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>
71 #include <asm/irq_regs.h>
74 * Scheduler clock - returns current time in nanosec units.
75 * This is default implementation.
76 * Architectures and sub-architectures can override this.
78 unsigned long long __attribute__((weak)) sched_clock(void)
80 return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ);
84 * Convert user-nice values [ -20 ... 0 ... 19 ]
85 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
88 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
89 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
90 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
93 * 'User priority' is the nice value converted to something we
94 * can work with better when scaling various scheduler parameters,
95 * it's a [ 0 ... 39 ] range.
97 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
98 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
99 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
102 * Helpers for converting nanosecond timing to jiffy resolution
104 #define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
106 #define NICE_0_LOAD SCHED_LOAD_SCALE
107 #define NICE_0_SHIFT SCHED_LOAD_SHIFT
110 * These are the 'tuning knobs' of the scheduler:
112 * default timeslice is 100 msecs (used only for SCHED_RR tasks).
113 * Timeslices get refilled after they expire.
115 #define DEF_TIMESLICE (100 * HZ / 1000)
119 * Divide a load by a sched group cpu_power : (load / sg->__cpu_power)
120 * Since cpu_power is a 'constant', we can use a reciprocal divide.
122 static inline u32 sg_div_cpu_power(const struct sched_group *sg, u32 load)
124 return reciprocal_divide(load, sg->reciprocal_cpu_power);
128 * Each time a sched group cpu_power is changed,
129 * we must compute its reciprocal value
131 static inline void sg_inc_cpu_power(struct sched_group *sg, u32 val)
133 sg->__cpu_power += val;
134 sg->reciprocal_cpu_power = reciprocal_value(sg->__cpu_power);
138 static inline int rt_policy(int policy)
140 if (unlikely(policy == SCHED_FIFO) || unlikely(policy == SCHED_RR))
145 static inline int task_has_rt_policy(struct task_struct *p)
147 return rt_policy(p->policy);
151 * This is the priority-queue data structure of the RT scheduling class:
153 struct rt_prio_array {
154 DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
155 struct list_head queue[MAX_RT_PRIO];
158 #ifdef CONFIG_FAIR_GROUP_SCHED
160 #include <linux/cgroup.h>
164 static LIST_HEAD(task_groups);
166 /* task group related information */
168 #ifdef CONFIG_FAIR_CGROUP_SCHED
169 struct cgroup_subsys_state css;
171 /* schedulable entities of this group on each cpu */
172 struct sched_entity **se;
173 /* runqueue "owned" by this group on each cpu */
174 struct cfs_rq **cfs_rq;
176 struct sched_rt_entity **rt_se;
177 struct rt_rq **rt_rq;
179 unsigned int rt_ratio;
182 * shares assigned to a task group governs how much of cpu bandwidth
183 * is allocated to the group. The more shares a group has, the more is
184 * the cpu bandwidth allocated to it.
186 * For ex, lets say that there are three task groups, A, B and C which
187 * have been assigned shares 1000, 2000 and 3000 respectively. Then,
188 * cpu bandwidth allocated by the scheduler to task groups A, B and C
191 * Bw(A) = 1000/(1000+2000+3000) * 100 = 16.66%
192 * Bw(B) = 2000/(1000+2000+3000) * 100 = 33.33%
193 * Bw(C) = 3000/(1000+2000+3000) * 100 = 50%
195 * The weight assigned to a task group's schedulable entities on every
196 * cpu (task_group.se[a_cpu]->load.weight) is derived from the task
197 * group's shares. For ex: lets say that task group A has been
198 * assigned shares of 1000 and there are two CPUs in a system. Then,
200 * tg_A->se[0]->load.weight = tg_A->se[1]->load.weight = 1000;
202 * Note: It's not necessary that each of a task's group schedulable
203 * entity have the same weight on all CPUs. If the group
204 * has 2 of its tasks on CPU0 and 1 task on CPU1, then a
205 * better distribution of weight could be:
207 * tg_A->se[0]->load.weight = 2/3 * 2000 = 1333
208 * tg_A->se[1]->load.weight = 1/2 * 2000 = 667
210 * rebalance_shares() is responsible for distributing the shares of a
211 * task groups like this among the group's schedulable entities across
215 unsigned long shares;
218 struct list_head list;
221 /* Default task group's sched entity on each cpu */
222 static DEFINE_PER_CPU(struct sched_entity, init_sched_entity);
223 /* Default task group's cfs_rq on each cpu */
224 static DEFINE_PER_CPU(struct cfs_rq, init_cfs_rq) ____cacheline_aligned_in_smp;
226 static DEFINE_PER_CPU(struct sched_rt_entity, init_sched_rt_entity);
227 static DEFINE_PER_CPU(struct rt_rq, init_rt_rq) ____cacheline_aligned_in_smp;
229 static struct sched_entity *init_sched_entity_p[NR_CPUS];
230 static struct cfs_rq *init_cfs_rq_p[NR_CPUS];
232 static struct sched_rt_entity *init_sched_rt_entity_p[NR_CPUS];
233 static struct rt_rq *init_rt_rq_p[NR_CPUS];
235 /* task_group_mutex serializes add/remove of task groups and also changes to
236 * a task group's cpu shares.
238 static DEFINE_MUTEX(task_group_mutex);
240 /* doms_cur_mutex serializes access to doms_cur[] array */
241 static DEFINE_MUTEX(doms_cur_mutex);
244 /* kernel thread that runs rebalance_shares() periodically */
245 static struct task_struct *lb_monitor_task;
246 static int load_balance_monitor(void *unused);
249 static void set_se_shares(struct sched_entity *se, unsigned long shares);
251 /* Default task group.
252 * Every task in system belong to this group at bootup.
254 struct task_group init_task_group = {
255 .se = init_sched_entity_p,
256 .cfs_rq = init_cfs_rq_p,
258 .rt_se = init_sched_rt_entity_p,
259 .rt_rq = init_rt_rq_p,
262 #ifdef CONFIG_FAIR_USER_SCHED
263 # define INIT_TASK_GROUP_LOAD (2*NICE_0_LOAD)
265 # define INIT_TASK_GROUP_LOAD NICE_0_LOAD
268 #define MIN_GROUP_SHARES 2
270 static int init_task_group_load = INIT_TASK_GROUP_LOAD;
272 /* return group to which a task belongs */
273 static inline struct task_group *task_group(struct task_struct *p)
275 struct task_group *tg;
277 #ifdef CONFIG_FAIR_USER_SCHED
279 #elif defined(CONFIG_FAIR_CGROUP_SCHED)
280 tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
281 struct task_group, css);
283 tg = &init_task_group;
288 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
289 static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
291 p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
292 p->se.parent = task_group(p)->se[cpu];
294 p->rt.rt_rq = task_group(p)->rt_rq[cpu];
295 p->rt.parent = task_group(p)->rt_se[cpu];
298 static inline void lock_task_group_list(void)
300 mutex_lock(&task_group_mutex);
303 static inline void unlock_task_group_list(void)
305 mutex_unlock(&task_group_mutex);
308 static inline void lock_doms_cur(void)
310 mutex_lock(&doms_cur_mutex);
313 static inline void unlock_doms_cur(void)
315 mutex_unlock(&doms_cur_mutex);
320 static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
321 static inline void lock_task_group_list(void) { }
322 static inline void unlock_task_group_list(void) { }
323 static inline void lock_doms_cur(void) { }
324 static inline void unlock_doms_cur(void) { }
326 #endif /* CONFIG_FAIR_GROUP_SCHED */
328 /* CFS-related fields in a runqueue */
330 struct load_weight load;
331 unsigned long nr_running;
336 struct rb_root tasks_timeline;
337 struct rb_node *rb_leftmost;
338 struct rb_node *rb_load_balance_curr;
339 /* 'curr' points to currently running entity on this cfs_rq.
340 * It is set to NULL otherwise (i.e when none are currently running).
342 struct sched_entity *curr;
344 unsigned long nr_spread_over;
346 #ifdef CONFIG_FAIR_GROUP_SCHED
347 struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
350 * leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
351 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
352 * (like users, containers etc.)
354 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
355 * list is used during load balance.
357 struct list_head leaf_cfs_rq_list;
358 struct task_group *tg; /* group that "owns" this runqueue */
362 /* Real-Time classes' related field in a runqueue: */
364 struct rt_prio_array active;
365 unsigned long rt_nr_running;
366 #if defined CONFIG_SMP || defined CONFIG_FAIR_GROUP_SCHED
367 int highest_prio; /* highest queued rt task prio */
370 unsigned long rt_nr_migratory;
376 #ifdef CONFIG_FAIR_GROUP_SCHED
378 struct list_head leaf_rt_rq_list;
379 struct task_group *tg;
380 struct sched_rt_entity *rt_se;
387 * We add the notion of a root-domain which will be used to define per-domain
388 * variables. Each exclusive cpuset essentially defines an island domain by
389 * fully partitioning the member cpus from any other cpuset. Whenever a new
390 * exclusive cpuset is created, we also create and attach a new root-domain
400 * The "RT overload" flag: it gets set if a CPU has more than
401 * one runnable RT task.
408 * By default the system creates a single root-domain with all cpus as
409 * members (mimicking the global state we have today).
411 static struct root_domain def_root_domain;
416 * This is the main, per-CPU runqueue data structure.
418 * Locking rule: those places that want to lock multiple runqueues
419 * (such as the load balancing or the thread migration code), lock
420 * acquire operations must be ordered by ascending &runqueue.
427 * nr_running and cpu_load should be in the same cacheline because
428 * remote CPUs use both these fields when doing load calculation.
430 unsigned long nr_running;
431 #define CPU_LOAD_IDX_MAX 5
432 unsigned long cpu_load[CPU_LOAD_IDX_MAX];
433 unsigned char idle_at_tick;
435 unsigned char in_nohz_recently;
437 /* capture load from *all* tasks on this cpu: */
438 struct load_weight load;
439 unsigned long nr_load_updates;
444 u64 rt_period_expire;
446 #ifdef CONFIG_FAIR_GROUP_SCHED
447 /* list of leaf cfs_rq on this cpu: */
448 struct list_head leaf_cfs_rq_list;
449 struct list_head leaf_rt_rq_list;
453 * This is part of a global counter where only the total sum
454 * over all CPUs matters. A task can increase this counter on
455 * one CPU and if it got migrated afterwards it may decrease
456 * it on another CPU. Always updated under the runqueue lock:
458 unsigned long nr_uninterruptible;
460 struct task_struct *curr, *idle;
461 unsigned long next_balance;
462 struct mm_struct *prev_mm;
464 u64 clock, prev_clock_raw;
467 unsigned int clock_warps, clock_overflows;
469 unsigned int clock_deep_idle_events;
475 struct root_domain *rd;
476 struct sched_domain *sd;
478 /* For active balancing */
481 /* cpu of this runqueue: */
484 struct task_struct *migration_thread;
485 struct list_head migration_queue;
488 #ifdef CONFIG_SCHED_HRTICK
489 unsigned long hrtick_flags;
490 ktime_t hrtick_expire;
491 struct hrtimer hrtick_timer;
494 #ifdef CONFIG_SCHEDSTATS
496 struct sched_info rq_sched_info;
498 /* sys_sched_yield() stats */
499 unsigned int yld_exp_empty;
500 unsigned int yld_act_empty;
501 unsigned int yld_both_empty;
502 unsigned int yld_count;
504 /* schedule() stats */
505 unsigned int sched_switch;
506 unsigned int sched_count;
507 unsigned int sched_goidle;
509 /* try_to_wake_up() stats */
510 unsigned int ttwu_count;
511 unsigned int ttwu_local;
514 unsigned int bkl_count;
516 struct lock_class_key rq_lock_key;
519 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
521 static inline void check_preempt_curr(struct rq *rq, struct task_struct *p)
523 rq->curr->sched_class->check_preempt_curr(rq, p);
526 static inline int cpu_of(struct rq *rq)
536 * Update the per-runqueue clock, as finegrained as the platform can give
537 * us, but without assuming monotonicity, etc.:
539 static void __update_rq_clock(struct rq *rq)
541 u64 prev_raw = rq->prev_clock_raw;
542 u64 now = sched_clock();
543 s64 delta = now - prev_raw;
544 u64 clock = rq->clock;
546 #ifdef CONFIG_SCHED_DEBUG
547 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
550 * Protect against sched_clock() occasionally going backwards:
552 if (unlikely(delta < 0)) {
557 * Catch too large forward jumps too:
559 if (unlikely(clock + delta > rq->tick_timestamp + TICK_NSEC)) {
560 if (clock < rq->tick_timestamp + TICK_NSEC)
561 clock = rq->tick_timestamp + TICK_NSEC;
564 rq->clock_overflows++;
566 if (unlikely(delta > rq->clock_max_delta))
567 rq->clock_max_delta = delta;
572 rq->prev_clock_raw = now;
576 static void update_rq_clock(struct rq *rq)
578 if (likely(smp_processor_id() == cpu_of(rq)))
579 __update_rq_clock(rq);
583 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
584 * See detach_destroy_domains: synchronize_sched for details.
586 * The domain tree of any CPU may only be accessed from within
587 * preempt-disabled sections.
589 #define for_each_domain(cpu, __sd) \
590 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
592 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
593 #define this_rq() (&__get_cpu_var(runqueues))
594 #define task_rq(p) cpu_rq(task_cpu(p))
595 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
598 * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
600 #ifdef CONFIG_SCHED_DEBUG
601 # define const_debug __read_mostly
603 # define const_debug static const
607 * Debugging: various feature bits
610 SCHED_FEAT_NEW_FAIR_SLEEPERS = 1,
611 SCHED_FEAT_WAKEUP_PREEMPT = 2,
612 SCHED_FEAT_START_DEBIT = 4,
613 SCHED_FEAT_TREE_AVG = 8,
614 SCHED_FEAT_APPROX_AVG = 16,
615 SCHED_FEAT_HRTICK = 32,
616 SCHED_FEAT_DOUBLE_TICK = 64,
619 const_debug unsigned int sysctl_sched_features =
620 SCHED_FEAT_NEW_FAIR_SLEEPERS * 1 |
621 SCHED_FEAT_WAKEUP_PREEMPT * 1 |
622 SCHED_FEAT_START_DEBIT * 1 |
623 SCHED_FEAT_TREE_AVG * 0 |
624 SCHED_FEAT_APPROX_AVG * 0 |
625 SCHED_FEAT_HRTICK * 1 |
626 SCHED_FEAT_DOUBLE_TICK * 0;
628 #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x)
631 * Number of tasks to iterate in a single balance run.
632 * Limited because this is done with IRQs disabled.
634 const_debug unsigned int sysctl_sched_nr_migrate = 32;
637 * period over which we measure -rt task cpu usage in ms.
640 const_debug unsigned int sysctl_sched_rt_period = 1000;
642 #define SCHED_RT_FRAC_SHIFT 16
643 #define SCHED_RT_FRAC (1UL << SCHED_RT_FRAC_SHIFT)
646 * ratio of time -rt tasks may consume.
649 const_debug unsigned int sysctl_sched_rt_ratio = 62259;
652 * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
653 * clock constructed from sched_clock():
655 unsigned long long cpu_clock(int cpu)
657 unsigned long long now;
661 local_irq_save(flags);
664 * Only call sched_clock() if the scheduler has already been
665 * initialized (some code might call cpu_clock() very early):
670 local_irq_restore(flags);
674 EXPORT_SYMBOL_GPL(cpu_clock);
676 #ifndef prepare_arch_switch
677 # define prepare_arch_switch(next) do { } while (0)
679 #ifndef finish_arch_switch
680 # define finish_arch_switch(prev) do { } while (0)
683 static inline int task_current(struct rq *rq, struct task_struct *p)
685 return rq->curr == p;
688 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
689 static inline int task_running(struct rq *rq, struct task_struct *p)
691 return task_current(rq, p);
694 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
698 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
700 #ifdef CONFIG_DEBUG_SPINLOCK
701 /* this is a valid case when another task releases the spinlock */
702 rq->lock.owner = current;
705 * If we are tracking spinlock dependencies then we have to
706 * fix up the runqueue lock - which gets 'carried over' from
709 spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
711 spin_unlock_irq(&rq->lock);
714 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
715 static inline int task_running(struct rq *rq, struct task_struct *p)
720 return task_current(rq, p);
724 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
728 * We can optimise this out completely for !SMP, because the
729 * SMP rebalancing from interrupt is the only thing that cares
734 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
735 spin_unlock_irq(&rq->lock);
737 spin_unlock(&rq->lock);
741 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
745 * After ->oncpu is cleared, the task can be moved to a different CPU.
746 * We must ensure this doesn't happen until the switch is completely
752 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
756 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
759 * __task_rq_lock - lock the runqueue a given task resides on.
760 * Must be called interrupts disabled.
762 static inline struct rq *__task_rq_lock(struct task_struct *p)
766 struct rq *rq = task_rq(p);
767 spin_lock(&rq->lock);
768 if (likely(rq == task_rq(p)))
770 spin_unlock(&rq->lock);
775 * task_rq_lock - lock the runqueue a given task resides on and disable
776 * interrupts. Note the ordering: we can safely lookup the task_rq without
777 * explicitly disabling preemption.
779 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
785 local_irq_save(*flags);
787 spin_lock(&rq->lock);
788 if (likely(rq == task_rq(p)))
790 spin_unlock_irqrestore(&rq->lock, *flags);
794 static void __task_rq_unlock(struct rq *rq)
797 spin_unlock(&rq->lock);
800 static inline void task_rq_unlock(struct rq *rq, unsigned long *flags)
803 spin_unlock_irqrestore(&rq->lock, *flags);
807 * this_rq_lock - lock this runqueue and disable interrupts.
809 static struct rq *this_rq_lock(void)
816 spin_lock(&rq->lock);
822 * We are going deep-idle (irqs are disabled):
824 void sched_clock_idle_sleep_event(void)
826 struct rq *rq = cpu_rq(smp_processor_id());
828 spin_lock(&rq->lock);
829 __update_rq_clock(rq);
830 spin_unlock(&rq->lock);
831 rq->clock_deep_idle_events++;
833 EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
836 * We just idled delta nanoseconds (called with irqs disabled):
838 void sched_clock_idle_wakeup_event(u64 delta_ns)
840 struct rq *rq = cpu_rq(smp_processor_id());
841 u64 now = sched_clock();
843 touch_softlockup_watchdog();
844 rq->idle_clock += delta_ns;
846 * Override the previous timestamp and ignore all
847 * sched_clock() deltas that occured while we idled,
848 * and use the PM-provided delta_ns to advance the
851 spin_lock(&rq->lock);
852 rq->prev_clock_raw = now;
853 rq->clock += delta_ns;
854 spin_unlock(&rq->lock);
856 EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
858 static void __resched_task(struct task_struct *p, int tif_bit);
860 static inline void resched_task(struct task_struct *p)
862 __resched_task(p, TIF_NEED_RESCHED);
865 #ifdef CONFIG_SCHED_HRTICK
867 * Use HR-timers to deliver accurate preemption points.
869 * Its all a bit involved since we cannot program an hrt while holding the
870 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
873 * When we get rescheduled we reprogram the hrtick_timer outside of the
876 static inline void resched_hrt(struct task_struct *p)
878 __resched_task(p, TIF_HRTICK_RESCHED);
881 static inline void resched_rq(struct rq *rq)
885 spin_lock_irqsave(&rq->lock, flags);
886 resched_task(rq->curr);
887 spin_unlock_irqrestore(&rq->lock, flags);
891 HRTICK_SET, /* re-programm hrtick_timer */
892 HRTICK_RESET, /* not a new slice */
897 * - enabled by features
898 * - hrtimer is actually high res
900 static inline int hrtick_enabled(struct rq *rq)
902 if (!sched_feat(HRTICK))
904 return hrtimer_is_hres_active(&rq->hrtick_timer);
908 * Called to set the hrtick timer state.
910 * called with rq->lock held and irqs disabled
912 static void hrtick_start(struct rq *rq, u64 delay, int reset)
914 assert_spin_locked(&rq->lock);
917 * preempt at: now + delay
920 ktime_add_ns(rq->hrtick_timer.base->get_time(), delay);
922 * indicate we need to program the timer
924 __set_bit(HRTICK_SET, &rq->hrtick_flags);
926 __set_bit(HRTICK_RESET, &rq->hrtick_flags);
929 * New slices are called from the schedule path and don't need a
933 resched_hrt(rq->curr);
936 static void hrtick_clear(struct rq *rq)
938 if (hrtimer_active(&rq->hrtick_timer))
939 hrtimer_cancel(&rq->hrtick_timer);
943 * Update the timer from the possible pending state.
945 static void hrtick_set(struct rq *rq)
951 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
953 spin_lock_irqsave(&rq->lock, flags);
954 set = __test_and_clear_bit(HRTICK_SET, &rq->hrtick_flags);
955 reset = __test_and_clear_bit(HRTICK_RESET, &rq->hrtick_flags);
956 time = rq->hrtick_expire;
957 clear_thread_flag(TIF_HRTICK_RESCHED);
958 spin_unlock_irqrestore(&rq->lock, flags);
961 hrtimer_start(&rq->hrtick_timer, time, HRTIMER_MODE_ABS);
962 if (reset && !hrtimer_active(&rq->hrtick_timer))
969 * High-resolution timer tick.
970 * Runs from hardirq context with interrupts disabled.
972 static enum hrtimer_restart hrtick(struct hrtimer *timer)
974 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
976 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
978 spin_lock(&rq->lock);
979 __update_rq_clock(rq);
980 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
981 spin_unlock(&rq->lock);
983 return HRTIMER_NORESTART;
986 static inline void init_rq_hrtick(struct rq *rq)
988 rq->hrtick_flags = 0;
989 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
990 rq->hrtick_timer.function = hrtick;
991 rq->hrtick_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ;
994 void hrtick_resched(void)
999 if (!test_thread_flag(TIF_HRTICK_RESCHED))
1002 local_irq_save(flags);
1003 rq = cpu_rq(smp_processor_id());
1005 local_irq_restore(flags);
1008 static inline void hrtick_clear(struct rq *rq)
1012 static inline void hrtick_set(struct rq *rq)
1016 static inline void init_rq_hrtick(struct rq *rq)
1020 void hrtick_resched(void)
1026 * resched_task - mark a task 'to be rescheduled now'.
1028 * On UP this means the setting of the need_resched flag, on SMP it
1029 * might also involve a cross-CPU call to trigger the scheduler on
1034 #ifndef tsk_is_polling
1035 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1038 static void __resched_task(struct task_struct *p, int tif_bit)
1042 assert_spin_locked(&task_rq(p)->lock);
1044 if (unlikely(test_tsk_thread_flag(p, tif_bit)))
1047 set_tsk_thread_flag(p, tif_bit);
1050 if (cpu == smp_processor_id())
1053 /* NEED_RESCHED must be visible before we test polling */
1055 if (!tsk_is_polling(p))
1056 smp_send_reschedule(cpu);
1059 static void resched_cpu(int cpu)
1061 struct rq *rq = cpu_rq(cpu);
1062 unsigned long flags;
1064 if (!spin_trylock_irqsave(&rq->lock, flags))
1066 resched_task(cpu_curr(cpu));
1067 spin_unlock_irqrestore(&rq->lock, flags);
1070 static void __resched_task(struct task_struct *p, int tif_bit)
1072 assert_spin_locked(&task_rq(p)->lock);
1073 set_tsk_thread_flag(p, tif_bit);
1077 #if BITS_PER_LONG == 32
1078 # define WMULT_CONST (~0UL)
1080 # define WMULT_CONST (1UL << 32)
1083 #define WMULT_SHIFT 32
1086 * Shift right and round:
1088 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
1090 static unsigned long
1091 calc_delta_mine(unsigned long delta_exec, unsigned long weight,
1092 struct load_weight *lw)
1096 if (unlikely(!lw->inv_weight))
1097 lw->inv_weight = (WMULT_CONST - lw->weight/2) / lw->weight + 1;
1099 tmp = (u64)delta_exec * weight;
1101 * Check whether we'd overflow the 64-bit multiplication:
1103 if (unlikely(tmp > WMULT_CONST))
1104 tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
1107 tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
1109 return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
1112 static inline unsigned long
1113 calc_delta_fair(unsigned long delta_exec, struct load_weight *lw)
1115 return calc_delta_mine(delta_exec, NICE_0_LOAD, lw);
1118 static inline void update_load_add(struct load_weight *lw, unsigned long inc)
1123 static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
1129 * To aid in avoiding the subversion of "niceness" due to uneven distribution
1130 * of tasks with abnormal "nice" values across CPUs the contribution that
1131 * each task makes to its run queue's load is weighted according to its
1132 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
1133 * scaled version of the new time slice allocation that they receive on time
1137 #define WEIGHT_IDLEPRIO 2
1138 #define WMULT_IDLEPRIO (1 << 31)
1141 * Nice levels are multiplicative, with a gentle 10% change for every
1142 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
1143 * nice 1, it will get ~10% less CPU time than another CPU-bound task
1144 * that remained on nice 0.
