sched_fair.c 40 KB

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  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. * Adaptive scheduling granularity, math enhancements by Peter Zijlstra
  20. * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
  21. */
  22. #include <linux/latencytop.h>
  23. /*
  24. * Targeted preemption latency for CPU-bound tasks:
  25. * (default: 20ms * (1 + ilog(ncpus)), units: nanoseconds)
  26. *
  27. * NOTE: this latency value is not the same as the concept of
  28. * 'timeslice length' - timeslices in CFS are of variable length
  29. * and have no persistent notion like in traditional, time-slice
  30. * based scheduling concepts.
  31. *
  32. * (to see the precise effective timeslice length of your workload,
  33. * run vmstat and monitor the context-switches (cs) field)
  34. */
  35. unsigned int sysctl_sched_latency = 20000000ULL;
  36. /*
  37. * Minimal preemption granularity for CPU-bound tasks:
  38. * (default: 4 msec * (1 + ilog(ncpus)), units: nanoseconds)
  39. */
  40. unsigned int sysctl_sched_min_granularity = 4000000ULL;
  41. /*
  42. * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
  43. */
  44. static unsigned int sched_nr_latency = 5;
  45. /*
  46. * After fork, child runs first. (default) If set to 0 then
  47. * parent will (try to) run first.
  48. */
  49. const_debug unsigned int sysctl_sched_child_runs_first = 1;
  50. /*
  51. * sys_sched_yield() compat mode
  52. *
  53. * This option switches the agressive yield implementation of the
  54. * old scheduler back on.
  55. */
  56. unsigned int __read_mostly sysctl_sched_compat_yield;
  57. /*
  58. * SCHED_OTHER wake-up granularity.
  59. * (default: 5 msec * (1 + ilog(ncpus)), units: nanoseconds)
  60. *
  61. * This option delays the preemption effects of decoupled workloads
  62. * and reduces their over-scheduling. Synchronous workloads will still
  63. * have immediate wakeup/sleep latencies.
  64. */
  65. unsigned int sysctl_sched_wakeup_granularity = 5000000UL;
  66. const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
  67. /**************************************************************
  68. * CFS operations on generic schedulable entities:
  69. */
  70. static inline struct task_struct *task_of(struct sched_entity *se)
  71. {
  72. return container_of(se, struct task_struct, se);
  73. }
  74. #ifdef CONFIG_FAIR_GROUP_SCHED
  75. /* cpu runqueue to which this cfs_rq is attached */
  76. static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
  77. {
  78. return cfs_rq->rq;
  79. }
  80. /* An entity is a task if it doesn't "own" a runqueue */
  81. #define entity_is_task(se) (!se->my_q)
  82. /* Walk up scheduling entities hierarchy */
  83. #define for_each_sched_entity(se) \
  84. for (; se; se = se->parent)
  85. static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
  86. {
  87. return p->se.cfs_rq;
  88. }
  89. /* runqueue on which this entity is (to be) queued */
  90. static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
  91. {
  92. return se->cfs_rq;
  93. }
  94. /* runqueue "owned" by this group */
  95. static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
  96. {
  97. return grp->my_q;
  98. }
  99. /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
  100. * another cpu ('this_cpu')
  101. */
  102. static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
  103. {
  104. return cfs_rq->tg->cfs_rq[this_cpu];
  105. }
  106. /* Iterate thr' all leaf cfs_rq's on a runqueue */
  107. #define for_each_leaf_cfs_rq(rq, cfs_rq) \
  108. list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
  109. /* Do the two (enqueued) entities belong to the same group ? */
  110. static inline int
  111. is_same_group(struct sched_entity *se, struct sched_entity *pse)
  112. {
  113. if (se->cfs_rq == pse->cfs_rq)
  114. return 1;
  115. return 0;
  116. }
  117. static inline struct sched_entity *parent_entity(struct sched_entity *se)
  118. {
  119. return se->parent;
  120. }
  121. #else /* CONFIG_FAIR_GROUP_SCHED */
  122. static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
  123. {
  124. return container_of(cfs_rq, struct rq, cfs);
  125. }
  126. #define entity_is_task(se) 1
  127. #define for_each_sched_entity(se) \
  128. for (; se; se = NULL)
  129. static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
  130. {
  131. return &task_rq(p)->cfs;
  132. }
  133. static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
  134. {
  135. struct task_struct *p = task_of(se);
  136. struct rq *rq = task_rq(p);
  137. return &rq->cfs;
  138. }
  139. /* runqueue "owned" by this group */
  140. static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
  141. {
  142. return NULL;
  143. }
  144. static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
  145. {
  146. return &cpu_rq(this_cpu)->cfs;
  147. }
  148. #define for_each_leaf_cfs_rq(rq, cfs_rq) \
  149. for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
  150. static inline int
  151. is_same_group(struct sched_entity *se, struct sched_entity *pse)
  152. {
  153. return 1;
  154. }
  155. static inline struct sched_entity *parent_entity(struct sched_entity *se)
  156. {
  157. return NULL;
  158. }
  159. #endif /* CONFIG_FAIR_GROUP_SCHED */
  160. /**************************************************************
  161. * Scheduling class tree data structure manipulation methods:
  162. */
  163. static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
  164. {
  165. s64 delta = (s64)(vruntime - min_vruntime);
  166. if (delta > 0)
  167. min_vruntime = vruntime;
  168. return min_vruntime;
  169. }
  170. static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
  171. {
  172. s64 delta = (s64)(vruntime - min_vruntime);
  173. if (delta < 0)
  174. min_vruntime = vruntime;
  175. return min_vruntime;
  176. }
  177. static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
  178. {
  179. return se->vruntime - cfs_rq->min_vruntime;
  180. }
  181. /*
  182. * Enqueue an entity into the rb-tree:
  183. */
  184. static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
  185. {
  186. struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
  187. struct rb_node *parent = NULL;
  188. struct sched_entity *entry;
  189. s64 key = entity_key(cfs_rq, se);
  190. int leftmost = 1;
  191. /*
  192. * Find the right place in the rbtree:
  193. */
  194. while (*link) {
  195. parent = *link;
  196. entry = rb_entry(parent, struct sched_entity, run_node);
  197. /*
  198. * We dont care about collisions. Nodes with
  199. * the same key stay together.
