4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
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
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
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
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/security.h>
43 #include <linux/notifier.h>
44 #include <linux/profile.h>
45 #include <linux/freezer.h>
46 #include <linux/vmalloc.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/smp.h>
51 #include <linux/threads.h>
52 #include <linux/timer.h>
53 #include <linux/rcupdate.h>
54 #include <linux/cpu.h>
55 #include <linux/cpuset.h>
56 #include <linux/percpu.h>
57 #include <linux/kthread.h>
58 #include <linux/seq_file.h>
59 #include <linux/sysctl.h>
60 #include <linux/syscalls.h>
61 #include <linux/times.h>
62 #include <linux/tsacct_kern.h>
63 #include <linux/kprobes.h>
64 #include <linux/delayacct.h>
65 #include <linux/reciprocal_div.h>
66 #include <linux/unistd.h>
67 #include <linux/pagemap.h>
68 #include <linux/hrtimer.h>
69 #include <linux/tick.h>
70 #include <linux/bootmem.h>
71 #include <linux/debugfs.h>
72 #include <linux/ctype.h>
75 #include <asm/irq_regs.h>
77 #include "sched_cpupri.h"
80 * Convert user-nice values [ -20 ... 0 ... 19 ]
81 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
84 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
85 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
86 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
89 * 'User priority' is the nice value converted to something we
90 * can work with better when scaling various scheduler parameters,
91 * it's a [ 0 ... 39 ] range.
93 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
94 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
95 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
98 * Helpers for converting nanosecond timing to jiffy resolution
100 #define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
102 #define NICE_0_LOAD SCHED_LOAD_SCALE
103 #define NICE_0_SHIFT SCHED_LOAD_SHIFT
106 * These are the 'tuning knobs' of the scheduler:
108 * default timeslice is 100 msecs (used only for SCHED_RR tasks).
109 * Timeslices get refilled after they expire.
111 #define DEF_TIMESLICE (100 * HZ / 1000)
114 * single value that denotes runtime == period, ie unlimited time.
116 #define RUNTIME_INF ((u64)~0ULL)
120 * Divide a load by a sched group cpu_power : (load / sg->__cpu_power)
121 * Since cpu_power is a 'constant', we can use a reciprocal divide.
123 static inline u32 sg_div_cpu_power(const struct sched_group *sg, u32 load)
125 return reciprocal_divide(load, sg->reciprocal_cpu_power);
129 * Each time a sched group cpu_power is changed,
130 * we must compute its reciprocal value
132 static inline void sg_inc_cpu_power(struct sched_group *sg, u32 val)
134 sg->__cpu_power += val;
135 sg->reciprocal_cpu_power = reciprocal_value(sg->__cpu_power);
139 static inline int rt_policy(int policy)
141 if (unlikely(policy == SCHED_FIFO || policy == SCHED_RR))
146 static inline int task_has_rt_policy(struct task_struct *p)
148 return rt_policy(p->policy);
152 * This is the priority-queue data structure of the RT scheduling class:
154 struct rt_prio_array {
155 DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
156 struct list_head queue[MAX_RT_PRIO];
159 struct rt_bandwidth {
160 /* nests inside the rq lock: */
161 spinlock_t rt_runtime_lock;
164 struct hrtimer rt_period_timer;
167 static struct rt_bandwidth def_rt_bandwidth;
169 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
171 static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
173 struct rt_bandwidth *rt_b =
174 container_of(timer, struct rt_bandwidth, rt_period_timer);
180 now = hrtimer_cb_get_time(timer);
181 overrun = hrtimer_forward(timer, now, rt_b->rt_period);
186 idle = do_sched_rt_period_timer(rt_b, overrun);
189 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
193 void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
195 rt_b->rt_period = ns_to_ktime(period);
196 rt_b->rt_runtime = runtime;
198 spin_lock_init(&rt_b->rt_runtime_lock);
200 hrtimer_init(&rt_b->rt_period_timer,
201 CLOCK_MONOTONIC, HRTIMER_MODE_REL);
202 rt_b->rt_period_timer.function = sched_rt_period_timer;
203 rt_b->rt_period_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ;
206 static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
210 if (rt_b->rt_runtime == RUNTIME_INF)
213 if (hrtimer_active(&rt_b->rt_period_timer))
216 spin_lock(&rt_b->rt_runtime_lock);
218 if (hrtimer_active(&rt_b->rt_period_timer))
221 now = hrtimer_cb_get_time(&rt_b->rt_period_timer);
222 hrtimer_forward(&rt_b->rt_period_timer, now, rt_b->rt_period);
223 hrtimer_start(&rt_b->rt_period_timer,
224 rt_b->rt_period_timer.expires,
227 spin_unlock(&rt_b->rt_runtime_lock);
230 #ifdef CONFIG_RT_GROUP_SCHED
231 static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
233 hrtimer_cancel(&rt_b->rt_period_timer);
238 * sched_domains_mutex serializes calls to arch_init_sched_domains,
239 * detach_destroy_domains and partition_sched_domains.
241 static DEFINE_MUTEX(sched_domains_mutex);
243 #ifdef CONFIG_GROUP_SCHED
245 #include <linux/cgroup.h>
249 static LIST_HEAD(task_groups);
251 /* task group related information */
253 #ifdef CONFIG_CGROUP_SCHED
254 struct cgroup_subsys_state css;
257 #ifdef CONFIG_FAIR_GROUP_SCHED
258 /* schedulable entities of this group on each cpu */
259 struct sched_entity **se;
260 /* runqueue "owned" by this group on each cpu */
261 struct cfs_rq **cfs_rq;
262 unsigned long shares;
265 #ifdef CONFIG_RT_GROUP_SCHED
266 struct sched_rt_entity **rt_se;
267 struct rt_rq **rt_rq;
269 struct rt_bandwidth rt_bandwidth;
273 struct list_head list;
275 struct task_group *parent;
276 struct list_head siblings;
277 struct list_head children;
280 #ifdef CONFIG_USER_SCHED
284 * Every UID task group (including init_task_group aka UID-0) will
285 * be a child to this group.
287 struct task_group root_task_group;
289 #ifdef CONFIG_FAIR_GROUP_SCHED
290 /* Default task group's sched entity on each cpu */
291 static DEFINE_PER_CPU(struct sched_entity, init_sched_entity);
292 /* Default task group's cfs_rq on each cpu */
293 static DEFINE_PER_CPU(struct cfs_rq, init_cfs_rq) ____cacheline_aligned_in_smp;
294 #endif /* CONFIG_FAIR_GROUP_SCHED */
296 #ifdef CONFIG_RT_GROUP_SCHED
297 static DEFINE_PER_CPU(struct sched_rt_entity, init_sched_rt_entity);
298 static DEFINE_PER_CPU(struct rt_rq, init_rt_rq) ____cacheline_aligned_in_smp;
299 #endif /* CONFIG_RT_GROUP_SCHED */
300 #else /* !CONFIG_FAIR_GROUP_SCHED */
301 #define root_task_group init_task_group
302 #endif /* CONFIG_FAIR_GROUP_SCHED */
304 /* task_group_lock serializes add/remove of task groups and also changes to
305 * a task group's cpu shares.
307 static DEFINE_SPINLOCK(task_group_lock);
309 #ifdef CONFIG_FAIR_GROUP_SCHED
310 #ifdef CONFIG_USER_SCHED
311 # define INIT_TASK_GROUP_LOAD (2*NICE_0_LOAD)
312 #else /* !CONFIG_USER_SCHED */
313 # define INIT_TASK_GROUP_LOAD NICE_0_LOAD
314 #endif /* CONFIG_USER_SCHED */
317 * A weight of 0 or 1 can cause arithmetics problems.
318 * A weight of a cfs_rq is the sum of weights of which entities
319 * are queued on this cfs_rq, so a weight of a entity should not be
320 * too large, so as the shares value of a task group.
321 * (The default weight is 1024 - so there's no practical
322 * limitation from this.)
325 #define MAX_SHARES (1UL << 18)
327 static int init_task_group_load = INIT_TASK_GROUP_LOAD;
330 /* Default task group.
331 * Every task in system belong to this group at bootup.
333 struct task_group init_task_group;
335 /* return group to which a task belongs */
336 static inline struct task_group *task_group(struct task_struct *p)
338 struct task_group *tg;
340 #ifdef CONFIG_USER_SCHED
342 #elif defined(CONFIG_CGROUP_SCHED)
343 tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
344 struct task_group, css);
346 tg = &init_task_group;
351 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
352 static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
354 #ifdef CONFIG_FAIR_GROUP_SCHED
355 p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
356 p->se.parent = task_group(p)->se[cpu];
359 #ifdef CONFIG_RT_GROUP_SCHED
360 p->rt.rt_rq = task_group(p)->rt_rq[cpu];
361 p->rt.parent = task_group(p)->rt_se[cpu];
367 static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
368 static inline struct task_group *task_group(struct task_struct *p)
373 #endif /* CONFIG_GROUP_SCHED */
375 /* CFS-related fields in a runqueue */
377 struct load_weight load;
378 unsigned long nr_running;
384 struct rb_root tasks_timeline;
385 struct rb_node *rb_leftmost;
387 struct list_head tasks;
388 struct list_head *balance_iterator;
391 * 'curr' points to currently running entity on this cfs_rq.
392 * It is set to NULL otherwise (i.e when none are currently running).
394 struct sched_entity *curr, *next;
396 unsigned long nr_spread_over;
398 #ifdef CONFIG_FAIR_GROUP_SCHED
399 struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
402 * leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
403 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
404 * (like users, containers etc.)
406 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
407 * list is used during load balance.
409 struct list_head leaf_cfs_rq_list;
410 struct task_group *tg; /* group that "owns" this runqueue */
414 * the part of load.weight contributed by tasks
416 unsigned long task_weight;
419 * h_load = weight * f(tg)
421 * Where f(tg) is the recursive weight fraction assigned to
424 unsigned long h_load;
427 * this cpu's part of tg->shares
429 unsigned long shares;
432 * load.weight at the time we set shares
434 unsigned long rq_weight;
439 /* Real-Time classes' related field in a runqueue: */
441 struct rt_prio_array active;
442 unsigned long rt_nr_running;
443 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
444 int highest_prio; /* highest queued rt task prio */
447 unsigned long rt_nr_migratory;
453 /* Nests inside the rq lock: */
454 spinlock_t rt_runtime_lock;
456 #ifdef CONFIG_RT_GROUP_SCHED
457 unsigned long rt_nr_boosted;
460 struct list_head leaf_rt_rq_list;
461 struct task_group *tg;
462 struct sched_rt_entity *rt_se;
469 * We add the notion of a root-domain which will be used to define per-domain
470 * variables. Each exclusive cpuset essentially defines an island domain by
471 * fully partitioning the member cpus from any other cpuset. Whenever a new
472 * exclusive cpuset is created, we also create and attach a new root-domain
482 * The "RT overload" flag: it gets set if a CPU has more than
483 * one runnable RT task.
488 struct cpupri cpupri;
493 * By default the system creates a single root-domain with all cpus as
494 * members (mimicking the global state we have today).
496 static struct root_domain def_root_domain;
501 * This is the main, per-CPU runqueue data structure.
503 * Locking rule: those places that want to lock multiple runqueues
504 * (such as the load balancing or the thread migration code), lock
505 * acquire operations must be ordered by ascending &runqueue.
512 * nr_running and cpu_load should be in the same cacheline because
513 * remote CPUs use both these fields when doing load calculation.
515 unsigned long nr_running;
516 #define CPU_LOAD_IDX_MAX 5
517 unsigned long cpu_load[CPU_LOAD_IDX_MAX];
518 unsigned char idle_at_tick;
520 unsigned long last_tick_seen;
521 unsigned char in_nohz_recently;
523 /* capture load from *all* tasks on this cpu: */
524 struct load_weight load;
525 unsigned long nr_load_updates;
531 #ifdef CONFIG_FAIR_GROUP_SCHED
532 /* list of leaf cfs_rq on this cpu: */
533 struct list_head leaf_cfs_rq_list;
535 #ifdef CONFIG_RT_GROUP_SCHED
536 struct list_head leaf_rt_rq_list;
540 * This is part of a global counter where only the total sum
541 * over all CPUs matters. A task can increase this counter on
542 * one CPU and if it got migrated afterwards it may decrease
543 * it on another CPU. Always updated under the runqueue lock:
545 unsigned long nr_uninterruptible;
547 struct task_struct *curr, *idle;
548 unsigned long next_balance;
549 struct mm_struct *prev_mm;
556 struct root_domain *rd;
557 struct sched_domain *sd;
559 /* For active balancing */
562 /* cpu of this runqueue: */
566 unsigned long avg_load_per_task;
568 struct task_struct *migration_thread;
569 struct list_head migration_queue;
572 #ifdef CONFIG_SCHED_HRTICK
573 unsigned long hrtick_flags;
574 ktime_t hrtick_expire;
575 struct hrtimer hrtick_timer;
578 #ifdef CONFIG_SCHEDSTATS
580 struct sched_info rq_sched_info;
582 /* sys_sched_yield() stats */
583 unsigned int yld_exp_empty;
584 unsigned int yld_act_empty;
585 unsigned int yld_both_empty;
586 unsigned int yld_count;
588 /* schedule() stats */
589 unsigned int sched_switch;
590 unsigned int sched_count;
591 unsigned int sched_goidle;
593 /* try_to_wake_up() stats */
594 unsigned int ttwu_count;
595 unsigned int ttwu_local;
598 unsigned int bkl_count;
600 struct lock_class_key rq_lock_key;
603 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
605 static inline void check_preempt_curr(struct rq *rq, struct task_struct *p)
607 rq->curr->sched_class->check_preempt_curr(rq, p);
610 static inline int cpu_of(struct rq *rq)
620 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
621 * See detach_destroy_domains: synchronize_sched for details.
623 * The domain tree of any CPU may only be accessed from within
624 * preempt-disabled sections.
626 #define for_each_domain(cpu, __sd) \
627 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
629 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
630 #define this_rq() (&__get_cpu_var(runqueues))
631 #define task_rq(p) cpu_rq(task_cpu(p))
632 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
634 static inline void update_rq_clock(struct rq *rq)
636 rq->clock = sched_clock_cpu(cpu_of(rq));
640 * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
642 #ifdef CONFIG_SCHED_DEBUG
643 # define const_debug __read_mostly
645 # define const_debug static const
649 * Debugging: various feature bits
652 #define SCHED_FEAT(name, enabled) \
653 __SCHED_FEAT_##name ,
656 #include "sched_features.h"
661 #define SCHED_FEAT(name, enabled) \
662 (1UL << __SCHED_FEAT_##name) * enabled |
664 const_debug unsigned int sysctl_sched_features =
665 #include "sched_features.h"
670 #ifdef CONFIG_SCHED_DEBUG
671 #define SCHED_FEAT(name, enabled) \
674 static __read_mostly char *sched_feat_names[] = {
675 #include "sched_features.h"
681 static int sched_feat_open(struct inode *inode, struct file *filp)
683 filp->private_data = inode->i_private;
688 sched_feat_read(struct file *filp, char __user *ubuf,
689 size_t cnt, loff_t *ppos)
696 for (i = 0; sched_feat_names[i]; i++) {
697 len += strlen(sched_feat_names[i]);
701 buf = kmalloc(len + 2, GFP_KERNEL);
705 for (i = 0; sched_feat_names[i]; i++) {
706 if (sysctl_sched_features & (1UL << i))
707 r += sprintf(buf + r, "%s ", sched_feat_names[i]);
709 r += sprintf(buf + r, "NO_%s ", sched_feat_names[i]);
712 r += sprintf(buf + r, "\n");
713 WARN_ON(r >= len + 2);
715 r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
723 sched_feat_write(struct file *filp, const char __user *ubuf,
724 size_t cnt, loff_t *ppos)
734 if (copy_from_user(&buf, ubuf, cnt))
739 if (strncmp(buf, "NO_", 3) == 0) {
744 for (i = 0; sched_feat_names[i]; i++) {
745 int len = strlen(sched_feat_names[i]);
747 if (strncmp(cmp, sched_feat_names[i], len) == 0) {
749 sysctl_sched_features &= ~(1UL << i);
751 sysctl_sched_features |= (1UL << i);
756 if (!sched_feat_names[i])
764 static struct file_operations sched_feat_fops = {
765 .open = sched_feat_open,
766 .read = sched_feat_read,
767 .write = sched_feat_write,
770 static __init int sched_init_debug(void)
772 debugfs_create_file("sched_features", 0644, NULL, NULL,
777 late_initcall(sched_init_debug);
781 #define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
784 * Number of tasks to iterate in a single balance run.
785 * Limited because this is done with IRQs disabled.
787 const_debug unsigned int sysctl_sched_nr_migrate = 32;
790 * ratelimit for updating the group shares.
793 const_debug unsigned int sysctl_sched_shares_ratelimit = 500000;
796 * period over which we measure -rt task cpu usage in us.
799 unsigned int sysctl_sched_rt_period = 1000000;
801 static __read_mostly int scheduler_running;
804 * part of the period that we allow rt tasks to run in us.
807 int sysctl_sched_rt_runtime = 950000;
809 static inline u64 global_rt_period(void)
811 return (u64)sysctl_sched_rt_period * NSEC_PER_USEC;
814 static inline u64 global_rt_runtime(void)
816 if (sysctl_sched_rt_period < 0)
819 return (u64)sysctl_sched_rt_runtime * NSEC_PER_USEC;
822 #ifndef prepare_arch_switch
823 # define prepare_arch_switch(next) do { } while (0)
825 #ifndef finish_arch_switch
826 # define finish_arch_switch(prev) do { } while (0)
829 static inline int task_current(struct rq *rq, struct task_struct *p)
831 return rq->curr == p;
834 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
835 static inline int task_running(struct rq *rq, struct task_struct *p)
837 return task_current(rq, p);
840 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
844 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
846 #ifdef CONFIG_DEBUG_SPINLOCK
847 /* this is a valid case when another task releases the spinlock */
848 rq->lock.owner = current;
851 * If we are tracking spinlock dependencies then we have to
852 * fix up the runqueue lock - which gets 'carried over' from
855 spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
857 spin_unlock_irq(&rq->lock);
860 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
861 static inline int task_running(struct rq *rq, struct task_struct *p)
866 return task_current(rq, p);
870 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
874 * We can optimise this out completely for !SMP, because the
875 * SMP rebalancing from interrupt is the only thing that cares
880 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
881 spin_unlock_irq(&rq->lock);
883 spin_unlock(&rq->lock);
887 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
891 * After ->oncpu is cleared, the task can be moved to a different CPU.
892 * We must ensure this doesn't happen until the switch is completely
898 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
902 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
905 * __task_rq_lock - lock the runqueue a given task resides on.
906 * Must be called interrupts disabled.
908 static inline struct rq *__task_rq_lock(struct task_struct *p)
912 struct rq *rq = task_rq(p);
913 spin_lock(&rq->lock);
914 if (likely(rq == task_rq(p)))
916 spin_unlock(&rq->lock);
921 * task_rq_lock - lock the runqueue a given task resides on and disable
922 * interrupts. Note the ordering: we can safely lookup the task_rq without
923 * explicitly disabling preemption.
925 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
931 local_irq_save(*flags);
933 spin_lock(&rq->lock);
934 if (likely(rq == task_rq(p)))
936 spin_unlock_irqrestore(&rq->lock, *flags);
940 static void __task_rq_unlock(struct rq *rq)
943 spin_unlock(&rq->lock);
946 static inline void task_rq_unlock(struct rq *rq, unsigned long *flags)
949 spin_unlock_irqrestore(&rq->lock, *flags);
953 * this_rq_lock - lock this runqueue and disable interrupts.
955 static struct rq *this_rq_lock(void)
962 spin_lock(&rq->lock);
967 static void __resched_task(struct task_struct *p, int tif_bit);
969 static inline void resched_task(struct task_struct *p)
971 __resched_task(p, TIF_NEED_RESCHED);
974 #ifdef CONFIG_SCHED_HRTICK
976 * Use HR-timers to deliver accurate preemption points.
978 * Its all a bit involved since we cannot program an hrt while holding the
979 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
982 * When we get rescheduled we reprogram the hrtick_timer outside of the
985 static inline void resched_hrt(struct task_struct *p)
987 __resched_task(p, TIF_HRTICK_RESCHED);
990 static inline void resched_rq(struct rq *rq)
994 spin_lock_irqsave(&rq->lock, flags);
995 resched_task(rq->curr);
996 spin_unlock_irqrestore(&rq->lock, flags);
1000 HRTICK_SET, /* re-programm hrtick_timer */
1001 HRTICK_RESET, /* not a new slice */
1002 HRTICK_BLOCK, /* stop hrtick operations */
1007 * - enabled by features
1008 * - hrtimer is actually high res
1010 static inline int hrtick_enabled(struct rq *rq)
1012 if (!sched_feat(HRTICK))
1014 if (unlikely(test_bit(HRTICK_BLOCK, &rq->hrtick_flags)))
1016 return hrtimer_is_hres_active(&rq->hrtick_timer);
1020 * Called to set the hrtick timer state.
1022 * called with rq->lock held and irqs disabled
1024 static void hrtick_start(struct rq *rq, u64 delay, int reset)
1026 assert_spin_locked(&rq->lock);
1029 * preempt at: now + delay
1032 ktime_add_ns(rq->hrtick_timer.base->get_time(), delay);
1034 * indicate we need to program the timer
1036 __set_bit(HRTICK_SET, &rq->hrtick_flags);
1038 __set_bit(HRTICK_RESET, &rq->hrtick_flags);
1041 * New slices are called from the schedule path and don't need a
1042 * forced reschedule.
1045 resched_hrt(rq->curr);
1048 static void hrtick_clear(struct rq *rq)
1050 if (hrtimer_active(&rq->hrtick_timer))
1051 hrtimer_cancel(&rq->hrtick_timer);
1055 * Update the timer from the possible pending state.
1057 static void hrtick_set(struct rq *rq)
1061 unsigned long flags;
1063 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
1065 spin_lock_irqsave(&rq->lock, flags);
1066 set = __test_and_clear_bit(HRTICK_SET, &rq->hrtick_flags);
1067 reset = __test_and_clear_bit(HRTICK_RESET, &rq->hrtick_flags);
1068 time = rq->hrtick_expire;
1069 clear_thread_flag(TIF_HRTICK_RESCHED);
1070 spin_unlock_irqrestore(&rq->lock, flags);
1073 hrtimer_start(&rq->hrtick_timer, time, HRTIMER_MODE_ABS);
1074 if (reset && !hrtimer_active(&rq->hrtick_timer))
1081 * High-resolution timer tick.
1082 * Runs from hardirq context with interrupts disabled.
1084 static enum hrtimer_restart hrtick(struct hrtimer *timer)
1086 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
1088 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
1090 spin_lock(&rq->lock);
1091 update_rq_clock(rq);
1092 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
1093 spin_unlock(&rq->lock);
1095 return HRTIMER_NORESTART;
1099 static void hotplug_hrtick_disable(int cpu)
1101 struct rq *rq = cpu_rq(cpu);
1102 unsigned long flags;
1104 spin_lock_irqsave(&rq->lock, flags);
1105 rq->hrtick_flags = 0;
1106 __set_bit(HRTICK_BLOCK, &rq->hrtick_flags);
1107 spin_unlock_irqrestore(&rq->lock, flags);
1112 static void hotplug_hrtick_enable(int cpu)
1114 struct rq *rq = cpu_rq(cpu);
1115 unsigned long flags;
1117 spin_lock_irqsave(&rq->lock, flags);
1118 __clear_bit(HRTICK_BLOCK, &rq->hrtick_flags);
1119 spin_unlock_irqrestore(&rq->lock, flags);
1123 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
1125 int cpu = (int)(long)hcpu;
1128 case CPU_UP_CANCELED:
1129 case CPU_UP_CANCELED_FROZEN:
1130 case CPU_DOWN_PREPARE:
1131 case CPU_DOWN_PREPARE_FROZEN:
1133 case CPU_DEAD_FROZEN:
1134 hotplug_hrtick_disable(cpu);
1137 case CPU_UP_PREPARE:
1138 case CPU_UP_PREPARE_FROZEN:
1139 case CPU_DOWN_FAILED:
1140 case CPU_DOWN_FAILED_FROZEN:
1142 case CPU_ONLINE_FROZEN:
1143 hotplug_hrtick_enable(cpu);
1150 static void init_hrtick(void)
1152 hotcpu_notifier(hotplug_hrtick, 0);
1154 #endif /* CONFIG_SMP */
1156 static void init_rq_hrtick(struct rq *rq)
1158 rq->hrtick_flags = 0;
1159 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1160 rq->hrtick_timer.function = hrtick;
1161 rq->hrtick_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ;
1164 void hrtick_resched(void)
1167 unsigned long flags;
1169 if (!test_thread_flag(TIF_HRTICK_RESCHED))
1172 local_irq_save(flags);
1173 rq = cpu_rq(smp_processor_id());
1175 local_irq_restore(flags);
1178 static inline void hrtick_clear(struct rq *rq)
1182 static inline void hrtick_set(struct rq *rq)
1186 static inline void init_rq_hrtick(struct rq *rq)
1190 void hrtick_resched(void)
1194 static inline void init_hrtick(void)
1200 * resched_task - mark a task 'to be rescheduled now'.
1202 * On UP this means the setting of the need_resched flag, on SMP it
1203 * might also involve a cross-CPU call to trigger the scheduler on
1208 #ifndef tsk_is_polling
1209 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1212 static void __resched_task(struct task_struct *p, int tif_bit)
1216 assert_spin_locked(&task_rq(p)->lock);
1218 if (unlikely(test_tsk_thread_flag(p, tif_bit)))
1221 set_tsk_thread_flag(p, tif_bit);
1224 if (cpu == smp_processor_id())
1227 /* NEED_RESCHED must be visible before we test polling */
1229 if (!tsk_is_polling(p))
1230 smp_send_reschedule(cpu);
1233 static void resched_cpu(int cpu)
1235 struct rq *rq = cpu_rq(cpu);
1236 unsigned long flags;
1238 if (!spin_trylock_irqsave(&rq->lock, flags))
1240 resched_task(cpu_curr(cpu));
1241 spin_unlock_irqrestore(&rq->lock, flags);
1246 * When add_timer_on() enqueues a timer into the timer wheel of an
1247 * idle CPU then this timer might expire before the next timer event
1248 * which is scheduled to wake up that CPU. In case of a completely
1249 * idle system the next event might even be infinite time into the
1250 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
1251 * leaves the inner idle loop so the newly added timer is taken into
1252 * account when the CPU goes back to idle and evaluates the timer
1253 * wheel for the next timer event.
1255 void wake_up_idle_cpu(int cpu)
1257 struct rq *rq = cpu_rq(cpu);
1259 if (cpu == smp_processor_id())
1263 * This is safe, as this function is called with the timer
1264 * wheel base lock of (cpu) held. When the CPU is on the way
1265 * to idle and has not yet set rq->curr to idle then it will
1266 * be serialized on the timer wheel base lock and take the new
1267 * timer into account automatically.