1146 * The "10% effect" is relative and cumulative: from _any_ nice level,
1147 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
1148 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
1149 * If a task goes up by ~10% and another task goes down by ~10% then
1150 * the relative distance between them is ~25%.)
1152 static const int prio_to_weight[40] = {
1153 /* -20 */ 88761, 71755, 56483, 46273, 36291,
1154 /* -15 */ 29154, 23254, 18705, 14949, 11916,
1155 /* -10 */ 9548, 7620, 6100, 4904, 3906,
1156 /* -5 */ 3121, 2501, 1991, 1586, 1277,
1157 /* 0 */ 1024, 820, 655, 526, 423,
1158 /* 5 */ 335, 272, 215, 172, 137,
1159 /* 10 */ 110, 87, 70, 56, 45,
1160 /* 15 */ 36, 29, 23, 18, 15,
1164 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
1166 * In cases where the weight does not change often, we can use the
1167 * precalculated inverse to speed up arithmetics by turning divisions
1168 * into multiplications:
1170 static const u32 prio_to_wmult[40] = {
1171 /* -20 */ 48388, 59856, 76040, 92818, 118348,
1172 /* -15 */ 147320, 184698, 229616, 287308, 360437,
1173 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
1174 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
1175 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
1176 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
1177 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
1178 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
1181 static void activate_task(struct rq *rq, struct task_struct *p, int wakeup);
1184 * runqueue iterator, to support SMP load-balancing between different
1185 * scheduling classes, without having to expose their internal data
1186 * structures to the load-balancing proper:
1188 struct rq_iterator {
1190 struct task_struct *(*start)(void *);
1191 struct task_struct *(*next)(void *);
1195 static unsigned long
1196 balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
1197 unsigned long max_load_move, struct sched_domain *sd,
1198 enum cpu_idle_type idle, int *all_pinned,
1199 int *this_best_prio, struct rq_iterator *iterator);
1202 iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
1203 struct sched_domain *sd, enum cpu_idle_type idle,
1204 struct rq_iterator *iterator);
1207 #ifdef CONFIG_CGROUP_CPUACCT
1208 static void cpuacct_charge(struct task_struct *tsk, u64 cputime);
1210 static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {}
1213 static inline void inc_cpu_load(struct rq *rq, unsigned long load)
1215 update_load_add(&rq->load, load);
1218 static inline void dec_cpu_load(struct rq *rq, unsigned long load)
1220 update_load_sub(&rq->load, load);
1224 static unsigned long source_load(int cpu, int type);
1225 static unsigned long target_load(int cpu, int type);
1226 static unsigned long cpu_avg_load_per_task(int cpu);
1227 static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
1228 #endif /* CONFIG_SMP */
1230 #include "sched_stats.h"
1231 #include "sched_idletask.c"
1232 #include "sched_fair.c"
1233 #include "sched_rt.c"
1234 #ifdef CONFIG_SCHED_DEBUG
1235 # include "sched_debug.c"
1238 #define sched_class_highest (&rt_sched_class)
1240 static void inc_nr_running(struct task_struct *p, struct rq *rq)
1245 static void dec_nr_running(struct task_struct *p, struct rq *rq)
1250 static void set_load_weight(struct task_struct *p)
1252 if (task_has_rt_policy(p)) {
1253 p->se.load.weight = prio_to_weight[0] * 2;
1254 p->se.load.inv_weight = prio_to_wmult[0] >> 1;
1259 * SCHED_IDLE tasks get minimal weight:
1261 if (p->policy == SCHED_IDLE) {
1262 p->se.load.weight = WEIGHT_IDLEPRIO;
1263 p->se.load.inv_weight = WMULT_IDLEPRIO;
1267 p->se.load.weight = prio_to_weight[p->static_prio - MAX_RT_PRIO];
1268 p->se.load.inv_weight = prio_to_wmult[p->static_prio - MAX_RT_PRIO];
1271 static void enqueue_task(struct rq *rq, struct task_struct *p, int wakeup)
1273 sched_info_queued(p);
1274 p->sched_class->enqueue_task(rq, p, wakeup);
1278 static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep)
1280 p->sched_class->dequeue_task(rq, p, sleep);
1285 * __normal_prio - return the priority that is based on the static prio
1287 static inline int __normal_prio(struct task_struct *p)
1289 return p->static_prio;
1293 * Calculate the expected normal priority: i.e. priority
1294 * without taking RT-inheritance into account. Might be
1295 * boosted by interactivity modifiers. Changes upon fork,
1296 * setprio syscalls, and whenever the interactivity
1297 * estimator recalculates.
1299 static inline int normal_prio(struct task_struct *p)
1303 if (task_has_rt_policy(p))
1304 prio = MAX_RT_PRIO-1 - p->rt_priority;
1306 prio = __normal_prio(p);
1311 * Calculate the current priority, i.e. the priority
1312 * taken into account by the scheduler. This value might
1313 * be boosted by RT tasks, or might be boosted by
1314 * interactivity modifiers. Will be RT if the task got
1315 * RT-boosted. If not then it returns p->normal_prio.
1317 static int effective_prio(struct task_struct *p)
1319 p->normal_prio = normal_prio(p);
1321 * If we are RT tasks or we were boosted to RT priority,
1322 * keep the priority unchanged. Otherwise, update priority
1323 * to the normal priority:
1325 if (!rt_prio(p->prio))
1326 return p->normal_prio;
1331 * activate_task - move a task to the runqueue.
1333 static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
1335 if (p->state == TASK_UNINTERRUPTIBLE)
1336 rq->nr_uninterruptible--;
1338 enqueue_task(rq, p, wakeup);
1339 inc_nr_running(p, rq);
1343 * deactivate_task - remove a task from the runqueue.
1345 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
1347 if (p->state == TASK_UNINTERRUPTIBLE)
1348 rq->nr_uninterruptible++;
1350 dequeue_task(rq, p, sleep);
1351 dec_nr_running(p, rq);
1355 * task_curr - is this task currently executing on a CPU?
1356 * @p: the task in question.
1358 inline int task_curr(const struct task_struct *p)
1360 return cpu_curr(task_cpu(p)) == p;
1363 /* Used instead of source_load when we know the type == 0 */
1364 unsigned long weighted_cpuload(const int cpu)
1366 return cpu_rq(cpu)->load.weight;
1369 static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
1371 set_task_rq(p, cpu);
1374 * After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
1375 * successfuly executed on another CPU. We must ensure that updates of
1376 * per-task data have been completed by this moment.
1379 task_thread_info(p)->cpu = cpu;
1383 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
1384 const struct sched_class *prev_class,
1385 int oldprio, int running)
1387 if (prev_class != p->sched_class) {
1388 if (prev_class->switched_from)
1389 prev_class->switched_from(rq, p, running);
1390 p->sched_class->switched_to(rq, p, running);
1392 p->sched_class->prio_changed(rq, p, oldprio, running);
1398 * Is this task likely cache-hot:
1401 task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
1405 if (p->sched_class != &fair_sched_class)
1408 if (sysctl_sched_migration_cost == -1)
1410 if (sysctl_sched_migration_cost == 0)
1413 delta = now - p->se.exec_start;
1415 return delta < (s64)sysctl_sched_migration_cost;
1419 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1421 int old_cpu = task_cpu(p);
1422 struct rq *old_rq = cpu_rq(old_cpu), *new_rq = cpu_rq(new_cpu);
1423 struct cfs_rq *old_cfsrq = task_cfs_rq(p),
1424 *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu);
1427 clock_offset = old_rq->clock - new_rq->clock;
1429 #ifdef CONFIG_SCHEDSTATS
1430 if (p->se.wait_start)
1431 p->se.wait_start -= clock_offset;
1432 if (p->se.sleep_start)
1433 p->se.sleep_start -= clock_offset;
1434 if (p->se.block_start)
1435 p->se.block_start -= clock_offset;
1436 if (old_cpu != new_cpu) {
1437 schedstat_inc(p, se.nr_migrations);
1438 if (task_hot(p, old_rq->clock, NULL))
1439 schedstat_inc(p, se.nr_forced2_migrations);
1442 p->se.vruntime -= old_cfsrq->min_vruntime -
1443 new_cfsrq->min_vruntime;
1445 __set_task_cpu(p, new_cpu);
1448 struct migration_req {
1449 struct list_head list;
1451 struct task_struct *task;
1454 struct completion done;
1458 * The task's runqueue lock must be held.
1459 * Returns true if you have to wait for migration thread.
1462 migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
1464 struct rq *rq = task_rq(p);
1467 * If the task is not on a runqueue (and not running), then
1468 * it is sufficient to simply update the task's cpu field.
1470 if (!p->se.on_rq && !task_running(rq, p)) {
1471 set_task_cpu(p, dest_cpu);
1475 init_completion(&req->done);
1477 req->dest_cpu = dest_cpu;
1478 list_add(&req->list, &rq->migration_queue);
1484 * wait_task_inactive - wait for a thread to unschedule.
1486 * The caller must ensure that the task *will* unschedule sometime soon,
1487 * else this function might spin for a *long* time. This function can't
1488 * be called with interrupts off, or it may introduce deadlock with
1489 * smp_call_function() if an IPI is sent by the same process we are
1490 * waiting to become inactive.
1492 void wait_task_inactive(struct task_struct *p)
1494 unsigned long flags;
1500 * We do the initial early heuristics without holding
1501 * any task-queue locks at all. We'll only try to get
1502 * the runqueue lock when things look like they will
1508 * If the task is actively running on another CPU
1509 * still, just relax and busy-wait without holding
1512 * NOTE! Since we don't hold any locks, it's not
1513 * even sure that "rq" stays as the right runqueue!
1514 * But we don't care, since "task_running()" will
1515 * return false if the runqueue has changed and p
1516 * is actually now running somewhere else!
1518 while (task_running(rq, p))
1522 * Ok, time to look more closely! We need the rq
1523 * lock now, to be *sure*. If we're wrong, we'll
1524 * just go back and repeat.
1526 rq = task_rq_lock(p, &flags);
1527 running = task_running(rq, p);
1528 on_rq = p->se.on_rq;
1529 task_rq_unlock(rq, &flags);
1532 * Was it really running after all now that we
1533 * checked with the proper locks actually held?
1535 * Oops. Go back and try again..
1537 if (unlikely(running)) {
1543 * It's not enough that it's not actively running,
1544 * it must be off the runqueue _entirely_, and not
1547 * So if it wa still runnable (but just not actively
1548 * running right now), it's preempted, and we should
1549 * yield - it could be a while.
1551 if (unlikely(on_rq)) {
1552 schedule_timeout_uninterruptible(1);
1557 * Ahh, all good. It wasn't running, and it wasn't
1558 * runnable, which means that it will never become
1559 * running in the future either. We're all done!
1566 * kick_process - kick a running thread to enter/exit the kernel
1567 * @p: the to-be-kicked thread
1569 * Cause a process which is running on another CPU to enter
1570 * kernel-mode, without any delay. (to get signals handled.)
1572 * NOTE: this function doesnt have to take the runqueue lock,
1573 * because all it wants to ensure is that the remote task enters
1574 * the kernel. If the IPI races and the task has been migrated
1575 * to another CPU then no harm is done and the purpose has been
1578 void kick_process(struct task_struct *p)
1584 if ((cpu != smp_processor_id()) && task_curr(p))
1585 smp_send_reschedule(cpu);
1590 * Return a low guess at the load of a migration-source cpu weighted
1591 * according to the scheduling class and "nice" value.
1593 * We want to under-estimate the load of migration sources, to
1594 * balance conservatively.
1596 static unsigned long source_load(int cpu, int type)
1598 struct rq *rq = cpu_rq(cpu);
1599 unsigned long total = weighted_cpuload(cpu);
1604 return min(rq->cpu_load[type-1], total);
1608 * Return a high guess at the load of a migration-target cpu weighted
1609 * according to the scheduling class and "nice" value.
1611 static unsigned long target_load(int cpu, int type)
1613 struct rq *rq = cpu_rq(cpu);
1614 unsigned long total = weighted_cpuload(cpu);
1619 return max(rq->cpu_load[type-1], total);
1623 * Return the average load per task on the cpu's run queue
1625 static unsigned long cpu_avg_load_per_task(int cpu)
1627 struct rq *rq = cpu_rq(cpu);
1628 unsigned long total = weighted_cpuload(cpu);
1629 unsigned long n = rq->nr_running;
1631 return n ? total / n : SCHED_LOAD_SCALE;
1635 * find_idlest_group finds and returns the least busy CPU group within the
1638 static struct sched_group *
1639 find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
1641 struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
1642 unsigned long min_load = ULONG_MAX, this_load = 0;
1643 int load_idx = sd->forkexec_idx;
1644 int imbalance = 100 + (sd->imbalance_pct-100)/2;
1647 unsigned long load, avg_load;
1651 /* Skip over this group if it has no CPUs allowed */
1652 if (!cpus_intersects(group->cpumask, p->cpus_allowed))
1655 local_group = cpu_isset(this_cpu, group->cpumask);
1657 /* Tally up the load of all CPUs in the group */
1660 for_each_cpu_mask(i, group->cpumask) {
1661 /* Bias balancing toward cpus of our domain */
1663 load = source_load(i, load_idx);
1665 load = target_load(i, load_idx);
1670 /* Adjust by relative CPU power of the group */
1671 avg_load = sg_div_cpu_power(group,
1672 avg_load * SCHED_LOAD_SCALE);
1675 this_load = avg_load;
1677 } else if (avg_load < min_load) {
1678 min_load = avg_load;
1681 } while (group = group->next, group != sd->groups);
1683 if (!idlest || 100*this_load < imbalance*min_load)
1689 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1692 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
1695 unsigned long load, min_load = ULONG_MAX;
1699 /* Traverse only the allowed CPUs */
1700 cpus_and(tmp, group->cpumask, p->cpus_allowed);
1702 for_each_cpu_mask(i, tmp) {
1703 load = weighted_cpuload(i);
1705 if (load < min_load || (load == min_load && i == this_cpu)) {
1715 * sched_balance_self: balance the current task (running on cpu) in domains
1716 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1719 * Balance, ie. select the least loaded group.
1721 * Returns the target CPU number, or the same CPU if no balancing is needed.
1723 * preempt must be disabled.
1725 static int sched_balance_self(int cpu, int flag)
1727 struct task_struct *t = current;
1728 struct sched_domain *tmp, *sd = NULL;
1730 for_each_domain(cpu, tmp) {
1732 * If power savings logic is enabled for a domain, stop there.
1734 if (tmp->flags & SD_POWERSAVINGS_BALANCE)
1736 if (tmp->flags & flag)
1742 struct sched_group *group;
1743 int new_cpu, weight;
1745 if (!(sd->flags & flag)) {
1751 group = find_idlest_group(sd, t, cpu);
1757 new_cpu = find_idlest_cpu(group, t, cpu);
1758 if (new_cpu == -1 || new_cpu == cpu) {
1759 /* Now try balancing at a lower domain level of cpu */
1764 /* Now try balancing at a lower domain level of new_cpu */
1767 weight = cpus_weight(span);
1768 for_each_domain(cpu, tmp) {
1769 if (weight <= cpus_weight(tmp->span))
1771 if (tmp->flags & flag)
1774 /* while loop will break here if sd == NULL */
1780 #endif /* CONFIG_SMP */
1783 * try_to_wake_up - wake up a thread
1784 * @p: the to-be-woken-up thread
1785 * @state: the mask of task states that can be woken
1786 * @sync: do a synchronous wakeup?
1788 * Put it on the run-queue if it's not already there. The "current"
1789 * thread is always on the run-queue (except when the actual
1790 * re-schedule is in progress), and as such you're allowed to do
1791 * the simpler "current->state = TASK_RUNNING" to mark yourself
1792 * runnable without the overhead of this.
1794 * returns failure only if the task is already active.
1796 static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
1798 int cpu, orig_cpu, this_cpu, success = 0;
1799 unsigned long flags;
1803 rq = task_rq_lock(p, &flags);
1804 old_state = p->state;
1805 if (!(old_state & state))
1813 this_cpu = smp_processor_id();
1816 if (unlikely(task_running(rq, p)))
1819 cpu = p->sched_class->select_task_rq(p, sync);
1820 if (cpu != orig_cpu) {
1821 set_task_cpu(p, cpu);
1822 task_rq_unlock(rq, &flags);
1823 /* might preempt at this point */
1824 rq = task_rq_lock(p, &flags);
1825 old_state = p->state;
1826 if (!(old_state & state))
1831 this_cpu = smp_processor_id();
1835 #ifdef CONFIG_SCHEDSTATS
1836 schedstat_inc(rq, ttwu_count);
1837 if (cpu == this_cpu)
1838 schedstat_inc(rq, ttwu_local);
1840 struct sched_domain *sd;
1841 for_each_domain(this_cpu, sd) {
1842 if (cpu_isset(cpu, sd->span)) {
1843 schedstat_inc(sd, ttwu_wake_remote);
1851 #endif /* CONFIG_SMP */
1852 schedstat_inc(p, se.nr_wakeups);
1854 schedstat_inc(p, se.nr_wakeups_sync);
1855 if (orig_cpu != cpu)
1856 schedstat_inc(p, se.nr_wakeups_migrate);
1857 if (cpu == this_cpu)
1858 schedstat_inc(p, se.nr_wakeups_local);
1860 schedstat_inc(p, se.nr_wakeups_remote);
1861 update_rq_clock(rq);
1862 activate_task(rq, p, 1);
1863 check_preempt_curr(rq, p);
1867 p->state = TASK_RUNNING;
1869 if (p->sched_class->task_wake_up)
1870 p->sched_class->task_wake_up(rq, p);
1873 task_rq_unlock(rq, &flags);
1878 int fastcall wake_up_process(struct task_struct *p)
1880 return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
1881 TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
1883 EXPORT_SYMBOL(wake_up_process);
1885 int fastcall wake_up_state(struct task_struct *p, unsigned int state)
1887 return try_to_wake_up(p, state, 0);
1891 * Perform scheduler related setup for a newly forked process p.
1892 * p is forked by current.
1894 * __sched_fork() is basic setup used by init_idle() too:
1896 static void __sched_fork(struct task_struct *p)
1898 p->se.exec_start = 0;
1899 p->se.sum_exec_runtime = 0;
1900 p->se.prev_sum_exec_runtime = 0;
1902 #ifdef CONFIG_SCHEDSTATS
1903 p->se.wait_start = 0;
1904 p->se.sum_sleep_runtime = 0;
1905 p->se.sleep_start = 0;
1906 p->se.block_start = 0;
1907 p->se.sleep_max = 0;
1908 p->se.block_max = 0;
1910 p->se.slice_max = 0;
1914 INIT_LIST_HEAD(&p->rt.run_list);
1917 #ifdef CONFIG_PREEMPT_NOTIFIERS
1918 INIT_HLIST_HEAD(&p->preempt_notifiers);
1922 * We mark the process as running here, but have not actually
1923 * inserted it onto the runqueue yet. This guarantees that
1924 * nobody will actually run it, and a signal or other external
1925 * event cannot wake it up and insert it on the runqueue either.
1927 p->state = TASK_RUNNING;
1931 * fork()/clone()-time setup:
1933 void sched_fork(struct task_struct *p, int clone_flags)
1935 int cpu = get_cpu();
1940 cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
1942 set_task_cpu(p, cpu);
1945 * Make sure we do not leak PI boosting priority to the child:
1947 p->prio = current->normal_prio;
1948 if (!rt_prio(p->prio))
1949 p->sched_class = &fair_sched_class;
1951 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1952 if (likely(sched_info_on()))
1953 memset(&p->sched_info, 0, sizeof(p->sched_info));
1955 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1958 #ifdef CONFIG_PREEMPT
1959 /* Want to start with kernel preemption disabled. */
1960 task_thread_info(p)->preempt_count = 1;
1966 * wake_up_new_task - wake up a newly created task for the first time.
1968 * This function will do some initial scheduler statistics housekeeping
1969 * that must be done for every newly created context, then puts the task
1970 * on the runqueue and wakes it.
1972 void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
1974 unsigned long flags;
1977 rq = task_rq_lock(p, &flags);
1978 BUG_ON(p->state != TASK_RUNNING);
1979 update_rq_clock(rq);
1981 p->prio = effective_prio(p);
1983 if (!p->sched_class->task_new || !current->se.on_rq) {
1984 activate_task(rq, p, 0);
1987 * Let the scheduling class do new task startup
1988 * management (if any):
1990 p->sched_class->task_new(rq, p);
1991 inc_nr_running(p, rq);
1993 check_preempt_curr(rq, p);
1995 if (p->sched_class->task_wake_up)
1996 p->sched_class->task_wake_up(rq, p);
1998 task_rq_unlock(rq, &flags);
2001 #ifdef CONFIG_PREEMPT_NOTIFIERS
2004 * preempt_notifier_register - tell me when current is being being preempted & rescheduled
2005 * @notifier: notifier struct to register
2007 void preempt_notifier_register(struct preempt_notifier *notifier)
2009 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2011 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2014 * preempt_notifier_unregister - no longer interested in preemption notifications
2015 * @notifier: notifier struct to unregister
2017 * This is safe to call from within a preemption notifier.
2019 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2021 hlist_del(¬ifier->link);
2023 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2025 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2027 struct preempt_notifier *notifier;
2028 struct hlist_node *node;
2030 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2031 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2035 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2036 struct task_struct *next)
2038 struct preempt_notifier *notifier;
2039 struct hlist_node *node;
2041 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2042 notifier->ops->sched_out(notifier, next);
2047 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2052 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2053 struct task_struct *next)
2060 * prepare_task_switch - prepare to switch tasks
2061 * @rq: the runqueue preparing to switch
2062 * @prev: the current task that is being switched out
2063 * @next: the task we are going to switch to.
2065 * This is called with the rq lock held and interrupts off. It must
2066 * be paired with a subsequent finish_task_switch after the context
2069 * prepare_task_switch sets up locking and calls architecture specific
2073 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2074 struct task_struct *next)
2076 fire_sched_out_preempt_notifiers(prev, next);
2077 prepare_lock_switch(rq, next);
2078 prepare_arch_switch(next);
2082 * finish_task_switch - clean up after a task-switch
2083 * @rq: runqueue associated with task-switch
2084 * @prev: the thread we just switched away from.
2086 * finish_task_switch must be called after the context switch, paired
2087 * with a prepare_task_switch call before the context switch.
2088 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2089 * and do any other architecture-specific cleanup actions.
2091 * Note that we may have delayed dropping an mm in context_switch(). If
2092 * so, we finish that here outside of the runqueue lock. (Doing it
2093 * with the lock held can cause deadlocks; see schedule() for
2096 static void finish_task_switch(struct rq *rq, struct task_struct *prev)
2097 __releases(rq->lock)
2099 struct mm_struct *mm = rq->prev_mm;
2105 * A task struct has one reference for the use as "current".
2106 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2107 * schedule one last time. The schedule call will never return, and
2108 * the scheduled task must drop that reference.
2109 * The test for TASK_DEAD must occur while the runqueue locks are
2110 * still held, otherwise prev could be scheduled on another cpu, die
2111 * there before we look at prev->state, and then the reference would
2113 * Manfred Spraul <manfred@colorfullife.com>
2115 prev_state = prev->state;
2116 finish_arch_switch(prev);
2117 finish_lock_switch(rq, prev);
2119 if (current->sched_class->post_schedule)
2120 current->sched_class->post_schedule(rq);
2123 fire_sched_in_preempt_notifiers(current);
2126 if (unlikely(prev_state == TASK_DEAD)) {
2128 * Remove function-return probe instances associated with this
2129 * task and put them back on the free list.
2131 kprobe_flush_task(prev);
2132 put_task_struct(prev);
2137 * schedule_tail - first thing a freshly forked thread must call.
2138 * @prev: the thread we just switched away from.
2140 asmlinkage void schedule_tail(struct task_struct *prev)
2141 __releases(rq->lock)
2143 struct rq *rq = this_rq();
2145 finish_task_switch(rq, prev);
2146 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2147 /* In this case, finish_task_switch does not reenable preemption */
2150 if (current->set_child_tid)
2151 put_user(task_pid_vnr(current), current->set_child_tid);
2155 * context_switch - switch to the new MM and the new
2156 * thread's register state.
