sched_fair.c 41 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. rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
  280. }
  281. static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
  282. {
  283. struct rb_node *left = cfs_rq->rb_leftmost;
  284. if (!left)
  285. return NULL;
  286. return rb_entry(left, struct sched_entity, run_node);
  287. }
  288. static struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
  289. {
  290. struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
  291. if (!last)
  292. return NULL;
  293. return rb_entry(last, struct sched_entity, run_node);
  294. }
  295. /**************************************************************
  296. * Scheduling class statistics methods:
  297. */
  298. #ifdef CONFIG_SCHED_DEBUG
  299. int sched_nr_latency_handler(struct ctl_table *table, int write,
  300. struct file *filp, void __user *buffer, size_t *lenp,
  301. loff_t *ppos)
  302. {
  303. int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
  304. if (ret || !write)
  305. return ret;
  306. sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
  307. sysctl_sched_min_granularity);
  308. return 0;
  309. }
  310. #endif
  311. /*
  312. * delta *= P[w / rw]
  313. */
  314. static inline unsigned long
  315. calc_delta_weight(unsigned long delta, struct sched_entity *se)
  316. {
  317. for_each_sched_entity(se) {
  318. delta = calc_delta_mine(delta,
  319. se->load.weight, &cfs_rq_of(se)->load);
  320. }
  321. return delta;
  322. }
  323. /*
  324. * delta /= w
  325. */
  326. static inline unsigned long
  327. calc_delta_fair(unsigned long delta, struct sched_entity *se)
  328. {
  329. if (unlikely(se->load.weight != NICE_0_LOAD))
  330. delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
  331. return delta;
  332. }
  333. /*
  334. * The idea is to set a period in which each task runs once.
  335. *
  336. * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
  337. * this period because otherwise the slices get too small.
  338. *
  339. * p = (nr <= nl) ? l : l*nr/nl
  340. */
  341. static u64 __sched_period(unsigned long nr_running)
  342. {
  343. u64 period = sysctl_sched_latency;
  344. unsigned long nr_latency = sched_nr_latency;
  345. if (unlikely(nr_running > nr_latency)) {
  346. period = sysctl_sched_min_granularity;
  347. period *= nr_running;
  348. }
  349. return period;
  350. }
  351. /*
  352. * We calculate the wall-time slice from the period by taking a part
  353. * proportional to the weight.
  354. *
  355. * s = p*P[w/rw]
  356. */
  357. static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
  358. {
  359. unsigned long nr_running = cfs_rq->nr_running;
  360. if (unlikely(!se->on_rq))
  361. nr_running++;
  362. return calc_delta_weight(__sched_period(nr_running), se);
  363. }
  364. /*
  365. * We calculate the vruntime slice of a to be inserted task
  366. *
  367. * vs = s/w
  368. */
  369. static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
  370. {
  371. return calc_delta_fair(sched_slice(cfs_rq, se), se);
  372. }
  373. /*
  374. * Update the current task's runtime statistics. Skip current tasks that
  375. * are not in our scheduling class.
  376. */
  377. static inline void
  378. __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
  379. unsigned long delta_exec)
  380. {
  381. unsigned long delta_exec_weighted;
  382. schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
  383. curr->sum_exec_runtime += delta_exec;
  384. schedstat_add(cfs_rq, exec_clock, delta_exec);
  385. delta_exec_weighted = calc_delta_fair(delta_exec, curr);
  386. curr->vruntime += delta_exec_weighted;
  387. update_min_vruntime(cfs_rq);
  388. }
  389. static void update_curr(struct cfs_rq *cfs_rq)
  390. {
  391. struct sched_entity *curr = cfs_rq->curr;
  392. u64 now = rq_of(cfs_rq)->clock;
  393. unsigned long delta_exec;
  394. if (unlikely(!curr))
  395. return;
  396. /*
  397. * Get the amount of time the current task was running
  398. * since the last time we changed load (this cannot
  399. * overflow on 32 bits):
  400. */
  401. delta_exec = (unsigned long)(now - curr->exec_start);
  402. __update_curr(cfs_rq, curr, delta_exec);
  403. curr->exec_start = now;
  404. if (entity_is_task(curr)) {
  405. struct task_struct *curtask = task_of(curr);
  406. cpuacct_charge(curtask, delta_exec);
  407. account_group_exec_runtime(curtask, delta_exec);
  408. }
  409. }
  410. static inline void
  411. update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
  412. {
  413. schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
  414. }
  415. /*
  416. * Task is being enqueued - update stats:
  417. */
  418. static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
  419. {
  420. /*
  421. * Are we enqueueing a waiting task? (for current tasks
  422. * a dequeue/enqueue event is a NOP)
  423. */
  424. if (se != cfs_rq->curr)
  425. update_stats_wait_start(cfs_rq, se);
  426. }
  427. static void
