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aab03e05 DF |
1 | /* |
2 | * Deadline Scheduling Class (SCHED_DEADLINE) | |
3 | * | |
4 | * Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS). | |
5 | * | |
6 | * Tasks that periodically executes their instances for less than their | |
7 | * runtime won't miss any of their deadlines. | |
8 | * Tasks that are not periodic or sporadic or that tries to execute more | |
9 | * than their reserved bandwidth will be slowed down (and may potentially | |
10 | * miss some of their deadlines), and won't affect any other task. | |
11 | * | |
12 | * Copyright (C) 2012 Dario Faggioli <raistlin@linux.it>, | |
1baca4ce | 13 | * Juri Lelli <juri.lelli@gmail.com>, |
aab03e05 DF |
14 | * Michael Trimarchi <michael@amarulasolutions.com>, |
15 | * Fabio Checconi <fchecconi@gmail.com> | |
16 | */ | |
17 | #include "sched.h" | |
18 | ||
6bfd6d72 JL |
19 | #include <linux/slab.h> |
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 | ||
46 | static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq) | |
47 | { | |
48 | struct sched_dl_entity *dl_se = &p->dl; | |
49 | ||
50 | return dl_rq->rb_leftmost == &dl_se->rb_node; | |
51 | } | |
52 | ||
332ac17e DF |
53 | void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime) |
54 | { | |
55 | raw_spin_lock_init(&dl_b->dl_runtime_lock); | |
56 | dl_b->dl_period = period; | |
57 | dl_b->dl_runtime = runtime; | |
58 | } | |
59 | ||
332ac17e DF |
60 | void init_dl_bw(struct dl_bw *dl_b) |
61 | { | |
62 | raw_spin_lock_init(&dl_b->lock); | |
63 | raw_spin_lock(&def_dl_bandwidth.dl_runtime_lock); | |
1724813d | 64 | if (global_rt_runtime() == RUNTIME_INF) |
332ac17e DF |
65 | dl_b->bw = -1; |
66 | else | |
1724813d | 67 | dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime()); |
332ac17e DF |
68 | raw_spin_unlock(&def_dl_bandwidth.dl_runtime_lock); |
69 | dl_b->total_bw = 0; | |
70 | } | |
71 | ||
07c54f7a | 72 | void init_dl_rq(struct dl_rq *dl_rq) |
aab03e05 DF |
73 | { |
74 | dl_rq->rb_root = RB_ROOT; | |
1baca4ce JL |
75 | |
76 | #ifdef CONFIG_SMP | |
77 | /* zero means no -deadline tasks */ | |
78 | dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0; | |
79 | ||
80 | dl_rq->dl_nr_migratory = 0; | |
81 | dl_rq->overloaded = 0; | |
82 | dl_rq->pushable_dl_tasks_root = RB_ROOT; | |
332ac17e DF |
83 | #else |
84 | init_dl_bw(&dl_rq->dl_bw); | |
1baca4ce JL |
85 | #endif |
86 | } | |
87 | ||
88 | #ifdef CONFIG_SMP | |
89 | ||
90 | static inline int dl_overloaded(struct rq *rq) | |
91 | { | |
92 | return atomic_read(&rq->rd->dlo_count); | |
93 | } | |
94 | ||
95 | static inline void dl_set_overload(struct rq *rq) | |
96 | { | |
97 | if (!rq->online) | |
98 | return; | |
99 | ||
100 | cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask); | |
101 | /* | |
102 | * Must be visible before the overload count is | |
103 | * set (as in sched_rt.c). | |
104 | * | |
105 | * Matched by the barrier in pull_dl_task(). | |
106 | */ | |
107 | smp_wmb(); | |
108 | atomic_inc(&rq->rd->dlo_count); | |
109 | } | |
110 | ||
111 | static inline void dl_clear_overload(struct rq *rq) | |
112 | { | |
113 | if (!rq->online) | |
114 | return; | |
115 | ||
116 | atomic_dec(&rq->rd->dlo_count); | |
117 | cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask); | |
118 | } | |
119 | ||
120 | static void update_dl_migration(struct dl_rq *dl_rq) | |
121 | { | |
995b9ea4 | 122 | if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_running > 1) { |
1baca4ce JL |
123 | if (!dl_rq->overloaded) { |
124 | dl_set_overload(rq_of_dl_rq(dl_rq)); | |
125 | dl_rq->overloaded = 1; | |
126 | } | |
127 | } else if (dl_rq->overloaded) { | |
128 | dl_clear_overload(rq_of_dl_rq(dl_rq)); | |
129 | dl_rq->overloaded = 0; | |
130 | } | |
131 | } | |
132 | ||
133 | static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
134 | { | |
135 | struct task_struct *p = dl_task_of(dl_se); | |
1baca4ce | 136 | |
1baca4ce JL |
137 | if (p->nr_cpus_allowed > 1) |
138 | dl_rq->dl_nr_migratory++; | |
139 | ||
140 | update_dl_migration(dl_rq); | |
141 | } | |
142 | ||
143 | static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
144 | { | |
145 | struct task_struct *p = dl_task_of(dl_se); | |
1baca4ce | 146 | |
1baca4ce JL |
147 | if (p->nr_cpus_allowed > 1) |
148 | dl_rq->dl_nr_migratory--; | |
149 | ||
150 | update_dl_migration(dl_rq); | |
151 | } | |
152 | ||
153 | /* | |
154 | * The list of pushable -deadline task is not a plist, like in | |
155 | * sched_rt.c, it is an rb-tree with tasks ordered by deadline. | |
156 | */ | |
157 | static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p) | |
158 | { | |
159 | struct dl_rq *dl_rq = &rq->dl; | |
160 | struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_node; | |
161 | struct rb_node *parent = NULL; | |
162 | struct task_struct *entry; | |
163 | int leftmost = 1; | |
164 | ||
165 | BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks)); | |
166 | ||
167 | while (*link) { | |
168 | parent = *link; | |
169 | entry = rb_entry(parent, struct task_struct, | |
170 | pushable_dl_tasks); | |
171 | if (dl_entity_preempt(&p->dl, &entry->dl)) | |
172 | link = &parent->rb_left; | |
173 | else { | |
174 | link = &parent->rb_right; | |
175 | leftmost = 0; | |
176 | } | |
177 | } | |
178 | ||
179 | if (leftmost) | |
180 | dl_rq->pushable_dl_tasks_leftmost = &p->pushable_dl_tasks; | |
181 | ||
182 | rb_link_node(&p->pushable_dl_tasks, parent, link); | |
183 | rb_insert_color(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root); | |
aab03e05 DF |
184 | } |
185 | ||
1baca4ce JL |
186 | static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p) |
187 | { | |
188 | struct dl_rq *dl_rq = &rq->dl; | |
189 | ||
190 | if (RB_EMPTY_NODE(&p->pushable_dl_tasks)) | |
191 | return; | |
192 | ||
193 | if (dl_rq->pushable_dl_tasks_leftmost == &p->pushable_dl_tasks) { | |
194 | struct rb_node *next_node; | |
195 | ||
196 | next_node = rb_next(&p->pushable_dl_tasks); | |
197 | dl_rq->pushable_dl_tasks_leftmost = next_node; | |
198 | } | |
199 | ||
200 | rb_erase(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root); | |
201 | RB_CLEAR_NODE(&p->pushable_dl_tasks); | |
202 | } | |
203 | ||
204 | static inline int has_pushable_dl_tasks(struct rq *rq) | |
205 | { | |
206 | return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root); | |
207 | } | |
208 | ||
209 | static int push_dl_task(struct rq *rq); | |
210 | ||
dc877341 PZ |
211 | static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) |
212 | { | |
213 | return dl_task(prev); | |
214 | } | |
215 | ||
9916e214 PZ |
216 | static DEFINE_PER_CPU(struct callback_head, dl_push_head); |
217 | static DEFINE_PER_CPU(struct callback_head, dl_pull_head); | |
e3fca9e7 PZ |
218 | |
219 | static void push_dl_tasks(struct rq *); | |
9916e214 | 220 | static void pull_dl_task(struct rq *); |
e3fca9e7 PZ |
221 | |
222 | static inline void queue_push_tasks(struct rq *rq) | |
dc877341 | 223 | { |
e3fca9e7 PZ |
224 | if (!has_pushable_dl_tasks(rq)) |
225 | return; | |
226 | ||
9916e214 PZ |
227 | queue_balance_callback(rq, &per_cpu(dl_push_head, rq->cpu), push_dl_tasks); |
228 | } | |
229 | ||
230 | static inline void queue_pull_task(struct rq *rq) | |
231 | { | |
232 | queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task); | |
dc877341 PZ |
233 | } |
234 | ||
fa9c9d10 WL |
235 | static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq); |
236 | ||
a649f237 | 237 | static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p) |
fa9c9d10 WL |
238 | { |
239 | struct rq *later_rq = NULL; | |
240 | bool fallback = false; | |
241 | ||
242 | later_rq = find_lock_later_rq(p, rq); | |
243 | ||
244 | if (!later_rq) { | |
245 | int cpu; | |
246 | ||
247 | /* | |
248 | * If we cannot preempt any rq, fall back to pick any | |
249 | * online cpu. | |
250 | */ | |
251 | fallback = true; | |
252 | cpu = cpumask_any_and(cpu_active_mask, tsk_cpus_allowed(p)); | |
253 | if (cpu >= nr_cpu_ids) { | |
254 | /* | |
255 | * Fail to find any suitable cpu. | |
256 | * The task will never come back! | |
257 | */ | |
258 | BUG_ON(dl_bandwidth_enabled()); | |
259 | ||
260 | /* | |
261 | * If admission control is disabled we | |
262 | * try a little harder to let the task | |
263 | * run. | |
264 | */ | |
265 | cpu = cpumask_any(cpu_active_mask); | |
266 | } | |
267 | later_rq = cpu_rq(cpu); | |
268 | double_lock_balance(rq, later_rq); | |