  200. */
  201. if (key < entity_key(cfs_rq, entry)) {
  202. link = &parent->rb_left;
  203. } else {
  204. link = &parent->rb_right;
  205. leftmost = 0;
  206. }
  207. }
  208. /*
  209. * Maintain a cache of leftmost tree entries (it is frequently
  210. * used):
  211. */
  212. if (leftmost) {
  213. cfs_rq->rb_leftmost = &se->run_node;
  214. /*
  215. * maintain cfs_rq->min_vruntime to be a monotonic increasing
  216. * value tracking the leftmost vruntime in the tree.
  217. */
  218. cfs_rq->min_vruntime =
  219. max_vruntime(cfs_rq->min_vruntime, se->vruntime);
  220. }
  221. rb_link_node(&se->run_node, parent, link);
  222. rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
  223. }
  224. static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
  225. {
  226. if (cfs_rq->rb_leftmost == &se->run_node) {
  227. struct rb_node *next_node;
  228. struct sched_entity *next;
  229. next_node = rb_next(&se->run_node);
  230. cfs_rq->rb_leftmost = next_node;
  231. if (next_node) {
  232. next = rb_entry(next_node,
  233. struct sched_entity, run_node);
  234. cfs_rq->min_vruntime =
  235. max_vruntime(cfs_rq->min_vruntime,
  236. next->vruntime);
  237. }
  238. }
  239. if (cfs_rq->next == se)
  240. cfs_rq->next = NULL;
  241. rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
  242. }
  243. static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
  244. {
  245. return cfs_rq->rb_leftmost;
  246. }
  247. static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
  248. {
  249. return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node);
  250. }
  251. static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
  252. {
  253. struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
  254. if (!last)
  255. return NULL;
  256. return rb_entry(last, struct sched_entity, run_node);
  257. }
  258. /**************************************************************
  259. * Scheduling class statistics methods:
  260. */
  261. #ifdef CONFIG_SCHED_DEBUG
  262. int sched_nr_latency_handler(struct ctl_table *table, int write,
  263. struct file *filp, void __user *buffer, size_t *lenp,
  264. loff_t *ppos)
  265. {
  266. int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
  267. if (ret || !write)
  268. return ret;
  269. sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
  270. sysctl_sched_min_granularity);
  271. return 0;
  272. }
  273. #endif
  274. /*
  275. * delta *= w / rw
  276. */
  277. static inline unsigned long
  278. calc_delta_weight(unsigned long delta, struct sched_entity *se)
  279. {
  280. for_each_sched_entity(se) {
  281. delta = calc_delta_mine(delta,
  282. se->load.weight, &cfs_rq_of(se)->load);
  283. }
  284. return delta;
  285. }
  286. /*
  287. * delta *= rw / w
  288. */
  289. static inline unsigned long
  290. calc_delta_fair(unsigned long delta, struct sched_entity *se)
  291. {
  292. for_each_sched_entity(se) {
  293. delta = calc_delta_mine(delta,
  294. cfs_rq_of(se)->load.weight, &se->load);
  295. }
  296. return delta;
  297. }
  298. /*
  299. * The idea is to set a period in which each task runs once.
  300. *
  301. * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
  302. * this period because otherwise the slices get too small.
  303. *
  304. * p = (nr <= nl) ? l : l*nr/nl
  305. */
  306. static u64 __sched_period(unsigned long nr_running)
  307. {
  308. u64 period = sysctl_sched_latency;
  309. unsigned long nr_latency = sched_nr_latency;
  310. if (unlikely(nr_running > nr_latency)) {
  311. period = sysctl_sched_min_granularity;
  312. period *= nr_running;
  313. }
  314. return period;
  315. }
  316. /*
  317. * We calculate the wall-time slice from the period by taking a part
  318. * proportional to the weight.
  319. *
  320. * s = p*w/rw
  321. */
  322. static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
  323. {
  324. return calc_delta_weight(__sched_period(cfs_rq->nr_running), se);
  325. }
  326. /*
  327. * We calculate the vruntime slice of a to be inserted task
  328. *
  329. * vs = s*rw/w = p
  330. */
  331. static u64 sched_vslice_add(struct cfs_rq *cfs_rq, struct sched_entity *se)
  332. {
  333. unsigned long nr_running = cfs_rq->nr_running;
  334. if (!se->on_rq)
  335. nr_running++;
  336. return __sched_period(nr_running);
  337. }
  338. /*
  339. * The goal of calc_delta_asym() is to be asymmetrically around NICE_0_LOAD, in
  340. * that it favours >=0 over <0.
  341. *
  342. * -20 |
  343. * |
  344. * 0 --------+-------
  345. * .'
  346. * 19 .'
  347. *
  348. */
  349. static unsigned long
  350. calc_delta_asym(unsigned long delta, struct sched_entity *se)
  351. {
  352. struct load_weight lw = {
  353. .weight = NICE_0_LOAD,
  354. .inv_weight = 1UL << (WMULT_SHIFT-NICE_0_SHIFT)
  355. };
  356. for_each_sched_entity(se) {
  357. struct load_weight *se_lw = &se->load;
  358. unsigned long rw = cfs_rq_of(se)->load.weight;
  359. #ifdef CONFIG_FAIR_SCHED_GROUP
  360. struct cfs_rq *cfs_rq = se->my_q;
  361. struct task_group *tg = NULL
  362. if (cfs_rq)
  363. tg = cfs_rq->tg;
  364. if (tg && tg->shares < NICE_0_LOAD) {
  365. /*
  366. * scale shares to what it would have been had
  367. * tg->weight been NICE_0_LOAD:
  368. *
  369. * weight = 1024 * shares / tg->weight
  370. */
  371. lw.weight *= se->load.weight;
  372. lw.weight /= tg->shares;
  373. lw.inv_weight = 0;
  374. se_lw = &lw;
  375. rw += lw.weight - se->load.weight;
  376. } else
  377. #endif
  378. if (se->load.weight < NICE_0_LOAD) {
  379. se_lw = &lw;
  380. rw += NICE_0_LOAD - se->load.weight;
  381. }
  382. delta = calc_delta_mine(delta, rw, se_lw);
  383. }
  384. return delta;
  385. }
  386. /*
  387. * Update the current task's runtime statistics. Skip current tasks that
  388. * are not in our scheduling class.