  428. update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
  429. {
  430. schedstat_set(se->wait_max, max(se->wait_max,
  431. rq_of(cfs_rq)->clock - se->wait_start));
  432. schedstat_set(se->wait_count, se->wait_count + 1);
  433. schedstat_set(se->wait_sum, se->wait_sum +
  434. rq_of(cfs_rq)->clock - se->wait_start);
  435. schedstat_set(se->wait_start, 0);
  436. }
  437. static inline void
  438. update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
  439. {
  440. /*
  441. * Mark the end of the wait period if dequeueing a
  442. * waiting task:
  443. */
  444. if (se != cfs_rq->curr)
  445. update_stats_wait_end(cfs_rq, se);
  446. }
  447. /*
  448. * We are picking a new current task - update its stats:
  449. */
  450. static inline void
  451. update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
  452. {
  453. /*
  454. * We are starting a new run period:
  455. */
  456. se->exec_start = rq_of(cfs_rq)->clock;
  457. }
  458. /**************************************************
  459. * Scheduling class queueing methods:
  460. */
  461. #if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
  462. static void
  463. add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
  464. {
  465. cfs_rq->task_weight += weight;
  466. }
  467. #else
  468. static inline void
  469. add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
  470. {
  471. }
  472. #endif
  473. static void
  474. account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
  475. {
  476. update_load_add(&cfs_rq->load, se->load.weight);
  477. if (!parent_entity(se))
  478. inc_cpu_load(rq_of(cfs_rq), se->load.weight);
  479. if (entity_is_task(se)) {
  480. add_cfs_task_weight(cfs_rq, se->load.weight);
  481. list_add(&se->group_node, &cfs_rq->tasks);
  482. }
  483. cfs_rq->nr_running++;
  484. se->on_rq = 1;
  485. }
  486. static void
  487. account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
  488. {
  489. update_load_sub(&cfs_rq->load, se->load.weight);
  490. if (!parent_entity(se))
  491. dec_cpu_load(rq_of(cfs_rq), se->load.weight);
  492. if (entity_is_task(se)) {
  493. add_cfs_task_weight(cfs_rq, -se->load.weight);
  494. list_del_init(&se->group_node);
  495. }
  496. cfs_rq->nr_running--;
  497. se->on_rq = 0;
  498. }
  499. static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
  500. {
  501. #ifdef CONFIG_SCHEDSTATS
  502. if (se->sleep_start) {
  503. u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
  504. struct task_struct *tsk = task_of(se);
  505. if ((s64)delta < 0)
  506. delta = 0;
  507. if (unlikely(delta > se->sleep_max))
  508. se->sleep_max = delta;
  509. se->sleep_start = 0;
  510. se->sum_sleep_runtime += delta;
  511. account_scheduler_latency(tsk, delta >> 10, 1);
  512. }
  513. if (se->block_start) {
  514. u64 delta = rq_of(cfs_rq)->clock - se->block_start;
  515. struct task_struct *tsk = task_of(se);
  516. if ((s64)delta < 0)
  517. delta = 0;
  518. if (unlikely(delta > se->block_max))
  519. se->block_max = delta;
  520. se->block_start = 0;
  521. se->sum_sleep_runtime += delta;
  522. /*
  523. * Blocking time is in units of nanosecs, so shift by 20 to
  524. * get a milliseconds-range estimation of the amount of
  525. * time that the task spent sleeping:
  526. */
  527. if (unlikely(prof_on == SLEEP_PROFILING)) {
  528. profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
  529. delta >> 20);
  530. }
  531. account_scheduler_latency(tsk, delta >> 10, 0);
  532. }
  533. #endif
  534. }
  535. static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
  536. {
  537. #ifdef CONFIG_SCHED_DEBUG
  538. s64 d = se->vruntime - cfs_rq->min_vruntime;
  539. if (d < 0)
  540. d = -d;
  541. if (d > 3*sysctl_sched_latency)
  542. schedstat_inc(cfs_rq, nr_spread_over);
  543. #endif
  544. }
  545. static void
  546. place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
  547. {
  548. u64 vruntime = cfs_rq->min_vruntime;
  549. /*
  550. * The 'current' period is already promised to the current tasks,
  551. * however the extra weight of the new task will slow them down a
  552. * little, place the new task so that it fits in the slot that
  553. * stays open at the end.
  554. */
  555. if (initial && sched_feat(START_DEBIT))
  556. vruntime += sched_vslice(cfs_rq, se);
  557. if (!initial) {
  558. /* sleeps upto a single latency don't count. */
  559. if (sched_feat(NEW_FAIR_SLEEPERS)) {
  560. unsigned long thresh = sysctl_sched_latency;
  561. /*
  562. * convert the sleeper threshold into virtual time
  563. */
  564. if (sched_feat(NORMALIZED_SLEEPER))
  565. thresh = calc_delta_fair(thresh, se);
  566. vruntime -= thresh;
  567. }
  568. /* ensure we never gain time by being placed backwards. */
  569. vruntime = max_vruntime(se->vruntime, vruntime);
  570. }
  571. se->vruntime = vruntime;
  572. }
  573. static void
  574. enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
  575. {
  576. /*
  577. * Update run-time statistics of the 'current'.
