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
28 #include <linux/module.h>
29 #include <linux/nmi.h>
30 #include <linux/init.h>
31 #include <linux/uaccess.h>
32 #include <linux/highmem.h>
33 #include <linux/smp_lock.h>
34 #include <asm/mmu_context.h>
35 #include <linux/interrupt.h>
36 #include <linux/capability.h>
37 #include <linux/completion.h>
38 #include <linux/kernel_stat.h>
39 #include <linux/debug_locks.h>
40 #include <linux/security.h>
41 #include <linux/notifier.h>
42 #include <linux/profile.h>
43 #include <linux/freezer.h>
44 #include <linux/vmalloc.h>
45 #include <linux/blkdev.h>
46 #include <linux/delay.h>
47 #include <linux/smp.h>
48 #include <linux/threads.h>
49 #include <linux/timer.h>
50 #include <linux/rcupdate.h>
51 #include <linux/cpu.h>
52 #include <linux/cpuset.h>
53 #include <linux/percpu.h>
54 #include <linux/kthread.h>
55 #include <linux/seq_file.h>
56 #include <linux/syscalls.h>
57 #include <linux/times.h>
58 #include <linux/tsacct_kern.h>
59 #include <linux/kprobes.h>
60 #include <linux/delayacct.h>
61 #include <linux/reciprocal_div.h>
62 #include <linux/unistd.h>
67 * Scheduler clock - returns current time in nanosec units.
68 * This is default implementation.
69 * Architectures and sub-architectures can override this.
71 unsigned long long __attribute__((weak)) sched_clock(void)
73 return (unsigned long long)jiffies * (1000000000 / HZ);
77 * Convert user-nice values [ -20 ... 0 ... 19 ]
78 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
81 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
82 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
83 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
86 * 'User priority' is the nice value converted to something we
87 * can work with better when scaling various scheduler parameters,
88 * it's a [ 0 ... 39 ] range.
90 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
91 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
92 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
95 * Some helpers for converting nanosecond timing to jiffy resolution
97 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
98 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
100 #define NICE_0_LOAD SCHED_LOAD_SCALE
101 #define NICE_0_SHIFT SCHED_LOAD_SHIFT
104 * These are the 'tuning knobs' of the scheduler:
106 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
107 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
108 * Timeslices get refilled after they expire.
110 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
111 #define DEF_TIMESLICE (100 * HZ / 1000)
115 * Divide a load by a sched group cpu_power : (load / sg->__cpu_power)
116 * Since cpu_power is a 'constant', we can use a reciprocal divide.
118 static inline u32 sg_div_cpu_power(const struct sched_group *sg, u32 load)
120 return reciprocal_divide(load, sg->reciprocal_cpu_power);
124 * Each time a sched group cpu_power is changed,
125 * we must compute its reciprocal value
127 static inline void sg_inc_cpu_power(struct sched_group *sg, u32 val)
129 sg->__cpu_power += val;
130 sg->reciprocal_cpu_power = reciprocal_value(sg->__cpu_power);
134 #define SCALE_PRIO(x, prio) \
135 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
138 * static_prio_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
139 * to time slice values: [800ms ... 100ms ... 5ms]
141 static unsigned int static_prio_timeslice(int static_prio)
143 if (static_prio == NICE_TO_PRIO(19))
146 if (static_prio < NICE_TO_PRIO(0))
147 return SCALE_PRIO(DEF_TIMESLICE * 4, static_prio);
149 return SCALE_PRIO(DEF_TIMESLICE, static_prio);
152 static inline int rt_policy(int policy)
154 if (unlikely(policy == SCHED_FIFO) || unlikely(policy == SCHED_RR))
159 static inline int task_has_rt_policy(struct task_struct *p)
161 return rt_policy(p->policy);
165 * This is the priority-queue data structure of the RT scheduling class:
167 struct rt_prio_array {
168 DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
169 struct list_head queue[MAX_RT_PRIO];
173 struct load_weight load;
174 u64 load_update_start, load_update_last;
175 unsigned long delta_fair, delta_exec, delta_stat;
178 /* CFS-related fields in a runqueue */
180 struct load_weight load;
181 unsigned long nr_running;
187 unsigned long wait_runtime_overruns, wait_runtime_underruns;
189 struct rb_root tasks_timeline;
190 struct rb_node *rb_leftmost;
191 struct rb_node *rb_load_balance_curr;
192 #ifdef CONFIG_FAIR_GROUP_SCHED
193 /* 'curr' points to currently running entity on this cfs_rq.
194 * It is set to NULL otherwise (i.e when none are currently running).
196 struct sched_entity *curr;
197 struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
199 /* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
200 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
201 * (like users, containers etc.)
203 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
204 * list is used during load balance.
206 struct list_head leaf_cfs_rq_list; /* Better name : task_cfs_rq_list? */
210 /* Real-Time classes' related field in a runqueue: */
212 struct rt_prio_array active;
213 int rt_load_balance_idx;
214 struct list_head *rt_load_balance_head, *rt_load_balance_curr;
218 * This is the main, per-CPU runqueue data structure.
220 * Locking rule: those places that want to lock multiple runqueues
221 * (such as the load balancing or the thread migration code), lock
222 * acquire operations must be ordered by ascending &runqueue.
225 spinlock_t lock; /* runqueue lock */
228 * nr_running and cpu_load should be in the same cacheline because
229 * remote CPUs use both these fields when doing load calculation.
