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1 /*
2 * kernel/sched.c
3 *
4 * Kernel scheduler and related syscalls
5 *
6 * Copyright (C) 1991-2002 Linus Torvalds
7 *
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
11 * by Andrea Arcangeli
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
22 * by Peter Williams
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
27 */
28
29 #include <linux/mm.h>
30 #include <linux/module.h>
31 #include <linux/nmi.h>
32 #include <linux/init.h>
33 #include <linux/uaccess.h>
34 #include <linux/highmem.h>
35 #include <linux/smp_lock.h>
36 #include <asm/mmu_context.h>
37 #include <linux/interrupt.h>
38 #include <linux/capability.h>
39 #include <linux/completion.h>
40 #include <linux/kernel_stat.h>
41 #include <linux/debug_locks.h>
42 #include <linux/perf_counter.h>
43 #include <linux/security.h>
44 #include <linux/notifier.h>
45 #include <linux/profile.h>
46 #include <linux/freezer.h>
47 #include <linux/vmalloc.h>
48 #include <linux/blkdev.h>
49 #include <linux/delay.h>
50 #include <linux/pid_namespace.h>
51 #include <linux/smp.h>
52 #include <linux/threads.h>
53 #include <linux/timer.h>
54 #include <linux/rcupdate.h>
55 #include <linux/cpu.h>
56 #include <linux/cpuset.h>
57 #include <linux/percpu.h>
58 #include <linux/kthread.h>
59 #include <linux/proc_fs.h>
60 #include <linux/seq_file.h>
61 #include <linux/sysctl.h>
62 #include <linux/syscalls.h>
63 #include <linux/times.h>
64 #include <linux/tsacct_kern.h>
65 #include <linux/kprobes.h>
66 #include <linux/delayacct.h>
67 #include <linux/reciprocal_div.h>
68 #include <linux/unistd.h>
69 #include <linux/pagemap.h>
70 #include <linux/hrtimer.h>
71 #include <linux/tick.h>
72 #include <linux/debugfs.h>
73 #include <linux/ctype.h>
74 #include <linux/ftrace.h>
75
76 #include <asm/tlb.h>
77 #include <asm/irq_regs.h>
78
79 #include "sched_cpupri.h"
80
81 #define CREATE_TRACE_POINTS
82 #include <trace/events/sched.h>
83
84 /*
85 * Convert user-nice values [ -20 ... 0 ... 19 ]
86 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
87 * and back.
88 */
89 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
90 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
91 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
92
93 /*
94 * 'User priority' is the nice value converted to something we
95 * can work with better when scaling various scheduler parameters,
96 * it's a [ 0 ... 39 ] range.
97 */
98 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
99 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
100 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
101
102 /*
103 * Helpers for converting nanosecond timing to jiffy resolution
104 */
105 #define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
106
107 #define NICE_0_LOAD SCHED_LOAD_SCALE
108 #define NICE_0_SHIFT SCHED_LOAD_SHIFT
109
110 /*
111 * These are the 'tuning knobs' of the scheduler:
112 *
113 * default timeslice is 100 msecs (used only for SCHED_RR tasks).
114 * Timeslices get refilled after they expire.
115 */
116 #define DEF_TIMESLICE (100 * HZ / 1000)
117
118 /*
119 * single value that denotes runtime == period, ie unlimited time.
120 */
121 #define RUNTIME_INF ((u64)~0ULL)
122
123 #ifdef CONFIG_SMP
124
125 static void double_rq_lock(struct rq *rq1, struct rq *rq2);
126
127 /*
128 * Divide a load by a sched group cpu_power : (load / sg->__cpu_power)
129 * Since cpu_power is a 'constant', we can use a reciprocal divide.
130 */
131 static inline u32 sg_div_cpu_power(const struct sched_group *sg, u32 load)
132 {
133 return reciprocal_divide(load, sg->reciprocal_cpu_power);
134 }
135
136 /*
137 * Each time a sched group cpu_power is changed,
138 * we must compute its reciprocal value
139 */
140 static inline void sg_inc_cpu_power(struct sched_group *sg, u32 val)
141 {
142 sg->__cpu_power += val;
143 sg->reciprocal_cpu_power = reciprocal_value(sg->__cpu_power);
144 }
145 #endif
146
147 static inline int rt_policy(int policy)
148 {
149 if (unlikely(policy == SCHED_FIFO || policy == SCHED_RR))
150 return 1;
151 return 0;
152 }
153
154 static inline int task_has_rt_policy(struct task_struct *p)
155 {
156 return rt_policy(p->policy);
157 }
158
159 /*
160 * This is the priority-queue data structure of the RT scheduling class:
161 */
162 struct rt_prio_array {
163 DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
164 struct list_head queue[MAX_RT_PRIO];
165 };
166
167 struct rt_bandwidth {
168 /* nests inside the rq lock: */
169 spinlock_t rt_runtime_lock;
170 ktime_t rt_period;
171 u64 rt_runtime;
172 struct hrtimer rt_period_timer;
173 };
174
175 static struct rt_bandwidth def_rt_bandwidth;
176
177 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
178
179 static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
180 {
181 struct rt_bandwidth *rt_b =
182 container_of(timer, struct rt_bandwidth, rt_period_timer);
183 ktime_t now;
184 int overrun;
185 int idle = 0;
186
187 for (;;) {
188 now = hrtimer_cb_get_time(timer);
189 overrun = hrtimer_forward(timer, now, rt_b->rt_period);
190
191 if (!overrun)
192 break;
193
194 idle = do_sched_rt_period_timer(rt_b, overrun);
195 }
196
197 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
198 }
199
200 static
201 void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
202 {
203 rt_b->rt_period = ns_to_ktime(period);
204 rt_b->rt_runtime = runtime;
205
206 spin_lock_init(&rt_b->rt_runtime_lock);
207
208 hrtimer_init(&rt_b->rt_period_timer,
209 CLOCK_MONOTONIC, HRTIMER_MODE_REL);
210 rt_b->rt_period_timer.function = sched_rt_period_timer;
211 }
212
213 static inline int rt_bandwidth_enabled(void)
214 {
215 return sysctl_sched_rt_runtime >= 0;
216 }
217
218 static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
219 {
220 ktime_t now;
221
222 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
223 return;
224
225 if (hrtimer_active(&rt_b->rt_period_timer))
226 return;
227
228 spin_lock(&rt_b->rt_runtime_lock);
229 for (;;) {
230 unsigned long delta;
231 ktime_t soft, hard;
232
233 if (hrtimer_active(&rt_b->rt_period_timer))
234 break;
235
236 now = hrtimer_cb_get_time(&rt_b->rt_period_timer);
237 hrtimer_forward(&rt_b->rt_period_timer, now, rt_b->rt_period);
238
239 soft = hrtimer_get_softexpires(&rt_b->rt_period_timer);
240 hard = hrtimer_get_expires(&rt_b->rt_period_timer);
241 delta = ktime_to_ns(ktime_sub(hard, soft));
242 __hrtimer_start_range_ns(&rt_b->rt_period_timer, soft, delta,
243 HRTIMER_MODE_ABS_PINNED, 0);
244 }
245 spin_unlock(&rt_b->rt_runtime_lock);
246 }
247
248 #ifdef CONFIG_RT_GROUP_SCHED
249 static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
250 {
251 hrtimer_cancel(&rt_b->rt_period_timer);
252 }
253 #endif
254
255 /*
256 * sched_domains_mutex serializes calls to arch_init_sched_domains,
257 * detach_destroy_domains and partition_sched_domains.
258 */
259 static DEFINE_MUTEX(sched_domains_mutex);
260
261 #ifdef CONFIG_GROUP_SCHED
262
263 #include <linux/cgroup.h>
264
265 struct cfs_rq;
266
267 static LIST_HEAD(task_groups);
268
269 /* task group related information */
270 struct task_group {
271 #ifdef CONFIG_CGROUP_SCHED
272 struct cgroup_subsys_state css;
273 #endif
274
275 #ifdef CONFIG_USER_SCHED
276 uid_t uid;
277 #endif
278
279 #ifdef CONFIG_FAIR_GROUP_SCHED
280 /* schedulable entities of this group on each cpu */
281 struct sched_entity **se;
282 /* runqueue "owned" by this group on each cpu */
283 struct cfs_rq **cfs_rq;
284 unsigned long shares;
285 #endif
286
287 #ifdef CONFIG_RT_GROUP_SCHED
288 struct sched_rt_entity **rt_se;
289 struct rt_rq **rt_rq;
290
291 struct rt_bandwidth rt_bandwidth;
292 #endif
293
294 struct rcu_head rcu;
295 struct list_head list;
296
297 struct task_group *parent;
298 struct list_head siblings;
299 struct list_head children;
300 };
301
302 #ifdef CONFIG_USER_SCHED
303
304 /* Helper function to pass uid information to create_sched_user() */
305 void set_tg_uid(struct user_struct *user)
306 {
307 user->tg->uid = user->uid;
308 }
309
310 /*
311 * Root task group.
312 * Every UID task group (including init_task_group aka UID-0) will
313 * be a child to this group.
314 */
315 struct task_group root_task_group;
316
317 #ifdef CONFIG_FAIR_GROUP_SCHED
318 /* Default task group's sched entity on each cpu */
319 static DEFINE_PER_CPU(struct sched_entity, init_sched_entity);
320 /* Default task group's cfs_rq on each cpu */
321 static DEFINE_PER_CPU(struct cfs_rq, init_cfs_rq) ____cacheline_aligned_in_smp;
322 #endif /* CONFIG_FAIR_GROUP_SCHED */
323
324 #ifdef CONFIG_RT_GROUP_SCHED
325 static DEFINE_PER_CPU(struct sched_rt_entity, init_sched_rt_entity);
326 static DEFINE_PER_CPU(struct rt_rq, init_rt_rq) ____cacheline_aligned_in_smp;
327 #endif /* CONFIG_RT_GROUP_SCHED */
328 #else /* !CONFIG_USER_SCHED */
329 #define root_task_group init_task_group
330 #endif /* CONFIG_USER_SCHED */
331
332 /* task_group_lock serializes add/remove of task groups and also changes to
333 * a task group's cpu shares.
334 */
335 static DEFINE_SPINLOCK(task_group_lock);
336
337 #ifdef CONFIG_SMP
338 static int root_task_group_empty(void)
339 {
340 return list_empty(&root_task_group.children);
341 }
342 #endif
343
344 #ifdef CONFIG_FAIR_GROUP_SCHED
345 #ifdef CONFIG_USER_SCHED
346 # define INIT_TASK_GROUP_LOAD (2*NICE_0_LOAD)
347 #else /* !CONFIG_USER_SCHED */
348 # define INIT_TASK_GROUP_LOAD NICE_0_LOAD
349 #endif /* CONFIG_USER_SCHED */
350
351 /*
352 * A weight of 0 or 1 can cause arithmetics problems.
353 * A weight of a cfs_rq is the sum of weights of which entities
354 * are queued on this cfs_rq, so a weight of a entity should not be
355 * too large, so as the shares value of a task group.
356 * (The default weight is 1024 - so there's no practical
357 * limitation from this.)
358 */
359 #define MIN_SHARES 2
360 #define MAX_SHARES (1UL << 18)
361
362 static int init_task_group_load = INIT_TASK_GROUP_LOAD;
363 #endif
364
365 /* Default task group.
366 * Every task in system belong to this group at bootup.
367 */
368 struct task_group init_task_group;
369
370 /* return group to which a task belongs */
371 static inline struct task_group *task_group(struct task_struct *p)
372 {
373 struct task_group *tg;
374
375 #ifdef CONFIG_USER_SCHED
376 rcu_read_lock();
377 tg = __task_cred(p)->user->tg;
378 rcu_read_unlock();
379 #elif defined(CONFIG_CGROUP_SCHED)
380 tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
381 struct task_group, css);
382 #else
383 tg = &init_task_group;
384 #endif
385 return tg;
386 }
387
388 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
389 static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
390 {
391 #ifdef CONFIG_FAIR_GROUP_SCHED
392 p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
393 p->se.parent = task_group(p)->se[cpu];
394 #endif
395
396 #ifdef CONFIG_RT_GROUP_SCHED
397 p->rt.rt_rq = task_group(p)->rt_rq[cpu];
398 p->rt.parent = task_group(p)->rt_se[cpu];
399 #endif
400 }
401
402 #else
403
404 #ifdef CONFIG_SMP
405 static int root_task_group_empty(void)
406 {
407 return 1;
408 }
409 #endif
410
411 static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
412 static inline struct task_group *task_group(struct task_struct *p)
413 {
414 return NULL;
415 }
416
417 #endif /* CONFIG_GROUP_SCHED */
418
419 /* CFS-related fields in a runqueue */
420 struct cfs_rq {
421 struct load_weight load;
422 unsigned long nr_running;
423
424 u64 exec_clock;
425 u64 min_vruntime;
426
427 struct rb_root tasks_timeline;
428 struct rb_node *rb_leftmost;
429
430 struct list_head tasks;
431 struct list_head *balance_iterator;
432
433 /*
434 * 'curr' points to currently running entity on this cfs_rq.
435 * It is set to NULL otherwise (i.e when none are currently running).
436 */
437 struct sched_entity *curr, *next, *last;
438
439 unsigned int nr_spread_over;
440
441 #ifdef CONFIG_FAIR_GROUP_SCHED
442 struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
443
444 /*
445 * leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
446 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
447 * (like users, containers etc.)
448 *
449 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
450 * list is used during load balance.
451 */
452 struct list_head leaf_cfs_rq_list;
453 struct task_group *tg; /* group that "owns" this runqueue */
454
455 #ifdef CONFIG_SMP
456 /*
457 * the part of load.weight contributed by tasks
458 */
459 unsigned long task_weight;
460
461 /*
462 * h_load = weight * f(tg)
463 *
464 * Where f(tg) is the recursive weight fraction assigned to
465 * this group.
466 */
467 unsigned long h_load;
468
469 /*
470 * this cpu's part of tg->shares
471 */
472 unsigned long shares;
473
474 /*
475 * load.weight at the time we set shares
476 */
477 unsigned long rq_weight;
478 #endif
479 #endif
480 };
481
482 /* Real-Time classes' related field in a runqueue: */
483 struct rt_rq {
484 struct rt_prio_array active;
485 unsigned long rt_nr_running;
486 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
487 struct {
488 int curr; /* highest queued rt task prio */
489 #ifdef CONFIG_SMP
490 int next; /* next highest */
491 #endif
492 } highest_prio;
493 #endif
494 #ifdef CONFIG_SMP
495 unsigned long rt_nr_migratory;
496 unsigned long rt_nr_total;
497 int overloaded;
498 struct plist_head pushable_tasks;
499 #endif
500 int rt_throttled;
501 u64 rt_time;
502 u64 rt_runtime;
503 /* Nests inside the rq lock: */
504 spinlock_t rt_runtime_lock;
505
506 #ifdef CONFIG_RT_GROUP_SCHED
507 unsigned long rt_nr_boosted;
508
509 struct rq *rq;
510 struct list_head leaf_rt_rq_list;
511 struct task_group *tg;
512 struct sched_rt_entity *rt_se;
513 #endif
514 };
515
516 #ifdef CONFIG_SMP
517
518 /*
519 * We add the notion of a root-domain which will be used to define per-domain
520 * variables. Each exclusive cpuset essentially defines an island domain by
521 * fully partitioning the member cpus from any other cpuset. Whenever a new
522 * exclusive cpuset is created, we also create and attach a new root-domain
523 * object.
524 *
525 */
526 struct root_domain {
527 atomic_t refcount;
528 cpumask_var_t span;
529 cpumask_var_t online;
530
531 /*
532 * The "RT overload" flag: it gets set if a CPU has more than
533 * one runnable RT task.
534 */
535 cpumask_var_t rto_mask;
536 atomic_t rto_count;
537 #ifdef CONFIG_SMP
538 struct cpupri cpupri;
539 #endif
540 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
541 /*
542 * Preferred wake up cpu nominated by sched_mc balance that will be
543 * used when most cpus are idle in the system indicating overall very
544 * low system utilisation. Triggered at POWERSAVINGS_BALANCE_WAKEUP(2)
545 */
546 unsigned int sched_mc_preferred_wakeup_cpu;
547 #endif
548 };
549
550 /*
551 * By default the system creates a single root-domain with all cpus as
552 * members (mimicking the global state we have today).
553 */
554 static struct root_domain def_root_domain;
555
556 #endif
557
558 /*
559 * This is the main, per-CPU runqueue data structure.
560 *
561 * Locking rule: those places that want to lock multiple runqueues
562 * (such as the load balancing or the thread migration code), lock
563 * acquire operations must be ordered by ascending &runqueue.
564 */
565 struct rq {
566 /* runqueue lock: */
567 spinlock_t lock;
568
569 /*
570 * nr_running and cpu_load should be in the same cacheline because
571 * remote CPUs use both these fields when doing load calculation.
572 */
573 unsigned long nr_running;
574 #define CPU_LOAD_IDX_MAX 5
575 unsigned long cpu_load[CPU_LOAD_IDX_MAX];
576 #ifdef CONFIG_NO_HZ
577 unsigned long last_tick_seen;
578 unsigned char in_nohz_recently;
579 #endif
580 /* capture load from *all* tasks on this cpu: */
581 struct load_weight load;
582 unsigned long nr_load_updates;
583 u64 nr_switches;
584 u64 nr_migrations_in;
585
586 struct cfs_rq cfs;
587 struct rt_rq rt;
588
589 #ifdef CONFIG_FAIR_GROUP_SCHED
590 /* list of leaf cfs_rq on this cpu: */
591 struct list_head leaf_cfs_rq_list;
592 #endif
593 #ifdef CONFIG_RT_GROUP_SCHED
594 struct list_head leaf_rt_rq_list;
595 #endif
596
597 /*
598 * This is part of a global counter where only the total sum
599 * over all CPUs matters. A task can increase this counter on
600 * one CPU and if it got migrated afterwards it may decrease
601 * it on another CPU. Always updated under the runqueue lock:
602 */
603 unsigned long nr_uninterruptible;
604
605 struct task_struct *curr, *idle;
606 unsigned long next_balance;
607 struct mm_struct *prev_mm;
608
609 u64 clock;
610
611 atomic_t nr_iowait;
612
613 #ifdef CONFIG_SMP
614 struct root_domain *rd;
615 struct sched_domain *sd;
616
617 unsigned char idle_at_tick;
618 /* For active balancing */
619 int active_balance;
620 int push_cpu;
621 /* cpu of this runqueue: */
622 int cpu;
623 int online;
624
625 unsigned long avg_load_per_task;
626
627 struct task_struct *migration_thread;
628 struct list_head migration_queue;
629 #endif
630
631 /* calc_load related fields */
632 unsigned long calc_load_update;
633 long calc_load_active;
634
635 #ifdef CONFIG_SCHED_HRTICK
636 #ifdef CONFIG_SMP
637 int hrtick_csd_pending;
638 struct call_single_data hrtick_csd;
639 #endif
640 struct hrtimer hrtick_timer;
641 #endif
642
643 #ifdef CONFIG_SCHEDSTATS
644 /* latency stats */
645 struct sched_info rq_sched_info;
646 unsigned long long rq_cpu_time;
647 /* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
648
649 /* sys_sched_yield() stats */
650 unsigned int yld_count;
651
652 /* schedule() stats */
653 unsigned int sched_switch;
654 unsigned int sched_count;
655 unsigned int sched_goidle;
656
657 /* try_to_wake_up() stats */
658 unsigned int ttwu_count;
659 unsigned int ttwu_local;
660
661 /* BKL stats */
662 unsigned int bkl_count;
663 #endif
664 };
665
666 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
667
668 static inline void check_preempt_curr(struct rq *rq, struct task_struct *p, int sync)
669 {
670 rq->curr->sched_class->check_preempt_curr(rq, p, sync);
671 }
672
673 static inline int cpu_of(struct rq *rq)
674 {
675 #ifdef CONFIG_SMP
676 return rq->cpu;
677 #else
678 return 0;
679 #endif
680 }
681
682 /*
683 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
684 * See detach_destroy_domains: synchronize_sched for details.
685 *
686 * The domain tree of any CPU may only be accessed from within
687 * preempt-disabled sections.
688 */
689 #define for_each_domain(cpu, __sd) \
690 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
691
692 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
693 #define this_rq() (&__get_cpu_var(runqueues))
694 #define task_rq(p) cpu_rq(task_cpu(p))
695 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
696
697 inline void update_rq_clock(struct rq *rq)
698 {
699 rq->clock = sched_clock_cpu(cpu_of(rq));
700 }
701
702 /*
703 * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
704 */
705 #ifdef CONFIG_SCHED_DEBUG
706 # define const_debug __read_mostly
707 #else
708 # define const_debug static const
709 #endif
710
711 /**
712 * runqueue_is_locked
713 *
714 * Returns true if the current cpu runqueue is locked.
715 * This interface allows printk to be called with the runqueue lock
716 * held and know whether or not it is OK to wake up the klogd.
717 */
718 int runqueue_is_locked(void)
719 {
720 int cpu = get_cpu();
721 struct rq *rq = cpu_rq(cpu);
722 int ret;
723
724 ret = spin_is_locked(&rq->lock);
725 put_cpu();
726 return ret;
727 }
728
729 /*
730 * Debugging: various feature bits
731 */
732
733 #define SCHED_FEAT(name, enabled) \
734 __SCHED_FEAT_##name ,
735
736 enum {
737 #include "sched_features.h"
738 };
739
740 #undef SCHED_FEAT
741
742 #define SCHED_FEAT(name, enabled) \
743 (1UL << __SCHED_FEAT_##name) * enabled |
744
745 const_debug unsigned int sysctl_sched_features =
746 #include "sched_features.h"
747 0;
748
749 #undef SCHED_FEAT
750
751 #ifdef CONFIG_SCHED_DEBUG
752 #define SCHED_FEAT(name, enabled) \
753 #name ,
754
755 static __read_mostly char *sched_feat_names[] = {
756 #include "sched_features.h"
757 NULL
758 };
759
760 #undef SCHED_FEAT
761
762 static int sched_feat_show(struct seq_file *m, void *v)
763 {
764 int i;
765
766 for (i = 0; sched_feat_names[i]; i++) {
767 if (!(sysctl_sched_features & (1UL << i)))
768 seq_puts(m, "NO_");
769 seq_printf(m, "%s ", sched_feat_names[i]);
770 }
771 seq_puts(m, "\n");
772
773 return 0;
774 }
775
776 static ssize_t
777 sched_feat_write(struct file *filp, const char __user *ubuf,
778 size_t cnt, loff_t *ppos)
779 {
780 char buf[64];
781 char *cmp = buf;
782 int neg = 0;
783 int i;
784
785 if (cnt > 63)
786 cnt = 63;
787
788 if (copy_from_user(&buf, ubuf, cnt))
789 return -EFAULT;
790
791 buf[cnt] = 0;
792
793 if (strncmp(buf, "NO_", 3) == 0) {
794 neg = 1;
795 cmp += 3;
796 }
797
798 for (i = 0; sched_feat_names[i]; i++) {
799 int len = strlen(sched_feat_names[i]);
800
801 if (strncmp(cmp, sched_feat_names[i], len) == 0) {
802 if (neg)
803 sysctl_sched_features &= ~(1UL << i);
804 else
805 sysctl_sched_features |= (1UL << i);
806 break;
807 }
808 }
809
810 if (!sched_feat_names[i])
811 return -EINVAL;
812
813 filp->f_pos += cnt;
814
815 return cnt;
816 }
817
818 static int sched_feat_open(struct inode *inode, struct file *filp)
819 {
820 return single_open(filp, sched_feat_show, NULL);
821 }
822
823 static struct file_operations sched_feat_fops = {
824 .open = sched_feat_open,
825 .write = sched_feat_write,
826 .read = seq_read,
827 .llseek = seq_lseek,
828 .release = single_release,
829 };
830
831 static __init int sched_init_debug(void)
832 {
833 debugfs_create_file("sched_features", 0644, NULL, NULL,
834 &sched_feat_fops);
835
836 return 0;
837 }
838 late_initcall(sched_init_debug);
839
840 #endif
841
842 #define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
843
844 /*
845 * Number of tasks to iterate in a single balance run.
846 * Limited because this is done with IRQs disabled.
847 */
848 const_debug unsigned int sysctl_sched_nr_migrate = 32;
849
850 /*
851 * ratelimit for updating the group shares.
852 * default: 0.25ms
853 */
854 unsigned int sysctl_sched_shares_ratelimit = 250000;
855
856 /*
857 * Inject some fuzzyness into changing the per-cpu group shares
858 * this avoids remote rq-locks at the expense of fairness.
859 * default: 4
860 */
861 unsigned int sysctl_sched_shares_thresh = 4;
862
863 /*
864 * period over which we measure -rt task cpu usage in us.
865 * default: 1s
866 */
867 unsigned int sysctl_sched_rt_period = 1000000;
868
869 static __read_mostly int scheduler_running;
870
871 /*
872 * part of the period that we allow rt tasks to run in us.
873 * default: 0.95s
874 */
875 int sysctl_sched_rt_runtime = 950000;
876
877 static inline u64 global_rt_period(void)
878 {
879 return (u64)sysctl_sched_rt_period * NSEC_PER_USEC;
880 }
881
882 static inline u64 global_rt_runtime(void)
883 {
884 if (sysctl_sched_rt_runtime < 0)
885 return RUNTIME_INF;
886
887 return (u64)sysctl_sched_rt_runtime * NSEC_PER_USEC;
888 }
889
890 #ifndef prepare_arch_switch
891 # define prepare_arch_switch(next) do { } while (0)
892 #endif
893 #ifndef finish_arch_switch
894 # define finish_arch_switch(prev) do { } while (0)
895 #endif
896
897 static inline int task_current(struct rq *rq, struct task_struct *p)
898 {
899 return rq->curr == p;
900 }
901
902 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
903 static inline int task_running(struct rq *rq, struct task_struct *p)
904 {
905 return task_current(rq, p);
906 }
907
908 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
909 {
910 }
911
912 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
913 {
914 #ifdef CONFIG_DEBUG_SPINLOCK
915 /* this is a valid case when another task releases the spinlock */
916 rq->lock.owner = current;
917 #endif
918 /*
919 * If we are tracking spinlock dependencies then we have to
920 * fix up the runqueue lock - which gets 'carried over' from
921 * prev into current:
922 */
923 spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
924
925 spin_unlock_irq(&rq->lock);
926 }
927
928 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
929 static inline int task_running(struct rq *rq, struct task_struct *p)
930 {
931 #ifdef CONFIG_SMP
932 return p->oncpu;
933 #else
934 return task_current(rq, p);
935 #endif
936 }
937
938 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
939 {
940 #ifdef CONFIG_SMP
941 /*
942 * We can optimise this out completely for !SMP, because the
943 * SMP rebalancing from interrupt is the only thing that cares
944 * here.
945 */
946 next->oncpu = 1;
947 #endif
948 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
949 spin_unlock_irq(&rq->lock);
950 #else
951 spin_unlock(&rq->lock);
952 #endif
953 }
954
955 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
956 {
957 #ifdef CONFIG_SMP
958 /*
959 * After ->oncpu is cleared, the task can be moved to a different CPU.
960 * We must ensure this doesn't happen until the switch is completely
961 * finished.
962 */
963 smp_wmb();
964 prev->oncpu = 0;
965 #endif
966 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
967 local_irq_enable();
968 #endif
969 }
970 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
971
972 /*
973 * __task_rq_lock - lock the runqueue a given task resides on.
974 * Must be called interrupts disabled.
975 */
976 static inline struct rq *__task_rq_lock(struct task_struct *p)
977 __acquires(rq->lock)
978 {
979 for (;;) {
980 struct rq *rq = task_rq(p);
981 spin_lock(&rq->lock);
982 if (likely(rq == task_rq(p)))
983 return rq;
984 spin_unlock(&rq->lock);
985 }
986 }
987
988 /*
989 * task_rq_lock - lock the runqueue a given task resides on and disable
990 * interrupts. Note the ordering: we can safely lookup the task_rq without
991 * explicitly disabling preemption.
992 */
993 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
994 __acquires(rq->lock)
995 {
996 struct rq *rq;
997
998 for (;;) {
999 local_irq_save(*flags);
1000 rq = task_rq(p);
1001 spin_lock(&rq->lock);
1002 if (likely(rq == task_rq(p)))
1003 return rq;
1004 spin_unlock_irqrestore(&rq->lock, *flags);
1005 }
1006 }
1007
1008 void task_rq_unlock_wait(struct task_struct *p)
1009 {
1010 struct rq *rq = task_rq(p);
1011
1012 smp_mb(); /* spin-unlock-wait is not a full memory barrier */
1013 spin_unlock_wait(&rq->lock);
1014 }
1015
1016 static void __task_rq_unlock(struct rq *rq)
1017 __releases(rq->lock)
1018 {
1019 spin_unlock(&rq->lock);
1020 }
1021
1022 static inline void task_rq_unlock(struct rq *rq, unsigned long *flags)
1023 __releases(rq->lock)
1024 {
1025 spin_unlock_irqrestore(&rq->lock, *flags);
1026 }
1027
1028 /*
1029 * this_rq_lock - lock this runqueue and disable interrupts.
1030 */
1031 static struct rq *this_rq_lock(void)
1032 __acquires(rq->lock)
1033 {
1034 struct rq *rq;
1035
1036 local_irq_disable();
1037 rq = this_rq();
1038 spin_lock(&rq->lock);
1039
1040 return rq;
1041 }
1042
1043 #ifdef CONFIG_SCHED_HRTICK
1044 /*
1045 * Use HR-timers to deliver accurate preemption points.
1046 *
1047 * Its all a bit involved since we cannot program an hrt while holding the
1048 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
1049 * reschedule event.
1050 *
1051 * When we get rescheduled we reprogram the hrtick_timer outside of the
1052 * rq->lock.
1053 */
1054
1055 /*
1056 * Use hrtick when:
1057 * - enabled by features
1058 * - hrtimer is actually high res
1059 */
1060 static inline int hrtick_enabled(struct rq *rq)
1061 {
1062 if (!sched_feat(HRTICK))
1063 return 0;
1064 if (!cpu_active(cpu_of(rq)))
1065 return 0;
1066 return hrtimer_is_hres_active(&rq->hrtick_timer);
1067 }
1068
1069 static void hrtick_clear(struct rq *rq)
1070 {
1071 if (hrtimer_active(&rq->hrtick_timer))
1072 hrtimer_cancel(&rq->hrtick_timer);
1073 }
1074
1075 /*
1076 * High-resolution timer tick.
1077 * Runs from hardirq context with interrupts disabled.
1078 */
1079 static enum hrtimer_restart hrtick(struct hrtimer *timer)
1080 {
1081 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
1082
1083 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
1084
1085 spin_lock(&rq->lock);
1086 update_rq_clock(rq);
1087 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
1088 spin_unlock(&rq->lock);
1089
1090 return HRTIMER_NORESTART;
1091 }
1092
1093 #ifdef CONFIG_SMP
1094 /*
1095 * called from hardirq (IPI) context
1096 */
1097 static void __hrtick_start(void *arg)
1098 {
1099 struct rq *rq = arg;
1100
1101 spin_lock(&rq->lock);
1102 hrtimer_restart(&rq->hrtick_timer);
1103 rq->hrtick_csd_pending = 0;
1104 spin_unlock(&rq->lock);
1105 }
1106
1107 /*
1108 * Called to set the hrtick timer state.
1109 *
1110 * called with rq->lock held and irqs disabled
1111 */
1112 static void hrtick_start(struct rq *rq, u64 delay)
1113 {
1114 struct hrtimer *timer = &rq->hrtick_timer;
1115 ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
1116
1117 hrtimer_set_expires(timer, time);
1118
1119 if (rq == this_rq()) {
1120 hrtimer_restart(timer);
1121 } else if (!rq->hrtick_csd_pending) {
1122 __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
1123 rq->hrtick_csd_pending = 1;
1124 }
1125 }
1126
1127 static int
1128 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
1129 {
1130 int cpu = (int)(long)hcpu;
1131
1132 switch (action) {
1133 case CPU_UP_CANCELED:
1134 case CPU_UP_CANCELED_FROZEN:
1135 case CPU_DOWN_PREPARE:
1136 case CPU_DOWN_PREPARE_FROZEN:
1137 case CPU_DEAD:
1138 case CPU_DEAD_FROZEN:
1139 hrtick_clear(cpu_rq(cpu));
1140 return NOTIFY_OK;
1141 }
1142
1143 return NOTIFY_DONE;
1144 }
1145
1146 static __init void init_hrtick(void)
1147 {
1148 hotcpu_notifier(hotplug_hrtick, 0);
1149 }
1150 #else
1151 /*
1152 * Called to set the hrtick timer state.
1153 *
1154 * called with rq->lock held and irqs disabled
1155 */
1156 static void hrtick_start(struct rq *rq, u64 delay)
1157 {
1158 __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
1159 HRTIMER_MODE_REL_PINNED, 0);
1160 }
1161
1162 static inline void init_hrtick(void)
1163 {
1164 }
1165 #endif /* CONFIG_SMP */
1166
1167 static void init_rq_hrtick(struct rq *rq)
1168 {
1169 #ifdef CONFIG_SMP
1170 rq->hrtick_csd_pending = 0;
1171
1172 rq->hrtick_csd.flags = 0;
1173 rq->hrtick_csd.func = __hrtick_start;
1174 rq->hrtick_csd.info = rq;
1175 #endif
1176
1177 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1178 rq->hrtick_timer.function = hrtick;
1179 }
1180 #else /* CONFIG_SCHED_HRTICK */
1181 static inline void hrtick_clear(struct rq *rq)
1182 {
1183 }
1184
1185 static inline void init_rq_hrtick(struct rq *rq)
1186 {
1187 }
1188
1189 static inline void init_hrtick(void)
1190 {
1191 }
1192 #endif /* CONFIG_SCHED_HRTICK */
1193
1194 /*
1195 * resched_task - mark a task 'to be rescheduled now'.
1196 *
1197 * On UP this means the setting of the need_resched flag, on SMP it
1198 * might also involve a cross-CPU call to trigger the scheduler on
1199 * the target CPU.
1200 */
1201 #ifdef CONFIG_SMP
1202
1203 #ifndef tsk_is_polling
1204 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1205 #endif
1206
1207 static void resched_task(struct task_struct *p)
1208 {
1209 int cpu;
1210
1211 assert_spin_locked(&task_rq(p)->lock);
1212
1213 if (test_tsk_need_resched(p))
1214 return;
1215
1216 set_tsk_need_resched(p);
1217
1218 cpu = task_cpu(p);
1219 if (cpu == smp_processor_id())
1220 return;
1221
1222 /* NEED_RESCHED must be visible before we test polling */
1223 smp_mb();
1224 if (!tsk_is_polling(p))
1225 smp_send_reschedule(cpu);
1226 }
1227
1228 static void resched_cpu(int cpu)
1229 {
1230 struct rq *rq = cpu_rq(cpu);
1231 unsigned long flags;
1232
1233 if (!spin_trylock_irqsave(&rq->lock, flags))
1234 return;
1235 resched_task(cpu_curr(cpu));
1236 spin_unlock_irqrestore(&rq->lock, flags);
1237 }
1238
1239 #ifdef CONFIG_NO_HZ
1240 /*
1241 * When add_timer_on() enqueues a timer into the timer wheel of an
1242 * idle CPU then this timer might expire before the next timer event
1243 * which is scheduled to wake up that CPU. In case of a completely
1244 * idle system the next event might even be infinite time into the
1245 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
1246 * leaves the inner idle loop so the newly added timer is taken into
1247 * account when the CPU goes back to idle and evaluates the timer
1248 * wheel for the next timer event.
1249 */
1250 void wake_up_idle_cpu(int cpu)
1251 {
1252 struct rq *rq = cpu_rq(cpu);
1253
1254 if (cpu == smp_processor_id())
1255 return;
1256
1257 /*
1258 * This is safe, as this function is called with the timer
1259 * wheel base lock of (cpu) held. When the CPU is on the way
1260 * to idle and has not yet set rq->curr to idle then it will
1261 * be serialized on the timer wheel base lock and take the new
1262 * timer into account automatically.
1263 */
1264 if (rq->curr != rq->idle)
1265 return;
1266
1267 /*
1268 * We can set TIF_RESCHED on the idle task of the other CPU
1269 * lockless. The worst case is that the other CPU runs the
1270 * idle task through an additional NOOP schedule()
1271 */
1272 set_tsk_need_resched(rq->idle);
1273
1274 /* NEED_RESCHED must be visible before we test polling */
1275 smp_mb();
1276 if (!tsk_is_polling(rq->idle))
1277 smp_send_reschedule(cpu);
1278 }
1279 #endif /* CONFIG_NO_HZ */
1280
1281 #else /* !CONFIG_SMP */
1282 static void resched_task(struct task_struct *p)
1283 {
1284 assert_spin_locked(&task_rq(p)->lock);
1285 set_tsk_need_resched(p);
1286 }
1287 #endif /* CONFIG_SMP */
1288
1289 #if BITS_PER_LONG == 32
1290 # define WMULT_CONST (~0UL)
1291 #else
1292 # define WMULT_CONST (1UL << 32)
1293 #endif
1294
1295 #define WMULT_SHIFT 32
1296
1297 /*
1298 * Shift right and round:
1299 */
1300 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
1301
1302 /*
1303 * delta *= weight / lw
1304 */
1305 static unsigned long
1306 calc_delta_mine(unsigned long delta_exec, unsigned long weight,
1307 struct load_weight *lw)
1308 {
1309 u64 tmp;
1310
1311 if (!lw->inv_weight) {
1312 if (BITS_PER_LONG > 32 && unlikely(lw->weight >= WMULT_CONST))
1313 lw->inv_weight = 1;
1314 else
1315 lw->inv_weight = 1 + (WMULT_CONST-lw->weight/2)
1316 / (lw->weight+1);
1317 }
1318
1319 tmp = (u64)delta_exec * weight;
1320 /*
1321 * Check whether we'd overflow the 64-bit multiplication:
1322 */
1323 if (unlikely(tmp > WMULT_CONST))
1324 tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
1325 WMULT_SHIFT/2);
1326 else
1327 tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
1328
1329 return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
1330 }
1331
1332 static inline void update_load_add(struct load_weight *lw, unsigned long inc)
1333 {
1334 lw->weight += inc;
1335 lw->inv_weight = 0;
1336 }
1337
1338 static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
1339 {
1340 lw->weight -= dec;
1341 lw->inv_weight = 0;
1342 }
1343
1344 /*
1345 * To aid in avoiding the subversion of "niceness" due to uneven distribution
1346 * of tasks with abnormal "nice" values across CPUs the contribution that
1347 * each task makes to its run queue's load is weighted according to its
1348 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
1349 * scaled version of the new time slice allocation that they receive on time
1350 * slice expiry etc.
1351 */
1352
1353 #define WEIGHT_IDLEPRIO 3
1354 #define WMULT_IDLEPRIO 1431655765
1355
1356 /*
1357 * Nice levels are multiplicative, with a gentle 10% change for every
1358 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
1359 * nice 1, it will get ~10% less CPU time than another CPU-bound task
1360 * that remained on nice 0.
1361 *
1362 * The "10% effect" is relative and cumulative: from _any_ nice level,
1363 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
1364 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
1365 * If a task goes up by ~10% and another task goes down by ~10% then
1366 * the relative distance between them is ~25%.)
1367 */
1368 static const int prio_to_weight[40] = {
1369 /* -20 */ 88761, 71755, 56483, 46273, 36291,
1370 /* -15 */ 29154, 23254, 18705, 14949, 11916,
1371 /* -10 */ 9548, 7620, 6100, 4904, 3906,
1372 /* -5 */ 3121, 2501, 1991, 1586, 1277,
1373 /* 0 */ 1024, 820, 655, 526, 423,
1374 /* 5 */ 335, 272, 215, 172, 137,
1375 /* 10 */ 110, 87, 70, 56, 45,
1376 /* 15 */ 36, 29, 23, 18, 15,
1377 };
1378
1379 /*
1380 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
1381 *
1382 * In cases where the weight does not change often, we can use the
1383 * precalculated inverse to speed up arithmetics by turning divisions
1384 * into multiplications:
1385 */
1386 static const u32 prio_to_wmult[40] = {
1387 /* -20 */ 48388, 59856, 76040, 92818, 118348,
1388 /* -15 */ 147320, 184698, 229616, 287308, 360437,
1389 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
1390 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
1391 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
1392 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
1393 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
1394 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
1395 };
1396
1397 static void activate_task(struct rq *rq, struct task_struct *p, int wakeup);
1398
1399 /*
1400 * runqueue iterator, to support SMP load-balancing between different
1401 * scheduling classes, without having to expose their internal data
1402 * structures to the load-balancing proper:
1403 */
1404 struct rq_iterator {
1405 void *arg;
1406 struct task_struct *(*start)(void *);
1407 struct task_struct *(*next)(void *);
1408 };
1409
1410 #ifdef CONFIG_SMP
1411 static unsigned long
1412 balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
1413 unsigned long max_load_move, struct sched_domain *sd,
1414 enum cpu_idle_type idle, int *all_pinned,
1415 int *this_best_prio, struct rq_iterator *iterator);
1416
1417 static int
1418 iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
1419 struct sched_domain *sd, enum cpu_idle_type idle,
1420 struct rq_iterator *iterator);
1421 #endif
1422
1423 /* Time spent by the tasks of the cpu accounting group executing in ... */
1424 enum cpuacct_stat_index {
1425 CPUACCT_STAT_USER, /* ... user mode */
1426 CPUACCT_STAT_SYSTEM, /* ... kernel mode */
1427
1428 CPUACCT_STAT_NSTATS,
1429 };
1430
1431 #ifdef CONFIG_CGROUP_CPUACCT
1432 static void cpuacct_charge(struct task_struct *tsk, u64 cputime);
1433 static void cpuacct_update_stats(struct task_struct *tsk,
1434 enum cpuacct_stat_index idx, cputime_t val);
1435 #else
1436 static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {}
1437 static inline void cpuacct_update_stats(struct task_struct *tsk,
1438 enum cpuacct_stat_index idx, cputime_t val) {}
1439 #endif
1440
1441 static inline void inc_cpu_load(struct rq *rq, unsigned long load)
1442 {
1443 update_load_add(&rq->load, load);
1444 }
1445
1446 static inline void dec_cpu_load(struct rq *rq, unsigned long load)
1447 {
1448 update_load_sub(&rq->load, load);
1449 }
1450
1451 #if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) || defined(CONFIG_RT_GROUP_SCHED)
1452 typedef int (*tg_visitor)(struct task_group *, void *);
1453
1454 /*
1455 * Iterate the full tree, calling @down when first entering a node and @up when
1456 * leaving it for the final time.