1269 if (rq->curr != rq->idle)
1273 * We can set TIF_RESCHED on the idle task of the other CPU
1274 * lockless. The worst case is that the other CPU runs the
1275 * idle task through an additional NOOP schedule()
1277 set_tsk_thread_flag(rq->idle, TIF_NEED_RESCHED);
1279 /* NEED_RESCHED must be visible before we test polling */
1281 if (!tsk_is_polling(rq->idle))
1282 smp_send_reschedule(cpu);
1284 #endif /* CONFIG_NO_HZ */
1286 #else /* !CONFIG_SMP */
1287 static void __resched_task(struct task_struct *p, int tif_bit)
1289 assert_spin_locked(&task_rq(p)->lock);
1290 set_tsk_thread_flag(p, tif_bit);
1292 #endif /* CONFIG_SMP */
1294 #if BITS_PER_LONG == 32
1295 # define WMULT_CONST (~0UL)
1297 # define WMULT_CONST (1UL << 32)
1300 #define WMULT_SHIFT 32
1303 * Shift right and round:
1305 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
1308 * delta *= weight / lw
1310 static unsigned long
1311 calc_delta_mine(unsigned long delta_exec, unsigned long weight,
1312 struct load_weight *lw)
1316 if (!lw->inv_weight) {
1317 if (BITS_PER_LONG > 32 && unlikely(lw->weight >= WMULT_CONST))
1320 lw->inv_weight = 1 + (WMULT_CONST-lw->weight/2)
1324 tmp = (u64)delta_exec * weight;
1326 * Check whether we'd overflow the 64-bit multiplication:
1328 if (unlikely(tmp > WMULT_CONST))
1329 tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
1332 tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
1334 return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
1337 static inline void update_load_add(struct load_weight *lw, unsigned long inc)
1343 static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
1350 * To aid in avoiding the subversion of "niceness" due to uneven distribution
1351 * of tasks with abnormal "nice" values across CPUs the contribution that
1352 * each task makes to its run queue's load is weighted according to its
1353 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
1354 * scaled version of the new time slice allocation that they receive on time
1358 #define WEIGHT_IDLEPRIO 2
1359 #define WMULT_IDLEPRIO (1 << 31)
1362 * Nice levels are multiplicative, with a gentle 10% change for every
1363 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
1364 * nice 1, it will get ~10% less CPU time than another CPU-bound task
1365 * that remained on nice 0.
1367 * The "10% effect" is relative and cumulative: from _any_ nice level,
1368 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
1369 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
1370 * If a task goes up by ~10% and another task goes down by ~10% then
1371 * the relative distance between them is ~25%.)
1373 static const int prio_to_weight[40] = {
1374 /* -20 */ 88761, 71755, 56483, 46273, 36291,
1375 /* -15 */ 29154, 23254, 18705, 14949, 11916,
1376 /* -10 */ 9548, 7620, 6100, 4904, 3906,
1377 /* -5 */ 3121, 2501, 1991, 1586, 1277,
1378 /* 0 */ 1024, 820, 655, 526, 423,
1379 /* 5 */ 335, 272, 215, 172, 137,
1380 /* 10 */ 110, 87, 70, 56, 45,
1381 /* 15 */ 36, 29, 23, 18, 15,
1385 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
1387 * In cases where the weight does not change often, we can use the
1388 * precalculated inverse to speed up arithmetics by turning divisions
1389 * into multiplications:
1391 static const u32 prio_to_wmult[40] = {
1392 /* -20 */ 48388, 59856, 76040, 92818, 118348,
1393 /* -15 */ 147320, 184698, 229616, 287308, 360437,
1394 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
1395 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
1396 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
1397 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
1398 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
1399 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
1402 static void activate_task(struct rq *rq, struct task_struct *p, int wakeup);
1405 * runqueue iterator, to support SMP load-balancing between different
1406 * scheduling classes, without having to expose their internal data
1407 * structures to the load-balancing proper:
1409 struct rq_iterator {
1411 struct task_struct *(*start)(void *);
1412 struct task_struct *(*next)(void *);
1416 static unsigned long
1417 balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
1418 unsigned long max_load_move, struct sched_domain *sd,
1419 enum cpu_idle_type idle, int *all_pinned,
1420 int *this_best_prio, struct rq_iterator *iterator);
1423 iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
1424 struct sched_domain *sd, enum cpu_idle_type idle,
1425 struct rq_iterator *iterator);
1428 #ifdef CONFIG_CGROUP_CPUACCT
1429 static void cpuacct_charge(struct task_struct *tsk, u64 cputime);
1431 static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {}
1434 static inline void inc_cpu_load(struct rq *rq, unsigned long load)
1436 update_load_add(&rq->load, load);
1439 static inline void dec_cpu_load(struct rq *rq, unsigned long load)
1441 update_load_sub(&rq->load, load);
1445 static unsigned long source_load(int cpu, int type);
1446 static unsigned long target_load(int cpu, int type);
1447 static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
1449 static unsigned long cpu_avg_load_per_task(int cpu)
1451 struct rq *rq = cpu_rq(cpu);
1454 rq->avg_load_per_task = rq->load.weight / rq->nr_running;
1456 return rq->avg_load_per_task;
1459 #ifdef CONFIG_FAIR_GROUP_SCHED
1461 typedef void (*tg_visitor)(struct task_group *, int, struct sched_domain *);
1464 * Iterate the full tree, calling @down when first entering a node and @up when
1465 * leaving it for the final time.
1468 walk_tg_tree(tg_visitor down, tg_visitor up, int cpu, struct sched_domain *sd)
1470 struct task_group *parent, *child;
1473 parent = &root_task_group;
1475 (*down)(parent, cpu, sd);
1476 list_for_each_entry_rcu(child, &parent->children, siblings) {
1483 (*up)(parent, cpu, sd);
1486 parent = parent->parent;
1492 static void __set_se_shares(struct sched_entity *se, unsigned long shares);
1495 * Calculate and set the cpu's group shares.
1498 __update_group_shares_cpu(struct task_group *tg, int cpu,
1499 unsigned long sd_shares, unsigned long sd_rq_weight)
1502 unsigned long shares;
1503 unsigned long rq_weight;
1508 rq_weight = tg->cfs_rq[cpu]->load.weight;
1511 * If there are currently no tasks on the cpu pretend there is one of
1512 * average load so that when a new task gets to run here it will not
1513 * get delayed by group starvation.
1517 rq_weight = NICE_0_LOAD;
1520 if (unlikely(rq_weight > sd_rq_weight))
1521 rq_weight = sd_rq_weight;
1524 * \Sum shares * rq_weight
1525 * shares = -----------------------
1529 shares = (sd_shares * rq_weight) / (sd_rq_weight + 1);
1532 * record the actual number of shares, not the boosted amount.
1534 tg->cfs_rq[cpu]->shares = boost ? 0 : shares;
1535 tg->cfs_rq[cpu]->rq_weight = rq_weight;
1537 if (shares < MIN_SHARES)
1538 shares = MIN_SHARES;
1539 else if (shares > MAX_SHARES)
1540 shares = MAX_SHARES;
1542 __set_se_shares(tg->se[cpu], shares);
1546 * Re-compute the task group their per cpu shares over the given domain.
1547 * This needs to be done in a bottom-up fashion because the rq weight of a
1548 * parent group depends on the shares of its child groups.
1551 tg_shares_up(struct task_group *tg, int cpu, struct sched_domain *sd)
1553 unsigned long rq_weight = 0;
1554 unsigned long shares = 0;
1557 for_each_cpu_mask(i, sd->span) {
1558 rq_weight += tg->cfs_rq[i]->load.weight;
1559 shares += tg->cfs_rq[i]->shares;
1562 if ((!shares && rq_weight) || shares > tg->shares)
1563 shares = tg->shares;
1565 if (!sd->parent || !(sd->parent->flags & SD_LOAD_BALANCE))
1566 shares = tg->shares;
1569 rq_weight = cpus_weight(sd->span) * NICE_0_LOAD;
1571 for_each_cpu_mask(i, sd->span) {
1572 struct rq *rq = cpu_rq(i);
1573 unsigned long flags;
1575 spin_lock_irqsave(&rq->lock, flags);
1576 __update_group_shares_cpu(tg, i, shares, rq_weight);
1577 spin_unlock_irqrestore(&rq->lock, flags);
1582 * Compute the cpu's hierarchical load factor for each task group.
1583 * This needs to be done in a top-down fashion because the load of a child
1584 * group is a fraction of its parents load.
1587 tg_load_down(struct task_group *tg, int cpu, struct sched_domain *sd)
1592 load = cpu_rq(cpu)->load.weight;
1594 load = tg->parent->cfs_rq[cpu]->h_load;
1595 load *= tg->cfs_rq[cpu]->shares;
1596 load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
1599 tg->cfs_rq[cpu]->h_load = load;
1603 tg_nop(struct task_group *tg, int cpu, struct sched_domain *sd)
1607 static void update_shares(struct sched_domain *sd)
1609 u64 now = cpu_clock(raw_smp_processor_id());
1610 s64 elapsed = now - sd->last_update;
1612 if (elapsed >= (s64)(u64)sysctl_sched_shares_ratelimit) {
1613 sd->last_update = now;
1614 walk_tg_tree(tg_nop, tg_shares_up, 0, sd);
1618 static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
1620 spin_unlock(&rq->lock);
1622 spin_lock(&rq->lock);
1625 static void update_h_load(int cpu)
1627 walk_tg_tree(tg_load_down, tg_nop, cpu, NULL);
1632 static inline void update_shares(struct sched_domain *sd)
1636 static inline void update_shares_locked(struct rq *rq, struct sched_domain *sd)
1644 #ifdef CONFIG_FAIR_GROUP_SCHED
1645 static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares)
1648 cfs_rq->shares = shares;
1653 #include "sched_stats.h"
1654 #include "sched_idletask.c"
1655 #include "sched_fair.c"
1656 #include "sched_rt.c"
1657 #ifdef CONFIG_SCHED_DEBUG
1658 # include "sched_debug.c"
1661 #define sched_class_highest (&rt_sched_class)
1662 #define for_each_class(class) \
1663 for (class = sched_class_highest; class; class = class->next)
1665 static void inc_nr_running(struct rq *rq)
1670 static void dec_nr_running(struct rq *rq)
1675 static void set_load_weight(struct task_struct *p)
1677 if (task_has_rt_policy(p)) {
1678 p->se.load.weight = prio_to_weight[0] * 2;
1679 p->se.load.inv_weight = prio_to_wmult[0] >> 1;
1684 * SCHED_IDLE tasks get minimal weight:
1686 if (p->policy == SCHED_IDLE) {
1687 p->se.load.weight = WEIGHT_IDLEPRIO;
1688 p->se.load.inv_weight = WMULT_IDLEPRIO;
1692 p->se.load.weight = prio_to_weight[p->static_prio - MAX_RT_PRIO];
1693 p->se.load.inv_weight = prio_to_wmult[p->static_prio - MAX_RT_PRIO];
1696 static void enqueue_task(struct rq *rq, struct task_struct *p, int wakeup)
1698 sched_info_queued(p);
1699 p->sched_class->enqueue_task(rq, p, wakeup);
1703 static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep)
1705 p->sched_class->dequeue_task(rq, p, sleep);
1710 * __normal_prio - return the priority that is based on the static prio
1712 static inline int __normal_prio(struct task_struct *p)
1714 return p->static_prio;
1718 * Calculate the expected normal priority: i.e. priority
1719 * without taking RT-inheritance into account. Might be
1720 * boosted by interactivity modifiers. Changes upon fork,
1721 * setprio syscalls, and whenever the interactivity
1722 * estimator recalculates.
1724 static inline int normal_prio(struct task_struct *p)
1728 if (task_has_rt_policy(p))
1729 prio = MAX_RT_PRIO-1 - p->rt_priority;
1731 prio = __normal_prio(p);
1736 * Calculate the current priority, i.e. the priority
1737 * taken into account by the scheduler. This value might
1738 * be boosted by RT tasks, or might be boosted by
1739 * interactivity modifiers. Will be RT if the task got
1740 * RT-boosted. If not then it returns p->normal_prio.
1742 static int effective_prio(struct task_struct *p)
1744 p->normal_prio = normal_prio(p);
1746 * If we are RT tasks or we were boosted to RT priority,
1747 * keep the priority unchanged. Otherwise, update priority
1748 * to the normal priority:
1750 if (!rt_prio(p->prio))
1751 return p->normal_prio;
1756 * activate_task - move a task to the runqueue.
1758 static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
1760 if (task_contributes_to_load(p))
1761 rq->nr_uninterruptible--;
1763 enqueue_task(rq, p, wakeup);
1768 * deactivate_task - remove a task from the runqueue.
1770 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
1772 if (task_contributes_to_load(p))
1773 rq->nr_uninterruptible++;
1775 dequeue_task(rq, p, sleep);
1780 * task_curr - is this task currently executing on a CPU?
1781 * @p: the task in question.
1783 inline int task_curr(const struct task_struct *p)
1785 return cpu_curr(task_cpu(p)) == p;
1788 static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
1790 set_task_rq(p, cpu);
1793 * After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
1794 * successfuly executed on another CPU. We must ensure that updates of
1795 * per-task data have been completed by this moment.
1798 task_thread_info(p)->cpu = cpu;
1802 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
1803 const struct sched_class *prev_class,
1804 int oldprio, int running)
1806 if (prev_class != p->sched_class) {
1807 if (prev_class->switched_from)
1808 prev_class->switched_from(rq, p, running);
1809 p->sched_class->switched_to(rq, p, running);
1811 p->sched_class->prio_changed(rq, p, oldprio, running);
1816 /* Used instead of source_load when we know the type == 0 */
1817 static unsigned long weighted_cpuload(const int cpu)
1819 return cpu_rq(cpu)->load.weight;
1823 * Is this task likely cache-hot:
1826 task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
1831 * Buddy candidates are cache hot:
1833 if (sched_feat(CACHE_HOT_BUDDY) && (&p->se == cfs_rq_of(&p->se)->next))
1836 if (p->sched_class != &fair_sched_class)
1839 if (sysctl_sched_migration_cost == -1)
1841 if (sysctl_sched_migration_cost == 0)
1844 delta = now - p->se.exec_start;
1846 return delta < (s64)sysctl_sched_migration_cost;
1850 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1852 int old_cpu = task_cpu(p);
1853 struct rq *old_rq = cpu_rq(old_cpu), *new_rq = cpu_rq(new_cpu);
1854 struct cfs_rq *old_cfsrq = task_cfs_rq(p),
1855 *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu);
1858 clock_offset = old_rq->clock - new_rq->clock;
1860 #ifdef CONFIG_SCHEDSTATS
1861 if (p->se.wait_start)
1862 p->se.wait_start -= clock_offset;
1863 if (p->se.sleep_start)
1864 p->se.sleep_start -= clock_offset;
1865 if (p->se.block_start)
1866 p->se.block_start -= clock_offset;
1867 if (old_cpu != new_cpu) {
1868 schedstat_inc(p, se.nr_migrations);
1869 if (task_hot(p, old_rq->clock, NULL))
1870 schedstat_inc(p, se.nr_forced2_migrations);
1873 p->se.vruntime -= old_cfsrq->min_vruntime -
1874 new_cfsrq->min_vruntime;
1876 __set_task_cpu(p, new_cpu);
1879 struct migration_req {
1880 struct list_head list;
1882 struct task_struct *task;
1885 struct completion done;
1889 * The task's runqueue lock must be held.
1890 * Returns true if you have to wait for migration thread.
1893 migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
1895 struct rq *rq = task_rq(p);
1898 * If the task is not on a runqueue (and not running), then
1899 * it is sufficient to simply update the task's cpu field.
1901 if (!p->se.on_rq && !task_running(rq, p)) {
1902 set_task_cpu(p, dest_cpu);
1906 init_completion(&req->done);
1908 req->dest_cpu = dest_cpu;
1909 list_add(&req->list, &rq->migration_queue);
1915 * wait_task_inactive - wait for a thread to unschedule.
1917 * The caller must ensure that the task *will* unschedule sometime soon,
1918 * else this function might spin for a *long* time. This function can't
1919 * be called with interrupts off, or it may introduce deadlock with
1920 * smp_call_function() if an IPI is sent by the same process we are
1921 * waiting to become inactive.
1923 void wait_task_inactive(struct task_struct *p)
1925 unsigned long flags;
1931 * We do the initial early heuristics without holding
1932 * any task-queue locks at all. We'll only try to get
1933 * the runqueue lock when things look like they will
1939 * If the task is actively running on another CPU
1940 * still, just relax and busy-wait without holding
1943 * NOTE! Since we don't hold any locks, it's not
1944 * even sure that "rq" stays as the right runqueue!
1945 * But we don't care, since "task_running()" will
1946 * return false if the runqueue has changed and p
1947 * is actually now running somewhere else!
1949 while (task_running(rq, p))
1953 * Ok, time to look more closely! We need the rq
1954 * lock now, to be *sure*. If we're wrong, we'll
1955 * just go back and repeat.
1957 rq = task_rq_lock(p, &flags);
1958 running = task_running(rq, p);
1959 on_rq = p->se.on_rq;
1960 task_rq_unlock(rq, &flags);
1963 * Was it really running after all now that we
1964 * checked with the proper locks actually held?
1966 * Oops. Go back and try again..
1968 if (unlikely(running)) {
1974 * It's not enough that it's not actively running,
1975 * it must be off the runqueue _entirely_, and not
1978 * So if it wa still runnable (but just not actively
1979 * running right now), it's preempted, and we should
1980 * yield - it could be a while.
1982 if (unlikely(on_rq)) {
1983 schedule_timeout_uninterruptible(1);
1988 * Ahh, all good. It wasn't running, and it wasn't
1989 * runnable, which means that it will never become
1990 * running in the future either. We're all done!
1997 * kick_process - kick a running thread to enter/exit the kernel
1998 * @p: the to-be-kicked thread
2000 * Cause a process which is running on another CPU to enter
2001 * kernel-mode, without any delay. (to get signals handled.)
2003 * NOTE: this function doesnt have to take the runqueue lock,
2004 * because all it wants to ensure is that the remote task enters
2005 * the kernel. If the IPI races and the task has been migrated
2006 * to another CPU then no harm is done and the purpose has been
2009 void kick_process(struct task_struct *p)
2015 if ((cpu != smp_processor_id()) && task_curr(p))
2016 smp_send_reschedule(cpu);
2021 * Return a low guess at the load of a migration-source cpu weighted
2022 * according to the scheduling class and "nice" value.
2024 * We want to under-estimate the load of migration sources, to
2025 * balance conservatively.
2027 static unsigned long source_load(int cpu, int type)
2029 struct rq *rq = cpu_rq(cpu);
2030 unsigned long total = weighted_cpuload(cpu);
2032 if (type == 0 || !sched_feat(LB_BIAS))
2035 return min(rq->cpu_load[type-1], total);
2039 * Return a high guess at the load of a migration-target cpu weighted
2040 * according to the scheduling class and "nice" value.
2042 static unsigned long target_load(int cpu, int type)
2044 struct rq *rq = cpu_rq(cpu);
2045 unsigned long total = weighted_cpuload(cpu);
2047 if (type == 0 || !sched_feat(LB_BIAS))
2050 return max(rq->cpu_load[type-1], total);
2054 * find_idlest_group finds and returns the least busy CPU group within the
2057 static struct sched_group *
2058 find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
2060 struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
2061 unsigned long min_load = ULONG_MAX, this_load = 0;
2062 int load_idx = sd->forkexec_idx;
2063 int imbalance = 100 + (sd->imbalance_pct-100)/2;
2066 unsigned long load, avg_load;
2070 /* Skip over this group if it has no CPUs allowed */
2071 if (!cpus_intersects(group->cpumask, p->cpus_allowed))
2074 local_group = cpu_isset(this_cpu, group->cpumask);
2076 /* Tally up the load of all CPUs in the group */
2079 for_each_cpu_mask(i, group->cpumask) {
2080 /* Bias balancing toward cpus of our domain */
2082 load = source_load(i, load_idx);
2084 load = target_load(i, load_idx);
2089 /* Adjust by relative CPU power of the group */
2090 avg_load = sg_div_cpu_power(group,
2091 avg_load * SCHED_LOAD_SCALE);
2094 this_load = avg_load;
2096 } else if (avg_load < min_load) {
2097 min_load = avg_load;
2100 } while (group = group->next, group != sd->groups);
2102 if (!idlest || 100*this_load < imbalance*min_load)
2108 * find_idlest_cpu - find the idlest cpu among the cpus in group.
2111 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu,
2114 unsigned long load, min_load = ULONG_MAX;
2118 /* Traverse only the allowed CPUs */
2119 cpus_and(*tmp, group->cpumask, p->cpus_allowed);
2121 for_each_cpu_mask(i, *tmp) {
2122 load = weighted_cpuload(i);
2124 if (load < min_load || (load == min_load && i == this_cpu)) {
2134 * sched_balance_self: balance the current task (running on cpu) in domains
2135 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
2138 * Balance, ie. select the least loaded group.
2140 * Returns the target CPU number, or the same CPU if no balancing is needed.
2142 * preempt must be disabled.
2144 static int sched_balance_self(int cpu, int flag)
2146 struct task_struct *t = current;
2147 struct sched_domain *tmp, *sd = NULL;
2149 for_each_domain(cpu, tmp) {
2151 * If power savings logic is enabled for a domain, stop there.
2153 if (tmp->flags & SD_POWERSAVINGS_BALANCE)
2155 if (tmp->flags & flag)
2163 cpumask_t span, tmpmask;
2164 struct sched_group *group;
2165 int new_cpu, weight;
2167 if (!(sd->flags & flag)) {
2173 group = find_idlest_group(sd, t, cpu);
2179 new_cpu = find_idlest_cpu(group, t, cpu, &tmpmask);
2180 if (new_cpu == -1 || new_cpu == cpu) {
2181 /* Now try balancing at a lower domain level of cpu */
2186 /* Now try balancing at a lower domain level of new_cpu */
2189 weight = cpus_weight(span);
2190 for_each_domain(cpu, tmp) {
2191 if (weight <= cpus_weight(tmp->span))
2193 if (tmp->flags & flag)
2196 /* while loop will break here if sd == NULL */
2202 #endif /* CONFIG_SMP */
2205 * try_to_wake_up - wake up a thread
2206 * @p: the to-be-woken-up thread
2207 * @state: the mask of task states that can be woken
2208 * @sync: do a synchronous wakeup?
2210 * Put it on the run-queue if it's not already there. The "current"
2211 * thread is always on the run-queue (except when the actual
2212 * re-schedule is in progress), and as such you're allowed to do
2213 * the simpler "current->state = TASK_RUNNING" to mark yourself
2214 * runnable without the overhead of this.
2216 * returns failure only if the task is already active.
2218 static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
2220 int cpu, orig_cpu, this_cpu, success = 0;
2221 unsigned long flags;
2225 if (!sched_feat(SYNC_WAKEUPS))
2229 if (sched_feat(LB_WAKEUP_UPDATE)) {
2230 struct sched_domain *sd;
2232 this_cpu = raw_smp_processor_id();
2235 for_each_domain(this_cpu, sd) {
2236 if (cpu_isset(cpu, sd->span)) {
2245 rq = task_rq_lock(p, &flags);
2246 old_state = p->state;
2247 if (!(old_state & state))
2255 this_cpu = smp_processor_id();
2258 if (unlikely(task_running(rq, p)))
2261 cpu = p->sched_class->select_task_rq(p, sync);
2262 if (cpu != orig_cpu) {
2263 set_task_cpu(p, cpu);
2264 task_rq_unlock(rq, &flags);
2265 /* might preempt at this point */
2266 rq = task_rq_lock(p, &flags);
2267 old_state = p->state;
2268 if (!(old_state & state))
2273 this_cpu = smp_processor_id();
2277 #ifdef CONFIG_SCHEDSTATS
2278 schedstat_inc(rq, ttwu_count);
2279 if (cpu == this_cpu)
2280 schedstat_inc(rq, ttwu_local);
2282 struct sched_domain *sd;
2283 for_each_domain(this_cpu, sd) {
2284 if (cpu_isset(cpu, sd->span)) {
2285 schedstat_inc(sd, ttwu_wake_remote);
2290 #endif /* CONFIG_SCHEDSTATS */
2293 #endif /* CONFIG_SMP */
2294 schedstat_inc(p, se.nr_wakeups);
2296 schedstat_inc(p, se.nr_wakeups_sync);
2297 if (orig_cpu != cpu)
2298 schedstat_inc(p, se.nr_wakeups_migrate);
2299 if (cpu == this_cpu)
2300 schedstat_inc(p, se.nr_wakeups_local);
2302 schedstat_inc(p, se.nr_wakeups_remote);
2303 update_rq_clock(rq);
2304 activate_task(rq, p, 1);
2308 check_preempt_curr(rq, p);
2310 p->state = TASK_RUNNING;
2312 if (p->sched_class->task_wake_up)
2313 p->sched_class->task_wake_up(rq, p);
2316 task_rq_unlock(rq, &flags);
2321 int wake_up_process(struct task_struct *p)
2323 return try_to_wake_up(p, TASK_ALL, 0);
2325 EXPORT_SYMBOL(wake_up_process);
2327 int wake_up_state(struct task_struct *p, unsigned int state)
2329 return try_to_wake_up(p, state, 0);
2333 * Perform scheduler related setup for a newly forked process p.
2334 * p is forked by current.
2336 * __sched_fork() is basic setup used by init_idle() too:
2338 static void __sched_fork(struct task_struct *p)
2340 p->se.exec_start = 0;
2341 p->se.sum_exec_runtime = 0;
2342 p->se.prev_sum_exec_runtime = 0;
2343 p->se.last_wakeup = 0;
2344 p->se.avg_overlap = 0;
2346 #ifdef CONFIG_SCHEDSTATS
2347 p->se.wait_start = 0;
2348 p->se.sum_sleep_runtime = 0;
2349 p->se.sleep_start = 0;
2350 p->se.block_start = 0;
2351 p->se.sleep_max = 0;
2352 p->se.block_max = 0;
2354 p->se.slice_max = 0;
2358 INIT_LIST_HEAD(&p->rt.run_list);
2360 INIT_LIST_HEAD(&p->se.group_node);
2362 #ifdef CONFIG_PREEMPT_NOTIFIERS
2363 INIT_HLIST_HEAD(&p->preempt_notifiers);
2367 * We mark the process as running here, but have not actually
2368 * inserted it onto the runqueue yet. This guarantees that
2369 * nobody will actually run it, and a signal or other external
2370 * event cannot wake it up and insert it on the runqueue either.
2372 p->state = TASK_RUNNING;
2376 * fork()/clone()-time setup:
2378 void sched_fork(struct task_struct *p, int clone_flags)
2380 int cpu = get_cpu();
2385 cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
2387 set_task_cpu(p, cpu);
2390 * Make sure we do not leak PI boosting priority to the child:
2392 p->prio = current->normal_prio;
2393 if (!rt_prio(p->prio))
2394 p->sched_class = &fair_sched_class;
2396 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
2397 if (likely(sched_info_on()))
2398 memset(&p->sched_info, 0, sizeof(p->sched_info));
2400 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
2403 #ifdef CONFIG_PREEMPT
2404 /* Want to start with kernel preemption disabled. */
2405 task_thread_info(p)->preempt_count = 1;
2411 * wake_up_new_task - wake up a newly created task for the first time.
2413 * This function will do some initial scheduler statistics housekeeping
2414 * that must be done for every newly created context, then puts the task
2415 * on the runqueue and wakes it.
2417 void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
2419 unsigned long flags;
2422 rq = task_rq_lock(p, &flags);
2423 BUG_ON(p->state != TASK_RUNNING);
2424 update_rq_clock(rq);
2426 p->prio = effective_prio(p);
2428 if (!p->sched_class->task_new || !current->se.on_rq) {
2429 activate_task(rq, p, 0);
2432 * Let the scheduling class do new task startup
2433 * management (if any):
2435 p->sched_class->task_new(rq, p);
2438 check_preempt_curr(rq, p);
2440 if (p->sched_class->task_wake_up)
2441 p->sched_class->task_wake_up(rq, p);
2443 task_rq_unlock(rq, &flags);
2446 #ifdef CONFIG_PREEMPT_NOTIFIERS
2449 * preempt_notifier_register - tell me when current is being being preempted & rescheduled
2450 * @notifier: notifier struct to register
2452 void preempt_notifier_register(struct preempt_notifier *notifier)
2454 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2456 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2459 * preempt_notifier_unregister - no longer interested in preemption notifications
2460 * @notifier: notifier struct to unregister
2462 * This is safe to call from within a preemption notifier.