231 unsigned long nr_running;
232 #define CPU_LOAD_IDX_MAX 5
233 unsigned long cpu_load[CPU_LOAD_IDX_MAX];
234 unsigned char idle_at_tick;
236 unsigned char in_nohz_recently;
238 struct load_stat ls; /* capture load from *all* tasks on this cpu */
239 unsigned long nr_load_updates;
243 #ifdef CONFIG_FAIR_GROUP_SCHED
244 struct list_head leaf_cfs_rq_list; /* list of leaf cfs_rq on this cpu */
249 * This is part of a global counter where only the total sum
250 * over all CPUs matters. A task can increase this counter on
251 * one CPU and if it got migrated afterwards it may decrease
252 * it on another CPU. Always updated under the runqueue lock:
254 unsigned long nr_uninterruptible;
256 struct task_struct *curr, *idle;
257 unsigned long next_balance;
258 struct mm_struct *prev_mm;
260 u64 clock, prev_clock_raw;
263 unsigned int clock_warps, clock_overflows;
264 unsigned int clock_unstable_events;
266 struct sched_class *load_balance_class;
271 struct sched_domain *sd;
273 /* For active balancing */
276 int cpu; /* cpu of this runqueue */
278 struct task_struct *migration_thread;
279 struct list_head migration_queue;
282 #ifdef CONFIG_SCHEDSTATS
284 struct sched_info rq_sched_info;
286 /* sys_sched_yield() stats */
287 unsigned long yld_exp_empty;
288 unsigned long yld_act_empty;
289 unsigned long yld_both_empty;
290 unsigned long yld_cnt;
292 /* schedule() stats */
293 unsigned long sched_switch;
294 unsigned long sched_cnt;
295 unsigned long sched_goidle;
297 /* try_to_wake_up() stats */
298 unsigned long ttwu_cnt;
299 unsigned long ttwu_local;
301 struct lock_class_key rq_lock_key;
304 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
305 static DEFINE_MUTEX(sched_hotcpu_mutex);
307 static inline void check_preempt_curr(struct rq *rq, struct task_struct *p)
309 rq->curr->sched_class->check_preempt_curr(rq, p);
312 static inline int cpu_of(struct rq *rq)
322 * Per-runqueue clock, as finegrained as the platform can give us:
324 static unsigned long long __rq_clock(struct rq *rq)
326 u64 prev_raw = rq->prev_clock_raw;
327 u64 now = sched_clock();
328 s64 delta = now - prev_raw;
329 u64 clock = rq->clock;
332 * Protect against sched_clock() occasionally going backwards:
334 if (unlikely(delta < 0)) {
339 * Catch too large forward jumps too:
341 if (unlikely(delta > 2*TICK_NSEC)) {
343 rq->clock_overflows++;
345 if (unlikely(delta > rq->clock_max_delta))
346 rq->clock_max_delta = delta;
351 rq->prev_clock_raw = now;
357 static inline unsigned long long rq_clock(struct rq *rq)
359 int this_cpu = smp_processor_id();
361 if (this_cpu == cpu_of(rq))
362 return __rq_clock(rq);
368 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
369 * See detach_destroy_domains: synchronize_sched for details.
371 * The domain tree of any CPU may only be accessed from within
372 * preempt-disabled sections.
374 #define for_each_domain(cpu, __sd) \
375 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
377 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
378 #define this_rq() (&__get_cpu_var(runqueues))
379 #define task_rq(p) cpu_rq(task_cpu(p))
380 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
382 #ifdef CONFIG_FAIR_GROUP_SCHED
383 /* Change a task's ->cfs_rq if it moves across CPUs */
384 static inline void set_task_cfs_rq(struct task_struct *p)
386 p->se.cfs_rq = &task_rq(p)->cfs;
389 static inline void set_task_cfs_rq(struct task_struct *p)
394 #ifndef prepare_arch_switch
395 # define prepare_arch_switch(next) do { } while (0)
397 #ifndef finish_arch_switch
398 # define finish_arch_switch(prev) do { } while (0)
401 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
402 static inline int task_running(struct rq *rq, struct task_struct *p)
404 return rq->curr == p;
407 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
411 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
413 #ifdef CONFIG_DEBUG_SPINLOCK
414 /* this is a valid case when another task releases the spinlock */
415 rq->lock.owner = current;
418 * If we are tracking spinlock dependencies then we have to
419 * fix up the runqueue lock - which gets 'carried over' from
422 spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
424 spin_unlock_irq(&rq->lock);
427 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
428 static inline int task_running(struct rq *rq, struct task_struct *p)
433 return rq->curr == p;
437 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
441 * We can optimise this out completely for !SMP, because the
442 * SMP rebalancing from interrupt is the only thing that cares
447 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
448 spin_unlock_irq(&rq->lock);
450 spin_unlock(&rq->lock);
454 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
458 * After ->oncpu is cleared, the task can be moved to a different CPU.
459 * We must ensure this doesn't happen until the switch is completely
465 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
469 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
472 * __task_rq_lock - lock the runqueue a given task resides on.
473 * Must be called interrupts disabled.
475 static inline struct rq *__task_rq_lock(struct task_struct *p)
482 spin_lock(&rq->lock);
483 if (unlikely(rq != task_rq(p))) {
484 spin_unlock(&rq->lock);
485 goto repeat_lock_task;
491 * task_rq_lock - lock the runqueue a given task resides on and disable
492 * interrupts. Note the ordering: we can safely lookup the task_rq without
493 * explicitly disabling preemption.
