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