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bf0f6f24 IM |
1 | /* |
2 | * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH) | |
3 | * | |
4 | * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
5 | * | |
6 | * Interactivity improvements by Mike Galbraith | |
7 | * (C) 2007 Mike Galbraith <efault@gmx.de> | |
8 | * | |
9 | * Various enhancements by Dmitry Adamushko. | |
10 | * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com> | |
11 | * | |
12 | * Group scheduling enhancements by Srivatsa Vaddagiri | |
13 | * Copyright IBM Corporation, 2007 | |
14 | * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> | |
15 | * | |
16 | * Scaled math optimizations by Thomas Gleixner | |
17 | * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de> | |
18 | */ | |
19 | ||
20 | /* | |
21 | * Preemption granularity: | |
22 | * (default: 2 msec, units: nanoseconds) | |
23 | * | |
24 | * NOTE: this granularity value is not the same as the concept of | |
25 | * 'timeslice length' - timeslices in CFS will typically be somewhat | |
26 | * larger than this value. (to see the precise effective timeslice | |
27 | * length of your workload, run vmstat and monitor the context-switches | |
28 | * field) | |
29 | * | |
30 | * On SMP systems the value of this is multiplied by the log2 of the | |
31 | * number of CPUs. (i.e. factor 2x on 2-way systems, 3x on 4-way | |
32 | * systems, 4x on 8-way systems, 5x on 16-way systems, etc.) | |
33 | */ | |
34 | unsigned int sysctl_sched_granularity __read_mostly = 2000000000ULL/HZ; | |
35 | ||
36 | /* | |
37 | * SCHED_BATCH wake-up granularity. | |
38 | * (default: 10 msec, units: nanoseconds) | |
39 | * | |
40 | * This option delays the preemption effects of decoupled workloads | |
41 | * and reduces their over-scheduling. Synchronous workloads will still | |
42 | * have immediate wakeup/sleep latencies. | |
43 | */ | |
44 | unsigned int sysctl_sched_batch_wakeup_granularity __read_mostly = | |
45 | 10000000000ULL/HZ; | |
46 | ||
47 | /* | |
48 | * SCHED_OTHER wake-up granularity. | |
49 | * (default: 1 msec, units: nanoseconds) | |
50 | * | |
51 | * This option delays the preemption effects of decoupled workloads | |
52 | * and reduces their over-scheduling. Synchronous workloads will still | |
53 | * have immediate wakeup/sleep latencies. | |
54 | */ | |
55 | unsigned int sysctl_sched_wakeup_granularity __read_mostly = 1000000000ULL/HZ; | |
56 | ||
57 | unsigned int sysctl_sched_stat_granularity __read_mostly; | |
58 | ||
59 | /* | |
60 | * Initialized in sched_init_granularity(): | |
61 | */ | |
62 | unsigned int sysctl_sched_runtime_limit __read_mostly; | |
63 | ||
64 | /* | |
65 | * Debugging: various feature bits | |
66 | */ | |
67 | enum { | |
68 | SCHED_FEAT_FAIR_SLEEPERS = 1, | |
69 | SCHED_FEAT_SLEEPER_AVG = 2, | |
70 | SCHED_FEAT_SLEEPER_LOAD_AVG = 4, | |
71 | SCHED_FEAT_PRECISE_CPU_LOAD = 8, | |
72 | SCHED_FEAT_START_DEBIT = 16, | |
73 | SCHED_FEAT_SKIP_INITIAL = 32, | |
74 | }; | |
75 | ||
76 | unsigned int sysctl_sched_features __read_mostly = | |
77 | SCHED_FEAT_FAIR_SLEEPERS *1 | | |
78 | SCHED_FEAT_SLEEPER_AVG *1 | | |
79 | SCHED_FEAT_SLEEPER_LOAD_AVG *1 | | |
80 | SCHED_FEAT_PRECISE_CPU_LOAD *1 | | |
81 | SCHED_FEAT_START_DEBIT *1 | | |
82 | SCHED_FEAT_SKIP_INITIAL *0; | |
83 | ||
84 | extern struct sched_class fair_sched_class; | |
85 | ||
86 | /************************************************************** | |
87 | * CFS operations on generic schedulable entities: | |
88 | */ | |
89 | ||
90 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
91 | ||
92 | /* cpu runqueue to which this cfs_rq is attached */ | |
93 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) | |
94 | { | |
95 | return cfs_rq->rq; | |
96 | } | |
97 | ||
98 | /* currently running entity (if any) on this cfs_rq */ | |
99 | static inline struct sched_entity *cfs_rq_curr(struct cfs_rq *cfs_rq) | |
100 | { | |
101 | return cfs_rq->curr; | |
102 | } | |
103 | ||
104 | /* An entity is a task if it doesn't "own" a runqueue */ | |
105 | #define entity_is_task(se) (!se->my_q) | |
106 | ||
107 | static inline void | |
108 | set_cfs_rq_curr(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
109 | { | |
110 | cfs_rq->curr = se; | |
111 | } | |
112 | ||
113 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
114 | ||
115 | static inline struct rq *rq_of(struct cfs_rq *cfs_rq) | |
116 | { | |
117 | return container_of(cfs_rq, struct rq, cfs); | |
118 | } | |
119 | ||
120 | static inline struct sched_entity *cfs_rq_curr(struct cfs_rq *cfs_rq) | |
121 | { | |
122 | struct rq *rq = rq_of(cfs_rq); | |
123 | ||
124 | if (unlikely(rq->curr->sched_class != &fair_sched_class)) | |
125 | return NULL; | |
126 | ||
127 | return &rq->curr->se; | |