495 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
501 local_irq_save(*flags);
503 spin_lock(&rq->lock);
504 if (unlikely(rq != task_rq(p))) {
505 spin_unlock_irqrestore(&rq->lock, *flags);
506 goto repeat_lock_task;
511 static inline void __task_rq_unlock(struct rq *rq)
514 spin_unlock(&rq->lock);
517 static inline void task_rq_unlock(struct rq *rq, unsigned long *flags)
520 spin_unlock_irqrestore(&rq->lock, *flags);
524 * this_rq_lock - lock this runqueue and disable interrupts.
526 static inline struct rq *this_rq_lock(void)
533 spin_lock(&rq->lock);
539 * CPU frequency is/was unstable - start new by setting prev_clock_raw:
541 void sched_clock_unstable_event(void)
546 rq = task_rq_lock(current, &flags);
547 rq->prev_clock_raw = sched_clock();
548 rq->clock_unstable_events++;
549 task_rq_unlock(rq, &flags);
553 * resched_task - mark a task 'to be rescheduled now'.
555 * On UP this means the setting of the need_resched flag, on SMP it
556 * might also involve a cross-CPU call to trigger the scheduler on
561 #ifndef tsk_is_polling
562 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
565 static void resched_task(struct task_struct *p)
569 assert_spin_locked(&task_rq(p)->lock);
571 if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED)))
574 set_tsk_thread_flag(p, TIF_NEED_RESCHED);
577 if (cpu == smp_processor_id())
580 /* NEED_RESCHED must be visible before we test polling */
582 if (!tsk_is_polling(p))
583 smp_send_reschedule(cpu);
586 static void resched_cpu(int cpu)
588 struct rq *rq = cpu_rq(cpu);
591 if (!spin_trylock_irqsave(&rq->lock, flags))
593 resched_task(cpu_curr(cpu));
594 spin_unlock_irqrestore(&rq->lock, flags);
597 static inline void resched_task(struct task_struct *p)
599 assert_spin_locked(&task_rq(p)->lock);
600 set_tsk_need_resched(p);
604 static u64 div64_likely32(u64 divident, unsigned long divisor)
606 #if BITS_PER_LONG == 32
607 if (likely(divident <= 0xffffffffULL))
608 return (u32)divident / divisor;
609 do_div(divident, divisor);
613 return divident / divisor;
617 #if BITS_PER_LONG == 32
618 # define WMULT_CONST (~0UL)
620 # define WMULT_CONST (1UL << 32)
623 #define WMULT_SHIFT 32
625 static inline unsigned long
626 calc_delta_mine(unsigned long delta_exec, unsigned long weight,
627 struct load_weight *lw)
631 if (unlikely(!lw->inv_weight))
632 lw->inv_weight = WMULT_CONST / lw->weight;
634 tmp = (u64)delta_exec * weight;
636 * Check whether we'd overflow the 64-bit multiplication:
638 if (unlikely(tmp > WMULT_CONST)) {
639 tmp = ((tmp >> WMULT_SHIFT/2) * lw->inv_weight)
642 tmp = (tmp * lw->inv_weight) >> WMULT_SHIFT;
645 return (unsigned long)min(tmp, (u64)sysctl_sched_runtime_limit);
648 static inline unsigned long
649 calc_delta_fair(unsigned long delta_exec, struct load_weight *lw)
651 return calc_delta_mine(delta_exec, NICE_0_LOAD, lw);
654 static void update_load_add(struct load_weight *lw, unsigned long inc)
660 static void update_load_sub(struct load_weight *lw, unsigned long dec)
666 static void __update_curr_load(struct rq *rq, struct load_stat *ls)
668 if (rq->curr != rq->idle && ls->load.weight) {
669 ls->delta_exec += ls->delta_stat;
670 ls->delta_fair += calc_delta_fair(ls->delta_stat, &ls->load);
676 * Update delta_exec, delta_fair fields for rq.
678 * delta_fair clock advances at a rate inversely proportional to
679 * total load (rq->ls.load.weight) on the runqueue, while
680 * delta_exec advances at the same rate as wall-clock (provided
683 * delta_exec / delta_fair is a measure of the (smoothened) load on this
684 * runqueue over any given interval. This (smoothened) load is used
685 * during load balance.
687 * This function is called /before/ updating rq->ls.load
688 * and when switching tasks.
690 static void update_curr_load(struct rq *rq, u64 now)
692 struct load_stat *ls = &rq->ls;
695 start = ls->load_update_start;
696 ls->load_update_start = now;
697 ls->delta_stat += now - start;
699 * Stagger updates to ls->delta_fair. Very frequent updates
702 if (ls->delta_stat >= sysctl_sched_stat_granularity)
703 __update_curr_load(rq, ls);
707 * To aid in avoiding the subversion of "niceness" due to uneven distribution
708 * of tasks with abnormal "nice" values across CPUs the contribution that
709 * each task makes to its run queue's load is weighted according to its
710 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
711 * scaled version of the new time slice allocation that they receive on time
716 * Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
717 * If static_prio_timeslice() is ever changed to break this assumption then
718 * this code will need modification
720 #define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
721 #define load_weight(lp) \
722 (((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
723 #define PRIO_TO_LOAD_WEIGHT(prio) \
724 load_weight(static_prio_timeslice(prio))
725 #define RTPRIO_TO_LOAD_WEIGHT(rp) \
726 (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + load_weight(rp))
728 #define WEIGHT_IDLEPRIO 2
729 #define WMULT_IDLEPRIO (1 << 31)
732 * Nice levels are multiplicative, with a gentle 10% change for every
733 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
734 * nice 1, it will get ~10% less CPU time than another CPU-bound task
735 * that remained on nice 0.