2159 context_switch(struct rq *rq, struct task_struct *prev,
2160 struct task_struct *next)
2162 struct mm_struct *mm, *oldmm;
2164 prepare_task_switch(rq, prev, next);
2166 oldmm = prev->active_mm;
2168 * For paravirt, this is coupled with an exit in switch_to to
2169 * combine the page table reload and the switch backend into
2172 arch_enter_lazy_cpu_mode();
2174 if (unlikely(!mm)) {
2175 next->active_mm = oldmm;
2176 atomic_inc(&oldmm->mm_count);
2177 enter_lazy_tlb(oldmm, next);
2179 switch_mm(oldmm, mm, next);
2181 if (unlikely(!prev->mm)) {
2182 prev->active_mm = NULL;
2183 rq->prev_mm = oldmm;
2186 * Since the runqueue lock will be released by the next
2187 * task (which is an invalid locking op but in the case
2188 * of the scheduler it's an obvious special-case), so we
2189 * do an early lockdep release here:
2191 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2192 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2195 /* Here we just switch the register state and the stack. */
2196 switch_to(prev, next, prev);
2200 * this_rq must be evaluated again because prev may have moved
2201 * CPUs since it called schedule(), thus the 'rq' on its stack
2202 * frame will be invalid.
2204 finish_task_switch(this_rq(), prev);
2208 * nr_running, nr_uninterruptible and nr_context_switches:
2210 * externally visible scheduler statistics: current number of runnable
2211 * threads, current number of uninterruptible-sleeping threads, total
2212 * number of context switches performed since bootup.
2214 unsigned long nr_running(void)
2216 unsigned long i, sum = 0;
2218 for_each_online_cpu(i)
2219 sum += cpu_rq(i)->nr_running;
2224 unsigned long nr_uninterruptible(void)
2226 unsigned long i, sum = 0;
2228 for_each_possible_cpu(i)
2229 sum += cpu_rq(i)->nr_uninterruptible;
2232 * Since we read the counters lockless, it might be slightly
2233 * inaccurate. Do not allow it to go below zero though:
2235 if (unlikely((long)sum < 0))
2241 unsigned long long nr_context_switches(void)
2244 unsigned long long sum = 0;
2246 for_each_possible_cpu(i)
2247 sum += cpu_rq(i)->nr_switches;
2252 unsigned long nr_iowait(void)
2254 unsigned long i, sum = 0;
2256 for_each_possible_cpu(i)
2257 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2262 unsigned long nr_active(void)
2264 unsigned long i, running = 0, uninterruptible = 0;
2266 for_each_online_cpu(i) {
2267 running += cpu_rq(i)->nr_running;
2268 uninterruptible += cpu_rq(i)->nr_uninterruptible;
2271 if (unlikely((long)uninterruptible < 0))
2272 uninterruptible = 0;
2274 return running + uninterruptible;
2278 * Update rq->cpu_load[] statistics. This function is usually called every
2279 * scheduler tick (TICK_NSEC).
2281 static void update_cpu_load(struct rq *this_rq)
2283 unsigned long this_load = this_rq->load.weight;
2286 this_rq->nr_load_updates++;
2288 /* Update our load: */
2289 for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
2290 unsigned long old_load, new_load;
2292 /* scale is effectively 1 << i now, and >> i divides by scale */
2294 old_load = this_rq->cpu_load[i];
2295 new_load = this_load;
2297 * Round up the averaging division if load is increasing. This
2298 * prevents us from getting stuck on 9 if the load is 10, for
2301 if (new_load > old_load)
2302 new_load += scale-1;
2303 this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
2310 * double_rq_lock - safely lock two runqueues
2312 * Note this does not disable interrupts like task_rq_lock,
2313 * you need to do so manually before calling.
2315 static void double_rq_lock(struct rq *rq1, struct rq *rq2)
2316 __acquires(rq1->lock)
2317 __acquires(rq2->lock)
2319 BUG_ON(!irqs_disabled());
2321 spin_lock(&rq1->lock);
2322 __acquire(rq2->lock); /* Fake it out ;) */
2325 spin_lock(&rq1->lock);
2326 spin_lock(&rq2->lock);
2328 spin_lock(&rq2->lock);
2329 spin_lock(&rq1->lock);
2332 update_rq_clock(rq1);
2333 update_rq_clock(rq2);
2337 * double_rq_unlock - safely unlock two runqueues
2339 * Note this does not restore interrupts like task_rq_unlock,
2340 * you need to do so manually after calling.
2342 static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
2343 __releases(rq1->lock)
2344 __releases(rq2->lock)
2346 spin_unlock(&rq1->lock);
2348 spin_unlock(&rq2->lock);
2350 __release(rq2->lock);
2354 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2356 static int double_lock_balance(struct rq *this_rq, struct rq *busiest)
2357 __releases(this_rq->lock)
2358 __acquires(busiest->lock)
2359 __acquires(this_rq->lock)
2363 if (unlikely(!irqs_disabled())) {
2364 /* printk() doesn't work good under rq->lock */
2365 spin_unlock(&this_rq->lock);
2368 if (unlikely(!spin_trylock(&busiest->lock))) {
2369 if (busiest < this_rq) {
2370 spin_unlock(&this_rq->lock);
2371 spin_lock(&busiest->lock);
2372 spin_lock(&this_rq->lock);
2375 spin_lock(&busiest->lock);
2381 * If dest_cpu is allowed for this process, migrate the task to it.
2382 * This is accomplished by forcing the cpu_allowed mask to only
2383 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2384 * the cpu_allowed mask is restored.
2386 static void sched_migrate_task(struct task_struct *p, int dest_cpu)
2388 struct migration_req req;
2389 unsigned long flags;
2392 rq = task_rq_lock(p, &flags);
2393 if (!cpu_isset(dest_cpu, p->cpus_allowed)
2394 || unlikely(cpu_is_offline(dest_cpu)))
2397 /* force the process onto the specified CPU */
2398 if (migrate_task(p, dest_cpu, &req)) {
2399 /* Need to wait for migration thread (might exit: take ref). */
2400 struct task_struct *mt = rq->migration_thread;
2402 get_task_struct(mt);
2403 task_rq_unlock(rq, &flags);
2404 wake_up_process(mt);
2405 put_task_struct(mt);
2406 wait_for_completion(&req.done);
2411 task_rq_unlock(rq, &flags);
2415 * sched_exec - execve() is a valuable balancing opportunity, because at
2416 * this point the task has the smallest effective memory and cache footprint.
2418 void sched_exec(void)
2420 int new_cpu, this_cpu = get_cpu();
2421 new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
2423 if (new_cpu != this_cpu)
2424 sched_migrate_task(current, new_cpu);
2428 * pull_task - move a task from a remote runqueue to the local runqueue.
2429 * Both runqueues must be locked.
2431 static void pull_task(struct rq *src_rq, struct task_struct *p,
2432 struct rq *this_rq, int this_cpu)
2434 deactivate_task(src_rq, p, 0);
2435 set_task_cpu(p, this_cpu);
2436 activate_task(this_rq, p, 0);
2438 * Note that idle threads have a prio of MAX_PRIO, for this test
2439 * to be always true for them.
2441 check_preempt_curr(this_rq, p);
2445 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2448 int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
2449 struct sched_domain *sd, enum cpu_idle_type idle,
2453 * We do not migrate tasks that are:
2454 * 1) running (obviously), or
2455 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2456 * 3) are cache-hot on their current CPU.
2458 if (!cpu_isset(this_cpu, p->cpus_allowed)) {
2459 schedstat_inc(p, se.nr_failed_migrations_affine);
2464 if (task_running(rq, p)) {
2465 schedstat_inc(p, se.nr_failed_migrations_running);
2470 * Aggressive migration if:
2471 * 1) task is cache cold, or
2472 * 2) too many balance attempts have failed.
2475 if (!task_hot(p, rq->clock, sd) ||
2476 sd->nr_balance_failed > sd->cache_nice_tries) {
2477 #ifdef CONFIG_SCHEDSTATS
2478 if (task_hot(p, rq->clock, sd)) {
2479 schedstat_inc(sd, lb_hot_gained[idle]);
2480 schedstat_inc(p, se.nr_forced_migrations);
2486 if (task_hot(p, rq->clock, sd)) {
2487 schedstat_inc(p, se.nr_failed_migrations_hot);
2493 static unsigned long
2494 balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2495 unsigned long max_load_move, struct sched_domain *sd,
2496 enum cpu_idle_type idle, int *all_pinned,
2497 int *this_best_prio, struct rq_iterator *iterator)
2499 int loops = 0, pulled = 0, pinned = 0, skip_for_load;
2500 struct task_struct *p;
2501 long rem_load_move = max_load_move;
2503 if (max_load_move == 0)
2509 * Start the load-balancing iterator:
2511 p = iterator->start(iterator->arg);
2513 if (!p || loops++ > sysctl_sched_nr_migrate)
2516 * To help distribute high priority tasks across CPUs we don't
2517 * skip a task if it will be the highest priority task (i.e. smallest
2518 * prio value) on its new queue regardless of its load weight
2520 skip_for_load = (p->se.load.weight >> 1) > rem_load_move +
2521 SCHED_LOAD_SCALE_FUZZ;
2522 if ((skip_for_load && p->prio >= *this_best_prio) ||
2523 !can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
2524 p = iterator->next(iterator->arg);
2528 pull_task(busiest, p, this_rq, this_cpu);
2530 rem_load_move -= p->se.load.weight;
2533 * We only want to steal up to the prescribed amount of weighted load.
2535 if (rem_load_move > 0) {
2536 if (p->prio < *this_best_prio)
2537 *this_best_prio = p->prio;
2538 p = iterator->next(iterator->arg);
2543 * Right now, this is one of only two places pull_task() is called,
2544 * so we can safely collect pull_task() stats here rather than
2545 * inside pull_task().
2547 schedstat_add(sd, lb_gained[idle], pulled);
2550 *all_pinned = pinned;
2552 return max_load_move - rem_load_move;
2556 * move_tasks tries to move up to max_load_move weighted load from busiest to
2557 * this_rq, as part of a balancing operation within domain "sd".
2558 * Returns 1 if successful and 0 otherwise.
2560 * Called with both runqueues locked.
2562 static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2563 unsigned long max_load_move,
2564 struct sched_domain *sd, enum cpu_idle_type idle,
2567 const struct sched_class *class = sched_class_highest;
2568 unsigned long total_load_moved = 0;
2569 int this_best_prio = this_rq->curr->prio;
2573 class->load_balance(this_rq, this_cpu, busiest,
2574 max_load_move - total_load_moved,
2575 sd, idle, all_pinned, &this_best_prio);
2576 class = class->next;
2577 } while (class && max_load_move > total_load_moved);
2579 return total_load_moved > 0;
2583 iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
2584 struct sched_domain *sd, enum cpu_idle_type idle,
2585 struct rq_iterator *iterator)
2587 struct task_struct *p = iterator->start(iterator->arg);
2591 if (can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
2592 pull_task(busiest, p, this_rq, this_cpu);
2594 * Right now, this is only the second place pull_task()
2595 * is called, so we can safely collect pull_task()
2596 * stats here rather than inside pull_task().
2598 schedstat_inc(sd, lb_gained[idle]);
2602 p = iterator->next(iterator->arg);
2609 * move_one_task tries to move exactly one task from busiest to this_rq, as
2610 * part of active balancing operations within "domain".
2611 * Returns 1 if successful and 0 otherwise.
2613 * Called with both runqueues locked.
2615 static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
2616 struct sched_domain *sd, enum cpu_idle_type idle)
2618 const struct sched_class *class;
2620 for (class = sched_class_highest; class; class = class->next)
2621 if (class->move_one_task(this_rq, this_cpu, busiest, sd, idle))
2628 * find_busiest_group finds and returns the busiest CPU group within the
2629 * domain. It calculates and returns the amount of weighted load which
2630 * should be moved to restore balance via the imbalance parameter.
2632 static struct sched_group *
2633 find_busiest_group(struct sched_domain *sd, int this_cpu,
2634 unsigned long *imbalance, enum cpu_idle_type idle,
2635 int *sd_idle, cpumask_t *cpus, int *balance)
2637 struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
2638 unsigned long max_load, avg_load, total_load, this_load, total_pwr;
2639 unsigned long max_pull;
2640 unsigned long busiest_load_per_task, busiest_nr_running;
2641 unsigned long this_load_per_task, this_nr_running;
2642 int load_idx, group_imb = 0;
2643 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2644 int power_savings_balance = 1;
2645 unsigned long leader_nr_running = 0, min_load_per_task = 0;
2646 unsigned long min_nr_running = ULONG_MAX;
2647 struct sched_group *group_min = NULL, *group_leader = NULL;
2650 max_load = this_load = total_load = total_pwr = 0;
2651 busiest_load_per_task = busiest_nr_running = 0;
2652 this_load_per_task = this_nr_running = 0;
2653 if (idle == CPU_NOT_IDLE)
2654 load_idx = sd->busy_idx;
2655 else if (idle == CPU_NEWLY_IDLE)
2656 load_idx = sd->newidle_idx;
2658 load_idx = sd->idle_idx;
2661 unsigned long load, group_capacity, max_cpu_load, min_cpu_load;
2664 int __group_imb = 0;
2665 unsigned int balance_cpu = -1, first_idle_cpu = 0;
2666 unsigned long sum_nr_running, sum_weighted_load;
2668 local_group = cpu_isset(this_cpu, group->cpumask);
2671 balance_cpu = first_cpu(group->cpumask);
2673 /* Tally up the load of all CPUs in the group */
2674 sum_weighted_load = sum_nr_running = avg_load = 0;
2676 min_cpu_load = ~0UL;
2678 for_each_cpu_mask(i, group->cpumask) {
2681 if (!cpu_isset(i, *cpus))
2686 if (*sd_idle && rq->nr_running)
2689 /* Bias balancing toward cpus of our domain */
2691 if (idle_cpu(i) && !first_idle_cpu) {
2696 load = target_load(i, load_idx);
2698 load = source_load(i, load_idx);
2699 if (load > max_cpu_load)
2700 max_cpu_load = load;
2701 if (min_cpu_load > load)
2702 min_cpu_load = load;
2706 sum_nr_running += rq->nr_running;
2707 sum_weighted_load += weighted_cpuload(i);
2711 * First idle cpu or the first cpu(busiest) in this sched group
2712 * is eligible for doing load balancing at this and above
2713 * domains. In the newly idle case, we will allow all the cpu's
2714 * to do the newly idle load balance.
2716 if (idle != CPU_NEWLY_IDLE && local_group &&
2717 balance_cpu != this_cpu && balance) {
2722 total_load += avg_load;
2723 total_pwr += group->__cpu_power;
2725 /* Adjust by relative CPU power of the group */
2726 avg_load = sg_div_cpu_power(group,
2727 avg_load * SCHED_LOAD_SCALE);
2729 if ((max_cpu_load - min_cpu_load) > SCHED_LOAD_SCALE)
2732 group_capacity = group->__cpu_power / SCHED_LOAD_SCALE;
2735 this_load = avg_load;
2737 this_nr_running = sum_nr_running;
2738 this_load_per_task = sum_weighted_load;
2739 } else if (avg_load > max_load &&
2740 (sum_nr_running > group_capacity || __group_imb)) {
2741 max_load = avg_load;
2743 busiest_nr_running = sum_nr_running;
2744 busiest_load_per_task = sum_weighted_load;
2745 group_imb = __group_imb;
2748 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2750 * Busy processors will not participate in power savings
2753 if (idle == CPU_NOT_IDLE ||
2754 !(sd->flags & SD_POWERSAVINGS_BALANCE))
2758 * If the local group is idle or completely loaded
2759 * no need to do power savings balance at this domain
2761 if (local_group && (this_nr_running >= group_capacity ||
2763 power_savings_balance = 0;
2766 * If a group is already running at full capacity or idle,
2767 * don't include that group in power savings calculations
2769 if (!power_savings_balance || sum_nr_running >= group_capacity
2774 * Calculate the group which has the least non-idle load.
2775 * This is the group from where we need to pick up the load
2778 if ((sum_nr_running < min_nr_running) ||
2779 (sum_nr_running == min_nr_running &&
2780 first_cpu(group->cpumask) <
2781 first_cpu(group_min->cpumask))) {
2783 min_nr_running = sum_nr_running;
2784 min_load_per_task = sum_weighted_load /
2789 * Calculate the group which is almost near its
2790 * capacity but still has some space to pick up some load
2791 * from other group and save more power
2793 if (sum_nr_running <= group_capacity - 1) {
2794 if (sum_nr_running > leader_nr_running ||
2795 (sum_nr_running == leader_nr_running &&
2796 first_cpu(group->cpumask) >
2797 first_cpu(group_leader->cpumask))) {
2798 group_leader = group;
2799 leader_nr_running = sum_nr_running;
2804 group = group->next;
2805 } while (group != sd->groups);
2807 if (!busiest || this_load >= max_load || busiest_nr_running == 0)
2810 avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
2812 if (this_load >= avg_load ||
2813 100*max_load <= sd->imbalance_pct*this_load)
2816 busiest_load_per_task /= busiest_nr_running;
2818 busiest_load_per_task = min(busiest_load_per_task, avg_load);
2821 * We're trying to get all the cpus to the average_load, so we don't
2822 * want to push ourselves above the average load, nor do we wish to
2823 * reduce the max loaded cpu below the average load, as either of these
2824 * actions would just result in more rebalancing later, and ping-pong
2825 * tasks around. Thus we look for the minimum possible imbalance.
2826 * Negative imbalances (*we* are more loaded than anyone else) will
2827 * be counted as no imbalance for these purposes -- we can't fix that
2828 * by pulling tasks to us. Be careful of negative numbers as they'll
2829 * appear as very large values with unsigned longs.
2831 if (max_load <= busiest_load_per_task)
2835 * In the presence of smp nice balancing, certain scenarios can have
2836 * max load less than avg load(as we skip the groups at or below
2837 * its cpu_power, while calculating max_load..)
2839 if (max_load < avg_load) {
2841 goto small_imbalance;
2844 /* Don't want to pull so many tasks that a group would go idle */
2845 max_pull = min(max_load - avg_load, max_load - busiest_load_per_task);
2847 /* How much load to actually move to equalise the imbalance */
2848 *imbalance = min(max_pull * busiest->__cpu_power,
2849 (avg_load - this_load) * this->__cpu_power)
2853 * if *imbalance is less than the average load per runnable task
2854 * there is no gaurantee that any tasks will be moved so we'll have
2855 * a think about bumping its value to force at least one task to be
2858 if (*imbalance < busiest_load_per_task) {
2859 unsigned long tmp, pwr_now, pwr_move;
2863 pwr_move = pwr_now = 0;
2865 if (this_nr_running) {
2866 this_load_per_task /= this_nr_running;
2867 if (busiest_load_per_task > this_load_per_task)
2870 this_load_per_task = SCHED_LOAD_SCALE;
2872 if (max_load - this_load + SCHED_LOAD_SCALE_FUZZ >=
2873 busiest_load_per_task * imbn) {
2874 *imbalance = busiest_load_per_task;
2879 * OK, we don't have enough imbalance to justify moving tasks,
2880 * however we may be able to increase total CPU power used by
2884 pwr_now += busiest->__cpu_power *
2885 min(busiest_load_per_task, max_load);
2886 pwr_now += this->__cpu_power *
2887 min(this_load_per_task, this_load);
2888 pwr_now /= SCHED_LOAD_SCALE;
2890 /* Amount of load we'd subtract */
2891 tmp = sg_div_cpu_power(busiest,
2892 busiest_load_per_task * SCHED_LOAD_SCALE);
2894 pwr_move += busiest->__cpu_power *
2895 min(busiest_load_per_task, max_load - tmp);
2897 /* Amount of load we'd add */
2898 if (max_load * busiest->__cpu_power <
2899 busiest_load_per_task * SCHED_LOAD_SCALE)
2900 tmp = sg_div_cpu_power(this,
2901 max_load * busiest->__cpu_power);
2903 tmp = sg_div_cpu_power(this,
2904 busiest_load_per_task * SCHED_LOAD_SCALE);
2905 pwr_move += this->__cpu_power *
2906 min(this_load_per_task, this_load + tmp);
2907 pwr_move /= SCHED_LOAD_SCALE;
2909 /* Move if we gain throughput */
2910 if (pwr_move > pwr_now)
2911 *imbalance = busiest_load_per_task;
2917 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2918 if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
2921 if (this == group_leader && group_leader != group_min) {
2922 *imbalance = min_load_per_task;
2932 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2935 find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
2936 unsigned long imbalance, cpumask_t *cpus)
2938 struct rq *busiest = NULL, *rq;
2939 unsigned long max_load = 0;
2942 for_each_cpu_mask(i, group->cpumask) {
2945 if (!cpu_isset(i, *cpus))
2949 wl = weighted_cpuload(i);
2951 if (rq->nr_running == 1 && wl > imbalance)
2954 if (wl > max_load) {
2964 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2965 * so long as it is large enough.
2967 #define MAX_PINNED_INTERVAL 512
2970 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2971 * tasks if there is an imbalance.
2973 static int load_balance(int this_cpu, struct rq *this_rq,
2974 struct sched_domain *sd, enum cpu_idle_type idle,
2977 int ld_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
2978 struct sched_group *group;
2979 unsigned long imbalance;
2981 cpumask_t cpus = CPU_MASK_ALL;
2982 unsigned long flags;
2985 * When power savings policy is enabled for the parent domain, idle
2986 * sibling can pick up load irrespective of busy siblings. In this case,
2987 * let the state of idle sibling percolate up as CPU_IDLE, instead of
2988 * portraying it as CPU_NOT_IDLE.
2990 if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
2991 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2994 schedstat_inc(sd, lb_count[idle]);
2997 group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
3004 schedstat_inc(sd, lb_nobusyg[idle]);
3008 busiest = find_busiest_queue(group, idle, imbalance, &cpus);
3010 schedstat_inc(sd, lb_nobusyq[idle]);
3014 BUG_ON(busiest == this_rq);
3016 schedstat_add(sd, lb_imbalance[idle], imbalance);
3019 if (busiest->nr_running > 1) {
3021 * Attempt to move tasks. If find_busiest_group has found
3022 * an imbalance but busiest->nr_running <= 1, the group is
3023 * still unbalanced. ld_moved simply stays zero, so it is
3024 * correctly treated as an imbalance.
3026 local_irq_save(flags);
3027 double_rq_lock(this_rq, busiest);
3028 ld_moved = move_tasks(this_rq, this_cpu, busiest,
3029 imbalance, sd, idle, &all_pinned);
3030 double_rq_unlock(this_rq, busiest);
3031 local_irq_restore(flags);
3034 * some other cpu did the load balance for us.
3036 if (ld_moved && this_cpu != smp_processor_id())
3037 resched_cpu(this_cpu);
3039 /* All tasks on this runqueue were pinned by CPU affinity */
3040 if (unlikely(all_pinned)) {
3041 cpu_clear(cpu_of(busiest), cpus);
3042 if (!cpus_empty(cpus))
3049 schedstat_inc(sd, lb_failed[idle]);
3050 sd->nr_balance_failed++;
3052 if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
3054 spin_lock_irqsave(&busiest->lock, flags);
3056 /* don't kick the migration_thread, if the curr
3057 * task on busiest cpu can't be moved to this_cpu
3059 if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) {
3060 spin_unlock_irqrestore(&busiest->lock, flags);
3062 goto out_one_pinned;
3065 if (!busiest->active_balance) {
3066 busiest->active_balance = 1;
3067 busiest->push_cpu = this_cpu;
3070 spin_unlock_irqrestore(&busiest->lock, flags);
3072 wake_up_process(busiest->migration_thread);
3075 * We've kicked active balancing, reset the failure
3078 sd->nr_balance_failed = sd->cache_nice_tries+1;
3081 sd->nr_balance_failed = 0;
3083 if (likely(!active_balance)) {
3084 /* We were unbalanced, so reset the balancing interval */
3085 sd->balance_interval = sd->min_interval;
3088 * If we've begun active balancing, start to back off. This
3089 * case may not be covered by the all_pinned logic if there
3090 * is only 1 task on the busy runqueue (because we don't call
3093 if (sd->balance_interval < sd->max_interval)
3094 sd->balance_interval *= 2;
3097 if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
3098 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3103 schedstat_inc(sd, lb_balanced[idle]);
3105 sd->nr_balance_failed = 0;
3108 /* tune up the balancing interval */
3109 if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
3110 (sd->balance_interval < sd->max_interval))
3111 sd->balance_interval *= 2;
3113 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
3114 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3120 * Check this_cpu to ensure it is balanced within domain. Attempt to move
3121 * tasks if there is an imbalance.