2464 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2466 hlist_del(¬ifier->link);
2468 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2470 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2472 struct preempt_notifier *notifier;
2473 struct hlist_node *node;
2475 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2476 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2480 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2481 struct task_struct *next)
2483 struct preempt_notifier *notifier;
2484 struct hlist_node *node;
2486 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2487 notifier->ops->sched_out(notifier, next);
2490 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2492 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2497 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2498 struct task_struct *next)
2502 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2505 * prepare_task_switch - prepare to switch tasks
2506 * @rq: the runqueue preparing to switch
2507 * @prev: the current task that is being switched out
2508 * @next: the task we are going to switch to.
2510 * This is called with the rq lock held and interrupts off. It must
2511 * be paired with a subsequent finish_task_switch after the context
2514 * prepare_task_switch sets up locking and calls architecture specific
2518 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2519 struct task_struct *next)
2521 fire_sched_out_preempt_notifiers(prev, next);
2522 prepare_lock_switch(rq, next);
2523 prepare_arch_switch(next);
2527 * finish_task_switch - clean up after a task-switch
2528 * @rq: runqueue associated with task-switch
2529 * @prev: the thread we just switched away from.
2531 * finish_task_switch must be called after the context switch, paired
2532 * with a prepare_task_switch call before the context switch.
2533 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2534 * and do any other architecture-specific cleanup actions.
2536 * Note that we may have delayed dropping an mm in context_switch(). If
2537 * so, we finish that here outside of the runqueue lock. (Doing it
2538 * with the lock held can cause deadlocks; see schedule() for
2541 static void finish_task_switch(struct rq *rq, struct task_struct *prev)
2542 __releases(rq->lock)
2544 struct mm_struct *mm = rq->prev_mm;
2550 * A task struct has one reference for the use as "current".
2551 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2552 * schedule one last time. The schedule call will never return, and
2553 * the scheduled task must drop that reference.
2554 * The test for TASK_DEAD must occur while the runqueue locks are
2555 * still held, otherwise prev could be scheduled on another cpu, die
2556 * there before we look at prev->state, and then the reference would
2558 * Manfred Spraul <manfred@colorfullife.com>
2560 prev_state = prev->state;
2561 finish_arch_switch(prev);
2562 finish_lock_switch(rq, prev);
2564 if (current->sched_class->post_schedule)
2565 current->sched_class->post_schedule(rq);
2568 fire_sched_in_preempt_notifiers(current);
2571 if (unlikely(prev_state == TASK_DEAD)) {
2573 * Remove function-return probe instances associated with this
2574 * task and put them back on the free list.
2576 kprobe_flush_task(prev);
2577 put_task_struct(prev);
2582 * schedule_tail - first thing a freshly forked thread must call.
2583 * @prev: the thread we just switched away from.
2585 asmlinkage void schedule_tail(struct task_struct *prev)
2586 __releases(rq->lock)
2588 struct rq *rq = this_rq();
2590 finish_task_switch(rq, prev);
2591 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2592 /* In this case, finish_task_switch does not reenable preemption */
2595 if (current->set_child_tid)
2596 put_user(task_pid_vnr(current), current->set_child_tid);
2600 * context_switch - switch to the new MM and the new
2601 * thread's register state.
2604 context_switch(struct rq *rq, struct task_struct *prev,
2605 struct task_struct *next)
2607 struct mm_struct *mm, *oldmm;
2609 prepare_task_switch(rq, prev, next);
2611 oldmm = prev->active_mm;
2613 * For paravirt, this is coupled with an exit in switch_to to
2614 * combine the page table reload and the switch backend into
2617 arch_enter_lazy_cpu_mode();
2619 if (unlikely(!mm)) {
2620 next->active_mm = oldmm;
2621 atomic_inc(&oldmm->mm_count);
2622 enter_lazy_tlb(oldmm, next);
2624 switch_mm(oldmm, mm, next);
2626 if (unlikely(!prev->mm)) {
2627 prev->active_mm = NULL;
2628 rq->prev_mm = oldmm;
2631 * Since the runqueue lock will be released by the next
2632 * task (which is an invalid locking op but in the case
2633 * of the scheduler it's an obvious special-case), so we
2634 * do an early lockdep release here:
2636 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2637 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2640 /* Here we just switch the register state and the stack. */
2641 switch_to(prev, next, prev);
2645 * this_rq must be evaluated again because prev may have moved
2646 * CPUs since it called schedule(), thus the 'rq' on its stack
2647 * frame will be invalid.
2649 finish_task_switch(this_rq(), prev);
2653 * nr_running, nr_uninterruptible and nr_context_switches:
2655 * externally visible scheduler statistics: current number of runnable
2656 * threads, current number of uninterruptible-sleeping threads, total
2657 * number of context switches performed since bootup.
2659 unsigned long nr_running(void)
2661 unsigned long i, sum = 0;
2663 for_each_online_cpu(i)
2664 sum += cpu_rq(i)->nr_running;
2669 unsigned long nr_uninterruptible(void)
2671 unsigned long i, sum = 0;
2673 for_each_possible_cpu(i)
2674 sum += cpu_rq(i)->nr_uninterruptible;
2677 * Since we read the counters lockless, it might be slightly
2678 * inaccurate. Do not allow it to go below zero though:
2680 if (unlikely((long)sum < 0))
2686 unsigned long long nr_context_switches(void)
2689 unsigned long long sum = 0;
2691 for_each_possible_cpu(i)
2692 sum += cpu_rq(i)->nr_switches;
2697 unsigned long nr_iowait(void)
2699 unsigned long i, sum = 0;
2701 for_each_possible_cpu(i)
2702 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2707 unsigned long nr_active(void)
2709 unsigned long i, running = 0, uninterruptible = 0;
2711 for_each_online_cpu(i) {
2712 running += cpu_rq(i)->nr_running;
2713 uninterruptible += cpu_rq(i)->nr_uninterruptible;
2716 if (unlikely((long)uninterruptible < 0))
2717 uninterruptible = 0;
2719 return running + uninterruptible;
2723 * Update rq->cpu_load[] statistics. This function is usually called every
2724 * scheduler tick (TICK_NSEC).
2726 static void update_cpu_load(struct rq *this_rq)
2728 unsigned long this_load = this_rq->load.weight;
2731 this_rq->nr_load_updates++;
2733 /* Update our load: */
2734 for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
2735 unsigned long old_load, new_load;
2737 /* scale is effectively 1 << i now, and >> i divides by scale */
2739 old_load = this_rq->cpu_load[i];
2740 new_load = this_load;
2742 * Round up the averaging division if load is increasing. This
2743 * prevents us from getting stuck on 9 if the load is 10, for
2746 if (new_load > old_load)
2747 new_load += scale-1;
2748 this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
2755 * double_rq_lock - safely lock two runqueues
2757 * Note this does not disable interrupts like task_rq_lock,
2758 * you need to do so manually before calling.
2760 static void double_rq_lock(struct rq *rq1, struct rq *rq2)
2761 __acquires(rq1->lock)
2762 __acquires(rq2->lock)
2764 BUG_ON(!irqs_disabled());
2766 spin_lock(&rq1->lock);
2767 __acquire(rq2->lock); /* Fake it out ;) */
2770 spin_lock(&rq1->lock);
2771 spin_lock(&rq2->lock);
2773 spin_lock(&rq2->lock);
2774 spin_lock(&rq1->lock);
2777 update_rq_clock(rq1);
2778 update_rq_clock(rq2);
2782 * double_rq_unlock - safely unlock two runqueues
2784 * Note this does not restore interrupts like task_rq_unlock,
2785 * you need to do so manually after calling.
2787 static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
2788 __releases(rq1->lock)
2789 __releases(rq2->lock)
2791 spin_unlock(&rq1->lock);
2793 spin_unlock(&rq2->lock);
2795 __release(rq2->lock);
2799 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2801 static int double_lock_balance(struct rq *this_rq, struct rq *busiest)
2802 __releases(this_rq->lock)
2803 __acquires(busiest->lock)
2804 __acquires(this_rq->lock)
2808 if (unlikely(!irqs_disabled())) {
2809 /* printk() doesn't work good under rq->lock */
2810 spin_unlock(&this_rq->lock);
2813 if (unlikely(!spin_trylock(&busiest->lock))) {
2814 if (busiest < this_rq) {
2815 spin_unlock(&this_rq->lock);
2816 spin_lock(&busiest->lock);
2817 spin_lock(&this_rq->lock);
2820 spin_lock(&busiest->lock);
2826 * If dest_cpu is allowed for this process, migrate the task to it.
2827 * This is accomplished by forcing the cpu_allowed mask to only
2828 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2829 * the cpu_allowed mask is restored.
2831 static void sched_migrate_task(struct task_struct *p, int dest_cpu)
2833 struct migration_req req;
2834 unsigned long flags;
2837 rq = task_rq_lock(p, &flags);
2838 if (!cpu_isset(dest_cpu, p->cpus_allowed)
2839 || unlikely(cpu_is_offline(dest_cpu)))
2842 /* force the process onto the specified CPU */
2843 if (migrate_task(p, dest_cpu, &req)) {
2844 /* Need to wait for migration thread (might exit: take ref). */
2845 struct task_struct *mt = rq->migration_thread;
2847 get_task_struct(mt);
2848 task_rq_unlock(rq, &flags);
2849 wake_up_process(mt);
2850 put_task_struct(mt);
2851 wait_for_completion(&req.done);
2856 task_rq_unlock(rq, &flags);
2860 * sched_exec - execve() is a valuable balancing opportunity, because at
2861 * this point the task has the smallest effective memory and cache footprint.
2863 void sched_exec(void)
2865 int new_cpu, this_cpu = get_cpu();
2866 new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
2868 if (new_cpu != this_cpu)
2869 sched_migrate_task(current, new_cpu);
2873 * pull_task - move a task from a remote runqueue to the local runqueue.
2874 * Both runqueues must be locked.
2876 static void pull_task(struct rq *src_rq, struct task_struct *p,
2877 struct rq *this_rq, int this_cpu)
2879 deactivate_task(src_rq, p, 0);
2880 set_task_cpu(p, this_cpu);
2881 activate_task(this_rq, p, 0);
2883 * Note that idle threads have a prio of MAX_PRIO, for this test
2884 * to be always true for them.
2886 check_preempt_curr(this_rq, p);
2890 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2893 int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
2894 struct sched_domain *sd, enum cpu_idle_type idle,
2898 * We do not migrate tasks that are:
2899 * 1) running (obviously), or
2900 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2901 * 3) are cache-hot on their current CPU.
2903 if (!cpu_isset(this_cpu, p->cpus_allowed)) {
2904 schedstat_inc(p, se.nr_failed_migrations_affine);
2909 if (task_running(rq, p)) {
2910 schedstat_inc(p, se.nr_failed_migrations_running);
2915 * Aggressive migration if:
2916 * 1) task is cache cold, or
2917 * 2) too many balance attempts have failed.
2920 if (!task_hot(p, rq->clock, sd) ||
2921 sd->nr_balance_failed > sd->cache_nice_tries) {
2922 #ifdef CONFIG_SCHEDSTATS
2923 if (task_hot(p, rq->clock, sd)) {
2924 schedstat_inc(sd, lb_hot_gained[idle]);
2925 schedstat_inc(p, se.nr_forced_migrations);
2931 if (task_hot(p, rq->clock, sd)) {
2932 schedstat_inc(p, se.nr_failed_migrations_hot);
2938 static unsigned long
2939 balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2940 unsigned long max_load_move, struct sched_domain *sd,
2941 enum cpu_idle_type idle, int *all_pinned,
2942 int *this_best_prio, struct rq_iterator *iterator)
2944 int loops = 0, pulled = 0, pinned = 0;
2945 struct task_struct *p;
2946 long rem_load_move = max_load_move;
2948 if (max_load_move == 0)
2954 * Start the load-balancing iterator:
2956 p = iterator->start(iterator->arg);
2958 if (!p || loops++ > sysctl_sched_nr_migrate)
2961 if ((p->se.load.weight >> 1) > rem_load_move ||
2962 !can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
2963 p = iterator->next(iterator->arg);
2967 pull_task(busiest, p, this_rq, this_cpu);
2969 rem_load_move -= p->se.load.weight;
2972 * We only want to steal up to the prescribed amount of weighted load.
2974 if (rem_load_move > 0) {
2975 if (p->prio < *this_best_prio)
2976 *this_best_prio = p->prio;
2977 p = iterator->next(iterator->arg);
2982 * Right now, this is one of only two places pull_task() is called,
2983 * so we can safely collect pull_task() stats here rather than
2984 * inside pull_task().
2986 schedstat_add(sd, lb_gained[idle], pulled);
2989 *all_pinned = pinned;
2991 return max_load_move - rem_load_move;
2995 * move_tasks tries to move up to max_load_move weighted load from busiest to
2996 * this_rq, as part of a balancing operation within domain "sd".
2997 * Returns 1 if successful and 0 otherwise.
2999 * Called with both runqueues locked.
3001 static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
3002 unsigned long max_load_move,
3003 struct sched_domain *sd, enum cpu_idle_type idle,
3006 const struct sched_class *class = sched_class_highest;
3007 unsigned long total_load_moved = 0;
3008 int this_best_prio = this_rq->curr->prio;
3012 class->load_balance(this_rq, this_cpu, busiest,
3013 max_load_move - total_load_moved,
3014 sd, idle, all_pinned, &this_best_prio);
3015 class = class->next;
3016 } while (class && max_load_move > total_load_moved);
3018 return total_load_moved > 0;
3022 iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
3023 struct sched_domain *sd, enum cpu_idle_type idle,
3024 struct rq_iterator *iterator)
3026 struct task_struct *p = iterator->start(iterator->arg);
3030 if (can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
3031 pull_task(busiest, p, this_rq, this_cpu);
3033 * Right now, this is only the second place pull_task()
3034 * is called, so we can safely collect pull_task()
3035 * stats here rather than inside pull_task().
3037 schedstat_inc(sd, lb_gained[idle]);
3041 p = iterator->next(iterator->arg);
3048 * move_one_task tries to move exactly one task from busiest to this_rq, as
3049 * part of active balancing operations within "domain".
3050 * Returns 1 if successful and 0 otherwise.
3052 * Called with both runqueues locked.
3054 static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
3055 struct sched_domain *sd, enum cpu_idle_type idle)
3057 const struct sched_class *class;
3059 for (class = sched_class_highest; class; class = class->next)
3060 if (class->move_one_task(this_rq, this_cpu, busiest, sd, idle))
3067 * find_busiest_group finds and returns the busiest CPU group within the
3068 * domain. It calculates and returns the amount of weighted load which
3069 * should be moved to restore balance via the imbalance parameter.
3071 static struct sched_group *
3072 find_busiest_group(struct sched_domain *sd, int this_cpu,
3073 unsigned long *imbalance, enum cpu_idle_type idle,
3074 int *sd_idle, const cpumask_t *cpus, int *balance)
3076 struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
3077 unsigned long max_load, avg_load, total_load, this_load, total_pwr;
3078 unsigned long max_pull;
3079 unsigned long busiest_load_per_task, busiest_nr_running;
3080 unsigned long this_load_per_task, this_nr_running;
3081 int load_idx, group_imb = 0;
3082 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
3083 int power_savings_balance = 1;
3084 unsigned long leader_nr_running = 0, min_load_per_task = 0;
3085 unsigned long min_nr_running = ULONG_MAX;
3086 struct sched_group *group_min = NULL, *group_leader = NULL;
3089 max_load = this_load = total_load = total_pwr = 0;
3090 busiest_load_per_task = busiest_nr_running = 0;
3091 this_load_per_task = this_nr_running = 0;
3093 if (idle == CPU_NOT_IDLE)
3094 load_idx = sd->busy_idx;
3095 else if (idle == CPU_NEWLY_IDLE)
3096 load_idx = sd->newidle_idx;
3098 load_idx = sd->idle_idx;
3101 unsigned long load, group_capacity, max_cpu_load, min_cpu_load;
3104 int __group_imb = 0;
3105 unsigned int balance_cpu = -1, first_idle_cpu = 0;
3106 unsigned long sum_nr_running, sum_weighted_load;
3107 unsigned long sum_avg_load_per_task;
3108 unsigned long avg_load_per_task;
3110 local_group = cpu_isset(this_cpu, group->cpumask);
3113 balance_cpu = first_cpu(group->cpumask);
3115 /* Tally up the load of all CPUs in the group */
3116 sum_weighted_load = sum_nr_running = avg_load = 0;
3117 sum_avg_load_per_task = avg_load_per_task = 0;
3120 min_cpu_load = ~0UL;
3122 for_each_cpu_mask(i, group->cpumask) {
3125 if (!cpu_isset(i, *cpus))
3130 if (*sd_idle && rq->nr_running)
3133 /* Bias balancing toward cpus of our domain */
3135 if (idle_cpu(i) && !first_idle_cpu) {
3140 load = target_load(i, load_idx);
3142 load = source_load(i, load_idx);
3143 if (load > max_cpu_load)
3144 max_cpu_load = load;
3145 if (min_cpu_load > load)
3146 min_cpu_load = load;
3150 sum_nr_running += rq->nr_running;
3151 sum_weighted_load += weighted_cpuload(i);
3153 sum_avg_load_per_task += cpu_avg_load_per_task(i);
3157 * First idle cpu or the first cpu(busiest) in this sched group
3158 * is eligible for doing load balancing at this and above
3159 * domains. In the newly idle case, we will allow all the cpu's
3160 * to do the newly idle load balance.
3162 if (idle != CPU_NEWLY_IDLE && local_group &&
3163 balance_cpu != this_cpu && balance) {
3168 total_load += avg_load;
3169 total_pwr += group->__cpu_power;
3171 /* Adjust by relative CPU power of the group */
3172 avg_load = sg_div_cpu_power(group,
3173 avg_load * SCHED_LOAD_SCALE);
3177 * Consider the group unbalanced when the imbalance is larger
3178 * than the average weight of two tasks.
3180 * APZ: with cgroup the avg task weight can vary wildly and
3181 * might not be a suitable number - should we keep a
3182 * normalized nr_running number somewhere that negates
3185 avg_load_per_task = sg_div_cpu_power(group,
3186 sum_avg_load_per_task * SCHED_LOAD_SCALE);
3188 if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task)
3191 group_capacity = group->__cpu_power / SCHED_LOAD_SCALE;
3194 this_load = avg_load;
3196 this_nr_running = sum_nr_running;
3197 this_load_per_task = sum_weighted_load;
3198 } else if (avg_load > max_load &&
3199 (sum_nr_running > group_capacity || __group_imb)) {
3200 max_load = avg_load;
3202 busiest_nr_running = sum_nr_running;
3203 busiest_load_per_task = sum_weighted_load;
3204 group_imb = __group_imb;
3207 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
3209 * Busy processors will not participate in power savings
3212 if (idle == CPU_NOT_IDLE ||
3213 !(sd->flags & SD_POWERSAVINGS_BALANCE))
3217 * If the local group is idle or completely loaded
3218 * no need to do power savings balance at this domain
3220 if (local_group && (this_nr_running >= group_capacity ||
3222 power_savings_balance = 0;
3225 * If a group is already running at full capacity or idle,
3226 * don't include that group in power savings calculations
3228 if (!power_savings_balance || sum_nr_running >= group_capacity
3233 * Calculate the group which has the least non-idle load.
3234 * This is the group from where we need to pick up the load
3237 if ((sum_nr_running < min_nr_running) ||
3238 (sum_nr_running == min_nr_running &&
3239 first_cpu(group->cpumask) <
3240 first_cpu(group_min->cpumask))) {
3242 min_nr_running = sum_nr_running;
3243 min_load_per_task = sum_weighted_load /
3248 * Calculate the group which is almost near its
3249 * capacity but still has some space to pick up some load
3250 * from other group and save more power
3252 if (sum_nr_running <= group_capacity - 1) {
3253 if (sum_nr_running > leader_nr_running ||
3254 (sum_nr_running == leader_nr_running &&
3255 first_cpu(group->cpumask) >
3256 first_cpu(group_leader->cpumask))) {
3257 group_leader = group;
3258 leader_nr_running = sum_nr_running;
3263 group = group->next;
3264 } while (group != sd->groups);
3266 if (!busiest || this_load >= max_load || busiest_nr_running == 0)
3269 avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
3271 if (this_load >= avg_load ||
3272 100*max_load <= sd->imbalance_pct*this_load)
3275 busiest_load_per_task /= busiest_nr_running;
3277 busiest_load_per_task = min(busiest_load_per_task, avg_load);
3280 * We're trying to get all the cpus to the average_load, so we don't
3281 * want to push ourselves above the average load, nor do we wish to
3282 * reduce the max loaded cpu below the average load, as either of these
3283 * actions would just result in more rebalancing later, and ping-pong
3284 * tasks around. Thus we look for the minimum possible imbalance.
3285 * Negative imbalances (*we* are more loaded than anyone else) will
3286 * be counted as no imbalance for these purposes -- we can't fix that
3287 * by pulling tasks to us. Be careful of negative numbers as they'll
3288 * appear as very large values with unsigned longs.
3290 if (max_load <= busiest_load_per_task)
3294 * In the presence of smp nice balancing, certain scenarios can have
3295 * max load less than avg load(as we skip the groups at or below
3296 * its cpu_power, while calculating max_load..)
3298 if (max_load < avg_load) {
3300 goto small_imbalance;
3303 /* Don't want to pull so many tasks that a group would go idle */
3304 max_pull = min(max_load - avg_load, max_load - busiest_load_per_task);
3306 /* How much load to actually move to equalise the imbalance */
3307 *imbalance = min(max_pull * busiest->__cpu_power,
3308 (avg_load - this_load) * this->__cpu_power)
3312 * if *imbalance is less than the average load per runnable task
3313 * there is no gaurantee that any tasks will be moved so we'll have
3314 * a think about bumping its value to force at least one task to be
3317 if (*imbalance < busiest_load_per_task) {
3318 unsigned long tmp, pwr_now, pwr_move;
3322 pwr_move = pwr_now = 0;
3324 if (this_nr_running) {
3325 this_load_per_task /= this_nr_running;
3326 if (busiest_load_per_task > this_load_per_task)
3329 this_load_per_task = cpu_avg_load_per_task(this_cpu);
3331 if (max_load - this_load + 2*busiest_load_per_task >=
3332 busiest_load_per_task * imbn) {
3333 *imbalance = busiest_load_per_task;
3338 * OK, we don't have enough imbalance to justify moving tasks,
3339 * however we may be able to increase total CPU power used by
3343 pwr_now += busiest->__cpu_power *
3344 min(busiest_load_per_task, max_load);
3345 pwr_now += this->__cpu_power *
3346 min(this_load_per_task, this_load);
3347 pwr_now /= SCHED_LOAD_SCALE;
3349 /* Amount of load we'd subtract */
3350 tmp = sg_div_cpu_power(busiest,
3351 busiest_load_per_task * SCHED_LOAD_SCALE);
3353 pwr_move += busiest->__cpu_power *
3354 min(busiest_load_per_task, max_load - tmp);
3356 /* Amount of load we'd add */
3357 if (max_load * busiest->__cpu_power <
3358 busiest_load_per_task * SCHED_LOAD_SCALE)
3359 tmp = sg_div_cpu_power(this,
3360 max_load * busiest->__cpu_power);
3362 tmp = sg_div_cpu_power(this,
3363 busiest_load_per_task * SCHED_LOAD_SCALE);
3364 pwr_move += this->__cpu_power *
3365 min(this_load_per_task, this_load + tmp);
3366 pwr_move /= SCHED_LOAD_SCALE;
3368 /* Move if we gain throughput */
3369 if (pwr_move > pwr_now)
3370 *imbalance = busiest_load_per_task;
3376 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
3377 if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
3380 if (this == group_leader && group_leader != group_min) {
3381 *imbalance = min_load_per_task;
3391 * find_busiest_queue - find the busiest runqueue among the cpus in group.
3394 find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
3395 unsigned long imbalance, const cpumask_t *cpus)
3397 struct rq *busiest = NULL, *rq;
3398 unsigned long max_load = 0;
3401 for_each_cpu_mask(i, group->cpumask) {
3404 if (!cpu_isset(i, *cpus))
3408 wl = weighted_cpuload(i);
3410 if (rq->nr_running == 1 && wl > imbalance)
3413 if (wl > max_load) {
3423 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
3424 * so long as it is large enough.
3426 #define MAX_PINNED_INTERVAL 512
3429 * Check this_cpu to ensure it is balanced within domain. Attempt to move
3430 * tasks if there is an imbalance.
3432 static int load_balance(int this_cpu, struct rq *this_rq,
3433 struct sched_domain *sd, enum cpu_idle_type idle,
3434 int *balance, cpumask_t *cpus)
3436 int ld_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
3437 struct sched_group *group;
3438 unsigned long imbalance;
3440 unsigned long flags;
3445 * When power savings policy is enabled for the parent domain, idle
3446 * sibling can pick up load irrespective of busy siblings. In this case,
3447 * let the state of idle sibling percolate up as CPU_IDLE, instead of
3448 * portraying it as CPU_NOT_IDLE.
3450 if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
3451 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3454 schedstat_inc(sd, lb_count[idle]);
3458 group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
3465 schedstat_inc(sd, lb_nobusyg[idle]);
3469 busiest = find_busiest_queue(group, idle, imbalance, cpus);
3471 schedstat_inc(sd, lb_nobusyq[idle]);
3475 BUG_ON(busiest == this_rq);
3477 schedstat_add(sd, lb_imbalance[idle], imbalance);
3480 if (busiest->nr_running > 1) {
3482 * Attempt to move tasks. If find_busiest_group has found
3483 * an imbalance but busiest->nr_running <= 1, the group is
3484 * still unbalanced. ld_moved simply stays zero, so it is
3485 * correctly treated as an imbalance.
3487 local_irq_save(flags);
3488 double_rq_lock(this_rq, busiest);
3489 ld_moved = move_tasks(this_rq, this_cpu, busiest,
3490 imbalance, sd, idle, &all_pinned);
3491 double_rq_unlock(this_rq, busiest);
3492 local_irq_restore(flags);
3495 * some other cpu did the load balance for us.
3497 if (ld_moved && this_cpu != smp_processor_id())
3498 resched_cpu(this_cpu);
3500 /* All tasks on this runqueue were pinned by CPU affinity */
3501 if (unlikely(all_pinned)) {
3502 cpu_clear(cpu_of(busiest), *cpus);
3503 if (!cpus_empty(*cpus))
3510 schedstat_inc(sd, lb_failed[idle]);
3511 sd->nr_balance_failed++;
3513 if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
3515 spin_lock_irqsave(&busiest->lock, flags);
3517 /* don't kick the migration_thread, if the curr
3518 * task on busiest cpu can't be moved to this_cpu
3520 if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) {
3521 spin_unlock_irqrestore(&busiest->lock, flags);
3523 goto out_one_pinned;
3526 if (!busiest->active_balance) {
3527 busiest->active_balance = 1;
3528 busiest->push_cpu = this_cpu;
3531 spin_unlock_irqrestore(&busiest->lock, flags);
3533 wake_up_process(busiest->migration_thread);
3536 * We've kicked active balancing, reset the failure
3539 sd->nr_balance_failed = sd->cache_nice_tries+1;
3542 sd->nr_balance_failed = 0;
3544 if (likely(!active_balance)) {
3545 /* We were unbalanced, so reset the balancing interval */
3546 sd->balance_interval = sd->min_interval;
3549 * If we've begun active balancing, start to back off. This
3550 * case may not be covered by the all_pinned logic if there
3551 * is only 1 task on the busy runqueue (because we don't call
3554 if (sd->balance_interval < sd->max_interval)
3555 sd->balance_interval *= 2;
3558 if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
3559 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3565 schedstat_inc(sd, lb_balanced[idle]);
3567 sd->nr_balance_failed = 0;
3570 /* tune up the balancing interval */
3571 if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
3572 (sd->balance_interval < sd->max_interval))
3573 sd->balance_interval *= 2;
3575 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
3576 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3587 * Check this_cpu to ensure it is balanced within domain. Attempt to move
3588 * tasks if there is an imbalance.