269 | } | |
270 | ||
a649f237 PZ |
271 | /* |
272 | * By now the task is replenished and enqueued; migrate it. | |
273 | */ | |
fa9c9d10 WL |
274 | deactivate_task(rq, p, 0); |
275 | set_task_cpu(p, later_rq->cpu); | |
a649f237 | 276 | activate_task(later_rq, p, 0); |
fa9c9d10 WL |
277 | |
278 | if (!fallback) | |
279 | resched_curr(later_rq); | |
280 | ||
a649f237 PZ |
281 | double_unlock_balance(later_rq, rq); |
282 | ||
283 | return later_rq; | |
fa9c9d10 WL |
284 | } |
285 | ||
1baca4ce JL |
286 | #else |
287 | ||
288 | static inline | |
289 | void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p) | |
290 | { | |
291 | } | |
292 | ||
293 | static inline | |
294 | void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p) | |
295 | { | |
296 | } | |
297 | ||
298 | static inline | |
299 | void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
300 | { | |
301 | } | |
302 | ||
303 | static inline | |
304 | void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
305 | { | |
306 | } | |
307 | ||
dc877341 PZ |
308 | static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) |
309 | { | |
310 | return false; | |
311 | } | |
312 | ||
0ea60c20 | 313 | static inline void pull_dl_task(struct rq *rq) |
dc877341 | 314 | { |
dc877341 PZ |
315 | } |
316 | ||
e3fca9e7 | 317 | static inline void queue_push_tasks(struct rq *rq) |
dc877341 | 318 | { |
dc877341 PZ |
319 | } |
320 | ||
9916e214 | 321 | static inline void queue_pull_task(struct rq *rq) |
dc877341 PZ |
322 | { |
323 | } | |
1baca4ce JL |
324 | #endif /* CONFIG_SMP */ |
325 | ||
aab03e05 DF |
326 | static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags); |
327 | static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags); | |
328 | static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, | |
329 | int flags); | |
330 | ||
331 | /* | |
332 | * We are being explicitly informed that a new instance is starting, | |
333 | * and this means that: | |
334 | * - the absolute deadline of the entity has to be placed at | |
335 | * current time + relative deadline; | |
336 | * - the runtime of the entity has to be set to the maximum value. | |
337 | * | |
338 | * The capability of specifying such event is useful whenever a -deadline | |
339 | * entity wants to (try to!) synchronize its behaviour with the scheduler's | |
340 | * one, and to (try to!) reconcile itself with its own scheduling | |
341 | * parameters. | |
342 | */ | |
2d3d891d DF |
343 | static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se, |
344 | struct sched_dl_entity *pi_se) | |
aab03e05 DF |
345 | { |
346 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
347 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
348 | ||
349 | WARN_ON(!dl_se->dl_new || dl_se->dl_throttled); | |
350 | ||
351 | /* | |
352 | * We use the regular wall clock time to set deadlines in the | |
353 | * future; in fact, we must consider execution overheads (time | |
354 | * spent on hardirq context, etc.). | |
355 | */ | |
2d3d891d DF |
356 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; |
357 | dl_se->runtime = pi_se->dl_runtime; | |
aab03e05 DF |
358 | dl_se->dl_new = 0; |
359 | } | |
360 | ||
361 | /* | |
362 | * Pure Earliest Deadline First (EDF) scheduling does not deal with the | |
363 | * possibility of a entity lasting more than what it declared, and thus | |
364 | * exhausting its runtime. | |
365 | * | |
366 | * Here we are interested in making runtime overrun possible, but we do | |
367 | * not want a entity which is misbehaving to affect the scheduling of all | |
368 | * other entities. | |
369 | * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS) | |
370 | * is used, in order to confine each entity within its own bandwidth. | |
371 | * | |
372 | * This function deals exactly with that, and ensures that when the runtime | |
373 | * of a entity is replenished, its deadline is also postponed. That ensures | |
374 | * the overrunning entity can't interfere with other entity in the system and | |
375 | * can't make them miss their deadlines. Reasons why this kind of overruns | |
376 | * could happen are, typically, a entity voluntarily trying to overcome its | |
1b09d29b | 377 | * runtime, or it just underestimated it during sched_setattr(). |
aab03e05 | 378 | */ |
2d3d891d DF |
379 | static void replenish_dl_entity(struct sched_dl_entity *dl_se, |
380 | struct sched_dl_entity *pi_se) | |
aab03e05 DF |
381 | { |
382 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
383 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
384 | ||
2d3d891d DF |
385 | BUG_ON(pi_se->dl_runtime <= 0); |
386 | ||
387 | /* | |
388 | * This could be the case for a !-dl task that is boosted. | |
389 | * Just go with full inherited parameters. | |
390 | */ | |
391 | if (dl_se->dl_deadline == 0) { | |
392 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; | |
393 | dl_se->runtime = pi_se->dl_runtime; | |
394 | } | |
395 | ||
aab03e05 DF |
396 | /* |
397 | * We keep moving the deadline away until we get some | |
398 | * available runtime for the entity. This ensures correct | |
399 | * handling of situations where the runtime overrun is | |
400 | * arbitrary large. | |
401 | */ | |
402 | while (dl_se->runtime <= 0) { | |
2d3d891d DF |
403 | dl_se->deadline += pi_se->dl_period; |
404 | dl_se->runtime += pi_se->dl_runtime; | |
aab03e05 DF |
405 | } |
406 | ||
407 | /* | |
408 | * At this point, the deadline really should be "in | |
409 | * the future" with respect to rq->clock. If it's | |
410 | * not, we are, for some reason, lagging too much! | |
411 | * Anyway, after having warn userspace abut that, | |
412 | * we still try to keep the things running by | |
413 | * resetting the deadline and the budget of the | |
414 | * entity. | |
415 | */ | |
416 | if (dl_time_before(dl_se->deadline, rq_clock(rq))) { | |
c224815d | 417 | printk_deferred_once("sched: DL replenish lagged to much\n"); |
2d3d891d DF |
418 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; |
419 | dl_se->runtime = pi_se->dl_runtime; | |
aab03e05 | 420 | } |
1019a359 PZ |
421 | |
422 | if (dl_se->dl_yielded) | |
423 | dl_se->dl_yielded = 0; | |
424 | if (dl_se->dl_throttled) | |
425 | dl_se->dl_throttled = 0; | |
aab03e05 DF |
426 | } |
427 | ||
428 | /* | |
429 | * Here we check if --at time t-- an entity (which is probably being | |
430 | * [re]activated or, in general, enqueued) can use its remaining runtime | |
431 | * and its current deadline _without_ exceeding the bandwidth it is | |
432 | * assigned (function returns true if it can't). We are in fact applying | |
433 | * one of the CBS rules: when a task wakes up, if the residual runtime | |
434 | * over residual deadline fits within the allocated bandwidth, then we | |
435 | * can keep the current (absolute) deadline and residual budget without | |
436 | * disrupting the schedulability of the system. Otherwise, we should | |
437 | * refill the runtime and set the deadline a period in the future, | |
438 | * because keeping the current (absolute) deadline of the task would | |
712e5e34 DF |
439 | * result in breaking guarantees promised to other tasks (refer to |
440 | * Documentation/scheduler/sched-deadline.txt for more informations). | |
aab03e05 DF |
441 | * |
442 | * This function returns true if: | |
443 | * | |
755378a4 | 444 | * runtime / (deadline - t) > dl_runtime / dl_period , |
aab03e05 DF |
445 | * |
446 | * IOW we can't recycle current parameters. | |
755378a4 HG |
447 | * |
448 | * Notice that the bandwidth check is done against the period. For | |
449 | * task with deadline equal to period this is the same of using | |
450 | * dl_deadline instead of dl_period in the equation above. | |
aab03e05 | 451 | */ |
2d3d891d DF |
452 | static bool dl_entity_overflow(struct sched_dl_entity *dl_se, |
453 | struct sched_dl_entity *pi_se, u64 t) | |
aab03e05 DF |
454 | { |
455 | u64 left, right; | |
456 | ||
457 | /* | |
458 | * left and right are the two sides of the equation above, | |
459 | * after a bit of shuffling to use multiplications instead | |
460 | * of divisions. | |
461 | * | |
462 | * Note that none of the time values involved in the two | |
463 | * multiplications are absolute: dl_deadline and dl_runtime | |
464 | * are the relative deadline and the maximum runtime of each | |
465 | * instance, runtime is the runtime left for the last instance | |
466 | * and (deadline - t), since t is rq->clock, is the time left | |