  389. */
  390. static inline void
  391. __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
  392. unsigned long delta_exec)
  393. {
  394. unsigned long delta_exec_weighted;
  395. schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
  396. curr->sum_exec_runtime += delta_exec;
  397. schedstat_add(cfs_rq, exec_clock, delta_exec);
  398. delta_exec_weighted = calc_delta_fair(delta_exec, curr);
  399. curr->vruntime += delta_exec_weighted;
  400. }
  401. static void update_curr(struct cfs_rq *cfs_rq)
  402. {
  403. struct sched_entity *curr = cfs_rq->curr;
  404. u64 now = rq_of(cfs_rq)->clock;
  405. unsigned long delta_exec;
  406. if (unlikely(!curr))
  407. return;
  408. /*
  409. * Get the amount of time the current task was running
  410. * since the last time we changed load (this cannot
  411. * overflow on 32 bits):
  412. */
  413. delta_exec = (unsigned long)(now - curr->exec_start);
  414. __update_curr(cfs_rq, curr, delta_exec);
  415. curr->exec_start = now;
  416. if (entity_is_task(curr)) {
  417. struct task_struct *curtask = task_of(curr);
  418. cpuacct_charge(curtask, delta_exec);
  419. }
  420. }
  421. static inline void
  422. update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
  423. {
  424. schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
  425. }
  426. /*
  427. * Task is being enqueued - update stats:
  428. */
  429. static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
  430. {
  431. /*
  432. * Are we enqueueing a waiting task? (for current tasks
  433. * a dequeue/enqueue event is a NOP)
  434. */
  435. if (se != cfs_rq->curr)
  436. update_stats_wait_start(cfs_rq, se);
  437. }
  438. static void
  439. update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
  440. {
  441. schedstat_set(se->wait_max, max(se->wait_max,
  442. rq_of(cfs_rq)->clock - se->wait_start));
  443. schedstat_set(se->wait_count, se->wait_count + 1);
  444. schedstat_set(se->wait_sum, se->wait_sum +
  445. rq_of(cfs_rq)->clock - se->wait_start);
  446. schedstat_set(se->wait_start, 0);
  447. }
  448. static inline void
  449. update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
  450. {
  451. /*
  452. * Mark the end of the wait period if dequeueing a
  453. * waiting task:
  454. */
  455. if (se != cfs_rq->curr)
  456. update_stats_wait_end(cfs_rq, se);
  457. }
  458. /*
  459. * We are picking a new current task - update its stats:
  460. */
  461. static inline void
  462. update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
  463. {
  464. /*
  465. * We are starting a new run period:
  466. */
  467. se->exec_start = rq_of(cfs_rq)->clock;
  468. }
  469. /**************************************************
  470. * Scheduling class queueing methods:
  471. */
  472. #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
  473. static void
  474. add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
  475. {
  476. cfs_rq->task_weight += weight;
  477. }
  478. #else
  479. static inline void
  480. add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
  481. {
  482. }
  483. #endif
  484. static void
  485. account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
  486. {
  487. update_load_add(&cfs_rq->load, se->load.weight);
  488. if (!parent_entity(se))
  489. inc_cpu_load(rq_of(cfs_rq), se->load.weight);
  490. if (entity_is_task(se))
  491. add_cfs_task_weight(cfs_rq, se->load.weight);
  492. cfs_rq->nr_running++;
  493. se->on_rq = 1;
  494. list_add(&se->group_node, &cfs_rq->tasks);
  495. }
  496. static void
  497. account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
  498. {
  499. update_load_sub(&cfs_rq->load, se->load.weight);
  500. if (!parent_entity(se))
  501. dec_cpu_load(rq_of(cfs_rq), se->load.weight);
  502. if (entity_is_task(se))
  503. add_cfs_task_weight(cfs_rq, -se->load.weight);
  504. cfs_rq->nr_running--;
  505. se->on_rq = 0;
  506. list_del_init(&se->group_node);
  507. }
  508. static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
  509. {
  510. #ifdef CONFIG_SCHEDSTATS
  511. if (se->sleep_start) {
  512. u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
  513. struct task_struct *tsk = task_of(se);
  514. if ((s64)delta < 0)
  515. delta = 0;
  516. if (unlikely(delta > se->sleep_max))
  517. se->sleep_max = delta;
  518. se->sleep_start = 0;
  519. se->sum_sleep_runtime += delta;
  520. account_scheduler_latency(tsk, delta >> 10, 1);
  521. }
  522. if (se->block_start) {
  523. u64 delta = rq_of(cfs_rq)->clock - se->block_start;
  524. struct task_struct *tsk = task_of(se);
  525. if ((s64)delta < 0)
  526. delta = 0;
  527. if (unlikely(delta > se->block_max))
  528. se->block_max = delta;
  529. se->block_start = 0;
  530. se->sum_sleep_runtime += delta;
  531. /*
  532. * Blocking time is in units of nanosecs, so shift by 20 to
  533. * get a milliseconds-range estimation of the amount of
  534. * time that the task spent sleeping:
  535. */
  536. if (unlikely(prof_on == SLEEP_PROFILING)) {
  537. profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
  538. delta >> 20);
  539. }
  540. account_scheduler_latency(tsk, delta >> 10, 0);
  541. }
  542. #endif
  543. }
  544. static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
  545. {
  546. #ifdef CONFIG_SCHED_DEBUG
  547. s64 d = se->vruntime - cfs_rq->min_vruntime;
  548. if (d < 0)
  549. d = -d;
  550. if (d > 3*sysctl_sched_latency)
  551. schedstat_inc(cfs_rq, nr_spread_over);
  552. #endif
  553. }
  554. static void
  555. place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
  556. {
  557. u64 vruntime;
  558. if (first_fair(cfs_rq)) {
  559. vruntime = min_vruntime(cfs_rq->min_vruntime,
  560. __pick_next_entity(cfs_rq)->vruntime);
  561. } else
  562. vruntime = cfs_rq->min_vruntime;
  563. /*
  564. * The 'current' period is already promised to the current tasks,
  565. * however the extra weight of the new task will slow them down a
  566. * little, place the new task so that it fits in the slot that
  567. * stays open at the end.
  568. */
  569. if (initial && sched_feat(START_DEBIT))
  570. vruntime += sched_vslice_add(cfs_rq, se);
  571. if (!initial) {
  572. /* sleeps upto a single latency don't count. */
  573. if (sched_feat(NEW_FAIR_SLEEPERS)) {
  574. unsigned long thresh = sysctl_sched_latency;
  575. /*
  576. * convert the sleeper threshold into virtual time
  577. */
  578. if (sched_feat(NORMALIZED_SLEEPER))
  579. thresh = calc_delta_fair(thresh, se);
  580. vruntime -= thresh;
  581. }
  582. /* ensure we never gain time by being placed backwards. */
  583. vruntime = max_vruntime(se->vruntime, vruntime);
  584. }
  585. se->vruntime = vruntime;
  586. }
  587. static void
  588. enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
  589. {
  590. /*
  591. * Update run-time statistics of the 'current'.