3590 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
3591 * this_rq is locked.
3594 load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd,
3597 struct sched_group *group;
3598 struct rq *busiest = NULL;
3599 unsigned long imbalance;
3607 * When power savings policy is enabled for the parent domain, idle
3608 * sibling can pick up load irrespective of busy siblings. In this case,
3609 * let the state of idle sibling percolate up as IDLE, instead of
3610 * portraying it as CPU_NOT_IDLE.
3612 if (sd->flags & SD_SHARE_CPUPOWER &&
3613 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3616 schedstat_inc(sd, lb_count[CPU_NEWLY_IDLE]);
3618 update_shares_locked(this_rq, sd);
3619 group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE,
3620 &sd_idle, cpus, NULL);
3622 schedstat_inc(sd, lb_nobusyg[CPU_NEWLY_IDLE]);
3626 busiest = find_busiest_queue(group, CPU_NEWLY_IDLE, imbalance, cpus);
3628 schedstat_inc(sd, lb_nobusyq[CPU_NEWLY_IDLE]);
3632 BUG_ON(busiest == this_rq);
3634 schedstat_add(sd, lb_imbalance[CPU_NEWLY_IDLE], imbalance);
3637 if (busiest->nr_running > 1) {
3638 /* Attempt to move tasks */
3639 double_lock_balance(this_rq, busiest);
3640 /* this_rq->clock is already updated */
3641 update_rq_clock(busiest);
3642 ld_moved = move_tasks(this_rq, this_cpu, busiest,
3643 imbalance, sd, CPU_NEWLY_IDLE,
3645 spin_unlock(&busiest->lock);
3647 if (unlikely(all_pinned)) {
3648 cpu_clear(cpu_of(busiest), *cpus);
3649 if (!cpus_empty(*cpus))
3655 schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
3656 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
3657 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3660 sd->nr_balance_failed = 0;
3662 update_shares_locked(this_rq, sd);
3666 schedstat_inc(sd, lb_balanced[CPU_NEWLY_IDLE]);
3667 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
3668 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3670 sd->nr_balance_failed = 0;
3676 * idle_balance is called by schedule() if this_cpu is about to become
3677 * idle. Attempts to pull tasks from other CPUs.
3679 static void idle_balance(int this_cpu, struct rq *this_rq)
3681 struct sched_domain *sd;
3682 int pulled_task = -1;
3683 unsigned long next_balance = jiffies + HZ;
3686 for_each_domain(this_cpu, sd) {
3687 unsigned long interval;
3689 if (!(sd->flags & SD_LOAD_BALANCE))
3692 if (sd->flags & SD_BALANCE_NEWIDLE)
3693 /* If we've pulled tasks over stop searching: */
3694 pulled_task = load_balance_newidle(this_cpu, this_rq,
3697 interval = msecs_to_jiffies(sd->balance_interval);
3698 if (time_after(next_balance, sd->last_balance + interval))
3699 next_balance = sd->last_balance + interval;
3703 if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
3705 * We are going idle. next_balance may be set based on
3706 * a busy processor. So reset next_balance.
3708 this_rq->next_balance = next_balance;
3713 * active_load_balance is run by migration threads. It pushes running tasks
3714 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
3715 * running on each physical CPU where possible, and avoids physical /
3716 * logical imbalances.
3718 * Called with busiest_rq locked.
3720 static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
3722 int target_cpu = busiest_rq->push_cpu;
3723 struct sched_domain *sd;
3724 struct rq *target_rq;
3726 /* Is there any task to move? */
3727 if (busiest_rq->nr_running <= 1)
3730 target_rq = cpu_rq(target_cpu);
3733 * This condition is "impossible", if it occurs
3734 * we need to fix it. Originally reported by
3735 * Bjorn Helgaas on a 128-cpu setup.
3737 BUG_ON(busiest_rq == target_rq);
3739 /* move a task from busiest_rq to target_rq */
3740 double_lock_balance(busiest_rq, target_rq);
3741 update_rq_clock(busiest_rq);
3742 update_rq_clock(target_rq);
3744 /* Search for an sd spanning us and the target CPU. */
3745 for_each_domain(target_cpu, sd) {
3746 if ((sd->flags & SD_LOAD_BALANCE) &&
3747 cpu_isset(busiest_cpu, sd->span))
3752 schedstat_inc(sd, alb_count);
3754 if (move_one_task(target_rq, target_cpu, busiest_rq,
3756 schedstat_inc(sd, alb_pushed);
3758 schedstat_inc(sd, alb_failed);
3760 spin_unlock(&target_rq->lock);
3765 atomic_t load_balancer;
3767 } nohz ____cacheline_aligned = {
3768 .load_balancer = ATOMIC_INIT(-1),
3769 .cpu_mask = CPU_MASK_NONE,
3773 * This routine will try to nominate the ilb (idle load balancing)
3774 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
3775 * load balancing on behalf of all those cpus. If all the cpus in the system
3776 * go into this tickless mode, then there will be no ilb owner (as there is
3777 * no need for one) and all the cpus will sleep till the next wakeup event
3780 * For the ilb owner, tick is not stopped. And this tick will be used
3781 * for idle load balancing. ilb owner will still be part of
3784 * While stopping the tick, this cpu will become the ilb owner if there
3785 * is no other owner. And will be the owner till that cpu becomes busy
3786 * or if all cpus in the system stop their ticks at which point
3787 * there is no need for ilb owner.
3789 * When the ilb owner becomes busy, it nominates another owner, during the
3790 * next busy scheduler_tick()
3792 int select_nohz_load_balancer(int stop_tick)
3794 int cpu = smp_processor_id();
3797 cpu_set(cpu, nohz.cpu_mask);
3798 cpu_rq(cpu)->in_nohz_recently = 1;
3801 * If we are going offline and still the leader, give up!
3803 if (cpu_is_offline(cpu) &&
3804 atomic_read(&nohz.load_balancer) == cpu) {
3805 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
3810 /* time for ilb owner also to sleep */
3811 if (cpus_weight(nohz.cpu_mask) == num_online_cpus()) {
3812 if (atomic_read(&nohz.load_balancer) == cpu)
3813 atomic_set(&nohz.load_balancer, -1);
3817 if (atomic_read(&nohz.load_balancer) == -1) {
3818 /* make me the ilb owner */
3819 if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
3821 } else if (atomic_read(&nohz.load_balancer) == cpu)
3824 if (!cpu_isset(cpu, nohz.cpu_mask))
3827 cpu_clear(cpu, nohz.cpu_mask);
3829 if (atomic_read(&nohz.load_balancer) == cpu)
3830 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
3837 static DEFINE_SPINLOCK(balancing);
3840 * It checks each scheduling domain to see if it is due to be balanced,
3841 * and initiates a balancing operation if so.
3843 * Balancing parameters are set up in arch_init_sched_domains.
3845 static void rebalance_domains(int cpu, enum cpu_idle_type idle)
3848 struct rq *rq = cpu_rq(cpu);
3849 unsigned long interval;
3850 struct sched_domain *sd;
3851 /* Earliest time when we have to do rebalance again */
3852 unsigned long next_balance = jiffies + 60*HZ;
3853 int update_next_balance = 0;
3857 for_each_domain(cpu, sd) {
3858 if (!(sd->flags & SD_LOAD_BALANCE))
3861 interval = sd->balance_interval;
3862 if (idle != CPU_IDLE)
3863 interval *= sd->busy_factor;
3865 /* scale ms to jiffies */
3866 interval = msecs_to_jiffies(interval);
3867 if (unlikely(!interval))
3869 if (interval > HZ*NR_CPUS/10)
3870 interval = HZ*NR_CPUS/10;
3872 need_serialize = sd->flags & SD_SERIALIZE;
3874 if (need_serialize) {
3875 if (!spin_trylock(&balancing))
3879 if (time_after_eq(jiffies, sd->last_balance + interval)) {
3880 if (load_balance(cpu, rq, sd, idle, &balance, &tmp)) {
3882 * We've pulled tasks over so either we're no
3883 * longer idle, or one of our SMT siblings is
3886 idle = CPU_NOT_IDLE;
3888 sd->last_balance = jiffies;
3891 spin_unlock(&balancing);
3893 if (time_after(next_balance, sd->last_balance + interval)) {
3894 next_balance = sd->last_balance + interval;
3895 update_next_balance = 1;
3899 * Stop the load balance at this level. There is another
3900 * CPU in our sched group which is doing load balancing more
3908 * next_balance will be updated only when there is a need.
3909 * When the cpu is attached to null domain for ex, it will not be
3912 if (likely(update_next_balance))
3913 rq->next_balance = next_balance;
3917 * run_rebalance_domains is triggered when needed from the scheduler tick.
3918 * In CONFIG_NO_HZ case, the idle load balance owner will do the
3919 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3921 static void run_rebalance_domains(struct softirq_action *h)
3923 int this_cpu = smp_processor_id();
3924 struct rq *this_rq = cpu_rq(this_cpu);
3925 enum cpu_idle_type idle = this_rq->idle_at_tick ?
3926 CPU_IDLE : CPU_NOT_IDLE;
3928 rebalance_domains(this_cpu, idle);
3932 * If this cpu is the owner for idle load balancing, then do the
3933 * balancing on behalf of the other idle cpus whose ticks are
3936 if (this_rq->idle_at_tick &&
3937 atomic_read(&nohz.load_balancer) == this_cpu) {
3938 cpumask_t cpus = nohz.cpu_mask;
3942 cpu_clear(this_cpu, cpus);
3943 for_each_cpu_mask(balance_cpu, cpus) {
3945 * If this cpu gets work to do, stop the load balancing
3946 * work being done for other cpus. Next load
3947 * balancing owner will pick it up.
3952 rebalance_domains(balance_cpu, CPU_IDLE);
3954 rq = cpu_rq(balance_cpu);
3955 if (time_after(this_rq->next_balance, rq->next_balance))
3956 this_rq->next_balance = rq->next_balance;
3963 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3965 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3966 * idle load balancing owner or decide to stop the periodic load balancing,
3967 * if the whole system is idle.
3969 static inline void trigger_load_balance(struct rq *rq, int cpu)
3973 * If we were in the nohz mode recently and busy at the current
3974 * scheduler tick, then check if we need to nominate new idle
3977 if (rq->in_nohz_recently && !rq->idle_at_tick) {
3978 rq->in_nohz_recently = 0;
3980 if (atomic_read(&nohz.load_balancer) == cpu) {
3981 cpu_clear(cpu, nohz.cpu_mask);
3982 atomic_set(&nohz.load_balancer, -1);
3985 if (atomic_read(&nohz.load_balancer) == -1) {
3987 * simple selection for now: Nominate the
3988 * first cpu in the nohz list to be the next
3991 * TBD: Traverse the sched domains and nominate
3992 * the nearest cpu in the nohz.cpu_mask.
3994 int ilb = first_cpu(nohz.cpu_mask);
3996 if (ilb < nr_cpu_ids)
4002 * If this cpu is idle and doing idle load balancing for all the
4003 * cpus with ticks stopped, is it time for that to stop?
4005 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
4006 cpus_weight(nohz.cpu_mask) == num_online_cpus()) {
4012 * If this cpu is idle and the idle load balancing is done by
4013 * someone else, then no need raise the SCHED_SOFTIRQ
4015 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
4016 cpu_isset(cpu, nohz.cpu_mask))
4019 if (time_after_eq(jiffies, rq->next_balance))
4020 raise_softirq(SCHED_SOFTIRQ);
4023 #else /* CONFIG_SMP */
4026 * on UP we do not need to balance between CPUs:
4028 static inline void idle_balance(int cpu, struct rq *rq)
4034 DEFINE_PER_CPU(struct kernel_stat, kstat);
4036 EXPORT_PER_CPU_SYMBOL(kstat);
4039 * Return p->sum_exec_runtime plus any more ns on the sched_clock
4040 * that have not yet been banked in case the task is currently running.
4042 unsigned long long task_sched_runtime(struct task_struct *p)
4044 unsigned long flags;
4048 rq = task_rq_lock(p, &flags);
4049 ns = p->se.sum_exec_runtime;
4050 if (task_current(rq, p)) {
4051 update_rq_clock(rq);
4052 delta_exec = rq->clock - p->se.exec_start;
4053 if ((s64)delta_exec > 0)
4056 task_rq_unlock(rq, &flags);
4062 * Account user cpu time to a process.
4063 * @p: the process that the cpu time gets accounted to
4064 * @cputime: the cpu time spent in user space since the last update
4066 void account_user_time(struct task_struct *p, cputime_t cputime)
4068 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
4071 p->utime = cputime_add(p->utime, cputime);
4073 /* Add user time to cpustat. */
4074 tmp = cputime_to_cputime64(cputime);
4075 if (TASK_NICE(p) > 0)
4076 cpustat->nice = cputime64_add(cpustat->nice, tmp);
4078 cpustat->user = cputime64_add(cpustat->user, tmp);
4082 * Account guest cpu time to a process.
4083 * @p: the process that the cpu time gets accounted to
4084 * @cputime: the cpu time spent in virtual machine since the last update
4086 static void account_guest_time(struct task_struct *p, cputime_t cputime)
4089 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
4091 tmp = cputime_to_cputime64(cputime);
4093 p->utime = cputime_add(p->utime, cputime);
4094 p->gtime = cputime_add(p->gtime, cputime);
4096 cpustat->user = cputime64_add(cpustat->user, tmp);
4097 cpustat->guest = cputime64_add(cpustat->guest, tmp);
4101 * Account scaled user cpu time to a process.
4102 * @p: the process that the cpu time gets accounted to
4103 * @cputime: the cpu time spent in user space since the last update
4105 void account_user_time_scaled(struct task_struct *p, cputime_t cputime)
4107 p->utimescaled = cputime_add(p->utimescaled, cputime);
4111 * Account system cpu time to a process.
4112 * @p: the process that the cpu time gets accounted to
4113 * @hardirq_offset: the offset to subtract from hardirq_count()
4114 * @cputime: the cpu time spent in kernel space since the last update
4116 void account_system_time(struct task_struct *p, int hardirq_offset,
4119 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
4120 struct rq *rq = this_rq();
4123 if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
4124 account_guest_time(p, cputime);
4128 p->stime = cputime_add(p->stime, cputime);
4130 /* Add system time to cpustat. */
4131 tmp = cputime_to_cputime64(cputime);
4132 if (hardirq_count() - hardirq_offset)
4133 cpustat->irq = cputime64_add(cpustat->irq, tmp);
4134 else if (softirq_count())
4135 cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
4136 else if (p != rq->idle)
4137 cpustat->system = cputime64_add(cpustat->system, tmp);
4138 else if (atomic_read(&rq->nr_iowait) > 0)
4139 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
4141 cpustat->idle = cputime64_add(cpustat->idle, tmp);
4142 /* Account for system time used */
4143 acct_update_integrals(p);
4147 * Account scaled system cpu time to a process.
4148 * @p: the process that the cpu time gets accounted to
4149 * @hardirq_offset: the offset to subtract from hardirq_count()
4150 * @cputime: the cpu time spent in kernel space since the last update
4152 void account_system_time_scaled(struct task_struct *p, cputime_t cputime)
4154 p->stimescaled = cputime_add(p->stimescaled, cputime);
4158 * Account for involuntary wait time.
4159 * @p: the process from which the cpu time has been stolen
4160 * @steal: the cpu time spent in involuntary wait
4162 void account_steal_time(struct task_struct *p, cputime_t steal)
4164 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
4165 cputime64_t tmp = cputime_to_cputime64(steal);
4166 struct rq *rq = this_rq();
4168 if (p == rq->idle) {
4169 p->stime = cputime_add(p->stime, steal);
4170 if (atomic_read(&rq->nr_iowait) > 0)
4171 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
4173 cpustat->idle = cputime64_add(cpustat->idle, tmp);
4175 cpustat->steal = cputime64_add(cpustat->steal, tmp);
4179 * This function gets called by the timer code, with HZ frequency.
4180 * We call it with interrupts disabled.
4182 * It also gets called by the fork code, when changing the parent's
4185 void scheduler_tick(void)
4187 int cpu = smp_processor_id();
4188 struct rq *rq = cpu_rq(cpu);
4189 struct task_struct *curr = rq->curr;
4193 spin_lock(&rq->lock);
4194 update_rq_clock(rq);
4195 update_cpu_load(rq);
4196 curr->sched_class->task_tick(rq, curr, 0);
4197 spin_unlock(&rq->lock);
4200 rq->idle_at_tick = idle_cpu(cpu);
4201 trigger_load_balance(rq, cpu);
4205 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
4207 void __kprobes add_preempt_count(int val)
4212 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
4214 preempt_count() += val;
4216 * Spinlock count overflowing soon?
4218 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
4221 EXPORT_SYMBOL(add_preempt_count);
4223 void __kprobes sub_preempt_count(int val)
4228 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
4231 * Is the spinlock portion underflowing?
4233 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
4234 !(preempt_count() & PREEMPT_MASK)))
4237 preempt_count() -= val;
4239 EXPORT_SYMBOL(sub_preempt_count);
4244 * Print scheduling while atomic bug:
4246 static noinline void __schedule_bug(struct task_struct *prev)
4248 struct pt_regs *regs = get_irq_regs();
4250 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
4251 prev->comm, prev->pid, preempt_count());
4253 debug_show_held_locks(prev);
4255 if (irqs_disabled())
4256 print_irqtrace_events(prev);
4265 * Various schedule()-time debugging checks and statistics:
4267 static inline void schedule_debug(struct task_struct *prev)
4270 * Test if we are atomic. Since do_exit() needs to call into
4271 * schedule() atomically, we ignore that path for now.
4272 * Otherwise, whine if we are scheduling when we should not be.
4274 if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
4275 __schedule_bug(prev);
4277 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
4279 schedstat_inc(this_rq(), sched_count);
4280 #ifdef CONFIG_SCHEDSTATS
4281 if (unlikely(prev->lock_depth >= 0)) {
4282 schedstat_inc(this_rq(), bkl_count);
4283 schedstat_inc(prev, sched_info.bkl_count);
4289 * Pick up the highest-prio task:
4291 static inline struct task_struct *
4292 pick_next_task(struct rq *rq, struct task_struct *prev)
4294 const struct sched_class *class;
4295 struct task_struct *p;
4298 * Optimization: we know that if all tasks are in
4299 * the fair class we can call that function directly:
4301 if (likely(rq->nr_running == rq->cfs.nr_running)) {
4302 p = fair_sched_class.pick_next_task(rq);
4307 class = sched_class_highest;
4309 p = class->pick_next_task(rq);
4313 * Will never be NULL as the idle class always
4314 * returns a non-NULL p:
4316 class = class->next;
4321 * schedule() is the main scheduler function.
4323 asmlinkage void __sched schedule(void)
4325 struct task_struct *prev, *next;
4326 unsigned long *switch_count;
4328 int cpu, hrtick = sched_feat(HRTICK);
4332 cpu = smp_processor_id();
4336 switch_count = &prev->nivcsw;
4338 release_kernel_lock(prev);
4339 need_resched_nonpreemptible:
4341 schedule_debug(prev);
4347 * Do the rq-clock update outside the rq lock:
4349 local_irq_disable();
4350 update_rq_clock(rq);
4351 spin_lock(&rq->lock);
4352 clear_tsk_need_resched(prev);
4354 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
4355 if (unlikely(signal_pending_state(prev->state, prev)))
4356 prev->state = TASK_RUNNING;
4358 deactivate_task(rq, prev, 1);
4359 switch_count = &prev->nvcsw;
4363 if (prev->sched_class->pre_schedule)
4364 prev->sched_class->pre_schedule(rq, prev);
4367 if (unlikely(!rq->nr_running))
4368 idle_balance(cpu, rq);
4370 prev->sched_class->put_prev_task(rq, prev);
4371 next = pick_next_task(rq, prev);
4373 if (likely(prev != next)) {
4374 sched_info_switch(prev, next);
4380 context_switch(rq, prev, next); /* unlocks the rq */
4382 * the context switch might have flipped the stack from under
4383 * us, hence refresh the local variables.
4385 cpu = smp_processor_id();
4388 spin_unlock_irq(&rq->lock);
4393 if (unlikely(reacquire_kernel_lock(current) < 0))
4394 goto need_resched_nonpreemptible;
4396 preempt_enable_no_resched();
4397 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
4400 EXPORT_SYMBOL(schedule);
4402 #ifdef CONFIG_PREEMPT
4404 * this is the entry point to schedule() from in-kernel preemption
4405 * off of preempt_enable. Kernel preemptions off return from interrupt
4406 * occur there and call schedule directly.
4408 asmlinkage void __sched preempt_schedule(void)
4410 struct thread_info *ti = current_thread_info();
4413 * If there is a non-zero preempt_count or interrupts are disabled,
4414 * we do not want to preempt the current task. Just return..
4416 if (likely(ti->preempt_count || irqs_disabled()))
4420 add_preempt_count(PREEMPT_ACTIVE);
4422 sub_preempt_count(PREEMPT_ACTIVE);
4425 * Check again in case we missed a preemption opportunity
4426 * between schedule and now.
4429 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED)));
4431 EXPORT_SYMBOL(preempt_schedule);
4434 * this is the entry point to schedule() from kernel preemption
4435 * off of irq context.
4436 * Note, that this is called and return with irqs disabled. This will
4437 * protect us against recursive calling from irq.
4439 asmlinkage void __sched preempt_schedule_irq(void)
4441 struct thread_info *ti = current_thread_info();
4443 /* Catch callers which need to be fixed */
4444 BUG_ON(ti->preempt_count || !irqs_disabled());
4447 add_preempt_count(PREEMPT_ACTIVE);
4450 local_irq_disable();
4451 sub_preempt_count(PREEMPT_ACTIVE);
4454 * Check again in case we missed a preemption opportunity
4455 * between schedule and now.
4458 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED)));
4461 #endif /* CONFIG_PREEMPT */
4463 int default_wake_function(wait_queue_t *curr, unsigned mode, int sync,
4466 return try_to_wake_up(curr->private, mode, sync);
4468 EXPORT_SYMBOL(default_wake_function);
4471 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
4472 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
4473 * number) then we wake all the non-exclusive tasks and one exclusive task.
4475 * There are circumstances in which we can try to wake a task which has already
4476 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
4477 * zero in this (rare) case, and we handle it by continuing to scan the queue.
4479 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
4480 int nr_exclusive, int sync, void *key)
4482 wait_queue_t *curr, *next;
4484 list_for_each_entry_safe(curr, next, &q->task_list, task_list) {
4485 unsigned flags = curr->flags;
4487 if (curr->func(curr, mode, sync, key) &&
4488 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
4494 * __wake_up - wake up threads blocked on a waitqueue.
4496 * @mode: which threads
4497 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4498 * @key: is directly passed to the wakeup function
4500 void __wake_up(wait_queue_head_t *q, unsigned int mode,
4501 int nr_exclusive, void *key)
4503 unsigned long flags;
4505 spin_lock_irqsave(&q->lock, flags);
4506 __wake_up_common(q, mode, nr_exclusive, 0, key);
4507 spin_unlock_irqrestore(&q->lock, flags);
4509 EXPORT_SYMBOL(__wake_up);
4512 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
4514 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
4516 __wake_up_common(q, mode, 1, 0, NULL);
4520 * __wake_up_sync - wake up threads blocked on a waitqueue.
4522 * @mode: which threads
4523 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4525 * The sync wakeup differs that the waker knows that it will schedule
4526 * away soon, so while the target thread will be woken up, it will not
4527 * be migrated to another CPU - ie. the two threads are 'synchronized'
4528 * with each other. This can prevent needless bouncing between CPUs.
4530 * On UP it can prevent extra preemption.
4533 __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
4535 unsigned long flags;
4541 if (unlikely(!nr_exclusive))
4544 spin_lock_irqsave(&q->lock, flags);
4545 __wake_up_common(q, mode, nr_exclusive, sync, NULL);
4546 spin_unlock_irqrestore(&q->lock, flags);
4548 EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
4550 void complete(struct completion *x)
4552 unsigned long flags;
4554 spin_lock_irqsave(&x->wait.lock, flags);
4556 __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL);
4557 spin_unlock_irqrestore(&x->wait.lock, flags);
4559 EXPORT_SYMBOL(complete);
4561 void complete_all(struct completion *x)
4563 unsigned long flags;
4565 spin_lock_irqsave(&x->wait.lock, flags);
4566 x->done += UINT_MAX/2;
4567 __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL);
4568 spin_unlock_irqrestore(&x->wait.lock, flags);
4570 EXPORT_SYMBOL(complete_all);
4572 static inline long __sched
4573 do_wait_for_common(struct completion *x, long timeout, int state)
4576 DECLARE_WAITQUEUE(wait, current);
4578 wait.flags |= WQ_FLAG_EXCLUSIVE;
4579 __add_wait_queue_tail(&x->wait, &wait);
4581 if ((state == TASK_INTERRUPTIBLE &&
4582 signal_pending(current)) ||
4583 (state == TASK_KILLABLE &&
4584 fatal_signal_pending(current))) {
4585 timeout = -ERESTARTSYS;
4588 __set_current_state(state);
4589 spin_unlock_irq(&x->wait.lock);
4590 timeout = schedule_timeout(timeout);
4591 spin_lock_irq(&x->wait.lock);
4592 } while (!x->done && timeout);
4593 __remove_wait_queue(&x->wait, &wait);
4598 return timeout ?: 1;
4602 wait_for_common(struct completion *x, long timeout, int state)
4606 spin_lock_irq(&x->wait.lock);
4607 timeout = do_wait_for_common(x, timeout, state);
4608 spin_unlock_irq(&x->wait.lock);
4612 void __sched wait_for_completion(struct completion *x)
4614 wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
4616 EXPORT_SYMBOL(wait_for_completion);
4618 unsigned long __sched
4619 wait_for_completion_timeout(struct completion *x, unsigned long timeout)
4621 return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE);
4623 EXPORT_SYMBOL(wait_for_completion_timeout);
4625 int __sched wait_for_completion_interruptible(struct completion *x)
4627 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
4628 if (t == -ERESTARTSYS)
4632 EXPORT_SYMBOL(wait_for_completion_interruptible);
4634 unsigned long __sched
4635 wait_for_completion_interruptible_timeout(struct completion *x,
4636 unsigned long timeout)
4638 return wait_for_common(x, timeout, TASK_INTERRUPTIBLE);
4640 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
4642 int __sched wait_for_completion_killable(struct completion *x)
4644 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE);
4645 if (t == -ERESTARTSYS)
4649 EXPORT_SYMBOL(wait_for_completion_killable);
4652 sleep_on_common(wait_queue_head_t *q, int state, long timeout)
4654 unsigned long flags;
4657 init_waitqueue_entry(&wait, current);
4659 __set_current_state(state);
4661 spin_lock_irqsave(&q->lock, flags);
4662 __add_wait_queue(q, &wait);
4663 spin_unlock(&q->lock);
4664 timeout = schedule_timeout(timeout);
4665 spin_lock_irq(&q->lock);
4666 __remove_wait_queue(q, &wait);
4667 spin_unlock_irqrestore(&q->lock, flags);
4672 void __sched interruptible_sleep_on(wait_queue_head_t *q)
4674 sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
4676 EXPORT_SYMBOL(interruptible_sleep_on);
4679 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
4681 return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
4683 EXPORT_SYMBOL(interruptible_sleep_on_timeout);
4685 void __sched sleep_on(wait_queue_head_t *q)
4687 sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
4689 EXPORT_SYMBOL(sleep_on);
4691 long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
4693 return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
4695 EXPORT_SYMBOL(sleep_on_timeout);
4697 #ifdef CONFIG_RT_MUTEXES
4700 * rt_mutex_setprio - set the current priority of a task
4702 * @prio: prio value (kernel-internal form)
4704 * This function changes the 'effective' priority of a task. It does
4705 * not touch ->normal_prio like __setscheduler().