3123 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
3124 * this_rq is locked.
3127 load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
3129 struct sched_group *group;
3130 struct rq *busiest = NULL;
3131 unsigned long imbalance;
3135 cpumask_t cpus = CPU_MASK_ALL;
3138 * When power savings policy is enabled for the parent domain, idle
3139 * sibling can pick up load irrespective of busy siblings. In this case,
3140 * let the state of idle sibling percolate up as IDLE, instead of
3141 * portraying it as CPU_NOT_IDLE.
3143 if (sd->flags & SD_SHARE_CPUPOWER &&
3144 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3147 schedstat_inc(sd, lb_count[CPU_NEWLY_IDLE]);
3149 group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE,
3150 &sd_idle, &cpus, NULL);
3152 schedstat_inc(sd, lb_nobusyg[CPU_NEWLY_IDLE]);
3156 busiest = find_busiest_queue(group, CPU_NEWLY_IDLE, imbalance,
3159 schedstat_inc(sd, lb_nobusyq[CPU_NEWLY_IDLE]);
3163 BUG_ON(busiest == this_rq);
3165 schedstat_add(sd, lb_imbalance[CPU_NEWLY_IDLE], imbalance);
3168 if (busiest->nr_running > 1) {
3169 /* Attempt to move tasks */
3170 double_lock_balance(this_rq, busiest);
3171 /* this_rq->clock is already updated */
3172 update_rq_clock(busiest);
3173 ld_moved = move_tasks(this_rq, this_cpu, busiest,
3174 imbalance, sd, CPU_NEWLY_IDLE,
3176 spin_unlock(&busiest->lock);
3178 if (unlikely(all_pinned)) {
3179 cpu_clear(cpu_of(busiest), cpus);
3180 if (!cpus_empty(cpus))
3186 schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
3187 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
3188 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3191 sd->nr_balance_failed = 0;
3196 schedstat_inc(sd, lb_balanced[CPU_NEWLY_IDLE]);
3197 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
3198 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
3200 sd->nr_balance_failed = 0;
3206 * idle_balance is called by schedule() if this_cpu is about to become
3207 * idle. Attempts to pull tasks from other CPUs.
3209 static void idle_balance(int this_cpu, struct rq *this_rq)
3211 struct sched_domain *sd;
3212 int pulled_task = -1;
3213 unsigned long next_balance = jiffies + HZ;
3215 for_each_domain(this_cpu, sd) {
3216 unsigned long interval;
3218 if (!(sd->flags & SD_LOAD_BALANCE))
3221 if (sd->flags & SD_BALANCE_NEWIDLE)
3222 /* If we've pulled tasks over stop searching: */
3223 pulled_task = load_balance_newidle(this_cpu,
3226 interval = msecs_to_jiffies(sd->balance_interval);
3227 if (time_after(next_balance, sd->last_balance + interval))
3228 next_balance = sd->last_balance + interval;
3232 if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
3234 * We are going idle. next_balance may be set based on
3235 * a busy processor. So reset next_balance.
3237 this_rq->next_balance = next_balance;
3242 * active_load_balance is run by migration threads. It pushes running tasks
3243 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
3244 * running on each physical CPU where possible, and avoids physical /
3245 * logical imbalances.
3247 * Called with busiest_rq locked.
3249 static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
3251 int target_cpu = busiest_rq->push_cpu;
3252 struct sched_domain *sd;
3253 struct rq *target_rq;
3255 /* Is there any task to move? */
3256 if (busiest_rq->nr_running <= 1)
3259 target_rq = cpu_rq(target_cpu);
3262 * This condition is "impossible", if it occurs
3263 * we need to fix it. Originally reported by
3264 * Bjorn Helgaas on a 128-cpu setup.
3266 BUG_ON(busiest_rq == target_rq);
3268 /* move a task from busiest_rq to target_rq */
3269 double_lock_balance(busiest_rq, target_rq);
3270 update_rq_clock(busiest_rq);
3271 update_rq_clock(target_rq);
3273 /* Search for an sd spanning us and the target CPU. */
3274 for_each_domain(target_cpu, sd) {
3275 if ((sd->flags & SD_LOAD_BALANCE) &&
3276 cpu_isset(busiest_cpu, sd->span))
3281 schedstat_inc(sd, alb_count);
3283 if (move_one_task(target_rq, target_cpu, busiest_rq,
3285 schedstat_inc(sd, alb_pushed);
3287 schedstat_inc(sd, alb_failed);
3289 spin_unlock(&target_rq->lock);
3294 atomic_t load_balancer;
3296 } nohz ____cacheline_aligned = {
3297 .load_balancer = ATOMIC_INIT(-1),
3298 .cpu_mask = CPU_MASK_NONE,
3302 * This routine will try to nominate the ilb (idle load balancing)
3303 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
3304 * load balancing on behalf of all those cpus. If all the cpus in the system
3305 * go into this tickless mode, then there will be no ilb owner (as there is
3306 * no need for one) and all the cpus will sleep till the next wakeup event
3309 * For the ilb owner, tick is not stopped. And this tick will be used
3310 * for idle load balancing. ilb owner will still be part of
3313 * While stopping the tick, this cpu will become the ilb owner if there
3314 * is no other owner. And will be the owner till that cpu becomes busy
3315 * or if all cpus in the system stop their ticks at which point
3316 * there is no need for ilb owner.
3318 * When the ilb owner becomes busy, it nominates another owner, during the
3319 * next busy scheduler_tick()
3321 int select_nohz_load_balancer(int stop_tick)
3323 int cpu = smp_processor_id();
3326 cpu_set(cpu, nohz.cpu_mask);
3327 cpu_rq(cpu)->in_nohz_recently = 1;
3330 * If we are going offline and still the leader, give up!
3332 if (cpu_is_offline(cpu) &&
3333 atomic_read(&nohz.load_balancer) == cpu) {
3334 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
3339 /* time for ilb owner also to sleep */
3340 if (cpus_weight(nohz.cpu_mask) == num_online_cpus()) {
3341 if (atomic_read(&nohz.load_balancer) == cpu)
3342 atomic_set(&nohz.load_balancer, -1);
3346 if (atomic_read(&nohz.load_balancer) == -1) {
3347 /* make me the ilb owner */
3348 if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
3350 } else if (atomic_read(&nohz.load_balancer) == cpu)
3353 if (!cpu_isset(cpu, nohz.cpu_mask))
3356 cpu_clear(cpu, nohz.cpu_mask);
3358 if (atomic_read(&nohz.load_balancer) == cpu)
3359 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
3366 static DEFINE_SPINLOCK(balancing);
3369 * It checks each scheduling domain to see if it is due to be balanced,
3370 * and initiates a balancing operation if so.
3372 * Balancing parameters are set up in arch_init_sched_domains.
3374 static void rebalance_domains(int cpu, enum cpu_idle_type idle)
3377 struct rq *rq = cpu_rq(cpu);
3378 unsigned long interval;
3379 struct sched_domain *sd;
3380 /* Earliest time when we have to do rebalance again */
3381 unsigned long next_balance = jiffies + 60*HZ;
3382 int update_next_balance = 0;
3384 for_each_domain(cpu, sd) {
3385 if (!(sd->flags & SD_LOAD_BALANCE))
3388 interval = sd->balance_interval;
3389 if (idle != CPU_IDLE)
3390 interval *= sd->busy_factor;
3392 /* scale ms to jiffies */
3393 interval = msecs_to_jiffies(interval);
3394 if (unlikely(!interval))
3396 if (interval > HZ*NR_CPUS/10)
3397 interval = HZ*NR_CPUS/10;
3400 if (sd->flags & SD_SERIALIZE) {
3401 if (!spin_trylock(&balancing))
3405 if (time_after_eq(jiffies, sd->last_balance + interval)) {
3406 if (load_balance(cpu, rq, sd, idle, &balance)) {
3408 * We've pulled tasks over so either we're no
3409 * longer idle, or one of our SMT siblings is
3412 idle = CPU_NOT_IDLE;
3414 sd->last_balance = jiffies;
3416 if (sd->flags & SD_SERIALIZE)
3417 spin_unlock(&balancing);
3419 if (time_after(next_balance, sd->last_balance + interval)) {
3420 next_balance = sd->last_balance + interval;
3421 update_next_balance = 1;
3425 * Stop the load balance at this level. There is another
3426 * CPU in our sched group which is doing load balancing more
3434 * next_balance will be updated only when there is a need.
3435 * When the cpu is attached to null domain for ex, it will not be
3438 if (likely(update_next_balance))
3439 rq->next_balance = next_balance;
3443 * run_rebalance_domains is triggered when needed from the scheduler tick.
3444 * In CONFIG_NO_HZ case, the idle load balance owner will do the
3445 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3447 static void run_rebalance_domains(struct softirq_action *h)
3449 int this_cpu = smp_processor_id();
3450 struct rq *this_rq = cpu_rq(this_cpu);
3451 enum cpu_idle_type idle = this_rq->idle_at_tick ?
3452 CPU_IDLE : CPU_NOT_IDLE;
3454 rebalance_domains(this_cpu, idle);
3458 * If this cpu is the owner for idle load balancing, then do the
3459 * balancing on behalf of the other idle cpus whose ticks are
3462 if (this_rq->idle_at_tick &&
3463 atomic_read(&nohz.load_balancer) == this_cpu) {
3464 cpumask_t cpus = nohz.cpu_mask;
3468 cpu_clear(this_cpu, cpus);
3469 for_each_cpu_mask(balance_cpu, cpus) {
3471 * If this cpu gets work to do, stop the load balancing
3472 * work being done for other cpus. Next load
3473 * balancing owner will pick it up.
3478 rebalance_domains(balance_cpu, CPU_IDLE);
3480 rq = cpu_rq(balance_cpu);
3481 if (time_after(this_rq->next_balance, rq->next_balance))
3482 this_rq->next_balance = rq->next_balance;
3489 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3491 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3492 * idle load balancing owner or decide to stop the periodic load balancing,
3493 * if the whole system is idle.
3495 static inline void trigger_load_balance(struct rq *rq, int cpu)
3499 * If we were in the nohz mode recently and busy at the current
3500 * scheduler tick, then check if we need to nominate new idle
3503 if (rq->in_nohz_recently && !rq->idle_at_tick) {
3504 rq->in_nohz_recently = 0;
3506 if (atomic_read(&nohz.load_balancer) == cpu) {
3507 cpu_clear(cpu, nohz.cpu_mask);
3508 atomic_set(&nohz.load_balancer, -1);
3511 if (atomic_read(&nohz.load_balancer) == -1) {
3513 * simple selection for now: Nominate the
3514 * first cpu in the nohz list to be the next
3517 * TBD: Traverse the sched domains and nominate
3518 * the nearest cpu in the nohz.cpu_mask.
3520 int ilb = first_cpu(nohz.cpu_mask);
3528 * If this cpu is idle and doing idle load balancing for all the
3529 * cpus with ticks stopped, is it time for that to stop?
3531 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
3532 cpus_weight(nohz.cpu_mask) == num_online_cpus()) {
3538 * If this cpu is idle and the idle load balancing is done by
3539 * someone else, then no need raise the SCHED_SOFTIRQ
3541 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
3542 cpu_isset(cpu, nohz.cpu_mask))
3545 if (time_after_eq(jiffies, rq->next_balance))
3546 raise_softirq(SCHED_SOFTIRQ);
3549 #else /* CONFIG_SMP */
3552 * on UP we do not need to balance between CPUs:
3554 static inline void idle_balance(int cpu, struct rq *rq)
3560 DEFINE_PER_CPU(struct kernel_stat, kstat);
3562 EXPORT_PER_CPU_SYMBOL(kstat);
3565 * Return p->sum_exec_runtime plus any more ns on the sched_clock
3566 * that have not yet been banked in case the task is currently running.
3568 unsigned long long task_sched_runtime(struct task_struct *p)
3570 unsigned long flags;
3574 rq = task_rq_lock(p, &flags);
3575 ns = p->se.sum_exec_runtime;
3576 if (task_current(rq, p)) {
3577 update_rq_clock(rq);
3578 delta_exec = rq->clock - p->se.exec_start;
3579 if ((s64)delta_exec > 0)
3582 task_rq_unlock(rq, &flags);
3588 * Account user cpu time to a process.
3589 * @p: the process that the cpu time gets accounted to
3590 * @cputime: the cpu time spent in user space since the last update
3592 void account_user_time(struct task_struct *p, cputime_t cputime)
3594 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3597 p->utime = cputime_add(p->utime, cputime);
3599 /* Add user time to cpustat. */
3600 tmp = cputime_to_cputime64(cputime);
3601 if (TASK_NICE(p) > 0)
3602 cpustat->nice = cputime64_add(cpustat->nice, tmp);
3604 cpustat->user = cputime64_add(cpustat->user, tmp);
3608 * Account guest cpu time to a process.
3609 * @p: the process that the cpu time gets accounted to
3610 * @cputime: the cpu time spent in virtual machine since the last update
3612 static void account_guest_time(struct task_struct *p, cputime_t cputime)
3615 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3617 tmp = cputime_to_cputime64(cputime);
3619 p->utime = cputime_add(p->utime, cputime);
3620 p->gtime = cputime_add(p->gtime, cputime);
3622 cpustat->user = cputime64_add(cpustat->user, tmp);
3623 cpustat->guest = cputime64_add(cpustat->guest, tmp);
3627 * Account scaled user cpu time to a process.
3628 * @p: the process that the cpu time gets accounted to
3629 * @cputime: the cpu time spent in user space since the last update
3631 void account_user_time_scaled(struct task_struct *p, cputime_t cputime)
3633 p->utimescaled = cputime_add(p->utimescaled, cputime);
3637 * Account system cpu time to a process.
3638 * @p: the process that the cpu time gets accounted to
3639 * @hardirq_offset: the offset to subtract from hardirq_count()
3640 * @cputime: the cpu time spent in kernel space since the last update
3642 void account_system_time(struct task_struct *p, int hardirq_offset,
3645 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3646 struct rq *rq = this_rq();
3649 if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0))
3650 return account_guest_time(p, cputime);
3652 p->stime = cputime_add(p->stime, cputime);
3654 /* Add system time to cpustat. */
3655 tmp = cputime_to_cputime64(cputime);
3656 if (hardirq_count() - hardirq_offset)
3657 cpustat->irq = cputime64_add(cpustat->irq, tmp);
3658 else if (softirq_count())
3659 cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
3660 else if (p != rq->idle)
3661 cpustat->system = cputime64_add(cpustat->system, tmp);
3662 else if (atomic_read(&rq->nr_iowait) > 0)
3663 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
3665 cpustat->idle = cputime64_add(cpustat->idle, tmp);
3666 /* Account for system time used */
3667 acct_update_integrals(p);
3671 * Account scaled system cpu time to a process.
3672 * @p: the process that the cpu time gets accounted to
3673 * @hardirq_offset: the offset to subtract from hardirq_count()
3674 * @cputime: the cpu time spent in kernel space since the last update
3676 void account_system_time_scaled(struct task_struct *p, cputime_t cputime)
3678 p->stimescaled = cputime_add(p->stimescaled, cputime);
3682 * Account for involuntary wait time.
3683 * @p: the process from which the cpu time has been stolen
3684 * @steal: the cpu time spent in involuntary wait
3686 void account_steal_time(struct task_struct *p, cputime_t steal)
3688 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3689 cputime64_t tmp = cputime_to_cputime64(steal);
3690 struct rq *rq = this_rq();
3692 if (p == rq->idle) {
3693 p->stime = cputime_add(p->stime, steal);
3694 if (atomic_read(&rq->nr_iowait) > 0)
3695 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
3697 cpustat->idle = cputime64_add(cpustat->idle, tmp);
3699 cpustat->steal = cputime64_add(cpustat->steal, tmp);
3703 * This function gets called by the timer code, with HZ frequency.
3704 * We call it with interrupts disabled.
3706 * It also gets called by the fork code, when changing the parent's
3709 void scheduler_tick(void)
3711 int cpu = smp_processor_id();
3712 struct rq *rq = cpu_rq(cpu);
3713 struct task_struct *curr = rq->curr;
3714 u64 next_tick = rq->tick_timestamp + TICK_NSEC;
3716 spin_lock(&rq->lock);
3717 __update_rq_clock(rq);
3719 * Let rq->clock advance by at least TICK_NSEC:
3721 if (unlikely(rq->clock < next_tick))
3722 rq->clock = next_tick;
3723 rq->tick_timestamp = rq->clock;
3724 update_cpu_load(rq);
3725 curr->sched_class->task_tick(rq, curr, 0);
3726 update_sched_rt_period(rq);
3727 spin_unlock(&rq->lock);
3730 rq->idle_at_tick = idle_cpu(cpu);
3731 trigger_load_balance(rq, cpu);
3735 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3737 void fastcall add_preempt_count(int val)
3742 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3744 preempt_count() += val;
3746 * Spinlock count overflowing soon?
3748 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
3751 EXPORT_SYMBOL(add_preempt_count);
3753 void fastcall sub_preempt_count(int val)
3758 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3761 * Is the spinlock portion underflowing?
3763 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3764 !(preempt_count() & PREEMPT_MASK)))
3767 preempt_count() -= val;
3769 EXPORT_SYMBOL(sub_preempt_count);
3774 * Print scheduling while atomic bug:
3776 static noinline void __schedule_bug(struct task_struct *prev)
3778 struct pt_regs *regs = get_irq_regs();
3780 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
3781 prev->comm, prev->pid, preempt_count());
3783 debug_show_held_locks(prev);
3784 if (irqs_disabled())
3785 print_irqtrace_events(prev);
3794 * Various schedule()-time debugging checks and statistics:
3796 static inline void schedule_debug(struct task_struct *prev)
3799 * Test if we are atomic. Since do_exit() needs to call into
3800 * schedule() atomically, we ignore that path for now.
3801 * Otherwise, whine if we are scheduling when we should not be.
3803 if (unlikely(in_atomic_preempt_off()) && unlikely(!prev->exit_state))
3804 __schedule_bug(prev);
3806 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3808 schedstat_inc(this_rq(), sched_count);
3809 #ifdef CONFIG_SCHEDSTATS
3810 if (unlikely(prev->lock_depth >= 0)) {
3811 schedstat_inc(this_rq(), bkl_count);
3812 schedstat_inc(prev, sched_info.bkl_count);
3818 * Pick up the highest-prio task:
3820 static inline struct task_struct *
3821 pick_next_task(struct rq *rq, struct task_struct *prev)
3823 const struct sched_class *class;
3824 struct task_struct *p;
3827 * Optimization: we know that if all tasks are in
3828 * the fair class we can call that function directly:
3830 if (likely(rq->nr_running == rq->cfs.nr_running)) {
3831 p = fair_sched_class.pick_next_task(rq);
3836 class = sched_class_highest;
3838 p = class->pick_next_task(rq);
3842 * Will never be NULL as the idle class always
3843 * returns a non-NULL p:
3845 class = class->next;
3850 * schedule() is the main scheduler function.
3852 asmlinkage void __sched schedule(void)
3854 struct task_struct *prev, *next;
3861 cpu = smp_processor_id();
3865 switch_count = &prev->nivcsw;
3867 release_kernel_lock(prev);
3868 need_resched_nonpreemptible:
3870 schedule_debug(prev);
3875 * Do the rq-clock update outside the rq lock:
3877 local_irq_disable();
3878 __update_rq_clock(rq);
3879 spin_lock(&rq->lock);
3880 clear_tsk_need_resched(prev);
3882 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
3883 if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
3884 unlikely(signal_pending(prev)))) {
3885 prev->state = TASK_RUNNING;
3887 deactivate_task(rq, prev, 1);
3889 switch_count = &prev->nvcsw;
3893 if (prev->sched_class->pre_schedule)
3894 prev->sched_class->pre_schedule(rq, prev);
3897 if (unlikely(!rq->nr_running))
3898 idle_balance(cpu, rq);
3900 prev->sched_class->put_prev_task(rq, prev);
3901 next = pick_next_task(rq, prev);
3903 sched_info_switch(prev, next);
3905 if (likely(prev != next)) {
3910 context_switch(rq, prev, next); /* unlocks the rq */
3912 * the context switch might have flipped the stack from under
3913 * us, hence refresh the local variables.
3915 cpu = smp_processor_id();
3918 spin_unlock_irq(&rq->lock);
3922 if (unlikely(reacquire_kernel_lock(current) < 0))
3923 goto need_resched_nonpreemptible;
3925 preempt_enable_no_resched();
3926 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3929 EXPORT_SYMBOL(schedule);
3931 #ifdef CONFIG_PREEMPT
3933 * this is the entry point to schedule() from in-kernel preemption
3934 * off of preempt_enable. Kernel preemptions off return from interrupt
3935 * occur there and call schedule directly.
3937 asmlinkage void __sched preempt_schedule(void)
3939 struct thread_info *ti = current_thread_info();
3940 #ifdef CONFIG_PREEMPT_BKL
3941 struct task_struct *task = current;
3942 int saved_lock_depth;
3945 * If there is a non-zero preempt_count or interrupts are disabled,
3946 * we do not want to preempt the current task. Just return..
3948 if (likely(ti->preempt_count || irqs_disabled()))
3952 add_preempt_count(PREEMPT_ACTIVE);
3955 * We keep the big kernel semaphore locked, but we
3956 * clear ->lock_depth so that schedule() doesnt
3957 * auto-release the semaphore:
3959 #ifdef CONFIG_PREEMPT_BKL
3960 saved_lock_depth = task->lock_depth;
3961 task->lock_depth = -1;
3964 #ifdef CONFIG_PREEMPT_BKL
3965 task->lock_depth = saved_lock_depth;
3967 sub_preempt_count(PREEMPT_ACTIVE);
3970 * Check again in case we missed a preemption opportunity
3971 * between schedule and now.
3974 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED)));
3976 EXPORT_SYMBOL(preempt_schedule);
3979 * this is the entry point to schedule() from kernel preemption
3980 * off of irq context.
3981 * Note, that this is called and return with irqs disabled. This will
3982 * protect us against recursive calling from irq.
3984 asmlinkage void __sched preempt_schedule_irq(void)
3986 struct thread_info *ti = current_thread_info();
3987 #ifdef CONFIG_PREEMPT_BKL
3988 struct task_struct *task = current;
3989 int saved_lock_depth;
3991 /* Catch callers which need to be fixed */
3992 BUG_ON(ti->preempt_count || !irqs_disabled());
3995 add_preempt_count(PREEMPT_ACTIVE);
3998 * We keep the big kernel semaphore locked, but we
3999 * clear ->lock_depth so that schedule() doesnt
4000 * auto-release the semaphore:
4002 #ifdef CONFIG_PREEMPT_BKL
4003 saved_lock_depth = task->lock_depth;
4004 task->lock_depth = -1;
4008 local_irq_disable();
4009 #ifdef CONFIG_PREEMPT_BKL
4010 task->lock_depth = saved_lock_depth;
4012 sub_preempt_count(PREEMPT_ACTIVE);
4015 * Check again in case we missed a preemption opportunity
4016 * between schedule and now.
4019 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED)));
4022 #endif /* CONFIG_PREEMPT */
4024 int default_wake_function(wait_queue_t *curr, unsigned mode, int sync,
4027 return try_to_wake_up(curr->private, mode, sync);
4029 EXPORT_SYMBOL(default_wake_function);
4032 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
4033 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
4034 * number) then we wake all the non-exclusive tasks and one exclusive task.
4036 * There are circumstances in which we can try to wake a task which has already
4037 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
4038 * zero in this (rare) case, and we handle it by continuing to scan the queue.
4040 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
4041 int nr_exclusive, int sync, void *key)
4043 wait_queue_t *curr, *next;
4045 list_for_each_entry_safe(curr, next, &q->task_list, task_list) {
4046 unsigned flags = curr->flags;
4048 if (curr->func(curr, mode, sync, key) &&
4049 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
4055 * __wake_up - wake up threads blocked on a waitqueue.