  578. */
  579. update_curr(cfs_rq);
  580. account_entity_enqueue(cfs_rq, se);
  581. if (wakeup) {
  582. place_entity(cfs_rq, se, 0);
  583. enqueue_sleeper(cfs_rq, se);
  584. }
  585. update_stats_enqueue(cfs_rq, se);
  586. check_spread(cfs_rq, se);
  587. if (se != cfs_rq->curr)
  588. __enqueue_entity(cfs_rq, se);
  589. }
  590. static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
  591. {
  592. if (cfs_rq->last == se)
  593. cfs_rq->last = NULL;
  594. if (cfs_rq->next == se)
  595. cfs_rq->next = NULL;
  596. }
  597. static void
  598. dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
  599. {
  600. /*
  601. * Update run-time statistics of the 'current'.
  602. */
  603. update_curr(cfs_rq);
  604. update_stats_dequeue(cfs_rq, se);
  605. if (sleep) {
  606. #ifdef CONFIG_SCHEDSTATS
  607. if (entity_is_task(se)) {
  608. struct task_struct *tsk = task_of(se);
  609. if (tsk->state & TASK_INTERRUPTIBLE)
  610. se->sleep_start = rq_of(cfs_rq)->clock;
  611. if (tsk->state & TASK_UNINTERRUPTIBLE)
  612. se->block_start = rq_of(cfs_rq)->clock;
  613. }
  614. #endif
  615. }
  616. clear_buddies(cfs_rq, se);
  617. if (se != cfs_rq->curr)
  618. __dequeue_entity(cfs_rq, se);
  619. account_entity_dequeue(cfs_rq, se);
  620. update_min_vruntime(cfs_rq);
  621. }
  622. /*
  623. * Preempt the current task with a newly woken task if needed:
  624. */
  625. static void
  626. check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
  627. {
  628. unsigned long ideal_runtime, delta_exec;
  629. ideal_runtime = sched_slice(cfs_rq, curr);
  630. delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
  631. if (delta_exec > ideal_runtime)
  632. resched_task(rq_of(cfs_rq)->curr);
  633. }
  634. static void
  635. set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
  636. {
  637. /* 'current' is not kept within the tree. */
  638. if (se->on_rq) {
  639. /*
  640. * Any task has to be enqueued before it get to execute on
  641. * a CPU. So account for the time it spent waiting on the
  642. * runqueue.
  643. */
  644. update_stats_wait_end(cfs_rq, se);
  645. __dequeue_entity(cfs_rq, se);
  646. }
  647. update_stats_curr_start(cfs_rq, se);
  648. cfs_rq->curr = se;
  649. #ifdef CONFIG_SCHEDSTATS
  650. /*
  651. * Track our maximum slice length, if the CPU's load is at
  652. * least twice that of our own weight (i.e. dont track it
  653. * when there are only lesser-weight tasks around):
  654. */
  655. if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
  656. se->slice_max = max(se->slice_max,
  657. se->sum_exec_runtime - se->prev_sum_exec_runtime);
  658. }
  659. #endif
  660. se->prev_sum_exec_runtime = se->sum_exec_runtime;
  661. }
  662. static int
  663. wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
  664. static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
  665. {
  666. struct sched_entity *se = __pick_next_entity(cfs_rq);
  667. if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, se) < 1)
  668. return cfs_rq->next;
  669. if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, se) < 1)
  670. return cfs_rq->last;
  671. return se;
  672. }
  673. static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
  674. {
  675. /*
  676. * If still on the runqueue then deactivate_task()
  677. * was not called and update_curr() has to be done:
  678. */
  679. if (prev->on_rq)
  680. update_curr(cfs_rq);
  681. check_spread(cfs_rq, prev);
  682. if (prev->on_rq) {
  683. update_stats_wait_start(cfs_rq, prev);
  684. /* Put 'current' back into the tree. */
  685. __enqueue_entity(cfs_rq, prev);
  686. }
  687. cfs_rq->curr = NULL;
  688. }
  689. static void
  690. entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
  691. {
  692. /*
  693. * Update run-time statistics of the 'current'.
  694. */
  695. update_curr(cfs_rq);
  696. #ifdef CONFIG_SCHED_HRTICK
  697. /*
  698. * queued ticks are scheduled to match the slice, so don't bother
  699. * validating it and just reschedule.
  700. */
  701. if (queued) {
  702. resched_task(rq_of(cfs_rq)->curr);
  703. return;
  704. }
  705. /*
  706. * don't let the period tick interfere with the hrtick preemption
  707. */
  708. if (!sched_feat(DOUBLE_TICK) &&
  709. hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
  710. return;
  711. #endif
  712. if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
  713. check_preempt_tick(cfs_rq, curr);
  714. }
  715. /**************************************************
  716. * CFS operations on tasks:
  717. */
  718. #ifdef CONFIG_SCHED_HRTICK
  719. static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
  720. {
  721. struct sched_entity *se = &p->se;
  722. struct cfs_rq *cfs_rq = cfs_rq_of(se);
  723. WARN_ON(task_rq(p) != rq);
  724. if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) {
  725. u64 slice = sched_slice(cfs_rq, se);
  726. u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
  727. s64 delta = slice - ran;
  728. if (delta < 0) {
  729. if (rq->curr == p)
  730. resched_task(p);
  731. return;
  732. }
  733. /*
  734. * Don't schedule slices shorter than 10000ns, that just
  735. * doesn't make sense. Rely on vruntime for fairness.