4707 * Used by the rt_mutex code to implement priority inheritance logic.
4709 void rt_mutex_setprio(struct task_struct *p, int prio)
4711 unsigned long flags;
4712 int oldprio, on_rq, running;
4714 const struct sched_class *prev_class = p->sched_class;
4716 BUG_ON(prio < 0 || prio > MAX_PRIO);
4718 rq = task_rq_lock(p, &flags);
4719 update_rq_clock(rq);
4722 on_rq = p->se.on_rq;
4723 running = task_current(rq, p);
4725 dequeue_task(rq, p, 0);
4727 p->sched_class->put_prev_task(rq, p);
4730 p->sched_class = &rt_sched_class;
4732 p->sched_class = &fair_sched_class;
4737 p->sched_class->set_curr_task(rq);
4739 enqueue_task(rq, p, 0);
4741 check_class_changed(rq, p, prev_class, oldprio, running);
4743 task_rq_unlock(rq, &flags);
4748 void set_user_nice(struct task_struct *p, long nice)
4750 int old_prio, delta, on_rq;
4751 unsigned long flags;
4754 if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
4757 * We have to be careful, if called from sys_setpriority(),
4758 * the task might be in the middle of scheduling on another CPU.
4760 rq = task_rq_lock(p, &flags);
4761 update_rq_clock(rq);
4763 * The RT priorities are set via sched_setscheduler(), but we still
4764 * allow the 'normal' nice value to be set - but as expected
4765 * it wont have any effect on scheduling until the task is
4766 * SCHED_FIFO/SCHED_RR:
4768 if (task_has_rt_policy(p)) {
4769 p->static_prio = NICE_TO_PRIO(nice);
4772 on_rq = p->se.on_rq;
4774 dequeue_task(rq, p, 0);
4776 p->static_prio = NICE_TO_PRIO(nice);
4779 p->prio = effective_prio(p);
4780 delta = p->prio - old_prio;
4783 enqueue_task(rq, p, 0);
4785 * If the task increased its priority or is running and
4786 * lowered its priority, then reschedule its CPU:
4788 if (delta < 0 || (delta > 0 && task_running(rq, p)))
4789 resched_task(rq->curr);
4792 task_rq_unlock(rq, &flags);
4794 EXPORT_SYMBOL(set_user_nice);
4797 * can_nice - check if a task can reduce its nice value
4801 int can_nice(const struct task_struct *p, const int nice)
4803 /* convert nice value [19,-20] to rlimit style value [1,40] */
4804 int nice_rlim = 20 - nice;
4806 return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
4807 capable(CAP_SYS_NICE));
4810 #ifdef __ARCH_WANT_SYS_NICE
4813 * sys_nice - change the priority of the current process.
4814 * @increment: priority increment
4816 * sys_setpriority is a more generic, but much slower function that
4817 * does similar things.
4819 asmlinkage long sys_nice(int increment)
4824 * Setpriority might change our priority at the same moment.
4825 * We don't have to worry. Conceptually one call occurs first
4826 * and we have a single winner.
4828 if (increment < -40)
4833 nice = PRIO_TO_NICE(current->static_prio) + increment;
4839 if (increment < 0 && !can_nice(current, nice))
4842 retval = security_task_setnice(current, nice);
4846 set_user_nice(current, nice);
4853 * task_prio - return the priority value of a given task.
4854 * @p: the task in question.
4856 * This is the priority value as seen by users in /proc.
4857 * RT tasks are offset by -200. Normal tasks are centered
4858 * around 0, value goes from -16 to +15.
4860 int task_prio(const struct task_struct *p)
4862 return p->prio - MAX_RT_PRIO;
4866 * task_nice - return the nice value of a given task.
4867 * @p: the task in question.
4869 int task_nice(const struct task_struct *p)
4871 return TASK_NICE(p);
4873 EXPORT_SYMBOL(task_nice);
4876 * idle_cpu - is a given cpu idle currently?
4877 * @cpu: the processor in question.
4879 int idle_cpu(int cpu)
4881 return cpu_curr(cpu) == cpu_rq(cpu)->idle;
4885 * idle_task - return the idle task for a given cpu.
4886 * @cpu: the processor in question.
4888 struct task_struct *idle_task(int cpu)
4890 return cpu_rq(cpu)->idle;
4894 * find_process_by_pid - find a process with a matching PID value.
4895 * @pid: the pid in question.
4897 static struct task_struct *find_process_by_pid(pid_t pid)
4899 return pid ? find_task_by_vpid(pid) : current;
4902 /* Actually do priority change: must hold rq lock. */
4904 __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
4906 BUG_ON(p->se.on_rq);
4909 switch (p->policy) {
4913 p->sched_class = &fair_sched_class;
4917 p->sched_class = &rt_sched_class;
4921 p->rt_priority = prio;
4922 p->normal_prio = normal_prio(p);
4923 /* we are holding p->pi_lock already */
4924 p->prio = rt_mutex_getprio(p);
4929 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4930 * @p: the task in question.
4931 * @policy: new policy.
4932 * @param: structure containing the new RT priority.
4934 * NOTE that the task may be already dead.
4936 int sched_setscheduler(struct task_struct *p, int policy,
4937 struct sched_param *param)
4939 int retval, oldprio, oldpolicy = -1, on_rq, running;
4940 unsigned long flags;
4941 const struct sched_class *prev_class = p->sched_class;
4944 /* may grab non-irq protected spin_locks */
4945 BUG_ON(in_interrupt());
4947 /* double check policy once rq lock held */
4949 policy = oldpolicy = p->policy;
4950 else if (policy != SCHED_FIFO && policy != SCHED_RR &&
4951 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
4952 policy != SCHED_IDLE)
4955 * Valid priorities for SCHED_FIFO and SCHED_RR are
4956 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4957 * SCHED_BATCH and SCHED_IDLE is 0.
4959 if (param->sched_priority < 0 ||
4960 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
4961 (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
4963 if (rt_policy(policy) != (param->sched_priority != 0))
4967 * Allow unprivileged RT tasks to decrease priority:
4969 if (!capable(CAP_SYS_NICE)) {
4970 if (rt_policy(policy)) {
4971 unsigned long rlim_rtprio;
4973 if (!lock_task_sighand(p, &flags))
4975 rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
4976 unlock_task_sighand(p, &flags);
4978 /* can't set/change the rt policy */
4979 if (policy != p->policy && !rlim_rtprio)
4982 /* can't increase priority */
4983 if (param->sched_priority > p->rt_priority &&
4984 param->sched_priority > rlim_rtprio)
4988 * Like positive nice levels, dont allow tasks to
4989 * move out of SCHED_IDLE either:
4991 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE)
4994 /* can't change other user's priorities */
4995 if ((current->euid != p->euid) &&
4996 (current->euid != p->uid))
5000 #ifdef CONFIG_RT_GROUP_SCHED
5002 * Do not allow realtime tasks into groups that have no runtime
5005 if (rt_policy(policy) && task_group(p)->rt_bandwidth.rt_runtime == 0)
5009 retval = security_task_setscheduler(p, policy, param);
5013 * make sure no PI-waiters arrive (or leave) while we are
5014 * changing the priority of the task:
5016 spin_lock_irqsave(&p->pi_lock, flags);
5018 * To be able to change p->policy safely, the apropriate
5019 * runqueue lock must be held.
5021 rq = __task_rq_lock(p);
5022 /* recheck policy now with rq lock held */
5023 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
5024 policy = oldpolicy = -1;
5025 __task_rq_unlock(rq);
5026 spin_unlock_irqrestore(&p->pi_lock, flags);
5029 update_rq_clock(rq);
5030 on_rq = p->se.on_rq;
5031 running = task_current(rq, p);
5033 deactivate_task(rq, p, 0);
5035 p->sched_class->put_prev_task(rq, p);
5038 __setscheduler(rq, p, policy, param->sched_priority);
5041 p->sched_class->set_curr_task(rq);
5043 activate_task(rq, p, 0);
5045 check_class_changed(rq, p, prev_class, oldprio, running);
5047 __task_rq_unlock(rq);
5048 spin_unlock_irqrestore(&p->pi_lock, flags);
5050 rt_mutex_adjust_pi(p);
5054 EXPORT_SYMBOL_GPL(sched_setscheduler);
5057 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
5059 struct sched_param lparam;
5060 struct task_struct *p;
5063 if (!param || pid < 0)
5065 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
5070 p = find_process_by_pid(pid);
5072 retval = sched_setscheduler(p, policy, &lparam);
5079 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
5080 * @pid: the pid in question.
5081 * @policy: new policy.
5082 * @param: structure containing the new RT priority.
5085 sys_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
5087 /* negative values for policy are not valid */
5091 return do_sched_setscheduler(pid, policy, param);
5095 * sys_sched_setparam - set/change the RT priority of a thread
5096 * @pid: the pid in question.
5097 * @param: structure containing the new RT priority.
5099 asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
5101 return do_sched_setscheduler(pid, -1, param);
5105 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
5106 * @pid: the pid in question.
5108 asmlinkage long sys_sched_getscheduler(pid_t pid)
5110 struct task_struct *p;
5117 read_lock(&tasklist_lock);
5118 p = find_process_by_pid(pid);
5120 retval = security_task_getscheduler(p);
5124 read_unlock(&tasklist_lock);
5129 * sys_sched_getscheduler - get the RT priority of a thread
5130 * @pid: the pid in question.
5131 * @param: structure containing the RT priority.
5133 asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
5135 struct sched_param lp;
5136 struct task_struct *p;
5139 if (!param || pid < 0)
5142 read_lock(&tasklist_lock);
5143 p = find_process_by_pid(pid);
5148 retval = security_task_getscheduler(p);
5152 lp.sched_priority = p->rt_priority;
5153 read_unlock(&tasklist_lock);
5156 * This one might sleep, we cannot do it with a spinlock held ...
5158 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
5163 read_unlock(&tasklist_lock);
5167 long sched_setaffinity(pid_t pid, const cpumask_t *in_mask)
5169 cpumask_t cpus_allowed;
5170 cpumask_t new_mask = *in_mask;
5171 struct task_struct *p;
5175 read_lock(&tasklist_lock);
5177 p = find_process_by_pid(pid);
5179 read_unlock(&tasklist_lock);
5185 * It is not safe to call set_cpus_allowed with the
5186 * tasklist_lock held. We will bump the task_struct's
5187 * usage count and then drop tasklist_lock.
5190 read_unlock(&tasklist_lock);
5193 if ((current->euid != p->euid) && (current->euid != p->uid) &&
5194 !capable(CAP_SYS_NICE))
5197 retval = security_task_setscheduler(p, 0, NULL);
5201 cpuset_cpus_allowed(p, &cpus_allowed);
5202 cpus_and(new_mask, new_mask, cpus_allowed);
5204 retval = set_cpus_allowed_ptr(p, &new_mask);
5207 cpuset_cpus_allowed(p, &cpus_allowed);
5208 if (!cpus_subset(new_mask, cpus_allowed)) {
5210 * We must have raced with a concurrent cpuset
5211 * update. Just reset the cpus_allowed to the
5212 * cpuset's cpus_allowed
5214 new_mask = cpus_allowed;
5224 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
5225 cpumask_t *new_mask)
5227 if (len < sizeof(cpumask_t)) {
5228 memset(new_mask, 0, sizeof(cpumask_t));
5229 } else if (len > sizeof(cpumask_t)) {
5230 len = sizeof(cpumask_t);
5232 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
5236 * sys_sched_setaffinity - set the cpu affinity of a process
5237 * @pid: pid of the process
5238 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
5239 * @user_mask_ptr: user-space pointer to the new cpu mask
5241 asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
5242 unsigned long __user *user_mask_ptr)
5247 retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
5251 return sched_setaffinity(pid, &new_mask);
5254 long sched_getaffinity(pid_t pid, cpumask_t *mask)
5256 struct task_struct *p;
5260 read_lock(&tasklist_lock);
5263 p = find_process_by_pid(pid);
5267 retval = security_task_getscheduler(p);
5271 cpus_and(*mask, p->cpus_allowed, cpu_online_map);
5274 read_unlock(&tasklist_lock);
5281 * sys_sched_getaffinity - get the cpu affinity of a process
5282 * @pid: pid of the process
5283 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
5284 * @user_mask_ptr: user-space pointer to hold the current cpu mask
5286 asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
5287 unsigned long __user *user_mask_ptr)
5292 if (len < sizeof(cpumask_t))
5295 ret = sched_getaffinity(pid, &mask);
5299 if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
5302 return sizeof(cpumask_t);
5306 * sys_sched_yield - yield the current processor to other threads.
5308 * This function yields the current CPU to other tasks. If there are no
5309 * other threads running on this CPU then this function will return.
5311 asmlinkage long sys_sched_yield(void)
5313 struct rq *rq = this_rq_lock();
5315 schedstat_inc(rq, yld_count);
5316 current->sched_class->yield_task(rq);
5319 * Since we are going to call schedule() anyway, there's
5320 * no need to preempt or enable interrupts:
5322 __release(rq->lock);
5323 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
5324 _raw_spin_unlock(&rq->lock);
5325 preempt_enable_no_resched();
5332 static void __cond_resched(void)
5334 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
5335 __might_sleep(__FILE__, __LINE__);
5338 * The BKS might be reacquired before we have dropped
5339 * PREEMPT_ACTIVE, which could trigger a second
5340 * cond_resched() call.
5343 add_preempt_count(PREEMPT_ACTIVE);
5345 sub_preempt_count(PREEMPT_ACTIVE);
5346 } while (need_resched());
5349 int __sched _cond_resched(void)
5351 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&
5352 system_state == SYSTEM_RUNNING) {
5358 EXPORT_SYMBOL(_cond_resched);
5361 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
5362 * call schedule, and on return reacquire the lock.
5364 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
5365 * operations here to prevent schedule() from being called twice (once via
5366 * spin_unlock(), once by hand).
5368 int cond_resched_lock(spinlock_t *lock)
5370 int resched = need_resched() && system_state == SYSTEM_RUNNING;
5373 if (spin_needbreak(lock) || resched) {
5375 if (resched && need_resched())
5384 EXPORT_SYMBOL(cond_resched_lock);
5386 int __sched cond_resched_softirq(void)
5388 BUG_ON(!in_softirq());
5390 if (need_resched() && system_state == SYSTEM_RUNNING) {
5398 EXPORT_SYMBOL(cond_resched_softirq);
5401 * yield - yield the current processor to other threads.
5403 * This is a shortcut for kernel-space yielding - it marks the
5404 * thread runnable and calls sys_sched_yield().
5406 void __sched yield(void)
5408 set_current_state(TASK_RUNNING);
5411 EXPORT_SYMBOL(yield);
5414 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
5415 * that process accounting knows that this is a task in IO wait state.
5417 * But don't do that if it is a deliberate, throttling IO wait (this task
5418 * has set its backing_dev_info: the queue against which it should throttle)
5420 void __sched io_schedule(void)
5422 struct rq *rq = &__raw_get_cpu_var(runqueues);
5424 delayacct_blkio_start();
5425 atomic_inc(&rq->nr_iowait);
5427 atomic_dec(&rq->nr_iowait);
5428 delayacct_blkio_end();
5430 EXPORT_SYMBOL(io_schedule);
5432 long __sched io_schedule_timeout(long timeout)
5434 struct rq *rq = &__raw_get_cpu_var(runqueues);
5437 delayacct_blkio_start();
5438 atomic_inc(&rq->nr_iowait);
5439 ret = schedule_timeout(timeout);
5440 atomic_dec(&rq->nr_iowait);
5441 delayacct_blkio_end();
5446 * sys_sched_get_priority_max - return maximum RT priority.
5447 * @policy: scheduling class.
5449 * this syscall returns the maximum rt_priority that can be used
5450 * by a given scheduling class.
5452 asmlinkage long sys_sched_get_priority_max(int policy)
5459 ret = MAX_USER_RT_PRIO-1;
5471 * sys_sched_get_priority_min - return minimum RT priority.
5472 * @policy: scheduling class.
5474 * this syscall returns the minimum rt_priority that can be used
5475 * by a given scheduling class.
5477 asmlinkage long sys_sched_get_priority_min(int policy)
5495 * sys_sched_rr_get_interval - return the default timeslice of a process.
5496 * @pid: pid of the process.
5497 * @interval: userspace pointer to the timeslice value.
5499 * this syscall writes the default timeslice value of a given process
5500 * into the user-space timespec buffer. A value of '0' means infinity.
5503 long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
5505 struct task_struct *p;
5506 unsigned int time_slice;
5514 read_lock(&tasklist_lock);
5515 p = find_process_by_pid(pid);
5519 retval = security_task_getscheduler(p);
5524 * Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER
5525 * tasks that are on an otherwise idle runqueue:
5528 if (p->policy == SCHED_RR) {
5529 time_slice = DEF_TIMESLICE;
5530 } else if (p->policy != SCHED_FIFO) {
5531 struct sched_entity *se = &p->se;
5532 unsigned long flags;
5535 rq = task_rq_lock(p, &flags);
5536 if (rq->cfs.load.weight)
5537 time_slice = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
5538 task_rq_unlock(rq, &flags);
5540 read_unlock(&tasklist_lock);
5541 jiffies_to_timespec(time_slice, &t);
5542 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
5546 read_unlock(&tasklist_lock);
5550 static const char stat_nam[] = "RSDTtZX";
5552 void sched_show_task(struct task_struct *p)
5554 unsigned long free = 0;
5557 state = p->state ? __ffs(p->state) + 1 : 0;
5558 printk(KERN_INFO "%-13.13s %c", p->comm,
5559 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
5560 #if BITS_PER_LONG == 32
5561 if (state == TASK_RUNNING)
5562 printk(KERN_CONT " running ");
5564 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
5566 if (state == TASK_RUNNING)
5567 printk(KERN_CONT " running task ");
5569 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
5571 #ifdef CONFIG_DEBUG_STACK_USAGE
5573 unsigned long *n = end_of_stack(p);
5576 free = (unsigned long)n - (unsigned long)end_of_stack(p);
5579 printk(KERN_CONT "%5lu %5d %6d\n", free,
5580 task_pid_nr(p), task_pid_nr(p->real_parent));
5582 show_stack(p, NULL);
5585 void show_state_filter(unsigned long state_filter)
5587 struct task_struct *g, *p;
5589 #if BITS_PER_LONG == 32
5591 " task PC stack pid father\n");
5594 " task PC stack pid father\n");
5596 read_lock(&tasklist_lock);
5597 do_each_thread(g, p) {
5599 * reset the NMI-timeout, listing all files on a slow
5600 * console might take alot of time:
5602 touch_nmi_watchdog();
5603 if (!state_filter || (p->state & state_filter))
5605 } while_each_thread(g, p);
5607 touch_all_softlockup_watchdogs();
5609 #ifdef CONFIG_SCHED_DEBUG
5610 sysrq_sched_debug_show();
5612 read_unlock(&tasklist_lock);
5614 * Only show locks if all tasks are dumped:
5616 if (state_filter == -1)
5617 debug_show_all_locks();
5620 void __cpuinit init_idle_bootup_task(struct task_struct *idle)
5622 idle->sched_class = &idle_sched_class;
5626 * init_idle - set up an idle thread for a given CPU
5627 * @idle: task in question
5628 * @cpu: cpu the idle task belongs to
5630 * NOTE: this function does not set the idle thread's NEED_RESCHED
5631 * flag, to make booting more robust.
5633 void __cpuinit init_idle(struct task_struct *idle, int cpu)
5635 struct rq *rq = cpu_rq(cpu);
5636 unsigned long flags;
5639 idle->se.exec_start = sched_clock();
5641 idle->prio = idle->normal_prio = MAX_PRIO;
5642 idle->cpus_allowed = cpumask_of_cpu(cpu);
5643 __set_task_cpu(idle, cpu);
5645 spin_lock_irqsave(&rq->lock, flags);
5646 rq->curr = rq->idle = idle;
5647 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
5650 spin_unlock_irqrestore(&rq->lock, flags);
5652 /* Set the preempt count _outside_ the spinlocks! */
5653 #if defined(CONFIG_PREEMPT)
5654 task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
5656 task_thread_info(idle)->preempt_count = 0;
5659 * The idle tasks have their own, simple scheduling class:
5661 idle->sched_class = &idle_sched_class;
5665 * In a system that switches off the HZ timer nohz_cpu_mask
5666 * indicates which cpus entered this state. This is used
5667 * in the rcu update to wait only for active cpus. For system
5668 * which do not switch off the HZ timer nohz_cpu_mask should
5669 * always be CPU_MASK_NONE.
5671 cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
5674 * Increase the granularity value when there are more CPUs,
5675 * because with more CPUs the 'effective latency' as visible
5676 * to users decreases. But the relationship is not linear,
5677 * so pick a second-best guess by going with the log2 of the
5680 * This idea comes from the SD scheduler of Con Kolivas:
5682 static inline void sched_init_granularity(void)
5684 unsigned int factor = 1 + ilog2(num_online_cpus());
5685 const unsigned long limit = 200000000;
5687 sysctl_sched_min_granularity *= factor;
5688 if (sysctl_sched_min_granularity > limit)
5689 sysctl_sched_min_granularity = limit;
5691 sysctl_sched_latency *= factor;
5692 if (sysctl_sched_latency > limit)
5693 sysctl_sched_latency = limit;
5695 sysctl_sched_wakeup_granularity *= factor;
5700 * This is how migration works:
5702 * 1) we queue a struct migration_req structure in the source CPU's
5703 * runqueue and wake up that CPU's migration thread.
5704 * 2) we down() the locked semaphore => thread blocks.
5705 * 3) migration thread wakes up (implicitly it forces the migrated
5706 * thread off the CPU)
5707 * 4) it gets the migration request and checks whether the migrated
5708 * task is still in the wrong runqueue.
5709 * 5) if it's in the wrong runqueue then the migration thread removes
5710 * it and puts it into the right queue.
5711 * 6) migration thread up()s the semaphore.
5712 * 7) we wake up and the migration is done.
5716 * Change a given task's CPU affinity. Migrate the thread to a
5717 * proper CPU and schedule it away if the CPU it's executing on
5718 * is removed from the allowed bitmask.
5720 * NOTE: the caller must have a valid reference to the task, the
5721 * task must not exit() & deallocate itself prematurely. The
5722 * call is not atomic; no spinlocks may be held.
5724 int set_cpus_allowed_ptr(struct task_struct *p, const cpumask_t *new_mask)
5726 struct migration_req req;
5727 unsigned long flags;
5731 rq = task_rq_lock(p, &flags);
5732 if (!cpus_intersects(*new_mask, cpu_online_map)) {
5737 if (unlikely((p->flags & PF_THREAD_BOUND) && p != current &&
5738 !cpus_equal(p->cpus_allowed, *new_mask))) {
5743 if (p->sched_class->set_cpus_allowed)
5744 p->sched_class->set_cpus_allowed(p, new_mask);
5746 p->cpus_allowed = *new_mask;
5747 p->rt.nr_cpus_allowed = cpus_weight(*new_mask);
5750 /* Can the task run on the task's current CPU? If so, we're done */
5751 if (cpu_isset(task_cpu(p), *new_mask))
5754 if (migrate_task(p, any_online_cpu(*new_mask), &req)) {
5755 /* Need help from migration thread: drop lock and wait. */
5756 task_rq_unlock(rq, &flags);
5757 wake_up_process(rq->migration_thread);
5758 wait_for_completion(&req.done);
5759 tlb_migrate_finish(p->mm);
5763 task_rq_unlock(rq, &flags);
5767 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
5770 * Move (not current) task off this cpu, onto dest cpu. We're doing
5771 * this because either it can't run here any more (set_cpus_allowed()
5772 * away from this CPU, or CPU going down), or because we're
5773 * attempting to rebalance this task on exec (sched_exec).
5775 * So we race with normal scheduler movements, but that's OK, as long
5776 * as the task is no longer on this CPU.
5778 * Returns non-zero if task was successfully migrated.
5780 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
5782 struct rq *rq_dest, *rq_src;
5785 if (unlikely(cpu_is_offline(dest_cpu)))
5788 rq_src = cpu_rq(src_cpu);
5789 rq_dest = cpu_rq(dest_cpu);
5791 double_rq_lock(rq_src, rq_dest);
5792 /* Already moved. */
5793 if (task_cpu(p) != src_cpu)
5795 /* Affinity changed (again). */
5796 if (!cpu_isset(dest_cpu, p->cpus_allowed))
5799 on_rq = p->se.on_rq;
5801 deactivate_task(rq_src, p, 0);
5803 set_task_cpu(p, dest_cpu);
5805 activate_task(rq_dest, p, 0);
5806 check_preempt_curr(rq_dest, p);
5810 double_rq_unlock(rq_src, rq_dest);
5815 * migration_thread - this is a highprio system thread that performs
5816 * thread migration by bumping thread off CPU then 'pushing' onto
5819 static int migration_thread(void *data)
5821 int cpu = (long)data;
5825 BUG_ON(rq->migration_thread != current);
5827 set_current_state(TASK_INTERRUPTIBLE);
5828 while (!kthread_should_stop()) {
5829 struct migration_req *req;
5830 struct list_head *head;
5832 spin_lock_irq(&rq->lock);
5834 if (cpu_is_offline(cpu)) {
5835 spin_unlock_irq(&rq->lock);
5839 if (rq->active_balance) {
5840 active_load_balance(rq, cpu);
5841 rq->active_balance = 0;
5844 head = &rq->migration_queue;
5846 if (list_empty(head)) {
5847 spin_unlock_irq(&rq->lock);
5849 set_current_state(TASK_INTERRUPTIBLE);
5852 req = list_entry(head->next, struct migration_req, list);
5853 list_del_init(head->next);
5855 spin_unlock(&rq->lock);
5856 __migrate_task(req->task, cpu, req->dest_cpu);
5859 complete(&req->done);
5861 __set_current_state(TASK_RUNNING);
5865 /* Wait for kthread_stop */
5866 set_current_state(TASK_INTERRUPTIBLE);
5867 while (!kthread_should_stop()) {
5869 set_current_state(TASK_INTERRUPTIBLE);
5871 __set_current_state(TASK_RUNNING);
5875 #ifdef CONFIG_HOTPLUG_CPU
5877 static int __migrate_task_irq(struct task_struct *p, int src_cpu, int dest_cpu)
5881 local_irq_disable();
5882 ret = __migrate_task(p, src_cpu, dest_cpu);
5888 * Figure out where task on dead CPU should go, use force if necessary.
5889 * NOTE: interrupts should be disabled by the caller
5891 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
5893 unsigned long flags;
5900 mask = node_to_cpumask(cpu_to_node(dead_cpu));
5901 cpus_and(mask, mask, p->cpus_allowed);
5902 dest_cpu = any_online_cpu(mask);
5904 /* On any allowed CPU? */
5905 if (dest_cpu >= nr_cpu_ids)
5906 dest_cpu = any_online_cpu(p->cpus_allowed);
5908 /* No more Mr. Nice Guy. */
5909 if (dest_cpu >= nr_cpu_ids) {
5910 cpumask_t cpus_allowed;
5912 cpuset_cpus_allowed_locked(p, &cpus_allowed);
5914 * Try to stay on the same cpuset, where the
5915 * current cpuset may be a subset of all cpus.
5916 * The cpuset_cpus_allowed_locked() variant of
5917 * cpuset_cpus_allowed() will not block. It must be
5918 * called within calls to cpuset_lock/cpuset_unlock.