4057 * @mode: which threads
4058 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4059 * @key: is directly passed to the wakeup function
4061 void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
4062 int nr_exclusive, void *key)
4064 unsigned long flags;
4066 spin_lock_irqsave(&q->lock, flags);
4067 __wake_up_common(q, mode, nr_exclusive, 0, key);
4068 spin_unlock_irqrestore(&q->lock, flags);
4070 EXPORT_SYMBOL(__wake_up);
4073 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
4075 void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
4077 __wake_up_common(q, mode, 1, 0, NULL);
4081 * __wake_up_sync - wake up threads blocked on a waitqueue.
4083 * @mode: which threads
4084 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4086 * The sync wakeup differs that the waker knows that it will schedule
4087 * away soon, so while the target thread will be woken up, it will not
4088 * be migrated to another CPU - ie. the two threads are 'synchronized'
4089 * with each other. This can prevent needless bouncing between CPUs.
4091 * On UP it can prevent extra preemption.
4094 __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
4096 unsigned long flags;
4102 if (unlikely(!nr_exclusive))
4105 spin_lock_irqsave(&q->lock, flags);
4106 __wake_up_common(q, mode, nr_exclusive, sync, NULL);
4107 spin_unlock_irqrestore(&q->lock, flags);
4109 EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
4111 void complete(struct completion *x)
4113 unsigned long flags;
4115 spin_lock_irqsave(&x->wait.lock, flags);
4117 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
4119 spin_unlock_irqrestore(&x->wait.lock, flags);
4121 EXPORT_SYMBOL(complete);
4123 void complete_all(struct completion *x)
4125 unsigned long flags;
4127 spin_lock_irqsave(&x->wait.lock, flags);
4128 x->done += UINT_MAX/2;
4129 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
4131 spin_unlock_irqrestore(&x->wait.lock, flags);
4133 EXPORT_SYMBOL(complete_all);
4135 static inline long __sched
4136 do_wait_for_common(struct completion *x, long timeout, int state)
4139 DECLARE_WAITQUEUE(wait, current);
4141 wait.flags |= WQ_FLAG_EXCLUSIVE;
4142 __add_wait_queue_tail(&x->wait, &wait);
4144 if (state == TASK_INTERRUPTIBLE &&
4145 signal_pending(current)) {
4146 __remove_wait_queue(&x->wait, &wait);
4147 return -ERESTARTSYS;
4149 __set_current_state(state);
4150 spin_unlock_irq(&x->wait.lock);
4151 timeout = schedule_timeout(timeout);
4152 spin_lock_irq(&x->wait.lock);
4154 __remove_wait_queue(&x->wait, &wait);
4158 __remove_wait_queue(&x->wait, &wait);
4165 wait_for_common(struct completion *x, long timeout, int state)
4169 spin_lock_irq(&x->wait.lock);
4170 timeout = do_wait_for_common(x, timeout, state);
4171 spin_unlock_irq(&x->wait.lock);
4175 void __sched wait_for_completion(struct completion *x)
4177 wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
4179 EXPORT_SYMBOL(wait_for_completion);
4181 unsigned long __sched
4182 wait_for_completion_timeout(struct completion *x, unsigned long timeout)
4184 return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE);
4186 EXPORT_SYMBOL(wait_for_completion_timeout);
4188 int __sched wait_for_completion_interruptible(struct completion *x)
4190 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
4191 if (t == -ERESTARTSYS)
4195 EXPORT_SYMBOL(wait_for_completion_interruptible);
4197 unsigned long __sched
4198 wait_for_completion_interruptible_timeout(struct completion *x,
4199 unsigned long timeout)
4201 return wait_for_common(x, timeout, TASK_INTERRUPTIBLE);
4203 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
4206 sleep_on_common(wait_queue_head_t *q, int state, long timeout)
4208 unsigned long flags;
4211 init_waitqueue_entry(&wait, current);
4213 __set_current_state(state);
4215 spin_lock_irqsave(&q->lock, flags);
4216 __add_wait_queue(q, &wait);
4217 spin_unlock(&q->lock);
4218 timeout = schedule_timeout(timeout);
4219 spin_lock_irq(&q->lock);
4220 __remove_wait_queue(q, &wait);
4221 spin_unlock_irqrestore(&q->lock, flags);
4226 void __sched interruptible_sleep_on(wait_queue_head_t *q)
4228 sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
4230 EXPORT_SYMBOL(interruptible_sleep_on);
4233 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
4235 return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
4237 EXPORT_SYMBOL(interruptible_sleep_on_timeout);
4239 void __sched sleep_on(wait_queue_head_t *q)
4241 sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
4243 EXPORT_SYMBOL(sleep_on);
4245 long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
4247 return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
4249 EXPORT_SYMBOL(sleep_on_timeout);
4251 #ifdef CONFIG_RT_MUTEXES
4254 * rt_mutex_setprio - set the current priority of a task
4256 * @prio: prio value (kernel-internal form)
4258 * This function changes the 'effective' priority of a task. It does
4259 * not touch ->normal_prio like __setscheduler().
4261 * Used by the rt_mutex code to implement priority inheritance logic.
4263 void rt_mutex_setprio(struct task_struct *p, int prio)
4265 unsigned long flags;
4266 int oldprio, on_rq, running;
4268 const struct sched_class *prev_class = p->sched_class;
4270 BUG_ON(prio < 0 || prio > MAX_PRIO);
4272 rq = task_rq_lock(p, &flags);
4273 update_rq_clock(rq);
4276 on_rq = p->se.on_rq;
4277 running = task_current(rq, p);
4279 dequeue_task(rq, p, 0);
4281 p->sched_class->put_prev_task(rq, p);
4285 p->sched_class = &rt_sched_class;
4287 p->sched_class = &fair_sched_class;
4293 p->sched_class->set_curr_task(rq);
4295 enqueue_task(rq, p, 0);
4297 check_class_changed(rq, p, prev_class, oldprio, running);
4299 task_rq_unlock(rq, &flags);
4304 void set_user_nice(struct task_struct *p, long nice)
4306 int old_prio, delta, on_rq;
4307 unsigned long flags;
4310 if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
4313 * We have to be careful, if called from sys_setpriority(),
4314 * the task might be in the middle of scheduling on another CPU.
4316 rq = task_rq_lock(p, &flags);
4317 update_rq_clock(rq);
4319 * The RT priorities are set via sched_setscheduler(), but we still
4320 * allow the 'normal' nice value to be set - but as expected
4321 * it wont have any effect on scheduling until the task is
4322 * SCHED_FIFO/SCHED_RR:
4324 if (task_has_rt_policy(p)) {
4325 p->static_prio = NICE_TO_PRIO(nice);
4328 on_rq = p->se.on_rq;
4330 dequeue_task(rq, p, 0);
4332 p->static_prio = NICE_TO_PRIO(nice);
4335 p->prio = effective_prio(p);
4336 delta = p->prio - old_prio;
4339 enqueue_task(rq, p, 0);
4341 * If the task increased its priority or is running and
4342 * lowered its priority, then reschedule its CPU:
4344 if (delta < 0 || (delta > 0 && task_running(rq, p)))
4345 resched_task(rq->curr);
4348 task_rq_unlock(rq, &flags);
4350 EXPORT_SYMBOL(set_user_nice);
4353 * can_nice - check if a task can reduce its nice value
4357 int can_nice(const struct task_struct *p, const int nice)
4359 /* convert nice value [19,-20] to rlimit style value [1,40] */
4360 int nice_rlim = 20 - nice;
4362 return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
4363 capable(CAP_SYS_NICE));
4366 #ifdef __ARCH_WANT_SYS_NICE
4369 * sys_nice - change the priority of the current process.
4370 * @increment: priority increment
4372 * sys_setpriority is a more generic, but much slower function that
4373 * does similar things.
4375 asmlinkage long sys_nice(int increment)
4380 * Setpriority might change our priority at the same moment.
4381 * We don't have to worry. Conceptually one call occurs first
4382 * and we have a single winner.
4384 if (increment < -40)
4389 nice = PRIO_TO_NICE(current->static_prio) + increment;
4395 if (increment < 0 && !can_nice(current, nice))
4398 retval = security_task_setnice(current, nice);
4402 set_user_nice(current, nice);
4409 * task_prio - return the priority value of a given task.
4410 * @p: the task in question.
4412 * This is the priority value as seen by users in /proc.
4413 * RT tasks are offset by -200. Normal tasks are centered
4414 * around 0, value goes from -16 to +15.
4416 int task_prio(const struct task_struct *p)
4418 return p->prio - MAX_RT_PRIO;
4422 * task_nice - return the nice value of a given task.
4423 * @p: the task in question.
4425 int task_nice(const struct task_struct *p)
4427 return TASK_NICE(p);
4429 EXPORT_SYMBOL_GPL(task_nice);
4432 * idle_cpu - is a given cpu idle currently?
4433 * @cpu: the processor in question.
4435 int idle_cpu(int cpu)
4437 return cpu_curr(cpu) == cpu_rq(cpu)->idle;
4441 * idle_task - return the idle task for a given cpu.
4442 * @cpu: the processor in question.
4444 struct task_struct *idle_task(int cpu)
4446 return cpu_rq(cpu)->idle;
4450 * find_process_by_pid - find a process with a matching PID value.
4451 * @pid: the pid in question.
4453 static struct task_struct *find_process_by_pid(pid_t pid)
4455 return pid ? find_task_by_vpid(pid) : current;
4458 /* Actually do priority change: must hold rq lock. */
4460 __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
4462 BUG_ON(p->se.on_rq);
4465 switch (p->policy) {
4469 p->sched_class = &fair_sched_class;
4473 p->sched_class = &rt_sched_class;
4477 p->rt_priority = prio;
4478 p->normal_prio = normal_prio(p);
4479 /* we are holding p->pi_lock already */
4480 p->prio = rt_mutex_getprio(p);
4485 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4486 * @p: the task in question.
4487 * @policy: new policy.
4488 * @param: structure containing the new RT priority.
4490 * NOTE that the task may be already dead.
4492 int sched_setscheduler(struct task_struct *p, int policy,
4493 struct sched_param *param)
4495 int retval, oldprio, oldpolicy = -1, on_rq, running;
4496 unsigned long flags;
4497 const struct sched_class *prev_class = p->sched_class;
4500 /* may grab non-irq protected spin_locks */
4501 BUG_ON(in_interrupt());
4503 /* double check policy once rq lock held */
4505 policy = oldpolicy = p->policy;
4506 else if (policy != SCHED_FIFO && policy != SCHED_RR &&
4507 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
4508 policy != SCHED_IDLE)
4511 * Valid priorities for SCHED_FIFO and SCHED_RR are
4512 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4513 * SCHED_BATCH and SCHED_IDLE is 0.
4515 if (param->sched_priority < 0 ||
4516 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
4517 (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
4519 if (rt_policy(policy) != (param->sched_priority != 0))
4523 * Allow unprivileged RT tasks to decrease priority:
4525 if (!capable(CAP_SYS_NICE)) {
4526 if (rt_policy(policy)) {
4527 unsigned long rlim_rtprio;
4529 if (!lock_task_sighand(p, &flags))
4531 rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
4532 unlock_task_sighand(p, &flags);
4534 /* can't set/change the rt policy */
4535 if (policy != p->policy && !rlim_rtprio)
4538 /* can't increase priority */
4539 if (param->sched_priority > p->rt_priority &&
4540 param->sched_priority > rlim_rtprio)
4544 * Like positive nice levels, dont allow tasks to
4545 * move out of SCHED_IDLE either:
4547 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE)
4550 /* can't change other user's priorities */
4551 if ((current->euid != p->euid) &&
4552 (current->euid != p->uid))
4556 retval = security_task_setscheduler(p, policy, param);
4560 * make sure no PI-waiters arrive (or leave) while we are
4561 * changing the priority of the task:
4563 spin_lock_irqsave(&p->pi_lock, flags);
4565 * To be able to change p->policy safely, the apropriate
4566 * runqueue lock must be held.
4568 rq = __task_rq_lock(p);
4569 /* recheck policy now with rq lock held */
4570 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
4571 policy = oldpolicy = -1;
4572 __task_rq_unlock(rq);
4573 spin_unlock_irqrestore(&p->pi_lock, flags);
4576 update_rq_clock(rq);
4577 on_rq = p->se.on_rq;
4578 running = task_current(rq, p);
4580 deactivate_task(rq, p, 0);
4582 p->sched_class->put_prev_task(rq, p);
4586 __setscheduler(rq, p, policy, param->sched_priority);
4590 p->sched_class->set_curr_task(rq);
4592 activate_task(rq, p, 0);
4594 check_class_changed(rq, p, prev_class, oldprio, running);
4596 __task_rq_unlock(rq);
4597 spin_unlock_irqrestore(&p->pi_lock, flags);
4599 rt_mutex_adjust_pi(p);
4603 EXPORT_SYMBOL_GPL(sched_setscheduler);
4606 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4608 struct sched_param lparam;
4609 struct task_struct *p;
4612 if (!param || pid < 0)
4614 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4619 p = find_process_by_pid(pid);
4621 retval = sched_setscheduler(p, policy, &lparam);
4628 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4629 * @pid: the pid in question.
4630 * @policy: new policy.
4631 * @param: structure containing the new RT priority.
4634 sys_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4636 /* negative values for policy are not valid */
4640 return do_sched_setscheduler(pid, policy, param);
4644 * sys_sched_setparam - set/change the RT priority of a thread
4645 * @pid: the pid in question.
4646 * @param: structure containing the new RT priority.
4648 asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
4650 return do_sched_setscheduler(pid, -1, param);
4654 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4655 * @pid: the pid in question.
4657 asmlinkage long sys_sched_getscheduler(pid_t pid)
4659 struct task_struct *p;
4666 read_lock(&tasklist_lock);
4667 p = find_process_by_pid(pid);
4669 retval = security_task_getscheduler(p);
4673 read_unlock(&tasklist_lock);
4678 * sys_sched_getscheduler - get the RT priority of a thread
4679 * @pid: the pid in question.
4680 * @param: structure containing the RT priority.
4682 asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
4684 struct sched_param lp;
4685 struct task_struct *p;
4688 if (!param || pid < 0)
4691 read_lock(&tasklist_lock);
4692 p = find_process_by_pid(pid);
4697 retval = security_task_getscheduler(p);
4701 lp.sched_priority = p->rt_priority;
4702 read_unlock(&tasklist_lock);
4705 * This one might sleep, we cannot do it with a spinlock held ...
4707 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4712 read_unlock(&tasklist_lock);
4716 long sched_setaffinity(pid_t pid, cpumask_t new_mask)
4718 cpumask_t cpus_allowed;
4719 struct task_struct *p;
4723 read_lock(&tasklist_lock);
4725 p = find_process_by_pid(pid);
4727 read_unlock(&tasklist_lock);
4733 * It is not safe to call set_cpus_allowed with the
4734 * tasklist_lock held. We will bump the task_struct's
4735 * usage count and then drop tasklist_lock.
4738 read_unlock(&tasklist_lock);
4741 if ((current->euid != p->euid) && (current->euid != p->uid) &&
4742 !capable(CAP_SYS_NICE))
4745 retval = security_task_setscheduler(p, 0, NULL);
4749 cpus_allowed = cpuset_cpus_allowed(p);
4750 cpus_and(new_mask, new_mask, cpus_allowed);
4752 retval = set_cpus_allowed(p, new_mask);
4755 cpus_allowed = cpuset_cpus_allowed(p);
4756 if (!cpus_subset(new_mask, cpus_allowed)) {
4758 * We must have raced with a concurrent cpuset
4759 * update. Just reset the cpus_allowed to the
4760 * cpuset's cpus_allowed
4762 new_mask = cpus_allowed;
4772 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4773 cpumask_t *new_mask)
4775 if (len < sizeof(cpumask_t)) {
4776 memset(new_mask, 0, sizeof(cpumask_t));
4777 } else if (len > sizeof(cpumask_t)) {
4778 len = sizeof(cpumask_t);
4780 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4784 * sys_sched_setaffinity - set the cpu affinity of a process
4785 * @pid: pid of the process
4786 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4787 * @user_mask_ptr: user-space pointer to the new cpu mask
4789 asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
4790 unsigned long __user *user_mask_ptr)
4795 retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
4799 return sched_setaffinity(pid, new_mask);
4803 * Represents all cpu's present in the system
4804 * In systems capable of hotplug, this map could dynamically grow
4805 * as new cpu's are detected in the system via any platform specific
4806 * method, such as ACPI for e.g.
4809 cpumask_t cpu_present_map __read_mostly;
4810 EXPORT_SYMBOL(cpu_present_map);
4813 cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
4814 EXPORT_SYMBOL(cpu_online_map);
4816 cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
4817 EXPORT_SYMBOL(cpu_possible_map);
4820 long sched_getaffinity(pid_t pid, cpumask_t *mask)
4822 struct task_struct *p;
4826 read_lock(&tasklist_lock);
4829 p = find_process_by_pid(pid);
4833 retval = security_task_getscheduler(p);
4837 cpus_and(*mask, p->cpus_allowed, cpu_online_map);
4840 read_unlock(&tasklist_lock);
4847 * sys_sched_getaffinity - get the cpu affinity of a process
4848 * @pid: pid of the process
4849 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4850 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4852 asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
4853 unsigned long __user *user_mask_ptr)
4858 if (len < sizeof(cpumask_t))
4861 ret = sched_getaffinity(pid, &mask);
4865 if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
4868 return sizeof(cpumask_t);
4872 * sys_sched_yield - yield the current processor to other threads.
4874 * This function yields the current CPU to other tasks. If there are no
4875 * other threads running on this CPU then this function will return.
4877 asmlinkage long sys_sched_yield(void)
4879 struct rq *rq = this_rq_lock();
4881 schedstat_inc(rq, yld_count);
4882 current->sched_class->yield_task(rq);
4885 * Since we are going to call schedule() anyway, there's
4886 * no need to preempt or enable interrupts:
4888 __release(rq->lock);
4889 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4890 _raw_spin_unlock(&rq->lock);
4891 preempt_enable_no_resched();
4898 static void __cond_resched(void)
4900 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4901 __might_sleep(__FILE__, __LINE__);
4904 * The BKS might be reacquired before we have dropped
4905 * PREEMPT_ACTIVE, which could trigger a second
4906 * cond_resched() call.
4909 add_preempt_count(PREEMPT_ACTIVE);
4911 sub_preempt_count(PREEMPT_ACTIVE);
4912 } while (need_resched());
4915 #if !defined(CONFIG_PREEMPT) || defined(CONFIG_PREEMPT_VOLUNTARY)
4916 int __sched _cond_resched(void)
4918 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&
4919 system_state == SYSTEM_RUNNING) {
4925 EXPORT_SYMBOL(_cond_resched);
4929 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4930 * call schedule, and on return reacquire the lock.
4932 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4933 * operations here to prevent schedule() from being called twice (once via
4934 * spin_unlock(), once by hand).
4936 int cond_resched_lock(spinlock_t *lock)
4940 if (need_lockbreak(lock)) {
4946 if (need_resched() && system_state == SYSTEM_RUNNING) {
4947 spin_release(&lock->dep_map, 1, _THIS_IP_);
4948 _raw_spin_unlock(lock);
4949 preempt_enable_no_resched();
4956 EXPORT_SYMBOL(cond_resched_lock);
4958 int __sched cond_resched_softirq(void)
4960 BUG_ON(!in_softirq());
4962 if (need_resched() && system_state == SYSTEM_RUNNING) {
4970 EXPORT_SYMBOL(cond_resched_softirq);
4973 * yield - yield the current processor to other threads.
4975 * This is a shortcut for kernel-space yielding - it marks the
4976 * thread runnable and calls sys_sched_yield().
4978 void __sched yield(void)
4980 set_current_state(TASK_RUNNING);
4983 EXPORT_SYMBOL(yield);
4986 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4987 * that process accounting knows that this is a task in IO wait state.
4989 * But don't do that if it is a deliberate, throttling IO wait (this task
4990 * has set its backing_dev_info: the queue against which it should throttle)
4992 void __sched io_schedule(void)
4994 struct rq *rq = &__raw_get_cpu_var(runqueues);
4996 delayacct_blkio_start();
4997 atomic_inc(&rq->nr_iowait);
4999 atomic_dec(&rq->nr_iowait);
5000 delayacct_blkio_end();
5002 EXPORT_SYMBOL(io_schedule);
5004 long __sched io_schedule_timeout(long timeout)
5006 struct rq *rq = &__raw_get_cpu_var(runqueues);
5009 delayacct_blkio_start();
5010 atomic_inc(&rq->nr_iowait);
5011 ret = schedule_timeout(timeout);
5012 atomic_dec(&rq->nr_iowait);
5013 delayacct_blkio_end();
5018 * sys_sched_get_priority_max - return maximum RT priority.
5019 * @policy: scheduling class.
5021 * this syscall returns the maximum rt_priority that can be used
5022 * by a given scheduling class.
5024 asmlinkage long sys_sched_get_priority_max(int policy)
5031 ret = MAX_USER_RT_PRIO-1;
5043 * sys_sched_get_priority_min - return minimum RT priority.
5044 * @policy: scheduling class.
5046 * this syscall returns the minimum rt_priority that can be used
5047 * by a given scheduling class.
5049 asmlinkage long sys_sched_get_priority_min(int policy)
5067 * sys_sched_rr_get_interval - return the default timeslice of a process.
5068 * @pid: pid of the process.
5069 * @interval: userspace pointer to the timeslice value.
5071 * this syscall writes the default timeslice value of a given process
5072 * into the user-space timespec buffer. A value of '0' means infinity.
5075 long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
5077 struct task_struct *p;
5078 unsigned int time_slice;
5086 read_lock(&tasklist_lock);
5087 p = find_process_by_pid(pid);
5091 retval = security_task_getscheduler(p);
5096 * Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER
5097 * tasks that are on an otherwise idle runqueue:
5100 if (p->policy == SCHED_RR) {
5101 time_slice = DEF_TIMESLICE;
5103 struct sched_entity *se = &p->se;
5104 unsigned long flags;
5107 rq = task_rq_lock(p, &flags);
5108 if (rq->cfs.load.weight)
5109 time_slice = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
5110 task_rq_unlock(rq, &flags);
5112 read_unlock(&tasklist_lock);
5113 jiffies_to_timespec(time_slice, &t);
5114 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
5118 read_unlock(&tasklist_lock);
5122 static const char stat_nam[] = "RSDTtZX";
5124 void sched_show_task(struct task_struct *p)
5126 unsigned long free = 0;
5129 state = p->state ? __ffs(p->state) + 1 : 0;
5130 printk(KERN_INFO "%-13.13s %c", p->comm,
5131 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
5132 #if BITS_PER_LONG == 32
5133 if (state == TASK_RUNNING)
5134 printk(KERN_CONT " running ");
5136 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
5138 if (state == TASK_RUNNING)
5139 printk(KERN_CONT " running task ");
5141 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
5143 #ifdef CONFIG_DEBUG_STACK_USAGE
5145 unsigned long *n = end_of_stack(p);
5148 free = (unsigned long)n - (unsigned long)end_of_stack(p);
5151 printk(KERN_CONT "%5lu %5d %6d\n", free,
5152 task_pid_nr(p), task_pid_nr(p->real_parent));
5154 if (state != TASK_RUNNING)
5155 show_stack(p, NULL);
5158 void show_state_filter(unsigned long state_filter)
5160 struct task_struct *g, *p;
5162 #if BITS_PER_LONG == 32
5164 " task PC stack pid father\n");
5167 " task PC stack pid father\n");
5169 read_lock(&tasklist_lock);
5170 do_each_thread(g, p) {
5172 * reset the NMI-timeout, listing all files on a slow
5173 * console might take alot of time:
5175 touch_nmi_watchdog();
5176 if (!state_filter || (p->state & state_filter))
5178 } while_each_thread(g, p);
5180 touch_all_softlockup_watchdogs();
5182 #ifdef CONFIG_SCHED_DEBUG
5183 sysrq_sched_debug_show();
5185 read_unlock(&tasklist_lock);
5187 * Only show locks if all tasks are dumped:
5189 if (state_filter == -1)
5190 debug_show_all_locks();
5193 void __cpuinit init_idle_bootup_task(struct task_struct *idle)
5195 idle->sched_class = &idle_sched_class;
5199 * init_idle - set up an idle thread for a given CPU
5200 * @idle: task in question
5201 * @cpu: cpu the idle task belongs to
5203 * NOTE: this function does not set the idle thread's NEED_RESCHED
5204 * flag, to make booting more robust.