  736. */
  737. if (rq->curr != p)
  738. delta = max_t(s64, 10000LL, delta);
  739. hrtick_start(rq, delta);
  740. }
  741. }
  742. /*
  743. * called from enqueue/dequeue and updates the hrtick when the
  744. * current task is from our class and nr_running is low enough
  745. * to matter.
  746. */
  747. static void hrtick_update(struct rq *rq)
  748. {
  749. struct task_struct *curr = rq->curr;
  750. if (curr->sched_class != &fair_sched_class)
  751. return;
  752. if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
  753. hrtick_start_fair(rq, curr);
  754. }
  755. #else /* !CONFIG_SCHED_HRTICK */
  756. static inline void
  757. hrtick_start_fair(struct rq *rq, struct task_struct *p)
  758. {
  759. }
  760. static inline void hrtick_update(struct rq *rq)
  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_update(rq);
  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_update(rq);
  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. clear_buddies(cfs_rq, se);
  817. if (likely(!sysctl_sched_compat_yield) && curr->policy != SCHED_BATCH) {
  818. update_rq_clock(rq);
  819. /*
  820. * Update run-time statistics of the 'current'.
  821. */
  822. update_curr(cfs_rq);
  823. return;
  824. }
  825. /*
  826. * Find the rightmost entry in the rbtree:
  827. */
  828. rightmost = __pick_last_entity(cfs_rq);
  829. /*
  830. * Already in the rightmost position?
  831. */
  832. if (unlikely(!rightmost || rightmost->vruntime < se->vruntime))
  833. return;
  834. /*
  835. * Minimally necessary key value to be last in the tree:
  836. * Upon rescheduling, sched_class::put_prev_task() will place
  837. * 'current' within the tree based on its new key value.
  838. */
  839. se->vruntime = rightmost->vruntime + 1;
  840. }
  841. /*
  842. * wake_idle() will wake a task on an idle cpu if task->cpu is
  843. * not idle and an idle cpu is available. The span of cpus to
  844. * search starts with cpus closest then further out as needed,
  845. * so we always favor a closer, idle cpu.
  846. * Domains may include CPUs that are not usable for migration,
  847. * hence we need to mask them out (cpu_active_map)
  848. *
  849. * Returns the CPU we should wake onto.
  850. */
  851. #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
  852. static int wake_idle(int cpu, struct task_struct *p)
  853. {
  854. cpumask_t tmp;
  855. struct sched_domain *sd;
  856. int i;
  857. /*
  858. * If it is idle, then it is the best cpu to run this task.
  859. *
  860. * This cpu is also the best, if it has more than one task already.
  861. * Siblings must be also busy(in most cases) as they didn't already
  862. * pickup the extra load from this cpu and hence we need not check
  863. * sibling runqueue info. This will avoid the checks and cache miss
  864. * penalities associated with that.
  865. */
  866. if (idle_cpu(cpu) || cpu_rq(cpu)->cfs.nr_running > 1)
  867. return cpu;
  868. for_each_domain(cpu, sd) {
  869. if ((sd->flags & SD_WAKE_IDLE)
  870. || ((sd->flags & SD_WAKE_IDLE_FAR)
  871. && !task_hot(p, task_rq(p)->clock, sd))) {
  872. cpus_and(tmp, sd->span, p->cpus_allowed);
  873. cpus_and(tmp, tmp, cpu_active_map);
  874. for_each_cpu_mask_nr(i, tmp) {
  875. if (idle_cpu(i)) {
  876. if (i != task_cpu(p)) {
  877. schedstat_inc(p,
  878. se.nr_wakeups_idle);
  879. }
  880. return i;
  881. }
  882. }
  883. } else {
  884. break;
  885. }
  886. }
  887. return cpu;
  888. }
  889. #else /* !ARCH_HAS_SCHED_WAKE_IDLE*/
  890. static inline int wake_idle(int cpu, struct task_struct *p)
  891. {
  892. return cpu;
  893. }
  894. #endif
  895. #ifdef CONFIG_SMP
  896. #ifdef CONFIG_FAIR_GROUP_SCHED
  897. /*
  898. * effective_load() calculates the load change as seen from the root_task_group
  899. *
  900. * Adding load to a group doesn't make a group heavier, but can cause movement
  901. * of group shares between cpus. Assuming the shares were perfectly aligned one
  902. * can calculate the shift in shares.
  903. *
  904. * The problem is that perfectly aligning the shares is rather expensive, hence
  905. * we try to avoid doing that too often - see update_shares(), which ratelimits
  906. * this change.
  907. *
  908. * We compensate this by not only taking the current delta into account, but
  909. * also considering the delta between when the shares were last adjusted and
  910. * now.
  911. *
  912. * We still saw a performance dip, some tracing learned us that between
  913. * cgroup:/ and cgroup:/foo balancing the number of affine wakeups increased
  914. * significantly. Therefore try to bias the error in direction of failing
  915. * the affine wakeup.