5920 rq = task_rq_lock(p, &flags);
5921 p->cpus_allowed = cpus_allowed;
5922 dest_cpu = any_online_cpu(p->cpus_allowed);
5923 task_rq_unlock(rq, &flags);
5926 * Don't tell them about moving exiting tasks or
5927 * kernel threads (both mm NULL), since they never
5930 if (p->mm && printk_ratelimit()) {
5931 printk(KERN_INFO "process %d (%s) no "
5932 "longer affine to cpu%d\n",
5933 task_pid_nr(p), p->comm, dead_cpu);
5936 } while (!__migrate_task_irq(p, dead_cpu, dest_cpu));
5940 * While a dead CPU has no uninterruptible tasks queued at this point,
5941 * it might still have a nonzero ->nr_uninterruptible counter, because
5942 * for performance reasons the counter is not stricly tracking tasks to
5943 * their home CPUs. So we just add the counter to another CPU's counter,
5944 * to keep the global sum constant after CPU-down:
5946 static void migrate_nr_uninterruptible(struct rq *rq_src)
5948 struct rq *rq_dest = cpu_rq(any_online_cpu(*CPU_MASK_ALL_PTR));
5949 unsigned long flags;
5951 local_irq_save(flags);
5952 double_rq_lock(rq_src, rq_dest);
5953 rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
5954 rq_src->nr_uninterruptible = 0;
5955 double_rq_unlock(rq_src, rq_dest);
5956 local_irq_restore(flags);
5959 /* Run through task list and migrate tasks from the dead cpu. */
5960 static void migrate_live_tasks(int src_cpu)
5962 struct task_struct *p, *t;
5964 read_lock(&tasklist_lock);
5966 do_each_thread(t, p) {
5970 if (task_cpu(p) == src_cpu)
5971 move_task_off_dead_cpu(src_cpu, p);
5972 } while_each_thread(t, p);
5974 read_unlock(&tasklist_lock);
5978 * Schedules idle task to be the next runnable task on current CPU.
5979 * It does so by boosting its priority to highest possible.
5980 * Used by CPU offline code.
5982 void sched_idle_next(void)
5984 int this_cpu = smp_processor_id();
5985 struct rq *rq = cpu_rq(this_cpu);
5986 struct task_struct *p = rq->idle;
5987 unsigned long flags;
5989 /* cpu has to be offline */
5990 BUG_ON(cpu_online(this_cpu));
5993 * Strictly not necessary since rest of the CPUs are stopped by now
5994 * and interrupts disabled on the current cpu.
5996 spin_lock_irqsave(&rq->lock, flags);
5998 __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
6000 update_rq_clock(rq);
6001 activate_task(rq, p, 0);
6003 spin_unlock_irqrestore(&rq->lock, flags);
6007 * Ensures that the idle task is using init_mm right before its cpu goes
6010 void idle_task_exit(void)
6012 struct mm_struct *mm = current->active_mm;
6014 BUG_ON(cpu_online(smp_processor_id()));
6017 switch_mm(mm, &init_mm, current);
6021 /* called under rq->lock with disabled interrupts */
6022 static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
6024 struct rq *rq = cpu_rq(dead_cpu);
6026 /* Must be exiting, otherwise would be on tasklist. */
6027 BUG_ON(!p->exit_state);
6029 /* Cannot have done final schedule yet: would have vanished. */
6030 BUG_ON(p->state == TASK_DEAD);
6035 * Drop lock around migration; if someone else moves it,
6036 * that's OK. No task can be added to this CPU, so iteration is
6039 spin_unlock_irq(&rq->lock);
6040 move_task_off_dead_cpu(dead_cpu, p);
6041 spin_lock_irq(&rq->lock);
6046 /* release_task() removes task from tasklist, so we won't find dead tasks. */
6047 static void migrate_dead_tasks(unsigned int dead_cpu)
6049 struct rq *rq = cpu_rq(dead_cpu);
6050 struct task_struct *next;
6053 if (!rq->nr_running)
6055 update_rq_clock(rq);
6056 next = pick_next_task(rq, rq->curr);
6059 migrate_dead(dead_cpu, next);
6063 #endif /* CONFIG_HOTPLUG_CPU */
6065 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
6067 static struct ctl_table sd_ctl_dir[] = {
6069 .procname = "sched_domain",
6075 static struct ctl_table sd_ctl_root[] = {
6077 .ctl_name = CTL_KERN,
6078 .procname = "kernel",
6080 .child = sd_ctl_dir,
6085 static struct ctl_table *sd_alloc_ctl_entry(int n)
6087 struct ctl_table *entry =
6088 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
6093 static void sd_free_ctl_entry(struct ctl_table **tablep)
6095 struct ctl_table *entry;
6098 * In the intermediate directories, both the child directory and
6099 * procname are dynamically allocated and could fail but the mode
6100 * will always be set. In the lowest directory the names are
6101 * static strings and all have proc handlers.
6103 for (entry = *tablep; entry->mode; entry++) {
6105 sd_free_ctl_entry(&entry->child);
6106 if (entry->proc_handler == NULL)
6107 kfree(entry->procname);
6115 set_table_entry(struct ctl_table *entry,
6116 const char *procname, void *data, int maxlen,
6117 mode_t mode, proc_handler *proc_handler)
6119 entry->procname = procname;
6121 entry->maxlen = maxlen;
6123 entry->proc_handler = proc_handler;
6126 static struct ctl_table *
6127 sd_alloc_ctl_domain_table(struct sched_domain *sd)
6129 struct ctl_table *table = sd_alloc_ctl_entry(12);
6134 set_table_entry(&table[0], "min_interval", &sd->min_interval,
6135 sizeof(long), 0644, proc_doulongvec_minmax);
6136 set_table_entry(&table[1], "max_interval", &sd->max_interval,
6137 sizeof(long), 0644, proc_doulongvec_minmax);
6138 set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
6139 sizeof(int), 0644, proc_dointvec_minmax);
6140 set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
6141 sizeof(int), 0644, proc_dointvec_minmax);
6142 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
6143 sizeof(int), 0644, proc_dointvec_minmax);
6144 set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
6145 sizeof(int), 0644, proc_dointvec_minmax);
6146 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
6147 sizeof(int), 0644, proc_dointvec_minmax);
6148 set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
6149 sizeof(int), 0644, proc_dointvec_minmax);
6150 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
6151 sizeof(int), 0644, proc_dointvec_minmax);
6152 set_table_entry(&table[9], "cache_nice_tries",
6153 &sd->cache_nice_tries,
6154 sizeof(int), 0644, proc_dointvec_minmax);
6155 set_table_entry(&table[10], "flags", &sd->flags,
6156 sizeof(int), 0644, proc_dointvec_minmax);
6157 /* &table[11] is terminator */
6162 static ctl_table *sd_alloc_ctl_cpu_table(int cpu)
6164 struct ctl_table *entry, *table;
6165 struct sched_domain *sd;
6166 int domain_num = 0, i;
6169 for_each_domain(cpu, sd)
6171 entry = table = sd_alloc_ctl_entry(domain_num + 1);
6176 for_each_domain(cpu, sd) {
6177 snprintf(buf, 32, "domain%d", i);
6178 entry->procname = kstrdup(buf, GFP_KERNEL);
6180 entry->child = sd_alloc_ctl_domain_table(sd);
6187 static struct ctl_table_header *sd_sysctl_header;
6188 static void register_sched_domain_sysctl(void)
6190 int i, cpu_num = num_online_cpus();
6191 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
6194 WARN_ON(sd_ctl_dir[0].child);
6195 sd_ctl_dir[0].child = entry;
6200 for_each_online_cpu(i) {
6201 snprintf(buf, 32, "cpu%d", i);
6202 entry->procname = kstrdup(buf, GFP_KERNEL);
6204 entry->child = sd_alloc_ctl_cpu_table(i);
6208 WARN_ON(sd_sysctl_header);
6209 sd_sysctl_header = register_sysctl_table(sd_ctl_root);
6212 /* may be called multiple times per register */
6213 static void unregister_sched_domain_sysctl(void)
6215 if (sd_sysctl_header)
6216 unregister_sysctl_table(sd_sysctl_header);
6217 sd_sysctl_header = NULL;
6218 if (sd_ctl_dir[0].child)
6219 sd_free_ctl_entry(&sd_ctl_dir[0].child);
6222 static void register_sched_domain_sysctl(void)
6225 static void unregister_sched_domain_sysctl(void)
6230 static void set_rq_online(struct rq *rq)
6233 const struct sched_class *class;
6235 cpu_set(rq->cpu, rq->rd->online);
6238 for_each_class(class) {
6239 if (class->rq_online)
6240 class->rq_online(rq);
6245 static void set_rq_offline(struct rq *rq)
6248 const struct sched_class *class;
6250 for_each_class(class) {
6251 if (class->rq_offline)
6252 class->rq_offline(rq);
6255 cpu_clear(rq->cpu, rq->rd->online);
6261 * migration_call - callback that gets triggered when a CPU is added.
6262 * Here we can start up the necessary migration thread for the new CPU.
6264 static int __cpuinit
6265 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
6267 struct task_struct *p;
6268 int cpu = (long)hcpu;
6269 unsigned long flags;
6274 case CPU_UP_PREPARE:
6275 case CPU_UP_PREPARE_FROZEN:
6276 p = kthread_create(migration_thread, hcpu, "migration/%d", cpu);
6279 kthread_bind(p, cpu);
6280 /* Must be high prio: stop_machine expects to yield to it. */
6281 rq = task_rq_lock(p, &flags);
6282 __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
6283 task_rq_unlock(rq, &flags);
6284 cpu_rq(cpu)->migration_thread = p;
6288 case CPU_ONLINE_FROZEN:
6289 /* Strictly unnecessary, as first user will wake it. */
6290 wake_up_process(cpu_rq(cpu)->migration_thread);
6292 /* Update our root-domain */
6294 spin_lock_irqsave(&rq->lock, flags);
6296 BUG_ON(!cpu_isset(cpu, rq->rd->span));
6300 spin_unlock_irqrestore(&rq->lock, flags);
6303 #ifdef CONFIG_HOTPLUG_CPU
6304 case CPU_UP_CANCELED:
6305 case CPU_UP_CANCELED_FROZEN:
6306 if (!cpu_rq(cpu)->migration_thread)
6308 /* Unbind it from offline cpu so it can run. Fall thru. */
6309 kthread_bind(cpu_rq(cpu)->migration_thread,
6310 any_online_cpu(cpu_online_map));
6311 kthread_stop(cpu_rq(cpu)->migration_thread);
6312 cpu_rq(cpu)->migration_thread = NULL;
6316 case CPU_DEAD_FROZEN:
6317 cpuset_lock(); /* around calls to cpuset_cpus_allowed_lock() */
6318 migrate_live_tasks(cpu);
6320 kthread_stop(rq->migration_thread);
6321 rq->migration_thread = NULL;
6322 /* Idle task back to normal (off runqueue, low prio) */
6323 spin_lock_irq(&rq->lock);
6324 update_rq_clock(rq);
6325 deactivate_task(rq, rq->idle, 0);
6326 rq->idle->static_prio = MAX_PRIO;
6327 __setscheduler(rq, rq->idle, SCHED_NORMAL, 0);
6328 rq->idle->sched_class = &idle_sched_class;
6329 migrate_dead_tasks(cpu);
6330 spin_unlock_irq(&rq->lock);
6332 migrate_nr_uninterruptible(rq);
6333 BUG_ON(rq->nr_running != 0);
6336 * No need to migrate the tasks: it was best-effort if
6337 * they didn't take sched_hotcpu_mutex. Just wake up
6340 spin_lock_irq(&rq->lock);
6341 while (!list_empty(&rq->migration_queue)) {
6342 struct migration_req *req;
6344 req = list_entry(rq->migration_queue.next,
6345 struct migration_req, list);
6346 list_del_init(&req->list);
6347 complete(&req->done);
6349 spin_unlock_irq(&rq->lock);
6353 case CPU_DYING_FROZEN:
6354 /* Update our root-domain */
6356 spin_lock_irqsave(&rq->lock, flags);
6358 BUG_ON(!cpu_isset(cpu, rq->rd->span));
6361 spin_unlock_irqrestore(&rq->lock, flags);
6368 /* Register at highest priority so that task migration (migrate_all_tasks)
6369 * happens before everything else.
6371 static struct notifier_block __cpuinitdata migration_notifier = {
6372 .notifier_call = migration_call,
6376 void __init migration_init(void)
6378 void *cpu = (void *)(long)smp_processor_id();
6381 /* Start one for the boot CPU: */
6382 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
6383 BUG_ON(err == NOTIFY_BAD);
6384 migration_call(&migration_notifier, CPU_ONLINE, cpu);
6385 register_cpu_notifier(&migration_notifier);
6391 #ifdef CONFIG_SCHED_DEBUG
6393 static inline const char *sd_level_to_string(enum sched_domain_level lvl)
6406 case SD_LV_ALLNODES:
6415 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
6416 cpumask_t *groupmask)
6418 struct sched_group *group = sd->groups;
6421 cpulist_scnprintf(str, sizeof(str), sd->span);
6422 cpus_clear(*groupmask);
6424 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
6426 if (!(sd->flags & SD_LOAD_BALANCE)) {
6427 printk("does not load-balance\n");
6429 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
6434 printk(KERN_CONT "span %s level %s\n",
6435 str, sd_level_to_string(sd->level));
6437 if (!cpu_isset(cpu, sd->span)) {
6438 printk(KERN_ERR "ERROR: domain->span does not contain "
6441 if (!cpu_isset(cpu, group->cpumask)) {
6442 printk(KERN_ERR "ERROR: domain->groups does not contain"
6446 printk(KERN_DEBUG "%*s groups:", level + 1, "");
6450 printk(KERN_ERR "ERROR: group is NULL\n");
6454 if (!group->__cpu_power) {
6455 printk(KERN_CONT "\n");
6456 printk(KERN_ERR "ERROR: domain->cpu_power not "
6461 if (!cpus_weight(group->cpumask)) {
6462 printk(KERN_CONT "\n");
6463 printk(KERN_ERR "ERROR: empty group\n");
6467 if (cpus_intersects(*groupmask, group->cpumask)) {
6468 printk(KERN_CONT "\n");
6469 printk(KERN_ERR "ERROR: repeated CPUs\n");
6473 cpus_or(*groupmask, *groupmask, group->cpumask);
6475 cpulist_scnprintf(str, sizeof(str), group->cpumask);
6476 printk(KERN_CONT " %s", str);
6478 group = group->next;
6479 } while (group != sd->groups);
6480 printk(KERN_CONT "\n");
6482 if (!cpus_equal(sd->span, *groupmask))
6483 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
6485 if (sd->parent && !cpus_subset(*groupmask, sd->parent->span))
6486 printk(KERN_ERR "ERROR: parent span is not a superset "
6487 "of domain->span\n");
6491 static void sched_domain_debug(struct sched_domain *sd, int cpu)
6493 cpumask_t *groupmask;
6497 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
6501 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
6503 groupmask = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
6505 printk(KERN_DEBUG "Cannot load-balance (out of memory)\n");
6510 if (sched_domain_debug_one(sd, cpu, level, groupmask))
6519 #else /* !CONFIG_SCHED_DEBUG */
6520 # define sched_domain_debug(sd, cpu) do { } while (0)
6521 #endif /* CONFIG_SCHED_DEBUG */
6523 static int sd_degenerate(struct sched_domain *sd)
6525 if (cpus_weight(sd->span) == 1)
6528 /* Following flags need at least 2 groups */
6529 if (sd->flags & (SD_LOAD_BALANCE |
6530 SD_BALANCE_NEWIDLE |
6534 SD_SHARE_PKG_RESOURCES)) {
6535 if (sd->groups != sd->groups->next)
6539 /* Following flags don't use groups */
6540 if (sd->flags & (SD_WAKE_IDLE |
6549 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
6551 unsigned long cflags = sd->flags, pflags = parent->flags;
6553 if (sd_degenerate(parent))
6556 if (!cpus_equal(sd->span, parent->span))
6559 /* Does parent contain flags not in child? */
6560 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
6561 if (cflags & SD_WAKE_AFFINE)
6562 pflags &= ~SD_WAKE_BALANCE;
6563 /* Flags needing groups don't count if only 1 group in parent */
6564 if (parent->groups == parent->groups->next) {
6565 pflags &= ~(SD_LOAD_BALANCE |
6566 SD_BALANCE_NEWIDLE |
6570 SD_SHARE_PKG_RESOURCES);
6572 if (~cflags & pflags)
6578 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
6580 unsigned long flags;
6582 spin_lock_irqsave(&rq->lock, flags);
6585 struct root_domain *old_rd = rq->rd;
6587 if (cpu_isset(rq->cpu, old_rd->online))
6590 cpu_clear(rq->cpu, old_rd->span);
6592 if (atomic_dec_and_test(&old_rd->refcount))
6596 atomic_inc(&rd->refcount);
6599 cpu_set(rq->cpu, rd->span);
6600 if (cpu_isset(rq->cpu, cpu_online_map))
6603 spin_unlock_irqrestore(&rq->lock, flags);
6606 static void init_rootdomain(struct root_domain *rd)
6608 memset(rd, 0, sizeof(*rd));
6610 cpus_clear(rd->span);
6611 cpus_clear(rd->online);
6613 cpupri_init(&rd->cpupri);
6616 static void init_defrootdomain(void)
6618 init_rootdomain(&def_root_domain);
6619 atomic_set(&def_root_domain.refcount, 1);
6622 static struct root_domain *alloc_rootdomain(void)
6624 struct root_domain *rd;
6626 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
6630 init_rootdomain(rd);
6636 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
6637 * hold the hotplug lock.
6640 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
6642 struct rq *rq = cpu_rq(cpu);
6643 struct sched_domain *tmp;
6645 /* Remove the sched domains which do not contribute to scheduling. */
6646 for (tmp = sd; tmp; tmp = tmp->parent) {
6647 struct sched_domain *parent = tmp->parent;
6650 if (sd_parent_degenerate(tmp, parent)) {
6651 tmp->parent = parent->parent;
6653 parent->parent->child = tmp;
6657 if (sd && sd_degenerate(sd)) {
6663 sched_domain_debug(sd, cpu);
6665 rq_attach_root(rq, rd);
6666 rcu_assign_pointer(rq->sd, sd);
6669 /* cpus with isolated domains */
6670 static cpumask_t cpu_isolated_map = CPU_MASK_NONE;
6672 /* Setup the mask of cpus configured for isolated domains */
6673 static int __init isolated_cpu_setup(char *str)
6675 int ints[NR_CPUS], i;
6677 str = get_options(str, ARRAY_SIZE(ints), ints);
6678 cpus_clear(cpu_isolated_map);
6679 for (i = 1; i <= ints[0]; i++)
6680 if (ints[i] < NR_CPUS)
6681 cpu_set(ints[i], cpu_isolated_map);
6685 __setup("isolcpus=", isolated_cpu_setup);
6688 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
6689 * to a function which identifies what group(along with sched group) a CPU
6690 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
6691 * (due to the fact that we keep track of groups covered with a cpumask_t).
6693 * init_sched_build_groups will build a circular linked list of the groups
6694 * covered by the given span, and will set each group's ->cpumask correctly,
6695 * and ->cpu_power to 0.
6698 init_sched_build_groups(const cpumask_t *span, const cpumask_t *cpu_map,
6699 int (*group_fn)(int cpu, const cpumask_t *cpu_map,
6700 struct sched_group **sg,
6701 cpumask_t *tmpmask),
6702 cpumask_t *covered, cpumask_t *tmpmask)
6704 struct sched_group *first = NULL, *last = NULL;
6707 cpus_clear(*covered);
6709 for_each_cpu_mask(i, *span) {
6710 struct sched_group *sg;
6711 int group = group_fn(i, cpu_map, &sg, tmpmask);
6714 if (cpu_isset(i, *covered))
6717 cpus_clear(sg->cpumask);
6718 sg->__cpu_power = 0;
6720 for_each_cpu_mask(j, *span) {
6721 if (group_fn(j, cpu_map, NULL, tmpmask) != group)
6724 cpu_set(j, *covered);
6725 cpu_set(j, sg->cpumask);
6736 #define SD_NODES_PER_DOMAIN 16
6741 * find_next_best_node - find the next node to include in a sched_domain
6742 * @node: node whose sched_domain we're building
6743 * @used_nodes: nodes already in the sched_domain
6745 * Find the next node to include in a given scheduling domain. Simply
6746 * finds the closest node not already in the @used_nodes map.
6748 * Should use nodemask_t.
6750 static int find_next_best_node(int node, nodemask_t *used_nodes)
6752 int i, n, val, min_val, best_node = 0;
6756 for (i = 0; i < MAX_NUMNODES; i++) {
6757 /* Start at @node */
6758 n = (node + i) % MAX_NUMNODES;
6760 if (!nr_cpus_node(n))
6763 /* Skip already used nodes */
6764 if (node_isset(n, *used_nodes))
6767 /* Simple min distance search */
6768 val = node_distance(node, n);
6770 if (val < min_val) {
6776 node_set(best_node, *used_nodes);
6781 * sched_domain_node_span - get a cpumask for a node's sched_domain
6782 * @node: node whose cpumask we're constructing
6783 * @span: resulting cpumask
6785 * Given a node, construct a good cpumask for its sched_domain to span. It
6786 * should be one that prevents unnecessary balancing, but also spreads tasks
6789 static void sched_domain_node_span(int node, cpumask_t *span)
6791 nodemask_t used_nodes;
6792 node_to_cpumask_ptr(nodemask, node);
6796 nodes_clear(used_nodes);
6798 cpus_or(*span, *span, *nodemask);
6799 node_set(node, used_nodes);
6801 for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
6802 int next_node = find_next_best_node(node, &used_nodes);
6804 node_to_cpumask_ptr_next(nodemask, next_node);
6805 cpus_or(*span, *span, *nodemask);
6808 #endif /* CONFIG_NUMA */
6810 int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
6813 * SMT sched-domains:
6815 #ifdef CONFIG_SCHED_SMT
6816 static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
6817 static DEFINE_PER_CPU(struct sched_group, sched_group_cpus);
6820 cpu_to_cpu_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg,
6824 *sg = &per_cpu(sched_group_cpus, cpu);
6827 #endif /* CONFIG_SCHED_SMT */
6830 * multi-core sched-domains:
6832 #ifdef CONFIG_SCHED_MC
6833 static DEFINE_PER_CPU(struct sched_domain, core_domains);
6834 static DEFINE_PER_CPU(struct sched_group, sched_group_core);
6835 #endif /* CONFIG_SCHED_MC */
6837 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6839 cpu_to_core_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg,
6844 *mask = per_cpu(cpu_sibling_map, cpu);
6845 cpus_and(*mask, *mask, *cpu_map);
6846 group = first_cpu(*mask);
6848 *sg = &per_cpu(sched_group_core, group);
6851 #elif defined(CONFIG_SCHED_MC)
6853 cpu_to_core_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg,
6857 *sg = &per_cpu(sched_group_core, cpu);
6862 static DEFINE_PER_CPU(struct sched_domain, phys_domains);
6863 static DEFINE_PER_CPU(struct sched_group, sched_group_phys);
6866 cpu_to_phys_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg,
6870 #ifdef CONFIG_SCHED_MC
6871 *mask = cpu_coregroup_map(cpu);
6872 cpus_and(*mask, *mask, *cpu_map);
6873 group = first_cpu(*mask);
6874 #elif defined(CONFIG_SCHED_SMT)
6875 *mask = per_cpu(cpu_sibling_map, cpu);
6876 cpus_and(*mask, *mask, *cpu_map);
6877 group = first_cpu(*mask);
6882 *sg = &per_cpu(sched_group_phys, group);
6888 * The init_sched_build_groups can't handle what we want to do with node
6889 * groups, so roll our own. Now each node has its own list of groups which
6890 * gets dynamically allocated.
6892 static DEFINE_PER_CPU(struct sched_domain, node_domains);
6893 static struct sched_group ***sched_group_nodes_bycpu;
6895 static DEFINE_PER_CPU(struct sched_domain, allnodes_domains);
6896 static DEFINE_PER_CPU(struct sched_group, sched_group_allnodes);
6898 static int cpu_to_allnodes_group(int cpu, const cpumask_t *cpu_map,
6899 struct sched_group **sg, cpumask_t *nodemask)
6903 *nodemask = node_to_cpumask(cpu_to_node(cpu));
6904 cpus_and(*nodemask, *nodemask, *cpu_map);
6905 group = first_cpu(*nodemask);
6908 *sg = &per_cpu(sched_group_allnodes, group);
6912 static void init_numa_sched_groups_power(struct sched_group *group_head)
6914 struct sched_group *sg = group_head;
6920 for_each_cpu_mask(j, sg->cpumask) {
6921 struct sched_domain *sd;
6923 sd = &per_cpu(phys_domains, j);
6924 if (j != first_cpu(sd->groups->cpumask)) {
6926 * Only add "power" once for each
6932 sg_inc_cpu_power(sg, sd->groups->__cpu_power);
6935 } while (sg != group_head);
6937 #endif /* CONFIG_NUMA */
6940 /* Free memory allocated for various sched_group structures */
6941 static void free_sched_groups(const cpumask_t *cpu_map, cpumask_t *nodemask)
6945 for_each_cpu_mask(cpu, *cpu_map) {
6946 struct sched_group **sched_group_nodes
6947 = sched_group_nodes_bycpu[cpu];
6949 if (!sched_group_nodes)
6952 for (i = 0; i < MAX_NUMNODES; i++) {
6953 struct sched_group *oldsg, *sg = sched_group_nodes[i];
6955 *nodemask = node_to_cpumask(i);
6956 cpus_and(*nodemask, *nodemask, *cpu_map);
6957 if (cpus_empty(*nodemask))
6967 if (oldsg != sched_group_nodes[i])
6970 kfree(sched_group_nodes);
6971 sched_group_nodes_bycpu[cpu] = NULL;
6974 #else /* !CONFIG_NUMA */
6975 static void free_sched_groups(const cpumask_t *cpu_map, cpumask_t *nodemask)
6978 #endif /* CONFIG_NUMA */
6981 * Initialize sched groups cpu_power.
6983 * cpu_power indicates the capacity of sched group, which is used while
6984 * distributing the load between different sched groups in a sched domain.
6985 * Typically cpu_power for all the groups in a sched domain will be same unless
6986 * there are asymmetries in the topology. If there are asymmetries, group
6987 * having more cpu_power will pickup more load compared to the group having
6990 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
6991 * the maximum number of tasks a group can handle in the presence of other idle
6992 * or lightly loaded groups in the same sched domain.
6994 static void init_sched_groups_power(int cpu, struct sched_domain *sd)
6996 struct sched_domain *child;
6997 struct sched_group *group;
6999 WARN_ON(!sd || !sd->groups);
7001 if (cpu != first_cpu(sd->groups->cpumask))
7006 sd->groups->__cpu_power = 0;
7009 * For perf policy, if the groups in child domain share resources
7010 * (for example cores sharing some portions of the cache hierarchy
7011 * or SMT), then set this domain groups cpu_power such that each group
7012 * can handle only one task, when there are other idle groups in the
7013 * same sched domain.
7015 if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) &&
7017 (SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) {
7018 sg_inc_cpu_power(sd->groups, SCHED_LOAD_SCALE);
7023 * add cpu_power of each child group to this groups cpu_power
7025 group = child->groups;
7027 sg_inc_cpu_power(sd->groups, group->__cpu_power);
7028 group = group->next;
7029 } while (group != child->groups);
7033 * Initializers for schedule domains
7034 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
7037 #define SD_INIT(sd, type) sd_init_##type(sd)
7038 #define SD_INIT_FUNC(type) \
7039 static noinline void sd_init_##type(struct sched_domain *sd) \
7041 memset(sd, 0, sizeof(*sd)); \
7042 *sd = SD_##type##_INIT; \
7043 sd->level = SD_LV_##type; \
7048 SD_INIT_FUNC(ALLNODES)
7051 #ifdef CONFIG_SCHED_SMT
7052 SD_INIT_FUNC(SIBLING)
7054 #ifdef CONFIG_SCHED_MC
7059 * To minimize stack usage kmalloc room for cpumasks and share the
7060 * space as the usage in build_sched_domains() dictates. Used only
7061 * if the amount of space is significant.