128 | } | |
129 | ||
130 | #define entity_is_task(se) 1 | |
131 | ||
132 | static inline void | |
133 | set_cfs_rq_curr(struct cfs_rq *cfs_rq, struct sched_entity *se) { } | |
134 | ||
135 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
136 | ||
137 | static inline struct task_struct *task_of(struct sched_entity *se) | |
138 | { | |
139 | return container_of(se, struct task_struct, se); | |
140 | } | |
141 | ||
142 | ||
143 | /************************************************************** | |
144 | * Scheduling class tree data structure manipulation methods: | |
145 | */ | |
146 | ||
147 | /* | |
148 | * Enqueue an entity into the rb-tree: | |
149 | */ | |
150 | static inline void | |
151 | __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
152 | { | |
153 | struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; | |
154 | struct rb_node *parent = NULL; | |
155 | struct sched_entity *entry; | |
156 | s64 key = se->fair_key; | |
157 | int leftmost = 1; | |
158 | ||
159 | /* | |
160 | * Find the right place in the rbtree: | |
161 | */ | |
162 | while (*link) { | |
163 | parent = *link; | |
164 | entry = rb_entry(parent, struct sched_entity, run_node); | |
165 | /* | |
166 | * We dont care about collisions. Nodes with | |
167 | * the same key stay together. | |
168 | */ | |
169 | if (key - entry->fair_key < 0) { | |
170 | link = &parent->rb_left; | |
171 | } else { | |
172 | link = &parent->rb_right; | |
173 | leftmost = 0; | |
174 | } | |
175 | } | |
176 | ||
177 | /* | |
178 | * Maintain a cache of leftmost tree entries (it is frequently | |
179 | * used): | |
180 | */ | |
181 | if (leftmost) | |
182 | cfs_rq->rb_leftmost = &se->run_node; | |
183 | ||
184 | rb_link_node(&se->run_node, parent, link); | |
185 | rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline); | |
186 | update_load_add(&cfs_rq->load, se->load.weight); | |
187 | cfs_rq->nr_running++; | |
188 | se->on_rq = 1; | |
189 | } | |
190 | ||
191 | static inline void | |
192 | __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
193 | { | |
194 | if (cfs_rq->rb_leftmost == &se->run_node) | |
195 | cfs_rq->rb_leftmost = rb_next(&se->run_node); | |
196 | rb_erase(&se->run_node, &cfs_rq->tasks_timeline); | |
197 | update_load_sub(&cfs_rq->load, se->load.weight); | |
198 | cfs_rq->nr_running--; | |
199 | se->on_rq = 0; | |
200 | } | |
201 | ||
202 | static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq) | |
203 | { | |
204 | return cfs_rq->rb_leftmost; | |
205 | } | |
206 | ||
207 | static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq) | |
208 | { | |
209 | return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node); | |
210 | } | |
211 | ||
212 | /************************************************************** | |
213 | * Scheduling class statistics methods: | |
214 | */ | |
215 | ||
216 | /* | |
217 | * We rescale the rescheduling granularity of tasks according to their | |
218 | * nice level, but only linearly, not exponentially: | |
219 | */ | |
220 | static long | |
221 | niced_granularity(struct sched_entity *curr, unsigned long granularity) | |
222 | { | |
223 | u64 tmp; | |
224 | ||
225 | /* | |
226 | * Negative nice levels get the same granularity as nice-0: | |
227 | */ | |
228 | if (likely(curr->load.weight >= NICE_0_LOAD)) | |
229 | return granularity; | |
230 | /* | |
231 | * Positive nice level tasks get linearly finer | |
232 | * granularity: | |
233 | */ | |
234 | tmp = curr->load.weight * (u64)granularity; | |
235 | ||
236 | /* | |
237 | * It will always fit into 'long': | |
238 | */ | |
239 | return (long) (tmp >> NICE_0_SHIFT); | |
240 | } | |
241 | ||
242 | static inline void | |
243 | limit_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se) | |
244 | { | |
245 | long limit = sysctl_sched_runtime_limit; | |
246 | ||
247 | /* | |
248 | * Niced tasks have the same history dynamic range as | |
249 | * non-niced tasks: | |
250 | */ | |
251 | if (unlikely(se->wait_runtime > limit)) { | |
252 | se->wait_runtime = limit; | |
253 | schedstat_inc(se, wait_runtime_overruns); | |
254 | schedstat_inc(cfs_rq, wait_runtime_overruns); | |
255 | } | |
256 | if (unlikely(se->wait_runtime < -limit)) { | |
257 | se->wait_runtime = -limit; | |
258 | schedstat_inc(se, wait_runtime_underruns); | |
259 | schedstat_inc(cfs_rq, wait_runtime_underruns); | |
260 | } | |
261 | } | |
262 | ||
263 | static inline void | |
264 | __add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta) | |
265 | { | |
266 | se->wait_runtime += delta; | |
267 | schedstat_add(se, sum_wait_runtime, delta); | |
268 | limit_wait_runtime(cfs_rq, se); | |
269 | } | |
270 | ||
271 | static void | |
272 | add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta) | |