  916. *
  917. */
  918. static long effective_load(struct task_group *tg, int cpu,
  919. long wl, long wg)
  920. {
  921. struct sched_entity *se = tg->se[cpu];
  922. if (!tg->parent)
  923. return wl;
  924. /*
  925. * By not taking the decrease of shares on the other cpu into
  926. * account our error leans towards reducing the affine wakeups.
  927. */
  928. if (!wl && sched_feat(ASYM_EFF_LOAD))
  929. return wl;
  930. for_each_sched_entity(se) {
  931. long S, rw, s, a, b;
  932. long more_w;
  933. /*
  934. * Instead of using this increment, also add the difference
  935. * between when the shares were last updated and now.
  936. */
  937. more_w = se->my_q->load.weight - se->my_q->rq_weight;
  938. wl += more_w;
  939. wg += more_w;
  940. S = se->my_q->tg->shares;
  941. s = se->my_q->shares;
  942. rw = se->my_q->rq_weight;
  943. a = S*(rw + wl);
  944. b = S*rw + s*wg;
  945. wl = s*(a-b);
  946. if (likely(b))
  947. wl /= b;
  948. /*
  949. * Assume the group is already running and will
  950. * thus already be accounted for in the weight.
  951. *
  952. * That is, moving shares between CPUs, does not
  953. * alter the group weight.
  954. */
  955. wg = 0;
  956. }
  957. return wl;
  958. }
  959. #else
  960. static inline unsigned long effective_load(struct task_group *tg, int cpu,
  961. unsigned long wl, unsigned long wg)
  962. {
  963. return wl;
  964. }
  965. #endif
  966. static int
  967. wake_affine(struct sched_domain *this_sd, struct rq *this_rq,
  968. struct task_struct *p, int prev_cpu, int this_cpu, int sync,
  969. int idx, unsigned long load, unsigned long this_load,
  970. unsigned int imbalance)
  971. {
  972. struct task_struct *curr = this_rq->curr;
  973. struct task_group *tg;
  974. unsigned long tl = this_load;
  975. unsigned long tl_per_task;
  976. unsigned long weight;
  977. int balanced;
  978. if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
  979. return 0;
  980. if (sync && (curr->se.avg_overlap > sysctl_sched_migration_cost ||
  981. p->se.avg_overlap > sysctl_sched_migration_cost))
  982. sync = 0;
  983. /*
  984. * If sync wakeup then subtract the (maximum possible)
  985. * effect of the currently running task from the load
  986. * of the current CPU:
  987. */
  988. if (sync) {
  989. tg = task_group(current);
  990. weight = current->se.load.weight;
  991. tl += effective_load(tg, this_cpu, -weight, -weight);
  992. load += effective_load(tg, prev_cpu, 0, -weight);
  993. }
  994. tg = task_group(p);
  995. weight = p->se.load.weight;
  996. balanced = 100*(tl + effective_load(tg, this_cpu, weight, weight)) <=
  997. imbalance*(load + effective_load(tg, prev_cpu, 0, weight));
  998. /*
  999. * If the currently running task will sleep within
  1000. * a reasonable amount of time then attract this newly
  1001. * woken task:
  1002. */
  1003. if (sync && balanced)
  1004. return 1;
  1005. schedstat_inc(p, se.nr_wakeups_affine_attempts);
  1006. tl_per_task = cpu_avg_load_per_task(this_cpu);
  1007. if (balanced || (tl <= load && tl + target_load(prev_cpu, idx) <=
  1008. tl_per_task)) {
  1009. /*
  1010. * This domain has SD_WAKE_AFFINE and
  1011. * p is cache cold in this domain, and
  1012. * there is no bad imbalance.
  1013. */
  1014. schedstat_inc(this_sd, ttwu_move_affine);
  1015. schedstat_inc(p, se.nr_wakeups_affine);
  1016. return 1;
  1017. }
  1018. return 0;
  1019. }
  1020. static int select_task_rq_fair(struct task_struct *p, int sync)
  1021. {
  1022. struct sched_domain *sd, *this_sd = NULL;
  1023. int prev_cpu, this_cpu, new_cpu;
  1024. unsigned long load, this_load;
  1025. struct rq *this_rq;
  1026. unsigned int imbalance;
  1027. int idx;
  1028. prev_cpu = task_cpu(p);
  1029. this_cpu = smp_processor_id();
  1030. this_rq = cpu_rq(this_cpu);
  1031. new_cpu = prev_cpu;
  1032. if (prev_cpu == this_cpu)
  1033. goto out;
  1034. /*
  1035. * 'this_sd' is the first domain that both
  1036. * this_cpu and prev_cpu are present in:
  1037. */
  1038. for_each_domain(this_cpu, sd) {
  1039. if (cpu_isset(prev_cpu, sd->span)) {
  1040. this_sd = sd;
  1041. break;
  1042. }
  1043. }
  1044. if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
  1045. goto out;
  1046. /*
  1047. * Check for affine wakeup and passive balancing possibilities.