467 | * to the (absolute) deadline. Even if overflowing the u64 type | |
468 | * is very unlikely to occur in both cases, here we scale down | |
469 | * as we want to avoid that risk at all. Scaling down by 10 | |
470 | * means that we reduce granularity to 1us. We are fine with it, | |
471 | * since this is only a true/false check and, anyway, thinking | |
472 | * of anything below microseconds resolution is actually fiction | |
473 | * (but still we want to give the user that illusion >;). | |
474 | */ | |
332ac17e DF |
475 | left = (pi_se->dl_period >> DL_SCALE) * (dl_se->runtime >> DL_SCALE); |
476 | right = ((dl_se->deadline - t) >> DL_SCALE) * | |
477 | (pi_se->dl_runtime >> DL_SCALE); | |
aab03e05 DF |
478 | |
479 | return dl_time_before(right, left); | |
480 | } | |
481 | ||
482 | /* | |
483 | * When a -deadline entity is queued back on the runqueue, its runtime and | |
484 | * deadline might need updating. | |
485 | * | |
486 | * The policy here is that we update the deadline of the entity only if: | |
487 | * - the current deadline is in the past, | |
488 | * - using the remaining runtime with the current deadline would make | |
489 | * the entity exceed its bandwidth. | |
490 | */ | |
2d3d891d DF |
491 | static void update_dl_entity(struct sched_dl_entity *dl_se, |
492 | struct sched_dl_entity *pi_se) | |
aab03e05 DF |
493 | { |
494 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
495 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
496 | ||
497 | /* | |
498 | * The arrival of a new instance needs special treatment, i.e., | |
499 | * the actual scheduling parameters have to be "renewed". | |
500 | */ | |
501 | if (dl_se->dl_new) { | |
2d3d891d | 502 | setup_new_dl_entity(dl_se, pi_se); |
aab03e05 DF |
503 | return; |
504 | } | |
505 | ||
506 | if (dl_time_before(dl_se->deadline, rq_clock(rq)) || | |
2d3d891d DF |
507 | dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) { |
508 | dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; | |
509 | dl_se->runtime = pi_se->dl_runtime; | |
aab03e05 DF |
510 | } |
511 | } | |
512 | ||
513 | /* | |
514 | * If the entity depleted all its runtime, and if we want it to sleep | |
515 | * while waiting for some new execution time to become available, we | |
516 | * set the bandwidth enforcement timer to the replenishment instant | |
517 | * and try to activate it. | |
518 | * | |
519 | * Notice that it is important for the caller to know if the timer | |
520 | * actually started or not (i.e., the replenishment instant is in | |
521 | * the future or in the past). | |
522 | */ | |
a649f237 | 523 | static int start_dl_timer(struct task_struct *p) |
aab03e05 | 524 | { |
a649f237 PZ |
525 | struct sched_dl_entity *dl_se = &p->dl; |
526 | struct hrtimer *timer = &dl_se->dl_timer; | |
527 | struct rq *rq = task_rq(p); | |
aab03e05 | 528 | ktime_t now, act; |
aab03e05 DF |
529 | s64 delta; |
530 | ||
a649f237 PZ |
531 | lockdep_assert_held(&rq->lock); |
532 | ||
aab03e05 DF |
533 | /* |
534 | * We want the timer to fire at the deadline, but considering | |
535 | * that it is actually coming from rq->clock and not from | |
536 | * hrtimer's time base reading. | |
537 | */ | |
538 | act = ns_to_ktime(dl_se->deadline); | |
a649f237 | 539 | now = hrtimer_cb_get_time(timer); |
aab03e05 DF |
540 | delta = ktime_to_ns(now) - rq_clock(rq); |
541 | act = ktime_add_ns(act, delta); | |
542 | ||
543 | /* | |
544 | * If the expiry time already passed, e.g., because the value | |
545 | * chosen as the deadline is too small, don't even try to | |
546 | * start the timer in the past! | |
547 | */ | |
548 | if (ktime_us_delta(act, now) < 0) | |
549 | return 0; | |
550 | ||
a649f237 PZ |
551 | /* |
552 | * !enqueued will guarantee another callback; even if one is already in | |
553 | * progress. This ensures a balanced {get,put}_task_struct(). | |
554 | * | |
555 | * The race against __run_timer() clearing the enqueued state is | |
556 | * harmless because we're holding task_rq()->lock, therefore the timer | |
557 | * expiring after we've done the check will wait on its task_rq_lock() | |
558 | * and observe our state. | |
559 | */ | |
560 | if (!hrtimer_is_queued(timer)) { | |
561 | get_task_struct(p); | |
562 | hrtimer_start(timer, act, HRTIMER_MODE_ABS); | |
563 | } | |
aab03e05 | 564 | |
cc9684d3 | 565 | return 1; |
aab03e05 DF |
566 | } |
567 | ||
568 | /* | |
569 | * This is the bandwidth enforcement timer callback. If here, we know | |
570 | * a task is not on its dl_rq, since the fact that the timer was running | |
571 | * means the task is throttled and needs a runtime replenishment. | |
572 | * | |
573 | * However, what we actually do depends on the fact the task is active, | |
574 | * (it is on its rq) or has been removed from there by a call to | |
575 | * dequeue_task_dl(). In the former case we must issue the runtime | |
576 | * replenishment and add the task back to the dl_rq; in the latter, we just | |
577 | * do nothing but clearing dl_throttled, so that runtime and deadline | |
578 | * updating (and the queueing back to dl_rq) will be done by the | |
579 | * next call to enqueue_task_dl(). | |
580 | */ | |
581 | static enum hrtimer_restart dl_task_timer(struct hrtimer *timer) | |
582 | { | |
583 | struct sched_dl_entity *dl_se = container_of(timer, | |
584 | struct sched_dl_entity, | |
585 | dl_timer); | |
586 | struct task_struct *p = dl_task_of(dl_se); | |
3960c8c0 | 587 | unsigned long flags; |
0f397f2c | 588 | struct rq *rq; |
3960c8c0 | 589 | |
4cd57f97 | 590 | rq = task_rq_lock(p, &flags); |
0f397f2c | 591 | |
aab03e05 | 592 | /* |
a649f237 PZ |
593 | * The task might have changed its scheduling policy to something |
594 | * different than SCHED_DEADLINE (through switched_fromd_dl()). | |
595 | */ | |
596 | if (!dl_task(p)) { | |
597 | __dl_clear_params(p); | |
598 | goto unlock; | |
599 | } | |
600 | ||
601 | /* | |
602 | * This is possible if switched_from_dl() raced against a running | |
603 | * callback that took the above !dl_task() path and we've since then | |
604 | * switched back into SCHED_DEADLINE. | |
aee38ea9 | 605 | * |
a649f237 | 606 | * There's nothing to do except drop our task reference. |
aab03e05 | 607 | */ |
a649f237 | 608 | if (dl_se->dl_new) |
aab03e05 DF |
609 | goto unlock; |
610 | ||
a649f237 PZ |
611 | /* |
612 | * The task might have been boosted by someone else and might be in the | |
613 | * boosting/deboosting path, its not throttled. | |
614 | */ | |
615 | if (dl_se->dl_boosted) | |
616 | goto unlock; | |
a79ec89f | 617 | |
fa9c9d10 | 618 | /* |
a649f237 PZ |
619 | * Spurious timer due to start_dl_timer() race; or we already received |
620 | * a replenishment from rt_mutex_setprio(). | |
fa9c9d10 | 621 | */ |
a649f237 | 622 | if (!dl_se->dl_throttled) |
fa9c9d10 | 623 | goto unlock; |
a649f237 PZ |
624 | |
625 | sched_clock_tick(); | |
626 | update_rq_clock(rq); | |
fa9c9d10 | 627 | |
a79ec89f KT |
628 | /* |
629 | * If the throttle happened during sched-out; like: | |
630 | * | |
631 | * schedule() | |
632 | * deactivate_task() | |
633 | * dequeue_task_dl() | |
634 | * update_curr_dl() | |
635 | * start_dl_timer() | |
636 | * __dequeue_task_dl() | |
637 | * prev->on_rq = 0; | |
638 | * | |
639 | * We can be both throttled and !queued. Replenish the counter | |
640 | * but do not enqueue -- wait for our wakeup to do that. | |
641 | */ | |
642 | if (!task_on_rq_queued(p)) { | |
643 | replenish_dl_entity(dl_se, dl_se); | |
644 | goto unlock; | |
645 | } | |
646 | ||
1019a359 PZ |
647 | enqueue_task_dl(rq, p, ENQUEUE_REPLENISH); |
648 | if (dl_task(rq->curr)) | |
649 | check_preempt_curr_dl(rq, p, 0); | |
650 | else | |
651 | resched_curr(rq); | |
a649f237 | 652 | |
1baca4ce | 653 | #ifdef CONFIG_SMP |
1019a359 | 654 | /* |
a649f237 PZ |
655 | * Perform balancing operations here; after the replenishments. We |
656 | * cannot drop rq->lock before this, otherwise the assertion in | |
657 | * start_dl_timer() about not missing updates is not true. | |
658 | * | |
659 | * If we find that the rq the task was on is no longer available, we | |
660 | * need to select a new rq. | |
661 | * | |
662 | * XXX figure out if select_task_rq_dl() deals with offline cpus. | |
663 | */ | |
664 | if (unlikely(!rq->online)) | |
665 | rq = dl_task_offline_migration(rq, p); | |
666 | ||
667 | /* | |
668 | * Queueing this task back might have overloaded rq, check if we need | |