  592. */
  593. update_curr(cfs_rq);
  594. account_entity_enqueue(cfs_rq, se);
  595. if (wakeup) {
  596. place_entity(cfs_rq, se, 0);
  597. enqueue_sleeper(cfs_rq, se);
  598. }
  599. update_stats_enqueue(cfs_rq, se);
  600. check_spread(cfs_rq, se);
  601. if (se != cfs_rq->curr)
  602. __enqueue_entity(cfs_rq, se);
  603. }
  604. static void
  605. dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
  606. {
  607. /*
  608. * Update run-time statistics of the 'current'.
  609. */
  610. update_curr(cfs_rq);
  611. update_stats_dequeue(cfs_rq, se);
  612. if (sleep) {
  613. #ifdef CONFIG_SCHEDSTATS
  614. if (entity_is_task(se)) {
  615. struct task_struct *tsk = task_of(se);
  616. if (tsk->state & TASK_INTERRUPTIBLE)
  617. se->sleep_start = rq_of(cfs_rq)->clock;
  618. if (tsk->state & TASK_UNINTERRUPTIBLE)
  619. se->block_start = rq_of(cfs_rq)->clock;
  620. }
  621. #endif
  622. }
  623. if (se != cfs_rq->curr)
  624. __dequeue_entity(cfs_rq, se);
  625. account_entity_dequeue(cfs_rq, se);
  626. }
  627. /*
  628. * Preempt the current task with a newly woken task if needed:
  629. */
  630. static void
  631. check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
  632. {
  633. unsigned long ideal_runtime, delta_exec;
  634. ideal_runtime = sched_slice(cfs_rq, curr);
  635. delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
  636. if (delta_exec > ideal_runtime)
  637. resched_task(rq_of(cfs_rq)->curr);
  638. }
  639. static void
  640. set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
  641. {
  642. /* 'current' is not kept within the tree. */
  643. if (se->on_rq) {
  644. /*
  645. * Any task has to be enqueued before it get to execute on
  646. * a CPU. So account for the time it spent waiting on the
  647. * runqueue.
  648. */
  649. update_stats_wait_end(cfs_rq, se);
  650. __dequeue_entity(cfs_rq, se);
  651. }
  652. update_stats_curr_start(cfs_rq, se);
  653. cfs_rq->curr = se;
  654. #ifdef CONFIG_SCHEDSTATS
  655. /*
  656. * Track our maximum slice length, if the CPU's load is at
  657. * least twice that of our own weight (i.e. dont track it
  658. * when there are only lesser-weight tasks around):
  659. */
  660. if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
  661. se->slice_max = max(se->slice_max,
  662. se->sum_exec_runtime - se->prev_sum_exec_runtime);
  663. }
  664. #endif
  665. se->prev_sum_exec_runtime = se->sum_exec_runtime;
  666. }
  667. static struct sched_entity *
  668. pick_next(struct cfs_rq *cfs_rq, struct sched_entity *se)
  669. {
  670. struct rq *rq = rq_of(cfs_rq);
  671. u64 pair_slice = rq->clock - cfs_rq->pair_start;
  672. if (!cfs_rq->next || pair_slice > sched_slice(cfs_rq, cfs_rq->next)) {
  673. cfs_rq->pair_start = rq->clock;
  674. return se;
  675. }
  676. return cfs_rq->next;
  677. }
  678. static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
  679. {
  680. struct sched_entity *se = NULL;
  681. if (first_fair(cfs_rq)) {
  682. se = __pick_next_entity(cfs_rq);
  683. se = pick_next(cfs_rq, se);
  684. set_next_entity(cfs_rq, se);
  685. }
  686. return se;
  687. }
  688. static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
  689. {
  690. /*
  691. * If still on the runqueue then deactivate_task()
  692. * was not called and update_curr() has to be done:
  693. */
  694. if (prev->on_rq)
  695. update_curr(cfs_rq);
  696. check_spread(cfs_rq, prev);
  697. if (prev->on_rq) {
  698. update_stats_wait_start(cfs_rq, prev);
  699. /* Put 'current' back into the tree. */
  700. __enqueue_entity(cfs_rq, prev);
  701. }
  702. cfs_rq->curr = NULL;
  703. }
  704. static void
  705. entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
  706. {
  707. /*
  708. * Update run-time statistics of the 'current'.
  709. */
  710. update_curr(cfs_rq);
  711. #ifdef CONFIG_SCHED_HRTICK
  712. /*
  713. * queued ticks are scheduled to match the slice, so don't bother
  714. * validating it and just reschedule.
  715. */
  716. if (queued) {
  717. resched_task(rq_of(cfs_rq)->curr);
  718. return;
  719. }
  720. /*
  721. * don't let the period tick interfere with the hrtick preemption
  722. */
  723. if (!sched_feat(DOUBLE_TICK) &&
  724. hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
  725. return;
  726. #endif
  727. if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
  728. check_preempt_tick(cfs_rq, curr);
  729. }
  730. /**************************************************
  731. * CFS operations on tasks:
  732. */
  733. #ifdef CONFIG_SCHED_HRTICK
  734. static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
  735. {
  736. int requeue = rq->curr == p;
  737. struct sched_entity *se = &p->se;
  738. struct cfs_rq *cfs_rq = cfs_rq_of(se);
  739. WARN_ON(task_rq(p) != rq);
  740. if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) {
  741. u64 slice = sched_slice(cfs_rq, se);
  742. u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
  743. s64 delta = slice - ran;
  744. if (delta < 0) {
  745. if (rq->curr == p)
  746. resched_task(p);
  747. return;
  748. }
  749. /*
  750. * Don't schedule slices shorter than 10000ns, that just
  751. * doesn't make sense. Rely on vruntime for fairness.