273 | { | |
274 | schedstat_add(cfs_rq, wait_runtime, -se->wait_runtime); | |
275 | __add_wait_runtime(cfs_rq, se, delta); | |
276 | schedstat_add(cfs_rq, wait_runtime, se->wait_runtime); | |
277 | } | |
278 | ||
279 | /* | |
280 | * Update the current task's runtime statistics. Skip current tasks that | |
281 | * are not in our scheduling class. | |
282 | */ | |
283 | static inline void | |
284 | __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr, u64 now) | |
285 | { | |
286 | unsigned long delta, delta_exec, delta_fair; | |
287 | long delta_mine; | |
288 | struct load_weight *lw = &cfs_rq->load; | |
289 | unsigned long load = lw->weight; | |
290 | ||
291 | if (unlikely(!load)) | |
292 | return; | |
293 | ||
294 | delta_exec = curr->delta_exec; | |
295 | #ifdef CONFIG_SCHEDSTATS | |
296 | if (unlikely(delta_exec > curr->exec_max)) | |
297 | curr->exec_max = delta_exec; | |
298 | #endif | |
299 | ||
300 | curr->sum_exec_runtime += delta_exec; | |
301 | cfs_rq->exec_clock += delta_exec; | |
302 | ||
303 | delta_fair = calc_delta_fair(delta_exec, lw); | |
304 | delta_mine = calc_delta_mine(delta_exec, curr->load.weight, lw); | |
305 | ||
306 | if (cfs_rq->sleeper_bonus > sysctl_sched_stat_granularity) { | |
307 | delta = calc_delta_mine(cfs_rq->sleeper_bonus, | |
308 | curr->load.weight, lw); | |
309 | if (unlikely(delta > cfs_rq->sleeper_bonus)) | |
310 | delta = cfs_rq->sleeper_bonus; | |
311 | ||
312 | cfs_rq->sleeper_bonus -= delta; | |
313 | delta_mine -= delta; | |
314 | } | |
315 | ||
316 | cfs_rq->fair_clock += delta_fair; | |
317 | /* | |
318 | * We executed delta_exec amount of time on the CPU, | |
319 | * but we were only entitled to delta_mine amount of | |
320 | * time during that period (if nr_running == 1 then | |
321 | * the two values are equal) | |
322 | * [Note: delta_mine - delta_exec is negative]: | |
323 | */ | |
324 | add_wait_runtime(cfs_rq, curr, delta_mine - delta_exec); | |
325 | } | |
326 | ||
327 | static void update_curr(struct cfs_rq *cfs_rq, u64 now) | |
328 | { | |
329 | struct sched_entity *curr = cfs_rq_curr(cfs_rq); | |
330 | unsigned long delta_exec; | |
331 | ||
332 | if (unlikely(!curr)) | |
333 | return; | |
334 | ||
335 | /* | |
336 | * Get the amount of time the current task was running | |
337 | * since the last time we changed load (this cannot | |
338 | * overflow on 32 bits): | |
339 | */ | |
340 | delta_exec = (unsigned long)(now - curr->exec_start); | |
341 | ||
342 | curr->delta_exec += delta_exec; | |
343 | ||
344 | if (unlikely(curr->delta_exec > sysctl_sched_stat_granularity)) { | |
345 | __update_curr(cfs_rq, curr, now); | |
346 | curr->delta_exec = 0; | |
347 | } | |
348 | curr->exec_start = now; | |
349 | } | |
350 | ||
351 | static inline void | |
352 | update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
353 | { | |
354 | se->wait_start_fair = cfs_rq->fair_clock; | |
355 | se->wait_start = now; | |
356 | } | |
357 | ||
358 | /* | |
359 | * We calculate fair deltas here, so protect against the random effects | |
360 | * of a multiplication overflow by capping it to the runtime limit: | |
361 | */ | |
362 | #if BITS_PER_LONG == 32 | |
363 | static inline unsigned long | |
364 | calc_weighted(unsigned long delta, unsigned long weight, int shift) | |
365 | { | |
366 | u64 tmp = (u64)delta * weight >> shift; | |
367 | ||
368 | if (unlikely(tmp > sysctl_sched_runtime_limit*2)) | |
369 | return sysctl_sched_runtime_limit*2; | |
370 | return tmp; | |
371 | } | |
372 | #else | |
373 | static inline unsigned long | |
374 | calc_weighted(unsigned long delta, unsigned long weight, int shift) | |
375 | { | |
376 | return delta * weight >> shift; | |
377 | } | |
378 | #endif | |
379 | ||
380 | /* | |
381 | * Task is being enqueued - update stats: | |
382 | */ | |
383 | static void | |
384 | update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
385 | { | |
386 | s64 key; | |
387 | ||
388 | /* | |
389 | * Are we enqueueing a waiting task? (for current tasks | |
390 | * a dequeue/enqueue event is a NOP) | |
391 | */ | |
392 | if (se != cfs_rq_curr(cfs_rq)) | |
393 | update_stats_wait_start(cfs_rq, se, now); | |
394 | /* | |
395 | * Update the key: | |
396 | */ | |
397 | key = cfs_rq->fair_clock; | |
398 | ||
399 | /* | |
400 | * Optimize the common nice 0 case: | |
401 | */ | |
402 | if (likely(se->load.weight == NICE_0_LOAD)) { | |
403 | key -= se->wait_runtime; | |
404 | } else { | |
405 | u64 tmp; | |
406 | ||
407 | if (se->wait_runtime < 0) { | |
408 | tmp = -se->wait_runtime; | |
409 | key += (tmp * se->load.inv_weight) >> | |
410 | (WMULT_SHIFT - NICE_0_SHIFT); | |
411 | } else { | |
412 | tmp = se->wait_runtime; | |
413 | key -= (tmp * se->load.weight) >> NICE_0_SHIFT; | |