669 | * to kick someone away. | |
1019a359 PZ |
670 | */ |
671 | if (has_pushable_dl_tasks(rq)) | |
672 | push_dl_task(rq); | |
1baca4ce | 673 | #endif |
a649f237 | 674 | |
aab03e05 | 675 | unlock: |
4cd57f97 | 676 | task_rq_unlock(rq, p, &flags); |
aab03e05 | 677 | |
a649f237 PZ |
678 | /* |
679 | * This can free the task_struct, including this hrtimer, do not touch | |
680 | * anything related to that after this. | |
681 | */ | |
682 | put_task_struct(p); | |
683 | ||
aab03e05 DF |
684 | return HRTIMER_NORESTART; |
685 | } | |
686 | ||
687 | void init_dl_task_timer(struct sched_dl_entity *dl_se) | |
688 | { | |
689 | struct hrtimer *timer = &dl_se->dl_timer; | |
690 | ||
aab03e05 DF |
691 | hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
692 | timer->function = dl_task_timer; | |
693 | } | |
694 | ||
695 | static | |
6fab5410 | 696 | int dl_runtime_exceeded(struct sched_dl_entity *dl_se) |
aab03e05 | 697 | { |
269ad801 | 698 | return (dl_se->runtime <= 0); |
aab03e05 DF |
699 | } |
700 | ||
faa59937 JL |
701 | extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq); |
702 | ||
aab03e05 DF |
703 | /* |
704 | * Update the current task's runtime statistics (provided it is still | |
705 | * a -deadline task and has not been removed from the dl_rq). | |
706 | */ | |
707 | static void update_curr_dl(struct rq *rq) | |
708 | { | |
709 | struct task_struct *curr = rq->curr; | |
710 | struct sched_dl_entity *dl_se = &curr->dl; | |
711 | u64 delta_exec; | |
712 | ||
713 | if (!dl_task(curr) || !on_dl_rq(dl_se)) | |
714 | return; | |
715 | ||
716 | /* | |
717 | * Consumed budget is computed considering the time as | |
718 | * observed by schedulable tasks (excluding time spent | |
719 | * in hardirq context, etc.). Deadlines are instead | |
720 | * computed using hard walltime. This seems to be the more | |
721 | * natural solution, but the full ramifications of this | |
722 | * approach need further study. | |
723 | */ | |
724 | delta_exec = rq_clock_task(rq) - curr->se.exec_start; | |
734ff2a7 KT |
725 | if (unlikely((s64)delta_exec <= 0)) |
726 | return; | |
aab03e05 DF |
727 | |
728 | schedstat_set(curr->se.statistics.exec_max, | |
729 | max(curr->se.statistics.exec_max, delta_exec)); | |
730 | ||
731 | curr->se.sum_exec_runtime += delta_exec; | |
732 | account_group_exec_runtime(curr, delta_exec); | |
733 | ||
734 | curr->se.exec_start = rq_clock_task(rq); | |
735 | cpuacct_charge(curr, delta_exec); | |
736 | ||
239be4a9 DF |
737 | sched_rt_avg_update(rq, delta_exec); |
738 | ||
80496880 | 739 | dl_se->runtime -= dl_se->dl_yielded ? 0 : delta_exec; |
6fab5410 | 740 | if (dl_runtime_exceeded(dl_se)) { |
1019a359 | 741 | dl_se->dl_throttled = 1; |
aab03e05 | 742 | __dequeue_task_dl(rq, curr, 0); |
a649f237 | 743 | if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr))) |
aab03e05 DF |
744 | enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH); |
745 | ||
746 | if (!is_leftmost(curr, &rq->dl)) | |
8875125e | 747 | resched_curr(rq); |
aab03e05 | 748 | } |
1724813d PZ |
749 | |
750 | /* | |
751 | * Because -- for now -- we share the rt bandwidth, we need to | |
752 | * account our runtime there too, otherwise actual rt tasks | |
753 | * would be able to exceed the shared quota. | |
754 | * | |
755 | * Account to the root rt group for now. | |
756 | * | |
757 | * The solution we're working towards is having the RT groups scheduled | |
758 | * using deadline servers -- however there's a few nasties to figure | |
759 | * out before that can happen. | |
760 | */ | |
761 | if (rt_bandwidth_enabled()) { | |
762 | struct rt_rq *rt_rq = &rq->rt; | |
763 | ||
764 | raw_spin_lock(&rt_rq->rt_runtime_lock); | |
1724813d PZ |
765 | /* |
766 | * We'll let actual RT tasks worry about the overflow here, we | |
faa59937 JL |
767 | * have our own CBS to keep us inline; only account when RT |
768 | * bandwidth is relevant. | |
1724813d | 769 | */ |
faa59937 JL |
770 | if (sched_rt_bandwidth_account(rt_rq)) |
771 | rt_rq->rt_time += delta_exec; | |
1724813d PZ |
772 | raw_spin_unlock(&rt_rq->rt_runtime_lock); |
773 | } | |
aab03e05 DF |
774 | } |
775 | ||
1baca4ce JL |
776 | #ifdef CONFIG_SMP |
777 | ||
778 | static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu); | |
779 | ||
780 | static inline u64 next_deadline(struct rq *rq) | |
781 | { | |
782 | struct task_struct *next = pick_next_earliest_dl_task(rq, rq->cpu); | |
783 | ||
784 | if (next && dl_prio(next->prio)) | |
785 | return next->dl.deadline; | |
786 | else | |
787 | return 0; | |
788 | } | |
789 | ||
790 | static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) | |
791 | { | |
792 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
793 | ||
794 | if (dl_rq->earliest_dl.curr == 0 || | |
795 | dl_time_before(deadline, dl_rq->earliest_dl.curr)) { | |
796 | /* | |
797 | * If the dl_rq had no -deadline tasks, or if the new task | |
798 | * has shorter deadline than the current one on dl_rq, we | |
799 | * know that the previous earliest becomes our next earliest, | |
800 | * as the new task becomes the earliest itself. | |
801 | */ | |
802 | dl_rq->earliest_dl.next = dl_rq->earliest_dl.curr; | |
803 | dl_rq->earliest_dl.curr = deadline; | |
6bfd6d72 | 804 | cpudl_set(&rq->rd->cpudl, rq->cpu, deadline, 1); |
1baca4ce JL |
805 | } else if (dl_rq->earliest_dl.next == 0 || |
806 | dl_time_before(deadline, dl_rq->earliest_dl.next)) { | |
807 | /* | |
808 | * On the other hand, if the new -deadline task has a | |
809 | * a later deadline than the earliest one on dl_rq, but | |
810 | * it is earlier than the next (if any), we must | |
811 | * recompute the next-earliest. | |
812 | */ | |
813 | dl_rq->earliest_dl.next = next_deadline(rq); | |
814 | } | |
815 | } | |
816 | ||
817 | static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) | |
818 | { | |
819 | struct rq *rq = rq_of_dl_rq(dl_rq); | |
820 | ||
821 | /* | |
822 | * Since we may have removed our earliest (and/or next earliest) | |
823 | * task we must recompute them. | |
824 | */ | |
825 | if (!dl_rq->dl_nr_running) { | |
826 | dl_rq->earliest_dl.curr = 0; | |
827 | dl_rq->earliest_dl.next = 0; | |
6bfd6d72 | 828 | cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0); |
1baca4ce JL |
829 | } else { |
830 | struct rb_node *leftmost = dl_rq->rb_leftmost; | |
831 | struct sched_dl_entity *entry; | |
832 | ||
833 | entry = rb_entry(leftmost, struct sched_dl_entity, rb_node); | |
834 | dl_rq->earliest_dl.curr = entry->deadline; | |
835 | dl_rq->earliest_dl.next = next_deadline(rq); | |
6bfd6d72 | 836 | cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline, 1); |
1baca4ce JL |
837 | } |
838 | } | |
839 | ||
840 | #else | |
841 | ||
842 | static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {} | |
843 | static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {} | |
844 | ||
845 | #endif /* CONFIG_SMP */ | |
846 | ||
847 | static inline | |
848 | void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
849 | { | |
850 | int prio = dl_task_of(dl_se)->prio; | |
851 | u64 deadline = dl_se->deadline; | |
852 | ||
853 | WARN_ON(!dl_prio(prio)); | |
854 | dl_rq->dl_nr_running++; | |
72465447 | 855 | add_nr_running(rq_of_dl_rq(dl_rq), 1); |
1baca4ce JL |
856 | |
857 | inc_dl_deadline(dl_rq, deadline); | |
858 | inc_dl_migration(dl_se, dl_rq); | |
859 | } | |
860 | ||
861 | static inline | |
862 | void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq) | |
863 | { | |
864 | int prio = dl_task_of(dl_se)->prio; | |
865 | ||
866 | WARN_ON(!dl_prio(prio)); | |
867 | WARN_ON(!dl_rq->dl_nr_running); | |
868 | dl_rq->dl_nr_running--; | |
72465447 | 869 | sub_nr_running(rq_of_dl_rq(dl_rq), 1); |
1baca4ce JL |
870 | |
871 | dec_dl_deadline(dl_rq, dl_se->deadline); | |
872 | dec_dl_migration(dl_se, dl_rq); | |
873 | } | |
874 | ||
aab03e05 DF |
875 | static void __enqueue_dl_entity(struct sched_dl_entity *dl_se) |
876 | { | |
877 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
878 | struct rb_node **link = &dl_rq->rb_root.rb_node; | |
879 | struct rb_node *parent = NULL; | |
880 | struct sched_dl_entity *entry; | |
881 | int leftmost = 1; | |
882 | ||
883 | BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node)); | |
884 | ||
885 | while (*link) { | |
886 | parent = *link; | |
887 | entry = rb_entry(parent, struct sched_dl_entity, rb_node); | |
888 | if (dl_time_before(dl_se->deadline, entry->deadline)) | |