  752. */
  753. if (!requeue)
  754. delta = max(10000LL, delta);
  755. hrtick_start(rq, delta, requeue);
  756. }
  757. }
  758. #else /* !CONFIG_SCHED_HRTICK */
  759. static inline void
  760. hrtick_start_fair(struct rq *rq, struct task_struct *p)
  761. {
  762. }
  763. #endif
  764. /*
  765. * The enqueue_task method is called before nr_running is
  766. * increased. Here we update the fair scheduling stats and
  767. * then put the task into the rbtree:
  768. */
  769. static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
  770. {
  771. struct cfs_rq *cfs_rq;
  772. struct sched_entity *se = &p->se;
  773. for_each_sched_entity(se) {
  774. if (se->on_rq)
  775. break;
  776. cfs_rq = cfs_rq_of(se);
  777. enqueue_entity(cfs_rq, se, wakeup);
  778. wakeup = 1;
  779. }
  780. hrtick_start_fair(rq, rq->curr);
  781. }
  782. /*
  783. * The dequeue_task method is called before nr_running is
  784. * decreased. We remove the task from the rbtree and
  785. * update the fair scheduling stats:
  786. */
  787. static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
  788. {
  789. struct cfs_rq *cfs_rq;
  790. struct sched_entity *se = &p->se;
  791. for_each_sched_entity(se) {
  792. cfs_rq = cfs_rq_of(se);
  793. dequeue_entity(cfs_rq, se, sleep);
  794. /* Don't dequeue parent if it has other entities besides us */
  795. if (cfs_rq->load.weight)
  796. break;
  797. sleep = 1;
  798. }
  799. hrtick_start_fair(rq, rq->curr);
  800. }
  801. /*
  802. * sched_yield() support is very simple - we dequeue and enqueue.
  803. *
  804. * If compat_yield is turned on then we requeue to the end of the tree.
  805. */
  806. static void yield_task_fair(struct rq *rq)
  807. {
  808. struct task_struct *curr = rq->curr;
  809. struct cfs_rq *cfs_rq = task_cfs_rq(curr);
  810. struct sched_entity *rightmost, *se = &curr->se;
  811. /*
  812. * Are we the only task in the tree?
  813. */
  814. if (unlikely(cfs_rq->nr_running == 1))
  815. return;
  816. if (likely(!sysctl_sched_compat_yield) && curr->policy != SCHED_BATCH) {
  817. update_rq_clock(rq);
  818. /*
  819. * Update run-time statistics of the 'current'.
  820. */
  821. update_curr(cfs_rq);
  822. return;
  823. }
  824. /*
  825. * Find the rightmost entry in the rbtree:
  826. */
  827. rightmost = __pick_last_entity(cfs_rq);
  828. /*
  829. * Already in the rightmost position?
  830. */
  831. if (unlikely(!rightmost || rightmost->vruntime < se->vruntime))
  832. return;
  833. /*
  834. * Minimally necessary key value to be last in the tree:
  835. * Upon rescheduling, sched_class::put_prev_task() will place
  836. * 'current' within the tree based on its new key value.
  837. */
  838. se->vruntime = rightmost->vruntime + 1;
  839. }
  840. /*
  841. * wake_idle() will wake a task on an idle cpu if task->cpu is
  842. * not idle and an idle cpu is available. The span of cpus to
  843. * search starts with cpus closest then further out as needed,
  844. * so we always favor a closer, idle cpu.
  845. *
  846. * Returns the CPU we should wake onto.
  847. */
  848. #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
  849. static int wake_idle(int cpu, struct task_struct *p)
  850. {
  851. cpumask_t tmp;
  852. struct sched_domain *sd;
  853. int i;
  854. /*
  855. * If it is idle, then it is the best cpu to run this task.
  856. *
  857. * This cpu is also the best, if it has more than one task already.
  858. * Siblings must be also busy(in most cases) as they didn't already
  859. * pickup the extra load from this cpu and hence we need not check
  860. * sibling runqueue info. This will avoid the checks and cache miss
  861. * penalities associated with that.
  862. */
  863. if (idle_cpu(cpu) || cpu_rq(cpu)->cfs.nr_running > 1)
  864. return cpu;
  865. for_each_domain(cpu, sd) {
  866. if ((sd->flags & SD_WAKE_IDLE)
  867. || ((sd->flags & SD_WAKE_IDLE_FAR)
  868. && !task_hot(p, task_rq(p)->clock, sd))) {
  869. cpus_and(tmp, sd->span, p->cpus_allowed);
  870. for_each_cpu_mask(i, tmp) {
  871. if (idle_cpu(i)) {
  872. if (i != task_cpu(p)) {
  873. schedstat_inc(p,
  874. se.nr_wakeups_idle);
  875. }
  876. return i;
  877. }
  878. }
  879. } else {
  880. break;
  881. }
  882. }
  883. return cpu;
  884. }
  885. #else /* !ARCH_HAS_SCHED_WAKE_IDLE*/
  886. static inline int wake_idle(int cpu, struct task_struct *p)
  887. {
  888. return cpu;
  889. }
  890. #endif
  891. #ifdef CONFIG_SMP
  892. static const struct sched_class fair_sched_class;
  893. #ifdef CONFIG_FAIR_GROUP_SCHED
  894. /*
  895. * effective_load() calculates the load change as seen from the root_task_group
  896. *
  897. * Adding load to a group doesn't make a group heavier, but can cause movement
  898. * of group shares between cpus. Assuming the shares were perfectly aligned one
  899. * can calculate the shift in shares.
  900. *
  901. * The problem is that perfectly aligning the shares is rather expensive, hence
  902. * we try to avoid doing that too often - see update_shares(), which ratelimits
  903. * this change.
  904. *
  905. * We compensate this by not only taking the current delta into account, but
  906. * also considering the delta between when the shares were last adjusted and
  907. * now.
  908. *
  909. * We still saw a performance dip, some tracing learned us that between
  910. * cgroup:/ and cgroup:/foo balancing the number of affine wakeups increased
  911. * significantly. Therefore try to bias the error in direction of failing
  912. * the affine wakeup.
  913. *
  914. */
  915. static long effective_load(struct task_group *tg, int cpu,
  916. long wl, long wg)
  917. {
  918. struct sched_entity *se = tg->se[cpu];
  919. long more_w;
  920. if (!tg->parent)
  921. return wl;
  922. /*
  923. * By not taking the decrease of shares on the other cpu into
  924. * account our error leans towards reducing the affine wakeups.
  925. */
  926. if (!wl && sched_feat(ASYM_EFF_LOAD))
  927. return wl;
  928. /*
  929. * Instead of using this increment, also add the difference
  930. * between when the shares were last updated and now.
  931. */
  932. more_w = se->my_q->load.weight - se->my_q->rq_weight;
  933. wl += more_w;
  934. wg += more_w;
  935. for_each_sched_entity(se) {
  936. #define D(n) (likely(n) ? (n) : 1)
  937. long S, rw, s, a, b;
  938. S = se->my_q->tg->shares;
  939. s = se->my_q->shares;
  940. rw = se->my_q->rq_weight;
  941. a = S*(rw + wl);
  942. b = S*rw + s*wg;
  943. wl = s*(a-b)/D(b);
  944. /*
  945. * Assume the group is already running and will
  946. * thus already be accounted for in the weight.