1457 */
1458 static int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
1459 {
1460 struct task_group *parent, *child;
1461 int ret;
1462
1463 rcu_read_lock();
1464 parent = &root_task_group;
1465 down:
1466 ret = (*down)(parent, data);
1467 if (ret)
1468 goto out_unlock;
1469 list_for_each_entry_rcu(child, &parent->children, siblings) {
1470 parent = child;
1471 goto down;
1472
1473 up:
1474 continue;
1475 }
1476 ret = (*up)(parent, data);
1477 if (ret)
1478 goto out_unlock;
1479
1480 child = parent;
1481 parent = parent->parent;
1482 if (parent)
1483 goto up;
1484 out_unlock:
1485 rcu_read_unlock();
1486
1487 return ret;
1488 }
1489
1490 static int tg_nop(struct task_group *tg, void *data)
1491 {
1492 return 0;
1493 }
1494 #endif
1495
1496 #ifdef CONFIG_SMP
1497 static unsigned long source_load(int cpu, int type);
1498 static unsigned long target_load(int cpu, int type);
1499 static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
1500
1501 static unsigned long cpu_avg_load_per_task(int cpu)
1502 {
1503 struct rq *rq = cpu_rq(cpu);
1504 unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
1505
1506 if (nr_running)
1507 rq->avg_load_per_task = rq->load.weight / nr_running;
1508 else
1509 rq->avg_load_per_task = 0;
1510
1511 return rq->avg_load_per_task;
1512 }
1513
1514 #ifdef CONFIG_FAIR_GROUP_SCHED
1515
1516 static void __set_se_shares(struct sched_entity *se, unsigned long shares);
1517
1518 /*
1519 * Calculate and set the cpu's group shares.
1520 */
1521 static void
1522 update_group_shares_cpu(struct task_group *tg, int cpu,
1523 unsigned long sd_shares, unsigned long sd_rq_weight)
1524 {
1525 unsigned long shares;
1526 unsigned long rq_weight;
1527
1528 if (!tg->se[cpu])
1529 return;
1530
1531 rq_weight = tg->cfs_rq[cpu]->rq_weight;
1532
1533 /*
1534 * \Sum shares * rq_weight
1535 * shares = -----------------------
1536 * \Sum rq_weight
1537 *
1538 */
1539 shares = (sd_shares * rq_weight) / sd_rq_weight;
1540 shares = clamp_t(unsigned long, shares, MIN_SHARES, MAX_SHARES);
1541
1542 if (abs(shares - tg->se[cpu]->load.weight) >
1543 sysctl_sched_shares_thresh) {
1544 struct rq *rq = cpu_rq(cpu);
1545 unsigned long flags;
1546
1547 spin_lock_irqsave(&rq->lock, flags);
1548 tg->cfs_rq[cpu]->shares = shares;
1549
1550 __set_se_shares(tg->se[cpu], shares);
1551 spin_unlock_irqrestore(&rq->lock, flags);
1552 }
1553 }
1554
1555 /*
1556 * Re-compute the task group their per cpu shares over the given domain.
1557 * This needs to be done in a bottom-up fashion because the rq weight of a
1558 * parent group depends on the shares of its child groups.
1559 */
1560 static int tg_shares_up(struct task_group *tg, void *data)
1561 {
1562 unsigned long weight, rq_weight = 0;
1563 unsigned long shares = 0;
1564 struct sched_domain *sd = data;
1565 int i;
1566
1567 for_each_cpu(i, sched_domain_span(sd)) {
1568 /*
1569 * If there are currently no tasks on the cpu pretend there
1570 * is one of average load so that when a new task gets to
1571 * run here it will not get delayed by group starvation.
1572 */
1573 weight = tg->cfs_rq[i]->load.weight;
1574 if (!weight)
1575 weight = NICE_0_LOAD;
1576
1577 tg->cfs_rq[i]->rq_weight = weight;
1578 rq_weight += weight;
1579 shares += tg->cfs_rq[i]->shares;
1580 }
1581
1582 if ((!shares && rq_weight) || shares > tg->shares)
1583 shares = tg->shares;
1584
1585 if (!sd->parent || !(sd->parent->flags & SD_LOAD_BALANCE))
1586 shares = tg->shares;
1587
1588 for_each_cpu(i, sched_domain_span(sd))
1589 update_group_shares_cpu(tg, i, shares, rq_weight);
1590
1591 return 0;
1592 }
1593
1594 /*
1595 * Compute the cpu's hierarchical load factor for each task group.
1596 * This needs to be done in a top-down fashion because the load of a child
1597 * group is a fraction of its parents load.
1598 */
1599 static int tg_load_down(struct task_group *tg, void *data)
1600 {
1601 unsigned long load;
1602 long cpu = (long)data;
1603
1604 if (!tg->parent) {
1605 load = cpu_rq(cpu)->load.weight;
1606 } else {
1607 load = tg->parent->cfs_rq[cpu]->h_load;
1608 load *= tg->cfs_rq[cpu]->shares;
1609 load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
1610 }
1611
1612 tg->cfs_rq[cpu]->h_load = load;
1613
1614 return 0;
1615 }
1616
1617 static void update_shares(struct sched_domain *sd)
1618 {
1619 u64 now = cpu_clock(raw_smp_processor_id());
1620 s64 elapsed = now - sd->last_update;
1621
1622 if (elapsed >= (s64)(u64)sysctl_sched_shares_ratelimit) {
1623 sd->last_update = now;
1624 walk_tg_tree(tg_nop, tg_shares_up, sd);
1625 }
1626 }
1627
1628 static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
1629 {
1630 spin_unlock(&rq->lock);
1631 update_shares(sd);
1632 spin_lock(&rq->lock);
1633 }
1634
1635 static void update_h_load(long cpu)
1636 {
1637 walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
1638 }
1639
1640 #else
1641
1642 static inline void update_shares(struct sched_domain *sd)
1643 {
1644 }
1645
1646 static inline void update_shares_locked(struct rq *rq, struct sched_domain *sd)
1647 {
1648 }
1649
1650 #endif
1651
1652 #ifdef CONFIG_PREEMPT
1653
1654 /*
1655 * fair double_lock_balance: Safely acquires both rq->locks in a fair
1656 * way at the expense of forcing extra atomic operations in all
1657 * invocations. This assures that the double_lock is acquired using the
1658 * same underlying policy as the spinlock_t on this architecture, which
1659 * reduces latency compared to the unfair variant below. However, it
1660 * also adds more overhead and therefore may reduce throughput.
1661 */
1662 static inline int _double_lock_balance(struct rq *this_rq, struct rq *busiest)
1663 __releases(this_rq->lock)
1664 __acquires(busiest->lock)
1665 __acquires(this_rq->lock)
1666 {
1667 spin_unlock(&this_rq->lock);
1668 double_rq_lock(this_rq, busiest);
1669
1670 return 1;
1671 }
1672
1673 #else
1674 /*
1675 * Unfair double_lock_balance: Optimizes throughput at the expense of
1676 * latency by eliminating extra atomic operations when the locks are
1677 * already in proper order on entry. This favors lower cpu-ids and will
1678 * grant the double lock to lower cpus over higher ids under contention,
1679 * regardless of entry order into the function.
1680 */
1681 static int _double_lock_balance(struct rq *this_rq, struct rq *busiest)
1682 __releases(this_rq->lock)
1683 __acquires(busiest->lock)
1684 __acquires(this_rq->lock)
1685 {
1686 int ret = 0;
1687
1688 if (unlikely(!spin_trylock(&busiest->lock))) {
1689 if (busiest < this_rq) {
1690 spin_unlock(&this_rq->lock);
1691 spin_lock(&busiest->lock);
1692 spin_lock_nested(&this_rq->lock, SINGLE_DEPTH_NESTING);
1693 ret = 1;
1694 } else
1695 spin_lock_nested(&busiest->lock, SINGLE_DEPTH_NESTING);
1696 }
1697 return ret;
1698 }
1699
1700 #endif /* CONFIG_PREEMPT */
1701
1702 /*
1703 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1704 */
1705 static int double_lock_balance(struct rq *this_rq, struct rq *busiest)
1706 {
1707 if (unlikely(!irqs_disabled())) {
1708 /* printk() doesn't work good under rq->lock */
1709 spin_unlock(&this_rq->lock);
1710 BUG_ON(1);
1711 }
1712
1713 return _double_lock_balance(this_rq, busiest);
1714 }
1715
1716 static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest)
1717 __releases(busiest->lock)
1718 {
1719 spin_unlock(&busiest->lock);
1720 lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_);
1721 }
1722 #endif
1723
1724 #ifdef CONFIG_FAIR_GROUP_SCHED
1725 static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares)
1726 {
1727 #ifdef CONFIG_SMP
1728 cfs_rq->shares = shares;
1729 #endif
1730 }
1731 #endif
1732
1733 static void calc_load_account_active(struct rq *this_rq);
1734
1735 #include "sched_stats.h"
1736 #include "sched_idletask.c"
1737 #include "sched_fair.c"
1738 #include "sched_rt.c"
1739 #ifdef CONFIG_SCHED_DEBUG
1740 # include "sched_debug.c"
1741 #endif
1742
1743 #define sched_class_highest (&rt_sched_class)
1744 #define for_each_class(class) \
1745 for (class = sched_class_highest; class; class = class->next)
1746
1747 static void inc_nr_running(struct rq *rq)
1748 {
1749 rq->nr_running++;
1750 }
1751
1752 static void dec_nr_running(struct rq *rq)
1753 {
1754 rq->nr_running--;
1755 }
1756
1757 static void set_load_weight(struct task_struct *p)
1758 {
1759 if (task_has_rt_policy(p)) {
1760 p->se.load.weight = prio_to_weight[0] * 2;
1761 p->se.load.inv_weight = prio_to_wmult[0] >> 1;
1762 return;
1763 }
1764
1765 /*
1766 * SCHED_IDLE tasks get minimal weight:
1767 */
1768 if (p->policy == SCHED_IDLE) {
1769 p->se.load.weight = WEIGHT_IDLEPRIO;
1770 p->se.load.inv_weight = WMULT_IDLEPRIO;
1771 return;
1772 }
1773
1774 p->se.load.weight = prio_to_weight[p->static_prio - MAX_RT_PRIO];
1775 p->se.load.inv_weight = prio_to_wmult[p->static_prio - MAX_RT_PRIO];
1776 }
1777
1778 static void update_avg(u64 *avg, u64 sample)
1779 {
1780 s64 diff = sample - *avg;
1781 *avg += diff >> 3;
1782 }
1783
1784 static void enqueue_task(struct rq *rq, struct task_struct *p, int wakeup)
1785 {
1786 if (wakeup)
1787 p->se.start_runtime = p->se.sum_exec_runtime;
1788
1789 sched_info_queued(p);
1790 p->sched_class->enqueue_task(rq, p, wakeup);
1791 p->se.on_rq = 1;
1792 }
1793
1794 static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep)
1795 {
1796 if (sleep) {
1797 if (p->se.last_wakeup) {
1798 update_avg(&p->se.avg_overlap,
1799 p->se.sum_exec_runtime - p->se.last_wakeup);
1800 p->se.last_wakeup = 0;
1801 } else {
1802 update_avg(&p->se.avg_wakeup,
1803 sysctl_sched_wakeup_granularity);
1804 }
1805 }
1806
1807 sched_info_dequeued(p);
1808 p->sched_class->dequeue_task(rq, p, sleep);
1809 p->se.on_rq = 0;
1810 }
1811
1812 /*
1813 * __normal_prio - return the priority that is based on the static prio
1814 */
1815 static inline int __normal_prio(struct task_struct *p)
1816 {
1817 return p->static_prio;
1818 }
1819
1820 /*
1821 * Calculate the expected normal priority: i.e. priority
1822 * without taking RT-inheritance into account. Might be
1823 * boosted by interactivity modifiers. Changes upon fork,
1824 * setprio syscalls, and whenever the interactivity
1825 * estimator recalculates.
1826 */
1827 static inline int normal_prio(struct task_struct *p)
1828 {
1829 int prio;
1830
1831 if (task_has_rt_policy(p))
1832 prio = MAX_RT_PRIO-1 - p->rt_priority;
1833 else
1834 prio = __normal_prio(p);
1835 return prio;
1836 }
1837
1838 /*
1839 * Calculate the current priority, i.e. the priority
1840 * taken into account by the scheduler. This value might
1841 * be boosted by RT tasks, or might be boosted by
1842 * interactivity modifiers. Will be RT if the task got
1843 * RT-boosted. If not then it returns p->normal_prio.
1844 */
1845 static int effective_prio(struct task_struct *p)
1846 {
1847 p->normal_prio = normal_prio(p);
1848 /*
1849 * If we are RT tasks or we were boosted to RT priority,
1850 * keep the priority unchanged. Otherwise, update priority
1851 * to the normal priority:
1852 */
1853 if (!rt_prio(p->prio))
1854 return p->normal_prio;
1855 return p->prio;
1856 }
1857
1858 /*
1859 * activate_task - move a task to the runqueue.
1860 */
1861 static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
1862 {
1863 if (task_contributes_to_load(p))
1864 rq->nr_uninterruptible--;
1865
1866 enqueue_task(rq, p, wakeup);
1867 inc_nr_running(rq);
1868 }
1869
1870 /*
1871 * deactivate_task - remove a task from the runqueue.
1872 */
1873 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
1874 {
1875 if (task_contributes_to_load(p))
1876 rq->nr_uninterruptible++;
1877
1878 dequeue_task(rq, p, sleep);
1879 dec_nr_running(rq);
1880 }
1881
1882 /**
1883 * task_curr - is this task currently executing on a CPU?
1884 * @p: the task in question.
1885 */
1886 inline int task_curr(const struct task_struct *p)
1887 {
1888 return cpu_curr(task_cpu(p)) == p;
1889 }
1890
1891 static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
1892 {
1893 set_task_rq(p, cpu);
1894 #ifdef CONFIG_SMP
1895 /*
1896 * After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
1897 * successfuly executed on another CPU. We must ensure that updates of
1898 * per-task data have been completed by this moment.
1899 */
1900 smp_wmb();
1901 task_thread_info(p)->cpu = cpu;
1902 #endif
1903 }
1904
1905 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
1906 const struct sched_class *prev_class,
1907 int oldprio, int running)
1908 {
1909 if (prev_class != p->sched_class) {
1910 if (prev_class->switched_from)
1911 prev_class->switched_from(rq, p, running);
1912 p->sched_class->switched_to(rq, p, running);
1913 } else
1914 p->sched_class->prio_changed(rq, p, oldprio, running);
1915 }
1916
1917 #ifdef CONFIG_SMP
1918
1919 /* Used instead of source_load when we know the type == 0 */
1920 static unsigned long weighted_cpuload(const int cpu)
1921 {
1922 return cpu_rq(cpu)->load.weight;
1923 }
1924
1925 /*
1926 * Is this task likely cache-hot:
1927 */
1928 static int
1929 task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
1930 {
1931 s64 delta;
1932
1933 /*
1934 * Buddy candidates are cache hot:
1935 */
1936 if (sched_feat(CACHE_HOT_BUDDY) &&
1937 (&p->se == cfs_rq_of(&p->se)->next ||
1938 &p->se == cfs_rq_of(&p->se)->last))
1939 return 1;
1940
1941 if (p->sched_class != &fair_sched_class)
1942 return 0;
1943
1944 if (sysctl_sched_migration_cost == -1)
1945 return 1;
1946 if (sysctl_sched_migration_cost == 0)
1947 return 0;
1948
1949 delta = now - p->se.exec_start;
1950
1951 return delta < (s64)sysctl_sched_migration_cost;
1952 }
1953
1954
1955 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1956 {
1957 int old_cpu = task_cpu(p);
1958 struct rq *old_rq = cpu_rq(old_cpu), *new_rq = cpu_rq(new_cpu);
1959 struct cfs_rq *old_cfsrq = task_cfs_rq(p),
1960 *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu);
1961 u64 clock_offset;
1962
1963 clock_offset = old_rq->clock - new_rq->clock;
1964
1965 trace_sched_migrate_task(p, new_cpu);
1966
1967 #ifdef CONFIG_SCHEDSTATS
1968 if (p->se.wait_start)
1969 p->se.wait_start -= clock_offset;
1970 if (p->se.sleep_start)
1971 p->se.sleep_start -= clock_offset;
1972 if (p->se.block_start)
1973 p->se.block_start -= clock_offset;
1974 #endif
1975 if (old_cpu != new_cpu) {
1976 p->se.nr_migrations++;
1977 new_rq->nr_migrations_in++;
1978 #ifdef CONFIG_SCHEDSTATS
1979 if (task_hot(p, old_rq->clock, NULL))
1980 schedstat_inc(p, se.nr_forced2_migrations);
1981 #endif
1982 perf_swcounter_event(PERF_COUNT_SW_CPU_MIGRATIONS,
1983 1, 1, NULL, 0);
1984 }
1985 p->se.vruntime -= old_cfsrq->min_vruntime -
1986 new_cfsrq->min_vruntime;
1987
1988 __set_task_cpu(p, new_cpu);
1989 }
1990
1991 struct migration_req {
1992 struct list_head list;
1993
1994 struct task_struct *task;
1995 int dest_cpu;
1996
1997 struct completion done;
1998 };
1999
2000 /*
2001 * The task's runqueue lock must be held.
2002 * Returns true if you have to wait for migration thread.
2003 */
2004 static int
2005 migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
2006 {
2007 struct rq *rq = task_rq(p);
2008
2009 /*
2010 * If the task is not on a runqueue (and not running), then
2011 * it is sufficient to simply update the task's cpu field.
2012 */
2013 if (!p->se.on_rq && !task_running(rq, p)) {
2014 set_task_cpu(p, dest_cpu);
2015 return 0;
2016 }
2017
2018 init_completion(&req->done);
2019 req->task = p;
2020 req->dest_cpu = dest_cpu;
2021 list_add(&req->list, &rq->migration_queue);
2022
2023 return 1;
2024 }
2025
2026 /*
2027 * wait_task_context_switch - wait for a thread to complete at least one
2028 * context switch.
2029 *
2030 * @p must not be current.
2031 */
2032 void wait_task_context_switch(struct task_struct *p)
2033 {
2034 unsigned long nvcsw, nivcsw, flags;
2035 int running;
2036 struct rq *rq;
2037
2038 nvcsw = p->nvcsw;
2039 nivcsw = p->nivcsw;
2040 for (;;) {
2041 /*
2042 * The runqueue is assigned before the actual context
2043 * switch. We need to take the runqueue lock.
2044 *
2045 * We could check initially without the lock but it is
2046 * very likely that we need to take the lock in every
2047 * iteration.
2048 */
2049 rq = task_rq_lock(p, &flags);
2050 running = task_running(rq, p);
2051 task_rq_unlock(rq, &flags);
2052
2053 if (likely(!running))
2054 break;
2055 /*
2056 * The switch count is incremented before the actual
2057 * context switch. We thus wait for two switches to be
2058 * sure at least one completed.
2059 */
2060 if ((p->nvcsw - nvcsw) > 1)
2061 break;
2062 if ((p->nivcsw - nivcsw) > 1)
2063 break;
2064
2065 cpu_relax();
2066 }
2067 }
2068
2069 /*
2070 * wait_task_inactive - wait for a thread to unschedule.
2071 *
2072 * If @match_state is nonzero, it's the @p->state value just checked and
2073 * not expected to change. If it changes, i.e. @p might have woken up,
2074 * then return zero. When we succeed in waiting for @p to be off its CPU,
2075 * we return a positive number (its total switch count). If a second call
2076 * a short while later returns the same number, the caller can be sure that
2077 * @p has remained unscheduled the whole time.
2078 *
2079 * The caller must ensure that the task *will* unschedule sometime soon,
2080 * else this function might spin for a *long* time. This function can't
2081 * be called with interrupts off, or it may introduce deadlock with
2082 * smp_call_function() if an IPI is sent by the same process we are
2083 * waiting to become inactive.
2084 */
2085 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
2086 {
2087 unsigned long flags;
2088 int running, on_rq;
2089 unsigned long ncsw;
2090 struct rq *rq;
2091
2092 for (;;) {
2093 /*
2094 * We do the initial early heuristics without holding
2095 * any task-queue locks at all. We'll only try to get
2096 * the runqueue lock when things look like they will
2097 * work out!
2098 */
2099 rq = task_rq(p);
2100
2101 /*
2102 * If the task is actively running on another CPU
2103 * still, just relax and busy-wait without holding
2104 * any locks.
2105 *
2106 * NOTE! Since we don't hold any locks, it's not
2107 * even sure that "rq" stays as the right runqueue!
2108 * But we don't care, since "task_running()" will
2109 * return false if the runqueue has changed and p
2110 * is actually now running somewhere else!
2111 */
2112 while (task_running(rq, p)) {
2113 if (match_state && unlikely(p->state != match_state))
2114 return 0;
2115 cpu_relax();
2116 }
2117
2118 /*
2119 * Ok, time to look more closely! We need the rq
2120 * lock now, to be *sure*. If we're wrong, we'll
2121 * just go back and repeat.
2122 */
2123 rq = task_rq_lock(p, &flags);
2124 trace_sched_wait_task(rq, p);
2125 running = task_running(rq, p);
2126 on_rq = p->se.on_rq;
2127 ncsw = 0;
2128 if (!match_state || p->state == match_state)
2129 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
2130 task_rq_unlock(rq, &flags);
2131
2132 /*
2133 * If it changed from the expected state, bail out now.
2134 */
2135 if (unlikely(!ncsw))
2136 break;
2137
2138 /*
2139 * Was it really running after all now that we
2140 * checked with the proper locks actually held?
2141 *
2142 * Oops. Go back and try again..
2143 */
2144 if (unlikely(running)) {
2145 cpu_relax();
2146 continue;
2147 }
2148
2149 /*
2150 * It's not enough that it's not actively running,
2151 * it must be off the runqueue _entirely_, and not
2152 * preempted!
2153 *
2154 * So if it was still runnable (but just not actively
2155 * running right now), it's preempted, and we should
2156 * yield - it could be a while.
2157 */
2158 if (unlikely(on_rq)) {
2159 schedule_timeout_uninterruptible(1);
2160 continue;
2161 }
2162
2163 /*
2164 * Ahh, all good. It wasn't running, and it wasn't
2165 * runnable, which means that it will never become
2166 * running in the future either. We're all done!
2167 */
2168 break;
2169 }
2170
2171 return ncsw;
2172 }
2173
2174 /***
2175 * kick_process - kick a running thread to enter/exit the kernel
2176 * @p: the to-be-kicked thread
2177 *
2178 * Cause a process which is running on another CPU to enter
2179 * kernel-mode, without any delay. (to get signals handled.)
2180 *
2181 * NOTE: this function doesnt have to take the runqueue lock,
2182 * because all it wants to ensure is that the remote task enters
2183 * the kernel. If the IPI races and the task has been migrated
2184 * to another CPU then no harm is done and the purpose has been
2185 * achieved as well.
2186 */
2187 void kick_process(struct task_struct *p)
2188 {
2189 int cpu;
2190
2191 preempt_disable();
2192 cpu = task_cpu(p);
2193 if ((cpu != smp_processor_id()) && task_curr(p))
2194 smp_send_reschedule(cpu);
2195 preempt_enable();
2196 }
2197 EXPORT_SYMBOL_GPL(kick_process);
2198
2199 /*
2200 * Return a low guess at the load of a migration-source cpu weighted
2201 * according to the scheduling class and "nice" value.
2202 *
2203 * We want to under-estimate the load of migration sources, to
2204 * balance conservatively.
2205 */
2206 static unsigned long source_load(int cpu, int type)
2207 {
2208 struct rq *rq = cpu_rq(cpu);
2209 unsigned long total = weighted_cpuload(cpu);
2210
2211 if (type == 0 || !sched_feat(LB_BIAS))
2212 return total;
2213
2214 return min(rq->cpu_load[type-1], total);
2215 }
2216
2217 /*
2218 * Return a high guess at the load of a migration-target cpu weighted
2219 * according to the scheduling class and "nice" value.
2220 */
2221 static unsigned long target_load(int cpu, int type)
2222 {
2223 struct rq *rq = cpu_rq(cpu);
2224 unsigned long total = weighted_cpuload(cpu);
2225
2226 if (type == 0 || !sched_feat(LB_BIAS))
2227 return total;
2228
2229 return max(rq->cpu_load[type-1], total);
2230 }
2231
2232 /*
2233 * find_idlest_group finds and returns the least busy CPU group within the
2234 * domain.
2235 */
2236 static struct sched_group *
2237 find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
2238 {
2239 struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
2240 unsigned long min_load = ULONG_MAX, this_load = 0;
2241 int load_idx = sd->forkexec_idx;
2242 int imbalance = 100 + (sd->imbalance_pct-100)/2;
2243
2244 do {
2245 unsigned long load, avg_load;
2246 int local_group;
2247 int i;
2248
2249 /* Skip over this group if it has no CPUs allowed */
2250 if (!cpumask_intersects(sched_group_cpus(group),
2251 &p->cpus_allowed))
2252 continue;
2253
2254 local_group = cpumask_test_cpu(this_cpu,
2255 sched_group_cpus(group));
2256
2257 /* Tally up the load of all CPUs in the group */
2258 avg_load = 0;
2259
2260 for_each_cpu(i, sched_group_cpus(group)) {
2261 /* Bias balancing toward cpus of our domain */
2262 if (local_group)
2263 load = source_load(i, load_idx);
2264 else
2265 load = target_load(i, load_idx);
2266
2267 avg_load += load;
2268 }
2269
2270 /* Adjust by relative CPU power of the group */
2271 avg_load = sg_div_cpu_power(group,
2272 avg_load * SCHED_LOAD_SCALE);
2273
2274 if (local_group) {
2275 this_load = avg_load;
2276 this = group;
2277 } else if (avg_load < min_load) {
2278 min_load = avg_load;
2279 idlest = group;
2280 }
2281 } while (group = group->next, group != sd->groups);
2282
2283 if (!idlest || 100*this_load < imbalance*min_load)
2284 return NULL;
2285 return idlest;
2286 }
2287
2288 /*
2289 * find_idlest_cpu - find the idlest cpu among the cpus in group.
2290 */
2291 static int
2292 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
2293 {
2294 unsigned long load, min_load = ULONG_MAX;
2295 int idlest = -1;
2296 int i;
2297
2298 /* Traverse only the allowed CPUs */
2299 for_each_cpu_and(i, sched_group_cpus(group), &p->cpus_allowed) {
2300 load = weighted_cpuload(i);
2301
2302 if (load < min_load || (load == min_load && i == this_cpu)) {
2303 min_load = load;
2304 idlest = i;
2305 }
2306 }
2307
2308 return idlest;
2309 }
2310
2311 /*
2312 * sched_balance_self: balance the current task (running on cpu) in domains
2313 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
2314 * SD_BALANCE_EXEC.
2315 *
2316 * Balance, ie. select the least loaded group.
2317 *
2318 * Returns the target CPU number, or the same CPU if no balancing is needed.
2319 *
2320 * preempt must be disabled.
2321 */
2322 static int sched_balance_self(int cpu, int flag)
2323 {
2324 struct task_struct *t = current;
2325 struct sched_domain *tmp, *sd = NULL;
2326
2327 for_each_domain(cpu, tmp) {
2328 /*
2329 * If power savings logic is enabled for a domain, stop there.
2330 */
2331 if (tmp->flags & SD_POWERSAVINGS_BALANCE)
2332 break;
2333 if (tmp->flags & flag)
2334 sd = tmp;
2335 }
2336
2337 if (sd)
2338 update_shares(sd);
2339
2340 while (sd) {
2341 struct sched_group *group;
2342 int new_cpu, weight;
2343
2344 if (!(sd->flags & flag)) {
2345 sd = sd->child;
2346 continue;
2347 }
2348
2349 group = find_idlest_group(sd, t, cpu);
2350 if (!group) {
2351 sd = sd->child;
2352 continue;
2353 }
2354
2355 new_cpu = find_idlest_cpu(group, t, cpu);
2356 if (new_cpu == -1 || new_cpu == cpu) {
2357 /* Now try balancing at a lower domain level of cpu */
2358 sd = sd->child;
2359 continue;
2360 }
2361
2362 /* Now try balancing at a lower domain level of new_cpu */
2363 cpu = new_cpu;
2364 weight = cpumask_weight(sched_domain_span(sd));
2365 sd = NULL;
2366 for_each_domain(cpu, tmp) {
2367 if (weight <= cpumask_weight(sched_domain_span(tmp)))
2368 break;
2369 if (tmp->flags & flag)
2370 sd = tmp;
2371 }
2372 /* while loop will break here if sd == NULL */
2373 }
2374
2375 return cpu;
2376 }
2377
2378 #endif /* CONFIG_SMP */
2379
2380 /**
2381 * task_oncpu_function_call - call a function on the cpu on which a task runs
2382 * @p: the task to evaluate
2383 * @func: the function to be called
2384 * @info: the function call argument
2385 *
2386 * Calls the function @func when the task is currently running. This might
2387 * be on the current CPU, which just calls the function directly
2388 */
2389 void task_oncpu_function_call(struct task_struct *p,
2390 void (*func) (void *info), void *info)
2391 {
2392 int cpu;
2393
2394 preempt_disable();
2395 cpu = task_cpu(p);
2396 if (task_curr(p))
2397 smp_call_function_single(cpu, func, info, 1);
2398 preempt_enable();
2399 }
2400
2401 /***
2402 * try_to_wake_up - wake up a thread
2403 * @p: the to-be-woken-up thread
2404 * @state: the mask of task states that can be woken
2405 * @sync: do a synchronous wakeup?
2406 *
2407 * Put it on the run-queue if it's not already there. The "current"
2408 * thread is always on the run-queue (except when the actual
2409 * re-schedule is in progress), and as such you're allowed to do
2410 * the simpler "current->state = TASK_RUNNING" to mark yourself
2411 * runnable without the overhead of this.
2412 *
2413 * returns failure only if the task is already active.
2414 */
2415 static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
2416 {
2417 int cpu, orig_cpu, this_cpu, success = 0;
2418 unsigned long flags;
2419 long old_state;
2420 struct rq *rq;
2421
2422 if (!sched_feat(SYNC_WAKEUPS))
2423 sync = 0;
2424
2425 #ifdef CONFIG_SMP
2426 if (sched_feat(LB_WAKEUP_UPDATE) && !root_task_group_empty()) {
2427 struct sched_domain *sd;
2428
2429 this_cpu = raw_smp_processor_id();
2430 cpu = task_cpu(p);
2431
2432 for_each_domain(this_cpu, sd) {
2433 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
2434 update_shares(sd);
2435 break;
2436 }
2437 }
2438 }
2439 #endif
2440
2441 smp_wmb();
2442 rq = task_rq_lock(p, &flags);
2443 update_rq_clock(rq);
2444 old_state = p->state;
2445 if (!(old_state & state))
2446 goto out;
2447
2448 if (p->se.on_rq)
2449 goto out_running;
2450
2451 cpu = task_cpu(p);
2452 orig_cpu = cpu;
2453 this_cpu = smp_processor_id();
2454
2455 #ifdef CONFIG_SMP
2456 if (unlikely(task_running(rq, p)))
2457 goto out_activate;
2458
2459 cpu = p->sched_class->select_task_rq(p, sync);
2460 if (cpu != orig_cpu) {
2461 set_task_cpu(p, cpu);
2462 task_rq_unlock(rq, &flags);
2463 /* might preempt at this point */
2464 rq = task_rq_lock(p, &flags);
2465 old_state = p->state;
2466 if (!(old_state & state))
2467 goto out;
2468 if (p->se.on_rq)
2469 goto out_running;
2470
2471 this_cpu = smp_processor_id();
2472 cpu = task_cpu(p);
2473 }
2474
2475 #ifdef CONFIG_SCHEDSTATS
2476 schedstat_inc(rq, ttwu_count);
2477 if (cpu == this_cpu)
2478 schedstat_inc(rq, ttwu_local);
2479 else {
2480 struct sched_domain *sd;
2481 for_each_domain(this_cpu, sd) {
2482 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
2483 schedstat_inc(sd, ttwu_wake_remote);
2484 break;
2485 }
2486 }
2487 }
2488 #endif /* CONFIG_SCHEDSTATS */
2489
2490 out_activate:
2491 #endif /* CONFIG_SMP */
2492 schedstat_inc(p, se.nr_wakeups);
2493 if (sync)
2494 schedstat_inc(p, se.nr_wakeups_sync);
2495 if (orig_cpu != cpu)
2496 schedstat_inc(p, se.nr_wakeups_migrate);
2497 if (cpu == this_cpu)
2498 schedstat_inc(p, se.nr_wakeups_local);
2499 else
2500 schedstat_inc(p, se.nr_wakeups_remote);
2501 activate_task(rq, p, 1);
2502 success = 1;
2503
2504 /*
2505 * Only attribute actual wakeups done by this task.
2506 */
2507 if (!in_interrupt()) {
2508 struct sched_entity *se = &current->se;
2509 u64 sample = se->sum_exec_runtime;
2510
2511 if (se->last_wakeup)
2512 sample -= se->last_wakeup;
2513 else
2514 sample -= se->start_runtime;
2515 update_avg(&se->avg_wakeup, sample);
2516
2517 se->last_wakeup = se->sum_exec_runtime;
2518 }
2519
2520 out_running:
2521 trace_sched_wakeup(rq, p, success);
2522 check_preempt_curr(rq, p, sync);
2523
2524 p->state = TASK_RUNNING;
2525 #ifdef CONFIG_SMP
2526 if (p->sched_class->task_wake_up)
2527 p->sched_class->task_wake_up(rq, p);
2528 #endif
2529 out:
2530 task_rq_unlock(rq, &flags);
2531
2532 return success;
2533 }
2534
2535 /**
2536 * wake_up_process - Wake up a specific process
2537 * @p: The process to be woken up.
2538 *
2539 * Attempt to wake up the nominated process and move it to the set of runnable
2540 * processes. Returns 1 if the process was woken up, 0 if it was already
2541 * running.
2542 *
2543 * It may be assumed that this function implies a write memory barrier before
2544 * changing the task state if and only if any tasks are woken up.
2545 */
2546 int wake_up_process(struct task_struct *p)
2547 {
2548 return try_to_wake_up(p, TASK_ALL, 0);
2549 }
2550 EXPORT_SYMBOL(wake_up_process);
2551
2552 int wake_up_state(struct task_struct *p, unsigned int state)
2553 {
2554 return try_to_wake_up(p, state, 0);
2555 }
2556
2557 /*
2558 * Perform scheduler related setup for a newly forked process p.
2559 * p is forked by current.
2560 *
2561 * __sched_fork() is basic setup used by init_idle() too:
2562 */
2563 static void __sched_fork(struct task_struct *p)
2564 {
2565 p->se.exec_start = 0;
2566 p->se.sum_exec_runtime = 0;
2567 p->se.prev_sum_exec_runtime = 0;
2568 p->se.nr_migrations = 0;
2569 p->se.last_wakeup = 0;
2570 p->se.avg_overlap = 0;
2571 p->se.start_runtime = 0;
2572 p->se.avg_wakeup = sysctl_sched_wakeup_granularity;
2573
2574 #ifdef CONFIG_SCHEDSTATS
2575 p->se.wait_start = 0;
2576 p->se.wait_max = 0;
2577 p->se.wait_count = 0;
2578 p->se.wait_sum = 0;
2579
2580 p->se.sleep_start = 0;
2581 p->se.sleep_max = 0;
2582 p->se.sum_sleep_runtime = 0;
2583
2584 p->se.block_start = 0;
2585 p->se.block_max = 0;
2586 p->se.exec_max = 0;
2587 p->se.slice_max = 0;
2588
2589 p->se.nr_migrations_cold = 0;
2590 p->se.nr_failed_migrations_affine = 0;
2591 p->se.nr_failed_migrations_running = 0;
2592 p->se.nr_failed_migrations_hot = 0;
2593 p->se.nr_forced_migrations = 0;
2594 p->se.nr_forced2_migrations = 0;
2595
2596 p->se.nr_wakeups = 0;
2597 p->se.nr_wakeups_sync = 0;
2598 p->se.nr_wakeups_migrate = 0;
2599 p->se.nr_wakeups_local = 0;
2600 p->se.nr_wakeups_remote = 0;
2601 p->se.nr_wakeups_affine = 0;
2602 p->se.nr_wakeups_affine_attempts = 0;
2603 p->se.nr_wakeups_passive = 0;
2604 p->se.nr_wakeups_idle = 0;
2605
2606 #endif
2607
2608 INIT_LIST_HEAD(&p->rt.run_list);
2609 p->se.on_rq = 0;
2610 INIT_LIST_HEAD(&p->se.group_node);
2611
2612 #ifdef CONFIG_PREEMPT_NOTIFIERS
2613 INIT_HLIST_HEAD(&p->preempt_notifiers);
2614 #endif
2615
2616 /*
2617 * We mark the process as running here, but have not actually
2618 * inserted it onto the runqueue yet. This guarantees that
2619 * nobody will actually run it, and a signal or other external
2620 * event cannot wake it up and insert it on the runqueue either.
2621 */
2622 p->state = TASK_RUNNING;
2623 }
2624
2625 /*
2626 * fork()/clone()-time setup:
2627 */
2628 void sched_fork(struct task_struct *p, int clone_flags)
2629 {
2630 int cpu = get_cpu();
2631
2632 __sched_fork(p);
2633
2634 #ifdef CONFIG_SMP
2635 cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
2636 #endif
2637 set_task_cpu(p, cpu);
2638
2639 /*
2640 * Make sure we do not leak PI boosting priority to the child:
2641 */
2642 p->prio = current->normal_prio;
2643 if (!rt_prio(p->prio))
2644 p->sched_class = &fair_sched_class;
2645
2646 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
2647 if (likely(sched_info_on()))
2648 memset(&p->sched_info, 0, sizeof(p->sched_info));
2649 #endif
2650 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
2651 p->oncpu = 0;
2652 #endif
2653 #ifdef CONFIG_PREEMPT
2654 /* Want to start with kernel preemption disabled. */
2655 task_thread_info(p)->preempt_count = 1;
2656 #endif
2657 plist_node_init(&p->pushable_tasks, MAX_PRIO);
2658
2659 put_cpu();
2660 }
2661
2662 /*
2663 * wake_up_new_task - wake up a newly created task for the first time.
2664 *
2665 * This function will do some initial scheduler statistics housekeeping
2666 * that must be done for every newly created context, then puts the task
2667 * on the runqueue and wakes it.
2668 */
2669 void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
2670 {
2671 unsigned long flags;
2672 struct rq *rq;
2673
2674 rq = task_rq_lock(p, &flags);
2675 BUG_ON(p->state != TASK_RUNNING);
2676 update_rq_clock(rq);
2677
2678 p->prio = effective_prio(p);
2679
2680 if (!p->sched_class->task_new || !current->se.on_rq) {
2681 activate_task(rq, p, 0);
2682 } else {
2683 /*
2684 * Let the scheduling class do new task startup
2685 * management (if any):
2686 */
2687 p->sched_class->task_new(rq, p);
2688 inc_nr_running(rq);
2689 }
2690 trace_sched_wakeup_new(rq, p, 1);
2691 check_preempt_curr(rq, p, 0);
2692 #ifdef CONFIG_SMP
2693 if (p->sched_class->task_wake_up)
2694 p->sched_class->task_wake_up(rq, p);
2695 #endif
2696 task_rq_unlock(rq, &flags);
2697 }
2698
2699 #ifdef CONFIG_PREEMPT_NOTIFIERS
2700
2701 /**
2702 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2703 * @notifier: notifier struct to register
2704 */
2705 void preempt_notifier_register(struct preempt_notifier *notifier)
2706 {
2707 hlist_add_head(&notifier->link, &current->preempt_notifiers);
2708 }
2709 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2710
2711 /**
2712 * preempt_notifier_unregister - no longer interested in preemption notifications
2713 * @notifier: notifier struct to unregister
2714 *
2715 * This is safe to call from within a preemption notifier.
2716 */
2717 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2718 {
2719 hlist_del(&notifier->link);
2720 }
2721 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2722
2723 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2724 {
2725 struct preempt_notifier *notifier;
2726 struct hlist_node *node;
2727
2728 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2729 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2730 }
2731
2732 static void
2733 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2734 struct task_struct *next)
2735 {
2736 struct preempt_notifier *notifier;
2737 struct hlist_node *node;
2738
2739 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2740 notifier->ops->sched_out(notifier, next);
2741 }
2742
2743 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2744
2745 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2746 {
2747 }
2748
2749 static void
2750 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2751 struct task_struct *next)
2752 {
2753 }
2754
2755 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2756
2757 /**
2758 * prepare_task_switch - prepare to switch tasks
2759 * @rq: the runqueue preparing to switch
2760 * @prev: the current task that is being switched out
2761 * @next: the task we are going to switch to.
2762 *
2763 * This is called with the rq lock held and interrupts off. It must
2764 * be paired with a subsequent finish_task_switch after the context
2765 * switch.
2766 *
2767 * prepare_task_switch sets up locking and calls architecture specific
2768 * hooks.
2769 */
2770 static inline void
2771 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2772 struct task_struct *next)
2773 {
2774 fire_sched_out_preempt_notifiers(prev, next);
2775 prepare_lock_switch(rq, next);
2776 prepare_arch_switch(next);
2777 }
2778
2779 /**
2780 * finish_task_switch - clean up after a task-switch
2781 * @rq: runqueue associated with task-switch
2782 * @prev: the thread we just switched away from.
2783 *
2784 * finish_task_switch must be called after the context switch, paired
2785 * with a prepare_task_switch call before the context switch.
2786 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2787 * and do any other architecture-specific cleanup actions.
2788 *
2789 * Note that we may have delayed dropping an mm in context_switch(). If
2790 * so, we finish that here outside of the runqueue lock. (Doing it
2791 * with the lock held can cause deadlocks; see schedule() for
2792 * details.)
2793 */
2794 static void finish_task_switch(struct rq *rq, struct task_struct *prev)
2795 __releases(rq->lock)
2796 {
2797 struct mm_struct *mm = rq->prev_mm;
2798 long prev_state;
2799 #ifdef CONFIG_SMP
2800 int post_schedule = 0;
2801
2802 if (current->sched_class->needs_post_schedule)
2803 post_schedule = current->sched_class->needs_post_schedule(rq);
2804 #endif
2805
2806 rq->prev_mm = NULL;
2807
2808 /*
2809 * A task struct has one reference for the use as "current".
2810 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2811 * schedule one last time. The schedule call will never return, and
2812 * the scheduled task must drop that reference.
2813 * The test for TASK_DEAD must occur while the runqueue locks are
2814 * still held, otherwise prev could be scheduled on another cpu, die
2815 * there before we look at prev->state, and then the reference would
2816 * be dropped twice.
2817 * Manfred Spraul <manfred@colorfullife.com>
2818 */
2819 prev_state = prev->state;
2820 finish_arch_switch(prev);
2821 perf_counter_task_sched_in(current, cpu_of(rq));
2822 finish_lock_switch(rq, prev);
2823 #ifdef CONFIG_SMP
2824 if (post_schedule)
2825 current->sched_class->post_schedule(rq);
2826 #endif
2827
2828 fire_sched_in_preempt_notifiers(current);
2829 if (mm)
2830 mmdrop(mm);
2831 if (unlikely(prev_state == TASK_DEAD)) {
2832 /*
2833 * Remove function-return probe instances associated with this
2834 * task and put them back on the free list.