889 | link = &parent->rb_left; | |
890 | else { | |
891 | link = &parent->rb_right; | |
892 | leftmost = 0; | |
893 | } | |
894 | } | |
895 | ||
896 | if (leftmost) | |
897 | dl_rq->rb_leftmost = &dl_se->rb_node; | |
898 | ||
899 | rb_link_node(&dl_se->rb_node, parent, link); | |
900 | rb_insert_color(&dl_se->rb_node, &dl_rq->rb_root); | |
901 | ||
1baca4ce | 902 | inc_dl_tasks(dl_se, dl_rq); |
aab03e05 DF |
903 | } |
904 | ||
905 | static void __dequeue_dl_entity(struct sched_dl_entity *dl_se) | |
906 | { | |
907 | struct dl_rq *dl_rq = dl_rq_of_se(dl_se); | |
908 | ||
909 | if (RB_EMPTY_NODE(&dl_se->rb_node)) | |
910 | return; | |
911 | ||
912 | if (dl_rq->rb_leftmost == &dl_se->rb_node) { | |
913 | struct rb_node *next_node; | |
914 | ||
915 | next_node = rb_next(&dl_se->rb_node); | |
916 | dl_rq->rb_leftmost = next_node; | |
917 | } | |
918 | ||
919 | rb_erase(&dl_se->rb_node, &dl_rq->rb_root); | |
920 | RB_CLEAR_NODE(&dl_se->rb_node); | |
921 | ||
1baca4ce | 922 | dec_dl_tasks(dl_se, dl_rq); |
aab03e05 DF |
923 | } |
924 | ||
925 | static void | |
2d3d891d DF |
926 | enqueue_dl_entity(struct sched_dl_entity *dl_se, |
927 | struct sched_dl_entity *pi_se, int flags) | |
aab03e05 DF |
928 | { |
929 | BUG_ON(on_dl_rq(dl_se)); | |
930 | ||
931 | /* | |
932 | * If this is a wakeup or a new instance, the scheduling | |
933 | * parameters of the task might need updating. Otherwise, | |
934 | * we want a replenishment of its runtime. | |
935 | */ | |
6a503c3b | 936 | if (dl_se->dl_new || flags & ENQUEUE_WAKEUP) |
2d3d891d | 937 | update_dl_entity(dl_se, pi_se); |
6a503c3b LA |
938 | else if (flags & ENQUEUE_REPLENISH) |
939 | replenish_dl_entity(dl_se, pi_se); | |
aab03e05 DF |
940 | |
941 | __enqueue_dl_entity(dl_se); | |
942 | } | |
943 | ||
944 | static void dequeue_dl_entity(struct sched_dl_entity *dl_se) | |
945 | { | |
946 | __dequeue_dl_entity(dl_se); | |
947 | } | |
948 | ||
949 | static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) | |
950 | { | |
2d3d891d DF |
951 | struct task_struct *pi_task = rt_mutex_get_top_task(p); |
952 | struct sched_dl_entity *pi_se = &p->dl; | |
953 | ||
954 | /* | |
955 | * Use the scheduling parameters of the top pi-waiter | |
ff277d42 | 956 | * task if we have one and its (absolute) deadline is |
2d3d891d DF |
957 | * smaller than our one... OTW we keep our runtime and |
958 | * deadline. | |
959 | */ | |
64be6f1f | 960 | if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) { |
2d3d891d | 961 | pi_se = &pi_task->dl; |
64be6f1f JL |
962 | } else if (!dl_prio(p->normal_prio)) { |
963 | /* | |
964 | * Special case in which we have a !SCHED_DEADLINE task | |
965 | * that is going to be deboosted, but exceedes its | |
966 | * runtime while doing so. No point in replenishing | |
967 | * it, as it's going to return back to its original | |
968 | * scheduling class after this. | |
969 | */ | |
970 | BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH); | |
971 | return; | |
972 | } | |
2d3d891d | 973 | |
aab03e05 DF |
974 | /* |
975 | * If p is throttled, we do nothing. In fact, if it exhausted | |
976 | * its budget it needs a replenishment and, since it now is on | |
977 | * its rq, the bandwidth timer callback (which clearly has not | |
978 | * run yet) will take care of this. | |
979 | */ | |
1019a359 | 980 | if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH)) |
aab03e05 DF |
981 | return; |
982 | ||
2d3d891d | 983 | enqueue_dl_entity(&p->dl, pi_se, flags); |
1baca4ce JL |
984 | |
985 | if (!task_current(rq, p) && p->nr_cpus_allowed > 1) | |
986 | enqueue_pushable_dl_task(rq, p); | |
aab03e05 DF |
987 | } |
988 | ||
989 | static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) | |
990 | { | |
991 | dequeue_dl_entity(&p->dl); | |
1baca4ce | 992 | dequeue_pushable_dl_task(rq, p); |
aab03e05 DF |
993 | } |
994 | ||
995 | static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) | |
996 | { | |
997 | update_curr_dl(rq); | |
998 | __dequeue_task_dl(rq, p, flags); | |
aab03e05 DF |
999 | } |
1000 | ||
1001 | /* | |
1002 | * Yield task semantic for -deadline tasks is: | |
1003 | * | |
1004 | * get off from the CPU until our next instance, with | |
1005 | * a new runtime. This is of little use now, since we | |
1006 | * don't have a bandwidth reclaiming mechanism. Anyway, | |
1007 | * bandwidth reclaiming is planned for the future, and | |
1008 | * yield_task_dl will indicate that some spare budget | |
1009 | * is available for other task instances to use it. | |
1010 | */ | |
1011 | static void yield_task_dl(struct rq *rq) | |
1012 | { | |
1013 | struct task_struct *p = rq->curr; | |
1014 | ||
1015 | /* | |
1016 | * We make the task go to sleep until its current deadline by | |
1017 | * forcing its runtime to zero. This way, update_curr_dl() stops | |
1018 | * it and the bandwidth timer will wake it up and will give it | |
5bfd126e | 1019 | * new scheduling parameters (thanks to dl_yielded=1). |
aab03e05 DF |
1020 | */ |
1021 | if (p->dl.runtime > 0) { | |
5bfd126e | 1022 | rq->curr->dl.dl_yielded = 1; |
aab03e05 DF |
1023 | p->dl.runtime = 0; |
1024 | } | |
6f1607f1 | 1025 | update_rq_clock(rq); |
aab03e05 | 1026 | update_curr_dl(rq); |
44fb085b WL |
1027 | /* |
1028 | * Tell update_rq_clock() that we've just updated, | |
1029 | * so we don't do microscopic update in schedule() | |
1030 | * and double the fastpath cost. | |
1031 | */ | |
1032 | rq_clock_skip_update(rq, true); | |
aab03e05 DF |
1033 | } |
1034 | ||
1baca4ce JL |
1035 | #ifdef CONFIG_SMP |
1036 | ||
1037 | static int find_later_rq(struct task_struct *task); | |
1baca4ce JL |
1038 | |
1039 | static int | |
1040 | select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) | |
1041 | { | |
1042 | struct task_struct *curr; | |
1043 | struct rq *rq; | |
1044 | ||
1d7e974c | 1045 | if (sd_flag != SD_BALANCE_WAKE) |
1baca4ce JL |
1046 | goto out; |
1047 | ||
1048 | rq = cpu_rq(cpu); | |
1049 | ||
1050 | rcu_read_lock(); | |
316c1608 | 1051 | curr = READ_ONCE(rq->curr); /* unlocked access */ |
1baca4ce JL |
1052 | |
1053 | /* | |
1054 | * If we are dealing with a -deadline task, we must | |
1055 | * decide where to wake it up. | |
1056 | * If it has a later deadline and the current task | |
1057 | * on this rq can't move (provided the waking task | |
1058 | * can!) we prefer to send it somewhere else. On the | |
1059 | * other hand, if it has a shorter deadline, we | |
1060 | * try to make it stay here, it might be important. | |
1061 | */ | |
1062 | if (unlikely(dl_task(curr)) && | |
1063 | (curr->nr_cpus_allowed < 2 || | |
1064 | !dl_entity_preempt(&p->dl, &curr->dl)) && | |
1065 | (p->nr_cpus_allowed > 1)) { | |
1066 | int target = find_later_rq(p); | |
1067 | ||
9d514262 WL |
1068 | if (target != -1 && |
1069 | dl_time_before(p->dl.deadline, | |
1070 | cpu_rq(target)->dl.earliest_dl.curr)) | |
1baca4ce JL |
1071 | cpu = target; |
1072 | } | |
1073 | rcu_read_unlock(); | |
1074 | ||
1075 | out: | |
1076 | return cpu; | |
1077 | } | |
1078 | ||
1079 | static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p) | |
1080 | { | |
1081 | /* | |
1082 | * Current can't be migrated, useless to reschedule, | |
1083 | * let's hope p can move out. | |
1084 | */ | |
1085 | if (rq->curr->nr_cpus_allowed == 1 || | |
6bfd6d72 | 1086 | cpudl_find(&rq->rd->cpudl, rq->curr, NULL) == -1) |
1baca4ce JL |
1087 | return; |
1088 | ||
1089 | /* | |
1090 | * p is migratable, so let's not schedule it and | |
1091 | * see if it is pushed or pulled somewhere else. | |
1092 | */ | |
1093 | if (p->nr_cpus_allowed != 1 && | |
6bfd6d72 | 1094 | cpudl_find(&rq->rd->cpudl, p, NULL) != -1) |
1baca4ce JL |
1095 | return; |
1096 | ||
8875125e | 1097 | resched_curr(rq); |
1baca4ce JL |
1098 | } |
1099 | ||
1100 | #endif /* CONFIG_SMP */ | |
1101 | ||
aab03e05 DF |
1102 | /* |
1103 | * Only called when both the current and waking task are -deadline | |
1104 | * tasks. | |
1105 | */ | |
1106 | static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, | |
1107 | int flags) | |
1108 | { | |
1baca4ce | 1109 | if (dl_entity_preempt(&p->dl, &rq->curr->dl)) { |
8875125e | 1110 | resched_curr(rq); |
1baca4ce JL |
1111 | return; |
1112 | } | |
1113 | ||
1114 | #ifdef CONFIG_SMP | |
1115 | /* | |
1116 | * In the unlikely case current and p have the same deadline | |
1117 | * let us try to decide what's the best thing to do... | |
1118 | */ | |
332ac17e DF |
1119 | if ((p->dl.deadline == rq->curr->dl.deadline) && |