7064 cpumask_t tmpmask; /* make this one first */
7067 cpumask_t this_sibling_map;
7068 cpumask_t this_core_map;
7070 cpumask_t send_covered;
7073 cpumask_t domainspan;
7075 cpumask_t notcovered;
7080 #define SCHED_CPUMASK_ALLOC 1
7081 #define SCHED_CPUMASK_FREE(v) kfree(v)
7082 #define SCHED_CPUMASK_DECLARE(v) struct allmasks *v
7084 #define SCHED_CPUMASK_ALLOC 0
7085 #define SCHED_CPUMASK_FREE(v)
7086 #define SCHED_CPUMASK_DECLARE(v) struct allmasks _v, *v = &_v
7089 #define SCHED_CPUMASK_VAR(v, a) cpumask_t *v = (cpumask_t *) \
7090 ((unsigned long)(a) + offsetof(struct allmasks, v))
7092 static int default_relax_domain_level = -1;
7094 static int __init setup_relax_domain_level(char *str)
7098 val = simple_strtoul(str, NULL, 0);
7099 if (val < SD_LV_MAX)
7100 default_relax_domain_level = val;
7104 __setup("relax_domain_level=", setup_relax_domain_level);
7106 static void set_domain_attribute(struct sched_domain *sd,
7107 struct sched_domain_attr *attr)
7111 if (!attr || attr->relax_domain_level < 0) {
7112 if (default_relax_domain_level < 0)
7115 request = default_relax_domain_level;
7117 request = attr->relax_domain_level;
7118 if (request < sd->level) {
7119 /* turn off idle balance on this domain */
7120 sd->flags &= ~(SD_WAKE_IDLE|SD_BALANCE_NEWIDLE);
7122 /* turn on idle balance on this domain */
7123 sd->flags |= (SD_WAKE_IDLE_FAR|SD_BALANCE_NEWIDLE);
7128 * Build sched domains for a given set of cpus and attach the sched domains
7129 * to the individual cpus
7131 static int __build_sched_domains(const cpumask_t *cpu_map,
7132 struct sched_domain_attr *attr)
7135 struct root_domain *rd;
7136 SCHED_CPUMASK_DECLARE(allmasks);
7139 struct sched_group **sched_group_nodes = NULL;
7140 int sd_allnodes = 0;
7143 * Allocate the per-node list of sched groups
7145 sched_group_nodes = kcalloc(MAX_NUMNODES, sizeof(struct sched_group *),
7147 if (!sched_group_nodes) {
7148 printk(KERN_WARNING "Can not alloc sched group node list\n");
7153 rd = alloc_rootdomain();
7155 printk(KERN_WARNING "Cannot alloc root domain\n");
7157 kfree(sched_group_nodes);
7162 #if SCHED_CPUMASK_ALLOC
7163 /* get space for all scratch cpumask variables */
7164 allmasks = kmalloc(sizeof(*allmasks), GFP_KERNEL);
7166 printk(KERN_WARNING "Cannot alloc cpumask array\n");
7169 kfree(sched_group_nodes);
7174 tmpmask = (cpumask_t *)allmasks;
7178 sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes;
7182 * Set up domains for cpus specified by the cpu_map.
7184 for_each_cpu_mask(i, *cpu_map) {
7185 struct sched_domain *sd = NULL, *p;
7186 SCHED_CPUMASK_VAR(nodemask, allmasks);
7188 *nodemask = node_to_cpumask(cpu_to_node(i));
7189 cpus_and(*nodemask, *nodemask, *cpu_map);
7192 if (cpus_weight(*cpu_map) >
7193 SD_NODES_PER_DOMAIN*cpus_weight(*nodemask)) {
7194 sd = &per_cpu(allnodes_domains, i);
7195 SD_INIT(sd, ALLNODES);
7196 set_domain_attribute(sd, attr);
7197 sd->span = *cpu_map;
7198 cpu_to_allnodes_group(i, cpu_map, &sd->groups, tmpmask);
7204 sd = &per_cpu(node_domains, i);
7206 set_domain_attribute(sd, attr);
7207 sched_domain_node_span(cpu_to_node(i), &sd->span);
7211 cpus_and(sd->span, sd->span, *cpu_map);
7215 sd = &per_cpu(phys_domains, i);
7217 set_domain_attribute(sd, attr);
7218 sd->span = *nodemask;
7222 cpu_to_phys_group(i, cpu_map, &sd->groups, tmpmask);
7224 #ifdef CONFIG_SCHED_MC
7226 sd = &per_cpu(core_domains, i);
7228 set_domain_attribute(sd, attr);
7229 sd->span = cpu_coregroup_map(i);
7230 cpus_and(sd->span, sd->span, *cpu_map);
7233 cpu_to_core_group(i, cpu_map, &sd->groups, tmpmask);
7236 #ifdef CONFIG_SCHED_SMT
7238 sd = &per_cpu(cpu_domains, i);
7239 SD_INIT(sd, SIBLING);
7240 set_domain_attribute(sd, attr);
7241 sd->span = per_cpu(cpu_sibling_map, i);
7242 cpus_and(sd->span, sd->span, *cpu_map);
7245 cpu_to_cpu_group(i, cpu_map, &sd->groups, tmpmask);
7249 #ifdef CONFIG_SCHED_SMT
7250 /* Set up CPU (sibling) groups */
7251 for_each_cpu_mask(i, *cpu_map) {
7252 SCHED_CPUMASK_VAR(this_sibling_map, allmasks);
7253 SCHED_CPUMASK_VAR(send_covered, allmasks);
7255 *this_sibling_map = per_cpu(cpu_sibling_map, i);
7256 cpus_and(*this_sibling_map, *this_sibling_map, *cpu_map);
7257 if (i != first_cpu(*this_sibling_map))
7260 init_sched_build_groups(this_sibling_map, cpu_map,
7262 send_covered, tmpmask);
7266 #ifdef CONFIG_SCHED_MC
7267 /* Set up multi-core groups */
7268 for_each_cpu_mask(i, *cpu_map) {
7269 SCHED_CPUMASK_VAR(this_core_map, allmasks);
7270 SCHED_CPUMASK_VAR(send_covered, allmasks);
7272 *this_core_map = cpu_coregroup_map(i);
7273 cpus_and(*this_core_map, *this_core_map, *cpu_map);
7274 if (i != first_cpu(*this_core_map))
7277 init_sched_build_groups(this_core_map, cpu_map,
7279 send_covered, tmpmask);
7283 /* Set up physical groups */
7284 for (i = 0; i < MAX_NUMNODES; i++) {
7285 SCHED_CPUMASK_VAR(nodemask, allmasks);
7286 SCHED_CPUMASK_VAR(send_covered, allmasks);
7288 *nodemask = node_to_cpumask(i);
7289 cpus_and(*nodemask, *nodemask, *cpu_map);
7290 if (cpus_empty(*nodemask))
7293 init_sched_build_groups(nodemask, cpu_map,
7295 send_covered, tmpmask);
7299 /* Set up node groups */
7301 SCHED_CPUMASK_VAR(send_covered, allmasks);
7303 init_sched_build_groups(cpu_map, cpu_map,
7304 &cpu_to_allnodes_group,
7305 send_covered, tmpmask);
7308 for (i = 0; i < MAX_NUMNODES; i++) {
7309 /* Set up node groups */
7310 struct sched_group *sg, *prev;
7311 SCHED_CPUMASK_VAR(nodemask, allmasks);
7312 SCHED_CPUMASK_VAR(domainspan, allmasks);
7313 SCHED_CPUMASK_VAR(covered, allmasks);
7316 *nodemask = node_to_cpumask(i);
7317 cpus_clear(*covered);
7319 cpus_and(*nodemask, *nodemask, *cpu_map);
7320 if (cpus_empty(*nodemask)) {
7321 sched_group_nodes[i] = NULL;
7325 sched_domain_node_span(i, domainspan);
7326 cpus_and(*domainspan, *domainspan, *cpu_map);
7328 sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i);
7330 printk(KERN_WARNING "Can not alloc domain group for "
7334 sched_group_nodes[i] = sg;
7335 for_each_cpu_mask(j, *nodemask) {
7336 struct sched_domain *sd;
7338 sd = &per_cpu(node_domains, j);
7341 sg->__cpu_power = 0;
7342 sg->cpumask = *nodemask;
7344 cpus_or(*covered, *covered, *nodemask);
7347 for (j = 0; j < MAX_NUMNODES; j++) {
7348 SCHED_CPUMASK_VAR(notcovered, allmasks);
7349 int n = (i + j) % MAX_NUMNODES;
7350 node_to_cpumask_ptr(pnodemask, n);
7352 cpus_complement(*notcovered, *covered);
7353 cpus_and(*tmpmask, *notcovered, *cpu_map);
7354 cpus_and(*tmpmask, *tmpmask, *domainspan);
7355 if (cpus_empty(*tmpmask))
7358 cpus_and(*tmpmask, *tmpmask, *pnodemask);
7359 if (cpus_empty(*tmpmask))
7362 sg = kmalloc_node(sizeof(struct sched_group),
7366 "Can not alloc domain group for node %d\n", j);
7369 sg->__cpu_power = 0;
7370 sg->cpumask = *tmpmask;
7371 sg->next = prev->next;
7372 cpus_or(*covered, *covered, *tmpmask);
7379 /* Calculate CPU power for physical packages and nodes */
7380 #ifdef CONFIG_SCHED_SMT
7381 for_each_cpu_mask(i, *cpu_map) {
7382 struct sched_domain *sd = &per_cpu(cpu_domains, i);
7384 init_sched_groups_power(i, sd);
7387 #ifdef CONFIG_SCHED_MC
7388 for_each_cpu_mask(i, *cpu_map) {
7389 struct sched_domain *sd = &per_cpu(core_domains, i);
7391 init_sched_groups_power(i, sd);
7395 for_each_cpu_mask(i, *cpu_map) {
7396 struct sched_domain *sd = &per_cpu(phys_domains, i);
7398 init_sched_groups_power(i, sd);
7402 for (i = 0; i < MAX_NUMNODES; i++)
7403 init_numa_sched_groups_power(sched_group_nodes[i]);
7406 struct sched_group *sg;
7408 cpu_to_allnodes_group(first_cpu(*cpu_map), cpu_map, &sg,
7410 init_numa_sched_groups_power(sg);
7414 /* Attach the domains */
7415 for_each_cpu_mask(i, *cpu_map) {
7416 struct sched_domain *sd;
7417 #ifdef CONFIG_SCHED_SMT
7418 sd = &per_cpu(cpu_domains, i);
7419 #elif defined(CONFIG_SCHED_MC)
7420 sd = &per_cpu(core_domains, i);
7422 sd = &per_cpu(phys_domains, i);
7424 cpu_attach_domain(sd, rd, i);
7427 SCHED_CPUMASK_FREE((void *)allmasks);
7432 free_sched_groups(cpu_map, tmpmask);
7433 SCHED_CPUMASK_FREE((void *)allmasks);
7438 static int build_sched_domains(const cpumask_t *cpu_map)
7440 return __build_sched_domains(cpu_map, NULL);
7443 static cpumask_t *doms_cur; /* current sched domains */
7444 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
7445 static struct sched_domain_attr *dattr_cur;
7446 /* attribues of custom domains in 'doms_cur' */
7449 * Special case: If a kmalloc of a doms_cur partition (array of
7450 * cpumask_t) fails, then fallback to a single sched domain,
7451 * as determined by the single cpumask_t fallback_doms.
7453 static cpumask_t fallback_doms;
7455 void __attribute__((weak)) arch_update_cpu_topology(void)
7460 * Free current domain masks.
7461 * Called after all cpus are attached to NULL domain.
7463 static void free_sched_domains(void)
7466 if (doms_cur != &fallback_doms)
7468 doms_cur = &fallback_doms;
7472 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
7473 * For now this just excludes isolated cpus, but could be used to
7474 * exclude other special cases in the future.
7476 static int arch_init_sched_domains(const cpumask_t *cpu_map)
7480 arch_update_cpu_topology();
7482 doms_cur = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
7484 doms_cur = &fallback_doms;
7485 cpus_andnot(*doms_cur, *cpu_map, cpu_isolated_map);
7487 err = build_sched_domains(doms_cur);
7488 register_sched_domain_sysctl();
7493 static void arch_destroy_sched_domains(const cpumask_t *cpu_map,
7496 free_sched_groups(cpu_map, tmpmask);
7500 * Detach sched domains from a group of cpus specified in cpu_map
7501 * These cpus will now be attached to the NULL domain
7503 static void detach_destroy_domains(const cpumask_t *cpu_map)
7508 unregister_sched_domain_sysctl();
7510 for_each_cpu_mask(i, *cpu_map)
7511 cpu_attach_domain(NULL, &def_root_domain, i);
7512 synchronize_sched();
7513 arch_destroy_sched_domains(cpu_map, &tmpmask);
7516 /* handle null as "default" */
7517 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
7518 struct sched_domain_attr *new, int idx_new)
7520 struct sched_domain_attr tmp;
7527 return !memcmp(cur ? (cur + idx_cur) : &tmp,
7528 new ? (new + idx_new) : &tmp,
7529 sizeof(struct sched_domain_attr));
7533 * Partition sched domains as specified by the 'ndoms_new'
7534 * cpumasks in the array doms_new[] of cpumasks. This compares
7535 * doms_new[] to the current sched domain partitioning, doms_cur[].
7536 * It destroys each deleted domain and builds each new domain.
7538 * 'doms_new' is an array of cpumask_t's of length 'ndoms_new'.
7539 * The masks don't intersect (don't overlap.) We should setup one
7540 * sched domain for each mask. CPUs not in any of the cpumasks will
7541 * not be load balanced. If the same cpumask appears both in the
7542 * current 'doms_cur' domains and in the new 'doms_new', we can leave
7545 * The passed in 'doms_new' should be kmalloc'd. This routine takes
7546 * ownership of it and will kfree it when done with it. If the caller
7547 * failed the kmalloc call, then it can pass in doms_new == NULL,
7548 * and partition_sched_domains() will fallback to the single partition
7551 * Call with hotplug lock held
7553 void partition_sched_domains(int ndoms_new, cpumask_t *doms_new,
7554 struct sched_domain_attr *dattr_new)
7558 mutex_lock(&sched_domains_mutex);
7560 /* always unregister in case we don't destroy any domains */
7561 unregister_sched_domain_sysctl();
7563 if (doms_new == NULL) {
7565 doms_new = &fallback_doms;
7566 cpus_andnot(doms_new[0], cpu_online_map, cpu_isolated_map);
7570 /* Destroy deleted domains */
7571 for (i = 0; i < ndoms_cur; i++) {
7572 for (j = 0; j < ndoms_new; j++) {
7573 if (cpus_equal(doms_cur[i], doms_new[j])
7574 && dattrs_equal(dattr_cur, i, dattr_new, j))
7577 /* no match - a current sched domain not in new doms_new[] */
7578 detach_destroy_domains(doms_cur + i);
7583 /* Build new domains */
7584 for (i = 0; i < ndoms_new; i++) {
7585 for (j = 0; j < ndoms_cur; j++) {
7586 if (cpus_equal(doms_new[i], doms_cur[j])
7587 && dattrs_equal(dattr_new, i, dattr_cur, j))
7590 /* no match - add a new doms_new */
7591 __build_sched_domains(doms_new + i,
7592 dattr_new ? dattr_new + i : NULL);
7597 /* Remember the new sched domains */
7598 if (doms_cur != &fallback_doms)
7600 kfree(dattr_cur); /* kfree(NULL) is safe */
7601 doms_cur = doms_new;
7602 dattr_cur = dattr_new;
7603 ndoms_cur = ndoms_new;
7605 register_sched_domain_sysctl();
7607 mutex_unlock(&sched_domains_mutex);
7610 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
7611 int arch_reinit_sched_domains(void)
7616 mutex_lock(&sched_domains_mutex);
7617 detach_destroy_domains(&cpu_online_map);
7618 free_sched_domains();
7619 err = arch_init_sched_domains(&cpu_online_map);
7620 mutex_unlock(&sched_domains_mutex);
7626 static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
7630 if (buf[0] != '0' && buf[0] != '1')
7634 sched_smt_power_savings = (buf[0] == '1');
7636 sched_mc_power_savings = (buf[0] == '1');
7638 ret = arch_reinit_sched_domains();
7640 return ret ? ret : count;
7643 #ifdef CONFIG_SCHED_MC
7644 static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page)
7646 return sprintf(page, "%u\n", sched_mc_power_savings);
7648 static ssize_t sched_mc_power_savings_store(struct sys_device *dev,
7649 const char *buf, size_t count)
7651 return sched_power_savings_store(buf, count, 0);
7653 static SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
7654 sched_mc_power_savings_store);
7657 #ifdef CONFIG_SCHED_SMT
7658 static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page)
7660 return sprintf(page, "%u\n", sched_smt_power_savings);
7662 static ssize_t sched_smt_power_savings_store(struct sys_device *dev,
7663 const char *buf, size_t count)
7665 return sched_power_savings_store(buf, count, 1);
7667 static SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
7668 sched_smt_power_savings_store);
7671 int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
7675 #ifdef CONFIG_SCHED_SMT
7677 err = sysfs_create_file(&cls->kset.kobj,
7678 &attr_sched_smt_power_savings.attr);
7680 #ifdef CONFIG_SCHED_MC
7681 if (!err && mc_capable())
7682 err = sysfs_create_file(&cls->kset.kobj,
7683 &attr_sched_mc_power_savings.attr);
7687 #endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
7690 * Force a reinitialization of the sched domains hierarchy. The domains
7691 * and groups cannot be updated in place without racing with the balancing
7692 * code, so we temporarily attach all running cpus to the NULL domain
7693 * which will prevent rebalancing while the sched domains are recalculated.
7695 static int update_sched_domains(struct notifier_block *nfb,
7696 unsigned long action, void *hcpu)
7698 int cpu = (int)(long)hcpu;
7701 case CPU_DOWN_PREPARE:
7702 case CPU_DOWN_PREPARE_FROZEN:
7703 disable_runtime(cpu_rq(cpu));
7705 case CPU_UP_PREPARE:
7706 case CPU_UP_PREPARE_FROZEN:
7707 detach_destroy_domains(&cpu_online_map);
7708 free_sched_domains();
7712 case CPU_DOWN_FAILED:
7713 case CPU_DOWN_FAILED_FROZEN:
7715 case CPU_ONLINE_FROZEN:
7716 enable_runtime(cpu_rq(cpu));
7718 case CPU_UP_CANCELED:
7719 case CPU_UP_CANCELED_FROZEN:
7721 case CPU_DEAD_FROZEN:
7723 * Fall through and re-initialise the domains.
7730 #ifndef CONFIG_CPUSETS
7732 * Create default domain partitioning if cpusets are disabled.
7733 * Otherwise we let cpusets rebuild the domains based on the
7737 /* The hotplug lock is already held by cpu_up/cpu_down */
7738 arch_init_sched_domains(&cpu_online_map);
7744 void __init sched_init_smp(void)
7746 cpumask_t non_isolated_cpus;
7748 #if defined(CONFIG_NUMA)
7749 sched_group_nodes_bycpu = kzalloc(nr_cpu_ids * sizeof(void **),
7751 BUG_ON(sched_group_nodes_bycpu == NULL);
7754 mutex_lock(&sched_domains_mutex);
7755 arch_init_sched_domains(&cpu_online_map);
7756 cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
7757 if (cpus_empty(non_isolated_cpus))
7758 cpu_set(smp_processor_id(), non_isolated_cpus);
7759 mutex_unlock(&sched_domains_mutex);
7761 /* XXX: Theoretical race here - CPU may be hotplugged now */
7762 hotcpu_notifier(update_sched_domains, 0);
7765 /* Move init over to a non-isolated CPU */
7766 if (set_cpus_allowed_ptr(current, &non_isolated_cpus) < 0)
7768 sched_init_granularity();
7771 void __init sched_init_smp(void)
7773 sched_init_granularity();
7775 #endif /* CONFIG_SMP */
7777 int in_sched_functions(unsigned long addr)
7779 return in_lock_functions(addr) ||
7780 (addr >= (unsigned long)__sched_text_start
7781 && addr < (unsigned long)__sched_text_end);
7784 static void init_cfs_rq(struct cfs_rq *cfs_rq, struct rq *rq)
7786 cfs_rq->tasks_timeline = RB_ROOT;
7787 INIT_LIST_HEAD(&cfs_rq->tasks);
7788 #ifdef CONFIG_FAIR_GROUP_SCHED
7791 cfs_rq->min_vruntime = (u64)(-(1LL << 20));
7794 static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
7796 struct rt_prio_array *array;
7799 array = &rt_rq->active;
7800 for (i = 0; i < MAX_RT_PRIO; i++) {
7801 INIT_LIST_HEAD(array->queue + i);
7802 __clear_bit(i, array->bitmap);
7804 /* delimiter for bitsearch: */
7805 __set_bit(MAX_RT_PRIO, array->bitmap);
7807 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
7808 rt_rq->highest_prio = MAX_RT_PRIO;
7811 rt_rq->rt_nr_migratory = 0;
7812 rt_rq->overloaded = 0;
7816 rt_rq->rt_throttled = 0;
7817 rt_rq->rt_runtime = 0;
7818 spin_lock_init(&rt_rq->rt_runtime_lock);
7820 #ifdef CONFIG_RT_GROUP_SCHED
7821 rt_rq->rt_nr_boosted = 0;
7826 #ifdef CONFIG_FAIR_GROUP_SCHED
7827 static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
7828 struct sched_entity *se, int cpu, int add,
7829 struct sched_entity *parent)
7831 struct rq *rq = cpu_rq(cpu);
7832 tg->cfs_rq[cpu] = cfs_rq;
7833 init_cfs_rq(cfs_rq, rq);
7836 list_add(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
7839 /* se could be NULL for init_task_group */
7844 se->cfs_rq = &rq->cfs;
7846 se->cfs_rq = parent->my_q;
7849 se->load.weight = tg->shares;
7850 se->load.inv_weight = 0;
7851 se->parent = parent;
7855 #ifdef CONFIG_RT_GROUP_SCHED
7856 static void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
7857 struct sched_rt_entity *rt_se, int cpu, int add,
7858 struct sched_rt_entity *parent)
7860 struct rq *rq = cpu_rq(cpu);
7862 tg->rt_rq[cpu] = rt_rq;
7863 init_rt_rq(rt_rq, rq);
7865 rt_rq->rt_se = rt_se;
7866 rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
7868 list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
7870 tg->rt_se[cpu] = rt_se;
7875 rt_se->rt_rq = &rq->rt;
7877 rt_se->rt_rq = parent->my_q;
7879 rt_se->my_q = rt_rq;
7880 rt_se->parent = parent;
7881 INIT_LIST_HEAD(&rt_se->run_list);
7885 void __init sched_init(void)
7888 unsigned long alloc_size = 0, ptr;
7890 #ifdef CONFIG_FAIR_GROUP_SCHED
7891 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7893 #ifdef CONFIG_RT_GROUP_SCHED
7894 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7896 #ifdef CONFIG_USER_SCHED
7900 * As sched_init() is called before page_alloc is setup,
7901 * we use alloc_bootmem().
7904 ptr = (unsigned long)alloc_bootmem(alloc_size);
7906 #ifdef CONFIG_FAIR_GROUP_SCHED
7907 init_task_group.se = (struct sched_entity **)ptr;
7908 ptr += nr_cpu_ids * sizeof(void **);
7910 init_task_group.cfs_rq = (struct cfs_rq **)ptr;
7911 ptr += nr_cpu_ids * sizeof(void **);
7913 #ifdef CONFIG_USER_SCHED
7914 root_task_group.se = (struct sched_entity **)ptr;
7915 ptr += nr_cpu_ids * sizeof(void **);
7917 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
7918 ptr += nr_cpu_ids * sizeof(void **);
7919 #endif /* CONFIG_USER_SCHED */
7920 #endif /* CONFIG_FAIR_GROUP_SCHED */
7921 #ifdef CONFIG_RT_GROUP_SCHED
7922 init_task_group.rt_se = (struct sched_rt_entity **)ptr;
7923 ptr += nr_cpu_ids * sizeof(void **);
7925 init_task_group.rt_rq = (struct rt_rq **)ptr;
7926 ptr += nr_cpu_ids * sizeof(void **);
7928 #ifdef CONFIG_USER_SCHED
7929 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
7930 ptr += nr_cpu_ids * sizeof(void **);
7932 root_task_group.rt_rq = (struct rt_rq **)ptr;
7933 ptr += nr_cpu_ids * sizeof(void **);
7934 #endif /* CONFIG_USER_SCHED */
7935 #endif /* CONFIG_RT_GROUP_SCHED */
7939 init_defrootdomain();
7942 init_rt_bandwidth(&def_rt_bandwidth,
7943 global_rt_period(), global_rt_runtime());
7945 #ifdef CONFIG_RT_GROUP_SCHED
7946 init_rt_bandwidth(&init_task_group.rt_bandwidth,
7947 global_rt_period(), global_rt_runtime());
7948 #ifdef CONFIG_USER_SCHED
7949 init_rt_bandwidth(&root_task_group.rt_bandwidth,
7950 global_rt_period(), RUNTIME_INF);
7951 #endif /* CONFIG_USER_SCHED */
7952 #endif /* CONFIG_RT_GROUP_SCHED */
7954 #ifdef CONFIG_GROUP_SCHED
7955 list_add(&init_task_group.list, &task_groups);
7956 INIT_LIST_HEAD(&init_task_group.children);
7958 #ifdef CONFIG_USER_SCHED
7959 INIT_LIST_HEAD(&root_task_group.children);
7960 init_task_group.parent = &root_task_group;
7961 list_add(&init_task_group.siblings, &root_task_group.children);
7962 #endif /* CONFIG_USER_SCHED */
7963 #endif /* CONFIG_GROUP_SCHED */
7965 for_each_possible_cpu(i) {
7969 spin_lock_init(&rq->lock);
7970 lockdep_set_class(&rq->lock, &rq->rq_lock_key);
7972 init_cfs_rq(&rq->cfs, rq);
7973 init_rt_rq(&rq->rt, rq);
7974 #ifdef CONFIG_FAIR_GROUP_SCHED
7975 init_task_group.shares = init_task_group_load;
7976 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
7977 #ifdef CONFIG_CGROUP_SCHED
7979 * How much cpu bandwidth does init_task_group get?
7981 * In case of task-groups formed thr' the cgroup filesystem, it
7982 * gets 100% of the cpu resources in the system. This overall
7983 * system cpu resource is divided among the tasks of
7984 * init_task_group and its child task-groups in a fair manner,
7985 * based on each entity's (task or task-group's) weight
7986 * (se->load.weight).
7988 * In other words, if init_task_group has 10 tasks of weight
7989 * 1024) and two child groups A0 and A1 (of weight 1024 each),
7990 * then A0's share of the cpu resource is:
7992 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7994 * We achieve this by letting init_task_group's tasks sit
7995 * directly in rq->cfs (i.e init_task_group->se[] = NULL).
7997 init_tg_cfs_entry(&init_task_group, &rq->cfs, NULL, i, 1, NULL);
7998 #elif defined CONFIG_USER_SCHED
7999 root_task_group.shares = NICE_0_LOAD;
8000 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, 0, NULL);
8002 * In case of task-groups formed thr' the user id of tasks,
8003 * init_task_group represents tasks belonging to root user.