2835 */
2836 kprobe_flush_task(prev);
2837 put_task_struct(prev);
2838 }
2839 }
2840
2841 /**
2842 * schedule_tail - first thing a freshly forked thread must call.
2843 * @prev: the thread we just switched away from.
2844 */
2845 asmlinkage void schedule_tail(struct task_struct *prev)
2846 __releases(rq->lock)
2847 {
2848 struct rq *rq = this_rq();
2849
2850 finish_task_switch(rq, prev);
2851 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2852 /* In this case, finish_task_switch does not reenable preemption */
2853 preempt_enable();
2854 #endif
2855 if (current->set_child_tid)
2856 put_user(task_pid_vnr(current), current->set_child_tid);
2857 }
2858
2859 /*
2860 * context_switch - switch to the new MM and the new
2861 * thread's register state.
2862 */
2863 static inline void
2864 context_switch(struct rq *rq, struct task_struct *prev,
2865 struct task_struct *next)
2866 {
2867 struct mm_struct *mm, *oldmm;
2868
2869 prepare_task_switch(rq, prev, next);
2870 trace_sched_switch(rq, prev, next);
2871 mm = next->mm;
2872 oldmm = prev->active_mm;
2873 /*
2874 * For paravirt, this is coupled with an exit in switch_to to
2875 * combine the page table reload and the switch backend into
2876 * one hypercall.
2877 */
2878 arch_start_context_switch(prev);
2879
2880 if (unlikely(!mm)) {
2881 next->active_mm = oldmm;
2882 atomic_inc(&oldmm->mm_count);
2883 enter_lazy_tlb(oldmm, next);
2884 } else
2885 switch_mm(oldmm, mm, next);
2886
2887 if (unlikely(!prev->mm)) {
2888 prev->active_mm = NULL;
2889 rq->prev_mm = oldmm;
2890 }
2891 /*
2892 * Since the runqueue lock will be released by the next
2893 * task (which is an invalid locking op but in the case
2894 * of the scheduler it's an obvious special-case), so we
2895 * do an early lockdep release here:
2896 */
2897 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2898 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2899 #endif
2900
2901 /* Here we just switch the register state and the stack. */
2902 switch_to(prev, next, prev);
2903
2904 barrier();
2905 /*
2906 * this_rq must be evaluated again because prev may have moved
2907 * CPUs since it called schedule(), thus the 'rq' on its stack
2908 * frame will be invalid.
2909 */
2910 finish_task_switch(this_rq(), prev);
2911 }
2912
2913 /*
2914 * nr_running, nr_uninterruptible and nr_context_switches:
2915 *
2916 * externally visible scheduler statistics: current number of runnable
2917 * threads, current number of uninterruptible-sleeping threads, total
2918 * number of context switches performed since bootup.
2919 */
2920 unsigned long nr_running(void)
2921 {
2922 unsigned long i, sum = 0;
2923
2924 for_each_online_cpu(i)
2925 sum += cpu_rq(i)->nr_running;
2926
2927 return sum;
2928 }
2929
2930 unsigned long nr_uninterruptible(void)
2931 {
2932 unsigned long i, sum = 0;
2933
2934 for_each_possible_cpu(i)
2935 sum += cpu_rq(i)->nr_uninterruptible;
2936
2937 /*
2938 * Since we read the counters lockless, it might be slightly
2939 * inaccurate. Do not allow it to go below zero though:
2940 */
2941 if (unlikely((long)sum < 0))
2942 sum = 0;
2943
2944 return sum;
2945 }
2946
2947 unsigned long long nr_context_switches(void)
2948 {
2949 int i;
2950 unsigned long long sum = 0;
2951
2952 for_each_possible_cpu(i)
2953 sum += cpu_rq(i)->nr_switches;
2954
2955 return sum;
2956 }
2957
2958 unsigned long nr_iowait(void)
2959 {
2960 unsigned long i, sum = 0;
2961
2962 for_each_possible_cpu(i)
2963 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2964
2965 return sum;
2966 }
2967
2968 /* Variables and functions for calc_load */
2969 static atomic_long_t calc_load_tasks;
2970 static unsigned long calc_load_update;
2971 unsigned long avenrun[3];
2972 EXPORT_SYMBOL(avenrun);
2973
2974 /**
2975 * get_avenrun - get the load average array
2976 * @loads: pointer to dest load array
2977 * @offset: offset to add
2978 * @shift: shift count to shift the result left
2979 *
2980 * These values are estimates at best, so no need for locking.
2981 */
2982 void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
2983 {
2984 loads[0] = (avenrun[0] + offset) << shift;
2985 loads[1] = (avenrun[1] + offset) << shift;
2986 loads[2] = (avenrun[2] + offset) << shift;
2987 }
2988
2989 static unsigned long
2990 calc_load(unsigned long load, unsigned long exp, unsigned long active)
2991 {
2992 load *= exp;
2993 load += active * (FIXED_1 - exp);
2994 return load >> FSHIFT;
2995 }
2996
2997 /*
2998 * calc_load - update the avenrun load estimates 10 ticks after the
2999 * CPUs have updated calc_load_tasks.
3000 */
3001 void calc_global_load(void)
3002 {
3003 unsigned long upd = calc_load_update + 10;
3004 long active;
3005
3006 if (time_before(jiffies, upd))
3007 return;
3008
3009 active = atomic_long_read(&calc_load_tasks);
3010 active = active > 0 ? active * FIXED_1 : 0;
3011
3012 avenrun[0] = calc_load(avenrun[0], EXP_1, active);
3013 avenrun[1] = calc_load(avenrun[1], EXP_5, active);
3014 avenrun[2] = calc_load(avenrun[2], EXP_15, active);
3015
3016 calc_load_update += LOAD_FREQ;
3017 }
3018
3019 /*
3020 * Either called from update_cpu_load() or from a cpu going idle
3021 */
3022 static void calc_load_account_active(struct rq *this_rq)
3023 {
3024 long nr_active, delta;
3025
3026 nr_active = this_rq->nr_running;
3027 nr_active += (long) this_rq->nr_uninterruptible;
3028
3029 if (nr_active != this_rq->calc_load_active) {
3030 delta = nr_active - this_rq->calc_load_active;
3031 this_rq->calc_load_active = nr_active;
3032 atomic_long_add(delta, &calc_load_tasks);
3033 }
3034 }
3035
3036 /*
3037 * Externally visible per-cpu scheduler statistics:
3038 * cpu_nr_migrations(cpu) - number of migrations into that cpu
3039 */
3040 u64 cpu_nr_migrations(int cpu)
3041 {
3042 return cpu_rq(cpu)->nr_migrations_in;
3043 }
3044
3045 /*
3046 * Update rq->cpu_load[] statistics. This function is usually called every
3047 * scheduler tick (TICK_NSEC).
3048 */
3049 static void update_cpu_load(struct rq *this_rq)
3050 {
3051 unsigned long this_load = this_rq->load.weight;
3052 int i, scale;
3053
3054 this_rq->nr_load_updates++;
3055
3056 /* Update our load: */
3057 for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
3058 unsigned long old_load, new_load;
3059
3060 /* scale is effectively 1 << i now, and >> i divides by scale */
3061
3062 old_load = this_rq->cpu_load[i];
3063 new_load = this_load;
3064 /*
3065 * Round up the averaging division if load is increasing. This
3066 * prevents us from getting stuck on 9 if the load is 10, for
3067 * example.
3068 */
3069 if (new_load > old_load)
3070 new_load += scale-1;
3071 this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
3072 }
3073
3074 if (time_after_eq(jiffies, this_rq->calc_load_update)) {
3075 this_rq->calc_load_update += LOAD_FREQ;
3076 calc_load_account_active(this_rq);
3077 }
3078 }
3079
3080 #ifdef CONFIG_SMP
3081
3082 /*
3083 * double_rq_lock - safely lock two runqueues
3084 *
3085 * Note this does not disable interrupts like task_rq_lock,
3086 * you need to do so manually before calling.
3087 */
3088 static void double_rq_lock(struct rq *rq1, struct rq *rq2)
3089 __acquires(rq1->lock)
3090 __acquires(rq2->lock)
3091 {
3092 BUG_ON(!irqs_disabled());
3093 if (rq1 == rq2) {
3094 spin_lock(&rq1->lock);
3095 __acquire(rq2->lock); /* Fake it out ;) */
3096 } else {
3097 if (rq1 < rq2) {
3098 spin_lock(&rq1->lock);
3099 spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
3100 } else {
3101 spin_lock(&rq2->lock);
3102 spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
3103 }
3104 }
3105 update_rq_clock(rq1);
3106 update_rq_clock(rq2);
3107 }
3108
3109 /*
3110 * double_rq_unlock - safely unlock two runqueues
3111 *
3112 * Note this does not restore interrupts like task_rq_unlock,
3113 * you need to do so manually after calling.
3114 */
3115 static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
3116 __releases(rq1->lock)
3117 __releases(rq2->lock)
3118 {
3119 spin_unlock(&rq1->lock);
3120 if (rq1 != rq2)
3121 spin_unlock(&rq2->lock);
3122 else
3123 __release(rq2->lock);
3124 }
3125
3126 /*
3127 * If dest_cpu is allowed for this process, migrate the task to it.
3128 * This is accomplished by forcing the cpu_allowed mask to only
3129 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
3130 * the cpu_allowed mask is restored.
3131 */
3132 static void sched_migrate_task(struct task_struct *p, int dest_cpu)
3133 {
3134 struct migration_req req;
3135 unsigned long flags;
3136 struct rq *rq;
3137
3138 rq = task_rq_lock(p, &flags);
3139 if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)
3140 || unlikely(!cpu_active(dest_cpu)))
3141 goto out;
3142
3143 /* force the process onto the specified CPU */
3144 if (migrate_task(p, dest_cpu, &req)) {
3145 /* Need to wait for migration thread (might exit: take ref). */
3146 struct task_struct *mt = rq->migration_thread;
3147
3148 get_task_struct(mt);
3149 task_rq_unlock(rq, &flags);
3150 wake_up_process(mt);
3151 put_task_struct(mt);
3152 wait_for_completion(&req.done);
3153
3154 return;
3155 }
3156 out:
3157 task_rq_unlock(rq, &flags);
3158 }
3159
3160 /*
3161 * sched_exec - execve() is a valuable balancing opportunity, because at
3162 * this point the task has the smallest effective memory and cache footprint.
3163 */
3164 void sched_exec(void)
3165 {
3166 int new_cpu, this_cpu = get_cpu();
3167 new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
3168 put_cpu();
3169 if (new_cpu != this_cpu)
3170 sched_migrate_task(current, new_cpu);
3171 }
3172
3173 /*
3174 * pull_task - move a task from a remote runqueue to the local runqueue.
3175 * Both runqueues must be locked.
3176 */
3177 static void pull_task(struct rq *src_rq, struct task_struct *p,
3178 struct rq *this_rq, int this_cpu)
3179 {
3180 deactivate_task(src_rq, p, 0);
3181 set_task_cpu(p, this_cpu);
3182 activate_task(this_rq, p, 0);
3183 /*
3184 * Note that idle threads have a prio of MAX_PRIO, for this test
3185 * to be always true for them.
3186 */
3187 check_preempt_curr(this_rq, p, 0);
3188 }
3189
3190 /*
3191 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
3192 */
3193 static
3194 int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
3195 struct sched_domain *sd, enum cpu_idle_type idle,
3196 int *all_pinned)
3197 {
3198 int tsk_cache_hot = 0;
3199 /*
3200 * We do not migrate tasks that are:
3201 * 1) running (obviously), or
3202 * 2) cannot be migrated to this CPU due to cpus_allowed, or
3203 * 3) are cache-hot on their current CPU.
3204 */
3205 if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) {
3206 schedstat_inc(p, se.nr_failed_migrations_affine);
3207 return 0;
3208 }
3209 *all_pinned = 0;
3210
3211 if (task_running(rq, p)) {
3212 schedstat_inc(p, se.nr_failed_migrations_running);
3213 return 0;
3214 }
3215
3216 /*
3217 * Aggressive migration if:
3218 * 1) task is cache cold, or
3219 * 2) too many balance attempts have failed.
3220 */
3221
3222 tsk_cache_hot = task_hot(p, rq->clock, sd);
3223 if (!tsk_cache_hot ||
3224 sd->nr_balance_failed > sd->cache_nice_tries) {
3225 #ifdef CONFIG_SCHEDSTATS
3226 if (tsk_cache_hot) {
3227 schedstat_inc(sd, lb_hot_gained[idle]);
3228 schedstat_inc(p, se.nr_forced_migrations);
3229 }
3230 #endif
3231 return 1;
3232 }
3233
3234 if (tsk_cache_hot) {
3235 schedstat_inc(p, se.nr_failed_migrations_hot);
3236 return 0;
3237 }
3238 return 1;
3239 }
3240
3241 static unsigned long
3242 balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
3243 unsigned long max_load_move, struct sched_domain *sd,
3244 enum cpu_idle_type idle, int *all_pinned,
3245 int *this_best_prio, struct rq_iterator *iterator)
3246 {
3247 int loops = 0, pulled = 0, pinned = 0;
3248 struct task_struct *p;
3249 long rem_load_move = max_load_move;
3250
3251 if (max_load_move == 0)
3252 goto out;
3253
3254 pinned = 1;
3255
3256 /*
3257 * Start the load-balancing iterator:
3258 */
3259 p = iterator->start(iterator->arg);
3260 next:
3261 if (!p || loops++ > sysctl_sched_nr_migrate)
3262 goto out;
3263
3264 if ((p->se.load.weight >> 1) > rem_load_move ||
3265 !can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
3266 p = iterator->next(iterator->arg);
3267 goto next;
3268 }
3269
3270 pull_task(busiest, p, this_rq, this_cpu);
3271 pulled++;
3272 rem_load_move -= p->se.load.weight;
3273
3274 #ifdef CONFIG_PREEMPT
3275 /*
3276 * NEWIDLE balancing is a source of latency, so preemptible kernels
3277 * will stop after the first task is pulled to minimize the critical
3278 * section.
3279 */
3280 if (idle == CPU_NEWLY_IDLE)
3281 goto out;
3282 #endif
3283
3284 /*
3285 * We only want to steal up to the prescribed amount of weighted load.
3286 */
3287 if (rem_load_move > 0) {
3288 if (p->prio < *this_best_prio)
3289 *this_best_prio = p->prio;
3290 p = iterator->next(iterator->arg);
3291 goto next;
3292 }
3293 out:
3294 /*
3295 * Right now, this is one of only two places pull_task() is called,
3296 * so we can safely collect pull_task() stats here rather than
3297 * inside pull_task().
3298 */
3299 schedstat_add(sd, lb_gained[idle], pulled);
3300
3301 if (all_pinned)
3302 *all_pinned = pinned;
3303
3304 return max_load_move - rem_load_move;
3305 }
3306
3307 /*
3308 * move_tasks tries to move up to max_load_move weighted load from busiest to
3309 * this_rq, as part of a balancing operation within domain "sd".
3310 * Returns 1 if successful and 0 otherwise.
3311 *
3312 * Called with both runqueues locked.
3313 */
3314 static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
3315 unsigned long max_load_move,
3316 struct sched_domain *sd, enum cpu_idle_type idle,
3317 int *all_pinned)
3318 {
3319 const struct sched_class *class = sched_class_highest;
3320 unsigned long total_load_moved = 0;
3321 int this_best_prio = this_rq->curr->prio;
3322
3323 do {
3324 total_load_moved +=
3325 class->load_balance(this_rq, this_cpu, busiest,
3326 max_load_move - total_load_moved,
3327 sd, idle, all_pinned, &this_best_prio);
3328 class = class->next;
3329
3330 #ifdef CONFIG_PREEMPT
3331 /*
3332 * NEWIDLE balancing is a source of latency, so preemptible
3333 * kernels will stop after the first task is pulled to minimize
3334 * the critical section.
3335 */
3336 if (idle == CPU_NEWLY_IDLE && this_rq->nr_running)
3337 break;
3338 #endif
3339 } while (class && max_load_move > total_load_moved);
3340
3341 return total_load_moved > 0;
3342 }
3343
3344 static int
3345 iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
3346 struct sched_domain *sd, enum cpu_idle_type idle,
3347 struct rq_iterator *iterator)
3348 {
3349 struct task_struct *p = iterator->start(iterator->arg);
3350 int pinned = 0;
3351
3352 while (p) {
3353 if (can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
3354 pull_task(busiest, p, this_rq, this_cpu);
3355 /*
3356 * Right now, this is only the second place pull_task()
3357 * is called, so we can safely collect pull_task()
3358 * stats here rather than inside pull_task().
3359 */
3360 schedstat_inc(sd, lb_gained[idle]);
3361
3362 return 1;
3363 }
3364 p = iterator->next(iterator->arg);
3365 }
3366
3367 return 0;
3368 }
3369
3370 /*
3371 * move_one_task tries to move exactly one task from busiest to this_rq, as
3372 * part of active balancing operations within "domain".
3373 * Returns 1 if successful and 0 otherwise.
3374 *
3375 * Called with both runqueues locked.
3376 */
3377 static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
3378 struct sched_domain *sd, enum cpu_idle_type idle)
3379 {
3380 const struct sched_class *class;
3381
3382 for (class = sched_class_highest; class; class = class->next)
3383 if (class->move_one_task(this_rq, this_cpu, busiest, sd, idle))
3384 return 1;
3385
3386 return 0;
3387 }
3388 /********** Helpers for find_busiest_group ************************/
3389 /*
3390 * sd_lb_stats - Structure to store the statistics of a sched_domain
3391 * during load balancing.
3392 */
3393 struct sd_lb_stats {
3394 struct sched_group *busiest; /* Busiest group in this sd */
3395 struct sched_group *this; /* Local group in this sd */
3396 unsigned long total_load; /* Total load of all groups in sd */
3397 unsigned long total_pwr; /* Total power of all groups in sd */
3398 unsigned long avg_load; /* Average load across all groups in sd */
3399
3400 /** Statistics of this group */
3401 unsigned long this_load;
3402 unsigned long this_load_per_task;
3403 unsigned long this_nr_running;
3404
3405 /* Statistics of the busiest group */
3406 unsigned long max_load;
3407 unsigned long busiest_load_per_task;
3408 unsigned long busiest_nr_running;
3409
3410 int group_imb; /* Is there imbalance in this sd */
3411 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
3412 int power_savings_balance; /* Is powersave balance needed for this sd */
3413 struct sched_group *group_min; /* Least loaded group in sd */
3414 struct sched_group *group_leader; /* Group which relieves group_min */
3415 unsigned long min_load_per_task; /* load_per_task in group_min */
3416 unsigned long leader_nr_running; /* Nr running of group_leader */
3417 unsigned long min_nr_running; /* Nr running of group_min */
3418 #endif
3419 };
3420
3421 /*
3422 * sg_lb_stats - stats of a sched_group required for load_balancing
3423 */
3424 struct sg_lb_stats {
3425 unsigned long avg_load; /*Avg load across the CPUs of the group */
3426 unsigned long group_load; /* Total load over the CPUs of the group */
3427 unsigned long sum_nr_running; /* Nr tasks running in the group */
3428 unsigned long sum_weighted_load; /* Weighted load of group's tasks */
3429 unsigned long group_capacity;
3430 int group_imb; /* Is there an imbalance in the group ? */
3431 };
3432
3433 /**
3434 * group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
3435 * @group: The group whose first cpu is to be returned.
3436 */
3437 static inline unsigned int group_first_cpu(struct sched_group *group)
3438 {
3439 return cpumask_first(sched_group_cpus(group));
3440 }
3441
3442 /**
3443 * get_sd_load_idx - Obtain the load index for a given sched domain.
3444 * @sd: The sched_domain whose load_idx is to be obtained.
3445 * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
3446 */
3447 static inline int get_sd_load_idx(struct sched_domain *sd,
3448 enum cpu_idle_type idle)
3449 {
3450 int load_idx;
3451
3452 switch (idle) {
3453 case CPU_NOT_IDLE:
3454 load_idx = sd->busy_idx;
3455 break;
3456
3457 case CPU_NEWLY_IDLE:
3458 load_idx = sd->newidle_idx;
3459 break;
3460 default:
3461 load_idx = sd->idle_idx;
3462 break;
3463 }
3464
3465 return load_idx;
3466 }
3467
3468
3469 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
3470 /**
3471 * init_sd_power_savings_stats - Initialize power savings statistics for
3472 * the given sched_domain, during load balancing.
3473 *
3474 * @sd: Sched domain whose power-savings statistics are to be initialized.
3475 * @sds: Variable containing the statistics for sd.
3476 * @idle: Idle status of the CPU at which we're performing load-balancing.
3477 */
3478 static inline void init_sd_power_savings_stats(struct sched_domain *sd,
3479 struct sd_lb_stats *sds, enum cpu_idle_type idle)
3480 {
3481 /*
3482 * Busy processors will not participate in power savings
3483 * balance.
3484 */
3485 if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
3486 sds->power_savings_balance = 0;
3487 else {
3488 sds->power_savings_balance = 1;
3489 sds->min_nr_running = ULONG_MAX;
3490 sds->leader_nr_running = 0;
3491 }
3492 }
3493
3494 /**
3495 * update_sd_power_savings_stats - Update the power saving stats for a
3496 * sched_domain while performing load balancing.
3497 *
3498 * @group: sched_group belonging to the sched_domain under consideration.
3499 * @sds: Variable containing the statistics of the sched_domain
3500 * @local_group: Does group contain the CPU for which we're performing
3501 * load balancing ?
3502 * @sgs: Variable containing the statistics of the group.
3503 */
3504 static inline void update_sd_power_savings_stats(struct sched_group *group,
3505 struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
3506 {
3507
3508 if (!sds->power_savings_balance)
3509 return;
3510
3511 /*
3512 * If the local group is idle or completely loaded
3513 * no need to do power savings balance at this domain
3514 */
3515 if (local_group && (sds->this_nr_running >= sgs->group_capacity ||
3516 !sds->this_nr_running))
3517 sds->power_savings_balance = 0;
3518
3519 /*
3520 * If a group is already running at full capacity or idle,
3521 * don't include that group in power savings calculations
3522 */
3523 if (!sds->power_savings_balance ||
3524 sgs->sum_nr_running >= sgs->group_capacity ||
3525 !sgs->sum_nr_running)
3526 return;
3527
3528 /*
3529 * Calculate the group which has the least non-idle load.
3530 * This is the group from where we need to pick up the load
3531 * for saving power
3532 */
3533 if ((sgs->sum_nr_running < sds->min_nr_running) ||
3534 (sgs->sum_nr_running == sds->min_nr_running &&
3535 group_first_cpu(group) > group_first_cpu(sds->group_min))) {
3536 sds->group_min = group;
3537 sds->min_nr_running = sgs->sum_nr_running;
3538 sds->min_load_per_task = sgs->sum_weighted_load /
3539 sgs->sum_nr_running;
3540 }
3541
3542 /*
3543 * Calculate the group which is almost near its
3544 * capacity but still has some space to pick up some load
3545 * from other group and save more power
3546 */
3547 if (sgs->sum_nr_running > sgs->group_capacity - 1)
3548 return;
3549
3550 if (sgs->sum_nr_running > sds->leader_nr_running ||
3551 (sgs->sum_nr_running == sds->leader_nr_running &&
3552 group_first_cpu(group) < group_first_cpu(sds->group_leader))) {
3553 sds->group_leader = group;
3554 sds->leader_nr_running = sgs->sum_nr_running;
3555 }
3556 }
3557
3558 /**
3559 * check_power_save_busiest_group - see if there is potential for some power-savings balance
3560 * @sds: Variable containing the statistics of the sched_domain
3561 * under consideration.
3562 * @this_cpu: Cpu at which we're currently performing load-balancing.
3563 * @imbalance: Variable to store the imbalance.
3564 *
3565 * Description:
3566 * Check if we have potential to perform some power-savings balance.
3567 * If yes, set the busiest group to be the least loaded group in the
3568 * sched_domain, so that it's CPUs can be put to idle.
3569 *
3570 * Returns 1 if there is potential to perform power-savings balance.
3571 * Else returns 0.
3572 */
3573 static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
3574 int this_cpu, unsigned long *imbalance)
3575 {
3576 if (!sds->power_savings_balance)
3577 return 0;
3578
3579 if (sds->this != sds->group_leader ||
3580 sds->group_leader == sds->group_min)
3581 return 0;
3582
3583 *imbalance = sds->min_load_per_task;
3584 sds->busiest = sds->group_min;
3585
3586 if (sched_mc_power_savings >= POWERSAVINGS_BALANCE_WAKEUP) {
3587 cpu_rq(this_cpu)->rd->sched_mc_preferred_wakeup_cpu =
3588 group_first_cpu(sds->group_leader);
3589 }
3590
3591 return 1;
3592
3593 }
3594 #else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
3595 static inline void init_sd_power_savings_stats(struct sched_domain *sd,
3596 struct sd_lb_stats *sds, enum cpu_idle_type idle)
3597 {
3598 return;
3599 }
3600
3601 static inline void update_sd_power_savings_stats(struct sched_group *group,
3602 struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
3603 {
3604 return;
3605 }
3606
3607 static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
3608 int this_cpu, unsigned long *imbalance)
3609 {
3610 return 0;
3611 }
3612 #endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
3613
3614
3615 /**
3616 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
3617 * @group: sched_group whose statistics are to be updated.
3618 * @this_cpu: Cpu for which load balance is currently performed.
3619 * @idle: Idle status of this_cpu
3620 * @load_idx: Load index of sched_domain of this_cpu for load calc.
3621 * @sd_idle: Idle status of the sched_domain containing group.
3622 * @local_group: Does group contain this_cpu.
3623 * @cpus: Set of cpus considered for load balancing.
3624 * @balance: Should we balance.
3625 * @sgs: variable to hold the statistics for this group.
3626 */
3627 static inline void update_sg_lb_stats(struct sched_group *group, int this_cpu,
3628 enum cpu_idle_type idle, int load_idx, int *sd_idle,
3629 int local_group, const struct cpumask *cpus,
3630 int *balance, struct sg_lb_stats *sgs)
3631 {
3632 unsigned long load, max_cpu_load, min_cpu_load;
3633 int i;
3634 unsigned int balance_cpu = -1, first_idle_cpu = 0;
3635 unsigned long sum_avg_load_per_task;
3636 unsigned long avg_load_per_task;
3637
3638 if (local_group)
3639 balance_cpu = group_first_cpu(group);
3640
3641 /* Tally up the load of all CPUs in the group */
3642 sum_avg_load_per_task = avg_load_per_task = 0;
3643 max_cpu_load = 0;
3644 min_cpu_load = ~0UL;
3645
3646 for_each_cpu_and(i, sched_group_cpus(group), cpus) {
3647 struct rq *rq = cpu_rq(i);
3648
3649 if (*sd_idle && rq->nr_running)
3650 *sd_idle = 0;
3651
3652 /* Bias balancing toward cpus of our domain */
3653 if (local_group) {
3654 if (idle_cpu(i) && !first_idle_cpu) {
3655 first_idle_cpu = 1;
3656 balance_cpu = i;
3657 }
3658
3659 load = target_load(i, load_idx);
3660 } else {
3661 load = source_load(i, load_idx);
3662 if (load > max_cpu_load)
3663 max_cpu_load = load;
3664 if (min_cpu_load > load)
3665 min_cpu_load = load;
3666 }
3667
3668 sgs->group_load += load;
3669 sgs->sum_nr_running += rq->nr_running;
3670 sgs->sum_weighted_load += weighted_cpuload(i);
3671
3672 sum_avg_load_per_task += cpu_avg_load_per_task(i);
3673 }
3674
3675 /*
3676 * First idle cpu or the first cpu(busiest) in this sched group
3677 * is eligible for doing load balancing at this and above
3678 * domains. In the newly idle case, we will allow all the cpu's
3679 * to do the newly idle load balance.
3680 */
3681 if (idle != CPU_NEWLY_IDLE && local_group &&
3682 balance_cpu != this_cpu && balance) {
3683 *balance = 0;
3684 return;
3685 }
3686
3687 /* Adjust by relative CPU power of the group */
3688 sgs->avg_load = sg_div_cpu_power(group,
3689 sgs->group_load * SCHED_LOAD_SCALE);
3690
3691
3692 /*
3693 * Consider the group unbalanced when the imbalance is larger
3694 * than the average weight of two tasks.
3695 *
3696 * APZ: with cgroup the avg task weight can vary wildly and
3697 * might not be a suitable number - should we keep a
3698 * normalized nr_running number somewhere that negates
3699 * the hierarchy?
3700 */
3701 avg_load_per_task = sg_div_cpu_power(group,
3702 sum_avg_load_per_task * SCHED_LOAD_SCALE);
3703
3704 if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task)
3705 sgs->group_imb = 1;
3706
3707 sgs->group_capacity = group->__cpu_power / SCHED_LOAD_SCALE;
3708
3709 }
3710
3711 /**
3712 * update_sd_lb_stats - Update sched_group's statistics for load balancing.
3713 * @sd: sched_domain whose statistics are to be updated.
3714 * @this_cpu: Cpu for which load balance is currently performed.
3715 * @idle: Idle status of this_cpu
3716 * @sd_idle: Idle status of the sched_domain containing group.
3717 * @cpus: Set of cpus considered for load balancing.
3718 * @balance: Should we balance.
3719 * @sds: variable to hold the statistics for this sched_domain.
3720 */
3721 static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
3722 enum cpu_idle_type idle, int *sd_idle,
3723 const struct cpumask *cpus, int *balance,
3724 struct sd_lb_stats *sds)
3725 {
3726 struct sched_group *group = sd->groups;
3727 struct sg_lb_stats sgs;
3728 int load_idx;
3729
3730 init_sd_power_savings_stats(sd, sds, idle);
3731 load_idx = get_sd_load_idx(sd, idle);
3732
3733 do {
3734 int local_group;
3735
3736 local_group = cpumask_test_cpu(this_cpu,
3737 sched_group_cpus(group));
3738 memset(&sgs, 0, sizeof(sgs));
3739 update_sg_lb_stats(group, this_cpu, idle, load_idx, sd_idle,
3740 local_group, cpus, balance, &sgs);
3741
3742 if (local_group && balance && !(*balance))
3743 return;
3744
3745 sds->total_load += sgs.group_load;
3746 sds->total_pwr += group->__cpu_power;
3747
3748 if (local_group) {
3749 sds->this_load = sgs.avg_load;
3750 sds->this = group;
3751 sds->this_nr_running = sgs.sum_nr_running;
3752 sds->this_load_per_task = sgs.sum_weighted_load;
3753 } else if (sgs.avg_load > sds->max_load &&
3754 (sgs.sum_nr_running > sgs.group_capacity ||
3755 sgs.group_imb)) {
3756 sds->max_load = sgs.avg_load;
3757 sds->busiest = group;
3758 sds->busiest_nr_running = sgs.sum_nr_running;
3759 sds->busiest_load_per_task = sgs.sum_weighted_load;
3760 sds->group_imb = sgs.group_imb;
3761 }
3762
3763 update_sd_power_savings_stats(group, sds, local_group, &sgs);
3764 group = group->next;
3765 } while (group != sd->groups);
3766
3767 }
3768
3769 /**
3770 * fix_small_imbalance - Calculate the minor imbalance that exists
3771 * amongst the groups of a sched_domain, during
3772 * load balancing.
3773 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
3774 * @this_cpu: The cpu at whose sched_domain we're performing load-balance.
3775 * @imbalance: Variable to store the imbalance.
3776 */
3777 static inline void fix_small_imbalance(struct sd_lb_stats *sds,
3778 int this_cpu, unsigned long *imbalance)
3779 {
3780 unsigned long tmp, pwr_now = 0, pwr_move = 0;
3781 unsigned int imbn = 2;
3782
3783 if (sds->this_nr_running) {
3784 sds->this_load_per_task /= sds->this_nr_running;
3785 if (sds->busiest_load_per_task >
3786 sds->this_load_per_task)
3787 imbn = 1;
3788 } else
3789 sds->this_load_per_task =
3790 cpu_avg_load_per_task(this_cpu);
3791
3792 if (sds->max_load - sds->this_load + sds->busiest_load_per_task >=
3793 sds->busiest_load_per_task * imbn) {
3794 *imbalance = sds->busiest_load_per_task;
3795 return;
3796 }
3797
3798 /*
3799 * OK, we don't have enough imbalance to justify moving tasks,
3800 * however we may be able to increase total CPU power used by
3801 * moving them.
3802 */
3803
3804 pwr_now += sds->busiest->__cpu_power *
3805 min(sds->busiest_load_per_task, sds->max_load);
3806 pwr_now += sds->this->__cpu_power *
3807 min(sds->this_load_per_task, sds->this_load);
3808 pwr_now /= SCHED_LOAD_SCALE;
3809
3810 /* Amount of load we'd subtract */
3811 tmp = sg_div_cpu_power(sds->busiest,
3812 sds->busiest_load_per_task * SCHED_LOAD_SCALE);
3813 if (sds->max_load > tmp)
3814 pwr_move += sds->busiest->__cpu_power *
3815 min(sds->busiest_load_per_task, sds->max_load - tmp);
3816
3817 /* Amount of load we'd add */
3818 if (sds->max_load * sds->busiest->__cpu_power <
3819 sds->busiest_load_per_task * SCHED_LOAD_SCALE)
3820 tmp = sg_div_cpu_power(sds->this,
3821 sds->max_load * sds->busiest->__cpu_power);
3822 else
3823 tmp = sg_div_cpu_power(sds->this,
3824 sds->busiest_load_per_task * SCHED_LOAD_SCALE);
3825 pwr_move += sds->this->__cpu_power *
3826 min(sds->this_load_per_task, sds->this_load + tmp);
3827 pwr_move /= SCHED_LOAD_SCALE;
3828
3829 /* Move if we gain throughput */
3830 if (pwr_move > pwr_now)
3831 *imbalance = sds->busiest_load_per_task;
3832 }
3833
3834 /**
3835 * calculate_imbalance - Calculate the amount of imbalance present within the
3836 * groups of a given sched_domain during load balance.
3837 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
3838 * @this_cpu: Cpu for which currently load balance is being performed.
3839 * @imbalance: The variable to store the imbalance.
3840 */
3841 static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
3842 unsigned long *imbalance)
3843 {
3844 unsigned long max_pull;
3845 /*
3846 * In the presence of smp nice balancing, certain scenarios can have
3847 * max load less than avg load(as we skip the groups at or below
3848 * its cpu_power, while calculating max_load..)
3849 */
3850 if (sds->max_load < sds->avg_load) {
3851 *imbalance = 0;
3852 return fix_small_imbalance(sds, this_cpu, imbalance);
3853 }
3854
3855 /* Don't want to pull so many tasks that a group would go idle */
3856 max_pull = min(sds->max_load - sds->avg_load,
3857 sds->max_load - sds->busiest_load_per_task);
3858
3859 /* How much load to actually move to equalise the imbalance */
3860 *imbalance = min(max_pull * sds->busiest->__cpu_power,
3861 (sds->avg_load - sds->this_load) * sds->this->__cpu_power)
3862 / SCHED_LOAD_SCALE;
3863
3864 /*
3865 * if *imbalance is less than the average load per runnable task
3866 * there is no gaurantee that any tasks will be moved so we'll have
3867 * a think about bumping its value to force at least one task to be
3868 * moved
3869 */
3870 if (*imbalance < sds->busiest_load_per_task)
3871 return fix_small_imbalance(sds, this_cpu, imbalance);
3872
3873 }
3874 /******* find_busiest_group() helpers end here *********************/
3875
3876 /**
3877 * find_busiest_group - Returns the busiest group within the sched_domain
3878 * if there is an imbalance. If there isn't an imbalance, and
3879 * the user has opted for power-savings, it returns a group whose
3880 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
3881 * such a group exists.
3882 *
3883 * Also calculates the amount of weighted load which should be moved
3884 * to restore balance.
3885 *
3886 * @sd: The sched_domain whose busiest group is to be returned.
3887 * @this_cpu: The cpu for which load balancing is currently being performed.
3888 * @imbalance: Variable which stores amount of weighted load which should
3889 * be moved to restore balance/put a group to idle.
3890 * @idle: The idle status of this_cpu.
3891 * @sd_idle: The idleness of sd
3892 * @cpus: The set of CPUs under consideration for load-balancing.
3893 * @balance: Pointer to a variable indicating if this_cpu
3894 * is the appropriate cpu to perform load balancing at this_level.
3895 *
3896 * Returns: - the busiest group if imbalance exists.
3897 * - If no imbalance and user has opted for power-savings balance,
3898 * return the least loaded group whose CPUs can be
3899 * put to idle by rebalancing its tasks onto our group.
3900 */
3901 static struct sched_group *
3902 find_busiest_group(struct sched_domain *sd, int this_cpu,
3903 unsigned long *imbalance, enum cpu_idle_type idle,
3904 int *sd_idle, const struct cpumask *cpus, int *balance)
3905 {
3906 struct sd_lb_stats sds;
3907
3908 memset(&sds, 0, sizeof(sds));
3909
3910 /*
3911 * Compute the various statistics relavent for load balancing at
3912 * this level.
3913 */
3914 update_sd_lb_stats(sd, this_cpu, idle, sd_idle, cpus,
3915 balance, &sds);
3916
3917 /* Cases where imbalance does not exist from POV of this_cpu */
3918 /* 1) this_cpu is not the appropriate cpu to perform load balancing
3919 * at this level.
3920 * 2) There is no busy sibling group to pull from.
3921 * 3) This group is the busiest group.
3922 * 4) This group is more busy than the avg busieness at this
3923 * sched_domain.
3924 * 5) The imbalance is within the specified limit.
3925 * 6) Any rebalance would lead to ping-pong
3926 */
3927 if (balance && !(*balance))
3928 goto ret;
3929
3930 if (!sds.busiest || sds.busiest_nr_running == 0)
3931 goto out_balanced;
3932
3933 if (sds.this_load >= sds.max_load)
3934 goto out_balanced;
3935
3936 sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;
3937
3938 if (sds.this_load >= sds.avg_load)
3939 goto out_balanced;
3940
3941 if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
3942 goto out_balanced;
3943
3944 sds.busiest_load_per_task /= sds.busiest_nr_running;
3945 if (sds.group_imb)
3946 sds.busiest_load_per_task =
3947 min(sds.busiest_load_per_task, sds.avg_load);
3948
3949 /*
3950 * We're trying to get all the cpus to the average_load, so we don't
3951 * want to push ourselves above the average load, nor do we wish to
3952 * reduce the max loaded cpu below the average load, as either of these
3953 * actions would just result in more rebalancing later, and ping-pong
3954 * tasks around. Thus we look for the minimum possible imbalance.
3955 * Negative imbalances (*we* are more loaded than anyone else) will
3956 * be counted as no imbalance for these purposes -- we can't fix that
3957 * by pulling tasks to us. Be careful of negative numbers as they'll
3958 * appear as very large values with unsigned longs.
3959 */
3960 if (sds.max_load <= sds.busiest_load_per_task)
3961 goto out_balanced;
3962
3963 /* Looks like there is an imbalance. Compute it */
3964 calculate_imbalance(&sds, this_cpu, imbalance);
3965 return sds.busiest;
3966
3967 out_balanced:
3968 /*
3969 * There is no obvious imbalance. But check if we can do some balancing
3970 * to save power.
3971 */
3972 if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
3973 return sds.busiest;
3974 ret:
3975 *imbalance = 0;
3976 return NULL;
3977 }
3978
3979 /*
3980 * find_busiest_queue - find the busiest runqueue among the cpus in group.
3981 */
3982 static struct rq *
3983 find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
3984 unsigned long imbalance, const struct cpumask *cpus)
3985 {
3986 struct rq *busiest = NULL, *rq;
3987 unsigned long max_load = 0;
3988 int i;
3989
3990 for_each_cpu(i, sched_group_cpus(group)) {
3991 unsigned long wl;
3992
3993 if (!cpumask_test_cpu(i, cpus))
3994 continue;
3995
3996 rq = cpu_rq(i);
3997 wl = weighted_cpuload(i);
3998
3999 if (rq->nr_running == 1 && wl > imbalance)
4000 continue;
4001
4002 if (wl > max_load) {
4003 max_load = wl;
4004 busiest = rq;
4005 }
4006 }
4007
4008 return busiest;
4009 }
4010
4011 /*
4012 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
4013 * so long as it is large enough.
4014 */
4015 #define MAX_PINNED_INTERVAL 512
4016
4017 /* Working cpumask for load_balance and load_balance_newidle. */
4018 static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
4019
4020 /*
4021 * Check this_cpu to ensure it is balanced within domain. Attempt to move
4022 * tasks if there is an imbalance.
4023 */
4024 static int load_balance(int this_cpu, struct rq *this_rq,
4025 struct sched_domain *sd, enum cpu_idle_type idle,
4026 int *balance)
4027 {
4028 int ld_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
4029 struct sched_group *group;
4030 unsigned long imbalance;
4031 struct rq *busiest;
4032 unsigned long flags;
4033 struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
4034
4035 cpumask_setall(cpus);
4036
4037 /*
4038 * When power savings policy is enabled for the parent domain, idle
4039 * sibling can pick up load irrespective of busy siblings. In this case,
4040 * let the state of idle sibling percolate up as CPU_IDLE, instead of
4041 * portraying it as CPU_NOT_IDLE.
4042 */
4043 if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
4044 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
4045 sd_idle = 1;
4046
4047 schedstat_inc(sd, lb_count[idle]);
4048
4049 redo:
4050 update_shares(sd);
4051 group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
4052 cpus, balance);
4053
4054 if (*balance == 0)
4055 goto out_balanced;
4056
4057 if (!group) {
4058 schedstat_inc(sd, lb_nobusyg[idle]);
4059 goto out_balanced;
4060 }
4061
4062 busiest = find_busiest_queue(group, idle, imbalance, cpus);
4063 if (!busiest) {
4064 schedstat_inc(sd, lb_nobusyq[idle]);
4065 goto out_balanced;
4066 }
4067
4068 BUG_ON(busiest == this_rq);
4069
4070 schedstat_add(sd, lb_imbalance[idle], imbalance);
4071
4072 ld_moved = 0;
4073 if (busiest->nr_running > 1) {
4074 /*
4075 * Attempt to move tasks. If find_busiest_group has found
4076 * an imbalance but busiest->nr_running <= 1, the group is
4077 * still unbalanced. ld_moved simply stays zero, so it is
4078 * correctly treated as an imbalance.
4079 */
4080 local_irq_save(flags);
4081 double_rq_lock(this_rq, busiest);
4082 ld_moved = move_tasks(this_rq, this_cpu, busiest,
4083 imbalance, sd, idle, &all_pinned);
4084 double_rq_unlock(this_rq, busiest);
4085 local_irq_restore(flags);
4086
4087 /*
4088 * some other cpu did the load balance for us.