  947. *
  948. * That is, moving shares between CPUs, does not
  949. * alter the group weight.
  950. */
  951. wg = 0;
  952. #undef D
  953. }
  954. return wl;
  955. }
  956. #else
  957. static inline unsigned long effective_load(struct task_group *tg, int cpu,
  958. unsigned long wl, unsigned long wg)
  959. {
  960. return wl;
  961. }
  962. #endif
  963. static int
  964. wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
  965. struct task_struct *p, int prev_cpu, int this_cpu, int sync,
  966. int idx, unsigned long load, unsigned long this_load,
  967. unsigned int imbalance)
  968. {
  969. struct task_struct *curr = this_rq->curr;
  970. struct task_group *tg;
  971. unsigned long tl = this_load;
  972. unsigned long tl_per_task;
  973. unsigned long weight;
  974. int balanced;
  975. if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
  976. return 0;
  977. /*
  978. * If sync wakeup then subtract the (maximum possible)
  979. * effect of the currently running task from the load
  980. * of the current CPU:
  981. */
  982. if (sync) {
  983. tg = task_group(current);
  984. weight = current->se.load.weight;
  985. tl += effective_load(tg, this_cpu, -weight, -weight);
  986. load += effective_load(tg, prev_cpu, 0, -weight);
  987. }
  988. tg = task_group(p);
  989. weight = p->se.load.weight;
  990. balanced = 100*(tl + effective_load(tg, this_cpu, weight, weight)) <=
  991. imbalance*(load + effective_load(tg, prev_cpu, 0, weight));
  992. /*
  993. * If the currently running task will sleep within
  994. * a reasonable amount of time then attract this newly
  995. * woken task:
  996. */
  997. if (sync && balanced) {
  998. if (curr->se.avg_overlap < sysctl_sched_migration_cost &&
  999. p->se.avg_overlap < sysctl_sched_migration_cost)
  1000. return 1;
  1001. }
  1002. schedstat_inc(p, se.nr_wakeups_affine_attempts);
  1003. tl_per_task = cpu_avg_load_per_task(this_cpu);
  1004. if ((tl <= load && tl + target_load(prev_cpu, idx) <= tl_per_task) ||
  1005. balanced) {
  1006. /*
  1007. * This domain has SD_WAKE_AFFINE and
  1008. * p is cache cold in this domain, and
  1009. * there is no bad imbalance.
  1010. */
  1011. schedstat_inc(this_sd, ttwu_move_affine);
  1012. schedstat_inc(p, se.nr_wakeups_affine);
  1013. return 1;
  1014. }
  1015. return 0;
  1016. }
  1017. static int select_task_rq_fair(struct task_struct *p, int sync)
  1018. {
  1019. struct sched_domain *sd, *this_sd = NULL;
  1020. int prev_cpu, this_cpu, new_cpu;
  1021. unsigned long load, this_load;
  1022. struct rq *rq, *this_rq;
  1023. unsigned int imbalance;
  1024. int idx;
  1025. prev_cpu = task_cpu(p);
  1026. rq = task_rq(p);
  1027. this_cpu = smp_processor_id();
  1028. this_rq = cpu_rq(this_cpu);
  1029. new_cpu = prev_cpu;
  1030. /*
  1031. * 'this_sd' is the first domain that both
  1032. * this_cpu and prev_cpu are present in:
  1033. */
  1034. for_each_domain(this_cpu, sd) {
  1035. if (cpu_isset(prev_cpu, sd->span)) {
  1036. this_sd = sd;
  1037. break;
  1038. }
  1039. }
  1040. if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
  1041. goto out;
  1042. /*
  1043. * Check for affine wakeup and passive balancing possibilities.
  1044. */
  1045. if (!this_sd)
  1046. goto out;
  1047. idx = this_sd->wake_idx;
  1048. imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
  1049. load = source_load(prev_cpu, idx);
  1050. this_load = target_load(this_cpu, idx);
  1051. if (wake_affine(rq, this_sd, this_rq, p, prev_cpu, this_cpu, sync, idx,
  1052. load, this_load, imbalance))
  1053. return this_cpu;
  1054. if (prev_cpu == this_cpu)
  1055. goto out;
  1056. /*
  1057. * Start passive balancing when half the imbalance_pct
  1058. * limit is reached.
  1059. */
  1060. if (this_sd->flags & SD_WAKE_BALANCE) {
  1061. if (imbalance*this_load <= 100*load) {
  1062. schedstat_inc(this_sd, ttwu_move_balance);
  1063. schedstat_inc(p, se.nr_wakeups_passive);
  1064. return this_cpu;
  1065. }
  1066. }
  1067. out:
  1068. return wake_idle(new_cpu, p);
  1069. }
  1070. #endif /* CONFIG_SMP */
  1071. static unsigned long wakeup_gran(struct sched_entity *se)
  1072. {
  1073. unsigned long gran = sysctl_sched_wakeup_granularity;
  1074. /*
  1075. * More easily preempt - nice tasks, while not making it harder for
  1076. * + nice tasks.
  1077. */
  1078. if (sched_feat(ASYM_GRAN))
  1079. gran = calc_delta_asym(sysctl_sched_wakeup_granularity, se);
  1080. else
  1081. gran = calc_delta_fair(sysctl_sched_wakeup_granularity, se);
  1082. return gran;
  1083. }
  1084. /*
  1085. * Should 'se' preempt 'curr'.
  1086. *
  1087. * |s1
  1088. * |s2
  1089. * |s3
  1090. * g
  1091. * |<--->|c
  1092. *
  1093. * w(c, s1) = -1
  1094. * w(c, s2) = 0
  1095. * w(c, s3) = 1
  1096. *
  1097. */
  1098. static int
  1099. wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
  1100. {
  1101. s64 gran, vdiff = curr->vruntime - se->vruntime;
  1102. if (vdiff < 0)
  1103. return -1;
  1104. gran = wakeup_gran(curr);
  1105. if (vdiff > gran)
  1106. return 1;
  1107. return 0;
  1108. }
  1109. /* return depth at which a sched entity is present in the hierarchy */
  1110. static inline int depth_se(struct sched_entity *se)
  1111. {
  1112. int depth = 0;
  1113. for_each_sched_entity(se)
  1114. depth++;
  1115. return depth;
  1116. }
  1117. /*
  1118. * Preempt the current task with a newly woken task if needed:
  1119. */
  1120. static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
  1121. {
  1122. struct task_struct *curr = rq->curr;
  1123. struct cfs_rq *cfs_rq = task_cfs_rq(curr);
  1124. struct sched_entity *se = &curr->se, *pse = &p->se;
  1125. int se_depth, pse_depth;
  1126. if (unlikely(rt_prio(p->prio))) {
  1127. update_rq_clock(rq);
  1128. update_curr(cfs_rq);
  1129. resched_task(curr);
  1130. return;
  1131. }
  1132. if (unlikely(se == pse))
  1133. return;
  1134. cfs_rq_of(pse)->next = pse;
  1135. /*
  1136. * Batch tasks do not preempt (their preemption is driven by
  1137. * the tick):
  1138. */
  1139. if (unlikely(p->policy == SCHED_BATCH))
  1140. return;
  1141. if (!sched_feat(WAKEUP_PREEMPT))
  1142. return;
  1143. /*
  1144. * preemption test can be made between sibling entities who are in the
  1145. * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
  1146. * both tasks until we find their ancestors who are siblings of common
  1147. * parent.