737 * The "10% effect" is relative and cumulative: from _any_ nice level,
738 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
739 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
740 * If a task goes up by ~10% and another task goes down by ~10% then
741 * the relative distance between them is ~25%.)
743 static const int prio_to_weight[40] = {
744 /* -20 */ 88818, 71054, 56843, 45475, 36380, 29104, 23283, 18626, 14901, 11921,
745 /* -10 */ 9537, 7629, 6103, 4883, 3906, 3125, 2500, 2000, 1600, 1280,
746 /* 0 */ NICE_0_LOAD /* 1024 */,
747 /* 1 */ 819, 655, 524, 419, 336, 268, 215, 172, 137,
748 /* 10 */ 110, 87, 70, 56, 45, 36, 29, 23, 18, 15,
752 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
754 * In cases where the weight does not change often, we can use the
755 * precalculated inverse to speed up arithmetics by turning divisions
756 * into multiplications:
758 static const u32 prio_to_wmult[40] = {
759 /* -20 */ 48356, 60446, 75558, 94446, 118058,
760 /* -15 */ 147573, 184467, 230589, 288233, 360285,
761 /* -10 */ 450347, 562979, 703746, 879575, 1099582,
762 /* -5 */ 1374389, 1717986, 2147483, 2684354, 3355443,
763 /* 0 */ 4194304, 5244160, 6557201, 8196502, 10250518,
764 /* 5 */ 12782640, 16025997, 19976592, 24970740, 31350126,
765 /* 10 */ 39045157, 49367440, 61356675, 76695844, 95443717,
766 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
770 inc_load(struct rq *rq, const struct task_struct *p, u64 now)
772 update_curr_load(rq, now);
773 update_load_add(&rq->ls.load, p->se.load.weight);
777 dec_load(struct rq *rq, const struct task_struct *p, u64 now)
779 update_curr_load(rq, now);
780 update_load_sub(&rq->ls.load, p->se.load.weight);
783 static inline void inc_nr_running(struct task_struct *p, struct rq *rq, u64 now)
786 inc_load(rq, p, now);
789 static inline void dec_nr_running(struct task_struct *p, struct rq *rq, u64 now)
792 dec_load(rq, p, now);
795 static void activate_task(struct rq *rq, struct task_struct *p, int wakeup);
798 * runqueue iterator, to support SMP load-balancing between different
799 * scheduling classes, without having to expose their internal data
800 * structures to the load-balancing proper:
804 struct task_struct *(*start)(void *);
805 struct task_struct *(*next)(void *);
808 static int balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
809 unsigned long max_nr_move, unsigned long max_load_move,
810 struct sched_domain *sd, enum cpu_idle_type idle,
811 int *all_pinned, unsigned long *load_moved,
812 int this_best_prio, int best_prio, int best_prio_seen,
813 struct rq_iterator *iterator);
815 #include "sched_stats.h"
816 #include "sched_rt.c"
817 #include "sched_fair.c"
818 #include "sched_idletask.c"
819 #ifdef CONFIG_SCHED_DEBUG
820 # include "sched_debug.c"
823 #define sched_class_highest (&rt_sched_class)
825 static void set_load_weight(struct task_struct *p)
827 task_rq(p)->cfs.wait_runtime -= p->se.wait_runtime;
828 p->se.wait_runtime = 0;
830 if (task_has_rt_policy(p)) {
831 p->se.load.weight = prio_to_weight[0] * 2;
832 p->se.load.inv_weight = prio_to_wmult[0] >> 1;
837 * SCHED_IDLE tasks get minimal weight:
839 if (p->policy == SCHED_IDLE) {
840 p->se.load.weight = WEIGHT_IDLEPRIO;
841 p->se.load.inv_weight = WMULT_IDLEPRIO;
845 p->se.load.weight = prio_to_weight[p->static_prio - MAX_RT_PRIO];
846 p->se.load.inv_weight = prio_to_wmult[p->static_prio - MAX_RT_PRIO];
850 enqueue_task(struct rq *rq, struct task_struct *p, int wakeup, u64 now)
852 sched_info_queued(p);
853 p->sched_class->enqueue_task(rq, p, wakeup, now);
858 dequeue_task(struct rq *rq, struct task_struct *p, int sleep, u64 now)
860 p->sched_class->dequeue_task(rq, p, sleep, now);
865 * __normal_prio - return the priority that is based on the static prio
867 static inline int __normal_prio(struct task_struct *p)
869 return p->static_prio;
873 * Calculate the expected normal priority: i.e. priority
874 * without taking RT-inheritance into account. Might be
875 * boosted by interactivity modifiers. Changes upon fork,
876 * setprio syscalls, and whenever the interactivity
877 * estimator recalculates.
879 static inline int normal_prio(struct task_struct *p)
883 if (task_has_rt_policy(p))
884 prio = MAX_RT_PRIO-1 - p->rt_priority;
886 prio = __normal_prio(p);
891 * Calculate the current priority, i.e. the priority
892 * taken into account by the scheduler. This value might
893 * be boosted by RT tasks, or might be boosted by
894 * interactivity modifiers. Will be RT if the task got
895 * RT-boosted. If not then it returns p->normal_prio.