1120 | !test_tsk_need_resched(rq->curr)) | |
1baca4ce JL |
1121 | check_preempt_equal_dl(rq, p); |
1122 | #endif /* CONFIG_SMP */ | |
aab03e05 DF |
1123 | } |
1124 | ||
1125 | #ifdef CONFIG_SCHED_HRTICK | |
1126 | static void start_hrtick_dl(struct rq *rq, struct task_struct *p) | |
1127 | { | |
177ef2a6 | 1128 | hrtick_start(rq, p->dl.runtime); |
aab03e05 | 1129 | } |
36ce9881 WL |
1130 | #else /* !CONFIG_SCHED_HRTICK */ |
1131 | static void start_hrtick_dl(struct rq *rq, struct task_struct *p) | |
1132 | { | |
1133 | } | |
aab03e05 DF |
1134 | #endif |
1135 | ||
1136 | static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq, | |
1137 | struct dl_rq *dl_rq) | |
1138 | { | |
1139 | struct rb_node *left = dl_rq->rb_leftmost; | |
1140 | ||
1141 | if (!left) | |
1142 | return NULL; | |
1143 | ||
1144 | return rb_entry(left, struct sched_dl_entity, rb_node); | |
1145 | } | |
1146 | ||
606dba2e | 1147 | struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev) |
aab03e05 DF |
1148 | { |
1149 | struct sched_dl_entity *dl_se; | |
1150 | struct task_struct *p; | |
1151 | struct dl_rq *dl_rq; | |
1152 | ||
1153 | dl_rq = &rq->dl; | |
1154 | ||
a1d9a323 | 1155 | if (need_pull_dl_task(rq, prev)) { |
cbce1a68 PZ |
1156 | /* |
1157 | * This is OK, because current is on_cpu, which avoids it being | |
1158 | * picked for load-balance and preemption/IRQs are still | |
1159 | * disabled avoiding further scheduler activity on it and we're | |
1160 | * being very careful to re-start the picking loop. | |
1161 | */ | |
1162 | lockdep_unpin_lock(&rq->lock); | |
38033c37 | 1163 | pull_dl_task(rq); |
cbce1a68 | 1164 | lockdep_pin_lock(&rq->lock); |
a1d9a323 KT |
1165 | /* |
1166 | * pull_rt_task() can drop (and re-acquire) rq->lock; this | |
1167 | * means a stop task can slip in, in which case we need to | |
1168 | * re-start task selection. | |
1169 | */ | |
da0c1e65 | 1170 | if (rq->stop && task_on_rq_queued(rq->stop)) |
a1d9a323 KT |
1171 | return RETRY_TASK; |
1172 | } | |
1173 | ||
734ff2a7 KT |
1174 | /* |
1175 | * When prev is DL, we may throttle it in put_prev_task(). | |
1176 | * So, we update time before we check for dl_nr_running. | |
1177 | */ | |
1178 | if (prev->sched_class == &dl_sched_class) | |
1179 | update_curr_dl(rq); | |
38033c37 | 1180 | |
aab03e05 DF |
1181 | if (unlikely(!dl_rq->dl_nr_running)) |
1182 | return NULL; | |
1183 | ||
3f1d2a31 | 1184 | put_prev_task(rq, prev); |
606dba2e | 1185 | |
aab03e05 DF |
1186 | dl_se = pick_next_dl_entity(rq, dl_rq); |
1187 | BUG_ON(!dl_se); | |
1188 | ||
1189 | p = dl_task_of(dl_se); | |
1190 | p->se.exec_start = rq_clock_task(rq); | |
1baca4ce JL |
1191 | |
1192 | /* Running task will never be pushed. */ | |
71362650 | 1193 | dequeue_pushable_dl_task(rq, p); |
1baca4ce | 1194 | |
aab03e05 DF |
1195 | if (hrtick_enabled(rq)) |
1196 | start_hrtick_dl(rq, p); | |
1baca4ce | 1197 | |
e3fca9e7 | 1198 | queue_push_tasks(rq); |
1baca4ce | 1199 | |
aab03e05 DF |
1200 | return p; |
1201 | } | |
1202 | ||
1203 | static void put_prev_task_dl(struct rq *rq, struct task_struct *p) | |
1204 | { | |
1205 | update_curr_dl(rq); | |
1baca4ce JL |
1206 | |
1207 | if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1) | |
1208 | enqueue_pushable_dl_task(rq, p); | |
aab03e05 DF |
1209 | } |
1210 | ||
1211 | static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued) | |
1212 | { | |
1213 | update_curr_dl(rq); | |
1214 | ||
a7bebf48 WL |
1215 | /* |
1216 | * Even when we have runtime, update_curr_dl() might have resulted in us | |
1217 | * not being the leftmost task anymore. In that case NEED_RESCHED will | |
1218 | * be set and schedule() will start a new hrtick for the next task. | |
1219 | */ | |
1220 | if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 && | |
1221 | is_leftmost(p, &rq->dl)) | |
aab03e05 | 1222 | start_hrtick_dl(rq, p); |
aab03e05 DF |
1223 | } |
1224 | ||
1225 | static void task_fork_dl(struct task_struct *p) | |
1226 | { | |
1227 | /* | |
1228 | * SCHED_DEADLINE tasks cannot fork and this is achieved through | |
1229 | * sched_fork() | |
1230 | */ | |
1231 | } | |
1232 | ||
1233 | static void task_dead_dl(struct task_struct *p) | |
1234 | { | |
332ac17e DF |
1235 | struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); |
1236 | ||
1237 | /* | |
1238 | * Since we are TASK_DEAD we won't slip out of the domain! | |
1239 | */ | |
1240 | raw_spin_lock_irq(&dl_b->lock); | |
40767b0d | 1241 | /* XXX we should retain the bw until 0-lag */ |
332ac17e DF |
1242 | dl_b->total_bw -= p->dl.dl_bw; |
1243 | raw_spin_unlock_irq(&dl_b->lock); | |
aab03e05 DF |
1244 | } |
1245 | ||
1246 | static void set_curr_task_dl(struct rq *rq) | |
1247 | { | |
1248 | struct task_struct *p = rq->curr; | |
1249 | ||
1250 | p->se.exec_start = rq_clock_task(rq); | |
1baca4ce JL |
1251 | |
1252 | /* You can't push away the running task */ | |
1253 | dequeue_pushable_dl_task(rq, p); | |
1254 | } | |
1255 | ||
1256 | #ifdef CONFIG_SMP | |
1257 | ||
1258 | /* Only try algorithms three times */ | |
1259 | #define DL_MAX_TRIES 3 | |
1260 | ||
1261 | static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu) | |
1262 | { | |
1263 | if (!task_running(rq, p) && | |
1ba93d42 | 1264 | cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) |
1baca4ce | 1265 | return 1; |
1baca4ce JL |
1266 | return 0; |
1267 | } | |
1268 | ||
1269 | /* Returns the second earliest -deadline task, NULL otherwise */ | |
1270 | static struct task_struct *pick_next_earliest_dl_task(struct rq *rq, int cpu) | |
1271 | { | |
1272 | struct rb_node *next_node = rq->dl.rb_leftmost; | |
1273 | struct sched_dl_entity *dl_se; | |
1274 | struct task_struct *p = NULL; | |
1275 | ||
1276 | next_node: | |
1277 | next_node = rb_next(next_node); | |
1278 | if (next_node) { | |
1279 | dl_se = rb_entry(next_node, struct sched_dl_entity, rb_node); | |
1280 | p = dl_task_of(dl_se); | |
1281 | ||
1282 | if (pick_dl_task(rq, p, cpu)) | |
1283 | return p; | |
1284 | ||
1285 | goto next_node; | |
1286 | } | |
1287 | ||
1288 | return NULL; | |
1289 | } | |
1290 | ||
8b5e770e WL |
1291 | /* |
1292 | * Return the earliest pushable rq's task, which is suitable to be executed | |
1293 | * on the CPU, NULL otherwise: | |
1294 | */ | |
1295 | static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu) | |
1296 | { | |
1297 | struct rb_node *next_node = rq->dl.pushable_dl_tasks_leftmost; | |
1298 | struct task_struct *p = NULL; | |
1299 | ||
1300 | if (!has_pushable_dl_tasks(rq)) | |
1301 | return NULL; | |
1302 | ||
1303 | next_node: | |
1304 | if (next_node) { | |
1305 | p = rb_entry(next_node, struct task_struct, pushable_dl_tasks); | |
1306 | ||
1307 | if (pick_dl_task(rq, p, cpu)) | |
1308 | return p; | |
1309 | ||
1310 | next_node = rb_next(next_node); | |
1311 | goto next_node; | |
1312 | } | |
1313 | ||
1314 | return NULL; | |
1315 | } | |
1316 | ||
1baca4ce JL |
1317 | static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl); |
1318 | ||
1319 | static int find_later_rq(struct task_struct *task) | |
1320 | { | |
1321 | struct sched_domain *sd; | |
4ba29684 | 1322 | struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl); |
1baca4ce JL |
1323 | int this_cpu = smp_processor_id(); |
1324 | int best_cpu, cpu = task_cpu(task); | |
1325 | ||
1326 | /* Make sure the mask is initialized first */ | |
1327 | if (unlikely(!later_mask)) | |
1328 | return -1; | |
1329 | ||
1330 | if (task->nr_cpus_allowed == 1) | |
1331 | return -1; | |
1332 | ||
91ec6778 JL |
1333 | /* |
1334 | * We have to consider system topology and task affinity | |
1335 | * first, then we can look for a suitable cpu. | |
1336 | */ | |
6bfd6d72 JL |
1337 | best_cpu = cpudl_find(&task_rq(task)->rd->cpudl, |
1338 | task, later_mask); | |
1baca4ce JL |
1339 | if (best_cpu == -1) |
1340 | return -1; | |
1341 | ||
1342 | /* | |
1343 | * If we are here, some target has been found, | |
1344 | * the most suitable of which is cached in best_cpu. | |
1345 | * This is, among the runqueues where the current tasks | |
1346 | * have later deadlines than the task's one, the rq | |
1347 | * with the latest possible one. | |
1348 | * | |
1349 | * Now we check how well this matches with task's | |
1350 | * affinity and system topology. | |
1351 | * | |
1352 | * The last cpu where the task run is our first | |
1353 | * guess, since it is most likely cache-hot there. | |
1354 | */ | |
1355 | if (cpumask_test_cpu(cpu, later_mask)) | |