5206 void __cpuinit init_idle(struct task_struct *idle, int cpu)
5208 struct rq *rq = cpu_rq(cpu);
5209 unsigned long flags;
5212 idle->se.exec_start = sched_clock();
5214 idle->prio = idle->normal_prio = MAX_PRIO;
5215 idle->cpus_allowed = cpumask_of_cpu(cpu);
5216 __set_task_cpu(idle, cpu);
5218 spin_lock_irqsave(&rq->lock, flags);
5219 rq->curr = rq->idle = idle;
5220 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
5223 spin_unlock_irqrestore(&rq->lock, flags);
5225 /* Set the preempt count _outside_ the spinlocks! */
5226 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
5227 task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
5229 task_thread_info(idle)->preempt_count = 0;
5232 * The idle tasks have their own, simple scheduling class:
5234 idle->sched_class = &idle_sched_class;
5238 * In a system that switches off the HZ timer nohz_cpu_mask
5239 * indicates which cpus entered this state. This is used
5240 * in the rcu update to wait only for active cpus. For system
5241 * which do not switch off the HZ timer nohz_cpu_mask should
5242 * always be CPU_MASK_NONE.
5244 cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
5247 * Increase the granularity value when there are more CPUs,
5248 * because with more CPUs the 'effective latency' as visible
5249 * to users decreases. But the relationship is not linear,
5250 * so pick a second-best guess by going with the log2 of the
5253 * This idea comes from the SD scheduler of Con Kolivas:
5255 static inline void sched_init_granularity(void)
5257 unsigned int factor = 1 + ilog2(num_online_cpus());
5258 const unsigned long limit = 200000000;
5260 sysctl_sched_min_granularity *= factor;
5261 if (sysctl_sched_min_granularity > limit)
5262 sysctl_sched_min_granularity = limit;
5264 sysctl_sched_latency *= factor;
5265 if (sysctl_sched_latency > limit)
5266 sysctl_sched_latency = limit;
5268 sysctl_sched_wakeup_granularity *= factor;
5269 sysctl_sched_batch_wakeup_granularity *= factor;
5274 * This is how migration works:
5276 * 1) we queue a struct migration_req structure in the source CPU's
5277 * runqueue and wake up that CPU's migration thread.
5278 * 2) we down() the locked semaphore => thread blocks.
5279 * 3) migration thread wakes up (implicitly it forces the migrated
5280 * thread off the CPU)
5281 * 4) it gets the migration request and checks whether the migrated
5282 * task is still in the wrong runqueue.
5283 * 5) if it's in the wrong runqueue then the migration thread removes
5284 * it and puts it into the right queue.
5285 * 6) migration thread up()s the semaphore.
5286 * 7) we wake up and the migration is done.
5290 * Change a given task's CPU affinity. Migrate the thread to a
5291 * proper CPU and schedule it away if the CPU it's executing on
5292 * is removed from the allowed bitmask.
5294 * NOTE: the caller must have a valid reference to the task, the
5295 * task must not exit() & deallocate itself prematurely. The
5296 * call is not atomic; no spinlocks may be held.
5298 int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
5300 struct migration_req req;
5301 unsigned long flags;
5305 rq = task_rq_lock(p, &flags);
5306 if (!cpus_intersects(new_mask, cpu_online_map)) {
5311 if (p->sched_class->set_cpus_allowed)
5312 p->sched_class->set_cpus_allowed(p, &new_mask);
5314 p->cpus_allowed = new_mask;
5315 p->rt.nr_cpus_allowed = cpus_weight(new_mask);
5318 /* Can the task run on the task's current CPU? If so, we're done */
5319 if (cpu_isset(task_cpu(p), new_mask))
5322 if (migrate_task(p, any_online_cpu(new_mask), &req)) {
5323 /* Need help from migration thread: drop lock and wait. */
5324 task_rq_unlock(rq, &flags);
5325 wake_up_process(rq->migration_thread);
5326 wait_for_completion(&req.done);
5327 tlb_migrate_finish(p->mm);
5331 task_rq_unlock(rq, &flags);
5335 EXPORT_SYMBOL_GPL(set_cpus_allowed);
5338 * Move (not current) task off this cpu, onto dest cpu. We're doing
5339 * this because either it can't run here any more (set_cpus_allowed()
5340 * away from this CPU, or CPU going down), or because we're
5341 * attempting to rebalance this task on exec (sched_exec).
5343 * So we race with normal scheduler movements, but that's OK, as long
5344 * as the task is no longer on this CPU.
5346 * Returns non-zero if task was successfully migrated.
5348 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
5350 struct rq *rq_dest, *rq_src;
5353 if (unlikely(cpu_is_offline(dest_cpu)))
5356 rq_src = cpu_rq(src_cpu);
5357 rq_dest = cpu_rq(dest_cpu);
5359 double_rq_lock(rq_src, rq_dest);
5360 /* Already moved. */
5361 if (task_cpu(p) != src_cpu)
5363 /* Affinity changed (again). */
5364 if (!cpu_isset(dest_cpu, p->cpus_allowed))
5367 on_rq = p->se.on_rq;
5369 deactivate_task(rq_src, p, 0);
5371 set_task_cpu(p, dest_cpu);
5373 activate_task(rq_dest, p, 0);
5374 check_preempt_curr(rq_dest, p);
5378 double_rq_unlock(rq_src, rq_dest);
5383 * migration_thread - this is a highprio system thread that performs
5384 * thread migration by bumping thread off CPU then 'pushing' onto
5387 static int migration_thread(void *data)
5389 int cpu = (long)data;
5393 BUG_ON(rq->migration_thread != current);
5395 set_current_state(TASK_INTERRUPTIBLE);
5396 while (!kthread_should_stop()) {
5397 struct migration_req *req;
5398 struct list_head *head;
5400 spin_lock_irq(&rq->lock);
5402 if (cpu_is_offline(cpu)) {
5403 spin_unlock_irq(&rq->lock);
5407 if (rq->active_balance) {
5408 active_load_balance(rq, cpu);
5409 rq->active_balance = 0;
5412 head = &rq->migration_queue;
5414 if (list_empty(head)) {
5415 spin_unlock_irq(&rq->lock);
5417 set_current_state(TASK_INTERRUPTIBLE);
5420 req = list_entry(head->next, struct migration_req, list);
5421 list_del_init(head->next);
5423 spin_unlock(&rq->lock);
5424 __migrate_task(req->task, cpu, req->dest_cpu);
5427 complete(&req->done);
5429 __set_current_state(TASK_RUNNING);
5433 /* Wait for kthread_stop */
5434 set_current_state(TASK_INTERRUPTIBLE);
5435 while (!kthread_should_stop()) {
5437 set_current_state(TASK_INTERRUPTIBLE);
5439 __set_current_state(TASK_RUNNING);
5443 #ifdef CONFIG_HOTPLUG_CPU
5445 static int __migrate_task_irq(struct task_struct *p, int src_cpu, int dest_cpu)
5449 local_irq_disable();
5450 ret = __migrate_task(p, src_cpu, dest_cpu);
5456 * Figure out where task on dead CPU should go, use force if necessary.
5457 * NOTE: interrupts should be disabled by the caller
5459 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
5461 unsigned long flags;
5468 mask = node_to_cpumask(cpu_to_node(dead_cpu));
5469 cpus_and(mask, mask, p->cpus_allowed);
5470 dest_cpu = any_online_cpu(mask);
5472 /* On any allowed CPU? */
5473 if (dest_cpu == NR_CPUS)
5474 dest_cpu = any_online_cpu(p->cpus_allowed);
5476 /* No more Mr. Nice Guy. */
5477 if (dest_cpu == NR_CPUS) {
5478 cpumask_t cpus_allowed = cpuset_cpus_allowed_locked(p);
5480 * Try to stay on the same cpuset, where the
5481 * current cpuset may be a subset of all cpus.
5482 * The cpuset_cpus_allowed_locked() variant of
5483 * cpuset_cpus_allowed() will not block. It must be
5484 * called within calls to cpuset_lock/cpuset_unlock.
5486 rq = task_rq_lock(p, &flags);
5487 p->cpus_allowed = cpus_allowed;
5488 dest_cpu = any_online_cpu(p->cpus_allowed);
5489 task_rq_unlock(rq, &flags);
5492 * Don't tell them about moving exiting tasks or
5493 * kernel threads (both mm NULL), since they never
5496 if (p->mm && printk_ratelimit()) {
5497 printk(KERN_INFO "process %d (%s) no "
5498 "longer affine to cpu%d\n",
5499 task_pid_nr(p), p->comm, dead_cpu);
5502 } while (!__migrate_task_irq(p, dead_cpu, dest_cpu));
5506 * While a dead CPU has no uninterruptible tasks queued at this point,
5507 * it might still have a nonzero ->nr_uninterruptible counter, because
5508 * for performance reasons the counter is not stricly tracking tasks to
5509 * their home CPUs. So we just add the counter to another CPU's counter,
5510 * to keep the global sum constant after CPU-down:
5512 static void migrate_nr_uninterruptible(struct rq *rq_src)
5514 struct rq *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL));
5515 unsigned long flags;
5517 local_irq_save(flags);
5518 double_rq_lock(rq_src, rq_dest);
5519 rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
5520 rq_src->nr_uninterruptible = 0;
5521 double_rq_unlock(rq_src, rq_dest);
5522 local_irq_restore(flags);
5525 /* Run through task list and migrate tasks from the dead cpu. */
5526 static void migrate_live_tasks(int src_cpu)
5528 struct task_struct *p, *t;
5530 read_lock(&tasklist_lock);
5532 do_each_thread(t, p) {
5536 if (task_cpu(p) == src_cpu)
5537 move_task_off_dead_cpu(src_cpu, p);
5538 } while_each_thread(t, p);
5540 read_unlock(&tasklist_lock);
5544 * Schedules idle task to be the next runnable task on current CPU.
5545 * It does so by boosting its priority to highest possible.
5546 * Used by CPU offline code.
5548 void sched_idle_next(void)
5550 int this_cpu = smp_processor_id();
5551 struct rq *rq = cpu_rq(this_cpu);
5552 struct task_struct *p = rq->idle;
5553 unsigned long flags;
5555 /* cpu has to be offline */
5556 BUG_ON(cpu_online(this_cpu));
5559 * Strictly not necessary since rest of the CPUs are stopped by now
5560 * and interrupts disabled on the current cpu.
5562 spin_lock_irqsave(&rq->lock, flags);
5564 __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
5566 update_rq_clock(rq);
5567 activate_task(rq, p, 0);
5569 spin_unlock_irqrestore(&rq->lock, flags);
5573 * Ensures that the idle task is using init_mm right before its cpu goes
5576 void idle_task_exit(void)
5578 struct mm_struct *mm = current->active_mm;
5580 BUG_ON(cpu_online(smp_processor_id()));
5583 switch_mm(mm, &init_mm, current);
5587 /* called under rq->lock with disabled interrupts */
5588 static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
5590 struct rq *rq = cpu_rq(dead_cpu);
5592 /* Must be exiting, otherwise would be on tasklist. */
5593 BUG_ON(!p->exit_state);
5595 /* Cannot have done final schedule yet: would have vanished. */
5596 BUG_ON(p->state == TASK_DEAD);
5601 * Drop lock around migration; if someone else moves it,
5602 * that's OK. No task can be added to this CPU, so iteration is
5605 spin_unlock_irq(&rq->lock);
5606 move_task_off_dead_cpu(dead_cpu, p);
5607 spin_lock_irq(&rq->lock);
5612 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5613 static void migrate_dead_tasks(unsigned int dead_cpu)
5615 struct rq *rq = cpu_rq(dead_cpu);
5616 struct task_struct *next;
5619 if (!rq->nr_running)
5621 update_rq_clock(rq);
5622 next = pick_next_task(rq, rq->curr);
5625 migrate_dead(dead_cpu, next);
5629 #endif /* CONFIG_HOTPLUG_CPU */
5631 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5633 static struct ctl_table sd_ctl_dir[] = {
5635 .procname = "sched_domain",
5641 static struct ctl_table sd_ctl_root[] = {
5643 .ctl_name = CTL_KERN,
5644 .procname = "kernel",
5646 .child = sd_ctl_dir,
5651 static struct ctl_table *sd_alloc_ctl_entry(int n)
5653 struct ctl_table *entry =
5654 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
5659 static void sd_free_ctl_entry(struct ctl_table **tablep)
5661 struct ctl_table *entry;
5664 * In the intermediate directories, both the child directory and
5665 * procname are dynamically allocated and could fail but the mode
5666 * will always be set. In the lowest directory the names are
5667 * static strings and all have proc handlers.
5669 for (entry = *tablep; entry->mode; entry++) {
5671 sd_free_ctl_entry(&entry->child);
5672 if (entry->proc_handler == NULL)
5673 kfree(entry->procname);
5681 set_table_entry(struct ctl_table *entry,
5682 const char *procname, void *data, int maxlen,
5683 mode_t mode, proc_handler *proc_handler)
5685 entry->procname = procname;
5687 entry->maxlen = maxlen;
5689 entry->proc_handler = proc_handler;
5692 static struct ctl_table *
5693 sd_alloc_ctl_domain_table(struct sched_domain *sd)
5695 struct ctl_table *table = sd_alloc_ctl_entry(12);
5700 set_table_entry(&table[0], "min_interval", &sd->min_interval,
5701 sizeof(long), 0644, proc_doulongvec_minmax);
5702 set_table_entry(&table[1], "max_interval", &sd->max_interval,
5703 sizeof(long), 0644, proc_doulongvec_minmax);
5704 set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
5705 sizeof(int), 0644, proc_dointvec_minmax);
5706 set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
5707 sizeof(int), 0644, proc_dointvec_minmax);
5708 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
5709 sizeof(int), 0644, proc_dointvec_minmax);
5710 set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
5711 sizeof(int), 0644, proc_dointvec_minmax);
5712 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
5713 sizeof(int), 0644, proc_dointvec_minmax);
5714 set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
5715 sizeof(int), 0644, proc_dointvec_minmax);
5716 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
5717 sizeof(int), 0644, proc_dointvec_minmax);
5718 set_table_entry(&table[9], "cache_nice_tries",
5719 &sd->cache_nice_tries,
5720 sizeof(int), 0644, proc_dointvec_minmax);
5721 set_table_entry(&table[10], "flags", &sd->flags,
5722 sizeof(int), 0644, proc_dointvec_minmax);
5723 /* &table[11] is terminator */
5728 static ctl_table *sd_alloc_ctl_cpu_table(int cpu)
5730 struct ctl_table *entry, *table;
5731 struct sched_domain *sd;
5732 int domain_num = 0, i;
5735 for_each_domain(cpu, sd)
5737 entry = table = sd_alloc_ctl_entry(domain_num + 1);
5742 for_each_domain(cpu, sd) {
5743 snprintf(buf, 32, "domain%d", i);
5744 entry->procname = kstrdup(buf, GFP_KERNEL);
5746 entry->child = sd_alloc_ctl_domain_table(sd);
5753 static struct ctl_table_header *sd_sysctl_header;
5754 static void register_sched_domain_sysctl(void)
5756 int i, cpu_num = num_online_cpus();
5757 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
5760 WARN_ON(sd_ctl_dir[0].child);
5761 sd_ctl_dir[0].child = entry;
5766 for_each_online_cpu(i) {
5767 snprintf(buf, 32, "cpu%d", i);
5768 entry->procname = kstrdup(buf, GFP_KERNEL);
5770 entry->child = sd_alloc_ctl_cpu_table(i);
5774 WARN_ON(sd_sysctl_header);
5775 sd_sysctl_header = register_sysctl_table(sd_ctl_root);
5778 /* may be called multiple times per register */
5779 static void unregister_sched_domain_sysctl(void)
5781 if (sd_sysctl_header)
5782 unregister_sysctl_table(sd_sysctl_header);
5783 sd_sysctl_header = NULL;
5784 if (sd_ctl_dir[0].child)
5785 sd_free_ctl_entry(&sd_ctl_dir[0].child);
5788 static void register_sched_domain_sysctl(void)
5791 static void unregister_sched_domain_sysctl(void)
5797 * migration_call - callback that gets triggered when a CPU is added.
5798 * Here we can start up the necessary migration thread for the new CPU.
5800 static int __cpuinit
5801 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5803 struct task_struct *p;
5804 int cpu = (long)hcpu;
5805 unsigned long flags;
5810 case CPU_UP_PREPARE:
5811 case CPU_UP_PREPARE_FROZEN:
5812 p = kthread_create(migration_thread, hcpu, "migration/%d", cpu);
5815 kthread_bind(p, cpu);
5816 /* Must be high prio: stop_machine expects to yield to it. */
5817 rq = task_rq_lock(p, &flags);
5818 __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
5819 task_rq_unlock(rq, &flags);
5820 cpu_rq(cpu)->migration_thread = p;
5824 case CPU_ONLINE_FROZEN:
5825 /* Strictly unnecessary, as first user will wake it. */
5826 wake_up_process(cpu_rq(cpu)->migration_thread);
5828 /* Update our root-domain */
5830 spin_lock_irqsave(&rq->lock, flags);
5832 BUG_ON(!cpu_isset(cpu, rq->rd->span));
5833 cpu_set(cpu, rq->rd->online);
5835 spin_unlock_irqrestore(&rq->lock, flags);
5838 #ifdef CONFIG_HOTPLUG_CPU
5839 case CPU_UP_CANCELED:
5840 case CPU_UP_CANCELED_FROZEN:
5841 if (!cpu_rq(cpu)->migration_thread)
5843 /* Unbind it from offline cpu so it can run. Fall thru. */
5844 kthread_bind(cpu_rq(cpu)->migration_thread,
5845 any_online_cpu(cpu_online_map));
5846 kthread_stop(cpu_rq(cpu)->migration_thread);
5847 cpu_rq(cpu)->migration_thread = NULL;
5851 case CPU_DEAD_FROZEN:
5852 cpuset_lock(); /* around calls to cpuset_cpus_allowed_lock() */
5853 migrate_live_tasks(cpu);
5855 kthread_stop(rq->migration_thread);
5856 rq->migration_thread = NULL;
5857 /* Idle task back to normal (off runqueue, low prio) */
5858 spin_lock_irq(&rq->lock);
5859 update_rq_clock(rq);
5860 deactivate_task(rq, rq->idle, 0);
5861 rq->idle->static_prio = MAX_PRIO;
5862 __setscheduler(rq, rq->idle, SCHED_NORMAL, 0);
5863 rq->idle->sched_class = &idle_sched_class;
5864 migrate_dead_tasks(cpu);
5865 spin_unlock_irq(&rq->lock);
5867 migrate_nr_uninterruptible(rq);
5868 BUG_ON(rq->nr_running != 0);
5871 * No need to migrate the tasks: it was best-effort if
5872 * they didn't take sched_hotcpu_mutex. Just wake up
5875 spin_lock_irq(&rq->lock);
5876 while (!list_empty(&rq->migration_queue)) {
5877 struct migration_req *req;
5879 req = list_entry(rq->migration_queue.next,
5880 struct migration_req, list);
5881 list_del_init(&req->list);
5882 complete(&req->done);
5884 spin_unlock_irq(&rq->lock);
5887 case CPU_DOWN_PREPARE:
5888 /* Update our root-domain */
5890 spin_lock_irqsave(&rq->lock, flags);
5892 BUG_ON(!cpu_isset(cpu, rq->rd->span));
5893 cpu_clear(cpu, rq->rd->online);
5895 spin_unlock_irqrestore(&rq->lock, flags);
5902 /* Register at highest priority so that task migration (migrate_all_tasks)
5903 * happens before everything else.
5905 static struct notifier_block __cpuinitdata migration_notifier = {
5906 .notifier_call = migration_call,
5910 void __init migration_init(void)
5912 void *cpu = (void *)(long)smp_processor_id();
5915 /* Start one for the boot CPU: */
5916 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5917 BUG_ON(err == NOTIFY_BAD);
5918 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5919 register_cpu_notifier(&migration_notifier);
5925 /* Number of possible processor ids */
5926 int nr_cpu_ids __read_mostly = NR_CPUS;
5927 EXPORT_SYMBOL(nr_cpu_ids);
5929 #ifdef CONFIG_SCHED_DEBUG
5931 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level)
5933 struct sched_group *group = sd->groups;
5934 cpumask_t groupmask;
5937 cpumask_scnprintf(str, NR_CPUS, sd->span);
5938 cpus_clear(groupmask);
5940 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5942 if (!(sd->flags & SD_LOAD_BALANCE)) {
5943 printk("does not load-balance\n");
5945 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5950 printk(KERN_CONT "span %s\n", str);
5952 if (!cpu_isset(cpu, sd->span)) {
5953 printk(KERN_ERR "ERROR: domain->span does not contain "
5956 if (!cpu_isset(cpu, group->cpumask)) {
5957 printk(KERN_ERR "ERROR: domain->groups does not contain"
5961 printk(KERN_DEBUG "%*s groups:", level + 1, "");
5965 printk(KERN_ERR "ERROR: group is NULL\n");
5969 if (!group->__cpu_power) {
5970 printk(KERN_CONT "\n");
5971 printk(KERN_ERR "ERROR: domain->cpu_power not "
5976 if (!cpus_weight(group->cpumask)) {
5977 printk(KERN_CONT "\n");
5978 printk(KERN_ERR "ERROR: empty group\n");
5982 if (cpus_intersects(groupmask, group->cpumask)) {
5983 printk(KERN_CONT "\n");
5984 printk(KERN_ERR "ERROR: repeated CPUs\n");
5988 cpus_or(groupmask, groupmask, group->cpumask);
5990 cpumask_scnprintf(str, NR_CPUS, group->cpumask);
5991 printk(KERN_CONT " %s", str);
5993 group = group->next;
5994 } while (group != sd->groups);
5995 printk(KERN_CONT "\n");
5997 if (!cpus_equal(sd->span, groupmask))
5998 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
6000 if (sd->parent && !cpus_subset(groupmask, sd->parent->span))
6001 printk(KERN_ERR "ERROR: parent span is not a superset "
6002 "of domain->span\n");
6006 static void sched_domain_debug(struct sched_domain *sd, int cpu)
6011 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
6015 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
6018 if (sched_domain_debug_one(sd, cpu, level))
6027 # define sched_domain_debug(sd, cpu) do { } while (0)
6030 static int sd_degenerate(struct sched_domain *sd)
6032 if (cpus_weight(sd->span) == 1)
6035 /* Following flags need at least 2 groups */
6036 if (sd->flags & (SD_LOAD_BALANCE |
6037 SD_BALANCE_NEWIDLE |
6041 SD_SHARE_PKG_RESOURCES)) {
6042 if (sd->groups != sd->groups->next)
6046 /* Following flags don't use groups */
6047 if (sd->flags & (SD_WAKE_IDLE |
6056 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
6058 unsigned long cflags = sd->flags, pflags = parent->flags;
6060 if (sd_degenerate(parent))
6063 if (!cpus_equal(sd->span, parent->span))
6066 /* Does parent contain flags not in child? */
6067 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
6068 if (cflags & SD_WAKE_AFFINE)
6069 pflags &= ~SD_WAKE_BALANCE;
6070 /* Flags needing groups don't count if only 1 group in parent */
6071 if (parent->groups == parent->groups->next) {
6072 pflags &= ~(SD_LOAD_BALANCE |
6073 SD_BALANCE_NEWIDLE |
6077 SD_SHARE_PKG_RESOURCES);
6079 if (~cflags & pflags)
6085 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
6087 unsigned long flags;
6088 const struct sched_class *class;
6090 spin_lock_irqsave(&rq->lock, flags);
6093 struct root_domain *old_rd = rq->rd;
6095 for (class = sched_class_highest; class; class = class->next) {
6096 if (class->leave_domain)
6097 class->leave_domain(rq);
6100 cpu_clear(rq->cpu, old_rd->span);
6101 cpu_clear(rq->cpu, old_rd->online);
6103 if (atomic_dec_and_test(&old_rd->refcount))
6107 atomic_inc(&rd->refcount);
6110 cpu_set(rq->cpu, rd->span);
6111 if (cpu_isset(rq->cpu, cpu_online_map))
6112 cpu_set(rq->cpu, rd->online);
6114 for (class = sched_class_highest; class; class = class->next) {
6115 if (class->join_domain)
6116 class->join_domain(rq);
6119 spin_unlock_irqrestore(&rq->lock, flags);
6122 static void init_rootdomain(struct root_domain *rd)
6124 memset(rd, 0, sizeof(*rd));
6126 cpus_clear(rd->span);
6127 cpus_clear(rd->online);
6130 static void init_defrootdomain(void)
6132 init_rootdomain(&def_root_domain);
6133 atomic_set(&def_root_domain.refcount, 1);
6136 static struct root_domain *alloc_rootdomain(void)
6138 struct root_domain *rd;
6140 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
6144 init_rootdomain(rd);
6150 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
6151 * hold the hotplug lock.