414 | } | |
415 | } | |
416 | ||
417 | se->fair_key = key; | |
418 | } | |
419 | ||
420 | /* | |
421 | * Note: must be called with a freshly updated rq->fair_clock. | |
422 | */ | |
423 | static inline void | |
424 | __update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
425 | { | |
426 | unsigned long delta_fair = se->delta_fair_run; | |
427 | ||
428 | #ifdef CONFIG_SCHEDSTATS | |
429 | { | |
430 | s64 delta_wait = now - se->wait_start; | |
431 | if (unlikely(delta_wait > se->wait_max)) | |
432 | se->wait_max = delta_wait; | |
433 | } | |
434 | #endif | |
435 | ||
436 | if (unlikely(se->load.weight != NICE_0_LOAD)) | |
437 | delta_fair = calc_weighted(delta_fair, se->load.weight, | |
438 | NICE_0_SHIFT); | |
439 | ||
440 | add_wait_runtime(cfs_rq, se, delta_fair); | |
441 | } | |
442 | ||
443 | static void | |
444 | update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
445 | { | |
446 | unsigned long delta_fair; | |
447 | ||
448 | delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit), | |
449 | (u64)(cfs_rq->fair_clock - se->wait_start_fair)); | |
450 | ||
451 | se->delta_fair_run += delta_fair; | |
452 | if (unlikely(abs(se->delta_fair_run) >= | |
453 | sysctl_sched_stat_granularity)) { | |
454 | __update_stats_wait_end(cfs_rq, se, now); | |
455 | se->delta_fair_run = 0; | |
456 | } | |
457 | ||
458 | se->wait_start_fair = 0; | |
459 | se->wait_start = 0; | |
460 | } | |
461 | ||
462 | static inline void | |
463 | update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
464 | { | |
465 | update_curr(cfs_rq, now); | |
466 | /* | |
467 | * Mark the end of the wait period if dequeueing a | |
468 | * waiting task: | |
469 | */ | |
470 | if (se != cfs_rq_curr(cfs_rq)) | |
471 | update_stats_wait_end(cfs_rq, se, now); | |
472 | } | |
473 | ||
474 | /* | |
475 | * We are picking a new current task - update its stats: | |
476 | */ | |
477 | static inline void | |
478 | update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
479 | { | |
480 | /* | |
481 | * We are starting a new run period: | |
482 | */ | |
483 | se->exec_start = now; | |
484 | } | |
485 | ||
486 | /* | |
487 | * We are descheduling a task - update its stats: | |
488 | */ | |
489 | static inline void | |
490 | update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
491 | { | |
492 | se->exec_start = 0; | |
493 | } | |
494 | ||
495 | /************************************************** | |
496 | * Scheduling class queueing methods: | |
497 | */ | |
498 | ||
499 | static void | |
500 | __enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
501 | { | |
502 | unsigned long load = cfs_rq->load.weight, delta_fair; | |
503 | long prev_runtime; | |
504 | ||
505 | if (sysctl_sched_features & SCHED_FEAT_SLEEPER_LOAD_AVG) | |
506 | load = rq_of(cfs_rq)->cpu_load[2]; | |
507 | ||
508 | delta_fair = se->delta_fair_sleep; | |
509 | ||
510 | /* | |
511 | * Fix up delta_fair with the effect of us running | |
512 | * during the whole sleep period: | |
513 | */ | |
514 | if (sysctl_sched_features & SCHED_FEAT_SLEEPER_AVG) | |
515 | delta_fair = div64_likely32((u64)delta_fair * load, | |
516 | load + se->load.weight); | |
517 | ||
518 | if (unlikely(se->load.weight != NICE_0_LOAD)) | |
519 | delta_fair = calc_weighted(delta_fair, se->load.weight, | |
520 | NICE_0_SHIFT); | |
521 | ||
522 | prev_runtime = se->wait_runtime; | |
523 | __add_wait_runtime(cfs_rq, se, delta_fair); | |
524 | delta_fair = se->wait_runtime - prev_runtime; | |
525 | ||
526 | /* | |
527 | * Track the amount of bonus we've given to sleepers: | |
528 | */ | |
529 | cfs_rq->sleeper_bonus += delta_fair; | |
530 | ||
531 | schedstat_add(cfs_rq, wait_runtime, se->wait_runtime); | |
532 | } | |
533 | ||
534 | static void | |
535 | enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
536 | { | |
537 | struct task_struct *tsk = task_of(se); | |
538 | unsigned long delta_fair; | |
539 | ||
540 | if ((entity_is_task(se) && tsk->policy == SCHED_BATCH) || | |
541 | !(sysctl_sched_features & SCHED_FEAT_FAIR_SLEEPERS)) | |
542 | return; | |
543 | ||
544 | delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit), | |
545 | (u64)(cfs_rq->fair_clock - se->sleep_start_fair)); | |
546 | ||
547 | se->delta_fair_sleep += delta_fair; | |
548 | if (unlikely(abs(se->delta_fair_sleep) >= | |
549 | sysctl_sched_stat_granularity)) { | |
550 | __enqueue_sleeper(cfs_rq, se, now); | |
551 | se->delta_fair_sleep = 0; | |
552 | } | |
553 | ||
554 | se->sleep_start_fair = 0; | |
555 | ||
556 | #ifdef CONFIG_SCHEDSTATS | |
557 | if (se->sleep_start) { | |
558 | u64 delta = now - se->sleep_start; | |
559 | ||
560 | if ((s64)delta < 0) | |
561 | delta = 0; | |
562 | ||
563 | if (unlikely(delta > se->sleep_max)) | |