4089 */
4090 if (ld_moved && this_cpu != smp_processor_id())
4091 resched_cpu(this_cpu);
4092
4093 /* All tasks on this runqueue were pinned by CPU affinity */
4094 if (unlikely(all_pinned)) {
4095 cpumask_clear_cpu(cpu_of(busiest), cpus);
4096 if (!cpumask_empty(cpus))
4097 goto redo;
4098 goto out_balanced;
4099 }
4100 }
4101
4102 if (!ld_moved) {
4103 schedstat_inc(sd, lb_failed[idle]);
4104 sd->nr_balance_failed++;
4105
4106 if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
4107
4108 spin_lock_irqsave(&busiest->lock, flags);
4109
4110 /* don't kick the migration_thread, if the curr
4111 * task on busiest cpu can't be moved to this_cpu
4112 */
4113 if (!cpumask_test_cpu(this_cpu,
4114 &busiest->curr->cpus_allowed)) {
4115 spin_unlock_irqrestore(&busiest->lock, flags);
4116 all_pinned = 1;
4117 goto out_one_pinned;
4118 }
4119
4120 if (!busiest->active_balance) {
4121 busiest->active_balance = 1;
4122 busiest->push_cpu = this_cpu;
4123 active_balance = 1;
4124 }
4125 spin_unlock_irqrestore(&busiest->lock, flags);
4126 if (active_balance)
4127 wake_up_process(busiest->migration_thread);
4128
4129 /*
4130 * We've kicked active balancing, reset the failure
4131 * counter.
4132 */
4133 sd->nr_balance_failed = sd->cache_nice_tries+1;
4134 }
4135 } else
4136 sd->nr_balance_failed = 0;
4137
4138 if (likely(!active_balance)) {
4139 /* We were unbalanced, so reset the balancing interval */
4140 sd->balance_interval = sd->min_interval;
4141 } else {
4142 /*
4143 * If we've begun active balancing, start to back off. This
4144 * case may not be covered by the all_pinned logic if there
4145 * is only 1 task on the busy runqueue (because we don't call
4146 * move_tasks).
4147 */
4148 if (sd->balance_interval < sd->max_interval)
4149 sd->balance_interval *= 2;
4150 }
4151
4152 if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
4153 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
4154 ld_moved = -1;
4155
4156 goto out;
4157
4158 out_balanced:
4159 schedstat_inc(sd, lb_balanced[idle]);
4160
4161 sd->nr_balance_failed = 0;
4162
4163 out_one_pinned:
4164 /* tune up the balancing interval */
4165 if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
4166 (sd->balance_interval < sd->max_interval))
4167 sd->balance_interval *= 2;
4168
4169 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
4170 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
4171 ld_moved = -1;
4172 else
4173 ld_moved = 0;
4174 out:
4175 if (ld_moved)
4176 update_shares(sd);
4177 return ld_moved;
4178 }
4179
4180 /*
4181 * Check this_cpu to ensure it is balanced within domain. Attempt to move
4182 * tasks if there is an imbalance.
4183 *
4184 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
4185 * this_rq is locked.
4186 */
4187 static int
4188 load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
4189 {
4190 struct sched_group *group;
4191 struct rq *busiest = NULL;
4192 unsigned long imbalance;
4193 int ld_moved = 0;
4194 int sd_idle = 0;
4195 int all_pinned = 0;
4196 struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
4197
4198 cpumask_setall(cpus);
4199
4200 /*
4201 * When power savings policy is enabled for the parent domain, idle
4202 * sibling can pick up load irrespective of busy siblings. In this case,
4203 * let the state of idle sibling percolate up as IDLE, instead of
4204 * portraying it as CPU_NOT_IDLE.
4205 */
4206 if (sd->flags & SD_SHARE_CPUPOWER &&
4207 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
4208 sd_idle = 1;
4209
4210 schedstat_inc(sd, lb_count[CPU_NEWLY_IDLE]);
4211 redo:
4212 update_shares_locked(this_rq, sd);
4213 group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE,
4214 &sd_idle, cpus, NULL);
4215 if (!group) {
4216 schedstat_inc(sd, lb_nobusyg[CPU_NEWLY_IDLE]);
4217 goto out_balanced;
4218 }
4219
4220 busiest = find_busiest_queue(group, CPU_NEWLY_IDLE, imbalance, cpus);
4221 if (!busiest) {
4222 schedstat_inc(sd, lb_nobusyq[CPU_NEWLY_IDLE]);
4223 goto out_balanced;
4224 }
4225
4226 BUG_ON(busiest == this_rq);
4227
4228 schedstat_add(sd, lb_imbalance[CPU_NEWLY_IDLE], imbalance);
4229
4230 ld_moved = 0;
4231 if (busiest->nr_running > 1) {
4232 /* Attempt to move tasks */
4233 double_lock_balance(this_rq, busiest);
4234 /* this_rq->clock is already updated */
4235 update_rq_clock(busiest);
4236 ld_moved = move_tasks(this_rq, this_cpu, busiest,
4237 imbalance, sd, CPU_NEWLY_IDLE,
4238 &all_pinned);
4239 double_unlock_balance(this_rq, busiest);
4240
4241 if (unlikely(all_pinned)) {
4242 cpumask_clear_cpu(cpu_of(busiest), cpus);
4243 if (!cpumask_empty(cpus))
4244 goto redo;
4245 }
4246 }
4247
4248 if (!ld_moved) {
4249 int active_balance = 0;
4250
4251 schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
4252 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
4253 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
4254 return -1;
4255
4256 if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
4257 return -1;
4258
4259 if (sd->nr_balance_failed++ < 2)
4260 return -1;
4261
4262 /*
4263 * The only task running in a non-idle cpu can be moved to this
4264 * cpu in an attempt to completely freeup the other CPU
4265 * package. The same method used to move task in load_balance()
4266 * have been extended for load_balance_newidle() to speedup
4267 * consolidation at sched_mc=POWERSAVINGS_BALANCE_WAKEUP (2)
4268 *
4269 * The package power saving logic comes from
4270 * find_busiest_group(). If there are no imbalance, then
4271 * f_b_g() will return NULL. However when sched_mc={1,2} then
4272 * f_b_g() will select a group from which a running task may be
4273 * pulled to this cpu in order to make the other package idle.
4274 * If there is no opportunity to make a package idle and if
4275 * there are no imbalance, then f_b_g() will return NULL and no
4276 * action will be taken in load_balance_newidle().
4277 *
4278 * Under normal task pull operation due to imbalance, there
4279 * will be more than one task in the source run queue and
4280 * move_tasks() will succeed. ld_moved will be true and this
4281 * active balance code will not be triggered.
4282 */
4283
4284 /* Lock busiest in correct order while this_rq is held */
4285 double_lock_balance(this_rq, busiest);
4286
4287 /*
4288 * don't kick the migration_thread, if the curr
4289 * task on busiest cpu can't be moved to this_cpu
4290 */
4291 if (!cpumask_test_cpu(this_cpu, &busiest->curr->cpus_allowed)) {
4292 double_unlock_balance(this_rq, busiest);
4293 all_pinned = 1;
4294 return ld_moved;
4295 }
4296
4297 if (!busiest->active_balance) {
4298 busiest->active_balance = 1;
4299 busiest->push_cpu = this_cpu;
4300 active_balance = 1;
4301 }
4302
4303 double_unlock_balance(this_rq, busiest);
4304 /*
4305 * Should not call ttwu while holding a rq->lock
4306 */
4307 spin_unlock(&this_rq->lock);
4308 if (active_balance)
4309 wake_up_process(busiest->migration_thread);
4310 spin_lock(&this_rq->lock);
4311
4312 } else
4313 sd->nr_balance_failed = 0;
4314
4315 update_shares_locked(this_rq, sd);
4316 return ld_moved;
4317
4318 out_balanced:
4319 schedstat_inc(sd, lb_balanced[CPU_NEWLY_IDLE]);
4320 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
4321 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
4322 return -1;
4323 sd->nr_balance_failed = 0;
4324
4325 return 0;
4326 }
4327
4328 /*
4329 * idle_balance is called by schedule() if this_cpu is about to become
4330 * idle. Attempts to pull tasks from other CPUs.
4331 */
4332 static void idle_balance(int this_cpu, struct rq *this_rq)
4333 {
4334 struct sched_domain *sd;
4335 int pulled_task = 0;
4336 unsigned long next_balance = jiffies + HZ;
4337
4338 for_each_domain(this_cpu, sd) {
4339 unsigned long interval;
4340
4341 if (!(sd->flags & SD_LOAD_BALANCE))
4342 continue;
4343
4344 if (sd->flags & SD_BALANCE_NEWIDLE)
4345 /* If we've pulled tasks over stop searching: */
4346 pulled_task = load_balance_newidle(this_cpu, this_rq,
4347 sd);
4348
4349 interval = msecs_to_jiffies(sd->balance_interval);
4350 if (time_after(next_balance, sd->last_balance + interval))
4351 next_balance = sd->last_balance + interval;
4352 if (pulled_task)
4353 break;
4354 }
4355 if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
4356 /*
4357 * We are going idle. next_balance may be set based on
4358 * a busy processor. So reset next_balance.
4359 */
4360 this_rq->next_balance = next_balance;
4361 }
4362 }
4363
4364 /*
4365 * active_load_balance is run by migration threads. It pushes running tasks
4366 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
4367 * running on each physical CPU where possible, and avoids physical /
4368 * logical imbalances.
4369 *
4370 * Called with busiest_rq locked.
4371 */
4372 static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
4373 {
4374 int target_cpu = busiest_rq->push_cpu;
4375 struct sched_domain *sd;
4376 struct rq *target_rq;
4377
4378 /* Is there any task to move? */
4379 if (busiest_rq->nr_running <= 1)
4380 return;
4381
4382 target_rq = cpu_rq(target_cpu);
4383
4384 /*
4385 * This condition is "impossible", if it occurs
4386 * we need to fix it. Originally reported by
4387 * Bjorn Helgaas on a 128-cpu setup.
4388 */
4389 BUG_ON(busiest_rq == target_rq);
4390
4391 /* move a task from busiest_rq to target_rq */
4392 double_lock_balance(busiest_rq, target_rq);
4393 update_rq_clock(busiest_rq);
4394 update_rq_clock(target_rq);
4395
4396 /* Search for an sd spanning us and the target CPU. */
4397 for_each_domain(target_cpu, sd) {
4398 if ((sd->flags & SD_LOAD_BALANCE) &&
4399 cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
4400 break;
4401 }
4402
4403 if (likely(sd)) {
4404 schedstat_inc(sd, alb_count);
4405
4406 if (move_one_task(target_rq, target_cpu, busiest_rq,
4407 sd, CPU_IDLE))
4408 schedstat_inc(sd, alb_pushed);
4409 else
4410 schedstat_inc(sd, alb_failed);
4411 }
4412 double_unlock_balance(busiest_rq, target_rq);
4413 }
4414
4415 #ifdef CONFIG_NO_HZ
4416 static struct {
4417 atomic_t load_balancer;
4418 cpumask_var_t cpu_mask;
4419 cpumask_var_t ilb_grp_nohz_mask;
4420 } nohz ____cacheline_aligned = {
4421 .load_balancer = ATOMIC_INIT(-1),
4422 };
4423
4424 int get_nohz_load_balancer(void)
4425 {
4426 return atomic_read(&nohz.load_balancer);
4427 }
4428
4429 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
4430 /**
4431 * lowest_flag_domain - Return lowest sched_domain containing flag.
4432 * @cpu: The cpu whose lowest level of sched domain is to
4433 * be returned.
4434 * @flag: The flag to check for the lowest sched_domain
4435 * for the given cpu.
4436 *
4437 * Returns the lowest sched_domain of a cpu which contains the given flag.
4438 */
4439 static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
4440 {
4441 struct sched_domain *sd;
4442
4443 for_each_domain(cpu, sd)
4444 if (sd && (sd->flags & flag))
4445 break;
4446
4447 return sd;
4448 }
4449
4450 /**
4451 * for_each_flag_domain - Iterates over sched_domains containing the flag.
4452 * @cpu: The cpu whose domains we're iterating over.
4453 * @sd: variable holding the value of the power_savings_sd
4454 * for cpu.
4455 * @flag: The flag to filter the sched_domains to be iterated.
4456 *
4457 * Iterates over all the scheduler domains for a given cpu that has the 'flag'
4458 * set, starting from the lowest sched_domain to the highest.
4459 */
4460 #define for_each_flag_domain(cpu, sd, flag) \
4461 for (sd = lowest_flag_domain(cpu, flag); \
4462 (sd && (sd->flags & flag)); sd = sd->parent)
4463
4464 /**
4465 * is_semi_idle_group - Checks if the given sched_group is semi-idle.
4466 * @ilb_group: group to be checked for semi-idleness
4467 *
4468 * Returns: 1 if the group is semi-idle. 0 otherwise.
4469 *
4470 * We define a sched_group to be semi idle if it has atleast one idle-CPU
4471 * and atleast one non-idle CPU. This helper function checks if the given
4472 * sched_group is semi-idle or not.
4473 */
4474 static inline int is_semi_idle_group(struct sched_group *ilb_group)
4475 {
4476 cpumask_and(nohz.ilb_grp_nohz_mask, nohz.cpu_mask,
4477 sched_group_cpus(ilb_group));
4478
4479 /*
4480 * A sched_group is semi-idle when it has atleast one busy cpu
4481 * and atleast one idle cpu.
4482 */
4483 if (cpumask_empty(nohz.ilb_grp_nohz_mask))
4484 return 0;
4485
4486 if (cpumask_equal(nohz.ilb_grp_nohz_mask, sched_group_cpus(ilb_group)))
4487 return 0;
4488
4489 return 1;
4490 }
4491 /**
4492 * find_new_ilb - Finds the optimum idle load balancer for nomination.
4493 * @cpu: The cpu which is nominating a new idle_load_balancer.
4494 *
4495 * Returns: Returns the id of the idle load balancer if it exists,
4496 * Else, returns >= nr_cpu_ids.
4497 *
4498 * This algorithm picks the idle load balancer such that it belongs to a
4499 * semi-idle powersavings sched_domain. The idea is to try and avoid
4500 * completely idle packages/cores just for the purpose of idle load balancing
4501 * when there are other idle cpu's which are better suited for that job.
4502 */
4503 static int find_new_ilb(int cpu)
4504 {
4505 struct sched_domain *sd;
4506 struct sched_group *ilb_group;
4507
4508 /*
4509 * Have idle load balancer selection from semi-idle packages only
4510 * when power-aware load balancing is enabled
4511 */
4512 if (!(sched_smt_power_savings || sched_mc_power_savings))
4513 goto out_done;
4514
4515 /*
4516 * Optimize for the case when we have no idle CPUs or only one
4517 * idle CPU. Don't walk the sched_domain hierarchy in such cases
4518 */
4519 if (cpumask_weight(nohz.cpu_mask) < 2)
4520 goto out_done;
4521
4522 for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) {
4523 ilb_group = sd->groups;
4524
4525 do {
4526 if (is_semi_idle_group(ilb_group))
4527 return cpumask_first(nohz.ilb_grp_nohz_mask);
4528
4529 ilb_group = ilb_group->next;
4530
4531 } while (ilb_group != sd->groups);
4532 }
4533
4534 out_done:
4535 return cpumask_first(nohz.cpu_mask);
4536 }
4537 #else /* (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */
4538 static inline int find_new_ilb(int call_cpu)
4539 {
4540 return cpumask_first(nohz.cpu_mask);
4541 }
4542 #endif
4543
4544 /*
4545 * This routine will try to nominate the ilb (idle load balancing)
4546 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
4547 * load balancing on behalf of all those cpus. If all the cpus in the system
4548 * go into this tickless mode, then there will be no ilb owner (as there is
4549 * no need for one) and all the cpus will sleep till the next wakeup event
4550 * arrives...
4551 *
4552 * For the ilb owner, tick is not stopped. And this tick will be used
4553 * for idle load balancing. ilb owner will still be part of
4554 * nohz.cpu_mask..
4555 *
4556 * While stopping the tick, this cpu will become the ilb owner if there
4557 * is no other owner. And will be the owner till that cpu becomes busy
4558 * or if all cpus in the system stop their ticks at which point
4559 * there is no need for ilb owner.
4560 *
4561 * When the ilb owner becomes busy, it nominates another owner, during the
4562 * next busy scheduler_tick()
4563 */
4564 int select_nohz_load_balancer(int stop_tick)
4565 {
4566 int cpu = smp_processor_id();
4567
4568 if (stop_tick) {
4569 cpu_rq(cpu)->in_nohz_recently = 1;
4570
4571 if (!cpu_active(cpu)) {
4572 if (atomic_read(&nohz.load_balancer) != cpu)
4573 return 0;
4574
4575 /*
4576 * If we are going offline and still the leader,
4577 * give up!
4578 */
4579 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
4580 BUG();
4581
4582 return 0;
4583 }
4584
4585 cpumask_set_cpu(cpu, nohz.cpu_mask);
4586
4587 /* time for ilb owner also to sleep */
4588 if (cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
4589 if (atomic_read(&nohz.load_balancer) == cpu)
4590 atomic_set(&nohz.load_balancer, -1);
4591 return 0;
4592 }
4593
4594 if (atomic_read(&nohz.load_balancer) == -1) {
4595 /* make me the ilb owner */
4596 if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
4597 return 1;
4598 } else if (atomic_read(&nohz.load_balancer) == cpu) {
4599 int new_ilb;
4600
4601 if (!(sched_smt_power_savings ||
4602 sched_mc_power_savings))
4603 return 1;
4604 /*
4605 * Check to see if there is a more power-efficient
4606 * ilb.
4607 */
4608 new_ilb = find_new_ilb(cpu);
4609 if (new_ilb < nr_cpu_ids && new_ilb != cpu) {
4610 atomic_set(&nohz.load_balancer, -1);
4611 resched_cpu(new_ilb);
4612 return 0;
4613 }
4614 return 1;
4615 }
4616 } else {
4617 if (!cpumask_test_cpu(cpu, nohz.cpu_mask))
4618 return 0;
4619
4620 cpumask_clear_cpu(cpu, nohz.cpu_mask);
4621
4622 if (atomic_read(&nohz.load_balancer) == cpu)
4623 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
4624 BUG();
4625 }
4626 return 0;
4627 }
4628 #endif
4629
4630 static DEFINE_SPINLOCK(balancing);
4631
4632 /*
4633 * It checks each scheduling domain to see if it is due to be balanced,
4634 * and initiates a balancing operation if so.
4635 *
4636 * Balancing parameters are set up in arch_init_sched_domains.
4637 */
4638 static void rebalance_domains(int cpu, enum cpu_idle_type idle)
4639 {
4640 int balance = 1;
4641 struct rq *rq = cpu_rq(cpu);
4642 unsigned long interval;
4643 struct sched_domain *sd;
4644 /* Earliest time when we have to do rebalance again */
4645 unsigned long next_balance = jiffies + 60*HZ;
4646 int update_next_balance = 0;
4647 int need_serialize;
4648
4649 for_each_domain(cpu, sd) {
4650 if (!(sd->flags & SD_LOAD_BALANCE))
4651 continue;
4652
4653 interval = sd->balance_interval;
4654 if (idle != CPU_IDLE)
4655 interval *= sd->busy_factor;
4656
4657 /* scale ms to jiffies */
4658 interval = msecs_to_jiffies(interval);
4659 if (unlikely(!interval))
4660 interval = 1;
4661 if (interval > HZ*NR_CPUS/10)
4662 interval = HZ*NR_CPUS/10;
4663
4664 need_serialize = sd->flags & SD_SERIALIZE;
4665
4666 if (need_serialize) {
4667 if (!spin_trylock(&balancing))
4668 goto out;
4669 }
4670
4671 if (time_after_eq(jiffies, sd->last_balance + interval)) {
4672 if (load_balance(cpu, rq, sd, idle, &balance)) {
4673 /*
4674 * We've pulled tasks over so either we're no
4675 * longer idle, or one of our SMT siblings is
4676 * not idle.
4677 */
4678 idle = CPU_NOT_IDLE;
4679 }
4680 sd->last_balance = jiffies;
4681 }
4682 if (need_serialize)
4683 spin_unlock(&balancing);
4684 out:
4685 if (time_after(next_balance, sd->last_balance + interval)) {
4686 next_balance = sd->last_balance + interval;
4687 update_next_balance = 1;
4688 }
4689
4690 /*
4691 * Stop the load balance at this level. There is another
4692 * CPU in our sched group which is doing load balancing more
4693 * actively.
4694 */
4695 if (!balance)
4696 break;
4697 }
4698
4699 /*
4700 * next_balance will be updated only when there is a need.
4701 * When the cpu is attached to null domain for ex, it will not be
4702 * updated.
4703 */
4704 if (likely(update_next_balance))
4705 rq->next_balance = next_balance;
4706 }
4707
4708 /*
4709 * run_rebalance_domains is triggered when needed from the scheduler tick.
4710 * In CONFIG_NO_HZ case, the idle load balance owner will do the
4711 * rebalancing for all the cpus for whom scheduler ticks are stopped.
4712 */
4713 static void run_rebalance_domains(struct softirq_action *h)
4714 {
4715 int this_cpu = smp_processor_id();
4716 struct rq *this_rq = cpu_rq(this_cpu);
4717 enum cpu_idle_type idle = this_rq->idle_at_tick ?
4718 CPU_IDLE : CPU_NOT_IDLE;
4719
4720 rebalance_domains(this_cpu, idle);
4721
4722 #ifdef CONFIG_NO_HZ
4723 /*
4724 * If this cpu is the owner for idle load balancing, then do the
4725 * balancing on behalf of the other idle cpus whose ticks are
4726 * stopped.
4727 */
4728 if (this_rq->idle_at_tick &&
4729 atomic_read(&nohz.load_balancer) == this_cpu) {
4730 struct rq *rq;
4731 int balance_cpu;
4732
4733 for_each_cpu(balance_cpu, nohz.cpu_mask) {
4734 if (balance_cpu == this_cpu)
4735 continue;
4736
4737 /*
4738 * If this cpu gets work to do, stop the load balancing
4739 * work being done for other cpus. Next load
4740 * balancing owner will pick it up.
4741 */
4742 if (need_resched())
4743 break;
4744
4745 rebalance_domains(balance_cpu, CPU_IDLE);
4746
4747 rq = cpu_rq(balance_cpu);
4748 if (time_after(this_rq->next_balance, rq->next_balance))
4749 this_rq->next_balance = rq->next_balance;
4750 }
4751 }
4752 #endif
4753 }
4754
4755 static inline int on_null_domain(int cpu)
4756 {
4757 return !rcu_dereference(cpu_rq(cpu)->sd);
4758 }
4759
4760 /*
4761 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
4762 *
4763 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
4764 * idle load balancing owner or decide to stop the periodic load balancing,
4765 * if the whole system is idle.
4766 */
4767 static inline void trigger_load_balance(struct rq *rq, int cpu)
4768 {
4769 #ifdef CONFIG_NO_HZ
4770 /*
4771 * If we were in the nohz mode recently and busy at the current
4772 * scheduler tick, then check if we need to nominate new idle
4773 * load balancer.
4774 */
4775 if (rq->in_nohz_recently && !rq->idle_at_tick) {
4776 rq->in_nohz_recently = 0;
4777
4778 if (atomic_read(&nohz.load_balancer) == cpu) {
4779 cpumask_clear_cpu(cpu, nohz.cpu_mask);
4780 atomic_set(&nohz.load_balancer, -1);
4781 }
4782
4783 if (atomic_read(&nohz.load_balancer) == -1) {
4784 int ilb = find_new_ilb(cpu);
4785
4786 if (ilb < nr_cpu_ids)
4787 resched_cpu(ilb);
4788 }
4789 }
4790
4791 /*
4792 * If this cpu is idle and doing idle load balancing for all the
4793 * cpus with ticks stopped, is it time for that to stop?
4794 */
4795 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
4796 cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
4797 resched_cpu(cpu);
4798 return;
4799 }
4800
4801 /*
4802 * If this cpu is idle and the idle load balancing is done by
4803 * someone else, then no need raise the SCHED_SOFTIRQ
4804 */
4805 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
4806 cpumask_test_cpu(cpu, nohz.cpu_mask))
4807 return;
4808 #endif
4809 /* Don't need to rebalance while attached to NULL domain */
4810 if (time_after_eq(jiffies, rq->next_balance) &&
4811 likely(!on_null_domain(cpu)))
4812 raise_softirq(SCHED_SOFTIRQ);
4813 }
4814
4815 #else /* CONFIG_SMP */
4816
4817 /*
4818 * on UP we do not need to balance between CPUs:
4819 */
4820 static inline void idle_balance(int cpu, struct rq *rq)
4821 {
4822 }
4823
4824 #endif
4825
4826 DEFINE_PER_CPU(struct kernel_stat, kstat);
4827
4828 EXPORT_PER_CPU_SYMBOL(kstat);
4829
4830 /*
4831 * Return any ns on the sched_clock that have not yet been accounted in
4832 * @p in case that task is currently running.
4833 *
4834 * Called with task_rq_lock() held on @rq.
4835 */
4836 static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
4837 {
4838 u64 ns = 0;
4839
4840 if (task_current(rq, p)) {
4841 update_rq_clock(rq);
4842 ns = rq->clock - p->se.exec_start;
4843 if ((s64)ns < 0)
4844 ns = 0;
4845 }
4846
4847 return ns;
4848 }
4849
4850 unsigned long long task_delta_exec(struct task_struct *p)
4851 {
4852 unsigned long flags;
4853 struct rq *rq;
4854 u64 ns = 0;
4855
4856 rq = task_rq_lock(p, &flags);
4857 ns = do_task_delta_exec(p, rq);
4858 task_rq_unlock(rq, &flags);
4859
4860 return ns;
4861 }
4862
4863 /*
4864 * Return accounted runtime for the task.
4865 * In case the task is currently running, return the runtime plus current's
4866 * pending runtime that have not been accounted yet.
4867 */
4868 unsigned long long task_sched_runtime(struct task_struct *p)
4869 {
4870 unsigned long flags;
4871 struct rq *rq;
4872 u64 ns = 0;
4873
4874 rq = task_rq_lock(p, &flags);
4875 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
4876 task_rq_unlock(rq, &flags);
4877
4878 return ns;
4879 }
4880
4881 /*
4882 * Return sum_exec_runtime for the thread group.
4883 * In case the task is currently running, return the sum plus current's
4884 * pending runtime that have not been accounted yet.
4885 *
4886 * Note that the thread group might have other running tasks as well,
4887 * so the return value not includes other pending runtime that other
4888 * running tasks might have.
4889 */
4890 unsigned long long thread_group_sched_runtime(struct task_struct *p)
4891 {
4892 struct task_cputime totals;
4893 unsigned long flags;
4894 struct rq *rq;
4895 u64 ns;
4896
4897 rq = task_rq_lock(p, &flags);
4898 thread_group_cputime(p, &totals);
4899 ns = totals.sum_exec_runtime + do_task_delta_exec(p, rq);
4900 task_rq_unlock(rq, &flags);
4901
4902 return ns;
4903 }
4904
4905 /*
4906 * Account user cpu time to a process.
4907 * @p: the process that the cpu time gets accounted to
4908 * @cputime: the cpu time spent in user space since the last update
4909 * @cputime_scaled: cputime scaled by cpu frequency
4910 */
4911 void account_user_time(struct task_struct *p, cputime_t cputime,
4912 cputime_t cputime_scaled)
4913 {
4914 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
4915 cputime64_t tmp;
4916
4917 /* Add user time to process. */
4918 p->utime = cputime_add(p->utime, cputime);
4919 p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
4920 account_group_user_time(p, cputime);
4921
4922 /* Add user time to cpustat. */
4923 tmp = cputime_to_cputime64(cputime);
4924 if (TASK_NICE(p) > 0)
4925 cpustat->nice = cputime64_add(cpustat->nice, tmp);
4926 else
4927 cpustat->user = cputime64_add(cpustat->user, tmp);
4928
4929 cpuacct_update_stats(p, CPUACCT_STAT_USER, cputime);
4930 /* Account for user time used */
4931 acct_update_integrals(p);
4932 }
4933
4934 /*
4935 * Account guest cpu time to a process.
4936 * @p: the process that the cpu time gets accounted to
4937 * @cputime: the cpu time spent in virtual machine since the last update
4938 * @cputime_scaled: cputime scaled by cpu frequency
4939 */
4940 static void account_guest_time(struct task_struct *p, cputime_t cputime,
4941 cputime_t cputime_scaled)
4942 {
4943 cputime64_t tmp;
4944 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
4945
4946 tmp = cputime_to_cputime64(cputime);
4947
4948 /* Add guest time to process. */
4949 p->utime = cputime_add(p->utime, cputime);
4950 p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
4951 account_group_user_time(p, cputime);
4952 p->gtime = cputime_add(p->gtime, cputime);
4953
4954 /* Add guest time to cpustat. */
4955 cpustat->user = cputime64_add(cpustat->user, tmp);
4956 cpustat->guest = cputime64_add(cpustat->guest, tmp);
4957 }
4958
4959 /*
4960 * Account system cpu time to a process.
4961 * @p: the process that the cpu time gets accounted to
4962 * @hardirq_offset: the offset to subtract from hardirq_count()
4963 * @cputime: the cpu time spent in kernel space since the last update
4964 * @cputime_scaled: cputime scaled by cpu frequency
4965 */
4966 void account_system_time(struct task_struct *p, int hardirq_offset,
4967 cputime_t cputime, cputime_t cputime_scaled)
4968 {
4969 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
4970 cputime64_t tmp;
4971
4972 if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
4973 account_guest_time(p, cputime, cputime_scaled);
4974 return;
4975 }
4976
4977 /* Add system time to process. */
4978 p->stime = cputime_add(p->stime, cputime);
4979 p->stimescaled = cputime_add(p->stimescaled, cputime_scaled);
4980 account_group_system_time(p, cputime);
4981
4982 /* Add system time to cpustat. */
4983 tmp = cputime_to_cputime64(cputime);
4984 if (hardirq_count() - hardirq_offset)
4985 cpustat->irq = cputime64_add(cpustat->irq, tmp);
4986 else if (softirq_count())
4987 cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
4988 else
4989 cpustat->system = cputime64_add(cpustat->system, tmp);
4990
4991 cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime);
4992
4993 /* Account for system time used */
4994 acct_update_integrals(p);
4995 }
4996
4997 /*
4998 * Account for involuntary wait time.
4999 * @steal: the cpu time spent in involuntary wait
5000 */
5001 void account_steal_time(cputime_t cputime)
5002 {
5003 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
5004 cputime64_t cputime64 = cputime_to_cputime64(cputime);
5005
5006 cpustat->steal = cputime64_add(cpustat->steal, cputime64);
5007 }
5008
5009 /*
5010 * Account for idle time.
5011 * @cputime: the cpu time spent in idle wait
5012 */
5013 void account_idle_time(cputime_t cputime)
5014 {
5015 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
5016 cputime64_t cputime64 = cputime_to_cputime64(cputime);
5017 struct rq *rq = this_rq();
5018
5019 if (atomic_read(&rq->nr_iowait) > 0)
5020 cpustat->iowait = cputime64_add(cpustat->iowait, cputime64);
5021 else
5022 cpustat->idle = cputime64_add(cpustat->idle, cputime64);
5023 }
5024
5025 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
5026
5027 /*
5028 * Account a single tick of cpu time.
5029 * @p: the process that the cpu time gets accounted to
5030 * @user_tick: indicates if the tick is a user or a system tick
5031 */
5032 void account_process_tick(struct task_struct *p, int user_tick)
5033 {
5034 cputime_t one_jiffy = jiffies_to_cputime(1);
5035 cputime_t one_jiffy_scaled = cputime_to_scaled(one_jiffy);
5036 struct rq *rq = this_rq();
5037
5038 if (user_tick)
5039 account_user_time(p, one_jiffy, one_jiffy_scaled);
5040 else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
5041 account_system_time(p, HARDIRQ_OFFSET, one_jiffy,
5042 one_jiffy_scaled);
5043 else
5044 account_idle_time(one_jiffy);
5045 }
5046
5047 /*
5048 * Account multiple ticks of steal time.
5049 * @p: the process from which the cpu time has been stolen
5050 * @ticks: number of stolen ticks
5051 */
5052 void account_steal_ticks(unsigned long ticks)
5053 {
5054 account_steal_time(jiffies_to_cputime(ticks));
5055 }
5056
5057 /*
5058 * Account multiple ticks of idle time.
5059 * @ticks: number of stolen ticks
5060 */
5061 void account_idle_ticks(unsigned long ticks)
5062 {
5063 account_idle_time(jiffies_to_cputime(ticks));
5064 }
5065
5066 #endif
5067
5068 /*
5069 * Use precise platform statistics if available:
5070 */
5071 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
5072 cputime_t task_utime(struct task_struct *p)
5073 {
5074 return p->utime;
5075 }
5076
5077 cputime_t task_stime(struct task_struct *p)
5078 {
5079 return p->stime;
5080 }
5081 #else
5082 cputime_t task_utime(struct task_struct *p)
5083 {
5084 clock_t utime = cputime_to_clock_t(p->utime),
5085 total = utime + cputime_to_clock_t(p->stime);
5086 u64 temp;
5087
5088 /*
5089 * Use CFS's precise accounting:
5090 */
5091 temp = (u64)nsec_to_clock_t(p->se.sum_exec_runtime);
5092
5093 if (total) {
5094 temp *= utime;
5095 do_div(temp, total);
5096 }
5097 utime = (clock_t)temp;
5098
5099 p->prev_utime = max(p->prev_utime, clock_t_to_cputime(utime));
5100 return p->prev_utime;
5101 }
5102
5103 cputime_t task_stime(struct task_struct *p)
5104 {
5105 clock_t stime;
5106
5107 /*
5108 * Use CFS's precise accounting. (we subtract utime from
5109 * the total, to make sure the total observed by userspace
5110 * grows monotonically - apps rely on that):
5111 */
5112 stime = nsec_to_clock_t(p->se.sum_exec_runtime) -
5113 cputime_to_clock_t(task_utime(p));
5114
5115 if (stime >= 0)
5116 p->prev_stime = max(p->prev_stime, clock_t_to_cputime(stime));
5117
5118 return p->prev_stime;
5119 }
5120 #endif
5121
5122 inline cputime_t task_gtime(struct task_struct *p)
5123 {
5124 return p->gtime;
5125 }
5126
5127 /*
5128 * This function gets called by the timer code, with HZ frequency.
5129 * We call it with interrupts disabled.
5130 *
5131 * It also gets called by the fork code, when changing the parent's
5132 * timeslices.
5133 */
5134 void scheduler_tick(void)
5135 {
5136 int cpu = smp_processor_id();
5137 struct rq *rq = cpu_rq(cpu);
5138 struct task_struct *curr = rq->curr;
5139
5140 sched_clock_tick();
5141
5142 spin_lock(&rq->lock);
5143 update_rq_clock(rq);
5144 update_cpu_load(rq);
5145 curr->sched_class->task_tick(rq, curr, 0);
5146 spin_unlock(&rq->lock);
5147
5148 perf_counter_task_tick(curr, cpu);
5149
5150 #ifdef CONFIG_SMP
5151 rq->idle_at_tick = idle_cpu(cpu);
5152 trigger_load_balance(rq, cpu);
5153 #endif
5154 }
5155
5156 notrace unsigned long get_parent_ip(unsigned long addr)
5157 {
5158 if (in_lock_functions(addr)) {
5159 addr = CALLER_ADDR2;
5160 if (in_lock_functions(addr))
5161 addr = CALLER_ADDR3;
5162 }
5163 return addr;
5164 }
5165
5166 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
5167 defined(CONFIG_PREEMPT_TRACER))
5168
5169 void __kprobes add_preempt_count(int val)
5170 {
5171 #ifdef CONFIG_DEBUG_PREEMPT
5172 /*
5173 * Underflow?
5174 */
5175 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
5176 return;
5177 #endif
5178 preempt_count() += val;
5179 #ifdef CONFIG_DEBUG_PREEMPT
5180 /*
5181 * Spinlock count overflowing soon?
5182 */
5183 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
5184 PREEMPT_MASK - 10);
5185 #endif
5186 if (preempt_count() == val)
5187 trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
5188 }
5189 EXPORT_SYMBOL(add_preempt_count);
5190
5191 void __kprobes sub_preempt_count(int val)
5192 {
5193 #ifdef CONFIG_DEBUG_PREEMPT
5194 /*
5195 * Underflow?
5196 */
5197 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
5198 return;
5199 /*
5200 * Is the spinlock portion underflowing?
5201 */
5202 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
5203 !(preempt_count() & PREEMPT_MASK)))
5204 return;
5205 #endif
5206
5207 if (preempt_count() == val)
5208 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
5209 preempt_count() -= val;
5210 }
5211 EXPORT_SYMBOL(sub_preempt_count);
5212
5213 #endif
5214
5215 /*
5216 * Print scheduling while atomic bug:
5217 */
5218 static noinline void __schedule_bug(struct task_struct *prev)
5219 {
5220 struct pt_regs *regs = get_irq_regs();
5221
5222 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
5223 prev->comm, prev->pid, preempt_count());
5224
5225 debug_show_held_locks(prev);
5226 print_modules();
5227 if (irqs_disabled())
5228 print_irqtrace_events(prev);
5229
5230 if (regs)
5231 show_regs(regs);
5232 else
5233 dump_stack();
5234 }
5235
5236 /*
5237 * Various schedule()-time debugging checks and statistics:
5238 */
5239 static inline void schedule_debug(struct task_struct *prev)
5240 {
5241 /*
5242 * Test if we are atomic. Since do_exit() needs to call into
5243 * schedule() atomically, we ignore that path for now.
5244 * Otherwise, whine if we are scheduling when we should not be.
5245 */
5246 if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
5247 __schedule_bug(prev);
5248
5249 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
5250
5251 schedstat_inc(this_rq(), sched_count);
5252 #ifdef CONFIG_SCHEDSTATS
5253 if (unlikely(prev->lock_depth >= 0)) {
5254 schedstat_inc(this_rq(), bkl_count);
5255 schedstat_inc(prev, sched_info.bkl_count);
5256 }
5257 #endif
5258 }
5259
5260 static void put_prev_task(struct rq *rq, struct task_struct *prev)
5261 {
5262 if (prev->state == TASK_RUNNING) {
5263 u64 runtime = prev->se.sum_exec_runtime;
5264
5265 runtime -= prev->se.prev_sum_exec_runtime;
5266 runtime = min_t(u64, runtime, 2*sysctl_sched_migration_cost);
5267
5268 /*
5269 * In order to avoid avg_overlap growing stale when we are
5270 * indeed overlapping and hence not getting put to sleep, grow
5271 * the avg_overlap on preemption.
5272 *
5273 * We use the average preemption runtime because that
5274 * correlates to the amount of cache footprint a task can
5275 * build up.
5276 */
5277 update_avg(&prev->se.avg_overlap, runtime);
5278 }
5279 prev->sched_class->put_prev_task(rq, prev);
5280 }
5281
5282 /*
5283 * Pick up the highest-prio task:
5284 */
5285 static inline struct task_struct *
5286 pick_next_task(struct rq *rq)
5287 {
5288 const struct sched_class *class;
5289 struct task_struct *p;
5290
5291 /*
5292 * Optimization: we know that if all tasks are in
5293 * the fair class we can call that function directly:
5294 */
5295 if (likely(rq->nr_running == rq->cfs.nr_running)) {
5296 p = fair_sched_class.pick_next_task(rq);
5297 if (likely(p))
5298 return p;
5299 }
5300
5301 class = sched_class_highest;
5302 for ( ; ; ) {
5303 p = class->pick_next_task(rq);
5304 if (p)
5305 return p;
5306 /*
5307 * Will never be NULL as the idle class always
5308 * returns a non-NULL p:
5309 */
5310 class = class->next;
5311 }
5312 }
5313
5314 /*
5315 * schedule() is the main scheduler function.
5316 */
5317 asmlinkage void __sched schedule(void)
5318 {
5319 struct task_struct *prev, *next;
5320 unsigned long *switch_count;
5321 struct rq *rq;
5322 int cpu;
5323
5324 need_resched:
5325 preempt_disable();
5326 cpu = smp_processor_id();
5327 rq = cpu_rq(cpu);
5328 rcu_qsctr_inc(cpu);
5329 prev = rq->curr;
5330 switch_count = &prev->nivcsw;
5331
5332 release_kernel_lock(prev);
5333 need_resched_nonpreemptible:
5334
5335 schedule_debug(prev);
5336
5337 if (sched_feat(HRTICK))
5338 hrtick_clear(rq);
5339
5340 spin_lock_irq(&rq->lock);
5341 update_rq_clock(rq);
5342 clear_tsk_need_resched(prev);
5343
5344 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
5345 if (unlikely(signal_pending_state(prev->state, prev)))
5346 prev->state = TASK_RUNNING;
5347 else
5348 deactivate_task(rq, prev, 1);
5349 switch_count = &prev->nvcsw;
5350 }
5351
5352 #ifdef CONFIG_SMP
5353 if (prev->sched_class->pre_schedule)
5354 prev->sched_class->pre_schedule(rq, prev);
5355 #endif
5356
5357 if (unlikely(!rq->nr_running))
5358 idle_balance(cpu, rq);
5359
5360 put_prev_task(rq, prev);
5361 next = pick_next_task(rq);
5362
5363 if (likely(prev != next)) {
5364 sched_info_switch(prev, next);
5365 perf_counter_task_sched_out(prev, next, cpu);
5366
5367 rq->nr_switches++;
5368 rq->curr = next;
5369 ++*switch_count;
5370
5371 context_switch(rq, prev, next); /* unlocks the rq */
5372 /*
5373 * the context switch might have flipped the stack from under
5374 * us, hence refresh the local variables.
5375 */
5376 cpu = smp_processor_id();
5377 rq = cpu_rq(cpu);
5378 } else
5379 spin_unlock_irq(&rq->lock);
5380
5381 if (unlikely(reacquire_kernel_lock(current) < 0))
5382 goto need_resched_nonpreemptible;
5383
5384 preempt_enable_no_resched();
5385 if (need_resched())
5386 goto need_resched;
5387 }
5388 EXPORT_SYMBOL(schedule);
5389
5390 #ifdef CONFIG_SMP
5391 /*
5392 * Look out! "owner" is an entirely speculative pointer
5393 * access and not reliable.
5394 */
5395 int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
5396 {
5397 unsigned int cpu;
5398 struct rq *rq;
5399
5400 if (!sched_feat(OWNER_SPIN))
5401 return 0;
5402
5403 #ifdef CONFIG_DEBUG_PAGEALLOC
5404 /*
5405 * Need to access the cpu field knowing that
5406 * DEBUG_PAGEALLOC could have unmapped it if
5407 * the mutex owner just released it and exited.
5408 */
5409 if (probe_kernel_address(&owner->cpu, cpu))
5410 goto out;
5411 #else
5412 cpu = owner->cpu;
5413 #endif
5414
5415 /*
5416 * Even if the access succeeded (likely case),
5417 * the cpu field may no longer be valid.