  1148. */
  1149. /* First walk up until both entities are at same depth */
  1150. se_depth = depth_se(se);
  1151. pse_depth = depth_se(pse);
  1152. while (se_depth > pse_depth) {
  1153. se_depth--;
  1154. se = parent_entity(se);
  1155. }
  1156. while (pse_depth > se_depth) {
  1157. pse_depth--;
  1158. pse = parent_entity(pse);
  1159. }
  1160. while (!is_same_group(se, pse)) {
  1161. se = parent_entity(se);
  1162. pse = parent_entity(pse);
  1163. }
  1164. if (wakeup_preempt_entity(se, pse) == 1)
  1165. resched_task(curr);
  1166. }
  1167. static struct task_struct *pick_next_task_fair(struct rq *rq)
  1168. {
  1169. struct task_struct *p;
  1170. struct cfs_rq *cfs_rq = &rq->cfs;
  1171. struct sched_entity *se;
  1172. if (unlikely(!cfs_rq->nr_running))
  1173. return NULL;
  1174. do {
  1175. se = pick_next_entity(cfs_rq);
  1176. cfs_rq = group_cfs_rq(se);
  1177. } while (cfs_rq);
  1178. p = task_of(se);
  1179. hrtick_start_fair(rq, p);
  1180. return p;
  1181. }
  1182. /*
  1183. * Account for a descheduled task:
  1184. */
  1185. static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
  1186. {
  1187. struct sched_entity *se = &prev->se;
  1188. struct cfs_rq *cfs_rq;
  1189. for_each_sched_entity(se) {
  1190. cfs_rq = cfs_rq_of(se);
  1191. put_prev_entity(cfs_rq, se);
  1192. }
  1193. }
  1194. #ifdef CONFIG_SMP
  1195. /**************************************************
  1196. * Fair scheduling class load-balancing methods:
  1197. */
  1198. /*
  1199. * Load-balancing iterator. Note: while the runqueue stays locked
  1200. * during the whole iteration, the current task might be
  1201. * dequeued so the iterator has to be dequeue-safe. Here we
  1202. * achieve that by always pre-iterating before returning
  1203. * the current task:
  1204. */
  1205. static struct task_struct *
  1206. __load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
  1207. {
  1208. struct task_struct *p = NULL;
  1209. struct sched_entity *se;
  1210. while (next != &cfs_rq->tasks) {
  1211. se = list_entry(next, struct sched_entity, group_node);
  1212. next = next->next;
  1213. /* Skip over entities that are not tasks */
  1214. if (entity_is_task(se)) {
  1215. p = task_of(se);
  1216. break;
  1217. }
  1218. }
  1219. cfs_rq->balance_iterator = next;
  1220. return p;
  1221. }
  1222. static struct task_struct *load_balance_start_fair(void *arg)
  1223. {
  1224. struct cfs_rq *cfs_rq = arg;
  1225. return __load_balance_iterator(cfs_rq, cfs_rq->tasks.next);
  1226. }
  1227. static struct task_struct *load_balance_next_fair(void *arg)
  1228. {
  1229. struct cfs_rq *cfs_rq = arg;
  1230. return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
  1231. }
  1232. static unsigned long
  1233. __load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
  1234. unsigned long max_load_move, struct sched_domain *sd,
  1235. enum cpu_idle_type idle, int *all_pinned, int *this_best_prio,
  1236. struct cfs_rq *cfs_rq)
  1237. {
  1238. struct rq_iterator cfs_rq_iterator;
  1239. cfs_rq_iterator.start = load_balance_start_fair;
  1240. cfs_rq_iterator.next = load_balance_next_fair;
  1241. cfs_rq_iterator.arg = cfs_rq;
  1242. return balance_tasks(this_rq, this_cpu, busiest,
  1243. max_load_move, sd, idle, all_pinned,
  1244. this_best_prio, &cfs_rq_iterator);
  1245. }
  1246. #ifdef CONFIG_FAIR_GROUP_SCHED
  1247. static unsigned long
  1248. load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
  1249. unsigned long max_load_move,
  1250. struct sched_domain *sd, enum cpu_idle_type idle,
  1251. int *all_pinned, int *this_best_prio)
  1252. {
  1253. long rem_load_move = max_load_move;
  1254. int busiest_cpu = cpu_of(busiest);
  1255. struct task_group *tg;
  1256. rcu_read_lock();
  1257. update_h_load(busiest_cpu);
  1258. list_for_each_entry(tg, &task_groups, list) {
  1259. struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
  1260. unsigned long busiest_h_load = busiest_cfs_rq->h_load;
  1261. unsigned long busiest_weight = busiest_cfs_rq->load.weight;
  1262. u64 rem_load, moved_load;
  1263. /*
  1264. * empty group
  1265. */
  1266. if (!busiest_cfs_rq->task_weight)
  1267. continue;
  1268. rem_load = (u64)rem_load_move * busiest_weight;
  1269. rem_load = div_u64(rem_load, busiest_h_load + 1);
  1270. moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
  1271. rem_load, sd, idle, all_pinned, this_best_prio,
  1272. tg->cfs_rq[busiest_cpu]);
  1273. if (!moved_load)
  1274. continue;
  1275. moved_load *= busiest_h_load;
  1276. moved_load = div_u64(moved_load, busiest_weight + 1);
  1277. rem_load_move -= moved_load;
  1278. if (rem_load_move < 0)
  1279. break;
  1280. }
  1281. rcu_read_unlock();
  1282. return max_load_move - rem_load_move;
  1283. }
  1284. #else
  1285. static unsigned long
  1286. load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
  1287. unsigned long max_load_move,
  1288. struct sched_domain *sd, enum cpu_idle_type idle,
  1289. int *all_pinned, int *this_best_prio)
  1290. {
  1291. return __load_balance_fair(this_rq, this_cpu, busiest,
  1292. max_load_move, sd, idle, all_pinned,
  1293. this_best_prio, &busiest->cfs);
  1294. }
  1295. #endif
  1296. static int
  1297. move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