564 | se->sleep_max = delta; | |
565 | ||
566 | se->sleep_start = 0; | |
567 | se->sum_sleep_runtime += delta; | |
568 | } | |
569 | if (se->block_start) { | |
570 | u64 delta = now - se->block_start; | |
571 | ||
572 | if ((s64)delta < 0) | |
573 | delta = 0; | |
574 | ||
575 | if (unlikely(delta > se->block_max)) | |
576 | se->block_max = delta; | |
577 | ||
578 | se->block_start = 0; | |
579 | se->sum_sleep_runtime += delta; | |
580 | } | |
581 | #endif | |
582 | } | |
583 | ||
584 | static void | |
585 | enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, | |
586 | int wakeup, u64 now) | |
587 | { | |
588 | /* | |
589 | * Update the fair clock. | |
590 | */ | |
591 | update_curr(cfs_rq, now); | |
592 | ||
593 | if (wakeup) | |
594 | enqueue_sleeper(cfs_rq, se, now); | |
595 | ||
596 | update_stats_enqueue(cfs_rq, se, now); | |
597 | __enqueue_entity(cfs_rq, se); | |
598 | } | |
599 | ||
600 | static void | |
601 | dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, | |
602 | int sleep, u64 now) | |
603 | { | |
604 | update_stats_dequeue(cfs_rq, se, now); | |
605 | if (sleep) { | |
606 | se->sleep_start_fair = cfs_rq->fair_clock; | |
607 | #ifdef CONFIG_SCHEDSTATS | |
608 | if (entity_is_task(se)) { | |
609 | struct task_struct *tsk = task_of(se); | |
610 | ||
611 | if (tsk->state & TASK_INTERRUPTIBLE) | |
612 | se->sleep_start = now; | |
613 | if (tsk->state & TASK_UNINTERRUPTIBLE) | |
614 | se->block_start = now; | |
615 | } | |
616 | cfs_rq->wait_runtime -= se->wait_runtime; | |
617 | #endif | |
618 | } | |
619 | __dequeue_entity(cfs_rq, se); | |
620 | } | |
621 | ||
622 | /* | |
623 | * Preempt the current task with a newly woken task if needed: | |
624 | */ | |
625 | static void | |
626 | __check_preempt_curr_fair(struct cfs_rq *cfs_rq, struct sched_entity *se, | |
627 | struct sched_entity *curr, unsigned long granularity) | |
628 | { | |
629 | s64 __delta = curr->fair_key - se->fair_key; | |
630 | ||
631 | /* | |
632 | * Take scheduling granularity into account - do not | |
633 | * preempt the current task unless the best task has | |
634 | * a larger than sched_granularity fairness advantage: | |
635 | */ | |
636 | if (__delta > niced_granularity(curr, granularity)) | |
637 | resched_task(rq_of(cfs_rq)->curr); | |
638 | } | |
639 | ||
640 | static inline void | |
641 | set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, u64 now) | |
642 | { | |
643 | /* | |
644 | * Any task has to be enqueued before it get to execute on | |
645 | * a CPU. So account for the time it spent waiting on the | |
646 | * runqueue. (note, here we rely on pick_next_task() having | |
647 | * done a put_prev_task_fair() shortly before this, which | |
648 | * updated rq->fair_clock - used by update_stats_wait_end()) | |
649 | */ | |
650 | update_stats_wait_end(cfs_rq, se, now); | |
651 | update_stats_curr_start(cfs_rq, se, now); | |
652 | set_cfs_rq_curr(cfs_rq, se); | |
653 | } | |
654 | ||
655 | static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq, u64 now) | |
656 | { | |
657 | struct sched_entity *se = __pick_next_entity(cfs_rq); | |
658 | ||
659 | set_next_entity(cfs_rq, se, now); | |
660 | ||
661 | return se; | |
662 | } | |
663 | ||
664 | static void | |
665 | put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev, u64 now) | |
666 | { | |
667 | /* | |
668 | * If still on the runqueue then deactivate_task() | |
669 | * was not called and update_curr() has to be done: | |
670 | */ | |
671 | if (prev->on_rq) | |
672 | update_curr(cfs_rq, now); | |
673 | ||
674 | update_stats_curr_end(cfs_rq, prev, now); | |
675 | ||
676 | if (prev->on_rq) | |
677 | update_stats_wait_start(cfs_rq, prev, now); | |
678 | set_cfs_rq_curr(cfs_rq, NULL); | |
679 | } | |
680 | ||
681 | static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) | |
682 | { | |
683 | struct rq *rq = rq_of(cfs_rq); | |
684 | struct sched_entity *next; | |
685 | u64 now = __rq_clock(rq); | |
686 | ||
687 | /* | |
688 | * Dequeue and enqueue the task to update its | |
689 | * position within the tree: | |
690 | */ | |
691 | dequeue_entity(cfs_rq, curr, 0, now); | |
692 | enqueue_entity(cfs_rq, curr, 0, now); | |
693 | ||
694 | /* | |
695 | * Reschedule if another task tops the current one. | |
696 | */ | |
697 | next = __pick_next_entity(cfs_rq); | |
698 | if (next == curr) | |
699 | return; | |
700 | ||
701 | __check_preempt_curr_fair(cfs_rq, next, curr, sysctl_sched_granularity); | |
702 | } | |
703 | ||
704 | /************************************************** | |
705 | * CFS operations on tasks: | |
706 | */ | |
707 | ||
708 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
709 | ||
710 | /* Walk up scheduling entities hierarchy */ | |
711 | #define for_each_sched_entity(se) \ | |