5418 */
5419 if (cpu >= nr_cpumask_bits)
5420 goto out;
5421
5422 /*
5423 * We need to validate that we can do a
5424 * get_cpu() and that we have the percpu area.
5425 */
5426 if (!cpu_online(cpu))
5427 goto out;
5428
5429 rq = cpu_rq(cpu);
5430
5431 for (;;) {
5432 /*
5433 * Owner changed, break to re-assess state.
5434 */
5435 if (lock->owner != owner)
5436 break;
5437
5438 /*
5439 * Is that owner really running on that cpu?
5440 */
5441 if (task_thread_info(rq->curr) != owner || need_resched())
5442 return 0;
5443
5444 cpu_relax();
5445 }
5446 out:
5447 return 1;
5448 }
5449 #endif
5450
5451 #ifdef CONFIG_PREEMPT
5452 /*
5453 * this is the entry point to schedule() from in-kernel preemption
5454 * off of preempt_enable. Kernel preemptions off return from interrupt
5455 * occur there and call schedule directly.
5456 */
5457 asmlinkage void __sched preempt_schedule(void)
5458 {
5459 struct thread_info *ti = current_thread_info();
5460
5461 /*
5462 * If there is a non-zero preempt_count or interrupts are disabled,
5463 * we do not want to preempt the current task. Just return..
5464 */
5465 if (likely(ti->preempt_count || irqs_disabled()))
5466 return;
5467
5468 do {
5469 add_preempt_count(PREEMPT_ACTIVE);
5470 schedule();
5471 sub_preempt_count(PREEMPT_ACTIVE);
5472
5473 /*
5474 * Check again in case we missed a preemption opportunity
5475 * between schedule and now.
5476 */
5477 barrier();
5478 } while (need_resched());
5479 }
5480 EXPORT_SYMBOL(preempt_schedule);
5481
5482 /*
5483 * this is the entry point to schedule() from kernel preemption
5484 * off of irq context.
5485 * Note, that this is called and return with irqs disabled. This will
5486 * protect us against recursive calling from irq.
5487 */
5488 asmlinkage void __sched preempt_schedule_irq(void)
5489 {
5490 struct thread_info *ti = current_thread_info();
5491
5492 /* Catch callers which need to be fixed */
5493 BUG_ON(ti->preempt_count || !irqs_disabled());
5494
5495 do {
5496 add_preempt_count(PREEMPT_ACTIVE);
5497 local_irq_enable();
5498 schedule();
5499 local_irq_disable();
5500 sub_preempt_count(PREEMPT_ACTIVE);
5501
5502 /*
5503 * Check again in case we missed a preemption opportunity
5504 * between schedule and now.
5505 */
5506 barrier();
5507 } while (need_resched());
5508 }
5509
5510 #endif /* CONFIG_PREEMPT */
5511
5512 int default_wake_function(wait_queue_t *curr, unsigned mode, int sync,
5513 void *key)
5514 {
5515 return try_to_wake_up(curr->private, mode, sync);
5516 }
5517 EXPORT_SYMBOL(default_wake_function);
5518
5519 /*
5520 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
5521 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
5522 * number) then we wake all the non-exclusive tasks and one exclusive task.
5523 *
5524 * There are circumstances in which we can try to wake a task which has already
5525 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
5526 * zero in this (rare) case, and we handle it by continuing to scan the queue.
5527 */
5528 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
5529 int nr_exclusive, int sync, void *key)
5530 {
5531 wait_queue_t *curr, *next;
5532
5533 list_for_each_entry_safe(curr, next, &q->task_list, task_list) {
5534 unsigned flags = curr->flags;
5535
5536 if (curr->func(curr, mode, sync, key) &&
5537 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
5538 break;
5539 }
5540 }
5541
5542 /**
5543 * __wake_up - wake up threads blocked on a waitqueue.
5544 * @q: the waitqueue
5545 * @mode: which threads
5546 * @nr_exclusive: how many wake-one or wake-many threads to wake up
5547 * @key: is directly passed to the wakeup function
5548 *
5549 * It may be assumed that this function implies a write memory barrier before
5550 * changing the task state if and only if any tasks are woken up.
5551 */
5552 void __wake_up(wait_queue_head_t *q, unsigned int mode,
5553 int nr_exclusive, void *key)
5554 {
5555 unsigned long flags;
5556
5557 spin_lock_irqsave(&q->lock, flags);
5558 __wake_up_common(q, mode, nr_exclusive, 0, key);
5559 spin_unlock_irqrestore(&q->lock, flags);
5560 }
5561 EXPORT_SYMBOL(__wake_up);
5562
5563 /*
5564 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
5565 */
5566 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
5567 {
5568 __wake_up_common(q, mode, 1, 0, NULL);
5569 }
5570
5571 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key)
5572 {
5573 __wake_up_common(q, mode, 1, 0, key);
5574 }
5575
5576 /**
5577 * __wake_up_sync_key - wake up threads blocked on a waitqueue.
5578 * @q: the waitqueue
5579 * @mode: which threads
5580 * @nr_exclusive: how many wake-one or wake-many threads to wake up
5581 * @key: opaque value to be passed to wakeup targets
5582 *
5583 * The sync wakeup differs that the waker knows that it will schedule
5584 * away soon, so while the target thread will be woken up, it will not
5585 * be migrated to another CPU - ie. the two threads are 'synchronized'
5586 * with each other. This can prevent needless bouncing between CPUs.
5587 *
5588 * On UP it can prevent extra preemption.
5589 *
5590 * It may be assumed that this function implies a write memory barrier before
5591 * changing the task state if and only if any tasks are woken up.
5592 */
5593 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
5594 int nr_exclusive, void *key)
5595 {
5596 unsigned long flags;
5597 int sync = 1;
5598
5599 if (unlikely(!q))
5600 return;
5601
5602 if (unlikely(!nr_exclusive))
5603 sync = 0;
5604
5605 spin_lock_irqsave(&q->lock, flags);
5606 __wake_up_common(q, mode, nr_exclusive, sync, key);
5607 spin_unlock_irqrestore(&q->lock, flags);
5608 }
5609 EXPORT_SYMBOL_GPL(__wake_up_sync_key);
5610
5611 /*
5612 * __wake_up_sync - see __wake_up_sync_key()
5613 */
5614 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
5615 {
5616 __wake_up_sync_key(q, mode, nr_exclusive, NULL);
5617 }
5618 EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
5619
5620 /**
5621 * complete: - signals a single thread waiting on this completion
5622 * @x: holds the state of this particular completion
5623 *
5624 * This will wake up a single thread waiting on this completion. Threads will be
5625 * awakened in the same order in which they were queued.
5626 *
5627 * See also complete_all(), wait_for_completion() and related routines.
5628 *
5629 * It may be assumed that this function implies a write memory barrier before
5630 * changing the task state if and only if any tasks are woken up.
5631 */
5632 void complete(struct completion *x)
5633 {
5634 unsigned long flags;
5635
5636 spin_lock_irqsave(&x->wait.lock, flags);
5637 x->done++;
5638 __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL);
5639 spin_unlock_irqrestore(&x->wait.lock, flags);
5640 }
5641 EXPORT_SYMBOL(complete);
5642
5643 /**
5644 * complete_all: - signals all threads waiting on this completion
5645 * @x: holds the state of this particular completion
5646 *
5647 * This will wake up all threads waiting on this particular completion event.
5648 *
5649 * It may be assumed that this function implies a write memory barrier before
5650 * changing the task state if and only if any tasks are woken up.
5651 */
5652 void complete_all(struct completion *x)
5653 {
5654 unsigned long flags;
5655
5656 spin_lock_irqsave(&x->wait.lock, flags);
5657 x->done += UINT_MAX/2;
5658 __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL);
5659 spin_unlock_irqrestore(&x->wait.lock, flags);
5660 }
5661 EXPORT_SYMBOL(complete_all);
5662
5663 static inline long __sched
5664 do_wait_for_common(struct completion *x, long timeout, int state)
5665 {
5666 if (!x->done) {
5667 DECLARE_WAITQUEUE(wait, current);
5668
5669 wait.flags |= WQ_FLAG_EXCLUSIVE;
5670 __add_wait_queue_tail(&x->wait, &wait);
5671 do {
5672 if (signal_pending_state(state, current)) {
5673 timeout = -ERESTARTSYS;
5674 break;
5675 }
5676 __set_current_state(state);
5677 spin_unlock_irq(&x->wait.lock);
5678 timeout = schedule_timeout(timeout);
5679 spin_lock_irq(&x->wait.lock);
5680 } while (!x->done && timeout);
5681 __remove_wait_queue(&x->wait, &wait);
5682 if (!x->done)
5683 return timeout;
5684 }
5685 x->done--;
5686 return timeout ?: 1;
5687 }
5688
5689 static long __sched
5690 wait_for_common(struct completion *x, long timeout, int state)
5691 {
5692 might_sleep();
5693
5694 spin_lock_irq(&x->wait.lock);
5695 timeout = do_wait_for_common(x, timeout, state);
5696 spin_unlock_irq(&x->wait.lock);
5697 return timeout;
5698 }
5699
5700 /**
5701 * wait_for_completion: - waits for completion of a task
5702 * @x: holds the state of this particular completion
5703 *
5704 * This waits to be signaled for completion of a specific task. It is NOT
5705 * interruptible and there is no timeout.
5706 *
5707 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
5708 * and interrupt capability. Also see complete().
5709 */
5710 void __sched wait_for_completion(struct completion *x)
5711 {
5712 wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
5713 }
5714 EXPORT_SYMBOL(wait_for_completion);
5715
5716 /**
5717 * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
5718 * @x: holds the state of this particular completion
5719 * @timeout: timeout value in jiffies
5720 *
5721 * This waits for either a completion of a specific task to be signaled or for a
5722 * specified timeout to expire. The timeout is in jiffies. It is not
5723 * interruptible.
5724 */
5725 unsigned long __sched
5726 wait_for_completion_timeout(struct completion *x, unsigned long timeout)
5727 {
5728 return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE);
5729 }
5730 EXPORT_SYMBOL(wait_for_completion_timeout);
5731
5732 /**
5733 * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
5734 * @x: holds the state of this particular completion
5735 *
5736 * This waits for completion of a specific task to be signaled. It is
5737 * interruptible.
5738 */
5739 int __sched wait_for_completion_interruptible(struct completion *x)
5740 {
5741 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
5742 if (t == -ERESTARTSYS)
5743 return t;
5744 return 0;
5745 }
5746 EXPORT_SYMBOL(wait_for_completion_interruptible);
5747
5748 /**
5749 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
5750 * @x: holds the state of this particular completion
5751 * @timeout: timeout value in jiffies
5752 *
5753 * This waits for either a completion of a specific task to be signaled or for a
5754 * specified timeout to expire. It is interruptible. The timeout is in jiffies.
5755 */
5756 unsigned long __sched
5757 wait_for_completion_interruptible_timeout(struct completion *x,
5758 unsigned long timeout)
5759 {
5760 return wait_for_common(x, timeout, TASK_INTERRUPTIBLE);
5761 }
5762 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
5763
5764 /**
5765 * wait_for_completion_killable: - waits for completion of a task (killable)
5766 * @x: holds the state of this particular completion
5767 *
5768 * This waits to be signaled for completion of a specific task. It can be
5769 * interrupted by a kill signal.
5770 */
5771 int __sched wait_for_completion_killable(struct completion *x)
5772 {
5773 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE);
5774 if (t == -ERESTARTSYS)
5775 return t;
5776 return 0;
5777 }
5778 EXPORT_SYMBOL(wait_for_completion_killable);
5779
5780 /**
5781 * try_wait_for_completion - try to decrement a completion without blocking
5782 * @x: completion structure
5783 *
5784 * Returns: 0 if a decrement cannot be done without blocking
5785 * 1 if a decrement succeeded.
5786 *
5787 * If a completion is being used as a counting completion,
5788 * attempt to decrement the counter without blocking. This
5789 * enables us to avoid waiting if the resource the completion
5790 * is protecting is not available.
5791 */
5792 bool try_wait_for_completion(struct completion *x)
5793 {
5794 int ret = 1;
5795
5796 spin_lock_irq(&x->wait.lock);
5797 if (!x->done)
5798 ret = 0;
5799 else
5800 x->done--;
5801 spin_unlock_irq(&x->wait.lock);
5802 return ret;
5803 }
5804 EXPORT_SYMBOL(try_wait_for_completion);
5805
5806 /**
5807 * completion_done - Test to see if a completion has any waiters
5808 * @x: completion structure
5809 *
5810 * Returns: 0 if there are waiters (wait_for_completion() in progress)
5811 * 1 if there are no waiters.
5812 *
5813 */
5814 bool completion_done(struct completion *x)
5815 {
5816 int ret = 1;
5817
5818 spin_lock_irq(&x->wait.lock);
5819 if (!x->done)
5820 ret = 0;
5821 spin_unlock_irq(&x->wait.lock);
5822 return ret;
5823 }
5824 EXPORT_SYMBOL(completion_done);
5825
5826 static long __sched
5827 sleep_on_common(wait_queue_head_t *q, int state, long timeout)
5828 {
5829 unsigned long flags;
5830 wait_queue_t wait;
5831
5832 init_waitqueue_entry(&wait, current);
5833
5834 __set_current_state(state);
5835
5836 spin_lock_irqsave(&q->lock, flags);
5837 __add_wait_queue(q, &wait);
5838 spin_unlock(&q->lock);
5839 timeout = schedule_timeout(timeout);
5840 spin_lock_irq(&q->lock);
5841 __remove_wait_queue(q, &wait);
5842 spin_unlock_irqrestore(&q->lock, flags);
5843
5844 return timeout;
5845 }
5846
5847 void __sched interruptible_sleep_on(wait_queue_head_t *q)
5848 {
5849 sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
5850 }
5851 EXPORT_SYMBOL(interruptible_sleep_on);
5852
5853 long __sched
5854 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
5855 {
5856 return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
5857 }
5858 EXPORT_SYMBOL(interruptible_sleep_on_timeout);
5859
5860 void __sched sleep_on(wait_queue_head_t *q)
5861 {
5862 sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
5863 }
5864 EXPORT_SYMBOL(sleep_on);
5865
5866 long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
5867 {
5868 return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
5869 }
5870 EXPORT_SYMBOL(sleep_on_timeout);
5871
5872 #ifdef CONFIG_RT_MUTEXES
5873
5874 /*
5875 * rt_mutex_setprio - set the current priority of a task
5876 * @p: task
5877 * @prio: prio value (kernel-internal form)
5878 *
5879 * This function changes the 'effective' priority of a task. It does
5880 * not touch ->normal_prio like __setscheduler().
5881 *
5882 * Used by the rt_mutex code to implement priority inheritance logic.
5883 */
5884 void rt_mutex_setprio(struct task_struct *p, int prio)
5885 {
5886 unsigned long flags;
5887 int oldprio, on_rq, running;
5888 struct rq *rq;
5889 const struct sched_class *prev_class = p->sched_class;
5890
5891 BUG_ON(prio < 0 || prio > MAX_PRIO);
5892
5893 rq = task_rq_lock(p, &flags);
5894 update_rq_clock(rq);
5895
5896 oldprio = p->prio;
5897 on_rq = p->se.on_rq;
5898 running = task_current(rq, p);
5899 if (on_rq)
5900 dequeue_task(rq, p, 0);
5901 if (running)
5902 p->sched_class->put_prev_task(rq, p);
5903
5904 if (rt_prio(prio))
5905 p->sched_class = &rt_sched_class;
5906 else
5907 p->sched_class = &fair_sched_class;
5908
5909 p->prio = prio;
5910
5911 if (running)
5912 p->sched_class->set_curr_task(rq);
5913 if (on_rq) {
5914 enqueue_task(rq, p, 0);
5915
5916 check_class_changed(rq, p, prev_class, oldprio, running);
5917 }
5918 task_rq_unlock(rq, &flags);
5919 }
5920
5921 #endif
5922
5923 void set_user_nice(struct task_struct *p, long nice)
5924 {
5925 int old_prio, delta, on_rq;
5926 unsigned long flags;
5927 struct rq *rq;
5928
5929 if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
5930 return;
5931 /*
5932 * We have to be careful, if called from sys_setpriority(),
5933 * the task might be in the middle of scheduling on another CPU.
5934 */
5935 rq = task_rq_lock(p, &flags);
5936 update_rq_clock(rq);
5937 /*
5938 * The RT priorities are set via sched_setscheduler(), but we still
5939 * allow the 'normal' nice value to be set - but as expected
5940 * it wont have any effect on scheduling until the task is
5941 * SCHED_FIFO/SCHED_RR:
5942 */
5943 if (task_has_rt_policy(p)) {
5944 p->static_prio = NICE_TO_PRIO(nice);
5945 goto out_unlock;
5946 }
5947 on_rq = p->se.on_rq;
5948 if (on_rq)
5949 dequeue_task(rq, p, 0);
5950
5951 p->static_prio = NICE_TO_PRIO(nice);
5952 set_load_weight(p);
5953 old_prio = p->prio;
5954 p->prio = effective_prio(p);
5955 delta = p->prio - old_prio;
5956
5957 if (on_rq) {
5958 enqueue_task(rq, p, 0);
5959 /*
5960 * If the task increased its priority or is running and
5961 * lowered its priority, then reschedule its CPU:
5962 */
5963 if (delta < 0 || (delta > 0 && task_running(rq, p)))
5964 resched_task(rq->curr);
5965 }
5966 out_unlock:
5967 task_rq_unlock(rq, &flags);
5968 }
5969 EXPORT_SYMBOL(set_user_nice);
5970
5971 /*
5972 * can_nice - check if a task can reduce its nice value
5973 * @p: task
5974 * @nice: nice value
5975 */
5976 int can_nice(const struct task_struct *p, const int nice)
5977 {
5978 /* convert nice value [19,-20] to rlimit style value [1,40] */
5979 int nice_rlim = 20 - nice;
5980
5981 return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
5982 capable(CAP_SYS_NICE));
5983 }
5984
5985 #ifdef __ARCH_WANT_SYS_NICE
5986
5987 /*
5988 * sys_nice - change the priority of the current process.
5989 * @increment: priority increment
5990 *
5991 * sys_setpriority is a more generic, but much slower function that
5992 * does similar things.
5993 */
5994 SYSCALL_DEFINE1(nice, int, increment)
5995 {
5996 long nice, retval;
5997
5998 /*
5999 * Setpriority might change our priority at the same moment.
6000 * We don't have to worry. Conceptually one call occurs first
6001 * and we have a single winner.
6002 */
6003 if (increment < -40)
6004 increment = -40;
6005 if (increment > 40)
6006 increment = 40;
6007
6008 nice = TASK_NICE(current) + increment;
6009 if (nice < -20)
6010 nice = -20;
6011 if (nice > 19)
6012 nice = 19;
6013
6014 if (increment < 0 && !can_nice(current, nice))
6015 return -EPERM;
6016
6017 retval = security_task_setnice(current, nice);
6018 if (retval)
6019 return retval;
6020
6021 set_user_nice(current, nice);
6022 return 0;
6023 }
6024
6025 #endif
6026
6027 /**
6028 * task_prio - return the priority value of a given task.
6029 * @p: the task in question.
6030 *
6031 * This is the priority value as seen by users in /proc.
6032 * RT tasks are offset by -200. Normal tasks are centered
6033 * around 0, value goes from -16 to +15.
6034 */
6035 int task_prio(const struct task_struct *p)
6036 {
6037 return p->prio - MAX_RT_PRIO;
6038 }
6039
6040 /**
6041 * task_nice - return the nice value of a given task.
6042 * @p: the task in question.
6043 */
6044 int task_nice(const struct task_struct *p)
6045 {
6046 return TASK_NICE(p);
6047 }
6048 EXPORT_SYMBOL(task_nice);
6049
6050 /**
6051 * idle_cpu - is a given cpu idle currently?
6052 * @cpu: the processor in question.
6053 */
6054 int idle_cpu(int cpu)
6055 {
6056 return cpu_curr(cpu) == cpu_rq(cpu)->idle;
6057 }
6058
6059 /**
6060 * idle_task - return the idle task for a given cpu.
6061 * @cpu: the processor in question.
6062 */
6063 struct task_struct *idle_task(int cpu)
6064 {
6065 return cpu_rq(cpu)->idle;
6066 }
6067
6068 /**
6069 * find_process_by_pid - find a process with a matching PID value.
6070 * @pid: the pid in question.
6071 */
6072 static struct task_struct *find_process_by_pid(pid_t pid)
6073 {
6074 return pid ? find_task_by_vpid(pid) : current;
6075 }
6076
6077 /* Actually do priority change: must hold rq lock. */
6078 static void
6079 __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
6080 {
6081 BUG_ON(p->se.on_rq);
6082
6083 p->policy = policy;
6084 switch (p->policy) {
6085 case SCHED_NORMAL:
6086 case SCHED_BATCH:
6087 case SCHED_IDLE:
6088 p->sched_class = &fair_sched_class;
6089 break;
6090 case SCHED_FIFO:
6091 case SCHED_RR:
6092 p->sched_class = &rt_sched_class;
6093 break;
6094 }
6095
6096 p->rt_priority = prio;
6097 p->normal_prio = normal_prio(p);
6098 /* we are holding p->pi_lock already */
6099 p->prio = rt_mutex_getprio(p);
6100 set_load_weight(p);
6101 }
6102
6103 /*
6104 * check the target process has a UID that matches the current process's
6105 */
6106 static bool check_same_owner(struct task_struct *p)
6107 {
6108 const struct cred *cred = current_cred(), *pcred;
6109 bool match;
6110
6111 rcu_read_lock();
6112 pcred = __task_cred(p);
6113 match = (cred->euid == pcred->euid ||
6114 cred->euid == pcred->uid);
6115 rcu_read_unlock();
6116 return match;
6117 }
6118
6119 static int __sched_setscheduler(struct task_struct *p, int policy,
6120 struct sched_param *param, bool user)
6121 {
6122 int retval, oldprio, oldpolicy = -1, on_rq, running;
6123 unsigned long flags;
6124 const struct sched_class *prev_class = p->sched_class;
6125 struct rq *rq;
6126
6127 /* may grab non-irq protected spin_locks */
6128 BUG_ON(in_interrupt());
6129 recheck:
6130 /* double check policy once rq lock held */
6131 if (policy < 0)
6132 policy = oldpolicy = p->policy;
6133 else if (policy != SCHED_FIFO && policy != SCHED_RR &&
6134 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
6135 policy != SCHED_IDLE)
6136 return -EINVAL;
6137 /*
6138 * Valid priorities for SCHED_FIFO and SCHED_RR are
6139 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
6140 * SCHED_BATCH and SCHED_IDLE is 0.
6141 */
6142 if (param->sched_priority < 0 ||
6143 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
6144 (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
6145 return -EINVAL;
6146 if (rt_policy(policy) != (param->sched_priority != 0))
6147 return -EINVAL;
6148
6149 /*
6150 * Allow unprivileged RT tasks to decrease priority:
6151 */
6152 if (user && !capable(CAP_SYS_NICE)) {
6153 if (rt_policy(policy)) {
6154 unsigned long rlim_rtprio;
6155
6156 if (!lock_task_sighand(p, &flags))
6157 return -ESRCH;
6158 rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
6159 unlock_task_sighand(p, &flags);
6160
6161 /* can't set/change the rt policy */
6162 if (policy != p->policy && !rlim_rtprio)
6163 return -EPERM;
6164
6165 /* can't increase priority */
6166 if (param->sched_priority > p->rt_priority &&
6167 param->sched_priority > rlim_rtprio)
6168 return -EPERM;
6169 }
6170 /*
6171 * Like positive nice levels, dont allow tasks to
6172 * move out of SCHED_IDLE either:
6173 */
6174 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE)
6175 return -EPERM;
6176
6177 /* can't change other user's priorities */
6178 if (!check_same_owner(p))
6179 return -EPERM;
6180 }
6181
6182 if (user) {
6183 #ifdef CONFIG_RT_GROUP_SCHED
6184 /*
6185 * Do not allow realtime tasks into groups that have no runtime
6186 * assigned.
6187 */
6188 if (rt_bandwidth_enabled() && rt_policy(policy) &&
6189 task_group(p)->rt_bandwidth.rt_runtime == 0)
6190 return -EPERM;
6191 #endif
6192
6193 retval = security_task_setscheduler(p, policy, param);
6194 if (retval)
6195 return retval;
6196 }
6197
6198 /*
6199 * make sure no PI-waiters arrive (or leave) while we are
6200 * changing the priority of the task:
6201 */
6202 spin_lock_irqsave(&p->pi_lock, flags);
6203 /*
6204 * To be able to change p->policy safely, the apropriate
6205 * runqueue lock must be held.
6206 */
6207 rq = __task_rq_lock(p);
6208 /* recheck policy now with rq lock held */
6209 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
6210 policy = oldpolicy = -1;
6211 __task_rq_unlock(rq);
6212 spin_unlock_irqrestore(&p->pi_lock, flags);
6213 goto recheck;
6214 }
6215 update_rq_clock(rq);
6216 on_rq = p->se.on_rq;
6217 running = task_current(rq, p);
6218 if (on_rq)
6219 deactivate_task(rq, p, 0);
6220 if (running)
6221 p->sched_class->put_prev_task(rq, p);
6222
6223 oldprio = p->prio;
6224 __setscheduler(rq, p, policy, param->sched_priority);
6225
6226 if (running)
6227 p->sched_class->set_curr_task(rq);
6228 if (on_rq) {
6229 activate_task(rq, p, 0);
6230
6231 check_class_changed(rq, p, prev_class, oldprio, running);
6232 }
6233 __task_rq_unlock(rq);
6234 spin_unlock_irqrestore(&p->pi_lock, flags);
6235
6236 rt_mutex_adjust_pi(p);
6237
6238 return 0;
6239 }
6240
6241 /**
6242 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
6243 * @p: the task in question.
6244 * @policy: new policy.
6245 * @param: structure containing the new RT priority.
6246 *
6247 * NOTE that the task may be already dead.
6248 */
6249 int sched_setscheduler(struct task_struct *p, int policy,
6250 struct sched_param *param)
6251 {
6252 return __sched_setscheduler(p, policy, param, true);
6253 }
6254 EXPORT_SYMBOL_GPL(sched_setscheduler);
6255
6256 /**
6257 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
6258 * @p: the task in question.
6259 * @policy: new policy.
6260 * @param: structure containing the new RT priority.
6261 *
6262 * Just like sched_setscheduler, only don't bother checking if the
6263 * current context has permission. For example, this is needed in
6264 * stop_machine(): we create temporary high priority worker threads,
6265 * but our caller might not have that capability.
6266 */
6267 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
6268 struct sched_param *param)
6269 {
6270 return __sched_setscheduler(p, policy, param, false);
6271 }
6272
6273 static int
6274 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
6275 {
6276 struct sched_param lparam;
6277 struct task_struct *p;
6278 int retval;
6279
6280 if (!param || pid < 0)
6281 return -EINVAL;
6282 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
6283 return -EFAULT;
6284
6285 rcu_read_lock();
6286 retval = -ESRCH;
6287 p = find_process_by_pid(pid);
6288 if (p != NULL)
6289 retval = sched_setscheduler(p, policy, &lparam);
6290 rcu_read_unlock();
6291
6292 return retval;
6293 }
6294
6295 /**
6296 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
6297 * @pid: the pid in question.
6298 * @policy: new policy.
6299 * @param: structure containing the new RT priority.
6300 */
6301 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
6302 struct sched_param __user *, param)
6303 {
6304 /* negative values for policy are not valid */
6305 if (policy < 0)
6306 return -EINVAL;
6307
6308 return do_sched_setscheduler(pid, policy, param);
6309 }
6310
6311 /**
6312 * sys_sched_setparam - set/change the RT priority of a thread
6313 * @pid: the pid in question.
6314 * @param: structure containing the new RT priority.
6315 */
6316 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
6317 {
6318 return do_sched_setscheduler(pid, -1, param);
6319 }
6320
6321 /**
6322 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
6323 * @pid: the pid in question.
6324 */
6325 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
6326 {
6327 struct task_struct *p;
6328 int retval;
6329
6330 if (pid < 0)
6331 return -EINVAL;
6332
6333 retval = -ESRCH;
6334 read_lock(&tasklist_lock);
6335 p = find_process_by_pid(pid);
6336 if (p) {
6337 retval = security_task_getscheduler(p);
6338 if (!retval)
6339 retval = p->policy;
6340 }
6341 read_unlock(&tasklist_lock);
6342 return retval;
6343 }
6344
6345 /**
6346 * sys_sched_getscheduler - get the RT priority of a thread
6347 * @pid: the pid in question.
6348 * @param: structure containing the RT priority.
6349 */
6350 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
6351 {
6352 struct sched_param lp;
6353 struct task_struct *p;
6354 int retval;
6355
6356 if (!param || pid < 0)
6357 return -EINVAL;
6358
6359 read_lock(&tasklist_lock);
6360 p = find_process_by_pid(pid);
6361 retval = -ESRCH;
6362 if (!p)
6363 goto out_unlock;
6364
6365 retval = security_task_getscheduler(p);
6366 if (retval)
6367 goto out_unlock;
6368
6369 lp.sched_priority = p->rt_priority;
6370 read_unlock(&tasklist_lock);
6371
6372 /*
6373 * This one might sleep, we cannot do it with a spinlock held ...
6374 */
6375 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
6376
6377 return retval;
6378
6379 out_unlock:
6380 read_unlock(&tasklist_lock);
6381 return retval;
6382 }
6383
6384 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
6385 {
6386 cpumask_var_t cpus_allowed, new_mask;
6387 struct task_struct *p;
6388 int retval;
6389
6390 get_online_cpus();
6391 read_lock(&tasklist_lock);
6392
6393 p = find_process_by_pid(pid);
6394 if (!p) {
6395 read_unlock(&tasklist_lock);
6396 put_online_cpus();
6397 return -ESRCH;
6398 }
6399
6400 /*
6401 * It is not safe to call set_cpus_allowed with the
6402 * tasklist_lock held. We will bump the task_struct's
6403 * usage count and then drop tasklist_lock.
6404 */
6405 get_task_struct(p);
6406 read_unlock(&tasklist_lock);
6407
6408 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
6409 retval = -ENOMEM;
6410 goto out_put_task;
6411 }
6412 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
6413 retval = -ENOMEM;
6414 goto out_free_cpus_allowed;
6415 }
6416 retval = -EPERM;
6417 if (!check_same_owner(p) && !capable(CAP_SYS_NICE))
6418 goto out_unlock;
6419
6420 retval = security_task_setscheduler(p, 0, NULL);
6421 if (retval)
6422 goto out_unlock;
6423
6424 cpuset_cpus_allowed(p, cpus_allowed);
6425 cpumask_and(new_mask, in_mask, cpus_allowed);
6426 again:
6427 retval = set_cpus_allowed_ptr(p, new_mask);
6428
6429 if (!retval) {
6430 cpuset_cpus_allowed(p, cpus_allowed);
6431 if (!cpumask_subset(new_mask, cpus_allowed)) {
6432 /*
6433 * We must have raced with a concurrent cpuset
6434 * update. Just reset the cpus_allowed to the
6435 * cpuset's cpus_allowed
6436 */
6437 cpumask_copy(new_mask, cpus_allowed);
6438 goto again;
6439 }
6440 }
6441 out_unlock:
6442 free_cpumask_var(new_mask);
6443 out_free_cpus_allowed:
6444 free_cpumask_var(cpus_allowed);
6445 out_put_task:
6446 put_task_struct(p);
6447 put_online_cpus();
6448 return retval;
6449 }
6450
6451 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
6452 struct cpumask *new_mask)
6453 {
6454 if (len < cpumask_size())
6455 cpumask_clear(new_mask);
6456 else if (len > cpumask_size())
6457 len = cpumask_size();
6458
6459 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
6460 }
6461
6462 /**
6463 * sys_sched_setaffinity - set the cpu affinity of a process
6464 * @pid: pid of the process
6465 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
6466 * @user_mask_ptr: user-space pointer to the new cpu mask
6467 */
6468 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
6469 unsigned long __user *, user_mask_ptr)
6470 {
6471 cpumask_var_t new_mask;
6472 int retval;
6473
6474 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
6475 return -ENOMEM;
6476
6477 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
6478 if (retval == 0)
6479 retval = sched_setaffinity(pid, new_mask);
6480 free_cpumask_var(new_mask);
6481 return retval;
6482 }
6483
6484 long sched_getaffinity(pid_t pid, struct cpumask *mask)
6485 {
6486 struct task_struct *p;
6487 int retval;
6488
6489 get_online_cpus();
6490 read_lock(&tasklist_lock);
6491
6492 retval = -ESRCH;
6493 p = find_process_by_pid(pid);
6494 if (!p)
6495 goto out_unlock;
6496
6497 retval = security_task_getscheduler(p);
6498 if (retval)
6499 goto out_unlock;
6500
6501 cpumask_and(mask, &p->cpus_allowed, cpu_online_mask);
6502
6503 out_unlock:
6504 read_unlock(&tasklist_lock);
6505 put_online_cpus();
6506
6507 return retval;
6508 }
6509
6510 /**
6511 * sys_sched_getaffinity - get the cpu affinity of a process
6512 * @pid: pid of the process
6513 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
6514 * @user_mask_ptr: user-space pointer to hold the current cpu mask
6515 */
6516 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
6517 unsigned long __user *, user_mask_ptr)
6518 {
6519 int ret;
6520 cpumask_var_t mask;
6521
6522 if (len < cpumask_size())
6523 return -EINVAL;
6524
6525 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
6526 return -ENOMEM;
6527
6528 ret = sched_getaffinity(pid, mask);
6529 if (ret == 0) {
6530 if (copy_to_user(user_mask_ptr, mask, cpumask_size()))
6531 ret = -EFAULT;
6532 else
6533 ret = cpumask_size();
6534 }
6535 free_cpumask_var(mask);
6536
6537 return ret;
6538 }
6539
6540 /**
6541 * sys_sched_yield - yield the current processor to other threads.
6542 *
6543 * This function yields the current CPU to other tasks. If there are no
6544 * other threads running on this CPU then this function will return.
6545 */
6546 SYSCALL_DEFINE0(sched_yield)
6547 {
6548 struct rq *rq = this_rq_lock();
6549
6550 schedstat_inc(rq, yld_count);
6551 current->sched_class->yield_task(rq);
6552
6553 /*
6554 * Since we are going to call schedule() anyway, there's
6555 * no need to preempt or enable interrupts:
6556 */
6557 __release(rq->lock);
6558 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
6559 _raw_spin_unlock(&rq->lock);
6560 preempt_enable_no_resched();
6561
6562 schedule();
6563
6564 return 0;
6565 }
6566
6567 static inline int should_resched(void)
6568 {
6569 return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
6570 }
6571
6572 static void __cond_resched(void)
6573 {
6574 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6575 __might_sleep(__FILE__, __LINE__);
6576 #endif
6577 /*
6578 * The BKS might be reacquired before we have dropped
6579 * PREEMPT_ACTIVE, which could trigger a second
6580 * cond_resched() call.
6581 */
6582 do {
6583 add_preempt_count(PREEMPT_ACTIVE);
6584 schedule();
6585 sub_preempt_count(PREEMPT_ACTIVE);
6586 } while (need_resched());
6587 }
6588
6589 int __sched _cond_resched(void)
6590 {
6591 if (should_resched()) {
6592 __cond_resched();
6593 return 1;
6594 }
6595 return 0;
6596 }
6597 EXPORT_SYMBOL(_cond_resched);
6598
6599 /*
6600 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
6601 * call schedule, and on return reacquire the lock.
6602 *
6603 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
6604 * operations here to prevent schedule() from being called twice (once via
6605 * spin_unlock(), once by hand).
6606 */
6607 int cond_resched_lock(spinlock_t *lock)
6608 {
6609 int resched = should_resched();
6610 int ret = 0;
6611
6612 if (spin_needbreak(lock) || resched) {
6613 spin_unlock(lock);
6614 if (resched)
6615 __cond_resched();
6616 else
6617 cpu_relax();
6618 ret = 1;
6619 spin_lock(lock);
6620 }
6621 return ret;
6622 }
6623 EXPORT_SYMBOL(cond_resched_lock);
6624
6625 int __sched cond_resched_softirq(void)
6626 {
6627 BUG_ON(!in_softirq());
6628
6629 if (should_resched()) {
6630 local_bh_enable();
6631 __cond_resched();
6632 local_bh_disable();
6633 return 1;
6634 }
6635 return 0;
6636 }
6637 EXPORT_SYMBOL(cond_resched_softirq);
6638
6639 /**
6640 * yield - yield the current processor to other threads.
6641 *
6642 * This is a shortcut for kernel-space yielding - it marks the
6643 * thread runnable and calls sys_sched_yield().
6644 */
6645 void __sched yield(void)
6646 {
6647 set_current_state(TASK_RUNNING);
6648 sys_sched_yield();
6649 }
6650 EXPORT_SYMBOL(yield);
6651
6652 /*
6653 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
6654 * that process accounting knows that this is a task in IO wait state.
6655 *
6656 * But don't do that if it is a deliberate, throttling IO wait (this task
6657 * has set its backing_dev_info: the queue against which it should throttle)
6658 */
6659 void __sched io_schedule(void)
6660 {
6661 struct rq *rq = &__raw_get_cpu_var(runqueues);
6662
6663 delayacct_blkio_start();
6664 atomic_inc(&rq->nr_iowait);
6665 schedule();
6666 atomic_dec(&rq->nr_iowait);
6667 delayacct_blkio_end();
6668 }
6669 EXPORT_SYMBOL(io_schedule);
6670
6671 long __sched io_schedule_timeout(long timeout)
6672 {
6673 struct rq *rq = &__raw_get_cpu_var(runqueues);
6674 long ret;
6675
6676 delayacct_blkio_start();
6677 atomic_inc(&rq->nr_iowait);
6678 ret = schedule_timeout(timeout);
6679 atomic_dec(&rq->nr_iowait);
6680 delayacct_blkio_end();
6681 return ret;
6682 }
6683
6684 /**
6685 * sys_sched_get_priority_max - return maximum RT priority.
6686 * @policy: scheduling class.
6687 *
6688 * this syscall returns the maximum rt_priority that can be used
6689 * by a given scheduling class.
6690 */
6691 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
6692 {
6693 int ret = -EINVAL;
6694
6695 switch (policy) {
6696 case SCHED_FIFO:
6697 case SCHED_RR:
6698 ret = MAX_USER_RT_PRIO-1;
6699 break;
6700 case SCHED_NORMAL:
6701 case SCHED_BATCH:
6702 case SCHED_IDLE:
6703 ret = 0;
6704 break;
6705 }
6706 return ret;
6707 }
6708
6709 /**
6710 * sys_sched_get_priority_min - return minimum RT priority.
6711 * @policy: scheduling class.
6712 *
6713 * this syscall returns the minimum rt_priority that can be used
6714 * by a given scheduling class.
6715 */
6716 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
6717 {
6718 int ret = -EINVAL;
6719
6720 switch (policy) {
6721 case SCHED_FIFO:
6722 case SCHED_RR:
6723 ret = 1;
6724 break;
6725 case SCHED_NORMAL:
6726 case SCHED_BATCH:
6727 case SCHED_IDLE:
6728 ret = 0;
6729 }
6730 return ret;
6731 }
6732
6733 /**
6734 * sys_sched_rr_get_interval - return the default timeslice of a process.
6735 * @pid: pid of the process.
6736 * @interval: userspace pointer to the timeslice value.
6737 *
6738 * this syscall writes the default timeslice value of a given process
6739 * into the user-space timespec buffer. A value of '0' means infinity.
6740 */
6741 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
6742 struct timespec __user *, interval)
6743 {
6744 struct task_struct *p;
6745 unsigned int time_slice;
6746 int retval;
6747 struct timespec t;
6748
6749 if (pid < 0)
6750 return -EINVAL;
6751
6752 retval = -ESRCH;
6753 read_lock(&tasklist_lock);
6754 p = find_process_by_pid(pid);
6755 if (!p)
6756 goto out_unlock;
6757
6758 retval = security_task_getscheduler(p);
6759 if (retval)
6760 goto out_unlock;
6761
6762 /*
6763 * Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER
6764 * tasks that are on an otherwise idle runqueue:
6765 */
6766 time_slice = 0;
6767 if (p->policy == SCHED_RR) {
6768 time_slice = DEF_TIMESLICE;
6769 } else if (p->policy != SCHED_FIFO) {
6770 struct sched_entity *se = &p->se;
6771 unsigned long flags;
6772 struct rq *rq;
6773
6774 rq = task_rq_lock(p, &flags);
6775 if (rq->cfs.load.weight)
6776 time_slice = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
6777 task_rq_unlock(rq, &flags);
6778 }
6779 read_unlock(&tasklist_lock);
6780 jiffies_to_timespec(time_slice, &t);
6781 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
6782 return retval;
6783
6784 out_unlock:
6785 read_unlock(&tasklist_lock);
6786 return retval;
6787 }
6788
6789 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
6790
6791 void sched_show_task(struct task_struct *p)
6792 {
6793 unsigned long free = 0;
6794 unsigned state;
6795
6796 state = p->state ? __ffs(p->state) + 1 : 0;
6797 printk(KERN_INFO "%-13.13s %c", p->comm,
6798 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
6799 #if BITS_PER_LONG == 32
6800 if (state == TASK_RUNNING)
6801 printk(KERN_CONT " running ");
6802 else
6803 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
6804 #else
6805 if (state == TASK_RUNNING)
6806 printk(KERN_CONT " running task ");
6807 else
6808 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
6809 #endif
6810 #ifdef CONFIG_DEBUG_STACK_USAGE
6811 free = stack_not_used(p);
6812 #endif
6813 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
6814 task_pid_nr(p), task_pid_nr(p->real_parent),
6815 (unsigned long)task_thread_info(p)->flags);
6816
6817 show_stack(p, NULL);
6818 }
6819
6820 void show_state_filter(unsigned long state_filter)
6821 {
6822 struct task_struct *g, *p;
6823
6824 #if BITS_PER_LONG == 32
6825 printk(KERN_INFO
6826 " task PC stack pid father\n");
6827 #else
6828 printk(KERN_INFO
6829 " task PC stack pid father\n");
6830 #endif
6831 read_lock(&tasklist_lock);
6832 do_each_thread(g, p) {
6833 /*
6834 * reset the NMI-timeout, listing all files on a slow
6835 * console might take alot of time:
6836 */
6837 touch_nmi_watchdog();
6838 if (!state_filter || (p->state & state_filter))
6839 sched_show_task(p);
6840 } while_each_thread(g, p);
6841
6842 touch_all_softlockup_watchdogs();
6843
6844 #ifdef CONFIG_SCHED_DEBUG
6845 sysrq_sched_debug_show();
6846 #endif
6847 read_unlock(&tasklist_lock);
6848 /*
6849 * Only show locks if all tasks are dumped:
6850 */
6851 if (state_filter == -1)
6852 debug_show_all_locks();
6853 }
6854
6855 void __cpuinit init_idle_bootup_task(struct task_struct *idle)
6856 {
6857 idle->sched_class = &idle_sched_class;
6858 }
6859
6860 /**
6861 * init_idle - set up an idle thread for a given CPU
6862 * @idle: task in question
6863 * @cpu: cpu the idle task belongs to
6864 *
6865 * NOTE: this function does not set the idle thread's NEED_RESCHED
6866 * flag, to make booting more robust.