  1298. struct sched_domain *sd, enum cpu_idle_type idle)
  1299. {
  1300. struct cfs_rq *busy_cfs_rq;
  1301. struct rq_iterator cfs_rq_iterator;
  1302. cfs_rq_iterator.start = load_balance_start_fair;
  1303. cfs_rq_iterator.next = load_balance_next_fair;
  1304. for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
  1305. /*
  1306. * pass busy_cfs_rq argument into
  1307. * load_balance_[start|next]_fair iterators
  1308. */
  1309. cfs_rq_iterator.arg = busy_cfs_rq;
  1310. if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
  1311. &cfs_rq_iterator))
  1312. return 1;
  1313. }
  1314. return 0;
  1315. }
  1316. #endif /* CONFIG_SMP */
  1317. /*
  1318. * scheduler tick hitting a task of our scheduling class:
  1319. */
  1320. static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
  1321. {
  1322. struct cfs_rq *cfs_rq;
  1323. struct sched_entity *se = &curr->se;
  1324. for_each_sched_entity(se) {
  1325. cfs_rq = cfs_rq_of(se);
  1326. entity_tick(cfs_rq, se, queued);
  1327. }
  1328. }
  1329. #define swap(a, b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0)
  1330. /*
  1331. * Share the fairness runtime between parent and child, thus the
  1332. * total amount of pressure for CPU stays equal - new tasks
  1333. * get a chance to run but frequent forkers are not allowed to
  1334. * monopolize the CPU. Note: the parent runqueue is locked,
  1335. * the child is not running yet.
  1336. */
  1337. static void task_new_fair(struct rq *rq, struct task_struct *p)
  1338. {
  1339. struct cfs_rq *cfs_rq = task_cfs_rq(p);
  1340. struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
  1341. int this_cpu = smp_processor_id();
  1342. sched_info_queued(p);
  1343. update_curr(cfs_rq);
  1344. place_entity(cfs_rq, se, 1);
  1345. /* 'curr' will be NULL if the child belongs to a different group */
  1346. if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) &&
  1347. curr && curr->vruntime < se->vruntime) {
  1348. /*
  1349. * Upon rescheduling, sched_class::put_prev_task() will place
  1350. * 'current' within the tree based on its new key value.
  1351. */
  1352. swap(curr->vruntime, se->vruntime);
  1353. }
  1354. enqueue_task_fair(rq, p, 0);
  1355. resched_task(rq->curr);
  1356. }
  1357. /*
  1358. * Priority of the task has changed. Check to see if we preempt
  1359. * the current task.
  1360. */
  1361. static void prio_changed_fair(struct rq *rq, struct task_struct *p,
  1362. int oldprio, int running)
  1363. {
  1364. /*
  1365. * Reschedule if we are currently running on this runqueue and
  1366. * our priority decreased, or if we are not currently running on
  1367. * this runqueue and our priority is higher than the current's
  1368. */
  1369. if (running) {
  1370. if (p->prio > oldprio)
  1371. resched_task(rq->curr);
  1372. } else
  1373. check_preempt_curr(rq, p);
  1374. }
  1375. /*
  1376. * We switched to the sched_fair class.
  1377. */
  1378. static void switched_to_fair(struct rq *rq, struct task_struct *p,
  1379. int running)
  1380. {
  1381. /*
  1382. * We were most likely switched from sched_rt, so
  1383. * kick off the schedule if running, otherwise just see
  1384. * if we can still preempt the current task.
  1385. */
  1386. if (running)
  1387. resched_task(rq->curr);
  1388. else
  1389. check_preempt_curr(rq, p);
  1390. }
  1391. /* Account for a task changing its policy or group.
  1392. *
  1393. * This routine is mostly called to set cfs_rq->curr field when a task
  1394. * migrates between groups/classes.
  1395. */
  1396. static void set_curr_task_fair(struct rq *rq)
  1397. {
  1398. struct sched_entity *se = &rq->curr->se;
  1399. for_each_sched_entity(se)
  1400. set_next_entity(cfs_rq_of(se), se);
  1401. }
  1402. #ifdef CONFIG_FAIR_GROUP_SCHED
  1403. static void moved_group_fair(struct task_struct *p)
  1404. {
  1405. struct cfs_rq *cfs_rq = task_cfs_rq(p);
  1406. update_curr(cfs_rq);
  1407. place_entity(cfs_rq, &p->se, 1);
  1408. }
  1409. #endif
  1410. /*
  1411. * All the scheduling class methods:
  1412. */
  1413. static const struct sched_class fair_sched_class = {
  1414. .next = &idle_sched_class,
  1415. .enqueue_task = enqueue_task_fair,
  1416. .dequeue_task = dequeue_task_fair,
  1417. .yield_task = yield_task_fair,
  1418. #ifdef CONFIG_SMP
  1419. .select_task_rq = select_task_rq_fair,
  1420. #endif /* CONFIG_SMP */
  1421. .check_preempt_curr = check_preempt_wakeup,
  1422. .pick_next_task = pick_next_task_fair,
  1423. .put_prev_task = put_prev_task_fair,
  1424. #ifdef CONFIG_SMP
  1425. .load_balance = load_balance_fair,
  1426. .move_one_task = move_one_task_fair,
  1427. #endif
  1428. .set_curr_task = set_curr_task_fair,
  1429. .task_tick = task_tick_fair,
  1430. .task_new = task_new_fair,
  1431. .prio_changed = prio_changed_fair,
  1432. .switched_to = switched_to_fair,
  1433. #ifdef CONFIG_FAIR_GROUP_SCHED
  1434. .moved_group = moved_group_fair,
  1435. #endif
  1436. };
  1437. #ifdef CONFIG_SCHED_DEBUG
  1438. static void print_cfs_stats(struct seq_file *m, int cpu)
  1439. {
  1440. struct cfs_rq *cfs_rq;
  1441. rcu_read_lock();
  1442. for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
  1443. print_cfs_rq(m, cpu, cfs_rq);
  1444. rcu_read_unlock();
  1445. }
  1446. #endif