6154 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
6156 struct rq *rq = cpu_rq(cpu);
6157 struct sched_domain *tmp;
6159 /* Remove the sched domains which do not contribute to scheduling. */
6160 for (tmp = sd; tmp; tmp = tmp->parent) {
6161 struct sched_domain *parent = tmp->parent;
6164 if (sd_parent_degenerate(tmp, parent)) {
6165 tmp->parent = parent->parent;
6167 parent->parent->child = tmp;
6171 if (sd && sd_degenerate(sd)) {
6177 sched_domain_debug(sd, cpu);
6179 rq_attach_root(rq, rd);
6180 rcu_assign_pointer(rq->sd, sd);
6183 /* cpus with isolated domains */
6184 static cpumask_t cpu_isolated_map = CPU_MASK_NONE;
6186 /* Setup the mask of cpus configured for isolated domains */
6187 static int __init isolated_cpu_setup(char *str)
6189 int ints[NR_CPUS], i;
6191 str = get_options(str, ARRAY_SIZE(ints), ints);
6192 cpus_clear(cpu_isolated_map);
6193 for (i = 1; i <= ints[0]; i++)
6194 if (ints[i] < NR_CPUS)
6195 cpu_set(ints[i], cpu_isolated_map);
6199 __setup("isolcpus=", isolated_cpu_setup);
6202 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
6203 * to a function which identifies what group(along with sched group) a CPU
6204 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
6205 * (due to the fact that we keep track of groups covered with a cpumask_t).
6207 * init_sched_build_groups will build a circular linked list of the groups
6208 * covered by the given span, and will set each group's ->cpumask correctly,
6209 * and ->cpu_power to 0.
6212 init_sched_build_groups(cpumask_t span, const cpumask_t *cpu_map,
6213 int (*group_fn)(int cpu, const cpumask_t *cpu_map,
6214 struct sched_group **sg))
6216 struct sched_group *first = NULL, *last = NULL;
6217 cpumask_t covered = CPU_MASK_NONE;
6220 for_each_cpu_mask(i, span) {
6221 struct sched_group *sg;
6222 int group = group_fn(i, cpu_map, &sg);
6225 if (cpu_isset(i, covered))
6228 sg->cpumask = CPU_MASK_NONE;
6229 sg->__cpu_power = 0;
6231 for_each_cpu_mask(j, span) {
6232 if (group_fn(j, cpu_map, NULL) != group)
6235 cpu_set(j, covered);
6236 cpu_set(j, sg->cpumask);
6247 #define SD_NODES_PER_DOMAIN 16
6252 * find_next_best_node - find the next node to include in a sched_domain
6253 * @node: node whose sched_domain we're building
6254 * @used_nodes: nodes already in the sched_domain
6256 * Find the next node to include in a given scheduling domain. Simply
6257 * finds the closest node not already in the @used_nodes map.
6259 * Should use nodemask_t.
6261 static int find_next_best_node(int node, unsigned long *used_nodes)
6263 int i, n, val, min_val, best_node = 0;
6267 for (i = 0; i < MAX_NUMNODES; i++) {
6268 /* Start at @node */
6269 n = (node + i) % MAX_NUMNODES;
6271 if (!nr_cpus_node(n))
6274 /* Skip already used nodes */
6275 if (test_bit(n, used_nodes))
6278 /* Simple min distance search */
6279 val = node_distance(node, n);
6281 if (val < min_val) {
6287 set_bit(best_node, used_nodes);
6292 * sched_domain_node_span - get a cpumask for a node's sched_domain
6293 * @node: node whose cpumask we're constructing
6294 * @size: number of nodes to include in this span
6296 * Given a node, construct a good cpumask for its sched_domain to span. It
6297 * should be one that prevents unnecessary balancing, but also spreads tasks
6300 static cpumask_t sched_domain_node_span(int node)
6302 DECLARE_BITMAP(used_nodes, MAX_NUMNODES);
6303 cpumask_t span, nodemask;
6307 bitmap_zero(used_nodes, MAX_NUMNODES);
6309 nodemask = node_to_cpumask(node);
6310 cpus_or(span, span, nodemask);
6311 set_bit(node, used_nodes);
6313 for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
6314 int next_node = find_next_best_node(node, used_nodes);
6316 nodemask = node_to_cpumask(next_node);
6317 cpus_or(span, span, nodemask);
6324 int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
6327 * SMT sched-domains:
6329 #ifdef CONFIG_SCHED_SMT
6330 static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
6331 static DEFINE_PER_CPU(struct sched_group, sched_group_cpus);
6334 cpu_to_cpu_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg)
6337 *sg = &per_cpu(sched_group_cpus, cpu);
6343 * multi-core sched-domains:
6345 #ifdef CONFIG_SCHED_MC
6346 static DEFINE_PER_CPU(struct sched_domain, core_domains);
6347 static DEFINE_PER_CPU(struct sched_group, sched_group_core);
6350 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6352 cpu_to_core_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg)
6355 cpumask_t mask = per_cpu(cpu_sibling_map, cpu);
6356 cpus_and(mask, mask, *cpu_map);
6357 group = first_cpu(mask);
6359 *sg = &per_cpu(sched_group_core, group);
6362 #elif defined(CONFIG_SCHED_MC)
6364 cpu_to_core_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg)
6367 *sg = &per_cpu(sched_group_core, cpu);
6372 static DEFINE_PER_CPU(struct sched_domain, phys_domains);
6373 static DEFINE_PER_CPU(struct sched_group, sched_group_phys);
6376 cpu_to_phys_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg)
6379 #ifdef CONFIG_SCHED_MC
6380 cpumask_t mask = cpu_coregroup_map(cpu);
6381 cpus_and(mask, mask, *cpu_map);
6382 group = first_cpu(mask);
6383 #elif defined(CONFIG_SCHED_SMT)
6384 cpumask_t mask = per_cpu(cpu_sibling_map, cpu);
6385 cpus_and(mask, mask, *cpu_map);
6386 group = first_cpu(mask);
6391 *sg = &per_cpu(sched_group_phys, group);
6397 * The init_sched_build_groups can't handle what we want to do with node
6398 * groups, so roll our own. Now each node has its own list of groups which
6399 * gets dynamically allocated.
6401 static DEFINE_PER_CPU(struct sched_domain, node_domains);
6402 static struct sched_group **sched_group_nodes_bycpu[NR_CPUS];
6404 static DEFINE_PER_CPU(struct sched_domain, allnodes_domains);
6405 static DEFINE_PER_CPU(struct sched_group, sched_group_allnodes);
6407 static int cpu_to_allnodes_group(int cpu, const cpumask_t *cpu_map,
6408 struct sched_group **sg)
6410 cpumask_t nodemask = node_to_cpumask(cpu_to_node(cpu));
6413 cpus_and(nodemask, nodemask, *cpu_map);
6414 group = first_cpu(nodemask);
6417 *sg = &per_cpu(sched_group_allnodes, group);
6421 static void init_numa_sched_groups_power(struct sched_group *group_head)
6423 struct sched_group *sg = group_head;
6429 for_each_cpu_mask(j, sg->cpumask) {
6430 struct sched_domain *sd;
6432 sd = &per_cpu(phys_domains, j);
6433 if (j != first_cpu(sd->groups->cpumask)) {
6435 * Only add "power" once for each
6441 sg_inc_cpu_power(sg, sd->groups->__cpu_power);
6444 } while (sg != group_head);
6449 /* Free memory allocated for various sched_group structures */
6450 static void free_sched_groups(const cpumask_t *cpu_map)
6454 for_each_cpu_mask(cpu, *cpu_map) {
6455 struct sched_group **sched_group_nodes
6456 = sched_group_nodes_bycpu[cpu];
6458 if (!sched_group_nodes)
6461 for (i = 0; i < MAX_NUMNODES; i++) {
6462 cpumask_t nodemask = node_to_cpumask(i);
6463 struct sched_group *oldsg, *sg = sched_group_nodes[i];
6465 cpus_and(nodemask, nodemask, *cpu_map);
6466 if (cpus_empty(nodemask))
6476 if (oldsg != sched_group_nodes[i])
6479 kfree(sched_group_nodes);
6480 sched_group_nodes_bycpu[cpu] = NULL;
6484 static void free_sched_groups(const cpumask_t *cpu_map)
6490 * Initialize sched groups cpu_power.
6492 * cpu_power indicates the capacity of sched group, which is used while
6493 * distributing the load between different sched groups in a sched domain.
6494 * Typically cpu_power for all the groups in a sched domain will be same unless
6495 * there are asymmetries in the topology. If there are asymmetries, group
6496 * having more cpu_power will pickup more load compared to the group having
6499 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
6500 * the maximum number of tasks a group can handle in the presence of other idle
6501 * or lightly loaded groups in the same sched domain.
6503 static void init_sched_groups_power(int cpu, struct sched_domain *sd)
6505 struct sched_domain *child;
6506 struct sched_group *group;
6508 WARN_ON(!sd || !sd->groups);
6510 if (cpu != first_cpu(sd->groups->cpumask))
6515 sd->groups->__cpu_power = 0;
6518 * For perf policy, if the groups in child domain share resources
6519 * (for example cores sharing some portions of the cache hierarchy
6520 * or SMT), then set this domain groups cpu_power such that each group
6521 * can handle only one task, when there are other idle groups in the
6522 * same sched domain.
6524 if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) &&
6526 (SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) {
6527 sg_inc_cpu_power(sd->groups, SCHED_LOAD_SCALE);
6532 * add cpu_power of each child group to this groups cpu_power
6534 group = child->groups;
6536 sg_inc_cpu_power(sd->groups, group->__cpu_power);
6537 group = group->next;
6538 } while (group != child->groups);
6542 * Build sched domains for a given set of cpus and attach the sched domains
6543 * to the individual cpus
6545 static int build_sched_domains(const cpumask_t *cpu_map)
6548 struct root_domain *rd;
6550 struct sched_group **sched_group_nodes = NULL;
6551 int sd_allnodes = 0;
6554 * Allocate the per-node list of sched groups
6556 sched_group_nodes = kcalloc(MAX_NUMNODES, sizeof(struct sched_group *),
6558 if (!sched_group_nodes) {
6559 printk(KERN_WARNING "Can not alloc sched group node list\n");
6562 sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes;
6565 rd = alloc_rootdomain();
6567 printk(KERN_WARNING "Cannot alloc root domain\n");
6572 * Set up domains for cpus specified by the cpu_map.
6574 for_each_cpu_mask(i, *cpu_map) {
6575 struct sched_domain *sd = NULL, *p;
6576 cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
6578 cpus_and(nodemask, nodemask, *cpu_map);
6581 if (cpus_weight(*cpu_map) >
6582 SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) {
6583 sd = &per_cpu(allnodes_domains, i);
6584 *sd = SD_ALLNODES_INIT;
6585 sd->span = *cpu_map;
6586 cpu_to_allnodes_group(i, cpu_map, &sd->groups);
6592 sd = &per_cpu(node_domains, i);
6594 sd->span = sched_domain_node_span(cpu_to_node(i));
6598 cpus_and(sd->span, sd->span, *cpu_map);
6602 sd = &per_cpu(phys_domains, i);
6604 sd->span = nodemask;
6608 cpu_to_phys_group(i, cpu_map, &sd->groups);
6610 #ifdef CONFIG_SCHED_MC
6612 sd = &per_cpu(core_domains, i);
6614 sd->span = cpu_coregroup_map(i);
6615 cpus_and(sd->span, sd->span, *cpu_map);
6618 cpu_to_core_group(i, cpu_map, &sd->groups);
6621 #ifdef CONFIG_SCHED_SMT
6623 sd = &per_cpu(cpu_domains, i);
6624 *sd = SD_SIBLING_INIT;
6625 sd->span = per_cpu(cpu_sibling_map, i);
6626 cpus_and(sd->span, sd->span, *cpu_map);
6629 cpu_to_cpu_group(i, cpu_map, &sd->groups);
6633 #ifdef CONFIG_SCHED_SMT
6634 /* Set up CPU (sibling) groups */
6635 for_each_cpu_mask(i, *cpu_map) {
6636 cpumask_t this_sibling_map = per_cpu(cpu_sibling_map, i);
6637 cpus_and(this_sibling_map, this_sibling_map, *cpu_map);
6638 if (i != first_cpu(this_sibling_map))
6641 init_sched_build_groups(this_sibling_map, cpu_map,
6646 #ifdef CONFIG_SCHED_MC
6647 /* Set up multi-core groups */
6648 for_each_cpu_mask(i, *cpu_map) {
6649 cpumask_t this_core_map = cpu_coregroup_map(i);
6650 cpus_and(this_core_map, this_core_map, *cpu_map);
6651 if (i != first_cpu(this_core_map))
6653 init_sched_build_groups(this_core_map, cpu_map,
6654 &cpu_to_core_group);
6658 /* Set up physical groups */
6659 for (i = 0; i < MAX_NUMNODES; i++) {
6660 cpumask_t nodemask = node_to_cpumask(i);
6662 cpus_and(nodemask, nodemask, *cpu_map);
6663 if (cpus_empty(nodemask))
6666 init_sched_build_groups(nodemask, cpu_map, &cpu_to_phys_group);
6670 /* Set up node groups */
6672 init_sched_build_groups(*cpu_map, cpu_map,
6673 &cpu_to_allnodes_group);
6675 for (i = 0; i < MAX_NUMNODES; i++) {
6676 /* Set up node groups */
6677 struct sched_group *sg, *prev;
6678 cpumask_t nodemask = node_to_cpumask(i);
6679 cpumask_t domainspan;
6680 cpumask_t covered = CPU_MASK_NONE;
6683 cpus_and(nodemask, nodemask, *cpu_map);
6684 if (cpus_empty(nodemask)) {
6685 sched_group_nodes[i] = NULL;
6689 domainspan = sched_domain_node_span(i);
6690 cpus_and(domainspan, domainspan, *cpu_map);
6692 sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i);
6694 printk(KERN_WARNING "Can not alloc domain group for "
6698 sched_group_nodes[i] = sg;
6699 for_each_cpu_mask(j, nodemask) {
6700 struct sched_domain *sd;
6702 sd = &per_cpu(node_domains, j);
6705 sg->__cpu_power = 0;
6706 sg->cpumask = nodemask;
6708 cpus_or(covered, covered, nodemask);
6711 for (j = 0; j < MAX_NUMNODES; j++) {
6712 cpumask_t tmp, notcovered;
6713 int n = (i + j) % MAX_NUMNODES;
6715 cpus_complement(notcovered, covered);
6716 cpus_and(tmp, notcovered, *cpu_map);
6717 cpus_and(tmp, tmp, domainspan);
6718 if (cpus_empty(tmp))
6721 nodemask = node_to_cpumask(n);
6722 cpus_and(tmp, tmp, nodemask);
6723 if (cpus_empty(tmp))
6726 sg = kmalloc_node(sizeof(struct sched_group),
6730 "Can not alloc domain group for node %d\n", j);
6733 sg->__cpu_power = 0;
6735 sg->next = prev->next;
6736 cpus_or(covered, covered, tmp);
6743 /* Calculate CPU power for physical packages and nodes */
6744 #ifdef CONFIG_SCHED_SMT
6745 for_each_cpu_mask(i, *cpu_map) {
6746 struct sched_domain *sd = &per_cpu(cpu_domains, i);
6748 init_sched_groups_power(i, sd);
6751 #ifdef CONFIG_SCHED_MC
6752 for_each_cpu_mask(i, *cpu_map) {
6753 struct sched_domain *sd = &per_cpu(core_domains, i);
6755 init_sched_groups_power(i, sd);
6759 for_each_cpu_mask(i, *cpu_map) {
6760 struct sched_domain *sd = &per_cpu(phys_domains, i);
6762 init_sched_groups_power(i, sd);
6766 for (i = 0; i < MAX_NUMNODES; i++)
6767 init_numa_sched_groups_power(sched_group_nodes[i]);
6770 struct sched_group *sg;
6772 cpu_to_allnodes_group(first_cpu(*cpu_map), cpu_map, &sg);
6773 init_numa_sched_groups_power(sg);
6777 /* Attach the domains */
6778 for_each_cpu_mask(i, *cpu_map) {
6779 struct sched_domain *sd;
6780 #ifdef CONFIG_SCHED_SMT
6781 sd = &per_cpu(cpu_domains, i);
6782 #elif defined(CONFIG_SCHED_MC)
6783 sd = &per_cpu(core_domains, i);
6785 sd = &per_cpu(phys_domains, i);
6787 cpu_attach_domain(sd, rd, i);
6794 free_sched_groups(cpu_map);
6799 static cpumask_t *doms_cur; /* current sched domains */
6800 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
6803 * Special case: If a kmalloc of a doms_cur partition (array of
6804 * cpumask_t) fails, then fallback to a single sched domain,
6805 * as determined by the single cpumask_t fallback_doms.
6807 static cpumask_t fallback_doms;
6810 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6811 * For now this just excludes isolated cpus, but could be used to
6812 * exclude other special cases in the future.
6814 static int arch_init_sched_domains(const cpumask_t *cpu_map)
6819 doms_cur = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
6821 doms_cur = &fallback_doms;
6822 cpus_andnot(*doms_cur, *cpu_map, cpu_isolated_map);
6823 err = build_sched_domains(doms_cur);
6824 register_sched_domain_sysctl();
6829 static void arch_destroy_sched_domains(const cpumask_t *cpu_map)
6831 free_sched_groups(cpu_map);
6835 * Detach sched domains from a group of cpus specified in cpu_map
6836 * These cpus will now be attached to the NULL domain
6838 static void detach_destroy_domains(const cpumask_t *cpu_map)
6842 unregister_sched_domain_sysctl();
6844 for_each_cpu_mask(i, *cpu_map)
6845 cpu_attach_domain(NULL, &def_root_domain, i);
6846 synchronize_sched();
6847 arch_destroy_sched_domains(cpu_map);
6851 * Partition sched domains as specified by the 'ndoms_new'
6852 * cpumasks in the array doms_new[] of cpumasks. This compares
6853 * doms_new[] to the current sched domain partitioning, doms_cur[].
6854 * It destroys each deleted domain and builds each new domain.
6856 * 'doms_new' is an array of cpumask_t's of length 'ndoms_new'.
6857 * The masks don't intersect (don't overlap.) We should setup one
6858 * sched domain for each mask. CPUs not in any of the cpumasks will
6859 * not be load balanced. If the same cpumask appears both in the
6860 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6863 * The passed in 'doms_new' should be kmalloc'd. This routine takes
6864 * ownership of it and will kfree it when done with it. If the caller
6865 * failed the kmalloc call, then it can pass in doms_new == NULL,
6866 * and partition_sched_domains() will fallback to the single partition
6869 * Call with hotplug lock held
6871 void partition_sched_domains(int ndoms_new, cpumask_t *doms_new)
6877 /* always unregister in case we don't destroy any domains */
6878 unregister_sched_domain_sysctl();
6880 if (doms_new == NULL) {
6882 doms_new = &fallback_doms;
6883 cpus_andnot(doms_new[0], cpu_online_map, cpu_isolated_map);
6886 /* Destroy deleted domains */
6887 for (i = 0; i < ndoms_cur; i++) {
6888 for (j = 0; j < ndoms_new; j++) {
6889 if (cpus_equal(doms_cur[i], doms_new[j]))
6892 /* no match - a current sched domain not in new doms_new[] */
6893 detach_destroy_domains(doms_cur + i);
6898 /* Build new domains */
6899 for (i = 0; i < ndoms_new; i++) {
6900 for (j = 0; j < ndoms_cur; j++) {
6901 if (cpus_equal(doms_new[i], doms_cur[j]))
6904 /* no match - add a new doms_new */
6905 build_sched_domains(doms_new + i);
6910 /* Remember the new sched domains */
6911 if (doms_cur != &fallback_doms)
6913 doms_cur = doms_new;
6914 ndoms_cur = ndoms_new;
6916 register_sched_domain_sysctl();
6921 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6922 static int arch_reinit_sched_domains(void)
6927 detach_destroy_domains(&cpu_online_map);
6928 err = arch_init_sched_domains(&cpu_online_map);
6934 static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
6938 if (buf[0] != '0' && buf[0] != '1')
6942 sched_smt_power_savings = (buf[0] == '1');
6944 sched_mc_power_savings = (buf[0] == '1');
6946 ret = arch_reinit_sched_domains();
6948 return ret ? ret : count;
6951 #ifdef CONFIG_SCHED_MC
6952 static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page)
6954 return sprintf(page, "%u\n", sched_mc_power_savings);
6956 static ssize_t sched_mc_power_savings_store(struct sys_device *dev,
6957 const char *buf, size_t count)
6959 return sched_power_savings_store(buf, count, 0);
6961 static SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
6962 sched_mc_power_savings_store);
6965 #ifdef CONFIG_SCHED_SMT
6966 static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page)
6968 return sprintf(page, "%u\n", sched_smt_power_savings);
6970 static ssize_t sched_smt_power_savings_store(struct sys_device *dev,
6971 const char *buf, size_t count)
6973 return sched_power_savings_store(buf, count, 1);
6975 static SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
6976 sched_smt_power_savings_store);
6979 int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
6983 #ifdef CONFIG_SCHED_SMT
6985 err = sysfs_create_file(&cls->kset.kobj,
6986 &attr_sched_smt_power_savings.attr);
6988 #ifdef CONFIG_SCHED_MC
6989 if (!err && mc_capable())
6990 err = sysfs_create_file(&cls->kset.kobj,
6991 &attr_sched_mc_power_savings.attr);
6998 * Force a reinitialization of the sched domains hierarchy. The domains
6999 * and groups cannot be updated in place without racing with the balancing
7000 * code, so we temporarily attach all running cpus to the NULL domain
7001 * which will prevent rebalancing while the sched domains are recalculated.
7003 static int update_sched_domains(struct notifier_block *nfb,
7004 unsigned long action, void *hcpu)
7007 case CPU_UP_PREPARE:
7008 case CPU_UP_PREPARE_FROZEN:
7009 case CPU_DOWN_PREPARE:
7010 case CPU_DOWN_PREPARE_FROZEN:
7011 detach_destroy_domains(&cpu_online_map);
7014 case CPU_UP_CANCELED:
7015 case CPU_UP_CANCELED_FROZEN:
7016 case CPU_DOWN_FAILED:
7017 case CPU_DOWN_FAILED_FROZEN:
7019 case CPU_ONLINE_FROZEN:
7021 case CPU_DEAD_FROZEN:
7023 * Fall through and re-initialise the domains.