6867 */
6868 void __cpuinit init_idle(struct task_struct *idle, int cpu)
6869 {
6870 struct rq *rq = cpu_rq(cpu);
6871 unsigned long flags;
6872
6873 spin_lock_irqsave(&rq->lock, flags);
6874
6875 __sched_fork(idle);
6876 idle->se.exec_start = sched_clock();
6877
6878 idle->prio = idle->normal_prio = MAX_PRIO;
6879 cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu));
6880 __set_task_cpu(idle, cpu);
6881
6882 rq->curr = rq->idle = idle;
6883 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
6884 idle->oncpu = 1;
6885 #endif
6886 spin_unlock_irqrestore(&rq->lock, flags);
6887
6888 /* Set the preempt count _outside_ the spinlocks! */
6889 #if defined(CONFIG_PREEMPT)
6890 task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
6891 #else
6892 task_thread_info(idle)->preempt_count = 0;
6893 #endif
6894 /*
6895 * The idle tasks have their own, simple scheduling class:
6896 */
6897 idle->sched_class = &idle_sched_class;
6898 ftrace_graph_init_task(idle);
6899 }
6900
6901 /*
6902 * In a system that switches off the HZ timer nohz_cpu_mask
6903 * indicates which cpus entered this state. This is used
6904 * in the rcu update to wait only for active cpus. For system
6905 * which do not switch off the HZ timer nohz_cpu_mask should
6906 * always be CPU_BITS_NONE.
6907 */
6908 cpumask_var_t nohz_cpu_mask;
6909
6910 /*
6911 * Increase the granularity value when there are more CPUs,
6912 * because with more CPUs the 'effective latency' as visible
6913 * to users decreases. But the relationship is not linear,
6914 * so pick a second-best guess by going with the log2 of the
6915 * number of CPUs.
6916 *
6917 * This idea comes from the SD scheduler of Con Kolivas:
6918 */
6919 static inline void sched_init_granularity(void)
6920 {
6921 unsigned int factor = 1 + ilog2(num_online_cpus());
6922 const unsigned long limit = 200000000;
6923
6924 sysctl_sched_min_granularity *= factor;
6925 if (sysctl_sched_min_granularity > limit)
6926 sysctl_sched_min_granularity = limit;
6927
6928 sysctl_sched_latency *= factor;
6929 if (sysctl_sched_latency > limit)
6930 sysctl_sched_latency = limit;
6931
6932 sysctl_sched_wakeup_granularity *= factor;
6933
6934 sysctl_sched_shares_ratelimit *= factor;
6935 }
6936
6937 #ifdef CONFIG_SMP
6938 /*
6939 * This is how migration works:
6940 *
6941 * 1) we queue a struct migration_req structure in the source CPU's
6942 * runqueue and wake up that CPU's migration thread.
6943 * 2) we down() the locked semaphore => thread blocks.
6944 * 3) migration thread wakes up (implicitly it forces the migrated
6945 * thread off the CPU)
6946 * 4) it gets the migration request and checks whether the migrated
6947 * task is still in the wrong runqueue.
6948 * 5) if it's in the wrong runqueue then the migration thread removes
6949 * it and puts it into the right queue.
6950 * 6) migration thread up()s the semaphore.
6951 * 7) we wake up and the migration is done.
6952 */
6953
6954 /*
6955 * Change a given task's CPU affinity. Migrate the thread to a
6956 * proper CPU and schedule it away if the CPU it's executing on
6957 * is removed from the allowed bitmask.
6958 *
6959 * NOTE: the caller must have a valid reference to the task, the
6960 * task must not exit() & deallocate itself prematurely. The
6961 * call is not atomic; no spinlocks may be held.
6962 */
6963 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
6964 {
6965 struct migration_req req;
6966 unsigned long flags;
6967 struct rq *rq;
6968 int ret = 0;
6969
6970 rq = task_rq_lock(p, &flags);
6971 if (!cpumask_intersects(new_mask, cpu_online_mask)) {
6972 ret = -EINVAL;
6973 goto out;
6974 }
6975
6976 if (unlikely((p->flags & PF_THREAD_BOUND) && p != current &&
6977 !cpumask_equal(&p->cpus_allowed, new_mask))) {
6978 ret = -EINVAL;
6979 goto out;
6980 }
6981
6982 if (p->sched_class->set_cpus_allowed)
6983 p->sched_class->set_cpus_allowed(p, new_mask);
6984 else {
6985 cpumask_copy(&p->cpus_allowed, new_mask);
6986 p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
6987 }
6988
6989 /* Can the task run on the task's current CPU? If so, we're done */
6990 if (cpumask_test_cpu(task_cpu(p), new_mask))
6991 goto out;
6992
6993 if (migrate_task(p, cpumask_any_and(cpu_online_mask, new_mask), &req)) {
6994 /* Need help from migration thread: drop lock and wait. */
6995 task_rq_unlock(rq, &flags);
6996 wake_up_process(rq->migration_thread);
6997 wait_for_completion(&req.done);
6998 tlb_migrate_finish(p->mm);
6999 return 0;
7000 }
7001 out:
7002 task_rq_unlock(rq, &flags);
7003
7004 return ret;
7005 }
7006 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
7007
7008 /*
7009 * Move (not current) task off this cpu, onto dest cpu. We're doing
7010 * this because either it can't run here any more (set_cpus_allowed()
7011 * away from this CPU, or CPU going down), or because we're
7012 * attempting to rebalance this task on exec (sched_exec).
7013 *
7014 * So we race with normal scheduler movements, but that's OK, as long
7015 * as the task is no longer on this CPU.
7016 *
7017 * Returns non-zero if task was successfully migrated.
7018 */
7019 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
7020 {
7021 struct rq *rq_dest, *rq_src;
7022 int ret = 0, on_rq;
7023
7024 if (unlikely(!cpu_active(dest_cpu)))
7025 return ret;
7026
7027 rq_src = cpu_rq(src_cpu);
7028 rq_dest = cpu_rq(dest_cpu);
7029
7030 double_rq_lock(rq_src, rq_dest);
7031 /* Already moved. */
7032 if (task_cpu(p) != src_cpu)
7033 goto done;
7034 /* Affinity changed (again). */
7035 if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
7036 goto fail;
7037
7038 on_rq = p->se.on_rq;
7039 if (on_rq)
7040 deactivate_task(rq_src, p, 0);
7041
7042 set_task_cpu(p, dest_cpu);
7043 if (on_rq) {
7044 activate_task(rq_dest, p, 0);
7045 check_preempt_curr(rq_dest, p, 0);
7046 }
7047 done:
7048 ret = 1;
7049 fail:
7050 double_rq_unlock(rq_src, rq_dest);
7051 return ret;
7052 }
7053
7054 /*
7055 * migration_thread - this is a highprio system thread that performs
7056 * thread migration by bumping thread off CPU then 'pushing' onto
7057 * another runqueue.
7058 */
7059 static int migration_thread(void *data)
7060 {
7061 int cpu = (long)data;
7062 struct rq *rq;
7063
7064 rq = cpu_rq(cpu);
7065 BUG_ON(rq->migration_thread != current);
7066
7067 set_current_state(TASK_INTERRUPTIBLE);
7068 while (!kthread_should_stop()) {
7069 struct migration_req *req;
7070 struct list_head *head;
7071
7072 spin_lock_irq(&rq->lock);
7073
7074 if (cpu_is_offline(cpu)) {
7075 spin_unlock_irq(&rq->lock);
7076 break;
7077 }
7078
7079 if (rq->active_balance) {
7080 active_load_balance(rq, cpu);
7081 rq->active_balance = 0;
7082 }
7083
7084 head = &rq->migration_queue;
7085
7086 if (list_empty(head)) {
7087 spin_unlock_irq(&rq->lock);
7088 schedule();
7089 set_current_state(TASK_INTERRUPTIBLE);
7090 continue;
7091 }
7092 req = list_entry(head->next, struct migration_req, list);
7093 list_del_init(head->next);
7094
7095 spin_unlock(&rq->lock);
7096 __migrate_task(req->task, cpu, req->dest_cpu);
7097 local_irq_enable();
7098
7099 complete(&req->done);
7100 }
7101 __set_current_state(TASK_RUNNING);
7102
7103 return 0;
7104 }
7105
7106 #ifdef CONFIG_HOTPLUG_CPU
7107
7108 static int __migrate_task_irq(struct task_struct *p, int src_cpu, int dest_cpu)
7109 {
7110 int ret;
7111
7112 local_irq_disable();
7113 ret = __migrate_task(p, src_cpu, dest_cpu);
7114 local_irq_enable();
7115 return ret;
7116 }
7117
7118 /*
7119 * Figure out where task on dead CPU should go, use force if necessary.
7120 */
7121 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
7122 {
7123 int dest_cpu;
7124 const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(dead_cpu));
7125
7126 again:
7127 /* Look for allowed, online CPU in same node. */
7128 for_each_cpu_and(dest_cpu, nodemask, cpu_online_mask)
7129 if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
7130 goto move;
7131
7132 /* Any allowed, online CPU? */
7133 dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_online_mask);
7134 if (dest_cpu < nr_cpu_ids)
7135 goto move;
7136
7137 /* No more Mr. Nice Guy. */
7138 if (dest_cpu >= nr_cpu_ids) {
7139 cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
7140 dest_cpu = cpumask_any_and(cpu_online_mask, &p->cpus_allowed);
7141
7142 /*
7143 * Don't tell them about moving exiting tasks or
7144 * kernel threads (both mm NULL), since they never
7145 * leave kernel.
7146 */
7147 if (p->mm && printk_ratelimit()) {
7148 printk(KERN_INFO "process %d (%s) no "
7149 "longer affine to cpu%d\n",
7150 task_pid_nr(p), p->comm, dead_cpu);
7151 }
7152 }
7153
7154 move:
7155 /* It can have affinity changed while we were choosing. */
7156 if (unlikely(!__migrate_task_irq(p, dead_cpu, dest_cpu)))
7157 goto again;
7158 }
7159
7160 /*
7161 * While a dead CPU has no uninterruptible tasks queued at this point,
7162 * it might still have a nonzero ->nr_uninterruptible counter, because
7163 * for performance reasons the counter is not stricly tracking tasks to
7164 * their home CPUs. So we just add the counter to another CPU's counter,
7165 * to keep the global sum constant after CPU-down:
7166 */
7167 static void migrate_nr_uninterruptible(struct rq *rq_src)
7168 {
7169 struct rq *rq_dest = cpu_rq(cpumask_any(cpu_online_mask));
7170 unsigned long flags;
7171
7172 local_irq_save(flags);
7173 double_rq_lock(rq_src, rq_dest);
7174 rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
7175 rq_src->nr_uninterruptible = 0;
7176 double_rq_unlock(rq_src, rq_dest);
7177 local_irq_restore(flags);
7178 }
7179
7180 /* Run through task list and migrate tasks from the dead cpu. */
7181 static void migrate_live_tasks(int src_cpu)
7182 {
7183 struct task_struct *p, *t;
7184
7185 read_lock(&tasklist_lock);
7186
7187 do_each_thread(t, p) {
7188 if (p == current)
7189 continue;
7190
7191 if (task_cpu(p) == src_cpu)
7192 move_task_off_dead_cpu(src_cpu, p);
7193 } while_each_thread(t, p);
7194
7195 read_unlock(&tasklist_lock);
7196 }
7197
7198 /*
7199 * Schedules idle task to be the next runnable task on current CPU.
7200 * It does so by boosting its priority to highest possible.
7201 * Used by CPU offline code.
7202 */
7203 void sched_idle_next(void)
7204 {
7205 int this_cpu = smp_processor_id();
7206 struct rq *rq = cpu_rq(this_cpu);
7207 struct task_struct *p = rq->idle;
7208 unsigned long flags;
7209
7210 /* cpu has to be offline */
7211 BUG_ON(cpu_online(this_cpu));
7212
7213 /*
7214 * Strictly not necessary since rest of the CPUs are stopped by now
7215 * and interrupts disabled on the current cpu.
7216 */
7217 spin_lock_irqsave(&rq->lock, flags);
7218
7219 __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
7220
7221 update_rq_clock(rq);
7222 activate_task(rq, p, 0);
7223
7224 spin_unlock_irqrestore(&rq->lock, flags);
7225 }
7226
7227 /*
7228 * Ensures that the idle task is using init_mm right before its cpu goes
7229 * offline.
7230 */
7231 void idle_task_exit(void)
7232 {
7233 struct mm_struct *mm = current->active_mm;
7234
7235 BUG_ON(cpu_online(smp_processor_id()));
7236
7237 if (mm != &init_mm)
7238 switch_mm(mm, &init_mm, current);
7239 mmdrop(mm);
7240 }
7241
7242 /* called under rq->lock with disabled interrupts */
7243 static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
7244 {
7245 struct rq *rq = cpu_rq(dead_cpu);
7246
7247 /* Must be exiting, otherwise would be on tasklist. */
7248 BUG_ON(!p->exit_state);
7249
7250 /* Cannot have done final schedule yet: would have vanished. */
7251 BUG_ON(p->state == TASK_DEAD);
7252
7253 get_task_struct(p);
7254
7255 /*
7256 * Drop lock around migration; if someone else moves it,
7257 * that's OK. No task can be added to this CPU, so iteration is
7258 * fine.
7259 */
7260 spin_unlock_irq(&rq->lock);
7261 move_task_off_dead_cpu(dead_cpu, p);
7262 spin_lock_irq(&rq->lock);
7263
7264 put_task_struct(p);
7265 }
7266
7267 /* release_task() removes task from tasklist, so we won't find dead tasks. */
7268 static void migrate_dead_tasks(unsigned int dead_cpu)
7269 {
7270 struct rq *rq = cpu_rq(dead_cpu);
7271 struct task_struct *next;
7272
7273 for ( ; ; ) {
7274 if (!rq->nr_running)
7275 break;
7276 update_rq_clock(rq);
7277 next = pick_next_task(rq);
7278 if (!next)
7279 break;
7280 next->sched_class->put_prev_task(rq, next);
7281 migrate_dead(dead_cpu, next);
7282
7283 }
7284 }
7285
7286 /*
7287 * remove the tasks which were accounted by rq from calc_load_tasks.
7288 */
7289 static void calc_global_load_remove(struct rq *rq)
7290 {
7291 atomic_long_sub(rq->calc_load_active, &calc_load_tasks);
7292 rq->calc_load_active = 0;
7293 }
7294 #endif /* CONFIG_HOTPLUG_CPU */
7295
7296 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
7297
7298 static struct ctl_table sd_ctl_dir[] = {
7299 {
7300 .procname = "sched_domain",
7301 .mode = 0555,
7302 },
7303 {0, },
7304 };
7305
7306 static struct ctl_table sd_ctl_root[] = {
7307 {
7308 .ctl_name = CTL_KERN,
7309 .procname = "kernel",
7310 .mode = 0555,
7311 .child = sd_ctl_dir,
7312 },
7313 {0, },
7314 };
7315
7316 static struct ctl_table *sd_alloc_ctl_entry(int n)
7317 {
7318 struct ctl_table *entry =
7319 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
7320
7321 return entry;
7322 }
7323
7324 static void sd_free_ctl_entry(struct ctl_table **tablep)
7325 {
7326 struct ctl_table *entry;
7327
7328 /*
7329 * In the intermediate directories, both the child directory and
7330 * procname are dynamically allocated and could fail but the mode
7331 * will always be set. In the lowest directory the names are
7332 * static strings and all have proc handlers.
7333 */
7334 for (entry = *tablep; entry->mode; entry++) {
7335 if (entry->child)
7336 sd_free_ctl_entry(&entry->child);
7337 if (entry->proc_handler == NULL)
7338 kfree(entry->procname);
7339 }
7340
7341 kfree(*tablep);
7342 *tablep = NULL;
7343 }
7344
7345 static void
7346 set_table_entry(struct ctl_table *entry,
7347 const char *procname, void *data, int maxlen,
7348 mode_t mode, proc_handler *proc_handler)
7349 {
7350 entry->procname = procname;
7351 entry->data = data;
7352 entry->maxlen = maxlen;
7353 entry->mode = mode;
7354 entry->proc_handler = proc_handler;
7355 }
7356
7357 static struct ctl_table *
7358 sd_alloc_ctl_domain_table(struct sched_domain *sd)
7359 {
7360 struct ctl_table *table = sd_alloc_ctl_entry(13);
7361
7362 if (table == NULL)
7363 return NULL;
7364
7365 set_table_entry(&table[0], "min_interval", &sd->min_interval,
7366 sizeof(long), 0644, proc_doulongvec_minmax);
7367 set_table_entry(&table[1], "max_interval", &sd->max_interval,
7368 sizeof(long), 0644, proc_doulongvec_minmax);
7369 set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
7370 sizeof(int), 0644, proc_dointvec_minmax);
7371 set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
7372 sizeof(int), 0644, proc_dointvec_minmax);
7373 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
7374 sizeof(int), 0644, proc_dointvec_minmax);
7375 set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
7376 sizeof(int), 0644, proc_dointvec_minmax);
7377 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
7378 sizeof(int), 0644, proc_dointvec_minmax);
7379 set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
7380 sizeof(int), 0644, proc_dointvec_minmax);
7381 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
7382 sizeof(int), 0644, proc_dointvec_minmax);
7383 set_table_entry(&table[9], "cache_nice_tries",
7384 &sd->cache_nice_tries,
7385 sizeof(int), 0644, proc_dointvec_minmax);
7386 set_table_entry(&table[10], "flags", &sd->flags,
7387 sizeof(int), 0644, proc_dointvec_minmax);
7388 set_table_entry(&table[11], "name", sd->name,
7389 CORENAME_MAX_SIZE, 0444, proc_dostring);
7390 /* &table[12] is terminator */
7391
7392 return table;
7393 }
7394
7395 static ctl_table *sd_alloc_ctl_cpu_table(int cpu)
7396 {
7397 struct ctl_table *entry, *table;
7398 struct sched_domain *sd;
7399 int domain_num = 0, i;
7400 char buf[32];
7401
7402 for_each_domain(cpu, sd)
7403 domain_num++;
7404 entry = table = sd_alloc_ctl_entry(domain_num + 1);
7405 if (table == NULL)
7406 return NULL;
7407
7408 i = 0;
7409 for_each_domain(cpu, sd) {
7410 snprintf(buf, 32, "domain%d", i);
7411 entry->procname = kstrdup(buf, GFP_KERNEL);
7412 entry->mode = 0555;
7413 entry->child = sd_alloc_ctl_domain_table(sd);
7414 entry++;
7415 i++;
7416 }
7417 return table;
7418 }
7419
7420 static struct ctl_table_header *sd_sysctl_header;
7421 static void register_sched_domain_sysctl(void)
7422 {
7423 int i, cpu_num = num_online_cpus();
7424 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
7425 char buf[32];
7426
7427 WARN_ON(sd_ctl_dir[0].child);
7428 sd_ctl_dir[0].child = entry;
7429
7430 if (entry == NULL)
7431 return;
7432
7433 for_each_online_cpu(i) {
7434 snprintf(buf, 32, "cpu%d", i);
7435 entry->procname = kstrdup(buf, GFP_KERNEL);
7436 entry->mode = 0555;
7437 entry->child = sd_alloc_ctl_cpu_table(i);
7438 entry++;
7439 }
7440
7441 WARN_ON(sd_sysctl_header);
7442 sd_sysctl_header = register_sysctl_table(sd_ctl_root);
7443 }
7444
7445 /* may be called multiple times per register */
7446 static void unregister_sched_domain_sysctl(void)
7447 {
7448 if (sd_sysctl_header)
7449 unregister_sysctl_table(sd_sysctl_header);
7450 sd_sysctl_header = NULL;
7451 if (sd_ctl_dir[0].child)
7452 sd_free_ctl_entry(&sd_ctl_dir[0].child);
7453 }
7454 #else
7455 static void register_sched_domain_sysctl(void)
7456 {
7457 }
7458 static void unregister_sched_domain_sysctl(void)
7459 {
7460 }
7461 #endif
7462
7463 static void set_rq_online(struct rq *rq)
7464 {
7465 if (!rq->online) {
7466 const struct sched_class *class;
7467
7468 cpumask_set_cpu(rq->cpu, rq->rd->online);
7469 rq->online = 1;
7470
7471 for_each_class(class) {
7472 if (class->rq_online)
7473 class->rq_online(rq);
7474 }
7475 }
7476 }
7477
7478 static void set_rq_offline(struct rq *rq)
7479 {
7480 if (rq->online) {
7481 const struct sched_class *class;
7482
7483 for_each_class(class) {
7484 if (class->rq_offline)
7485 class->rq_offline(rq);
7486 }
7487
7488 cpumask_clear_cpu(rq->cpu, rq->rd->online);
7489 rq->online = 0;
7490 }
7491 }
7492
7493 /*
7494 * migration_call - callback that gets triggered when a CPU is added.
7495 * Here we can start up the necessary migration thread for the new CPU.
7496 */
7497 static int __cpuinit
7498 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
7499 {
7500 struct task_struct *p;
7501 int cpu = (long)hcpu;
7502 unsigned long flags;
7503 struct rq *rq;
7504
7505 switch (action) {
7506
7507 case CPU_UP_PREPARE:
7508 case CPU_UP_PREPARE_FROZEN:
7509 p = kthread_create(migration_thread, hcpu, "migration/%d", cpu);
7510 if (IS_ERR(p))
7511 return NOTIFY_BAD;
7512 kthread_bind(p, cpu);
7513 /* Must be high prio: stop_machine expects to yield to it. */
7514 rq = task_rq_lock(p, &flags);
7515 __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
7516 task_rq_unlock(rq, &flags);
7517 get_task_struct(p);
7518 cpu_rq(cpu)->migration_thread = p;
7519 rq->calc_load_update = calc_load_update;
7520 break;
7521
7522 case CPU_ONLINE:
7523 case CPU_ONLINE_FROZEN:
7524 /* Strictly unnecessary, as first user will wake it. */
7525 wake_up_process(cpu_rq(cpu)->migration_thread);
7526
7527 /* Update our root-domain */
7528 rq = cpu_rq(cpu);
7529 spin_lock_irqsave(&rq->lock, flags);
7530 if (rq->rd) {
7531 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
7532
7533 set_rq_online(rq);
7534 }
7535 spin_unlock_irqrestore(&rq->lock, flags);
7536 break;
7537
7538 #ifdef CONFIG_HOTPLUG_CPU
7539 case CPU_UP_CANCELED:
7540 case CPU_UP_CANCELED_FROZEN:
7541 if (!cpu_rq(cpu)->migration_thread)
7542 break;
7543 /* Unbind it from offline cpu so it can run. Fall thru. */
7544 kthread_bind(cpu_rq(cpu)->migration_thread,
7545 cpumask_any(cpu_online_mask));
7546 kthread_stop(cpu_rq(cpu)->migration_thread);
7547 put_task_struct(cpu_rq(cpu)->migration_thread);
7548 cpu_rq(cpu)->migration_thread = NULL;
7549 break;
7550
7551 case CPU_DEAD:
7552 case CPU_DEAD_FROZEN:
7553 cpuset_lock(); /* around calls to cpuset_cpus_allowed_lock() */
7554 migrate_live_tasks(cpu);
7555 rq = cpu_rq(cpu);
7556 kthread_stop(rq->migration_thread);
7557 put_task_struct(rq->migration_thread);
7558 rq->migration_thread = NULL;
7559 /* Idle task back to normal (off runqueue, low prio) */
7560 spin_lock_irq(&rq->lock);
7561 update_rq_clock(rq);
7562 deactivate_task(rq, rq->idle, 0);
7563 rq->idle->static_prio = MAX_PRIO;
7564 __setscheduler(rq, rq->idle, SCHED_NORMAL, 0);
7565 rq->idle->sched_class = &idle_sched_class;
7566 migrate_dead_tasks(cpu);
7567 spin_unlock_irq(&rq->lock);
7568 cpuset_unlock();
7569 migrate_nr_uninterruptible(rq);
7570 BUG_ON(rq->nr_running != 0);
7571 calc_global_load_remove(rq);
7572 /*
7573 * No need to migrate the tasks: it was best-effort if
7574 * they didn't take sched_hotcpu_mutex. Just wake up
7575 * the requestors.
7576 */
7577 spin_lock_irq(&rq->lock);
7578 while (!list_empty(&rq->migration_queue)) {
7579 struct migration_req *req;
7580
7581 req = list_entry(rq->migration_queue.next,
7582 struct migration_req, list);
7583 list_del_init(&req->list);
7584 spin_unlock_irq(&rq->lock);
7585 complete(&req->done);
7586 spin_lock_irq(&rq->lock);
7587 }
7588 spin_unlock_irq(&rq->lock);
7589 break;
7590
7591 case CPU_DYING:
7592 case CPU_DYING_FROZEN:
7593 /* Update our root-domain */
7594 rq = cpu_rq(cpu);
7595 spin_lock_irqsave(&rq->lock, flags);
7596 if (rq->rd) {
7597 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
7598 set_rq_offline(rq);
7599 }
7600 spin_unlock_irqrestore(&rq->lock, flags);
7601 break;
7602 #endif
7603 }
7604 return NOTIFY_OK;
7605 }
7606
7607 /*
7608 * Register at high priority so that task migration (migrate_all_tasks)
7609 * happens before everything else. This has to be lower priority than
7610 * the notifier in the perf_counter subsystem, though.
7611 */
7612 static struct notifier_block __cpuinitdata migration_notifier = {
7613 .notifier_call = migration_call,
7614 .priority = 10
7615 };
7616
7617 static int __init migration_init(void)
7618 {
7619 void *cpu = (void *)(long)smp_processor_id();
7620 int err;
7621
7622 /* Start one for the boot CPU: */
7623 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
7624 BUG_ON(err == NOTIFY_BAD);
7625 migration_call(&migration_notifier, CPU_ONLINE, cpu);
7626 register_cpu_notifier(&migration_notifier);
7627
7628 return err;
7629 }
7630 early_initcall(migration_init);
7631 #endif
7632
7633 #ifdef CONFIG_SMP
7634
7635 #ifdef CONFIG_SCHED_DEBUG
7636
7637 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
7638 struct cpumask *groupmask)
7639 {
7640 struct sched_group *group = sd->groups;
7641 char str[256];
7642
7643 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
7644 cpumask_clear(groupmask);
7645
7646 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
7647
7648 if (!(sd->flags & SD_LOAD_BALANCE)) {
7649 printk("does not load-balance\n");
7650 if (sd->parent)
7651 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
7652 " has parent");
7653 return -1;
7654 }
7655
7656 printk(KERN_CONT "span %s level %s\n", str, sd->name);
7657
7658 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
7659 printk(KERN_ERR "ERROR: domain->span does not contain "
7660 "CPU%d\n", cpu);
7661 }
7662 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
7663 printk(KERN_ERR "ERROR: domain->groups does not contain"
7664 " CPU%d\n", cpu);
7665 }
7666
7667 printk(KERN_DEBUG "%*s groups:", level + 1, "");
7668 do {
7669 if (!group) {
7670 printk("\n");
7671 printk(KERN_ERR "ERROR: group is NULL\n");
7672 break;
7673 }
7674
7675 if (!group->__cpu_power) {
7676 printk(KERN_CONT "\n");
7677 printk(KERN_ERR "ERROR: domain->cpu_power not "
7678 "set\n");
7679 break;
7680 }
7681
7682 if (!cpumask_weight(sched_group_cpus(group))) {
7683 printk(KERN_CONT "\n");
7684 printk(KERN_ERR "ERROR: empty group\n");
7685 break;
7686 }
7687
7688 if (cpumask_intersects(groupmask, sched_group_cpus(group))) {
7689 printk(KERN_CONT "\n");
7690 printk(KERN_ERR "ERROR: repeated CPUs\n");
7691 break;
7692 }
7693
7694 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
7695
7696 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
7697
7698 printk(KERN_CONT " %s", str);
7699 if (group->__cpu_power != SCHED_LOAD_SCALE) {
7700 printk(KERN_CONT " (__cpu_power = %d)",
7701 group->__cpu_power);
7702 }
7703
7704 group = group->next;
7705 } while (group != sd->groups);
7706 printk(KERN_CONT "\n");
7707
7708 if (!cpumask_equal(sched_domain_span(sd), groupmask))
7709 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
7710
7711 if (sd->parent &&
7712 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
7713 printk(KERN_ERR "ERROR: parent span is not a superset "
7714 "of domain->span\n");
7715 return 0;
7716 }
7717
7718 static void sched_domain_debug(struct sched_domain *sd, int cpu)
7719 {
7720 cpumask_var_t groupmask;
7721 int level = 0;
7722
7723 if (!sd) {
7724 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
7725 return;
7726 }
7727
7728 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
7729
7730 if (!alloc_cpumask_var(&groupmask, GFP_KERNEL)) {
7731 printk(KERN_DEBUG "Cannot load-balance (out of memory)\n");
7732 return;
7733 }
7734
7735 for (;;) {
7736 if (sched_domain_debug_one(sd, cpu, level, groupmask))
7737 break;
7738 level++;
7739 sd = sd->parent;
7740 if (!sd)
7741 break;
7742 }
7743 free_cpumask_var(groupmask);
7744 }
7745 #else /* !CONFIG_SCHED_DEBUG */
7746 # define sched_domain_debug(sd, cpu) do { } while (0)
7747 #endif /* CONFIG_SCHED_DEBUG */
7748
7749 static int sd_degenerate(struct sched_domain *sd)
7750 {
7751 if (cpumask_weight(sched_domain_span(sd)) == 1)
7752 return 1;
7753
7754 /* Following flags need at least 2 groups */
7755 if (sd->flags & (SD_LOAD_BALANCE |
7756 SD_BALANCE_NEWIDLE |
7757 SD_BALANCE_FORK |
7758 SD_BALANCE_EXEC |
7759 SD_SHARE_CPUPOWER |
7760 SD_SHARE_PKG_RESOURCES)) {
7761 if (sd->groups != sd->groups->next)
7762 return 0;
7763 }
7764
7765 /* Following flags don't use groups */
7766 if (sd->flags & (SD_WAKE_IDLE |
7767 SD_WAKE_AFFINE |
7768 SD_WAKE_BALANCE))
7769 return 0;
7770
7771 return 1;
7772 }
7773
7774 static int
7775 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
7776 {
7777 unsigned long cflags = sd->flags, pflags = parent->flags;
7778
7779 if (sd_degenerate(parent))
7780 return 1;
7781
7782 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
7783 return 0;
7784
7785 /* Does parent contain flags not in child? */
7786 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
7787 if (cflags & SD_WAKE_AFFINE)
7788 pflags &= ~SD_WAKE_BALANCE;
7789 /* Flags needing groups don't count if only 1 group in parent */
7790 if (parent->groups == parent->groups->next) {
7791 pflags &= ~(SD_LOAD_BALANCE |
7792 SD_BALANCE_NEWIDLE |
7793 SD_BALANCE_FORK |
7794 SD_BALANCE_EXEC |
7795 SD_SHARE_CPUPOWER |
7796 SD_SHARE_PKG_RESOURCES);
7797 if (nr_node_ids == 1)
7798 pflags &= ~SD_SERIALIZE;
7799 }
7800 if (~cflags & pflags)
7801 return 0;
7802
7803 return 1;
7804 }
7805
7806 static void free_rootdomain(struct root_domain *rd)
7807 {
7808 cpupri_cleanup(&rd->cpupri);
7809
7810 free_cpumask_var(rd->rto_mask);
7811 free_cpumask_var(rd->online);
7812 free_cpumask_var(rd->span);
7813 kfree(rd);
7814 }
7815
7816 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
7817 {
7818 struct root_domain *old_rd = NULL;
7819 unsigned long flags;
7820
7821 spin_lock_irqsave(&rq->lock, flags);
7822
7823 if (rq->rd) {
7824 old_rd = rq->rd;
7825
7826 if (cpumask_test_cpu(rq->cpu, old_rd->online))
7827 set_rq_offline(rq);
7828
7829 cpumask_clear_cpu(rq->cpu, old_rd->span);
7830
7831 /*
7832 * If we dont want to free the old_rt yet then
7833 * set old_rd to NULL to skip the freeing later
7834 * in this function:
7835 */
7836 if (!atomic_dec_and_test(&old_rd->refcount))
7837 old_rd = NULL;
7838 }
7839
7840 atomic_inc(&rd->refcount);
7841 rq->rd = rd;
7842
7843 cpumask_set_cpu(rq->cpu, rd->span);
7844 if (cpumask_test_cpu(rq->cpu, cpu_online_mask))
7845 set_rq_online(rq);
7846
7847 spin_unlock_irqrestore(&rq->lock, flags);
7848
7849 if (old_rd)
7850 free_rootdomain(old_rd);
7851 }
7852
7853 static int init_rootdomain(struct root_domain *rd, bool bootmem)
7854 {
7855 gfp_t gfp = GFP_KERNEL;
7856
7857 memset(rd, 0, sizeof(*rd));
7858
7859 if (bootmem)
7860 gfp = GFP_NOWAIT;
7861
7862 if (!alloc_cpumask_var(&rd->span, gfp))
7863 goto out;
7864 if (!alloc_cpumask_var(&rd->online, gfp))
7865 goto free_span;
7866 if (!alloc_cpumask_var(&rd->rto_mask, gfp))
7867 goto free_online;
7868
7869 if (cpupri_init(&rd->cpupri, bootmem) != 0)
7870 goto free_rto_mask;
7871 return 0;
7872
7873 free_rto_mask:
7874 free_cpumask_var(rd->rto_mask);
7875 free_online:
7876 free_cpumask_var(rd->online);
7877 free_span:
7878 free_cpumask_var(rd->span);
7879 out:
7880 return -ENOMEM;
7881 }
7882
7883 static void init_defrootdomain(void)
7884 {
7885 init_rootdomain(&def_root_domain, true);
7886
7887 atomic_set(&def_root_domain.refcount, 1);
7888 }
7889
7890 static struct root_domain *alloc_rootdomain(void)
7891 {
7892 struct root_domain *rd;
7893
7894 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
7895 if (!rd)
7896 return NULL;
7897
7898 if (init_rootdomain(rd, false) != 0) {
7899 kfree(rd);
7900 return NULL;
7901 }
7902
7903 return rd;
7904 }
7905
7906 /*
7907 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
7908 * hold the hotplug lock.
7909 */
7910 static void
7911 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
7912 {
7913 struct rq *rq = cpu_rq(cpu);
7914 struct sched_domain *tmp;
7915
7916 /* Remove the sched domains which do not contribute to scheduling. */
7917 for (tmp = sd; tmp; ) {
7918 struct sched_domain *parent = tmp->parent;
7919 if (!parent)
7920 break;
7921
7922 if (sd_parent_degenerate(tmp, parent)) {
7923 tmp->parent = parent->parent;
7924 if (parent->parent)
7925 parent->parent->child = tmp;
7926 } else
7927 tmp = tmp->parent;
7928 }
7929
7930 if (sd && sd_degenerate(sd)) {
7931 sd = sd->parent;
7932 if (sd)
7933 sd->child = NULL;
7934 }
7935
7936 sched_domain_debug(sd, cpu);
7937
7938 rq_attach_root(rq, rd);
7939 rcu_assign_pointer(rq->sd, sd);
7940 }
7941
7942 /* cpus with isolated domains */
7943 static cpumask_var_t cpu_isolated_map;
7944
7945 /* Setup the mask of cpus configured for isolated domains */
7946 static int __init isolated_cpu_setup(char *str)
7947 {
7948 cpulist_parse(str, cpu_isolated_map);
7949 return 1;
7950 }
7951
7952 __setup("isolcpus=", isolated_cpu_setup);
7953
7954 /*
7955 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
7956 * to a function which identifies what group(along with sched group) a CPU
7957 * belongs to. The return value of group_fn must be a >= 0 and < nr_cpu_ids
7958 * (due to the fact that we keep track of groups covered with a struct cpumask).
7959 *
7960 * init_sched_build_groups will build a circular linked list of the groups
7961 * covered by the given span, and will set each group's ->cpumask correctly,
7962 * and ->cpu_power to 0.
7963 */
7964 static void
7965 init_sched_build_groups(const struct cpumask *span,
7966 const struct cpumask *cpu_map,
7967 int (*group_fn)(int cpu, const struct cpumask *cpu_map,
7968 struct sched_group **sg,
7969 struct cpumask *tmpmask),
7970 struct cpumask *covered, struct cpumask *tmpmask)
7971 {
7972 struct sched_group *first = NULL, *last = NULL;
7973 int i;
7974
7975 cpumask_clear(covered);
7976
7977 for_each_cpu(i, span) {
7978 struct sched_group *sg;
7979 int group = group_fn(i, cpu_map, &sg, tmpmask);
7980 int j;
7981
7982 if (cpumask_test_cpu(i, covered))
7983 continue;
7984
7985 cpumask_clear(sched_group_cpus(sg));
7986 sg->__cpu_power = 0;
7987
7988 for_each_cpu(j, span) {
7989 if (group_fn(j, cpu_map, NULL, tmpmask) != group)
7990 continue;
7991
7992 cpumask_set_cpu(j, covered);
7993 cpumask_set_cpu(j, sched_group_cpus(sg));
7994 }
7995 if (!first)
7996 first = sg;
7997 if (last)
7998 last->next = sg;
7999 last = sg;
8000 }
8001 last->next = first;
8002 }
8003
8004 #define SD_NODES_PER_DOMAIN 16
8005
8006 #ifdef CONFIG_NUMA
8007
8008 /**
8009 * find_next_best_node - find the next node to include in a sched_domain
8010 * @node: node whose sched_domain we're building
8011 * @used_nodes: nodes already in the sched_domain
8012 *
8013 * Find the next node to include in a given scheduling domain. Simply
8014 * finds the closest node not already in the @used_nodes map.
8015 *
8016 * Should use nodemask_t.
8017 */
8018 static int find_next_best_node(int node, nodemask_t *used_nodes)
8019 {
8020 int i, n, val, min_val, best_node = 0;
8021
8022 min_val = INT_MAX;
8023
8024 for (i = 0; i < nr_node_ids; i++) {
8025 /* Start at @node */
8026 n = (node + i) % nr_node_ids;
8027
8028 if (!nr_cpus_node(n))
8029 continue;
8030
8031 /* Skip already used nodes */
8032 if (node_isset(n, *used_nodes))
8033 continue;
8034
8035 /* Simple min distance search */
8036 val = node_distance(node, n);
8037
8038 if (val < min_val) {
8039 min_val = val;
8040 best_node = n;
8041 }
8042 }
8043
8044 node_set(best_node, *used_nodes);
8045 return best_node;
8046 }
8047
8048 /**
8049 * sched_domain_node_span - get a cpumask for a node's sched_domain
8050 * @node: node whose cpumask we're constructing
8051 * @span: resulting cpumask
8052 *
8053 * Given a node, construct a good cpumask for its sched_domain to span. It
8054 * should be one that prevents unnecessary balancing, but also spreads tasks
8055 * out optimally.
8056 */
8057 static void sched_domain_node_span(int node, struct cpumask *span)
8058 {
8059 nodemask_t used_nodes;
8060 int i;
8061
8062 cpumask_clear(span);
8063 nodes_clear(used_nodes);
8064
8065 cpumask_or(span, span, cpumask_of_node(node));
8066 node_set(node, used_nodes);
8067
8068 for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
8069 int next_node = find_next_best_node(node, &used_nodes);
8070
8071 cpumask_or(span, span, cpumask_of_node(next_node));
8072 }
8073 }
8074 #endif /* CONFIG_NUMA */
8075
8076 int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
8077
8078 /*
8079 * The cpus mask in sched_group and sched_domain hangs off the end.
8080 *
8081 * ( See the the comments in include/linux/sched.h:struct sched_group
8082 * and struct sched_domain. )
8083 */
8084 struct static_sched_group {
8085 struct sched_group sg;
8086 DECLARE_BITMAP(cpus, CONFIG_NR_CPUS);
8087 };
8088
8089 struct static_sched_domain {
8090 struct sched_domain sd;
8091 DECLARE_BITMAP(span, CONFIG_NR_CPUS);
8092 };
8093
8094 struct s_data {
8095 #ifdef CONFIG_NUMA
8096 int sd_allnodes;
8097 cpumask_var_t domainspan;
8098 cpumask_var_t covered;
8099 cpumask_var_t notcovered;
8100 #endif
8101 cpumask_var_t nodemask;
8102 cpumask_var_t this_sibling_map;
8103 cpumask_var_t this_core_map;
8104 cpumask_var_t send_covered;
8105 cpumask_var_t tmpmask;
8106 struct sched_group **sched_group_nodes;
8107 struct root_domain *rd;
8108 };
8109
8110 enum s_alloc {
8111 sa_sched_groups = 0,
8112 sa_rootdomain,
8113 sa_tmpmask,
8114 sa_send_covered,
8115 sa_this_core_map,
8116 sa_this_sibling_map,
8117 sa_nodemask,
8118 sa_sched_group_nodes,
8119 #ifdef CONFIG_NUMA
8120 sa_notcovered,
8121 sa_covered,
8122 sa_domainspan,
8123 #endif
8124 sa_none,
8125 };
8126
8127 /*
8128 * SMT sched-domains:
8129 */
8130 #ifdef CONFIG_SCHED_SMT
8131 static DEFINE_PER_CPU(struct static_sched_domain, cpu_domains);
8132 static DEFINE_PER_CPU(struct static_sched_group, sched_group_cpus);
8133
8134 static int
8135 cpu_to_cpu_group(int cpu, const struct cpumask *cpu_map,
8136 struct sched_group **sg, struct cpumask *unused)
8137 {
8138 if (sg)
8139 *sg = &per_cpu(sched_group_cpus, cpu).sg;
8140 return cpu;
8141 }
8142 #endif /* CONFIG_SCHED_SMT */
8143
8144 /*
8145 * multi-core sched-domains:
8146 */
8147 #ifdef CONFIG_SCHED_MC
8148 static DEFINE_PER_CPU(struct static_sched_domain, core_domains);
8149 static DEFINE_PER_CPU(struct static_sched_group, sched_group_core);
8150 #endif /* CONFIG_SCHED_MC */
8151
8152 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
8153 static int
8154 cpu_to_core_group(int cpu, const struct cpumask *cpu_map,
8155 struct sched_group **sg, struct cpumask *mask)
8156 {
8157 int group;
8158
8159 cpumask_and(mask, topology_thread_cpumask(cpu), cpu_map);
8160 group = cpumask_first(mask);
8161 if (sg)
8162 *sg = &per_cpu(sched_group_core, group).sg;
8163 return group;
8164 }
8165 #elif defined(CONFIG_SCHED_MC)
8166 static int
8167 cpu_to_core_group(int cpu, const struct cpumask *cpu_map,
8168 struct sched_group **sg, struct cpumask *unused)
8169 {
8170 if (sg)
8171 *sg = &per_cpu(sched_group_core, cpu).sg;
8172 return cpu;
8173 }
8174 #endif
8175
8176 static DEFINE_PER_CPU(struct static_sched_domain, phys_domains);
8177 static DEFINE_PER_CPU(struct static_sched_group, sched_group_phys);
8178
8179 static int
8180 cpu_to_phys_group(int cpu, const struct cpumask *cpu_map,
8181 struct sched_group **sg, struct cpumask *mask)
8182 {
8183 int group;
8184 #ifdef CONFIG_SCHED_MC
8185 cpumask_and(mask, cpu_coregroup_mask(cpu), cpu_map);
8186 group = cpumask_first(mask);
8187 #elif defined(CONFIG_SCHED_SMT)
8188 cpumask_and(mask, topology_thread_cpumask(cpu), cpu_map);
8189 group = cpumask_first(mask);
8190 #else
8191 group = cpu;
8192 #endif
8193 if (sg)
8194 *sg = &per_cpu(sched_group_phys, group).sg;
8195 return group;
8196 }
8197
8198 #ifdef CONFIG_NUMA
8199 /*
8200 * The init_sched_build_groups can't handle what we want to do with node
8201 * groups, so roll our own. Now each node has its own list of groups which
8202 * gets dynamically allocated.