  1048. */
  1049. if (!this_sd)
  1050. goto out;
  1051. idx = this_sd->wake_idx;
  1052. imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
  1053. load = source_load(prev_cpu, idx);
  1054. this_load = target_load(this_cpu, idx);
  1055. if (wake_affine(this_sd, this_rq, p, prev_cpu, this_cpu, sync, idx,
  1056. load, this_load, imbalance))
  1057. return this_cpu;
  1058. /*
  1059. * Start passive balancing when half the imbalance_pct
  1060. * limit is reached.
  1061. */
  1062. if (this_sd->flags & SD_WAKE_BALANCE) {
  1063. if (imbalance*this_load <= 100*load) {
  1064. schedstat_inc(this_sd, ttwu_move_balance);
  1065. schedstat_inc(p, se.nr_wakeups_passive);
  1066. return this_cpu;
  1067. }
  1068. }
  1069. out:
  1070. return wake_idle(new_cpu, p);
  1071. }
  1072. #endif /* CONFIG_SMP */
  1073. static unsigned long wakeup_gran(struct sched_entity *se)
  1074. {
  1075. unsigned long gran = sysctl_sched_wakeup_granularity;
  1076. /*
  1077. * More easily preempt - nice tasks, while not making it harder for
  1078. * + nice tasks.
  1079. */
  1080. if (!sched_feat(ASYM_GRAN) || se->load.weight > NICE_0_LOAD)
  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. static void set_last_buddy(struct sched_entity *se)
  1110. {
  1111. for_each_sched_entity(se)
  1112. cfs_rq_of(se)->last = se;
  1113. }
  1114. static void set_next_buddy(struct sched_entity *se)
  1115. {
  1116. for_each_sched_entity(se)
  1117. cfs_rq_of(se)->next = se;
  1118. }
  1119. /*
  1120. * Preempt the current task with a newly woken task if needed:
  1121. */
  1122. static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
  1123. {
  1124. struct task_struct *curr = rq->curr;
  1125. struct sched_entity *se = &curr->se, *pse = &p->se;
  1126. if (unlikely(rt_prio(p->prio))) {
  1127. struct cfs_rq *cfs_rq = task_cfs_rq(curr);
  1128. update_rq_clock(rq);
  1129. update_curr(cfs_rq);
  1130. resched_task(curr);
  1131. return;
  1132. }
  1133. if (unlikely(p->sched_class != &fair_sched_class))
  1134. return;
  1135. if (unlikely(se == pse))
  1136. return;
  1137. /*
  1138. * Only set the backward buddy when the current task is still on the
  1139. * rq. This can happen when a wakeup gets interleaved with schedule on
  1140. * the ->pre_schedule() or idle_balance() point, either of which can
  1141. * drop the rq lock.
  1142. *
  1143. * Also, during early boot the idle thread is in the fair class, for
  1144. * obvious reasons its a bad idea to schedule back to the idle thread.
  1145. */
  1146. if (sched_feat(LAST_BUDDY) && likely(se->on_rq && curr != rq->idle))
  1147. set_last_buddy(se);
  1148. set_next_buddy(pse);
  1149. /*
  1150. * We can come here with TIF_NEED_RESCHED already set from new task
  1151. * wake up path.
  1152. */
  1153. if (test_tsk_need_resched(curr))
  1154. return;
  1155. /*
  1156. * Batch tasks do not preempt (their preemption is driven by
  1157. * the tick):
  1158. */
  1159. if (unlikely(p->policy == SCHED_BATCH))
  1160. return;
  1161. if (!sched_feat(WAKEUP_PREEMPT))
  1162. return;
  1163. if (sched_feat(WAKEUP_OVERLAP) && (sync ||
  1164. (se->avg_overlap < sysctl_sched_migration_cost &&
  1165. pse->avg_overlap < sysctl_sched_migration_cost))) {
  1166. resched_task(curr);
  1167. return;
  1168. }
  1169. find_matching_se(&se, &pse);
  1170. while (se) {
  1171. BUG_ON(!pse);
  1172. if (wakeup_preempt_entity(se, pse) == 1) {
  1173. resched_task(curr);
  1174. break;
  1175. }
  1176. se = parent_entity(se);
  1177. pse = parent_entity(pse);
  1178. }
  1179. }
  1180. static struct task_struct *pick_next_task_fair(struct rq *rq)
  1181. {
  1182. struct task_struct *p;
  1183. struct cfs_rq *cfs_rq = &rq->cfs;
  1184. struct sched_entity *se;
  1185. if (unlikely(!cfs_rq->nr_running))
  1186. return NULL;
  1187. do {
  1188. se = pick_next_entity(cfs_rq);
  1189. set_next_entity(cfs_rq, se);
  1190. cfs_rq = group_cfs_rq(se);
  1191. } while (cfs_rq);
  1192. p = task_of(se);
  1193. hrtick_start_fair(rq, p);
  1194. return p;
  1195. }
  1196. /*
  1197. * Account for a descheduled task:
  1198. */
  1199. static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
  1200. {
  1201. struct sched_entity *se = &prev->se;
  1202. struct cfs_rq *cfs_rq;
  1203. for_each_sched_entity(se) {
  1204. cfs_rq = cfs_rq_of(se);
  1205. put_prev_entity(cfs_rq, se);
  1206. }
  1207. }
  1208. #ifdef CONFIG_SMP
  1209. /**************************************************
  1210. * Fair scheduling class load-balancing methods:
  1211. */
  1212. /*
  1213. * Load-balancing iterator. Note: while the runqueue stays locked
  1214. * during the whole iteration, the current task might be
  1215. * dequeued so the iterator has to be dequeue-safe. Here we
  1216. * achieve that by always pre-iterating before returning