712 | for (; se; se = se->parent) | |
713 | ||
714 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) | |
715 | { | |
716 | return p->se.cfs_rq; | |
717 | } | |
718 | ||
719 | /* runqueue on which this entity is (to be) queued */ | |
720 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) | |
721 | { | |
722 | return se->cfs_rq; | |
723 | } | |
724 | ||
725 | /* runqueue "owned" by this group */ | |
726 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
727 | { | |
728 | return grp->my_q; | |
729 | } | |
730 | ||
731 | /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on | |
732 | * another cpu ('this_cpu') | |
733 | */ | |
734 | static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) | |
735 | { | |
736 | /* A later patch will take group into account */ | |
737 | return &cpu_rq(this_cpu)->cfs; | |
738 | } | |
739 | ||
740 | /* Iterate thr' all leaf cfs_rq's on a runqueue */ | |
741 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ | |
742 | list_for_each_entry(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) | |
743 | ||
744 | /* Do the two (enqueued) tasks belong to the same group ? */ | |
745 | static inline int is_same_group(struct task_struct *curr, struct task_struct *p) | |
746 | { | |
747 | if (curr->se.cfs_rq == p->se.cfs_rq) | |
748 | return 1; | |
749 | ||
750 | return 0; | |
751 | } | |
752 | ||
753 | #else /* CONFIG_FAIR_GROUP_SCHED */ | |
754 | ||
755 | #define for_each_sched_entity(se) \ | |
756 | for (; se; se = NULL) | |
757 | ||
758 | static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) | |
759 | { | |
760 | return &task_rq(p)->cfs; | |
761 | } | |
762 | ||
763 | static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) | |
764 | { | |
765 | struct task_struct *p = task_of(se); | |
766 | struct rq *rq = task_rq(p); | |
767 | ||
768 | return &rq->cfs; | |
769 | } | |
770 | ||
771 | /* runqueue "owned" by this group */ | |
772 | static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) | |
773 | { | |
774 | return NULL; | |
775 | } | |
776 | ||
777 | static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) | |
778 | { | |
779 | return &cpu_rq(this_cpu)->cfs; | |
780 | } | |
781 | ||
782 | #define for_each_leaf_cfs_rq(rq, cfs_rq) \ | |
783 | for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) | |
784 | ||
785 | static inline int is_same_group(struct task_struct *curr, struct task_struct *p) | |
786 | { | |
787 | return 1; | |
788 | } | |
789 | ||
790 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
791 | ||
792 | /* | |
793 | * The enqueue_task method is called before nr_running is | |
794 | * increased. Here we update the fair scheduling stats and | |
795 | * then put the task into the rbtree: | |
796 | */ | |
797 | static void | |
798 | enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup, u64 now) | |
799 | { | |
800 | struct cfs_rq *cfs_rq; | |
801 | struct sched_entity *se = &p->se; | |
802 | ||
803 | for_each_sched_entity(se) { | |
804 | if (se->on_rq) | |
805 | break; | |
806 | cfs_rq = cfs_rq_of(se); | |
807 | enqueue_entity(cfs_rq, se, wakeup, now); | |
808 | } | |
809 | } | |
810 | ||
811 | /* | |
812 | * The dequeue_task method is called before nr_running is | |
813 | * decreased. We remove the task from the rbtree and | |
814 | * update the fair scheduling stats: | |
815 | */ | |
816 | static void | |
817 | dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep, u64 now) | |
818 | { | |
819 | struct cfs_rq *cfs_rq; | |
820 | struct sched_entity *se = &p->se; | |
821 | ||
822 | for_each_sched_entity(se) { | |
823 | cfs_rq = cfs_rq_of(se); | |
824 | dequeue_entity(cfs_rq, se, sleep, now); | |
825 | /* Don't dequeue parent if it has other entities besides us */ | |
826 | if (cfs_rq->load.weight) | |
827 | break; | |
828 | } | |
829 | } | |
830 | ||
831 | /* | |
832 | * sched_yield() support is very simple - we dequeue and enqueue | |
833 | */ | |
834 | static void yield_task_fair(struct rq *rq, struct task_struct *p) | |
835 | { | |
836 | struct cfs_rq *cfs_rq = task_cfs_rq(p); | |
837 | u64 now = __rq_clock(rq); | |
838 | ||
839 | /* | |
840 | * Dequeue and enqueue the task to update its | |
841 | * position within the tree: | |
842 | */ | |
843 | dequeue_entity(cfs_rq, &p->se, 0, now); | |
844 | enqueue_entity(cfs_rq, &p->se, 0, now); | |
845 | } | |
846 | ||
847 | /* | |
848 | * Preempt the current task with a newly woken task if needed: | |
849 | */ | |
850 | static void check_preempt_curr_fair(struct rq *rq, struct task_struct *p) | |
851 | { | |
852 | struct task_struct *curr = rq->curr; | |
853 | struct cfs_rq *cfs_rq = task_cfs_rq(curr); | |
854 | unsigned long gran; | |
855 | ||
856 | if (unlikely(rt_prio(p->prio))) { | |