897 static int effective_prio(struct task_struct *p)
899 p->normal_prio = normal_prio(p);
901 * If we are RT tasks or we were boosted to RT priority,
902 * keep the priority unchanged. Otherwise, update priority
903 * to the normal priority:
905 if (!rt_prio(p->prio))
906 return p->normal_prio;
911 * activate_task - move a task to the runqueue.
913 static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
915 u64 now = rq_clock(rq);
917 if (p->state == TASK_UNINTERRUPTIBLE)
918 rq->nr_uninterruptible--;
920 enqueue_task(rq, p, wakeup, now);
921 inc_nr_running(p, rq, now);
925 * activate_idle_task - move idle task to the _front_ of runqueue.
927 static inline void activate_idle_task(struct task_struct *p, struct rq *rq)
929 u64 now = rq_clock(rq);
931 if (p->state == TASK_UNINTERRUPTIBLE)
932 rq->nr_uninterruptible--;
934 enqueue_task(rq, p, 0, now);
935 inc_nr_running(p, rq, now);
939 * deactivate_task - remove a task from the runqueue.
941 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
943 u64 now = rq_clock(rq);
945 if (p->state == TASK_UNINTERRUPTIBLE)
946 rq->nr_uninterruptible++;
948 dequeue_task(rq, p, sleep, now);
949 dec_nr_running(p, rq, now);
953 * task_curr - is this task currently executing on a CPU?
954 * @p: the task in question.
956 inline int task_curr(const struct task_struct *p)
958 return cpu_curr(task_cpu(p)) == p;
961 /* Used instead of source_load when we know the type == 0 */
962 unsigned long weighted_cpuload(const int cpu)
964 return cpu_rq(cpu)->ls.load.weight;
967 static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
970 task_thread_info(p)->cpu = cpu;
977 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
979 int old_cpu = task_cpu(p);
980 struct rq *old_rq = cpu_rq(old_cpu), *new_rq = cpu_rq(new_cpu);
981 u64 clock_offset, fair_clock_offset;
983 clock_offset = old_rq->clock - new_rq->clock;
984 fair_clock_offset = old_rq->cfs.fair_clock -
985 new_rq->cfs.fair_clock;
986 if (p->se.wait_start)
987 p->se.wait_start -= clock_offset;
988 if (p->se.wait_start_fair)
989 p->se.wait_start_fair -= fair_clock_offset;
990 if (p->se.sleep_start)
991 p->se.sleep_start -= clock_offset;
992 if (p->se.block_start)
993 p->se.block_start -= clock_offset;
994 if (p->se.sleep_start_fair)
995 p->se.sleep_start_fair -= fair_clock_offset;
997 __set_task_cpu(p, new_cpu);
1000 struct migration_req {
1001 struct list_head list;
1003 struct task_struct *task;
1006 struct completion done;
1010 * The task's runqueue lock must be held.
1011 * Returns true if you have to wait for migration thread.
1014 migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
1016 struct rq *rq = task_rq(p);
1019 * If the task is not on a runqueue (and not running), then
1020 * it is sufficient to simply update the task's cpu field.
1022 if (!p->se.on_rq && !task_running(rq, p)) {
1023 set_task_cpu(p, dest_cpu);
1027 init_completion(&req->done);
1029 req->dest_cpu = dest_cpu;
1030 list_add(&req->list, &rq->migration_queue);
1036 * wait_task_inactive - wait for a thread to unschedule.
1038 * The caller must ensure that the task *will* unschedule sometime soon,
1039 * else this function might spin for a *long* time. This function can't
1040 * be called with interrupts off, or it may introduce deadlock with
1041 * smp_call_function() if an IPI is sent by the same process we are
1042 * waiting to become inactive.
1044 void wait_task_inactive(struct task_struct *p)
1046 unsigned long flags;
1052 * We do the initial early heuristics without holding
1053 * any task-queue locks at all. We'll only try to get
1054 * the runqueue lock when things look like they will
1060 * If the task is actively running on another CPU
1061 * still, just relax and busy-wait without holding
1064 * NOTE! Since we don't hold any locks, it's not
1065 * even sure that "rq" stays as the right runqueue!
1066 * But we don't care, since "task_running()" will
1067 * return false if the runqueue has changed and p
1068 * is actually now running somewhere else!
1070 while (task_running(rq, p))
1074 * Ok, time to look more closely! We need the rq
1075 * lock now, to be *sure*. If we're wrong, we'll
1076 * just go back and repeat.
1078 rq = task_rq_lock(p, &flags);
1079 running = task_running(rq, p);
1080 on_rq = p->se.on_rq;
1081 task_rq_unlock(rq, &flags);
1084 * Was it really running after all now that we
1085 * checked with the proper locks actually held?
1087 * Oops. Go back and try again..
1089 if (unlikely(running)) {
1095 * It's not enough that it's not actively running,
1096 * it must be off the runqueue _entirely_, and not
1099 * So if it wa still runnable (but just not actively
1100 * running right now), it's preempted, and we should
1101 * yield - it could be a while.
1103 if (unlikely(on_rq)) {
1109 * Ahh, all good. It wasn't running, and it wasn't
1110 * runnable, which means that it will never become
1111 * running in the future either. We're all done!
1116 * kick_process - kick a running thread to enter/exit the kernel
1117 * @p: the to-be-kicked thread
1119 * Cause a process which is running on another CPU to enter
1120 * kernel-mode, without any delay. (to get signals handled.)