8203 */
8204 static DEFINE_PER_CPU(struct static_sched_domain, node_domains);
8205 static struct sched_group ***sched_group_nodes_bycpu;
8206
8207 static DEFINE_PER_CPU(struct static_sched_domain, allnodes_domains);
8208 static DEFINE_PER_CPU(struct static_sched_group, sched_group_allnodes);
8209
8210 static int cpu_to_allnodes_group(int cpu, const struct cpumask *cpu_map,
8211 struct sched_group **sg,
8212 struct cpumask *nodemask)
8213 {
8214 int group;
8215
8216 cpumask_and(nodemask, cpumask_of_node(cpu_to_node(cpu)), cpu_map);
8217 group = cpumask_first(nodemask);
8218
8219 if (sg)
8220 *sg = &per_cpu(sched_group_allnodes, group).sg;
8221 return group;
8222 }
8223
8224 static void init_numa_sched_groups_power(struct sched_group *group_head)
8225 {
8226 struct sched_group *sg = group_head;
8227 int j;
8228
8229 if (!sg)
8230 return;
8231 do {
8232 for_each_cpu(j, sched_group_cpus(sg)) {
8233 struct sched_domain *sd;
8234
8235 sd = &per_cpu(phys_domains, j).sd;
8236 if (j != group_first_cpu(sd->groups)) {
8237 /*
8238 * Only add "power" once for each
8239 * physical package.
8240 */
8241 continue;
8242 }
8243
8244 sg_inc_cpu_power(sg, sd->groups->__cpu_power);
8245 }
8246 sg = sg->next;
8247 } while (sg != group_head);
8248 }
8249 #endif /* CONFIG_NUMA */
8250
8251 #ifdef CONFIG_NUMA
8252 /* Free memory allocated for various sched_group structures */
8253 static void free_sched_groups(const struct cpumask *cpu_map,
8254 struct cpumask *nodemask)
8255 {
8256 int cpu, i;
8257
8258 for_each_cpu(cpu, cpu_map) {
8259 struct sched_group **sched_group_nodes
8260 = sched_group_nodes_bycpu[cpu];
8261
8262 if (!sched_group_nodes)
8263 continue;
8264
8265 for (i = 0; i < nr_node_ids; i++) {
8266 struct sched_group *oldsg, *sg = sched_group_nodes[i];
8267
8268 cpumask_and(nodemask, cpumask_of_node(i), cpu_map);
8269 if (cpumask_empty(nodemask))
8270 continue;
8271
8272 if (sg == NULL)
8273 continue;
8274 sg = sg->next;
8275 next_sg:
8276 oldsg = sg;
8277 sg = sg->next;
8278 kfree(oldsg);
8279 if (oldsg != sched_group_nodes[i])
8280 goto next_sg;
8281 }
8282 kfree(sched_group_nodes);
8283 sched_group_nodes_bycpu[cpu] = NULL;
8284 }
8285 }
8286 #else /* !CONFIG_NUMA */
8287 static void free_sched_groups(const struct cpumask *cpu_map,
8288 struct cpumask *nodemask)
8289 {
8290 }
8291 #endif /* CONFIG_NUMA */
8292
8293 /*
8294 * Initialize sched groups cpu_power.
8295 *
8296 * cpu_power indicates the capacity of sched group, which is used while
8297 * distributing the load between different sched groups in a sched domain.
8298 * Typically cpu_power for all the groups in a sched domain will be same unless
8299 * there are asymmetries in the topology. If there are asymmetries, group
8300 * having more cpu_power will pickup more load compared to the group having
8301 * less cpu_power.
8302 *
8303 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
8304 * the maximum number of tasks a group can handle in the presence of other idle
8305 * or lightly loaded groups in the same sched domain.
8306 */
8307 static void init_sched_groups_power(int cpu, struct sched_domain *sd)
8308 {
8309 struct sched_domain *child;
8310 struct sched_group *group;
8311
8312 WARN_ON(!sd || !sd->groups);
8313
8314 if (cpu != group_first_cpu(sd->groups))
8315 return;
8316
8317 child = sd->child;
8318
8319 sd->groups->__cpu_power = 0;
8320
8321 /*
8322 * For perf policy, if the groups in child domain share resources
8323 * (for example cores sharing some portions of the cache hierarchy
8324 * or SMT), then set this domain groups cpu_power such that each group
8325 * can handle only one task, when there are other idle groups in the
8326 * same sched domain.
8327 */
8328 if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) &&
8329 (child->flags &
8330 (SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) {
8331 sg_inc_cpu_power(sd->groups, SCHED_LOAD_SCALE);
8332 return;
8333 }
8334
8335 /*
8336 * add cpu_power of each child group to this groups cpu_power
8337 */
8338 group = child->groups;
8339 do {
8340 sg_inc_cpu_power(sd->groups, group->__cpu_power);
8341 group = group->next;
8342 } while (group != child->groups);
8343 }
8344
8345 /*
8346 * Initializers for schedule domains
8347 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
8348 */
8349
8350 #ifdef CONFIG_SCHED_DEBUG
8351 # define SD_INIT_NAME(sd, type) sd->name = #type
8352 #else
8353 # define SD_INIT_NAME(sd, type) do { } while (0)
8354 #endif
8355
8356 #define SD_INIT(sd, type) sd_init_##type(sd)
8357
8358 #define SD_INIT_FUNC(type) \
8359 static noinline void sd_init_##type(struct sched_domain *sd) \
8360 { \
8361 memset(sd, 0, sizeof(*sd)); \
8362 *sd = SD_##type##_INIT; \
8363 sd->level = SD_LV_##type; \
8364 SD_INIT_NAME(sd, type); \
8365 }
8366
8367 SD_INIT_FUNC(CPU)
8368 #ifdef CONFIG_NUMA
8369 SD_INIT_FUNC(ALLNODES)
8370 SD_INIT_FUNC(NODE)
8371 #endif
8372 #ifdef CONFIG_SCHED_SMT
8373 SD_INIT_FUNC(SIBLING)
8374 #endif
8375 #ifdef CONFIG_SCHED_MC
8376 SD_INIT_FUNC(MC)
8377 #endif
8378
8379 static int default_relax_domain_level = -1;
8380
8381 static int __init setup_relax_domain_level(char *str)
8382 {
8383 unsigned long val;
8384
8385 val = simple_strtoul(str, NULL, 0);
8386 if (val < SD_LV_MAX)
8387 default_relax_domain_level = val;
8388
8389 return 1;
8390 }
8391 __setup("relax_domain_level=", setup_relax_domain_level);
8392
8393 static void set_domain_attribute(struct sched_domain *sd,
8394 struct sched_domain_attr *attr)
8395 {
8396 int request;
8397
8398 if (!attr || attr->relax_domain_level < 0) {
8399 if (default_relax_domain_level < 0)
8400 return;
8401 else
8402 request = default_relax_domain_level;
8403 } else
8404 request = attr->relax_domain_level;
8405 if (request < sd->level) {
8406 /* turn off idle balance on this domain */
8407 sd->flags &= ~(SD_WAKE_IDLE|SD_BALANCE_NEWIDLE);
8408 } else {
8409 /* turn on idle balance on this domain */
8410 sd->flags |= (SD_WAKE_IDLE_FAR|SD_BALANCE_NEWIDLE);
8411 }
8412 }
8413
8414 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
8415 const struct cpumask *cpu_map)
8416 {
8417 switch (what) {
8418 case sa_sched_groups:
8419 free_sched_groups(cpu_map, d->tmpmask); /* fall through */
8420 d->sched_group_nodes = NULL;
8421 case sa_rootdomain:
8422 free_rootdomain(d->rd); /* fall through */
8423 case sa_tmpmask:
8424 free_cpumask_var(d->tmpmask); /* fall through */
8425 case sa_send_covered:
8426 free_cpumask_var(d->send_covered); /* fall through */
8427 case sa_this_core_map:
8428 free_cpumask_var(d->this_core_map); /* fall through */
8429 case sa_this_sibling_map:
8430 free_cpumask_var(d->this_sibling_map); /* fall through */
8431 case sa_nodemask:
8432 free_cpumask_var(d->nodemask); /* fall through */
8433 case sa_sched_group_nodes:
8434 #ifdef CONFIG_NUMA
8435 kfree(d->sched_group_nodes); /* fall through */
8436 case sa_notcovered:
8437 free_cpumask_var(d->notcovered); /* fall through */
8438 case sa_covered:
8439 free_cpumask_var(d->covered); /* fall through */
8440 case sa_domainspan:
8441 free_cpumask_var(d->domainspan); /* fall through */
8442 #endif
8443 case sa_none:
8444 break;
8445 }
8446 }
8447
8448 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
8449 const struct cpumask *cpu_map)
8450 {
8451 #ifdef CONFIG_NUMA
8452 if (!alloc_cpumask_var(&d->domainspan, GFP_KERNEL))
8453 return sa_none;
8454 if (!alloc_cpumask_var(&d->covered, GFP_KERNEL))
8455 return sa_domainspan;
8456 if (!alloc_cpumask_var(&d->notcovered, GFP_KERNEL))
8457 return sa_covered;
8458 /* Allocate the per-node list of sched groups */
8459 d->sched_group_nodes = kcalloc(nr_node_ids,
8460 sizeof(struct sched_group *), GFP_KERNEL);
8461 if (!d->sched_group_nodes) {
8462 printk(KERN_WARNING "Can not alloc sched group node list\n");
8463 return sa_notcovered;
8464 }
8465 sched_group_nodes_bycpu[cpumask_first(cpu_map)] = d->sched_group_nodes;
8466 #endif
8467 if (!alloc_cpumask_var(&d->nodemask, GFP_KERNEL))
8468 return sa_sched_group_nodes;
8469 if (!alloc_cpumask_var(&d->this_sibling_map, GFP_KERNEL))
8470 return sa_nodemask;
8471 if (!alloc_cpumask_var(&d->this_core_map, GFP_KERNEL))
8472 return sa_this_sibling_map;
8473 if (!alloc_cpumask_var(&d->send_covered, GFP_KERNEL))
8474 return sa_this_core_map;
8475 if (!alloc_cpumask_var(&d->tmpmask, GFP_KERNEL))
8476 return sa_send_covered;
8477 d->rd = alloc_rootdomain();
8478 if (!d->rd) {
8479 printk(KERN_WARNING "Cannot alloc root domain\n");
8480 return sa_tmpmask;
8481 }
8482 return sa_rootdomain;
8483 }
8484
8485 static struct sched_domain *__build_numa_sched_domains(struct s_data *d,
8486 const struct cpumask *cpu_map, struct sched_domain_attr *attr, int i)
8487 {
8488 struct sched_domain *sd = NULL;
8489 #ifdef CONFIG_NUMA
8490 struct sched_domain *parent;
8491
8492 d->sd_allnodes = 0;
8493 if (cpumask_weight(cpu_map) >
8494 SD_NODES_PER_DOMAIN * cpumask_weight(d->nodemask)) {
8495 sd = &per_cpu(allnodes_domains, i).sd;
8496 SD_INIT(sd, ALLNODES);
8497 set_domain_attribute(sd, attr);
8498 cpumask_copy(sched_domain_span(sd), cpu_map);
8499 cpu_to_allnodes_group(i, cpu_map, &sd->groups, d->tmpmask);
8500 d->sd_allnodes = 1;
8501 }
8502 parent = sd;
8503
8504 sd = &per_cpu(node_domains, i).sd;
8505 SD_INIT(sd, NODE);
8506 set_domain_attribute(sd, attr);
8507 sched_domain_node_span(cpu_to_node(i), sched_domain_span(sd));
8508 sd->parent = parent;
8509 if (parent)
8510 parent->child = sd;
8511 cpumask_and(sched_domain_span(sd), sched_domain_span(sd), cpu_map);
8512 #endif
8513 return sd;
8514 }
8515
8516 static struct sched_domain *__build_cpu_sched_domain(struct s_data *d,
8517 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
8518 struct sched_domain *parent, int i)
8519 {
8520 struct sched_domain *sd;
8521 sd = &per_cpu(phys_domains, i).sd;
8522 SD_INIT(sd, CPU);
8523 set_domain_attribute(sd, attr);
8524 cpumask_copy(sched_domain_span(sd), d->nodemask);
8525 sd->parent = parent;
8526 if (parent)
8527 parent->child = sd;
8528 cpu_to_phys_group(i, cpu_map, &sd->groups, d->tmpmask);
8529 return sd;
8530 }
8531
8532 static struct sched_domain *__build_mc_sched_domain(struct s_data *d,
8533 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
8534 struct sched_domain *parent, int i)
8535 {
8536 struct sched_domain *sd = parent;
8537 #ifdef CONFIG_SCHED_MC
8538 sd = &per_cpu(core_domains, i).sd;
8539 SD_INIT(sd, MC);
8540 set_domain_attribute(sd, attr);
8541 cpumask_and(sched_domain_span(sd), cpu_map, cpu_coregroup_mask(i));
8542 sd->parent = parent;
8543 parent->child = sd;
8544 cpu_to_core_group(i, cpu_map, &sd->groups, d->tmpmask);
8545 #endif
8546 return sd;
8547 }
8548
8549 static struct sched_domain *__build_smt_sched_domain(struct s_data *d,
8550 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
8551 struct sched_domain *parent, int i)
8552 {
8553 struct sched_domain *sd = parent;
8554 #ifdef CONFIG_SCHED_SMT
8555 sd = &per_cpu(cpu_domains, i).sd;
8556 SD_INIT(sd, SIBLING);
8557 set_domain_attribute(sd, attr);
8558 cpumask_and(sched_domain_span(sd), cpu_map, topology_thread_cpumask(i));
8559 sd->parent = parent;
8560 parent->child = sd;
8561 cpu_to_cpu_group(i, cpu_map, &sd->groups, d->tmpmask);
8562 #endif
8563 return sd;
8564 }
8565
8566 static void build_sched_groups(struct s_data *d, enum sched_domain_level l,
8567 const struct cpumask *cpu_map, int cpu)
8568 {
8569 switch (l) {
8570 #ifdef CONFIG_SCHED_SMT
8571 case SD_LV_SIBLING: /* set up CPU (sibling) groups */
8572 cpumask_and(d->this_sibling_map, cpu_map,
8573 topology_thread_cpumask(cpu));
8574 if (cpu == cpumask_first(d->this_sibling_map))
8575 init_sched_build_groups(d->this_sibling_map, cpu_map,
8576 &cpu_to_cpu_group,
8577 d->send_covered, d->tmpmask);
8578 break;
8579 #endif
8580 #ifdef CONFIG_SCHED_MC
8581 case SD_LV_MC: /* set up multi-core groups */
8582 cpumask_and(d->this_core_map, cpu_map, cpu_coregroup_mask(cpu));
8583 if (cpu == cpumask_first(d->this_core_map))
8584 init_sched_build_groups(d->this_core_map, cpu_map,
8585 &cpu_to_core_group,
8586 d->send_covered, d->tmpmask);
8587 break;
8588 #endif
8589 case SD_LV_CPU: /* set up physical groups */
8590 cpumask_and(d->nodemask, cpumask_of_node(cpu), cpu_map);
8591 if (!cpumask_empty(d->nodemask))
8592 init_sched_build_groups(d->nodemask, cpu_map,
8593 &cpu_to_phys_group,
8594 d->send_covered, d->tmpmask);
8595 break;
8596 #ifdef CONFIG_NUMA
8597 case SD_LV_ALLNODES:
8598 init_sched_build_groups(cpu_map, cpu_map, &cpu_to_allnodes_group,
8599 d->send_covered, d->tmpmask);
8600 break;
8601 #endif
8602 default:
8603 break;
8604 }
8605 }
8606
8607 /*
8608 * Build sched domains for a given set of cpus and attach the sched domains
8609 * to the individual cpus
8610 */
8611 static int __build_sched_domains(const struct cpumask *cpu_map,
8612 struct sched_domain_attr *attr)
8613 {
8614 enum s_alloc alloc_state = sa_none;
8615 struct s_data d;
8616 int i;
8617 #ifdef CONFIG_NUMA
8618 d.sd_allnodes = 0;
8619 #endif
8620
8621 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
8622 if (alloc_state != sa_rootdomain)
8623 goto error;
8624 alloc_state = sa_sched_groups;
8625
8626 /*
8627 * Set up domains for cpus specified by the cpu_map.
8628 */
8629 for_each_cpu(i, cpu_map) {
8630 struct sched_domain *sd;
8631
8632 cpumask_and(d.nodemask, cpumask_of_node(cpu_to_node(i)),
8633 cpu_map);
8634
8635 sd = __build_numa_sched_domains(&d, cpu_map, attr, i);
8636 sd = __build_cpu_sched_domain(&d, cpu_map, attr, sd, i);
8637 sd = __build_mc_sched_domain(&d, cpu_map, attr, sd, i);
8638 sd = __build_smt_sched_domain(&d, cpu_map, attr, sd, i);
8639 }
8640
8641 for_each_cpu(i, cpu_map) {
8642 build_sched_groups(&d, SD_LV_SIBLING, cpu_map, i);
8643 build_sched_groups(&d, SD_LV_MC, cpu_map, i);
8644 }
8645
8646 /* Set up physical groups */
8647 for (i = 0; i < nr_node_ids; i++)
8648 build_sched_groups(&d, SD_LV_CPU, cpu_map, i);
8649
8650 #ifdef CONFIG_NUMA
8651 /* Set up node groups */
8652 if (d.sd_allnodes)
8653 build_sched_groups(&d, SD_LV_ALLNODES, cpu_map, 0);
8654
8655 for (i = 0; i < nr_node_ids; i++) {
8656 /* Set up node groups */
8657 struct sched_group *sg, *prev;
8658 int j;
8659
8660 cpumask_clear(d.covered);
8661 cpumask_and(d.nodemask, cpumask_of_node(i), cpu_map);
8662 if (cpumask_empty(d.nodemask)) {
8663 d.sched_group_nodes[i] = NULL;
8664 continue;
8665 }
8666
8667 sched_domain_node_span(i, d.domainspan);
8668 cpumask_and(d.domainspan, d.domainspan, cpu_map);
8669
8670 sg = kmalloc_node(sizeof(struct sched_group) + cpumask_size(),
8671 GFP_KERNEL, i);
8672 if (!sg) {
8673 printk(KERN_WARNING "Can not alloc domain group for "
8674 "node %d\n", i);
8675 goto error;
8676 }
8677 d.sched_group_nodes[i] = sg;
8678 for_each_cpu(j, d.nodemask) {
8679 struct sched_domain *sd;
8680
8681 sd = &per_cpu(node_domains, j).sd;
8682 sd->groups = sg;
8683 }
8684 sg->__cpu_power = 0;
8685 cpumask_copy(sched_group_cpus(sg), d.nodemask);
8686 sg->next = sg;
8687 cpumask_or(d.covered, d.covered, d.nodemask);
8688 prev = sg;
8689
8690 for (j = 0; j < nr_node_ids; j++) {
8691 int n = (i + j) % nr_node_ids;
8692
8693 cpumask_complement(d.notcovered, d.covered);
8694 cpumask_and(d.tmpmask, d.notcovered, cpu_map);
8695 cpumask_and(d.tmpmask, d.tmpmask, d.domainspan);
8696 if (cpumask_empty(d.tmpmask))
8697 break;
8698
8699 cpumask_and(d.tmpmask, d.tmpmask, cpumask_of_node(n));
8700 if (cpumask_empty(d.tmpmask))
8701 continue;
8702
8703 sg = kmalloc_node(sizeof(struct sched_group) +
8704 cpumask_size(),
8705 GFP_KERNEL, i);
8706 if (!sg) {
8707 printk(KERN_WARNING
8708 "Can not alloc domain group for node %d\n", j);
8709 goto error;
8710 }
8711 sg->__cpu_power = 0;
8712 cpumask_copy(sched_group_cpus(sg), d.tmpmask);
8713 sg->next = prev->next;
8714 cpumask_or(d.covered, d.covered, d.tmpmask);
8715 prev->next = sg;
8716 prev = sg;
8717 }
8718 }
8719 #endif
8720
8721 /* Calculate CPU power for physical packages and nodes */
8722 #ifdef CONFIG_SCHED_SMT
8723 for_each_cpu(i, cpu_map) {
8724 struct sched_domain *sd = &per_cpu(cpu_domains, i).sd;
8725
8726 init_sched_groups_power(i, sd);
8727 }
8728 #endif
8729 #ifdef CONFIG_SCHED_MC
8730 for_each_cpu(i, cpu_map) {
8731 struct sched_domain *sd = &per_cpu(core_domains, i).sd;
8732
8733 init_sched_groups_power(i, sd);
8734 }
8735 #endif
8736
8737 for_each_cpu(i, cpu_map) {
8738 struct sched_domain *sd = &per_cpu(phys_domains, i).sd;
8739
8740 init_sched_groups_power(i, sd);
8741 }
8742
8743 #ifdef CONFIG_NUMA
8744 for (i = 0; i < nr_node_ids; i++)
8745 init_numa_sched_groups_power(d.sched_group_nodes[i]);
8746
8747 if (d.sd_allnodes) {
8748 struct sched_group *sg;
8749
8750 cpu_to_allnodes_group(cpumask_first(cpu_map), cpu_map, &sg,
8751 d.tmpmask);
8752 init_numa_sched_groups_power(sg);
8753 }
8754 #endif
8755
8756 /* Attach the domains */
8757 for_each_cpu(i, cpu_map) {
8758 struct sched_domain *sd;
8759 #ifdef CONFIG_SCHED_SMT
8760 sd = &per_cpu(cpu_domains, i).sd;
8761 #elif defined(CONFIG_SCHED_MC)
8762 sd = &per_cpu(core_domains, i).sd;
8763 #else
8764 sd = &per_cpu(phys_domains, i).sd;
8765 #endif
8766 cpu_attach_domain(sd, d.rd, i);
8767 }
8768
8769 d.sched_group_nodes = NULL; /* don't free this we still need it */
8770 __free_domain_allocs(&d, sa_tmpmask, cpu_map);
8771 return 0;
8772
8773 error:
8774 __free_domain_allocs(&d, alloc_state, cpu_map);
8775 return -ENOMEM;
8776 }
8777
8778 static int build_sched_domains(const struct cpumask *cpu_map)
8779 {
8780 return __build_sched_domains(cpu_map, NULL);
8781 }
8782
8783 static struct cpumask *doms_cur; /* current sched domains */
8784 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
8785 static struct sched_domain_attr *dattr_cur;
8786 /* attribues of custom domains in 'doms_cur' */
8787
8788 /*
8789 * Special case: If a kmalloc of a doms_cur partition (array of
8790 * cpumask) fails, then fallback to a single sched domain,
8791 * as determined by the single cpumask fallback_doms.
8792 */
8793 static cpumask_var_t fallback_doms;
8794
8795 /*
8796 * arch_update_cpu_topology lets virtualized architectures update the
8797 * cpu core maps. It is supposed to return 1 if the topology changed
8798 * or 0 if it stayed the same.
8799 */
8800 int __attribute__((weak)) arch_update_cpu_topology(void)
8801 {
8802 return 0;
8803 }
8804
8805 /*
8806 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
8807 * For now this just excludes isolated cpus, but could be used to
8808 * exclude other special cases in the future.
8809 */
8810 static int arch_init_sched_domains(const struct cpumask *cpu_map)
8811 {
8812 int err;
8813
8814 arch_update_cpu_topology();
8815 ndoms_cur = 1;
8816 doms_cur = kmalloc(cpumask_size(), GFP_KERNEL);
8817 if (!doms_cur)
8818 doms_cur = fallback_doms;
8819 cpumask_andnot(doms_cur, cpu_map, cpu_isolated_map);
8820 dattr_cur = NULL;
8821 err = build_sched_domains(doms_cur);
8822 register_sched_domain_sysctl();
8823
8824 return err;
8825 }
8826
8827 static void arch_destroy_sched_domains(const struct cpumask *cpu_map,
8828 struct cpumask *tmpmask)
8829 {
8830 free_sched_groups(cpu_map, tmpmask);
8831 }
8832
8833 /*
8834 * Detach sched domains from a group of cpus specified in cpu_map
8835 * These cpus will now be attached to the NULL domain
8836 */
8837 static void detach_destroy_domains(const struct cpumask *cpu_map)
8838 {
8839 /* Save because hotplug lock held. */
8840 static DECLARE_BITMAP(tmpmask, CONFIG_NR_CPUS);
8841 int i;
8842
8843 for_each_cpu(i, cpu_map)
8844 cpu_attach_domain(NULL, &def_root_domain, i);
8845 synchronize_sched();
8846 arch_destroy_sched_domains(cpu_map, to_cpumask(tmpmask));
8847 }
8848
8849 /* handle null as "default" */
8850 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
8851 struct sched_domain_attr *new, int idx_new)
8852 {
8853 struct sched_domain_attr tmp;
8854
8855 /* fast path */
8856 if (!new && !cur)
8857 return 1;
8858
8859 tmp = SD_ATTR_INIT;
8860 return !memcmp(cur ? (cur + idx_cur) : &tmp,
8861 new ? (new + idx_new) : &tmp,
8862 sizeof(struct sched_domain_attr));
8863 }
8864
8865 /*
8866 * Partition sched domains as specified by the 'ndoms_new'
8867 * cpumasks in the array doms_new[] of cpumasks. This compares
8868 * doms_new[] to the current sched domain partitioning, doms_cur[].
8869 * It destroys each deleted domain and builds each new domain.
8870 *
8871 * 'doms_new' is an array of cpumask's of length 'ndoms_new'.
8872 * The masks don't intersect (don't overlap.) We should setup one
8873 * sched domain for each mask. CPUs not in any of the cpumasks will
8874 * not be load balanced. If the same cpumask appears both in the
8875 * current 'doms_cur' domains and in the new 'doms_new', we can leave
8876 * it as it is.
8877 *
8878 * The passed in 'doms_new' should be kmalloc'd. This routine takes
8879 * ownership of it and will kfree it when done with it. If the caller
8880 * failed the kmalloc call, then it can pass in doms_new == NULL &&
8881 * ndoms_new == 1, and partition_sched_domains() will fallback to
8882 * the single partition 'fallback_doms', it also forces the domains
8883 * to be rebuilt.
8884 *
8885 * If doms_new == NULL it will be replaced with cpu_online_mask.
8886 * ndoms_new == 0 is a special case for destroying existing domains,
8887 * and it will not create the default domain.
8888 *
8889 * Call with hotplug lock held
8890 */
8891 /* FIXME: Change to struct cpumask *doms_new[] */
8892 void partition_sched_domains(int ndoms_new, struct cpumask *doms_new,
8893 struct sched_domain_attr *dattr_new)
8894 {
8895 int i, j, n;
8896 int new_topology;
8897
8898 mutex_lock(&sched_domains_mutex);
8899
8900 /* always unregister in case we don't destroy any domains */
8901 unregister_sched_domain_sysctl();
8902
8903 /* Let architecture update cpu core mappings. */
8904 new_topology = arch_update_cpu_topology();
8905
8906 n = doms_new ? ndoms_new : 0;
8907
8908 /* Destroy deleted domains */
8909 for (i = 0; i < ndoms_cur; i++) {
8910 for (j = 0; j < n && !new_topology; j++) {
8911 if (cpumask_equal(&doms_cur[i], &doms_new[j])
8912 && dattrs_equal(dattr_cur, i, dattr_new, j))
8913 goto match1;
8914 }
8915 /* no match - a current sched domain not in new doms_new[] */
8916 detach_destroy_domains(doms_cur + i);
8917 match1:
8918 ;
8919 }
8920
8921 if (doms_new == NULL) {
8922 ndoms_cur = 0;
8923 doms_new = fallback_doms;
8924 cpumask_andnot(&doms_new[0], cpu_online_mask, cpu_isolated_map);
8925 WARN_ON_ONCE(dattr_new);
8926 }
8927
8928 /* Build new domains */
8929 for (i = 0; i < ndoms_new; i++) {
8930 for (j = 0; j < ndoms_cur && !new_topology; j++) {
8931 if (cpumask_equal(&doms_new[i], &doms_cur[j])
8932 && dattrs_equal(dattr_new, i, dattr_cur, j))
8933 goto match2;
8934 }
8935 /* no match - add a new doms_new */
8936 __build_sched_domains(doms_new + i,
8937 dattr_new ? dattr_new + i : NULL);
8938 match2:
8939 ;
8940 }
8941
8942 /* Remember the new sched domains */
8943 if (doms_cur != fallback_doms)
8944 kfree(doms_cur);
8945 kfree(dattr_cur); /* kfree(NULL) is safe */
8946 doms_cur = doms_new;
8947 dattr_cur = dattr_new;
8948 ndoms_cur = ndoms_new;
8949
8950 register_sched_domain_sysctl();
8951
8952 mutex_unlock(&sched_domains_mutex);
8953 }
8954
8955 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
8956 static void arch_reinit_sched_domains(void)
8957 {
8958 get_online_cpus();
8959
8960 /* Destroy domains first to force the rebuild */
8961 partition_sched_domains(0, NULL, NULL);
8962
8963 rebuild_sched_domains();
8964 put_online_cpus();
8965 }
8966
8967 static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
8968 {
8969 unsigned int level = 0;
8970
8971 if (sscanf(buf, "%u", &level) != 1)
8972 return -EINVAL;
8973
8974 /*
8975 * level is always be positive so don't check for
8976 * level < POWERSAVINGS_BALANCE_NONE which is 0
8977 * What happens on 0 or 1 byte write,
8978 * need to check for count as well?
8979 */
8980
8981 if (level >= MAX_POWERSAVINGS_BALANCE_LEVELS)
8982 return -EINVAL;
8983
8984 if (smt)
8985 sched_smt_power_savings = level;
8986 else
8987 sched_mc_power_savings = level;
8988
8989 arch_reinit_sched_domains();
8990
8991 return count;
8992 }
8993
8994 #ifdef CONFIG_SCHED_MC
8995 static ssize_t sched_mc_power_savings_show(struct sysdev_class *class,
8996 char *page)
8997 {
8998 return sprintf(page, "%u\n", sched_mc_power_savings);
8999 }
9000 static ssize_t sched_mc_power_savings_store(struct sysdev_class *class,
9001 const char *buf, size_t count)
9002 {
9003 return sched_power_savings_store(buf, count, 0);
9004 }
9005 static SYSDEV_CLASS_ATTR(sched_mc_power_savings, 0644,
9006 sched_mc_power_savings_show,
9007 sched_mc_power_savings_store);
9008 #endif
9009
9010 #ifdef CONFIG_SCHED_SMT
9011 static ssize_t sched_smt_power_savings_show(struct sysdev_class *dev,
9012 char *page)
9013 {
9014 return sprintf(page, "%u\n", sched_smt_power_savings);
9015 }
9016 static ssize_t sched_smt_power_savings_store(struct sysdev_class *dev,
9017 const char *buf, size_t count)
9018 {
9019 return sched_power_savings_store(buf, count, 1);
9020 }
9021 static SYSDEV_CLASS_ATTR(sched_smt_power_savings, 0644,
9022 sched_smt_power_savings_show,
9023 sched_smt_power_savings_store);
9024 #endif
9025
9026 int __init sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
9027 {
9028 int err = 0;
9029
9030 #ifdef CONFIG_SCHED_SMT
9031 if (smt_capable())
9032 err = sysfs_create_file(&cls->kset.kobj,
9033 &attr_sched_smt_power_savings.attr);
9034 #endif
9035 #ifdef CONFIG_SCHED_MC
9036 if (!err && mc_capable())
9037 err = sysfs_create_file(&cls->kset.kobj,
9038 &attr_sched_mc_power_savings.attr);
9039 #endif
9040 return err;
9041 }
9042 #endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
9043
9044 #ifndef CONFIG_CPUSETS
9045 /*
9046 * Add online and remove offline CPUs from the scheduler domains.
9047 * When cpusets are enabled they take over this function.
9048 */
9049 static int update_sched_domains(struct notifier_block *nfb,
9050 unsigned long action, void *hcpu)
9051 {
9052 switch (action) {
9053 case CPU_ONLINE:
9054 case CPU_ONLINE_FROZEN:
9055 case CPU_DEAD:
9056 case CPU_DEAD_FROZEN:
9057 partition_sched_domains(1, NULL, NULL);
9058 return NOTIFY_OK;
9059
9060 default:
9061 return NOTIFY_DONE;
9062 }
9063 }
9064 #endif
9065
9066 static int update_runtime(struct notifier_block *nfb,
9067 unsigned long action, void *hcpu)
9068 {
9069 int cpu = (int)(long)hcpu;
9070
9071 switch (action) {
9072 case CPU_DOWN_PREPARE:
9073 case CPU_DOWN_PREPARE_FROZEN:
9074 disable_runtime(cpu_rq(cpu));
9075 return NOTIFY_OK;
9076
9077 case CPU_DOWN_FAILED:
9078 case CPU_DOWN_FAILED_FROZEN:
9079 case CPU_ONLINE:
9080 case CPU_ONLINE_FROZEN:
9081 enable_runtime(cpu_rq(cpu));
9082 return NOTIFY_OK;
9083
9084 default:
9085 return NOTIFY_DONE;
9086 }
9087 }
9088
9089 void __init sched_init_smp(void)
9090 {
9091 cpumask_var_t non_isolated_cpus;
9092
9093 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
9094
9095 #if defined(CONFIG_NUMA)
9096 sched_group_nodes_bycpu = kzalloc(nr_cpu_ids * sizeof(void **),
9097 GFP_KERNEL);
9098 BUG_ON(sched_group_nodes_bycpu == NULL);
9099 #endif
9100 get_online_cpus();
9101 mutex_lock(&sched_domains_mutex);
9102 arch_init_sched_domains(cpu_online_mask);
9103 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
9104 if (cpumask_empty(non_isolated_cpus))
9105 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
9106 mutex_unlock(&sched_domains_mutex);
9107 put_online_cpus();
9108
9109 #ifndef CONFIG_CPUSETS
9110 /* XXX: Theoretical race here - CPU may be hotplugged now */
9111 hotcpu_notifier(update_sched_domains, 0);
9112 #endif
9113
9114 /* RT runtime code needs to handle some hotplug events */
9115 hotcpu_notifier(update_runtime, 0);
9116
9117 init_hrtick();
9118
9119 /* Move init over to a non-isolated CPU */
9120 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
9121 BUG();
9122 sched_init_granularity();
9123 free_cpumask_var(non_isolated_cpus);
9124
9125 alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
9126 init_sched_rt_class();
9127 }
9128 #else
9129 void __init sched_init_smp(void)
9130 {
9131 sched_init_granularity();
9132 }
9133 #endif /* CONFIG_SMP */
9134
9135 const_debug unsigned int sysctl_timer_migration = 1;
9136
9137 int in_sched_functions(unsigned long addr)
9138 {
9139 return in_lock_functions(addr) ||
9140 (addr >= (unsigned long)__sched_text_start
9141 && addr < (unsigned long)__sched_text_end);
9142 }
9143
9144 static void init_cfs_rq(struct cfs_rq *cfs_rq, struct rq *rq)
9145 {
9146 cfs_rq->tasks_timeline = RB_ROOT;
9147 INIT_LIST_HEAD(&cfs_rq->tasks);
9148 #ifdef CONFIG_FAIR_GROUP_SCHED
9149 cfs_rq->rq = rq;
9150 #endif
9151 cfs_rq->min_vruntime = (u64)(-(1LL << 20));
9152 }
9153
9154 static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
9155 {
9156 struct rt_prio_array *array;
9157 int i;
9158
9159 array = &rt_rq->active;
9160 for (i = 0; i < MAX_RT_PRIO; i++) {
9161 INIT_LIST_HEAD(array->queue + i);
9162 __clear_bit(i, array->bitmap);
9163 }
9164 /* delimiter for bitsearch: */
9165 __set_bit(MAX_RT_PRIO, array->bitmap);
9166
9167 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
9168 rt_rq->highest_prio.curr = MAX_RT_PRIO;
9169 #ifdef CONFIG_SMP
9170 rt_rq->highest_prio.next = MAX_RT_PRIO;
9171 #endif
9172 #endif
9173 #ifdef CONFIG_SMP
9174 rt_rq->rt_nr_migratory = 0;
9175 rt_rq->overloaded = 0;
9176 plist_head_init(&rt_rq->pushable_tasks, &rq->lock);
9177 #endif
9178
9179 rt_rq->rt_time = 0;
9180 rt_rq->rt_throttled = 0;
9181 rt_rq->rt_runtime = 0;
9182 spin_lock_init(&rt_rq->rt_runtime_lock);
9183
9184 #ifdef CONFIG_RT_GROUP_SCHED
9185 rt_rq->rt_nr_boosted = 0;
9186 rt_rq->rq = rq;
9187 #endif
9188 }
9189
9190 #ifdef CONFIG_FAIR_GROUP_SCHED
9191 static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
9192 struct sched_entity *se, int cpu, int add,
9193 struct sched_entity *parent)
9194 {
9195 struct rq *rq = cpu_rq(cpu);
9196 tg->cfs_rq[cpu] = cfs_rq;
9197 init_cfs_rq(cfs_rq, rq);
9198 cfs_rq->tg = tg;
9199 if (add)
9200 list_add(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
9201
9202 tg->se[cpu] = se;
9203 /* se could be NULL for init_task_group */
9204 if (!se)
9205 return;
9206
9207 if (!parent)
9208 se->cfs_rq = &rq->cfs;
9209 else
9210 se->cfs_rq = parent->my_q;
9211
9212 se->my_q = cfs_rq;
9213 se->load.weight = tg->shares;
9214 se->load.inv_weight = 0;
9215 se->parent = parent;
9216 }
9217 #endif
9218
9219 #ifdef CONFIG_RT_GROUP_SCHED
9220 static void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
9221 struct sched_rt_entity *rt_se, int cpu, int add,
9222 struct sched_rt_entity *parent)
9223 {
9224 struct rq *rq = cpu_rq(cpu);
9225
9226 tg->rt_rq[cpu] = rt_rq;
9227 init_rt_rq(rt_rq, rq);
9228 rt_rq->tg = tg;
9229 rt_rq->rt_se = rt_se;
9230 rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
9231 if (add)
9232 list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
9233
9234 tg->rt_se[cpu] = rt_se;
9235 if (!rt_se)
9236 return;
9237
9238 if (!parent)
9239 rt_se->rt_rq = &rq->rt;
9240 else
9241 rt_se->rt_rq = parent->my_q;
9242
9243 rt_se->my_q = rt_rq;
9244 rt_se->parent = parent;
9245 INIT_LIST_HEAD(&rt_se->run_list);
9246 }
9247 #endif
9248
9249 void __init sched_init(void)
9250 {
9251 int i, j;
9252 unsigned long alloc_size = 0, ptr;
9253
9254 #ifdef CONFIG_FAIR_GROUP_SCHED
9255 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
9256 #endif
9257 #ifdef CONFIG_RT_GROUP_SCHED
9258 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
9259 #endif
9260 #ifdef CONFIG_USER_SCHED
9261 alloc_size *= 2;
9262 #endif
9263 #ifdef CONFIG_CPUMASK_OFFSTACK
9264 alloc_size += num_possible_cpus() * cpumask_size();
9265 #endif
9266 /*
9267 * As sched_init() is called before page_alloc is setup,
9268 * we use alloc_bootmem().
9269 */
9270 if (alloc_size) {
9271 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
9272
9273 #ifdef CONFIG_FAIR_GROUP_SCHED
9274 init_task_group.se = (struct sched_entity **)ptr;
9275 ptr += nr_cpu_ids * sizeof(void **);
9276
9277 init_task_group.cfs_rq = (struct cfs_rq **)ptr;
9278 ptr += nr_cpu_ids * sizeof(void **);
9279
9280 #ifdef CONFIG_USER_SCHED
9281 root_task_group.se = (struct sched_entity **)ptr;
9282 ptr += nr_cpu_ids * sizeof(void **);
9283
9284 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
9285 ptr += nr_cpu_ids * sizeof(void **);
9286 #endif /* CONFIG_USER_SCHED */
9287 #endif /* CONFIG_FAIR_GROUP_SCHED */
9288 #ifdef CONFIG_RT_GROUP_SCHED
9289 init_task_group.rt_se = (struct sched_rt_entity **)ptr;
9290 ptr += nr_cpu_ids * sizeof(void **);
9291
9292 init_task_group.rt_rq = (struct rt_rq **)ptr;
9293 ptr += nr_cpu_ids * sizeof(void **);
9294
9295 #ifdef CONFIG_USER_SCHED
9296 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
9297 ptr += nr_cpu_ids * sizeof(void **);
9298
9299 root_task_group.rt_rq = (struct rt_rq **)ptr;
9300 ptr += nr_cpu_ids * sizeof(void **);
9301 #endif /* CONFIG_USER_SCHED */
9302 #endif /* CONFIG_RT_GROUP_SCHED */
9303 #ifdef CONFIG_CPUMASK_OFFSTACK
9304 for_each_possible_cpu(i) {
9305 per_cpu(load_balance_tmpmask, i) = (void *)ptr;
9306 ptr += cpumask_size();
9307 }
9308 #endif /* CONFIG_CPUMASK_OFFSTACK */
9309 }
9310
9311 #ifdef CONFIG_SMP
9312 init_defrootdomain();
9313 #endif
9314
9315 init_rt_bandwidth(&def_rt_bandwidth,
9316 global_rt_period(), global_rt_runtime());
9317
9318 #ifdef CONFIG_RT_GROUP_SCHED
9319 init_rt_bandwidth(&init_task_group.rt_bandwidth,
9320 global_rt_period(), global_rt_runtime());
9321 #ifdef CONFIG_USER_SCHED
9322 init_rt_bandwidth(&root_task_group.rt_bandwidth,
9323 global_rt_period(), RUNTIME_INF);
9324 #endif /* CONFIG_USER_SCHED */
9325 #endif /* CONFIG_RT_GROUP_SCHED */
9326
9327 #ifdef CONFIG_GROUP_SCHED
9328 list_add(&init_task_group.list, &task_groups);
9329 INIT_LIST_HEAD(&init_task_group.children);
9330
9331 #ifdef CONFIG_USER_SCHED
9332 INIT_LIST_HEAD(&root_task_group.children);
9333 init_task_group.parent = &root_task_group;
9334 list_add(&init_task_group.siblings, &root_task_group.children);
9335 #endif /* CONFIG_USER_SCHED */
9336 #endif /* CONFIG_GROUP_SCHED */
9337
9338 for_each_possible_cpu(i) {
9339 struct rq *rq;
9340
9341 rq = cpu_rq(i);
9342 spin_lock_init(&rq->lock);
9343 rq->nr_running = 0;
9344 rq->calc_load_active = 0;
9345 rq->calc_load_update = jiffies + LOAD_FREQ;
9346 init_cfs_rq(&rq->cfs, rq);
9347 init_rt_rq(&rq->rt, rq);
9348 #ifdef CONFIG_FAIR_GROUP_SCHED
9349 init_task_group.shares = init_task_group_load;
9350 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
9351 #ifdef CONFIG_CGROUP_SCHED
9352 /*
9353 * How much cpu bandwidth does init_task_group get?