857 | update_curr(cfs_rq, rq_clock(rq)); | |
858 | resched_task(curr); | |
859 | return; | |
860 | } | |
861 | ||
862 | gran = sysctl_sched_wakeup_granularity; | |
863 | /* | |
864 | * Batch tasks prefer throughput over latency: | |
865 | */ | |
866 | if (unlikely(p->policy == SCHED_BATCH)) | |
867 | gran = sysctl_sched_batch_wakeup_granularity; | |
868 | ||
869 | if (is_same_group(curr, p)) | |
870 | __check_preempt_curr_fair(cfs_rq, &p->se, &curr->se, gran); | |
871 | } | |
872 | ||
873 | static struct task_struct *pick_next_task_fair(struct rq *rq, u64 now) | |
874 | { | |
875 | struct cfs_rq *cfs_rq = &rq->cfs; | |
876 | struct sched_entity *se; | |
877 | ||
878 | if (unlikely(!cfs_rq->nr_running)) | |
879 | return NULL; | |
880 | ||
881 | do { | |
882 | se = pick_next_entity(cfs_rq, now); | |
883 | cfs_rq = group_cfs_rq(se); | |
884 | } while (cfs_rq); | |
885 | ||
886 | return task_of(se); | |
887 | } | |
888 | ||
889 | /* | |
890 | * Account for a descheduled task: | |
891 | */ | |
892 | static void put_prev_task_fair(struct rq *rq, struct task_struct *prev, u64 now) | |
893 | { | |
894 | struct sched_entity *se = &prev->se; | |
895 | struct cfs_rq *cfs_rq; | |
896 | ||
897 | for_each_sched_entity(se) { | |
898 | cfs_rq = cfs_rq_of(se); | |
899 | put_prev_entity(cfs_rq, se, now); | |
900 | } | |
901 | } | |
902 | ||
903 | /************************************************** | |
904 | * Fair scheduling class load-balancing methods: | |
905 | */ | |
906 | ||
907 | /* | |
908 | * Load-balancing iterator. Note: while the runqueue stays locked | |
909 | * during the whole iteration, the current task might be | |
910 | * dequeued so the iterator has to be dequeue-safe. Here we | |
911 | * achieve that by always pre-iterating before returning | |
912 | * the current task: | |
913 | */ | |
914 | static inline struct task_struct * | |
915 | __load_balance_iterator(struct cfs_rq *cfs_rq, struct rb_node *curr) | |
916 | { | |
917 | struct task_struct *p; | |
918 | ||
919 | if (!curr) | |
920 | return NULL; | |
921 | ||
922 | p = rb_entry(curr, struct task_struct, se.run_node); | |
923 | cfs_rq->rb_load_balance_curr = rb_next(curr); | |
924 | ||
925 | return p; | |
926 | } | |
927 | ||
928 | static struct task_struct *load_balance_start_fair(void *arg) | |
929 | { | |
930 | struct cfs_rq *cfs_rq = arg; | |
931 | ||
932 | return __load_balance_iterator(cfs_rq, first_fair(cfs_rq)); | |
933 | } | |
934 | ||
935 | static struct task_struct *load_balance_next_fair(void *arg) | |
936 | { | |
937 | struct cfs_rq *cfs_rq = arg; | |
938 | ||
939 | return __load_balance_iterator(cfs_rq, cfs_rq->rb_load_balance_curr); | |
940 | } | |
941 | ||
942 | static int cfs_rq_best_prio(struct cfs_rq *cfs_rq) | |
943 | { | |
944 | struct sched_entity *curr; | |
945 | struct task_struct *p; | |
946 | ||
947 | if (!cfs_rq->nr_running) | |
948 | return MAX_PRIO; | |
949 | ||
950 | curr = __pick_next_entity(cfs_rq); | |
951 | p = task_of(curr); | |
952 | ||
953 | return p->prio; | |
954 | } | |
955 | ||
956 | static int | |
957 | load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, | |
958 | unsigned long max_nr_move, unsigned long max_load_move, | |
959 | struct sched_domain *sd, enum cpu_idle_type idle, | |
960 | int *all_pinned, unsigned long *total_load_moved) | |
961 | { | |
962 | struct cfs_rq *busy_cfs_rq; | |
963 | unsigned long load_moved, total_nr_moved = 0, nr_moved; | |
964 | long rem_load_move = max_load_move; | |
965 | struct rq_iterator cfs_rq_iterator; | |
966 | ||
967 | cfs_rq_iterator.start = load_balance_start_fair; | |
968 | cfs_rq_iterator.next = load_balance_next_fair; | |
969 | ||
970 | for_each_leaf_cfs_rq(busiest, busy_cfs_rq) { | |
971 | struct cfs_rq *this_cfs_rq; | |
972 | long imbalance; | |
973 | unsigned long maxload; | |
974 | int this_best_prio, best_prio, best_prio_seen = 0; | |
975 | ||
976 | this_cfs_rq = cpu_cfs_rq(busy_cfs_rq, this_cpu); | |
977 | ||
978 | imbalance = busy_cfs_rq->load.weight - | |
979 | this_cfs_rq->load.weight; | |
980 | /* Don't pull if this_cfs_rq has more load than busy_cfs_rq */ | |
981 | if (imbalance <= 0) | |
982 | continue; | |
983 | ||
984 | /* Don't pull more than imbalance/2 */ | |
985 | imbalance /= 2; | |
986 | maxload = min(rem_load_move, imbalance); | |
987 | ||
988 | this_best_prio = cfs_rq_best_prio(this_cfs_rq); | |
989 | best_prio = cfs_rq_best_prio(busy_cfs_rq); | |
990 | ||
991 | /* | |
992 | * Enable handling of the case where there is more than one task | |
993 | * with the best priority. If the current running task is one | |
994 | * of those with prio==best_prio we know it won't be moved | |
995 | * and therefore it's safe to override the skip (based on load) | |
996 | * of any task we find with that prio. | |
