ |
2742 | /* |
2743 | * Default limits for DL period; on the top end we guard against small util | |
2744 | * tasks still getting rediculous long effective runtimes, on the bottom end we | |
2745 | * guard against timer DoS. | |
2746 | */ | |
2747 | unsigned int sysctl_sched_dl_period_max = 1 << 22; /* ~4 seconds */ | |
2748 | unsigned int sysctl_sched_dl_period_min = 100; /* 100 us */ | |
2749 | ||
06a76fe0 NP |
2750 | /* |
2751 | * This function validates the new parameters of a -deadline task. | |
2752 | * We ask for the deadline not being zero, and greater or equal | |
2753 | * than the runtime, as well as the period of being zero or | |
2754 | * greater than deadline. Furthermore, we have to be sure that | |
2755 | * user parameters are above the internal resolution of 1us (we | |
2756 | * check sched_runtime only since it is always the smaller one) and | |
2757 | * below 2^63 ns (we have to check both sched_deadline and | |
2758 | * sched_period, as the latter can be zero). | |
2759 | */ | |
2760 | bool __checkparam_dl(const struct sched_attr *attr) | |
2761 | { | |
b4098bfc PZ |
2762 | u64 period, max, min; |
2763 | ||
794a56eb JL |
2764 | /* special dl tasks don't actually use any parameter */ |
2765 | if (attr->sched_flags & SCHED_FLAG_SUGOV) | |
2766 | return true; | |
2767 | ||
06a76fe0 NP |
2768 | /* deadline != 0 */ |
2769 | if (attr->sched_deadline == 0) | |
2770 | return false; | |
2771 | ||
2772 | /* | |
2773 | * Since we truncate DL_SCALE bits, make sure we're at least | |
2774 | * that big. | |
2775 | */ | |
2776 | if (attr->sched_runtime < (1ULL << DL_SCALE)) | |
2777 | return false; | |
2778 | ||
2779 | /* | |
2780 | * Since we use the MSB for wrap-around and sign issues, make | |
2781 | * sure it's not set (mind that period can be equal to zero). | |
2782 | */ | |
2783 | if (attr->sched_deadline & (1ULL << 63) || | |
2784 | attr->sched_period & (1ULL << 63)) | |
2785 | return false; | |
2786 | ||
b4098bfc PZ |
2787 | period = attr->sched_period; |
2788 | if (!period) | |
2789 | period = attr->sched_deadline; | |
2790 | ||
06a76fe0 | 2791 | /* runtime <= deadline <= period (if period != 0) */ |
b4098bfc | 2792 | if (period < attr->sched_deadline || |
06a76fe0 NP |
2793 | attr->sched_deadline < attr->sched_runtime) |
2794 | return false; | |
2795 | ||
b4098bfc PZ |
2796 | max = (u64)READ_ONCE(sysctl_sched_dl_period_max) * NSEC_PER_USEC; |
2797 | min = (u64)READ_ONCE(sysctl_sched_dl_period_min) * NSEC_PER_USEC; | |
2798 | ||
2799 | if (period < min || period > max) | |
2800 | return false; | |
2801 | ||
06a76fe0 NP |
2802 | return true; |
2803 | } | |
2804 | ||
2805 | /* | |
2806 | * This function clears the sched_dl_entity static params. | |
2807 | */ | |
2808 | void __dl_clear_params(struct task_struct *p) | |
2809 | { | |
2810 | struct sched_dl_entity *dl_se = &p->dl; | |
2811 | ||
97fb7a0a IM |
2812 | dl_se->dl_runtime = 0; |
2813 | dl_se->dl_deadline = 0; | |
2814 | dl_se->dl_period = 0; | |
2815 | dl_se->flags = 0; | |
2816 | dl_se->dl_bw = 0; | |
2817 | dl_se->dl_density = 0; | |
06a76fe0 | 2818 | |
ce9bc3b2 | 2819 | dl_se->dl_boosted = 0; |
97fb7a0a IM |
2820 | dl_se->dl_throttled = 0; |
2821 | dl_se->dl_yielded = 0; | |
2822 | dl_se->dl_non_contending = 0; | |
2823 | dl_se->dl_overrun = 0; | |
06a76fe0 NP |
2824 | } |
2825 | ||
2826 | bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr) | |