  1217. * the current task:
  1218. */
  1219. static struct task_struct *
  1220. __load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
  1221. {
  1222. struct task_struct *p = NULL;
  1223. struct sched_entity *se;
  1224. if (next == &cfs_rq->tasks)
  1225. return NULL;
  1226. se = list_entry(next, struct sched_entity, group_node);
  1227. p = task_of(se);
  1228. cfs_rq->balance_iterator = next->next;
  1229. return p;
  1230. }
  1231. static struct task_struct *load_balance_start_fair(void *arg)
  1232. {
  1233. struct cfs_rq *cfs_rq = arg;
  1234. return __load_balance_iterator(cfs_rq, cfs_rq->tasks.next);
  1235. }
  1236. static struct task_struct *load_balance_next_fair(void *arg)
  1237. {
  1238. struct cfs_rq *cfs_rq = arg;
  1239. return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
  1240. }
  1241. static unsigned long
  1242. __load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
  1243. unsigned long max_load_move, struct sched_domain *sd,
  1244. enum cpu_idle_type idle, int *all_pinned, int *this_best_prio,
  1245. struct cfs_rq *cfs_rq)
  1246. {
  1247. struct rq_iterator cfs_rq_iterator;
  1248. cfs_rq_iterator.start = load_balance_start_fair;
  1249. cfs_rq_iterator.next = load_balance_next_fair;
  1250. cfs_rq_iterator.arg = cfs_rq;
  1251. return balance_tasks(this_rq, this_cpu, busiest,
  1252. max_load_move, sd, idle, all_pinned,
  1253. this_best_prio, &cfs_rq_iterator);
  1254. }
  1255. #ifdef CONFIG_FAIR_GROUP_SCHED
  1256. static unsigned long
  1257. load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
  1258. unsigned long max_load_move,
  1259. struct sched_domain *sd, enum cpu_idle_type idle,
  1260. int *all_pinned, int *this_best_prio)
  1261. {
  1262. long rem_load_move = max_load_move;
  1263. int busiest_cpu = cpu_of(busiest);
  1264. struct task_group *tg;
  1265. rcu_read_lock();
  1266. update_h_load(busiest_cpu);
  1267. list_for_each_entry_rcu(tg, &task_groups, list) {
  1268. struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
  1269. unsigned long busiest_h_load = busiest_cfs_rq->h_load;
  1270. unsigned long busiest_weight = busiest_cfs_rq->load.weight;
  1271. u64 rem_load, moved_load;
  1272. /*
  1273. * empty group
  1274. */
  1275. if (!busiest_cfs_rq->task_weight)
  1276. continue;
  1277. rem_load = (u64)rem_load_move * busiest_weight;
  1278. rem_load = div_u64(rem_load, busiest_h_load + 1);
  1279. moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
  1280. rem_load, sd, idle, all_pinned, this_best_prio,
  1281. tg->cfs_rq[busiest_cpu]);
  1282. if (!moved_load)
  1283. continue;
  1284. moved_load *= busiest_h_load;
  1285. moved_load = div_u64(moved_load, busiest_weight + 1);
  1286. rem_load_move -= moved_load;
  1287. if (rem_load_move < 0)
  1288. break;
  1289. }
  1290. rcu_read_unlock();
  1291. return max_load_move - rem_load_move;
  1292. }
  1293. #else
  1294. static unsigned long
  1295. load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
  1296. unsigned long max_load_move,
  1297. struct sched_domain *sd, enum cpu_idle_type idle,
  1298. int *all_pinned, int *this_best_prio)
  1299. {
  1300. return __load_balance_fair(this_rq, this_cpu, busiest,
  1301. max_load_move, sd, idle, all_pinned,
  1302. this_best_prio, &busiest->cfs);
  1303. }
  1304. #endif
  1305. static int
  1306. move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
  1307. struct sched_domain *sd, enum cpu_idle_type idle)
  1308. {
  1309. struct cfs_rq *busy_cfs_rq;
  1310. struct rq_iterator cfs_rq_iterator;
  1311. cfs_rq_iterator.start = load_balance_start_fair;
  1312. cfs_rq_iterator.next = load_balance_next_fair;
  1313. for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
  1314. /*
  1315. * pass busy_cfs_rq argument into
  1316. * load_balance_[start|next]_fair iterators
  1317. */
  1318. cfs_rq_iterator.arg = busy_cfs_rq;
  1319. if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
  1320. &cfs_rq_iterator))
  1321. return 1;
  1322. }
  1323. return 0;
  1324. }
  1325. #endif /* CONFIG_SMP */
  1326. /*
  1327. * scheduler tick hitting a task of our scheduling class:
  1328. */
  1329. static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
  1330. {
  1331. struct cfs_rq *cfs_rq;
  1332. struct sched_entity *se = &curr->se;
  1333. for_each_sched_entity(se) {
  1334. cfs_rq = cfs_rq_of(se);
  1335. entity_tick(cfs_rq, se, queued);
  1336. }
  1337. }
  1338. #define swap(a, b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0)
  1339. /*
  1340. * Share the fairness runtime between parent and child, thus the
  1341. * total amount of pressure for CPU stays equal - new tasks
  1342. * get a chance to run but frequent forkers are not allowed to
  1343. * monopolize the CPU. Note: the parent runqueue is locked,
  1344. * the child is not running yet.