1356 | return cpu; | |
1357 | /* | |
1358 | * Check if this_cpu is to be skipped (i.e., it is | |
1359 | * not in the mask) or not. | |
1360 | */ | |
1361 | if (!cpumask_test_cpu(this_cpu, later_mask)) | |
1362 | this_cpu = -1; | |
1363 | ||
1364 | rcu_read_lock(); | |
1365 | for_each_domain(cpu, sd) { | |
1366 | if (sd->flags & SD_WAKE_AFFINE) { | |
1367 | ||
1368 | /* | |
1369 | * If possible, preempting this_cpu is | |
1370 | * cheaper than migrating. | |
1371 | */ | |
1372 | if (this_cpu != -1 && | |
1373 | cpumask_test_cpu(this_cpu, sched_domain_span(sd))) { | |
1374 | rcu_read_unlock(); | |
1375 | return this_cpu; | |
1376 | } | |
1377 | ||
1378 | /* | |
1379 | * Last chance: if best_cpu is valid and is | |
1380 | * in the mask, that becomes our choice. | |
1381 | */ | |
1382 | if (best_cpu < nr_cpu_ids && | |
1383 | cpumask_test_cpu(best_cpu, sched_domain_span(sd))) { | |
1384 | rcu_read_unlock(); | |
1385 | return best_cpu; | |
1386 | } | |
1387 | } | |
1388 | } | |
1389 | rcu_read_unlock(); | |
1390 | ||
1391 | /* | |
1392 | * At this point, all our guesses failed, we just return | |
1393 | * 'something', and let the caller sort the things out. | |
1394 | */ | |
1395 | if (this_cpu != -1) | |
1396 | return this_cpu; | |
1397 | ||
1398 | cpu = cpumask_any(later_mask); | |
1399 | if (cpu < nr_cpu_ids) | |
1400 | return cpu; | |
1401 | ||
1402 | return -1; | |
1403 | } | |
1404 | ||
1405 | /* Locks the rq it finds */ | |
1406 | static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq) | |
1407 | { | |
1408 | struct rq *later_rq = NULL; | |
1409 | int tries; | |
1410 | int cpu; | |
1411 | ||
1412 | for (tries = 0; tries < DL_MAX_TRIES; tries++) { | |
1413 | cpu = find_later_rq(task); | |
1414 | ||
1415 | if ((cpu == -1) || (cpu == rq->cpu)) | |
1416 | break; | |
1417 | ||
1418 | later_rq = cpu_rq(cpu); | |
1419 | ||
9d514262 WL |
1420 | if (!dl_time_before(task->dl.deadline, |
1421 | later_rq->dl.earliest_dl.curr)) { | |
1422 | /* | |
1423 | * Target rq has tasks of equal or earlier deadline, | |
1424 | * retrying does not release any lock and is unlikely | |
1425 | * to yield a different result. | |
1426 | */ | |
1427 | later_rq = NULL; | |
1428 | break; | |
1429 | } | |
1430 | ||
1baca4ce JL |
1431 | /* Retry if something changed. */ |
1432 | if (double_lock_balance(rq, later_rq)) { | |
1433 | if (unlikely(task_rq(task) != rq || | |
1434 | !cpumask_test_cpu(later_rq->cpu, | |
1435 | &task->cpus_allowed) || | |
da0c1e65 KT |
1436 | task_running(rq, task) || |
1437 | !task_on_rq_queued(task))) { | |
1baca4ce JL |
1438 | double_unlock_balance(rq, later_rq); |
1439 | later_rq = NULL; | |
1440 | break; | |
1441 | } | |
1442 | } | |
1443 | ||
1444 | /* | |
1445 | * If the rq we found has no -deadline task, or | |
1446 | * its earliest one has a later deadline than our | |
1447 | * task, the rq is a good one. | |
1448 | */ | |
1449 | if (!later_rq->dl.dl_nr_running || | |
1450 | dl_time_before(task->dl.deadline, | |
1451 | later_rq->dl.earliest_dl.curr)) | |
1452 | break; | |
1453 | ||
1454 | /* Otherwise we try again. */ | |
1455 | double_unlock_balance(rq, later_rq); | |
1456 | later_rq = NULL; | |
1457 | } | |
1458 | ||
1459 | return later_rq; | |
1460 | } | |
1461 | ||
1462 | static struct task_struct *pick_next_pushable_dl_task(struct rq *rq) | |
1463 | { | |
1464 | struct task_struct *p; | |
1465 | ||
1466 | if (!has_pushable_dl_tasks(rq)) | |
1467 | return NULL; | |
1468 | ||
1469 | p = rb_entry(rq->dl.pushable_dl_tasks_leftmost, | |
1470 | struct task_struct, pushable_dl_tasks); | |
1471 | ||
1472 | BUG_ON(rq->cpu != task_cpu(p)); | |
1473 | BUG_ON(task_current(rq, p)); | |
1474 | BUG_ON(p->nr_cpus_allowed <= 1); | |
1475 | ||
da0c1e65 | 1476 | BUG_ON(!task_on_rq_queued(p)); |
1baca4ce JL |
1477 | BUG_ON(!dl_task(p)); |
1478 | ||
1479 | return p; | |
1480 | } | |
1481 | ||
1482 | /* | |
1483 | * See if the non running -deadline tasks on this rq | |
1484 | * can be sent to some other CPU where they can preempt | |
1485 | * and start executing. | |
1486 | */ | |
1487 | static int push_dl_task(struct rq *rq) | |
1488 | { | |
1489 | struct task_struct *next_task; | |
1490 | struct rq *later_rq; | |
c51b8ab5 | 1491 | int ret = 0; |
1baca4ce JL |
1492 | |
1493 | if (!rq->dl.overloaded) | |
1494 | return 0; | |
1495 | ||
1496 | next_task = pick_next_pushable_dl_task(rq); | |
1497 | if (!next_task) | |
1498 | return 0; | |
1499 | ||
1500 | retry: | |
1501 | if (unlikely(next_task == rq->curr)) { | |
1502 | WARN_ON(1); | |
1503 | return 0; | |
1504 | } | |
1505 | ||
1506 | /* | |
1507 | * If next_task preempts rq->curr, and rq->curr | |
1508 | * can move away, it makes sense to just reschedule | |
1509 | * without going further in pushing next_task. | |
1510 | */ | |
1511 | if (dl_task(rq->curr) && | |
1512 | dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) && | |
1513 | rq->curr->nr_cpus_allowed > 1) { | |
8875125e | 1514 | resched_curr(rq); |
1baca4ce JL |
1515 | return 0; |
1516 | } | |
1517 | ||
1518 | /* We might release rq lock */ | |
1519 | get_task_struct(next_task); | |
1520 | ||
1521 | /* Will lock the rq it'll find */ | |
1522 | later_rq = find_lock_later_rq(next_task, rq); | |
1523 | if (!later_rq) { | |
1524 | struct task_struct *task; | |
1525 | ||
1526 | /* | |
1527 | * We must check all this again, since | |
1528 | * find_lock_later_rq releases rq->lock and it is | |
1529 | * then possible that next_task has migrated. | |
1530 | */ | |
1531 | task = pick_next_pushable_dl_task(rq); | |
1532 | if (task_cpu(next_task) == rq->cpu && task == next_task) { | |
1533 | /* | |
1534 | * The task is still there. We don't try | |
1535 | * again, some other cpu will pull it when ready. | |
1536 | */ | |
1baca4ce JL |
1537 | goto out; |
1538 | } | |
1539 | ||
1540 | if (!task) | |
1541 | /* No more tasks */ | |
1542 | goto out; | |
1543 | ||
1544 | put_task_struct(next_task); | |
1545 | next_task = task; | |
1546 | goto retry; | |
1547 | } | |
1548 | ||
1549 | deactivate_task(rq, next_task, 0); | |
1550 | set_task_cpu(next_task, later_rq->cpu); | |
1551 | activate_task(later_rq, next_task, 0); | |
c51b8ab5 | 1552 | ret = 1; |
1baca4ce | 1553 | |
8875125e | 1554 | resched_curr(later_rq); |
1baca4ce JL |
1555 | |
1556 | double_unlock_balance(rq, later_rq); | |
1557 | ||
1558 | out: | |
1559 | put_task_struct(next_task); | |
1560 | ||
c51b8ab5 | 1561 | return ret; |
1baca4ce JL |
1562 | } |
1563 | ||
1564 | static void push_dl_tasks(struct rq *rq) | |
1565 | { | |
4ffa08ed | 1566 | /* push_dl_task() will return true if it moved a -deadline task */ |
1baca4ce JL |
1567 | while (push_dl_task(rq)) |
1568 | ; | |
aab03e05 DF |
1569 | } |
1570 | ||
0ea60c20 | 1571 | static void pull_dl_task(struct rq *this_rq) |
1baca4ce | 1572 | { |
0ea60c20 | 1573 | int this_cpu = this_rq->cpu, cpu; |
1baca4ce | 1574 | struct task_struct *p; |
0ea60c20 | 1575 | bool resched = false; |
1baca4ce JL |
1576 | struct rq *src_rq; |
1577 | u64 dmin = LONG_MAX; | |
1578 | ||
1579 | if (likely(!dl_overloaded(this_rq))) | |
0ea60c20 | 1580 | return; |
1baca4ce JL |
1581 | |
1582 | /* | |
1583 | * Match the barrier from dl_set_overloaded; this guarantees that if we | |
1584 | * see overloaded we must also see the dlo_mask bit. | |
1585 | */ | |
1586 | smp_rmb(); | |
1587 | ||
1588 | for_each_cpu(cpu, this_rq->rd->dlo_mask) { | |
1589 | if (this_cpu == cpu) | |
1590 | continue; | |
1591 | ||
1592 | src_rq = cpu_rq(cpu); | |
1593 | ||
1594 | /* | |
1595 | * It looks racy, abd it is! However, as in sched_rt.c, | |
1596 | * we are fine with this. | |
1597 | */ | |
1598 | if (this_rq->dl.dl_nr_running && | |
1599 | dl_time_before(this_rq->dl.earliest_dl.curr, | |
1600 | src_rq->dl.earliest_dl.next)) | |
1601 | continue; | |
1602 | ||
1603 | /* Might drop this_rq->lock */ | |
1604 | double_lock_balance(this_rq, src_rq); | |
1605 | ||
1606 | /* | |
1607 | * If there are no more pullable tasks on the | |
1608 | * rq, we're done with it. | |
1609 | */ | |
1610 | if (src_rq->dl.dl_nr_running <= 1) | |
1611 | goto skip; | |
1612 | ||
8b5e770e | 1613 | p = pick_earliest_pushable_dl_task(src_rq, this_cpu); |
1baca4ce JL |
1614 | |
1615 | /* | |
1616 | * We found a task to be pulled if: | |
1617 | * - it preempts our current (if there's one), | |
1618 | * - it will preempt the last one we pulled (if any). | |
1619 | */ | |
1620 | if (p && dl_time_before(p->dl.deadline, dmin) && | |