2827 | { | |
2828 | struct sched_dl_entity *dl_se = &p->dl; | |
2829 | ||
2830 | if (dl_se->dl_runtime != attr->sched_runtime || | |
2831 | dl_se->dl_deadline != attr->sched_deadline || | |
2832 | dl_se->dl_period != attr->sched_period || | |
2833 | dl_se->flags != attr->sched_flags) | |
2834 | return true; | |
2835 | ||
2836 | return false; | |
2837 | } | |
2838 | ||
2839 | #ifdef CONFIG_SMP | |
2840 | int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed) | |
2841 | { | |
60ffd5ed | 2842 | unsigned long flags, cap; |
97fb7a0a | 2843 | unsigned int dest_cpu; |
06a76fe0 NP |
2844 | struct dl_bw *dl_b; |
2845 | bool overflow; | |
60ffd5ed | 2846 | int ret; |
06a76fe0 | 2847 | |
97fb7a0a IM |
2848 | dest_cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed); |
2849 | ||
06a76fe0 NP |
2850 | rcu_read_lock_sched(); |
2851 | dl_b = dl_bw_of(dest_cpu); | |
2852 | raw_spin_lock_irqsave(&dl_b->lock, flags); | |
60ffd5ed LA |
2853 | cap = dl_bw_capacity(dest_cpu); |
2854 | overflow = __dl_overflow(dl_b, cap, 0, p->dl.dl_bw); | |
97fb7a0a | 2855 | if (overflow) { |
06a76fe0 | 2856 | ret = -EBUSY; |
97fb7a0a | 2857 | } else { |
06a76fe0 NP |
2858 | /* |
2859 | * We reserve space for this task in the destination | |
2860 | * root_domain, as we can't fail after this point. | |
2861 | * We will free resources in the source root_domain | |
2862 | * later on (see set_cpus_allowed_dl()). | |
2863 | */ | |
60ffd5ed LA |
2864 | int cpus = dl_bw_cpus(dest_cpu); |
2865 | ||
06a76fe0 NP |
2866 | __dl_add(dl_b, p->dl.dl_bw, cpus); |
2867 | ret = 0; | |
2868 | } | |
2869 | raw_spin_unlock_irqrestore(&dl_b->lock, flags); | |
2870 | rcu_read_unlock_sched(); | |
97fb7a0a | 2871 | |
06a76fe0 NP |
2872 | return ret; |
2873 | } | |
2874 | ||
2875 | int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur, | |
2876 | const struct cpumask *trial) | |
2877 | { | |
2878 | int ret = 1, trial_cpus; | |
2879 | struct dl_bw *cur_dl_b; | |
2880 | unsigned long flags; | |
2881 | ||
2882 | rcu_read_lock_sched(); | |
2883 | cur_dl_b = dl_bw_of(cpumask_any(cur)); | |
2884 | trial_cpus = cpumask_weight(trial); | |
2885 | ||
2886 | raw_spin_lock_irqsave(&cur_dl_b->lock, flags); | |
2887 | if (cur_dl_b->bw != -1 && | |
2888 | cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw) | |
2889 | ret = 0; | |
2890 | raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags); | |
2891 | rcu_read_unlock_sched(); | |
97fb7a0a | 2892 | |
06a76fe0 NP |
2893 | return ret; |
2894 | } | |
2895 | ||
2896 | bool dl_cpu_busy(unsigned int cpu) | |
2897 | { | |
60ffd5ed | 2898 | unsigned long flags, cap; |
06a76fe0 NP |
2899 | struct dl_bw *dl_b; |
2900 | bool overflow; | |
06a76fe0 NP |
2901 | |
2902 | rcu_read_lock_sched(); | |
2903 | dl_b = dl_bw_of(cpu); | |
2904 | raw_spin_lock_irqsave(&dl_b->lock, flags); | |
60ffd5ed LA |
2905 | cap = dl_bw_capacity(cpu); |
2906 | overflow = __dl_overflow(dl_b, cap, 0, 0); | |
06a76fe0 NP |
2907 | raw_spin_unlock_irqrestore(&dl_b->lock, flags); |
2908 | rcu_read_unlock_sched(); | |
97fb7a0a | 2909 | |
06a76fe0 NP |
2910 | return overflow; |
2911 | } | |
2912 | #endif | |
2913 | ||
acb32132 | 2914 | #ifdef CONFIG_SCHED_DEBUG |
acb32132 WL |
2915 | void print_dl_stats(struct seq_file *m, int cpu) |
2916 | { | |
2917 | print_dl_rq(m, cpu, &cpu_rq(cpu)->dl); | |
2918 | } | |
2919 | #endif /* CONFIG_SCHED_DEBUG */ |