  1345. */
  1346. static void task_new_fair(struct rq *rq, struct task_struct *p)
  1347. {
  1348. struct cfs_rq *cfs_rq = task_cfs_rq(p);
  1349. struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
  1350. int this_cpu = smp_processor_id();
  1351. sched_info_queued(p);
  1352. update_curr(cfs_rq);
  1353. place_entity(cfs_rq, se, 1);
  1354. /* 'curr' will be NULL if the child belongs to a different group */
  1355. if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) &&
  1356. curr && curr->vruntime < se->vruntime) {
  1357. /*
  1358. * Upon rescheduling, sched_class::put_prev_task() will place
  1359. * 'current' within the tree based on its new key value.
  1360. */
  1361. swap(curr->vruntime, se->vruntime);
  1362. resched_task(rq->curr);
  1363. }
  1364. enqueue_task_fair(rq, p, 0);
  1365. }
  1366. /*
  1367. * Priority of the task has changed. Check to see if we preempt
  1368. * the current task.
  1369. */
  1370. static void prio_changed_fair(struct rq *rq, struct task_struct *p,
  1371. int oldprio, int running)
  1372. {
  1373. /*
  1374. * Reschedule if we are currently running on this runqueue and
  1375. * our priority decreased, or if we are not currently running on
  1376. * this runqueue and our priority is higher than the current's
  1377. */
  1378. if (running) {
  1379. if (p->prio > oldprio)
  1380. resched_task(rq->curr);
  1381. } else
  1382. check_preempt_curr(rq, p, 0);
  1383. }
  1384. /*
  1385. * We switched to the sched_fair class.
  1386. */
  1387. static void switched_to_fair(struct rq *rq, struct task_struct *p,
  1388. int running)
  1389. {
  1390. /*
  1391. * We were most likely switched from sched_rt, so
  1392. * kick off the schedule if running, otherwise just see
  1393. * if we can still preempt the current task.
  1394. */
  1395. if (running)
  1396. resched_task(rq->curr);
  1397. else
  1398. check_preempt_curr(rq, p, 0);
  1399. }
  1400. /* Account for a task changing its policy or group.
  1401. *
  1402. * This routine is mostly called to set cfs_rq->curr field when a task
  1403. * migrates between groups/classes.
  1404. */
  1405. static void set_curr_task_fair(struct rq *rq)
  1406. {
  1407. struct sched_entity *se = &rq->curr->se;
  1408. for_each_sched_entity(se)
  1409. set_next_entity(cfs_rq_of(se), se);
  1410. }
  1411. #ifdef CONFIG_FAIR_GROUP_SCHED
  1412. static void moved_group_fair(struct task_struct *p)
  1413. {
  1414. struct cfs_rq *cfs_rq = task_cfs_rq(p);
  1415. update_curr(cfs_rq);
  1416. place_entity(cfs_rq, &p->se, 1);
  1417. }
  1418. #endif
  1419. /*
  1420. * All the scheduling class methods:
  1421. */
  1422. static const struct sched_class fair_sched_class = {
  1423. .next = &idle_sched_class,
  1424. .enqueue_task = enqueue_task_fair,
  1425. .dequeue_task = dequeue_task_fair,
  1426. .yield_task = yield_task_fair,
  1427. .check_preempt_curr = check_preempt_wakeup,
  1428. .pick_next_task = pick_next_task_fair,
  1429. .put_prev_task = put_prev_task_fair,
  1430. #ifdef CONFIG_SMP
  1431. .select_task_rq = select_task_rq_fair,
  1432. .load_balance = load_balance_fair,
  1433. .move_one_task = move_one_task_fair,
  1434. #endif
  1435. .set_curr_task = set_curr_task_fair,
  1436. .task_tick = task_tick_fair,
  1437. .task_new = task_new_fair,
  1438. .prio_changed = prio_changed_fair,
  1439. .switched_to = switched_to_fair,
  1440. #ifdef CONFIG_FAIR_GROUP_SCHED
  1441. .moved_group = moved_group_fair,
  1442. #endif
  1443. };
  1444. #ifdef CONFIG_SCHED_DEBUG
  1445. static void print_cfs_stats(struct seq_file *m, int cpu)
  1446. {
  1447. struct cfs_rq *cfs_rq;
  1448. rcu_read_lock();
  1449. for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
  1450. print_cfs_rq(m, cpu, cfs_rq);
  1451. rcu_read_unlock();
  1452. }
  1453. #endif