7030 /* The hotplug lock is already held by cpu_up/cpu_down */
7031 arch_init_sched_domains(&cpu_online_map);
7036 void __init sched_init_smp(void)
7038 cpumask_t non_isolated_cpus;
7041 arch_init_sched_domains(&cpu_online_map);
7042 cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
7043 if (cpus_empty(non_isolated_cpus))
7044 cpu_set(smp_processor_id(), non_isolated_cpus);
7046 /* XXX: Theoretical race here - CPU may be hotplugged now */
7047 hotcpu_notifier(update_sched_domains, 0);
7049 /* Move init over to a non-isolated CPU */
7050 if (set_cpus_allowed(current, non_isolated_cpus) < 0)
7052 sched_init_granularity();
7054 #ifdef CONFIG_FAIR_GROUP_SCHED
7055 if (nr_cpu_ids == 1)
7058 lb_monitor_task = kthread_create(load_balance_monitor, NULL,
7060 if (!IS_ERR(lb_monitor_task)) {
7061 lb_monitor_task->flags |= PF_NOFREEZE;
7062 wake_up_process(lb_monitor_task);
7064 printk(KERN_ERR "Could not create load balance monitor thread"
7065 "(error = %ld) \n", PTR_ERR(lb_monitor_task));
7070 void __init sched_init_smp(void)
7072 sched_init_granularity();
7074 #endif /* CONFIG_SMP */
7076 int in_sched_functions(unsigned long addr)
7078 return in_lock_functions(addr) ||
7079 (addr >= (unsigned long)__sched_text_start
7080 && addr < (unsigned long)__sched_text_end);
7083 static void init_cfs_rq(struct cfs_rq *cfs_rq, struct rq *rq)
7085 cfs_rq->tasks_timeline = RB_ROOT;
7086 #ifdef CONFIG_FAIR_GROUP_SCHED
7089 cfs_rq->min_vruntime = (u64)(-(1LL << 20));
7092 static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
7094 struct rt_prio_array *array;
7097 array = &rt_rq->active;
7098 for (i = 0; i < MAX_RT_PRIO; i++) {
7099 INIT_LIST_HEAD(array->queue + i);
7100 __clear_bit(i, array->bitmap);
7102 /* delimiter for bitsearch: */
7103 __set_bit(MAX_RT_PRIO, array->bitmap);
7106 rt_rq->rt_nr_migratory = 0;
7107 rt_rq->highest_prio = MAX_RT_PRIO;
7108 rt_rq->overloaded = 0;
7112 rt_rq->rt_throttled = 0;
7114 #ifdef CONFIG_FAIR_GROUP_SCHED
7119 #ifdef CONFIG_FAIR_GROUP_SCHED
7120 static void init_tg_cfs_entry(struct rq *rq, struct task_group *tg,
7121 struct cfs_rq *cfs_rq, struct sched_entity *se,
7124 tg->cfs_rq[cpu] = cfs_rq;
7125 init_cfs_rq(cfs_rq, rq);
7128 list_add(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
7131 se->cfs_rq = &rq->cfs;
7133 se->load.weight = tg->shares;
7134 se->load.inv_weight = div64_64(1ULL<<32, se->load.weight);
7138 static void init_tg_rt_entry(struct rq *rq, struct task_group *tg,
7139 struct rt_rq *rt_rq, struct sched_rt_entity *rt_se,
7142 tg->rt_rq[cpu] = rt_rq;
7143 init_rt_rq(rt_rq, rq);
7145 rt_rq->rt_se = rt_se;
7147 list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
7149 tg->rt_se[cpu] = rt_se;
7150 rt_se->rt_rq = &rq->rt;
7151 rt_se->my_q = rt_rq;
7152 rt_se->parent = NULL;
7153 INIT_LIST_HEAD(&rt_se->run_list);
7157 void __init sched_init(void)
7159 int highest_cpu = 0;
7163 init_defrootdomain();
7166 #ifdef CONFIG_FAIR_GROUP_SCHED
7167 list_add(&init_task_group.list, &task_groups);
7170 for_each_possible_cpu(i) {
7174 spin_lock_init(&rq->lock);
7175 lockdep_set_class(&rq->lock, &rq->rq_lock_key);
7178 init_cfs_rq(&rq->cfs, rq);
7179 init_rt_rq(&rq->rt, rq);
7180 #ifdef CONFIG_FAIR_GROUP_SCHED
7181 init_task_group.shares = init_task_group_load;
7182 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
7183 init_tg_cfs_entry(rq, &init_task_group,
7184 &per_cpu(init_cfs_rq, i),
7185 &per_cpu(init_sched_entity, i), i, 1);
7187 init_task_group.rt_ratio = sysctl_sched_rt_ratio; /* XXX */
7188 INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
7189 init_tg_rt_entry(rq, &init_task_group,
7190 &per_cpu(init_rt_rq, i),
7191 &per_cpu(init_sched_rt_entity, i), i, 1);
7193 rq->rt_period_expire = 0;
7195 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
7196 rq->cpu_load[j] = 0;
7200 rq->active_balance = 0;
7201 rq->next_balance = jiffies;
7204 rq->migration_thread = NULL;
7205 INIT_LIST_HEAD(&rq->migration_queue);
7206 rq_attach_root(rq, &def_root_domain);
7209 atomic_set(&rq->nr_iowait, 0);
7213 set_load_weight(&init_task);
7215 #ifdef CONFIG_PREEMPT_NOTIFIERS
7216 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
7220 nr_cpu_ids = highest_cpu + 1;
7221 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL);
7224 #ifdef CONFIG_RT_MUTEXES
7225 plist_head_init(&init_task.pi_waiters, &init_task.pi_lock);
7229 * The boot idle thread does lazy MMU switching as well:
7231 atomic_inc(&init_mm.mm_count);
7232 enter_lazy_tlb(&init_mm, current);
7235 * Make us the idle thread. Technically, schedule() should not be
7236 * called from this thread, however somewhere below it might be,
7237 * but because we are the idle thread, we just pick up running again
7238 * when this runqueue becomes "idle".
7240 init_idle(current, smp_processor_id());
7242 * During early bootup we pretend to be a normal task:
7244 current->sched_class = &fair_sched_class;
7247 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
7248 void __might_sleep(char *file, int line)
7251 static unsigned long prev_jiffy; /* ratelimiting */
7253 if ((in_atomic() || irqs_disabled()) &&
7254 system_state == SYSTEM_RUNNING && !oops_in_progress) {
7255 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
7257 prev_jiffy = jiffies;
7258 printk(KERN_ERR "BUG: sleeping function called from invalid"
7259 " context at %s:%d\n", file, line);
7260 printk("in_atomic():%d, irqs_disabled():%d\n",
7261 in_atomic(), irqs_disabled());
7262 debug_show_held_locks(current);
7263 if (irqs_disabled())
7264 print_irqtrace_events(current);
7269 EXPORT_SYMBOL(__might_sleep);
7272 #ifdef CONFIG_MAGIC_SYSRQ
7273 static void normalize_task(struct rq *rq, struct task_struct *p)
7276 update_rq_clock(rq);
7277 on_rq = p->se.on_rq;
7279 deactivate_task(rq, p, 0);
7280 __setscheduler(rq, p, SCHED_NORMAL, 0);
7282 activate_task(rq, p, 0);
7283 resched_task(rq->curr);
7287 void normalize_rt_tasks(void)
7289 struct task_struct *g, *p;
7290 unsigned long flags;
7293 read_lock_irq(&tasklist_lock);
7294 do_each_thread(g, p) {
7296 * Only normalize user tasks:
7301 p->se.exec_start = 0;
7302 #ifdef CONFIG_SCHEDSTATS
7303 p->se.wait_start = 0;
7304 p->se.sleep_start = 0;
7305 p->se.block_start = 0;
7307 task_rq(p)->clock = 0;
7311 * Renice negative nice level userspace
7314 if (TASK_NICE(p) < 0 && p->mm)
7315 set_user_nice(p, 0);
7319 spin_lock_irqsave(&p->pi_lock, flags);
7320 rq = __task_rq_lock(p);
7322 normalize_task(rq, p);
7324 __task_rq_unlock(rq);
7325 spin_unlock_irqrestore(&p->pi_lock, flags);
7326 } while_each_thread(g, p);
7328 read_unlock_irq(&tasklist_lock);
7331 #endif /* CONFIG_MAGIC_SYSRQ */
7335 * These functions are only useful for the IA64 MCA handling.
7337 * They can only be called when the whole system has been
7338 * stopped - every CPU needs to be quiescent, and no scheduling
7339 * activity can take place. Using them for anything else would
7340 * be a serious bug, and as a result, they aren't even visible
7341 * under any other configuration.
7345 * curr_task - return the current task for a given cpu.
7346 * @cpu: the processor in question.
7348 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7350 struct task_struct *curr_task(int cpu)
7352 return cpu_curr(cpu);
7356 * set_curr_task - set the current task for a given cpu.
7357 * @cpu: the processor in question.
7358 * @p: the task pointer to set.
7360 * Description: This function must only be used when non-maskable interrupts
7361 * are serviced on a separate stack. It allows the architecture to switch the
7362 * notion of the current task on a cpu in a non-blocking manner. This function
7363 * must be called with all CPU's synchronized, and interrupts disabled, the
7364 * and caller must save the original value of the current task (see
7365 * curr_task() above) and restore that value before reenabling interrupts and
7366 * re-starting the system.
7368 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7370 void set_curr_task(int cpu, struct task_struct *p)
7377 #ifdef CONFIG_FAIR_GROUP_SCHED
7381 * distribute shares of all task groups among their schedulable entities,
7382 * to reflect load distribution across cpus.
7384 static int rebalance_shares(struct sched_domain *sd, int this_cpu)
7386 struct cfs_rq *cfs_rq;
7387 struct rq *rq = cpu_rq(this_cpu);
7388 cpumask_t sdspan = sd->span;
7391 /* Walk thr' all the task groups that we have */
7392 for_each_leaf_cfs_rq(rq, cfs_rq) {
7394 unsigned long total_load = 0, total_shares;
7395 struct task_group *tg = cfs_rq->tg;
7397 /* Gather total task load of this group across cpus */
7398 for_each_cpu_mask(i, sdspan)
7399 total_load += tg->cfs_rq[i]->load.weight;
7401 /* Nothing to do if this group has no load */
7406 * tg->shares represents the number of cpu shares the task group
7407 * is eligible to hold on a single cpu. On N cpus, it is
7408 * eligible to hold (N * tg->shares) number of cpu shares.
7410 total_shares = tg->shares * cpus_weight(sdspan);
7413 * redistribute total_shares across cpus as per the task load
7416 for_each_cpu_mask(i, sdspan) {
7417 unsigned long local_load, local_shares;
7419 local_load = tg->cfs_rq[i]->load.weight;
7420 local_shares = (local_load * total_shares) / total_load;
7422 local_shares = MIN_GROUP_SHARES;
7423 if (local_shares == tg->se[i]->load.weight)
7426 spin_lock_irq(&cpu_rq(i)->lock);
7427 set_se_shares(tg->se[i], local_shares);
7428 spin_unlock_irq(&cpu_rq(i)->lock);
7437 * How frequently should we rebalance_shares() across cpus?
7439 * The more frequently we rebalance shares, the more accurate is the fairness
7440 * of cpu bandwidth distribution between task groups. However higher frequency
7441 * also implies increased scheduling overhead.
7443 * sysctl_sched_min_bal_int_shares represents the minimum interval between
7444 * consecutive calls to rebalance_shares() in the same sched domain.
7446 * sysctl_sched_max_bal_int_shares represents the maximum interval between
7447 * consecutive calls to rebalance_shares() in the same sched domain.
7449 * These settings allows for the appropriate trade-off between accuracy of
7450 * fairness and the associated overhead.
7454 /* default: 8ms, units: milliseconds */
7455 const_debug unsigned int sysctl_sched_min_bal_int_shares = 8;
7457 /* default: 128ms, units: milliseconds */
7458 const_debug unsigned int sysctl_sched_max_bal_int_shares = 128;
7460 /* kernel thread that runs rebalance_shares() periodically */
7461 static int load_balance_monitor(void *unused)
7463 unsigned int timeout = sysctl_sched_min_bal_int_shares;
7464 struct sched_param schedparm;
7468 * We don't want this thread's execution to be limited by the shares
7469 * assigned to default group (init_task_group). Hence make it run
7470 * as a SCHED_RR RT task at the lowest priority.
7472 schedparm.sched_priority = 1;
7473 ret = sched_setscheduler(current, SCHED_RR, &schedparm);
7475 printk(KERN_ERR "Couldn't set SCHED_RR policy for load balance"
7476 " monitor thread (error = %d) \n", ret);
7478 while (!kthread_should_stop()) {
7479 int i, cpu, balanced = 1;
7481 /* Prevent cpus going down or coming up */
7483 /* lockout changes to doms_cur[] array */
7486 * Enter a rcu read-side critical section to safely walk rq->sd
7487 * chain on various cpus and to walk task group list
7488 * (rq->leaf_cfs_rq_list) in rebalance_shares().
7492 for (i = 0; i < ndoms_cur; i++) {
7493 cpumask_t cpumap = doms_cur[i];
7494 struct sched_domain *sd = NULL, *sd_prev = NULL;
7496 cpu = first_cpu(cpumap);
7498 /* Find the highest domain at which to balance shares */
7499 for_each_domain(cpu, sd) {
7500 if (!(sd->flags & SD_LOAD_BALANCE))
7506 /* sd == NULL? No load balance reqd in this domain */
7510 balanced &= rebalance_shares(sd, cpu);
7519 timeout = sysctl_sched_min_bal_int_shares;
7520 else if (timeout < sysctl_sched_max_bal_int_shares)
7523 msleep_interruptible(timeout);
7528 #endif /* CONFIG_SMP */
7530 static void free_sched_group(struct task_group *tg)
7534 for_each_possible_cpu(i) {
7536 kfree(tg->cfs_rq[i]);
7540 kfree(tg->rt_rq[i]);
7542 kfree(tg->rt_se[i]);
7552 /* allocate runqueue etc for a new task group */
7553 struct task_group *sched_create_group(void)
7555 struct task_group *tg;
7556 struct cfs_rq *cfs_rq;
7557 struct sched_entity *se;
7558 struct rt_rq *rt_rq;
7559 struct sched_rt_entity *rt_se;
7563 tg = kzalloc(sizeof(*tg), GFP_KERNEL);
7565 return ERR_PTR(-ENOMEM);
7567 tg->cfs_rq = kzalloc(sizeof(cfs_rq) * NR_CPUS, GFP_KERNEL);
7570 tg->se = kzalloc(sizeof(se) * NR_CPUS, GFP_KERNEL);
7573 tg->rt_rq = kzalloc(sizeof(rt_rq) * NR_CPUS, GFP_KERNEL);
7576 tg->rt_se = kzalloc(sizeof(rt_se) * NR_CPUS, GFP_KERNEL);
7580 tg->shares = NICE_0_LOAD;
7581 tg->rt_ratio = 0; /* XXX */
7583 for_each_possible_cpu(i) {
7586 cfs_rq = kmalloc_node(sizeof(struct cfs_rq),
7587 GFP_KERNEL|__GFP_ZERO, cpu_to_node(i));
7591 se = kmalloc_node(sizeof(struct sched_entity),
7592 GFP_KERNEL|__GFP_ZERO, cpu_to_node(i));
7596 rt_rq = kmalloc_node(sizeof(struct rt_rq),
7597 GFP_KERNEL|__GFP_ZERO, cpu_to_node(i));
7601 rt_se = kmalloc_node(sizeof(struct sched_rt_entity),
7602 GFP_KERNEL|__GFP_ZERO, cpu_to_node(i));
7606 init_tg_cfs_entry(rq, tg, cfs_rq, se, i, 0);
7607 init_tg_rt_entry(rq, tg, rt_rq, rt_se, i, 0);
7610 lock_task_group_list();
7611 for_each_possible_cpu(i) {
7613 cfs_rq = tg->cfs_rq[i];
7614 list_add_rcu(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
7615 rt_rq = tg->rt_rq[i];
7616 list_add_rcu(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
7618 list_add_rcu(&tg->list, &task_groups);
7619 unlock_task_group_list();
7624 free_sched_group(tg);
7625 return ERR_PTR(-ENOMEM);
7628 /* rcu callback to free various structures associated with a task group */
7629 static void free_sched_group_rcu(struct rcu_head *rhp)
7631 /* now it should be safe to free those cfs_rqs */
7632 free_sched_group(container_of(rhp, struct task_group, rcu));
7635 /* Destroy runqueue etc associated with a task group */
7636 void sched_destroy_group(struct task_group *tg)
7638 struct cfs_rq *cfs_rq = NULL;
7639 struct rt_rq *rt_rq = NULL;
7642 lock_task_group_list();
7643 for_each_possible_cpu(i) {
7644 cfs_rq = tg->cfs_rq[i];
7645 list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
7646 rt_rq = tg->rt_rq[i];
7647 list_del_rcu(&rt_rq->leaf_rt_rq_list);
7649 list_del_rcu(&tg->list);
7650 unlock_task_group_list();
7654 /* wait for possible concurrent references to cfs_rqs complete */
7655 call_rcu(&tg->rcu, free_sched_group_rcu);
7658 /* change task's runqueue when it moves between groups.
7659 * The caller of this function should have put the task in its new group
7660 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7661 * reflect its new group.
7663 void sched_move_task(struct task_struct *tsk)
7666 unsigned long flags;
7669 rq = task_rq_lock(tsk, &flags);
7671 update_rq_clock(rq);
7673 running = task_current(rq, tsk);
7674 on_rq = tsk->se.on_rq;
7677 dequeue_task(rq, tsk, 0);
7678 if (unlikely(running))
7679 tsk->sched_class->put_prev_task(rq, tsk);
7682 set_task_rq(tsk, task_cpu(tsk));
7685 if (unlikely(running))
7686 tsk->sched_class->set_curr_task(rq);
7687 enqueue_task(rq, tsk, 0);
7690 task_rq_unlock(rq, &flags);
7693 /* rq->lock to be locked by caller */
7694 static void set_se_shares(struct sched_entity *se, unsigned long shares)
7696 struct cfs_rq *cfs_rq = se->cfs_rq;
7697 struct rq *rq = cfs_rq->rq;
7701 shares = MIN_GROUP_SHARES;
7705 dequeue_entity(cfs_rq, se, 0);
7706 dec_cpu_load(rq, se->load.weight);
7709 se->load.weight = shares;
7710 se->load.inv_weight = div64_64((1ULL<<32), shares);
7713 enqueue_entity(cfs_rq, se, 0);
7714 inc_cpu_load(rq, se->load.weight);
7718 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
7721 struct cfs_rq *cfs_rq;
7724 lock_task_group_list();
7725 if (tg->shares == shares)
7728 if (shares < MIN_GROUP_SHARES)
7729 shares = MIN_GROUP_SHARES;
7732 * Prevent any load balance activity (rebalance_shares,
7733 * load_balance_fair) from referring to this group first,
7734 * by taking it off the rq->leaf_cfs_rq_list on each cpu.
7736 for_each_possible_cpu(i) {
7737 cfs_rq = tg->cfs_rq[i];
7738 list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
7741 /* wait for any ongoing reference to this group to finish */
7742 synchronize_sched();
7745 * Now we are free to modify the group's share on each cpu
7746 * w/o tripping rebalance_share or load_balance_fair.
7748 tg->shares = shares;
7749 for_each_possible_cpu(i) {
7750 spin_lock_irq(&cpu_rq(i)->lock);
7751 set_se_shares(tg->se[i], shares);
7752 spin_unlock_irq(&cpu_rq(i)->lock);
7756 * Enable load balance activity on this group, by inserting it back on
7757 * each cpu's rq->leaf_cfs_rq_list.
7759 for_each_possible_cpu(i) {
7761 cfs_rq = tg->cfs_rq[i];
7762 list_add_rcu(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
7765 unlock_task_group_list();
7769 unsigned long sched_group_shares(struct task_group *tg)
7775 * Ensure the total rt_ratio <= sysctl_sched_rt_ratio
7777 int sched_group_set_rt_ratio(struct task_group *tg, unsigned long rt_ratio)
7779 struct task_group *tgi;
7780 unsigned long total = 0;
7783 list_for_each_entry_rcu(tgi, &task_groups, list)
7784 total += tgi->rt_ratio;
7787 if (total + rt_ratio - tg->rt_ratio > sysctl_sched_rt_ratio)
7790 tg->rt_ratio = rt_ratio;
7794 unsigned long sched_group_rt_ratio(struct task_group *tg)
7796 return tg->rt_ratio;
7799 #endif /* CONFIG_FAIR_GROUP_SCHED */
7801 #ifdef CONFIG_FAIR_CGROUP_SCHED
7803 /* return corresponding task_group object of a cgroup */
7804 static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
7806 return container_of(cgroup_subsys_state(cgrp, cpu_cgroup_subsys_id),
7807 struct task_group, css);
7810 static struct cgroup_subsys_state *
7811 cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
7813 struct task_group *tg;
7815 if (!cgrp->parent) {
7816 /* This is early initialization for the top cgroup */
7817 init_task_group.css.cgroup = cgrp;
7818 return &init_task_group.css;
7821 /* we support only 1-level deep hierarchical scheduler atm */
7822 if (cgrp->parent->parent)
7823 return ERR_PTR(-EINVAL);
7825 tg = sched_create_group();
7827 return ERR_PTR(-ENOMEM);
7829 /* Bind the cgroup to task_group object we just created */
7830 tg->css.cgroup = cgrp;
7836 cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
7838 struct task_group *tg = cgroup_tg(cgrp);
7840 sched_destroy_group(tg);
7844 cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
7845 struct task_struct *tsk)
7847 /* We don't support RT-tasks being in separate groups */
7848 if (tsk->sched_class != &fair_sched_class)
7855 cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
7856 struct cgroup *old_cont, struct task_struct *tsk)
7858 sched_move_task(tsk);
7861 static int cpu_shares_write_uint(struct cgroup *cgrp, struct cftype *cftype,
7864 return sched_group_set_shares(cgroup_tg(cgrp), shareval);
7867 static u64 cpu_shares_read_uint(struct cgroup *cgrp, struct cftype *cft)
7869 struct task_group *tg = cgroup_tg(cgrp);
7871 return (u64) tg->shares;
7874 static int cpu_rt_ratio_write_uint(struct cgroup *cgrp, struct cftype *cftype,
7877 return sched_group_set_rt_ratio(cgroup_tg(cgrp), rt_ratio_val);
7880 static u64 cpu_rt_ratio_read_uint(struct cgroup *cgrp, struct cftype *cft)
7882 struct task_group *tg = cgroup_tg(cgrp);
7884 return (u64) tg->rt_ratio;
7887 static struct cftype cpu_files[] = {
7890 .read_uint = cpu_shares_read_uint,
7891 .write_uint = cpu_shares_write_uint,
7895 .read_uint = cpu_rt_ratio_read_uint,
7896 .write_uint = cpu_rt_ratio_write_uint,
7900 static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
7902 return cgroup_add_files(cont, ss, cpu_files, ARRAY_SIZE(cpu_files));
7905 struct cgroup_subsys cpu_cgroup_subsys = {
7907 .create = cpu_cgroup_create,
7908 .destroy = cpu_cgroup_destroy,
7909 .can_attach = cpu_cgroup_can_attach,
7910 .attach = cpu_cgroup_attach,
7911 .populate = cpu_cgroup_populate,
7912 .subsys_id = cpu_cgroup_subsys_id,
7916 #endif /* CONFIG_FAIR_CGROUP_SCHED */
7918 #ifdef CONFIG_CGROUP_CPUACCT
7921 * CPU accounting code for task groups.
7923 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
7924 * (balbir@in.ibm.com).
7927 /* track cpu usage of a group of tasks */
7929 struct cgroup_subsys_state css;
7930 /* cpuusage holds pointer to a u64-type object on every cpu */
7934 struct cgroup_subsys cpuacct_subsys;
7936 /* return cpu accounting group corresponding to this container */
7937 static inline struct cpuacct *cgroup_ca(struct cgroup *cont)
7939 return container_of(cgroup_subsys_state(cont, cpuacct_subsys_id),
7940 struct cpuacct, css);
7943 /* return cpu accounting group to which this task belongs */
7944 static inline struct cpuacct *task_ca(struct task_struct *tsk)
7946 return container_of(task_subsys_state(tsk, cpuacct_subsys_id),
7947 struct cpuacct, css);
7950 /* create a new cpu accounting group */
7951 static struct cgroup_subsys_state *cpuacct_create(
7952 struct cgroup_subsys *ss, struct cgroup *cont)
7954 struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
7957 return ERR_PTR(-ENOMEM);
7959 ca->cpuusage = alloc_percpu(u64);
7960 if (!ca->cpuusage) {
7962 return ERR_PTR(-ENOMEM);
7968 /* destroy an existing cpu accounting group */
7970 cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
7972 struct cpuacct *ca = cgroup_ca(cont);
7974 free_percpu(ca->cpuusage);
7978 /* return total cpu usage (in nanoseconds) of a group */
7979 static u64 cpuusage_read(struct cgroup *cont, struct cftype *cft)
7981 struct cpuacct *ca = cgroup_ca(cont);
7982 u64 totalcpuusage = 0;
7985 for_each_possible_cpu(i) {
7986 u64 *cpuusage = percpu_ptr(ca->cpuusage, i);
7989 * Take rq->lock to make 64-bit addition safe on 32-bit
7992 spin_lock_irq(&cpu_rq(i)->lock);
7993 totalcpuusage += *cpuusage;
7994 spin_unlock_irq(&cpu_rq(i)->lock);
7997 return totalcpuusage;
8000 static struct cftype files[] = {
8003 .read_uint = cpuusage_read,
8007 static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cont)
8009 return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
8013 * charge this task's execution time to its accounting group.
8015 * called with rq->lock held.
8017 static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
8021 if (!cpuacct_subsys.active)
8026 u64 *cpuusage = percpu_ptr(ca->cpuusage, task_cpu(tsk));
8028 *cpuusage += cputime;
8032 struct cgroup_subsys cpuacct_subsys = {
8034 .create = cpuacct_create,
8035 .destroy = cpuacct_destroy,
8036 .populate = cpuacct_populate,
8037 .subsys_id = cpuacct_subsys_id,
8039 #endif /* CONFIG_CGROUP_CPUACCT */