1122 * NOTE: this function doesnt have to take the runqueue lock,
1123 * because all it wants to ensure is that the remote task enters
1124 * the kernel. If the IPI races and the task has been migrated
1125 * to another CPU then no harm is done and the purpose has been
1128 void kick_process(struct task_struct *p)
1134 if ((cpu != smp_processor_id()) && task_curr(p))
1135 smp_send_reschedule(cpu);
1140 * Return a low guess at the load of a migration-source cpu weighted
1141 * according to the scheduling class and "nice" value.
1143 * We want to under-estimate the load of migration sources, to
1144 * balance conservatively.
1146 static inline unsigned long source_load(int cpu, int type)
1148 struct rq *rq = cpu_rq(cpu);
1149 unsigned long total = weighted_cpuload(cpu);
1154 return min(rq->cpu_load[type-1], total);
1158 * Return a high guess at the load of a migration-target cpu weighted
1159 * according to the scheduling class and "nice" value.
1161 static inline unsigned long target_load(int cpu, int type)
1163 struct rq *rq = cpu_rq(cpu);
1164 unsigned long total = weighted_cpuload(cpu);
1169 return max(rq->cpu_load[type-1], total);
1173 * Return the average load per task on the cpu's run queue
1175 static inline unsigned long cpu_avg_load_per_task(int cpu)
1177 struct rq *rq = cpu_rq(cpu);
1178 unsigned long total = weighted_cpuload(cpu);
1179 unsigned long n = rq->nr_running;
1181 return n ? total / n : SCHED_LOAD_SCALE;
1185 * find_idlest_group finds and returns the least busy CPU group within the
1188 static struct sched_group *
1189 find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
1191 struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
1192 unsigned long min_load = ULONG_MAX, this_load = 0;
1193 int load_idx = sd->forkexec_idx;
1194 int imbalance = 100 + (sd->imbalance_pct-100)/2;
1197 unsigned long load, avg_load;
1201 /* Skip over this group if it has no CPUs allowed */
1202 if (!cpus_intersects(group->cpumask, p->cpus_allowed))
1205 local_group = cpu_isset(this_cpu, group->cpumask);
1207 /* Tally up the load of all CPUs in the group */
1210 for_each_cpu_mask(i, group->cpumask) {
1211 /* Bias balancing toward cpus of our domain */
1213 load = source_load(i, load_idx);
1215 load = target_load(i, load_idx);
1220 /* Adjust by relative CPU power of the group */
1221 avg_load = sg_div_cpu_power(group,
1222 avg_load * SCHED_LOAD_SCALE);
1225 this_load = avg_load;
1227 } else if (avg_load < min_load) {
1228 min_load = avg_load;
1232 group = group->next;
1233 } while (group != sd->groups);
1235 if (!idlest || 100*this_load < imbalance*min_load)
1241 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1244 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
1247 unsigned long load, min_load = ULONG_MAX;
1251 /* Traverse only the allowed CPUs */
1252 cpus_and(tmp, group->cpumask, p->cpus_allowed);
1254 for_each_cpu_mask(i, tmp) {
1255 load = weighted_cpuload(i);
1257 if (load < min_load || (load == min_load && i == this_cpu)) {
1267 * sched_balance_self: balance the current task (running on cpu) in domains
1268 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1271 * Balance, ie. select the least loaded group.
1273 * Returns the target CPU number, or the same CPU if no balancing is needed.
1275 * preempt must be disabled.
1277 static int sched_balance_self(int cpu, int flag)
1279 struct task_struct *t = current;
1280 struct sched_domain *tmp, *sd = NULL;
1282 for_each_domain(cpu, tmp) {
1284 * If power savings logic is enabled for a domain, stop there.
1286 if (tmp->flags & SD_POWERSAVINGS_BALANCE)
1288 if (tmp->flags & flag)
1294 struct sched_group *group;
1295 int new_cpu, weight;
1297 if (!(sd->flags & flag)) {
1303 group = find_idlest_group(sd, t, cpu);
1309 new_cpu = find_idlest_cpu(group, t, cpu);
1310 if (new_cpu == -1 || new_cpu == cpu) {
1311 /* Now try balancing at a lower domain level of cpu */
1316 /* Now try balancing at a lower domain level of new_cpu */
1319 weight = cpus_weight(span);
1320 for_each_domain(cpu, tmp) {
1321 if (weight <= cpus_weight(tmp->span))
1323 if (tmp->flags & flag)
1326 /* while loop will break here if sd == NULL */
1332 #endif /* CONFIG_SMP */
1335 * wake_idle() will wake a task on an idle cpu if task->cpu is
1336 * not idle and an idle cpu is available. The span of cpus to
1337 * search starts with cpus closest then further out as needed,
1338 * so we always favor a closer, idle cpu.
1340 * Returns the CPU we should wake onto.
1342 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1343 static int wake_idle(int cpu, struct task_struct *p)
1346 struct sched_domain *sd;
1350 * If it is idle, then it is the best cpu to run this task.
1352 * This cpu is also the best, if it has more than one task already.
1353 * Siblings must be also busy(in most cases) as they didn't already
1354 * pickup the extra load from this cpu and hence we need not check
1355 * sibling runqueue info. This will avoid the checks and cache miss
1356 * penalities associated with that.
1358 if (idle_cpu(cpu) || cpu_rq(cpu)->nr_running > 1)
1361 for_each_domain(cpu, sd) {
1362 if (sd->flags & SD_WAKE_IDLE) {
1363 cpus_and(tmp, sd->span, p->cpus_allowed);
1364 for_each_cpu_mask(i, tmp) {
1375 static inline int wake_idle(int cpu, struct task_struct *p)
1382 * try_to_wake_up - wake up a thread
1383 * @p: the to-be-woken-up thread
1384 * @state: the mask of task states that can be woken
1385 * @sync: do a synchronous wakeup?