997 | */ | |
998 | if (cfs_rq_curr(busy_cfs_rq) == &busiest->curr->se) | |
999 | best_prio_seen = 1; | |
1000 | ||
1001 | /* pass busy_cfs_rq argument into | |
1002 | * load_balance_[start|next]_fair iterators | |
1003 | */ | |
1004 | cfs_rq_iterator.arg = busy_cfs_rq; | |
1005 | nr_moved = balance_tasks(this_rq, this_cpu, busiest, | |
1006 | max_nr_move, maxload, sd, idle, all_pinned, | |
1007 | &load_moved, this_best_prio, best_prio, | |
1008 | best_prio_seen, &cfs_rq_iterator); | |
1009 | ||
1010 | total_nr_moved += nr_moved; | |
1011 | max_nr_move -= nr_moved; | |
1012 | rem_load_move -= load_moved; | |
1013 | ||
1014 | if (max_nr_move <= 0 || rem_load_move <= 0) | |
1015 | break; | |
1016 | } | |
1017 | ||
1018 | *total_load_moved = max_load_move - rem_load_move; | |
1019 | ||
1020 | return total_nr_moved; | |
1021 | } | |
1022 | ||
1023 | /* | |
1024 | * scheduler tick hitting a task of our scheduling class: | |
1025 | */ | |
1026 | static void task_tick_fair(struct rq *rq, struct task_struct *curr) | |
1027 | { | |
1028 | struct cfs_rq *cfs_rq; | |
1029 | struct sched_entity *se = &curr->se; | |
1030 | ||
1031 | for_each_sched_entity(se) { | |
1032 | cfs_rq = cfs_rq_of(se); | |
1033 | entity_tick(cfs_rq, se); | |
1034 | } | |
1035 | } | |
1036 | ||
1037 | /* | |
1038 | * Share the fairness runtime between parent and child, thus the | |
1039 | * total amount of pressure for CPU stays equal - new tasks | |
1040 | * get a chance to run but frequent forkers are not allowed to | |
1041 | * monopolize the CPU. Note: the parent runqueue is locked, | |
1042 | * the child is not running yet. | |
1043 | */ | |
1044 | static void task_new_fair(struct rq *rq, struct task_struct *p) | |
1045 | { | |
1046 | struct cfs_rq *cfs_rq = task_cfs_rq(p); | |
1047 | struct sched_entity *se = &p->se; | |
1048 | u64 now = rq_clock(rq); | |
1049 | ||
1050 | sched_info_queued(p); | |
1051 | ||
1052 | update_stats_enqueue(cfs_rq, se, now); | |
1053 | /* | |
1054 | * Child runs first: we let it run before the parent | |
1055 | * until it reschedules once. We set up the key so that | |
1056 | * it will preempt the parent: | |
1057 | */ | |
1058 | p->se.fair_key = current->se.fair_key - | |
1059 | niced_granularity(&rq->curr->se, sysctl_sched_granularity) - 1; | |
1060 | /* | |
1061 | * The first wait is dominated by the child-runs-first logic, | |
1062 | * so do not credit it with that waiting time yet: | |
1063 | */ | |
1064 | if (sysctl_sched_features & SCHED_FEAT_SKIP_INITIAL) | |
1065 | p->se.wait_start_fair = 0; | |
1066 | ||
1067 | /* | |
1068 | * The statistical average of wait_runtime is about | |
1069 | * -granularity/2, so initialize the task with that: | |
1070 | */ | |
1071 | if (sysctl_sched_features & SCHED_FEAT_START_DEBIT) | |
1072 | p->se.wait_runtime = -(sysctl_sched_granularity / 2); | |
1073 | ||
1074 | __enqueue_entity(cfs_rq, se); | |
1075 | inc_nr_running(p, rq, now); | |
1076 | } | |
1077 | ||
1078 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
1079 | /* Account for a task changing its policy or group. | |
1080 | * | |
1081 | * This routine is mostly called to set cfs_rq->curr field when a task | |
1082 | * migrates between groups/classes. | |
1083 | */ | |
1084 | static void set_curr_task_fair(struct rq *rq) | |
1085 | { | |
1086 | struct task_struct *curr = rq->curr; | |
1087 | struct sched_entity *se = &curr->se; | |
1088 | u64 now = rq_clock(rq); | |
1089 | struct cfs_rq *cfs_rq; | |
1090 | ||
1091 | for_each_sched_entity(se) { | |
1092 | cfs_rq = cfs_rq_of(se); | |
1093 | set_next_entity(cfs_rq, se, now); | |
1094 | } | |
1095 | } | |
1096 | #else | |
1097 | static void set_curr_task_fair(struct rq *rq) | |
1098 | { | |
1099 | } | |
1100 | #endif | |
1101 | ||
1102 | /* | |
1103 | * All the scheduling class methods: | |
1104 | */ | |
1105 | struct sched_class fair_sched_class __read_mostly = { | |
1106 | .enqueue_task = enqueue_task_fair, | |
1107 | .dequeue_task = dequeue_task_fair, | |
1108 | .yield_task = yield_task_fair, | |
1109 | ||
1110 | .check_preempt_curr = check_preempt_curr_fair, | |
1111 | ||
1112 | .pick_next_task = pick_next_task_fair, | |
1113 | .put_prev_task = put_prev_task_fair, | |
1114 | ||
1115 | .load_balance = load_balance_fair, | |
1116 | ||
1117 | .set_curr_task = set_curr_task_fair, | |
1118 | .task_tick = task_tick_fair, | |
1119 | .task_new = task_new_fair, | |
1120 | }; | |
1121 | ||
1122 | #ifdef CONFIG_SCHED_DEBUG | |
1123 | void print_cfs_stats(struct seq_file *m, int cpu, u64 now) | |
1124 | { | |
1125 | struct rq *rq = cpu_rq(cpu); | |
1126 | struct cfs_rq *cfs_rq; | |
1127 | ||
1128 | for_each_leaf_cfs_rq(rq, cfs_rq) | |
1129 | print_cfs_rq(m, cpu, cfs_rq, now); | |
1130 | } | |
1131 | #endif |