8004 * Hence it forms a sibling of all subsequent groups formed.
8005 * In this case, init_task_group gets only a fraction of overall
8006 * system cpu resource, based on the weight assigned to root
8007 * user's cpu share (INIT_TASK_GROUP_LOAD). This is accomplished
8008 * by letting tasks of init_task_group sit in a separate cfs_rq
8009 * (init_cfs_rq) and having one entity represent this group of
8010 * tasks in rq->cfs (i.e init_task_group->se[] != NULL).
8012 init_tg_cfs_entry(&init_task_group,
8013 &per_cpu(init_cfs_rq, i),
8014 &per_cpu(init_sched_entity, i), i, 1,
8015 root_task_group.se[i]);
8018 #endif /* CONFIG_FAIR_GROUP_SCHED */
8020 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
8021 #ifdef CONFIG_RT_GROUP_SCHED
8022 INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
8023 #ifdef CONFIG_CGROUP_SCHED
8024 init_tg_rt_entry(&init_task_group, &rq->rt, NULL, i, 1, NULL);
8025 #elif defined CONFIG_USER_SCHED
8026 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, 0, NULL);
8027 init_tg_rt_entry(&init_task_group,
8028 &per_cpu(init_rt_rq, i),
8029 &per_cpu(init_sched_rt_entity, i), i, 1,
8030 root_task_group.rt_se[i]);
8034 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
8035 rq->cpu_load[j] = 0;
8039 rq->active_balance = 0;
8040 rq->next_balance = jiffies;
8044 rq->migration_thread = NULL;
8045 INIT_LIST_HEAD(&rq->migration_queue);
8046 rq_attach_root(rq, &def_root_domain);
8049 atomic_set(&rq->nr_iowait, 0);
8052 set_load_weight(&init_task);
8054 #ifdef CONFIG_PREEMPT_NOTIFIERS
8055 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
8059 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL);
8062 #ifdef CONFIG_RT_MUTEXES
8063 plist_head_init(&init_task.pi_waiters, &init_task.pi_lock);
8067 * The boot idle thread does lazy MMU switching as well:
8069 atomic_inc(&init_mm.mm_count);
8070 enter_lazy_tlb(&init_mm, current);
8073 * Make us the idle thread. Technically, schedule() should not be
8074 * called from this thread, however somewhere below it might be,
8075 * but because we are the idle thread, we just pick up running again
8076 * when this runqueue becomes "idle".
8078 init_idle(current, smp_processor_id());
8080 * During early bootup we pretend to be a normal task:
8082 current->sched_class = &fair_sched_class;
8084 scheduler_running = 1;
8087 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
8088 void __might_sleep(char *file, int line)
8091 static unsigned long prev_jiffy; /* ratelimiting */
8093 if ((in_atomic() || irqs_disabled()) &&
8094 system_state == SYSTEM_RUNNING && !oops_in_progress) {
8095 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
8097 prev_jiffy = jiffies;
8098 printk(KERN_ERR "BUG: sleeping function called from invalid"
8099 " context at %s:%d\n", file, line);
8100 printk("in_atomic():%d, irqs_disabled():%d\n",
8101 in_atomic(), irqs_disabled());
8102 debug_show_held_locks(current);
8103 if (irqs_disabled())
8104 print_irqtrace_events(current);
8109 EXPORT_SYMBOL(__might_sleep);
8112 #ifdef CONFIG_MAGIC_SYSRQ
8113 static void normalize_task(struct rq *rq, struct task_struct *p)
8117 update_rq_clock(rq);
8118 on_rq = p->se.on_rq;
8120 deactivate_task(rq, p, 0);
8121 __setscheduler(rq, p, SCHED_NORMAL, 0);
8123 activate_task(rq, p, 0);
8124 resched_task(rq->curr);
8128 void normalize_rt_tasks(void)
8130 struct task_struct *g, *p;
8131 unsigned long flags;
8134 read_lock_irqsave(&tasklist_lock, flags);
8135 do_each_thread(g, p) {
8137 * Only normalize user tasks:
8142 p->se.exec_start = 0;
8143 #ifdef CONFIG_SCHEDSTATS
8144 p->se.wait_start = 0;
8145 p->se.sleep_start = 0;
8146 p->se.block_start = 0;
8151 * Renice negative nice level userspace
8154 if (TASK_NICE(p) < 0 && p->mm)
8155 set_user_nice(p, 0);
8159 spin_lock(&p->pi_lock);
8160 rq = __task_rq_lock(p);
8162 normalize_task(rq, p);
8164 __task_rq_unlock(rq);
8165 spin_unlock(&p->pi_lock);
8166 } while_each_thread(g, p);
8168 read_unlock_irqrestore(&tasklist_lock, flags);
8171 #endif /* CONFIG_MAGIC_SYSRQ */
8175 * These functions are only useful for the IA64 MCA handling.
8177 * They can only be called when the whole system has been
8178 * stopped - every CPU needs to be quiescent, and no scheduling
8179 * activity can take place. Using them for anything else would
8180 * be a serious bug, and as a result, they aren't even visible
8181 * under any other configuration.
8185 * curr_task - return the current task for a given cpu.
8186 * @cpu: the processor in question.
8188 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
8190 struct task_struct *curr_task(int cpu)
8192 return cpu_curr(cpu);
8196 * set_curr_task - set the current task for a given cpu.
8197 * @cpu: the processor in question.
8198 * @p: the task pointer to set.
8200 * Description: This function must only be used when non-maskable interrupts
8201 * are serviced on a separate stack. It allows the architecture to switch the
8202 * notion of the current task on a cpu in a non-blocking manner. This function
8203 * must be called with all CPU's synchronized, and interrupts disabled, the
8204 * and caller must save the original value of the current task (see
8205 * curr_task() above) and restore that value before reenabling interrupts and
8206 * re-starting the system.
8208 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
8210 void set_curr_task(int cpu, struct task_struct *p)
8217 #ifdef CONFIG_FAIR_GROUP_SCHED
8218 static void free_fair_sched_group(struct task_group *tg)
8222 for_each_possible_cpu(i) {
8224 kfree(tg->cfs_rq[i]);
8234 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
8236 struct cfs_rq *cfs_rq;
8237 struct sched_entity *se, *parent_se;
8241 tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL);
8244 tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL);
8248 tg->shares = NICE_0_LOAD;
8250 for_each_possible_cpu(i) {
8253 cfs_rq = kmalloc_node(sizeof(struct cfs_rq),
8254 GFP_KERNEL|__GFP_ZERO, cpu_to_node(i));
8258 se = kmalloc_node(sizeof(struct sched_entity),
8259 GFP_KERNEL|__GFP_ZERO, cpu_to_node(i));
8263 parent_se = parent ? parent->se[i] : NULL;
8264 init_tg_cfs_entry(tg, cfs_rq, se, i, 0, parent_se);
8273 static inline void register_fair_sched_group(struct task_group *tg, int cpu)
8275 list_add_rcu(&tg->cfs_rq[cpu]->leaf_cfs_rq_list,
8276 &cpu_rq(cpu)->leaf_cfs_rq_list);
8279 static inline void unregister_fair_sched_group(struct task_group *tg, int cpu)
8281 list_del_rcu(&tg->cfs_rq[cpu]->leaf_cfs_rq_list);
8283 #else /* !CONFG_FAIR_GROUP_SCHED */
8284 static inline void free_fair_sched_group(struct task_group *tg)
8289 int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
8294 static inline void register_fair_sched_group(struct task_group *tg, int cpu)
8298 static inline void unregister_fair_sched_group(struct task_group *tg, int cpu)
8301 #endif /* CONFIG_FAIR_GROUP_SCHED */
8303 #ifdef CONFIG_RT_GROUP_SCHED
8304 static void free_rt_sched_group(struct task_group *tg)
8308 destroy_rt_bandwidth(&tg->rt_bandwidth);
8310 for_each_possible_cpu(i) {
8312 kfree(tg->rt_rq[i]);
8314 kfree(tg->rt_se[i]);
8322 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
8324 struct rt_rq *rt_rq;
8325 struct sched_rt_entity *rt_se, *parent_se;
8329 tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
8332 tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
8336 init_rt_bandwidth(&tg->rt_bandwidth,
8337 ktime_to_ns(def_rt_bandwidth.rt_period), 0);
8339 for_each_possible_cpu(i) {
8342 rt_rq = kmalloc_node(sizeof(struct rt_rq),
8343 GFP_KERNEL|__GFP_ZERO, cpu_to_node(i));
8347 rt_se = kmalloc_node(sizeof(struct sched_rt_entity),
8348 GFP_KERNEL|__GFP_ZERO, cpu_to_node(i));
8352 parent_se = parent ? parent->rt_se[i] : NULL;
8353 init_tg_rt_entry(tg, rt_rq, rt_se, i, 0, parent_se);
8362 static inline void register_rt_sched_group(struct task_group *tg, int cpu)
8364 list_add_rcu(&tg->rt_rq[cpu]->leaf_rt_rq_list,
8365 &cpu_rq(cpu)->leaf_rt_rq_list);
8368 static inline void unregister_rt_sched_group(struct task_group *tg, int cpu)
8370 list_del_rcu(&tg->rt_rq[cpu]->leaf_rt_rq_list);
8372 #else /* !CONFIG_RT_GROUP_SCHED */
8373 static inline void free_rt_sched_group(struct task_group *tg)
8378 int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
8383 static inline void register_rt_sched_group(struct task_group *tg, int cpu)
8387 static inline void unregister_rt_sched_group(struct task_group *tg, int cpu)
8390 #endif /* CONFIG_RT_GROUP_SCHED */
8392 #ifdef CONFIG_GROUP_SCHED
8393 static void free_sched_group(struct task_group *tg)
8395 free_fair_sched_group(tg);
8396 free_rt_sched_group(tg);
8400 /* allocate runqueue etc for a new task group */
8401 struct task_group *sched_create_group(struct task_group *parent)
8403 struct task_group *tg;
8404 unsigned long flags;
8407 tg = kzalloc(sizeof(*tg), GFP_KERNEL);
8409 return ERR_PTR(-ENOMEM);
8411 if (!alloc_fair_sched_group(tg, parent))
8414 if (!alloc_rt_sched_group(tg, parent))
8417 spin_lock_irqsave(&task_group_lock, flags);
8418 for_each_possible_cpu(i) {
8419 register_fair_sched_group(tg, i);
8420 register_rt_sched_group(tg, i);
8422 list_add_rcu(&tg->list, &task_groups);
8424 WARN_ON(!parent); /* root should already exist */
8426 tg->parent = parent;
8427 list_add_rcu(&tg->siblings, &parent->children);
8428 INIT_LIST_HEAD(&tg->children);
8429 spin_unlock_irqrestore(&task_group_lock, flags);
8434 free_sched_group(tg);
8435 return ERR_PTR(-ENOMEM);
8438 /* rcu callback to free various structures associated with a task group */
8439 static void free_sched_group_rcu(struct rcu_head *rhp)
8441 /* now it should be safe to free those cfs_rqs */
8442 free_sched_group(container_of(rhp, struct task_group, rcu));
8445 /* Destroy runqueue etc associated with a task group */
8446 void sched_destroy_group(struct task_group *tg)
8448 unsigned long flags;
8451 spin_lock_irqsave(&task_group_lock, flags);
8452 for_each_possible_cpu(i) {
8453 unregister_fair_sched_group(tg, i);
8454 unregister_rt_sched_group(tg, i);
8456 list_del_rcu(&tg->list);
8457 list_del_rcu(&tg->siblings);
8458 spin_unlock_irqrestore(&task_group_lock, flags);
8460 /* wait for possible concurrent references to cfs_rqs complete */
8461 call_rcu(&tg->rcu, free_sched_group_rcu);
8464 /* change task's runqueue when it moves between groups.
8465 * The caller of this function should have put the task in its new group
8466 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
8467 * reflect its new group.
8469 void sched_move_task(struct task_struct *tsk)
8472 unsigned long flags;
8475 rq = task_rq_lock(tsk, &flags);
8477 update_rq_clock(rq);
8479 running = task_current(rq, tsk);
8480 on_rq = tsk->se.on_rq;
8483 dequeue_task(rq, tsk, 0);
8484 if (unlikely(running))
8485 tsk->sched_class->put_prev_task(rq, tsk);
8487 set_task_rq(tsk, task_cpu(tsk));
8489 #ifdef CONFIG_FAIR_GROUP_SCHED
8490 if (tsk->sched_class->moved_group)
8491 tsk->sched_class->moved_group(tsk);
8494 if (unlikely(running))
8495 tsk->sched_class->set_curr_task(rq);
8497 enqueue_task(rq, tsk, 0);
8499 task_rq_unlock(rq, &flags);
8501 #endif /* CONFIG_GROUP_SCHED */
8503 #ifdef CONFIG_FAIR_GROUP_SCHED
8504 static void __set_se_shares(struct sched_entity *se, unsigned long shares)
8506 struct cfs_rq *cfs_rq = se->cfs_rq;
8511 dequeue_entity(cfs_rq, se, 0);
8513 se->load.weight = shares;
8514 se->load.inv_weight = 0;
8517 enqueue_entity(cfs_rq, se, 0);
8520 static void set_se_shares(struct sched_entity *se, unsigned long shares)
8522 struct cfs_rq *cfs_rq = se->cfs_rq;
8523 struct rq *rq = cfs_rq->rq;
8524 unsigned long flags;
8526 spin_lock_irqsave(&rq->lock, flags);
8527 __set_se_shares(se, shares);
8528 spin_unlock_irqrestore(&rq->lock, flags);
8531 static DEFINE_MUTEX(shares_mutex);
8533 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
8536 unsigned long flags;
8539 * We can't change the weight of the root cgroup.
8544 if (shares < MIN_SHARES)
8545 shares = MIN_SHARES;
8546 else if (shares > MAX_SHARES)
8547 shares = MAX_SHARES;
8549 mutex_lock(&shares_mutex);
8550 if (tg->shares == shares)
8553 spin_lock_irqsave(&task_group_lock, flags);
8554 for_each_possible_cpu(i)
8555 unregister_fair_sched_group(tg, i);
8556 list_del_rcu(&tg->siblings);
8557 spin_unlock_irqrestore(&task_group_lock, flags);
8559 /* wait for any ongoing reference to this group to finish */
8560 synchronize_sched();
8563 * Now we are free to modify the group's share on each cpu
8564 * w/o tripping rebalance_share or load_balance_fair.
8566 tg->shares = shares;
8567 for_each_possible_cpu(i) {
8571 cfs_rq_set_shares(tg->cfs_rq[i], 0);
8572 set_se_shares(tg->se[i], shares);
8576 * Enable load balance activity on this group, by inserting it back on
8577 * each cpu's rq->leaf_cfs_rq_list.
8579 spin_lock_irqsave(&task_group_lock, flags);
8580 for_each_possible_cpu(i)
8581 register_fair_sched_group(tg, i);
8582 list_add_rcu(&tg->siblings, &tg->parent->children);
8583 spin_unlock_irqrestore(&task_group_lock, flags);
8585 mutex_unlock(&shares_mutex);
8589 unsigned long sched_group_shares(struct task_group *tg)
8595 #ifdef CONFIG_RT_GROUP_SCHED
8597 * Ensure that the real time constraints are schedulable.
8599 static DEFINE_MUTEX(rt_constraints_mutex);
8601 static unsigned long to_ratio(u64 period, u64 runtime)
8603 if (runtime == RUNTIME_INF)
8606 return div64_u64(runtime << 16, period);
8609 #ifdef CONFIG_CGROUP_SCHED
8610 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
8612 struct task_group *tgi, *parent = tg->parent;
8613 unsigned long total = 0;
8616 if (global_rt_period() < period)
8619 return to_ratio(period, runtime) <
8620 to_ratio(global_rt_period(), global_rt_runtime());
8623 if (ktime_to_ns(parent->rt_bandwidth.rt_period) < period)
8627 list_for_each_entry_rcu(tgi, &parent->children, siblings) {
8631 total += to_ratio(ktime_to_ns(tgi->rt_bandwidth.rt_period),
8632 tgi->rt_bandwidth.rt_runtime);
8636 return total + to_ratio(period, runtime) <=
8637 to_ratio(ktime_to_ns(parent->rt_bandwidth.rt_period),
8638 parent->rt_bandwidth.rt_runtime);
8640 #elif defined CONFIG_USER_SCHED
8641 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
8643 struct task_group *tgi;
8644 unsigned long total = 0;
8645 unsigned long global_ratio =
8646 to_ratio(global_rt_period(), global_rt_runtime());
8649 list_for_each_entry_rcu(tgi, &task_groups, list) {
8653 total += to_ratio(ktime_to_ns(tgi->rt_bandwidth.rt_period),
8654 tgi->rt_bandwidth.rt_runtime);
8658 return total + to_ratio(period, runtime) < global_ratio;
8662 /* Must be called with tasklist_lock held */
8663 static inline int tg_has_rt_tasks(struct task_group *tg)
8665 struct task_struct *g, *p;
8666 do_each_thread(g, p) {
8667 if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg)
8669 } while_each_thread(g, p);
8673 static int tg_set_bandwidth(struct task_group *tg,
8674 u64 rt_period, u64 rt_runtime)
8678 mutex_lock(&rt_constraints_mutex);
8679 read_lock(&tasklist_lock);
8680 if (rt_runtime == 0 && tg_has_rt_tasks(tg)) {
8684 if (!__rt_schedulable(tg, rt_period, rt_runtime)) {
8689 spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
8690 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
8691 tg->rt_bandwidth.rt_runtime = rt_runtime;
8693 for_each_possible_cpu(i) {
8694 struct rt_rq *rt_rq = tg->rt_rq[i];
8696 spin_lock(&rt_rq->rt_runtime_lock);
8697 rt_rq->rt_runtime = rt_runtime;
8698 spin_unlock(&rt_rq->rt_runtime_lock);
8700 spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
8702 read_unlock(&tasklist_lock);
8703 mutex_unlock(&rt_constraints_mutex);
8708 int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
8710 u64 rt_runtime, rt_period;
8712 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
8713 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
8714 if (rt_runtime_us < 0)
8715 rt_runtime = RUNTIME_INF;
8717 return tg_set_bandwidth(tg, rt_period, rt_runtime);
8720 long sched_group_rt_runtime(struct task_group *tg)
8724 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
8727 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
8728 do_div(rt_runtime_us, NSEC_PER_USEC);
8729 return rt_runtime_us;
8732 int sched_group_set_rt_period(struct task_group *tg, long rt_period_us)
8734 u64 rt_runtime, rt_period;
8736 rt_period = (u64)rt_period_us * NSEC_PER_USEC;
8737 rt_runtime = tg->rt_bandwidth.rt_runtime;
8739 return tg_set_bandwidth(tg, rt_period, rt_runtime);
8742 long sched_group_rt_period(struct task_group *tg)
8746 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
8747 do_div(rt_period_us, NSEC_PER_USEC);
8748 return rt_period_us;
8751 static int sched_rt_global_constraints(void)
8753 struct task_group *tg = &root_task_group;
8754 u64 rt_runtime, rt_period;
8757 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
8758 rt_runtime = tg->rt_bandwidth.rt_runtime;
8760 mutex_lock(&rt_constraints_mutex);
8761 if (!__rt_schedulable(tg, rt_period, rt_runtime))
8763 mutex_unlock(&rt_constraints_mutex);
8767 #else /* !CONFIG_RT_GROUP_SCHED */
8768 static int sched_rt_global_constraints(void)
8770 unsigned long flags;
8773 spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
8774 for_each_possible_cpu(i) {
8775 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
8777 spin_lock(&rt_rq->rt_runtime_lock);
8778 rt_rq->rt_runtime = global_rt_runtime();
8779 spin_unlock(&rt_rq->rt_runtime_lock);
8781 spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
8785 #endif /* CONFIG_RT_GROUP_SCHED */
8787 int sched_rt_handler(struct ctl_table *table, int write,
8788 struct file *filp, void __user *buffer, size_t *lenp,
8792 int old_period, old_runtime;
8793 static DEFINE_MUTEX(mutex);
8796 old_period = sysctl_sched_rt_period;
8797 old_runtime = sysctl_sched_rt_runtime;
8799 ret = proc_dointvec(table, write, filp, buffer, lenp, ppos);
8801 if (!ret && write) {
8802 ret = sched_rt_global_constraints();
8804 sysctl_sched_rt_period = old_period;
8805 sysctl_sched_rt_runtime = old_runtime;
8807 def_rt_bandwidth.rt_runtime = global_rt_runtime();
8808 def_rt_bandwidth.rt_period =
8809 ns_to_ktime(global_rt_period());
8812 mutex_unlock(&mutex);
8817 #ifdef CONFIG_CGROUP_SCHED
8819 /* return corresponding task_group object of a cgroup */
8820 static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
8822 return container_of(cgroup_subsys_state(cgrp, cpu_cgroup_subsys_id),
8823 struct task_group, css);
8826 static struct cgroup_subsys_state *
8827 cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
8829 struct task_group *tg, *parent;
8831 if (!cgrp->parent) {
8832 /* This is early initialization for the top cgroup */
8833 init_task_group.css.cgroup = cgrp;
8834 return &init_task_group.css;
8837 parent = cgroup_tg(cgrp->parent);
8838 tg = sched_create_group(parent);
8840 return ERR_PTR(-ENOMEM);
8842 /* Bind the cgroup to task_group object we just created */
8843 tg->css.cgroup = cgrp;
8849 cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
8851 struct task_group *tg = cgroup_tg(cgrp);
8853 sched_destroy_group(tg);
8857 cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
8858 struct task_struct *tsk)
8860 #ifdef CONFIG_RT_GROUP_SCHED
8861 /* Don't accept realtime tasks when there is no way for them to run */
8862 if (rt_task(tsk) && cgroup_tg(cgrp)->rt_bandwidth.rt_runtime == 0)
8865 /* We don't support RT-tasks being in separate groups */
8866 if (tsk->sched_class != &fair_sched_class)
8874 cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
8875 struct cgroup *old_cont, struct task_struct *tsk)
8877 sched_move_task(tsk);
8880 #ifdef CONFIG_FAIR_GROUP_SCHED
8881 static int cpu_shares_write_u64(struct cgroup *cgrp, struct cftype *cftype,
8884 return sched_group_set_shares(cgroup_tg(cgrp), shareval);
8887 static u64 cpu_shares_read_u64(struct cgroup *cgrp, struct cftype *cft)
8889 struct task_group *tg = cgroup_tg(cgrp);
8891 return (u64) tg->shares;
8893 #endif /* CONFIG_FAIR_GROUP_SCHED */
8895 #ifdef CONFIG_RT_GROUP_SCHED
8896 static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft,
8899 return sched_group_set_rt_runtime(cgroup_tg(cgrp), val);
8902 static s64 cpu_rt_runtime_read(struct cgroup *cgrp, struct cftype *cft)
8904 return sched_group_rt_runtime(cgroup_tg(cgrp));
8907 static int cpu_rt_period_write_uint(struct cgroup *cgrp, struct cftype *cftype,
8910 return sched_group_set_rt_period(cgroup_tg(cgrp), rt_period_us);
8913 static u64 cpu_rt_period_read_uint(struct cgroup *cgrp, struct cftype *cft)
8915 return sched_group_rt_period(cgroup_tg(cgrp));
8917 #endif /* CONFIG_RT_GROUP_SCHED */
8919 static struct cftype cpu_files[] = {
8920 #ifdef CONFIG_FAIR_GROUP_SCHED
8923 .read_u64 = cpu_shares_read_u64,
8924 .write_u64 = cpu_shares_write_u64,
8927 #ifdef CONFIG_RT_GROUP_SCHED
8929 .name = "rt_runtime_us",
8930 .read_s64 = cpu_rt_runtime_read,
8931 .write_s64 = cpu_rt_runtime_write,
8934 .name = "rt_period_us",
8935 .read_u64 = cpu_rt_period_read_uint,
8936 .write_u64 = cpu_rt_period_write_uint,
8941 static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
8943 return cgroup_add_files(cont, ss, cpu_files, ARRAY_SIZE(cpu_files));
8946 struct cgroup_subsys cpu_cgroup_subsys = {
8948 .create = cpu_cgroup_create,
8949 .destroy = cpu_cgroup_destroy,
8950 .can_attach = cpu_cgroup_can_attach,
8951 .attach = cpu_cgroup_attach,
8952 .populate = cpu_cgroup_populate,
8953 .subsys_id = cpu_cgroup_subsys_id,
8957 #endif /* CONFIG_CGROUP_SCHED */
8959 #ifdef CONFIG_CGROUP_CPUACCT
8962 * CPU accounting code for task groups.
8964 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
8965 * (balbir@in.ibm.com).
8968 /* track cpu usage of a group of tasks */
8970 struct cgroup_subsys_state css;
8971 /* cpuusage holds pointer to a u64-type object on every cpu */
8975 struct cgroup_subsys cpuacct_subsys;
8977 /* return cpu accounting group corresponding to this container */
8978 static inline struct cpuacct *cgroup_ca(struct cgroup *cgrp)
8980 return container_of(cgroup_subsys_state(cgrp, cpuacct_subsys_id),
8981 struct cpuacct, css);
8984 /* return cpu accounting group to which this task belongs */
8985 static inline struct cpuacct *task_ca(struct task_struct *tsk)
8987 return container_of(task_subsys_state(tsk, cpuacct_subsys_id),
8988 struct cpuacct, css);
8991 /* create a new cpu accounting group */
8992 static struct cgroup_subsys_state *cpuacct_create(
8993 struct cgroup_subsys *ss, struct cgroup *cgrp)
8995 struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
8998 return ERR_PTR(-ENOMEM);
9000 ca->cpuusage = alloc_percpu(u64);
9001 if (!ca->cpuusage) {
9003 return ERR_PTR(-ENOMEM);
9009 /* destroy an existing cpu accounting group */
9011 cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
9013 struct cpuacct *ca = cgroup_ca(cgrp);
9015 free_percpu(ca->cpuusage);
9019 /* return total cpu usage (in nanoseconds) of a group */
9020 static u64 cpuusage_read(struct cgroup *cgrp, struct cftype *cft)
9022 struct cpuacct *ca = cgroup_ca(cgrp);
9023 u64 totalcpuusage = 0;
9026 for_each_possible_cpu(i) {
9027 u64 *cpuusage = percpu_ptr(ca->cpuusage, i);
9030 * Take rq->lock to make 64-bit addition safe on 32-bit
9033 spin_lock_irq(&cpu_rq(i)->lock);
9034 totalcpuusage += *cpuusage;
9035 spin_unlock_irq(&cpu_rq(i)->lock);
9038 return totalcpuusage;
9041 static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype,
9044 struct cpuacct *ca = cgroup_ca(cgrp);
9053 for_each_possible_cpu(i) {
9054 u64 *cpuusage = percpu_ptr(ca->cpuusage, i);
9056 spin_lock_irq(&cpu_rq(i)->lock);
9058 spin_unlock_irq(&cpu_rq(i)->lock);
9064 static struct cftype files[] = {
9067 .read_u64 = cpuusage_read,
9068 .write_u64 = cpuusage_write,
9072 static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
9074 return cgroup_add_files(cgrp, ss, files, ARRAY_SIZE(files));
9078 * charge this task's execution time to its accounting group.
9080 * called with rq->lock held.
9082 static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
9086 if (!cpuacct_subsys.active)
9091 u64 *cpuusage = percpu_ptr(ca->cpuusage, task_cpu(tsk));
9093 *cpuusage += cputime;
9097 struct cgroup_subsys cpuacct_subsys = {
9099 .create = cpuacct_create,
9100 .destroy = cpuacct_destroy,
9101 .populate = cpuacct_populate,
9102 .subsys_id = cpuacct_subsys_id,
9104 #endif /* CONFIG_CGROUP_CPUACCT */