1387 * Put it on the run-queue if it's not already there. The "current"
1388 * thread is always on the run-queue (except when the actual
1389 * re-schedule is in progress), and as such you're allowed to do
1390 * the simpler "current->state = TASK_RUNNING" to mark yourself
1391 * runnable without the overhead of this.
1393 * returns failure only if the task is already active.
1395 static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
1397 int cpu, this_cpu, success = 0;
1398 unsigned long flags;
1402 struct sched_domain *sd, *this_sd = NULL;
1403 unsigned long load, this_load;
1407 rq = task_rq_lock(p, &flags);
1408 old_state = p->state;
1409 if (!(old_state & state))
1416 this_cpu = smp_processor_id();
1419 if (unlikely(task_running(rq, p)))
1424 schedstat_inc(rq, ttwu_cnt);
1425 if (cpu == this_cpu) {
1426 schedstat_inc(rq, ttwu_local);
1430 for_each_domain(this_cpu, sd) {
1431 if (cpu_isset(cpu, sd->span)) {
1432 schedstat_inc(sd, ttwu_wake_remote);
1438 if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
1442 * Check for affine wakeup and passive balancing possibilities.
1445 int idx = this_sd->wake_idx;
1446 unsigned int imbalance;
1448 imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
1450 load = source_load(cpu, idx);
1451 this_load = target_load(this_cpu, idx);
1453 new_cpu = this_cpu; /* Wake to this CPU if we can */
1455 if (this_sd->flags & SD_WAKE_AFFINE) {
1456 unsigned long tl = this_load;
1457 unsigned long tl_per_task;
1459 tl_per_task = cpu_avg_load_per_task(this_cpu);
1462 * If sync wakeup then subtract the (maximum possible)
1463 * effect of the currently running task from the load
1464 * of the current CPU:
1467 tl -= current->se.load.weight;
1470 tl + target_load(cpu, idx) <= tl_per_task) ||
1471 100*(tl + p->se.load.weight) <= imbalance*load) {
1473 * This domain has SD_WAKE_AFFINE and
1474 * p is cache cold in this domain, and
1475 * there is no bad imbalance.
1477 schedstat_inc(this_sd, ttwu_move_affine);
1483 * Start passive balancing when half the imbalance_pct
1486 if (this_sd->flags & SD_WAKE_BALANCE) {
1487 if (imbalance*this_load <= 100*load) {
1488 schedstat_inc(this_sd, ttwu_move_balance);
1494 new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
1496 new_cpu = wake_idle(new_cpu, p);
1497 if (new_cpu != cpu) {
1498 set_task_cpu(p, new_cpu);
1499 task_rq_unlock(rq, &flags);
1500 /* might preempt at this point */
1501 rq = task_rq_lock(p, &flags);
1502 old_state = p->state;
1503 if (!(old_state & state))
1508 this_cpu = smp_processor_id();
1513 #endif /* CONFIG_SMP */
1514 activate_task(rq, p, 1);
1516 * Sync wakeups (i.e. those types of wakeups where the waker
1517 * has indicated that it will leave the CPU in short order)
1518 * don't trigger a preemption, if the woken up task will run on
1519 * this cpu. (in this case the 'I will reschedule' promise of
1520 * the waker guarantees that the freshly woken up task is going
1521 * to be considered on this CPU.)
1523 if (!sync || cpu != this_cpu)
1524 check_preempt_curr(rq, p);
1528 p->state = TASK_RUNNING;
1530 task_rq_unlock(rq, &flags);
1535 int fastcall wake_up_process(struct task_struct *p)
1537 return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
1538 TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
1540 EXPORT_SYMBOL(wake_up_process);
1542 int fastcall wake_up_state(struct task_struct *p, unsigned int state)
1544 return try_to_wake_up(p, state, 0);
1548 * Perform scheduler related setup for a newly forked process p.
1549 * p is forked by current.
1551 * __sched_fork() is basic setup used by init_idle() too:
1553 static void __sched_fork(struct task_struct *p)
1555 p->se.wait_start_fair = 0;
1556 p->se.wait_start = 0;
1557 p->se.exec_start = 0;
1558 p->se.sum_exec_runtime = 0;
1559 p->se.delta_exec = 0;
1560 p->se.delta_fair_run = 0;
1561 p->se.delta_fair_sleep = 0;
1562 p->se.wait_runtime = 0;
1563 p->se.sum_wait_runtime = 0;
1564 p->se.sum_sleep_runtime = 0;
1565 p->se.sleep_start = 0;
1566 p->se.sleep_start_fair = 0;
1567 p->se.block_start = 0;
1568 p->se.sleep_max = 0;
1569 p->se.block_max = 0;
1572 p->se.wait_runtime_overruns = 0;
1573 p->se.wait_runtime_underruns = 0;
1575 INIT_LIST_HEAD(&p->run_list);
1579 * We mark the process as running here, but have not actually
1580 * inserted it onto the runqueue yet. This guarantees that
1581 * nobody will actually run it, and a signal or other external
1582 * event cannot wake it up and insert it on the runqueue either.