1621 | (!this_rq->dl.dl_nr_running || | |
1622 | dl_time_before(p->dl.deadline, | |
1623 | this_rq->dl.earliest_dl.curr))) { | |
1624 | WARN_ON(p == src_rq->curr); | |
da0c1e65 | 1625 | WARN_ON(!task_on_rq_queued(p)); |
1baca4ce JL |
1626 | |
1627 | /* | |
1628 | * Then we pull iff p has actually an earlier | |
1629 | * deadline than the current task of its runqueue. | |
1630 | */ | |
1631 | if (dl_time_before(p->dl.deadline, | |
1632 | src_rq->curr->dl.deadline)) | |
1633 | goto skip; | |
1634 | ||
0ea60c20 | 1635 | resched = true; |
1baca4ce JL |
1636 | |
1637 | deactivate_task(src_rq, p, 0); | |
1638 | set_task_cpu(p, this_cpu); | |
1639 | activate_task(this_rq, p, 0); | |
1640 | dmin = p->dl.deadline; | |
1641 | ||
1642 | /* Is there any other task even earlier? */ | |
1643 | } | |
1644 | skip: | |
1645 | double_unlock_balance(this_rq, src_rq); | |
1646 | } | |
1647 | ||
0ea60c20 PZ |
1648 | if (resched) |
1649 | resched_curr(this_rq); | |
1baca4ce JL |
1650 | } |
1651 | ||
1652 | /* | |
1653 | * Since the task is not running and a reschedule is not going to happen | |
1654 | * anytime soon on its runqueue, we try pushing it away now. | |
1655 | */ | |
1656 | static void task_woken_dl(struct rq *rq, struct task_struct *p) | |
1657 | { | |
1658 | if (!task_running(rq, p) && | |
1659 | !test_tsk_need_resched(rq->curr) && | |
1baca4ce JL |
1660 | p->nr_cpus_allowed > 1 && |
1661 | dl_task(rq->curr) && | |
1662 | (rq->curr->nr_cpus_allowed < 2 || | |
6b0a563f | 1663 | !dl_entity_preempt(&p->dl, &rq->curr->dl))) { |
1baca4ce JL |
1664 | push_dl_tasks(rq); |
1665 | } | |
1666 | } | |
1667 | ||
1668 | static void set_cpus_allowed_dl(struct task_struct *p, | |
1669 | const struct cpumask *new_mask) | |
1670 | { | |
7f51412a | 1671 | struct root_domain *src_rd; |
6c37067e | 1672 | struct rq *rq; |
1baca4ce JL |
1673 | |
1674 | BUG_ON(!dl_task(p)); | |
1675 | ||
7f51412a JL |
1676 | rq = task_rq(p); |
1677 | src_rd = rq->rd; | |
1678 | /* | |
1679 | * Migrating a SCHED_DEADLINE task between exclusive | |
1680 | * cpusets (different root_domains) entails a bandwidth | |
1681 | * update. We already made space for us in the destination | |
1682 | * domain (see cpuset_can_attach()). | |
1683 | */ | |
1684 | if (!cpumask_intersects(src_rd->span, new_mask)) { | |
1685 | struct dl_bw *src_dl_b; | |
1686 | ||
1687 | src_dl_b = dl_bw_of(cpu_of(rq)); | |
1688 | /* | |
1689 | * We now free resources of the root_domain we are migrating | |
1690 | * off. In the worst case, sched_setattr() may temporary fail | |
1691 | * until we complete the update. | |
1692 | */ | |
1693 | raw_spin_lock(&src_dl_b->lock); | |
1694 | __dl_clear(src_dl_b, p->dl.dl_bw); | |
1695 | raw_spin_unlock(&src_dl_b->lock); | |
1696 | } | |
1697 | ||
6c37067e | 1698 | set_cpus_allowed_common(p, new_mask); |
1baca4ce JL |
1699 | } |
1700 | ||
1701 | /* Assumes rq->lock is held */ | |
1702 | static void rq_online_dl(struct rq *rq) | |
1703 | { | |
1704 | if (rq->dl.overloaded) | |
1705 | dl_set_overload(rq); | |
6bfd6d72 | 1706 | |
16b26943 | 1707 | cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu); |
6bfd6d72 JL |
1708 | if (rq->dl.dl_nr_running > 0) |
1709 | cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr, 1); | |
1baca4ce JL |
1710 | } |
1711 | ||
1712 | /* Assumes rq->lock is held */ | |
1713 | static void rq_offline_dl(struct rq *rq) | |
1714 | { | |
1715 | if (rq->dl.overloaded) | |
1716 | dl_clear_overload(rq); | |
6bfd6d72 JL |
1717 | |
1718 | cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0); | |
16b26943 | 1719 | cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu); |
1baca4ce JL |
1720 | } |
1721 | ||
a6c0e746 | 1722 | void __init init_sched_dl_class(void) |
1baca4ce JL |
1723 | { |
1724 | unsigned int i; | |
1725 | ||
1726 | for_each_possible_cpu(i) | |
1727 | zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i), | |
1728 | GFP_KERNEL, cpu_to_node(i)); | |
1729 | } | |
1730 | ||
1731 | #endif /* CONFIG_SMP */ | |
1732 | ||
aab03e05 DF |
1733 | static void switched_from_dl(struct rq *rq, struct task_struct *p) |
1734 | { | |
a649f237 PZ |
1735 | /* |
1736 | * Start the deadline timer; if we switch back to dl before this we'll | |
1737 | * continue consuming our current CBS slice. If we stay outside of | |
1738 | * SCHED_DEADLINE until the deadline passes, the timer will reset the | |
1739 | * task. | |
1740 | */ | |
1741 | if (!start_dl_timer(p)) | |
1742 | __dl_clear_params(p); | |
a5e7be3b | 1743 | |
1baca4ce JL |
1744 | /* |
1745 | * Since this might be the only -deadline task on the rq, | |
1746 | * this is the right place to try to pull some other one | |
1747 | * from an overloaded cpu, if any. | |
1748 | */ | |
cd660911 WL |
1749 | if (!task_on_rq_queued(p) || rq->dl.dl_nr_running) |
1750 | return; | |
1751 | ||
9916e214 | 1752 | queue_pull_task(rq); |
aab03e05 DF |
1753 | } |
1754 | ||
1baca4ce JL |
1755 | /* |
1756 | * When switching to -deadline, we may overload the rq, then | |
1757 | * we try to push someone off, if possible. | |
1758 | */ | |
aab03e05 DF |
1759 | static void switched_to_dl(struct rq *rq, struct task_struct *p) |
1760 | { | |
da0c1e65 | 1761 | if (task_on_rq_queued(p) && rq->curr != p) { |
1baca4ce | 1762 | #ifdef CONFIG_SMP |
9916e214 PZ |
1763 | if (p->nr_cpus_allowed > 1 && rq->dl.overloaded) |
1764 | queue_push_tasks(rq); | |
1765 | #else | |
1766 | if (dl_task(rq->curr)) | |
1767 | check_preempt_curr_dl(rq, p, 0); | |
1768 | else | |
1769 | resched_curr(rq); | |
1770 | #endif | |
aab03e05 DF |
1771 | } |
1772 | } | |
1773 | ||
1baca4ce JL |
1774 | /* |
1775 | * If the scheduling parameters of a -deadline task changed, | |
1776 | * a push or pull operation might be needed. | |
1777 | */ | |
aab03e05 DF |
1778 | static void prio_changed_dl(struct rq *rq, struct task_struct *p, |
1779 | int oldprio) | |
1780 | { | |
da0c1e65 | 1781 | if (task_on_rq_queued(p) || rq->curr == p) { |
aab03e05 | 1782 | #ifdef CONFIG_SMP |
1baca4ce JL |
1783 | /* |
1784 | * This might be too much, but unfortunately | |
1785 | * we don't have the old deadline value, and | |
1786 | * we can't argue if the task is increasing | |
1787 | * or lowering its prio, so... | |
1788 | */ | |
1789 | if (!rq->dl.overloaded) | |
9916e214 | 1790 | queue_pull_task(rq); |
1baca4ce JL |
1791 | |
1792 | /* | |
1793 | * If we now have a earlier deadline task than p, | |
1794 | * then reschedule, provided p is still on this | |
1795 | * runqueue. | |
1796 | */ | |
9916e214 | 1797 | if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline)) |
8875125e | 1798 | resched_curr(rq); |
1baca4ce JL |
1799 | #else |
1800 | /* | |
1801 | * Again, we don't know if p has a earlier | |
1802 | * or later deadline, so let's blindly set a | |
1803 | * (maybe not needed) rescheduling point. | |
1804 | */ | |
8875125e | 1805 | resched_curr(rq); |
1baca4ce JL |
1806 | #endif /* CONFIG_SMP */ |
1807 | } else | |
1808 | switched_to_dl(rq, p); | |
aab03e05 | 1809 | } |
aab03e05 DF |
1810 | |
1811 | const struct sched_class dl_sched_class = { | |
1812 | .next = &rt_sched_class, | |
1813 | .enqueue_task = enqueue_task_dl, | |
1814 | .dequeue_task = dequeue_task_dl, | |
1815 | .yield_task = yield_task_dl, | |
1816 | ||
1817 | .check_preempt_curr = check_preempt_curr_dl, | |
1818 | ||
1819 | .pick_next_task = pick_next_task_dl, | |
1820 | .put_prev_task = put_prev_task_dl, | |
1821 | ||
1822 | #ifdef CONFIG_SMP | |
1823 | .select_task_rq = select_task_rq_dl, | |
1baca4ce JL |
1824 | .set_cpus_allowed = set_cpus_allowed_dl, |
1825 | .rq_online = rq_online_dl, | |
1826 | .rq_offline = rq_offline_dl, | |
1baca4ce | 1827 | .task_woken = task_woken_dl, |
aab03e05 DF |
1828 | #endif |
1829 | ||
1830 | .set_curr_task = set_curr_task_dl, | |
1831 | .task_tick = task_tick_dl, | |
1832 | .task_fork = task_fork_dl, | |
1833 | .task_dead = task_dead_dl, | |
1834 | ||
1835 | .prio_changed = prio_changed_dl, | |
1836 | .switched_from = switched_from_dl, | |
1837 | .switched_to = switched_to_dl, | |
6e998916 SG |
1838 | |
1839 | .update_curr = update_curr_dl, | |
aab03e05 | 1840 | }; |
acb32132 WL |
1841 | |
1842 | #ifdef CONFIG_SCHED_DEBUG | |
1843 | extern void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq); | |
1844 | ||
1845 | void print_dl_stats(struct seq_file *m, int cpu) | |
1846 | { | |
1847 | print_dl_rq(m, cpu, &cpu_rq(cpu)->dl); | |
1848 | } | |
1849 | #endif /* CONFIG_SCHED_DEBUG */ |