9354 *
9355 * In case of task-groups formed thr' the cgroup filesystem, it
9356 * gets 100% of the cpu resources in the system. This overall
9357 * system cpu resource is divided among the tasks of
9358 * init_task_group and its child task-groups in a fair manner,
9359 * based on each entity's (task or task-group's) weight
9360 * (se->load.weight).
9361 *
9362 * In other words, if init_task_group has 10 tasks of weight
9363 * 1024) and two child groups A0 and A1 (of weight 1024 each),
9364 * then A0's share of the cpu resource is:
9365 *
9366 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
9367 *
9368 * We achieve this by letting init_task_group's tasks sit
9369 * directly in rq->cfs (i.e init_task_group->se[] = NULL).
9370 */
9371 init_tg_cfs_entry(&init_task_group, &rq->cfs, NULL, i, 1, NULL);
9372 #elif defined CONFIG_USER_SCHED
9373 root_task_group.shares = NICE_0_LOAD;
9374 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, 0, NULL);
9375 /*
9376 * In case of task-groups formed thr' the user id of tasks,
9377 * init_task_group represents tasks belonging to root user.
9378 * Hence it forms a sibling of all subsequent groups formed.
9379 * In this case, init_task_group gets only a fraction of overall
9380 * system cpu resource, based on the weight assigned to root
9381 * user's cpu share (INIT_TASK_GROUP_LOAD). This is accomplished
9382 * by letting tasks of init_task_group sit in a separate cfs_rq
9383 * (init_cfs_rq) and having one entity represent this group of
9384 * tasks in rq->cfs (i.e init_task_group->se[] != NULL).
9385 */
9386 init_tg_cfs_entry(&init_task_group,
9387 &per_cpu(init_cfs_rq, i),
9388 &per_cpu(init_sched_entity, i), i, 1,
9389 root_task_group.se[i]);
9390
9391 #endif
9392 #endif /* CONFIG_FAIR_GROUP_SCHED */
9393
9394 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
9395 #ifdef CONFIG_RT_GROUP_SCHED
9396 INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
9397 #ifdef CONFIG_CGROUP_SCHED
9398 init_tg_rt_entry(&init_task_group, &rq->rt, NULL, i, 1, NULL);
9399 #elif defined CONFIG_USER_SCHED
9400 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, 0, NULL);
9401 init_tg_rt_entry(&init_task_group,
9402 &per_cpu(init_rt_rq, i),
9403 &per_cpu(init_sched_rt_entity, i), i, 1,
9404 root_task_group.rt_se[i]);
9405 #endif
9406 #endif
9407
9408 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
9409 rq->cpu_load[j] = 0;
9410 #ifdef CONFIG_SMP
9411 rq->sd = NULL;
9412 rq->rd = NULL;
9413 rq->active_balance = 0;
9414 rq->next_balance = jiffies;
9415 rq->push_cpu = 0;
9416 rq->cpu = i;
9417 rq->online = 0;
9418 rq->migration_thread = NULL;
9419 INIT_LIST_HEAD(&rq->migration_queue);
9420 rq_attach_root(rq, &def_root_domain);
9421 #endif
9422 init_rq_hrtick(rq);
9423 atomic_set(&rq->nr_iowait, 0);
9424 }
9425
9426 set_load_weight(&init_task);
9427
9428 #ifdef CONFIG_PREEMPT_NOTIFIERS
9429 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
9430 #endif
9431
9432 #ifdef CONFIG_SMP
9433 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
9434 #endif
9435
9436 #ifdef CONFIG_RT_MUTEXES
9437 plist_head_init(&init_task.pi_waiters, &init_task.pi_lock);
9438 #endif
9439
9440 /*
9441 * The boot idle thread does lazy MMU switching as well:
9442 */
9443 atomic_inc(&init_mm.mm_count);
9444 enter_lazy_tlb(&init_mm, current);
9445
9446 /*
9447 * Make us the idle thread. Technically, schedule() should not be
9448 * called from this thread, however somewhere below it might be,
9449 * but because we are the idle thread, we just pick up running again
9450 * when this runqueue becomes "idle".
9451 */
9452 init_idle(current, smp_processor_id());
9453
9454 calc_load_update = jiffies + LOAD_FREQ;
9455
9456 /*
9457 * During early bootup we pretend to be a normal task:
9458 */
9459 current->sched_class = &fair_sched_class;
9460
9461 /* Allocate the nohz_cpu_mask if CONFIG_CPUMASK_OFFSTACK */
9462 alloc_cpumask_var(&nohz_cpu_mask, GFP_NOWAIT);
9463 #ifdef CONFIG_SMP
9464 #ifdef CONFIG_NO_HZ
9465 alloc_cpumask_var(&nohz.cpu_mask, GFP_NOWAIT);
9466 alloc_cpumask_var(&nohz.ilb_grp_nohz_mask, GFP_NOWAIT);
9467 #endif
9468 alloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
9469 #endif /* SMP */
9470
9471 perf_counter_init();
9472
9473 scheduler_running = 1;
9474 }
9475
9476 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
9477 void __might_sleep(char *file, int line)
9478 {
9479 #ifdef in_atomic
9480 static unsigned long prev_jiffy; /* ratelimiting */
9481
9482 if ((!in_atomic() && !irqs_disabled()) ||
9483 system_state != SYSTEM_RUNNING || oops_in_progress)
9484 return;
9485 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
9486 return;
9487 prev_jiffy = jiffies;
9488
9489 printk(KERN_ERR
9490 "BUG: sleeping function called from invalid context at %s:%d\n",
9491 file, line);
9492 printk(KERN_ERR
9493 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
9494 in_atomic(), irqs_disabled(),
9495 current->pid, current->comm);
9496
9497 debug_show_held_locks(current);
9498 if (irqs_disabled())
9499 print_irqtrace_events(current);
9500 dump_stack();
9501 #endif
9502 }
9503 EXPORT_SYMBOL(__might_sleep);
9504 #endif
9505
9506 #ifdef CONFIG_MAGIC_SYSRQ
9507 static void normalize_task(struct rq *rq, struct task_struct *p)
9508 {
9509 int on_rq;
9510
9511 update_rq_clock(rq);
9512 on_rq = p->se.on_rq;
9513 if (on_rq)
9514 deactivate_task(rq, p, 0);
9515 __setscheduler(rq, p, SCHED_NORMAL, 0);
9516 if (on_rq) {
9517 activate_task(rq, p, 0);
9518 resched_task(rq->curr);
9519 }
9520 }
9521
9522 void normalize_rt_tasks(void)
9523 {
9524 struct task_struct *g, *p;
9525 unsigned long flags;
9526 struct rq *rq;
9527
9528 read_lock_irqsave(&tasklist_lock, flags);
9529 do_each_thread(g, p) {
9530 /*
9531 * Only normalize user tasks:
9532 */
9533 if (!p->mm)
9534 continue;
9535
9536 p->se.exec_start = 0;
9537 #ifdef CONFIG_SCHEDSTATS
9538 p->se.wait_start = 0;
9539 p->se.sleep_start = 0;
9540 p->se.block_start = 0;
9541 #endif
9542
9543 if (!rt_task(p)) {
9544 /*
9545 * Renice negative nice level userspace
9546 * tasks back to 0:
9547 */
9548 if (TASK_NICE(p) < 0 && p->mm)
9549 set_user_nice(p, 0);
9550 continue;
9551 }
9552
9553 spin_lock(&p->pi_lock);
9554 rq = __task_rq_lock(p);
9555
9556 normalize_task(rq, p);
9557
9558 __task_rq_unlock(rq);
9559 spin_unlock(&p->pi_lock);
9560 } while_each_thread(g, p);
9561
9562 read_unlock_irqrestore(&tasklist_lock, flags);
9563 }
9564
9565 #endif /* CONFIG_MAGIC_SYSRQ */
9566
9567 #ifdef CONFIG_IA64
9568 /*
9569 * These functions are only useful for the IA64 MCA handling.
9570 *
9571 * They can only be called when the whole system has been
9572 * stopped - every CPU needs to be quiescent, and no scheduling
9573 * activity can take place. Using them for anything else would
9574 * be a serious bug, and as a result, they aren't even visible
9575 * under any other configuration.
9576 */
9577
9578 /**
9579 * curr_task - return the current task for a given cpu.
9580 * @cpu: the processor in question.
9581 *
9582 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
9583 */
9584 struct task_struct *curr_task(int cpu)
9585 {
9586 return cpu_curr(cpu);
9587 }
9588
9589 /**
9590 * set_curr_task - set the current task for a given cpu.
9591 * @cpu: the processor in question.
9592 * @p: the task pointer to set.
9593 *
9594 * Description: This function must only be used when non-maskable interrupts
9595 * are serviced on a separate stack. It allows the architecture to switch the
9596 * notion of the current task on a cpu in a non-blocking manner. This function
9597 * must be called with all CPU's synchronized, and interrupts disabled, the
9598 * and caller must save the original value of the current task (see
9599 * curr_task() above) and restore that value before reenabling interrupts and
9600 * re-starting the system.
9601 *
9602 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
9603 */
9604 void set_curr_task(int cpu, struct task_struct *p)
9605 {
9606 cpu_curr(cpu) = p;
9607 }
9608
9609 #endif
9610
9611 #ifdef CONFIG_FAIR_GROUP_SCHED
9612 static void free_fair_sched_group(struct task_group *tg)
9613 {
9614 int i;
9615
9616 for_each_possible_cpu(i) {
9617 if (tg->cfs_rq)
9618 kfree(tg->cfs_rq[i]);
9619 if (tg->se)
9620 kfree(tg->se[i]);
9621 }
9622
9623 kfree(tg->cfs_rq);
9624 kfree(tg->se);
9625 }
9626
9627 static
9628 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
9629 {
9630 struct cfs_rq *cfs_rq;
9631 struct sched_entity *se;
9632 struct rq *rq;
9633 int i;
9634
9635 tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL);
9636 if (!tg->cfs_rq)
9637 goto err;
9638 tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL);
9639 if (!tg->se)
9640 goto err;
9641
9642 tg->shares = NICE_0_LOAD;
9643
9644 for_each_possible_cpu(i) {
9645 rq = cpu_rq(i);
9646
9647 cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
9648 GFP_KERNEL, cpu_to_node(i));
9649 if (!cfs_rq)
9650 goto err;
9651
9652 se = kzalloc_node(sizeof(struct sched_entity),
9653 GFP_KERNEL, cpu_to_node(i));
9654 if (!se)
9655 goto err;
9656
9657 init_tg_cfs_entry(tg, cfs_rq, se, i, 0, parent->se[i]);
9658 }
9659
9660 return 1;
9661
9662 err:
9663 return 0;
9664 }
9665
9666 static inline void register_fair_sched_group(struct task_group *tg, int cpu)
9667 {
9668 list_add_rcu(&tg->cfs_rq[cpu]->leaf_cfs_rq_list,
9669 &cpu_rq(cpu)->leaf_cfs_rq_list);
9670 }
9671
9672 static inline void unregister_fair_sched_group(struct task_group *tg, int cpu)
9673 {
9674 list_del_rcu(&tg->cfs_rq[cpu]->leaf_cfs_rq_list);
9675 }
9676 #else /* !CONFG_FAIR_GROUP_SCHED */
9677 static inline void free_fair_sched_group(struct task_group *tg)
9678 {
9679 }
9680
9681 static inline
9682 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
9683 {
9684 return 1;
9685 }
9686
9687 static inline void register_fair_sched_group(struct task_group *tg, int cpu)
9688 {
9689 }
9690
9691 static inline void unregister_fair_sched_group(struct task_group *tg, int cpu)
9692 {
9693 }
9694 #endif /* CONFIG_FAIR_GROUP_SCHED */
9695
9696 #ifdef CONFIG_RT_GROUP_SCHED
9697 static void free_rt_sched_group(struct task_group *tg)
9698 {
9699 int i;
9700
9701 destroy_rt_bandwidth(&tg->rt_bandwidth);
9702
9703 for_each_possible_cpu(i) {
9704 if (tg->rt_rq)
9705 kfree(tg->rt_rq[i]);
9706 if (tg->rt_se)
9707 kfree(tg->rt_se[i]);
9708 }
9709
9710 kfree(tg->rt_rq);
9711 kfree(tg->rt_se);
9712 }
9713
9714 static
9715 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
9716 {
9717 struct rt_rq *rt_rq;
9718 struct sched_rt_entity *rt_se;
9719 struct rq *rq;
9720 int i;
9721
9722 tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
9723 if (!tg->rt_rq)
9724 goto err;
9725 tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
9726 if (!tg->rt_se)
9727 goto err;
9728
9729 init_rt_bandwidth(&tg->rt_bandwidth,
9730 ktime_to_ns(def_rt_bandwidth.rt_period), 0);
9731
9732 for_each_possible_cpu(i) {
9733 rq = cpu_rq(i);
9734
9735 rt_rq = kzalloc_node(sizeof(struct rt_rq),
9736 GFP_KERNEL, cpu_to_node(i));
9737 if (!rt_rq)
9738 goto err;
9739
9740 rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
9741 GFP_KERNEL, cpu_to_node(i));
9742 if (!rt_se)
9743 goto err;
9744
9745 init_tg_rt_entry(tg, rt_rq, rt_se, i, 0, parent->rt_se[i]);
9746 }
9747
9748 return 1;
9749
9750 err:
9751 return 0;
9752 }
9753
9754 static inline void register_rt_sched_group(struct task_group *tg, int cpu)
9755 {
9756 list_add_rcu(&tg->rt_rq[cpu]->leaf_rt_rq_list,
9757 &cpu_rq(cpu)->leaf_rt_rq_list);
9758 }
9759
9760 static inline void unregister_rt_sched_group(struct task_group *tg, int cpu)
9761 {
9762 list_del_rcu(&tg->rt_rq[cpu]->leaf_rt_rq_list);
9763 }
9764 #else /* !CONFIG_RT_GROUP_SCHED */
9765 static inline void free_rt_sched_group(struct task_group *tg)
9766 {
9767 }
9768
9769 static inline
9770 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
9771 {
9772 return 1;
9773 }
9774
9775 static inline void register_rt_sched_group(struct task_group *tg, int cpu)
9776 {
9777 }
9778
9779 static inline void unregister_rt_sched_group(struct task_group *tg, int cpu)
9780 {
9781 }
9782 #endif /* CONFIG_RT_GROUP_SCHED */
9783
9784 #ifdef CONFIG_GROUP_SCHED
9785 static void free_sched_group(struct task_group *tg)
9786 {
9787 free_fair_sched_group(tg);
9788 free_rt_sched_group(tg);
9789 kfree(tg);
9790 }
9791
9792 /* allocate runqueue etc for a new task group */
9793 struct task_group *sched_create_group(struct task_group *parent)
9794 {
9795 struct task_group *tg;
9796 unsigned long flags;
9797 int i;
9798
9799 tg = kzalloc(sizeof(*tg), GFP_KERNEL);
9800 if (!tg)
9801 return ERR_PTR(-ENOMEM);
9802
9803 if (!alloc_fair_sched_group(tg, parent))
9804 goto err;
9805
9806 if (!alloc_rt_sched_group(tg, parent))
9807 goto err;
9808
9809 spin_lock_irqsave(&task_group_lock, flags);
9810 for_each_possible_cpu(i) {
9811 register_fair_sched_group(tg, i);
9812 register_rt_sched_group(tg, i);
9813 }
9814 list_add_rcu(&tg->list, &task_groups);
9815
9816 WARN_ON(!parent); /* root should already exist */
9817
9818 tg->parent = parent;
9819 INIT_LIST_HEAD(&tg->children);
9820 list_add_rcu(&tg->siblings, &parent->children);
9821 spin_unlock_irqrestore(&task_group_lock, flags);
9822
9823 return tg;
9824
9825 err:
9826 free_sched_group(tg);
9827 return ERR_PTR(-ENOMEM);
9828 }
9829
9830 /* rcu callback to free various structures associated with a task group */
9831 static void free_sched_group_rcu(struct rcu_head *rhp)
9832 {
9833 /* now it should be safe to free those cfs_rqs */
9834 free_sched_group(container_of(rhp, struct task_group, rcu));
9835 }
9836
9837 /* Destroy runqueue etc associated with a task group */
9838 void sched_destroy_group(struct task_group *tg)
9839 {
9840 unsigned long flags;
9841 int i;
9842
9843 spin_lock_irqsave(&task_group_lock, flags);
9844 for_each_possible_cpu(i) {
9845 unregister_fair_sched_group(tg, i);
9846 unregister_rt_sched_group(tg, i);
9847 }
9848 list_del_rcu(&tg->list);
9849 list_del_rcu(&tg->siblings);
9850 spin_unlock_irqrestore(&task_group_lock, flags);
9851
9852 /* wait for possible concurrent references to cfs_rqs complete */
9853 call_rcu(&tg->rcu, free_sched_group_rcu);
9854 }
9855
9856 /* change task's runqueue when it moves between groups.
9857 * The caller of this function should have put the task in its new group
9858 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
9859 * reflect its new group.
9860 */
9861 void sched_move_task(struct task_struct *tsk)
9862 {
9863 int on_rq, running;
9864 unsigned long flags;
9865 struct rq *rq;
9866
9867 rq = task_rq_lock(tsk, &flags);
9868
9869 update_rq_clock(rq);
9870
9871 running = task_current(rq, tsk);
9872 on_rq = tsk->se.on_rq;
9873
9874 if (on_rq)
9875 dequeue_task(rq, tsk, 0);
9876 if (unlikely(running))
9877 tsk->sched_class->put_prev_task(rq, tsk);
9878
9879 set_task_rq(tsk, task_cpu(tsk));
9880
9881 #ifdef CONFIG_FAIR_GROUP_SCHED
9882 if (tsk->sched_class->moved_group)
9883 tsk->sched_class->moved_group(tsk);
9884 #endif
9885
9886 if (unlikely(running))
9887 tsk->sched_class->set_curr_task(rq);
9888 if (on_rq)
9889 enqueue_task(rq, tsk, 0);
9890
9891 task_rq_unlock(rq, &flags);
9892 }
9893 #endif /* CONFIG_GROUP_SCHED */
9894
9895 #ifdef CONFIG_FAIR_GROUP_SCHED
9896 static void __set_se_shares(struct sched_entity *se, unsigned long shares)
9897 {
9898 struct cfs_rq *cfs_rq = se->cfs_rq;
9899 int on_rq;
9900
9901 on_rq = se->on_rq;
9902 if (on_rq)
9903 dequeue_entity(cfs_rq, se, 0);
9904
9905 se->load.weight = shares;
9906 se->load.inv_weight = 0;
9907
9908 if (on_rq)
9909 enqueue_entity(cfs_rq, se, 0);
9910 }
9911
9912 static void set_se_shares(struct sched_entity *se, unsigned long shares)
9913 {
9914 struct cfs_rq *cfs_rq = se->cfs_rq;
9915 struct rq *rq = cfs_rq->rq;
9916 unsigned long flags;
9917
9918 spin_lock_irqsave(&rq->lock, flags);
9919 __set_se_shares(se, shares);
9920 spin_unlock_irqrestore(&rq->lock, flags);
9921 }
9922
9923 static DEFINE_MUTEX(shares_mutex);
9924
9925 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
9926 {
9927 int i;
9928 unsigned long flags;
9929
9930 /*
9931 * We can't change the weight of the root cgroup.
9932 */
9933 if (!tg->se[0])
9934 return -EINVAL;
9935
9936 if (shares < MIN_SHARES)
9937 shares = MIN_SHARES;
9938 else if (shares > MAX_SHARES)
9939 shares = MAX_SHARES;
9940
9941 mutex_lock(&shares_mutex);
9942 if (tg->shares == shares)
9943 goto done;
9944
9945 spin_lock_irqsave(&task_group_lock, flags);
9946 for_each_possible_cpu(i)
9947 unregister_fair_sched_group(tg, i);
9948 list_del_rcu(&tg->siblings);
9949 spin_unlock_irqrestore(&task_group_lock, flags);
9950
9951 /* wait for any ongoing reference to this group to finish */
9952 synchronize_sched();
9953
9954 /*
9955 * Now we are free to modify the group's share on each cpu
9956 * w/o tripping rebalance_share or load_balance_fair.
9957 */
9958 tg->shares = shares;
9959 for_each_possible_cpu(i) {
9960 /*
9961 * force a rebalance
9962 */
9963 cfs_rq_set_shares(tg->cfs_rq[i], 0);
9964 set_se_shares(tg->se[i], shares);
9965 }
9966
9967 /*
9968 * Enable load balance activity on this group, by inserting it back on
9969 * each cpu's rq->leaf_cfs_rq_list.
9970 */
9971 spin_lock_irqsave(&task_group_lock, flags);
9972 for_each_possible_cpu(i)
9973 register_fair_sched_group(tg, i);
9974 list_add_rcu(&tg->siblings, &tg->parent->children);
9975 spin_unlock_irqrestore(&task_group_lock, flags);
9976 done:
9977 mutex_unlock(&shares_mutex);
9978 return 0;
9979 }
9980
9981 unsigned long sched_group_shares(struct task_group *tg)
9982 {
9983 return tg->shares;
9984 }
9985 #endif
9986
9987 #ifdef CONFIG_RT_GROUP_SCHED
9988 /*
9989 * Ensure that the real time constraints are schedulable.
9990 */
9991 static DEFINE_MUTEX(rt_constraints_mutex);
9992
9993 static unsigned long to_ratio(u64 period, u64 runtime)
9994 {
9995 if (runtime == RUNTIME_INF)
9996 return 1ULL << 20;
9997
9998 return div64_u64(runtime << 20, period);
9999 }
10000
10001 /* Must be called with tasklist_lock held */
10002 static inline int tg_has_rt_tasks(struct task_group *tg)
10003 {
10004 struct task_struct *g, *p;
10005
10006 do_each_thread(g, p) {
10007 if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg)
10008 return 1;
10009 } while_each_thread(g, p);
10010
10011 return 0;
10012 }
10013
10014 struct rt_schedulable_data {
10015 struct task_group *tg;
10016 u64 rt_period;
10017 u64 rt_runtime;
10018 };
10019
10020 static int tg_schedulable(struct task_group *tg, void *data)
10021 {
10022 struct rt_schedulable_data *d = data;
10023 struct task_group *child;
10024 unsigned long total, sum = 0;
10025 u64 period, runtime;
10026
10027 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
10028 runtime = tg->rt_bandwidth.rt_runtime;
10029
10030 if (tg == d->tg) {
10031 period = d->rt_period;
10032 runtime = d->rt_runtime;
10033 }
10034
10035 #ifdef CONFIG_USER_SCHED
10036 if (tg == &root_task_group) {
10037 period = global_rt_period();
10038 runtime = global_rt_runtime();
10039 }
10040 #endif
10041
10042 /*
10043 * Cannot have more runtime than the period.
10044 */
10045 if (runtime > period && runtime != RUNTIME_INF)
10046 return -EINVAL;
10047
10048 /*
10049 * Ensure we don't starve existing RT tasks.
10050 */
10051 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
10052 return -EBUSY;
10053
10054 total = to_ratio(period, runtime);
10055
10056 /*
10057 * Nobody can have more than the global setting allows.
10058 */
10059 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
10060 return -EINVAL;
10061
10062 /*
10063 * The sum of our children's runtime should not exceed our own.
10064 */
10065 list_for_each_entry_rcu(child, &tg->children, siblings) {
10066 period = ktime_to_ns(child->rt_bandwidth.rt_period);
10067 runtime = child->rt_bandwidth.rt_runtime;
10068
10069 if (child == d->tg) {
10070 period = d->rt_period;
10071 runtime = d->rt_runtime;
10072 }
10073
10074 sum += to_ratio(period, runtime);
10075 }
10076
10077 if (sum > total)
10078 return -EINVAL;
10079
10080 return 0;
10081 }
10082
10083 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
10084 {
10085 struct rt_schedulable_data data = {
10086 .tg = tg,
10087 .rt_period = period,
10088 .rt_runtime = runtime,
10089 };
10090
10091 return walk_tg_tree(tg_schedulable, tg_nop, &data);
10092 }
10093
10094 static int tg_set_bandwidth(struct task_group *tg,
10095 u64 rt_period, u64 rt_runtime)
10096 {
10097 int i, err = 0;
10098
10099 mutex_lock(&rt_constraints_mutex);
10100 read_lock(&tasklist_lock);
10101 err = __rt_schedulable(tg, rt_period, rt_runtime);
10102 if (err)
10103 goto unlock;
10104
10105 spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
10106 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
10107 tg->rt_bandwidth.rt_runtime = rt_runtime;
10108
10109 for_each_possible_cpu(i) {
10110 struct rt_rq *rt_rq = tg->rt_rq[i];
10111
10112 spin_lock(&rt_rq->rt_runtime_lock);
10113 rt_rq->rt_runtime = rt_runtime;
10114 spin_unlock(&rt_rq->rt_runtime_lock);
10115 }
10116 spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
10117 unlock:
10118 read_unlock(&tasklist_lock);
10119 mutex_unlock(&rt_constraints_mutex);
10120
10121 return err;
10122 }
10123
10124 int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
10125 {
10126 u64 rt_runtime, rt_period;
10127
10128 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
10129 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
10130 if (rt_runtime_us < 0)
10131 rt_runtime = RUNTIME_INF;
10132
10133 return tg_set_bandwidth(tg, rt_period, rt_runtime);
10134 }
10135
10136 long sched_group_rt_runtime(struct task_group *tg)
10137 {
10138 u64 rt_runtime_us;
10139
10140 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
10141 return -1;
10142
10143 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
10144 do_div(rt_runtime_us, NSEC_PER_USEC);
10145 return rt_runtime_us;
10146 }
10147
10148 int sched_group_set_rt_period(struct task_group *tg, long rt_period_us)
10149 {
10150 u64 rt_runtime, rt_period;
10151
10152 rt_period = (u64)rt_period_us * NSEC_PER_USEC;
10153 rt_runtime = tg->rt_bandwidth.rt_runtime;
10154
10155 if (rt_period == 0)
10156 return -EINVAL;
10157
10158 return tg_set_bandwidth(tg, rt_period, rt_runtime);
10159 }
10160
10161 long sched_group_rt_period(struct task_group *tg)
10162 {
10163 u64 rt_period_us;
10164
10165 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
10166 do_div(rt_period_us, NSEC_PER_USEC);
10167 return rt_period_us;
10168 }
10169
10170 static int sched_rt_global_constraints(void)
10171 {
10172 u64 runtime, period;
10173 int ret = 0;
10174
10175 if (sysctl_sched_rt_period <= 0)
10176 return -EINVAL;
10177
10178 runtime = global_rt_runtime();
10179 period = global_rt_period();
10180
10181 /*
10182 * Sanity check on the sysctl variables.
10183 */
10184 if (runtime > period && runtime != RUNTIME_INF)
10185 return -EINVAL;
10186
10187 mutex_lock(&rt_constraints_mutex);
10188 read_lock(&tasklist_lock);
10189 ret = __rt_schedulable(NULL, 0, 0);
10190 read_unlock(&tasklist_lock);
10191 mutex_unlock(&rt_constraints_mutex);
10192
10193 return ret;
10194 }
10195
10196 int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
10197 {
10198 /* Don't accept realtime tasks when there is no way for them to run */
10199 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
10200 return 0;
10201
10202 return 1;
10203 }
10204
10205 #else /* !CONFIG_RT_GROUP_SCHED */
10206 static int sched_rt_global_constraints(void)
10207 {
10208 unsigned long flags;
10209 int i;
10210
10211 if (sysctl_sched_rt_period <= 0)
10212 return -EINVAL;
10213
10214 /*
10215 * There's always some RT tasks in the root group
10216 * -- migration, kstopmachine etc..
10217 */
10218 if (sysctl_sched_rt_runtime == 0)
10219 return -EBUSY;
10220
10221 spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
10222 for_each_possible_cpu(i) {
10223 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
10224
10225 spin_lock(&rt_rq->rt_runtime_lock);
10226 rt_rq->rt_runtime = global_rt_runtime();
10227 spin_unlock(&rt_rq->rt_runtime_lock);
10228 }
10229 spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
10230
10231 return 0;
10232 }
10233 #endif /* CONFIG_RT_GROUP_SCHED */
10234
10235 int sched_rt_handler(struct ctl_table *table, int write,
10236 struct file *filp, void __user *buffer, size_t *lenp,
10237 loff_t *ppos)
10238 {
10239 int ret;
10240 int old_period, old_runtime;
10241 static DEFINE_MUTEX(mutex);
10242
10243 mutex_lock(&mutex);
10244 old_period = sysctl_sched_rt_period;
10245 old_runtime = sysctl_sched_rt_runtime;
10246
10247 ret = proc_dointvec(table, write, filp, buffer, lenp, ppos);
10248
10249 if (!ret && write) {
10250 ret = sched_rt_global_constraints();
10251 if (ret) {
10252 sysctl_sched_rt_period = old_period;
10253 sysctl_sched_rt_runtime = old_runtime;
10254 } else {
10255 def_rt_bandwidth.rt_runtime = global_rt_runtime();
10256 def_rt_bandwidth.rt_period =
10257 ns_to_ktime(global_rt_period());
10258 }
10259 }
10260 mutex_unlock(&mutex);
10261
10262 return ret;
10263 }
10264
10265 #ifdef CONFIG_CGROUP_SCHED
10266
10267 /* return corresponding task_group object of a cgroup */
10268 static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
10269 {
10270 return container_of(cgroup_subsys_state(cgrp, cpu_cgroup_subsys_id),
10271 struct task_group, css);
10272 }
10273
10274 static struct cgroup_subsys_state *
10275 cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
10276 {
10277 struct task_group *tg, *parent;
10278
10279 if (!cgrp->parent) {
10280 /* This is early initialization for the top cgroup */
10281 return &init_task_group.css;
10282 }
10283
10284 parent = cgroup_tg(cgrp->parent);
10285 tg = sched_create_group(parent);
10286 if (IS_ERR(tg))
10287 return ERR_PTR(-ENOMEM);
10288
10289 return &tg->css;
10290 }
10291
10292 static void
10293 cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
10294 {
10295 struct task_group *tg = cgroup_tg(cgrp);
10296
10297 sched_destroy_group(tg);
10298 }
10299
10300 static int
10301 cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
10302 struct task_struct *tsk)
10303 {
10304 #ifdef CONFIG_RT_GROUP_SCHED
10305 if (!sched_rt_can_attach(cgroup_tg(cgrp), tsk))
10306 return -EINVAL;
10307 #else
10308 /* We don't support RT-tasks being in separate groups */
10309 if (tsk->sched_class != &fair_sched_class)
10310 return -EINVAL;
10311 #endif
10312
10313 return 0;
10314 }
10315
10316 static void
10317 cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
10318 struct cgroup *old_cont, struct task_struct *tsk)
10319 {
10320 sched_move_task(tsk);
10321 }
10322
10323 #ifdef CONFIG_FAIR_GROUP_SCHED
10324 static int cpu_shares_write_u64(struct cgroup *cgrp, struct cftype *cftype,
10325 u64 shareval)
10326 {
10327 return sched_group_set_shares(cgroup_tg(cgrp), shareval);
10328 }
10329
10330 static u64 cpu_shares_read_u64(struct cgroup *cgrp, struct cftype *cft)
10331 {
10332 struct task_group *tg = cgroup_tg(cgrp);
10333
10334 return (u64) tg->shares;
10335 }
10336 #endif /* CONFIG_FAIR_GROUP_SCHED */
10337
10338 #ifdef CONFIG_RT_GROUP_SCHED
10339 static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft,
10340 s64 val)
10341 {
10342 return sched_group_set_rt_runtime(cgroup_tg(cgrp), val);
10343 }
10344
10345 static s64 cpu_rt_runtime_read(struct cgroup *cgrp, struct cftype *cft)
10346 {
10347 return sched_group_rt_runtime(cgroup_tg(cgrp));
10348 }
10349
10350 static int cpu_rt_period_write_uint(struct cgroup *cgrp, struct cftype *cftype,
10351 u64 rt_period_us)
10352 {
10353 return sched_group_set_rt_period(cgroup_tg(cgrp), rt_period_us);
10354 }
10355
10356 static u64 cpu_rt_period_read_uint(struct cgroup *cgrp, struct cftype *cft)
10357 {
10358 return sched_group_rt_period(cgroup_tg(cgrp));
10359 }
10360 #endif /* CONFIG_RT_GROUP_SCHED */
10361
10362 static struct cftype cpu_files[] = {
10363 #ifdef CONFIG_FAIR_GROUP_SCHED
10364 {
10365 .name = "shares",
10366 .read_u64 = cpu_shares_read_u64,
10367 .write_u64 = cpu_shares_write_u64,
10368 },
10369 #endif
10370 #ifdef CONFIG_RT_GROUP_SCHED
10371 {
10372 .name = "rt_runtime_us",
10373 .read_s64 = cpu_rt_runtime_read,
10374 .write_s64 = cpu_rt_runtime_write,
10375 },
10376 {
10377 .name = "rt_period_us",
10378 .read_u64 = cpu_rt_period_read_uint,
10379 .write_u64 = cpu_rt_period_write_uint,
10380 },
10381 #endif
10382 };
10383
10384 static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
10385 {
10386 return cgroup_add_files(cont, ss, cpu_files, ARRAY_SIZE(cpu_files));
10387 }
10388
10389 struct cgroup_subsys cpu_cgroup_subsys = {
10390 .name = "cpu",
10391 .create = cpu_cgroup_create,
10392 .destroy = cpu_cgroup_destroy,
10393 .can_attach = cpu_cgroup_can_attach,
10394 .attach = cpu_cgroup_attach,
10395 .populate = cpu_cgroup_populate,
10396 .subsys_id = cpu_cgroup_subsys_id,
10397 .early_init = 1,
10398 };
10399
10400 #endif /* CONFIG_CGROUP_SCHED */
10401
10402 #ifdef CONFIG_CGROUP_CPUACCT
10403
10404 /*
10405 * CPU accounting code for task groups.
10406 *
10407 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
10408 * (balbir@in.ibm.com).
10409 */
10410
10411 /* track cpu usage of a group of tasks and its child groups */
10412 struct cpuacct {
10413 struct cgroup_subsys_state css;
10414 /* cpuusage holds pointer to a u64-type object on every cpu */
10415 u64 *cpuusage;
10416 struct percpu_counter cpustat[CPUACCT_STAT_NSTATS];
10417 struct cpuacct *parent;
10418 };
10419
10420 struct cgroup_subsys cpuacct_subsys;
10421
10422 /* return cpu accounting group corresponding to this container */
10423 static inline struct cpuacct *cgroup_ca(struct cgroup *cgrp)
10424 {
10425 return container_of(cgroup_subsys_state(cgrp, cpuacct_subsys_id),
10426 struct cpuacct, css);
10427 }
10428
10429 /* return cpu accounting group to which this task belongs */
10430 static inline struct cpuacct *task_ca(struct task_struct *tsk)
10431 {
10432 return container_of(task_subsys_state(tsk, cpuacct_subsys_id),
10433 struct cpuacct, css);
10434 }
10435
10436 /* create a new cpu accounting group */
10437 static struct cgroup_subsys_state *cpuacct_create(
10438 struct cgroup_subsys *ss, struct cgroup *cgrp)
10439 {
10440 struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
10441 int i;
10442
10443 if (!ca)
10444 goto out;
10445
10446 ca->cpuusage = alloc_percpu(u64);
10447 if (!ca->cpuusage)
10448 goto out_free_ca;
10449
10450 for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
10451 if (percpu_counter_init(&ca->cpustat[i], 0))
10452 goto out_free_counters;
10453
10454 if (cgrp->parent)
10455 ca->parent = cgroup_ca(cgrp->parent);
10456
10457 return &ca->css;
10458
10459 out_free_counters:
10460 while (--i >= 0)
10461 percpu_counter_destroy(&ca->cpustat[i]);
10462 free_percpu(ca->cpuusage);
10463 out_free_ca:
10464 kfree(ca);
10465 out:
10466 return ERR_PTR(-ENOMEM);
10467 }
10468
10469 /* destroy an existing cpu accounting group */
10470 static void
10471 cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
10472 {
10473 struct cpuacct *ca = cgroup_ca(cgrp);
10474 int i;
10475
10476 for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
10477 percpu_counter_destroy(&ca->cpustat[i]);
10478 free_percpu(ca->cpuusage);
10479 kfree(ca);
10480 }
10481
10482 static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu)
10483 {
10484 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
10485 u64 data;
10486
10487 #ifndef CONFIG_64BIT
10488 /*
10489 * Take rq->lock to make 64-bit read safe on 32-bit platforms.
10490 */
10491 spin_lock_irq(&cpu_rq(cpu)->lock);
10492 data = *cpuusage;
10493 spin_unlock_irq(&cpu_rq(cpu)->lock);
10494 #else
10495 data = *cpuusage;
10496 #endif
10497
10498 return data;
10499 }
10500
10501 static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val)
10502 {
10503 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
10504
10505 #ifndef CONFIG_64BIT
10506 /*
10507 * Take rq->lock to make 64-bit write safe on 32-bit platforms.
10508 */
10509 spin_lock_irq(&cpu_rq(cpu)->lock);
10510 *cpuusage = val;
10511 spin_unlock_irq(&cpu_rq(cpu)->lock);
10512 #else
10513 *cpuusage = val;
10514 #endif
10515 }
10516
10517 /* return total cpu usage (in nanoseconds) of a group */
10518 static u64 cpuusage_read(struct cgroup *cgrp, struct cftype *cft)
10519 {
10520 struct cpuacct *ca = cgroup_ca(cgrp);
10521 u64 totalcpuusage = 0;
10522 int i;
10523
10524 for_each_present_cpu(i)
10525 totalcpuusage += cpuacct_cpuusage_read(ca, i);
10526
10527 return totalcpuusage;
10528 }
10529
10530 static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype,
10531 u64 reset)
10532 {
10533 struct cpuacct *ca = cgroup_ca(cgrp);
10534 int err = 0;
10535 int i;
10536
10537 if (reset) {
10538 err = -EINVAL;
10539 goto out;
10540 }
10541
10542 for_each_present_cpu(i)
10543 cpuacct_cpuusage_write(ca, i, 0);
10544
10545 out:
10546 return err;
10547 }
10548
10549 static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft,
10550 struct seq_file *m)
10551 {
10552 struct cpuacct *ca = cgroup_ca(cgroup);
10553 u64 percpu;
10554 int i;
10555
10556 for_each_present_cpu(i) {
10557 percpu = cpuacct_cpuusage_read(ca, i);
10558 seq_printf(m, "%llu ", (unsigned long long) percpu);
10559 }
10560 seq_printf(m, "\n");
10561 return 0;
10562 }
10563
10564 static const char *cpuacct_stat_desc[] = {
10565 [CPUACCT_STAT_USER] = "user",
10566 [CPUACCT_STAT_SYSTEM] = "system",
10567 };
10568
10569 static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
10570 struct cgroup_map_cb *cb)
10571 {
10572 struct cpuacct *ca = cgroup_ca(cgrp);
10573 int i;
10574
10575 for (i = 0; i < CPUACCT_STAT_NSTATS; i++) {
10576 s64 val = percpu_counter_read(&ca->cpustat[i]);
10577 val = cputime64_to_clock_t(val);
10578 cb->fill(cb, cpuacct_stat_desc[i], val);
10579 }
10580 return 0;
10581 }
10582
10583 static struct cftype files[] = {
10584 {
10585 .name = "usage",
10586 .read_u64 = cpuusage_read,
10587 .write_u64 = cpuusage_write,
10588 },
10589 {
10590 .name = "usage_percpu",
10591 .read_seq_string = cpuacct_percpu_seq_read,
10592 },
10593 {
10594 .name = "stat",
10595 .read_map = cpuacct_stats_show,
10596 },
10597 };
10598
10599 static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
10600 {
10601 return cgroup_add_files(cgrp, ss, files, ARRAY_SIZE(files));
10602 }
10603
10604 /*
10605 * charge this task's execution time to its accounting group.
10606 *
10607 * called with rq->lock held.
10608 */
10609 static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
10610 {
10611 struct cpuacct *ca;
10612 int cpu;
10613
10614 if (unlikely(!cpuacct_subsys.active))
10615 return;
10616
10617 cpu = task_cpu(tsk);
10618
10619 rcu_read_lock();
10620
10621 ca = task_ca(tsk);
10622
10623 for (; ca; ca = ca->parent) {
10624 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
10625 *cpuusage += cputime;
10626 }
10627
10628 rcu_read_unlock();
10629 }
10630
10631 /*
10632 * Charge the system/user time to the task's accounting group.
10633 */
10634 static void cpuacct_update_stats(struct task_struct *tsk,
10635 enum cpuacct_stat_index idx, cputime_t val)
10636 {
10637 struct cpuacct *ca;
10638
10639 if (unlikely(!cpuacct_subsys.active))
10640 return;
10641
10642 rcu_read_lock();
10643 ca = task_ca(tsk);
10644
10645 do {
10646 percpu_counter_add(&ca->cpustat[idx], val);
10647 ca = ca->parent;
10648 } while (ca);
10649 rcu_read_unlock();
10650 }
10651
10652 struct cgroup_subsys cpuacct_subsys = {
10653 .name = "cpuacct",
10654 .create = cpuacct_create,
10655 .destroy = cpuacct_destroy,
10656 .populate = cpuacct_populate,
10657 .subsys_id = cpuacct_subsys_id,
10658 };
10659 #endif /* CONFIG_CGROUP_CPUACCT */