1584 p->state = TASK_RUNNING;
1588 * fork()/clone()-time setup:
1590 void sched_fork(struct task_struct *p, int clone_flags)
1592 int cpu = get_cpu();
1597 cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
1599 __set_task_cpu(p, cpu);
1602 * Make sure we do not leak PI boosting priority to the child:
1604 p->prio = current->normal_prio;
1606 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1607 if (likely(sched_info_on()))
1608 memset(&p->sched_info, 0, sizeof(p->sched_info));
1610 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1613 #ifdef CONFIG_PREEMPT
1614 /* Want to start with kernel preemption disabled. */
1615 task_thread_info(p)->preempt_count = 1;
1621 * After fork, child runs first. (default) If set to 0 then
1622 * parent will (try to) run first.
1624 unsigned int __read_mostly sysctl_sched_child_runs_first = 1;
1627 * wake_up_new_task - wake up a newly created task for the first time.
1629 * This function will do some initial scheduler statistics housekeeping
1630 * that must be done for every newly created context, then puts the task
1631 * on the runqueue and wakes it.
1633 void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
1635 unsigned long flags;
1639 rq = task_rq_lock(p, &flags);
1640 BUG_ON(p->state != TASK_RUNNING);
1641 this_cpu = smp_processor_id(); /* parent's CPU */
1643 p->prio = effective_prio(p);
1645 if (!sysctl_sched_child_runs_first || (clone_flags & CLONE_VM) ||
1646 task_cpu(p) != this_cpu || !current->se.on_rq) {
1647 activate_task(rq, p, 0);
1650 * Let the scheduling class do new task startup
1651 * management (if any):
1653 p->sched_class->task_new(rq, p);
1655 check_preempt_curr(rq, p);
1656 task_rq_unlock(rq, &flags);
1660 * prepare_task_switch - prepare to switch tasks
1661 * @rq: the runqueue preparing to switch
1662 * @next: the task we are going to switch to.
1664 * This is called with the rq lock held and interrupts off. It must
1665 * be paired with a subsequent finish_task_switch after the context
1668 * prepare_task_switch sets up locking and calls architecture specific
1671 static inline void prepare_task_switch(struct rq *rq, struct task_struct *next)
1673 prepare_lock_switch(rq, next);
1674 prepare_arch_switch(next);
1678 * finish_task_switch - clean up after a task-switch
1679 * @rq: runqueue associated with task-switch
1680 * @prev: the thread we just switched away from.
1682 * finish_task_switch must be called after the context switch, paired
1683 * with a prepare_task_switch call before the context switch.
1684 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1685 * and do any other architecture-specific cleanup actions.
1687 * Note that we may have delayed dropping an mm in context_switch(). If
1688 * so, we finish that here outside of the runqueue lock. (Doing it
1689 * with the lock held can cause deadlocks; see schedule() for
1692 static inline void finish_task_switch(struct rq *rq, struct task_struct *prev)
1693 __releases(rq->lock)
1695 struct mm_struct *mm = rq->prev_mm;
1701 * A task struct has one reference for the use as "current".
1702 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1703 * schedule one last time. The schedule call will never return, and
1704 * the scheduled task must drop that reference.
1705 * The test for TASK_DEAD must occur while the runqueue locks are
1706 * still held, otherwise prev could be scheduled on another cpu, die
1707 * there before we look at prev->state, and then the reference would
1709 * Manfred Spraul <manfred@colorfullife.com>
1711 prev_state = prev->state;
1712 finish_arch_switch(prev);
1713 finish_lock_switch(rq, prev);
1716 if (unlikely(prev_state == TASK_DEAD)) {
1718 * Remove function-return probe instances associated with this
1719 * task and put them back on the free list.
1721 kprobe_flush_task(prev);
1722 put_task_struct(prev);
1727 * schedule_tail - first thing a freshly forked thread must call.
1728 * @prev: the thread we just switched away from.
1730 asmlinkage void schedule_tail(struct task_struct *prev)
1731 __releases(rq->lock)
1733 struct rq *rq = this_rq();
1735 finish_task_switch(rq, prev);
1736 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1737 /* In this case, finish_task_switch does not reenable preemption */
1740 if (current->set_child_tid)
1741 put_user(current->pid, current->set_child_tid);
1745 * context_switch - switch to the new MM and the new
1746 * thread's register state.
1749 context_switch(struct rq *rq, struct task_struct *prev,
1750 struct task_struct *next)
1752 struct mm_struct *mm, *oldmm;
1754 prepare_task_switch(rq, next);
1756 oldmm = prev->active_mm;
1758 * For paravirt, this is coupled with an exit in switch_to to
1759 * combine the page table reload and the switch backend into
1762 arch_enter_lazy_cpu_mode();
1764 if (unlikely(!mm)) {
1765 next->active_mm = oldmm;
1766 atomic_inc(&oldmm->mm_count);
1767 enter_lazy_tlb(oldmm, next);
1769 switch_mm(oldmm, mm, next);
1771 if (unlikely(!prev->mm)) {
1772 prev->active_mm = NULL;
1773 rq->prev_mm = oldmm;
1776 * Since the runqueue lock will be released by the next
1777 * task (which is an invalid locking op but in the case
1778 * of the scheduler it's an obvious special-case), so we
1779 * do an early lockdep release here:
1781 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1782 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
1785 /* Here we just switch the register state and the stack. */
1786 switch_to(prev, next, prev);
1790 * this_rq must be evaluated again because prev may have moved
1791 * CPUs since it called schedule(), thus the 'rq' on its stack
1792 * frame will be invalid.
1794 finish_task_switch(this_rq(), prev);
1798 * nr_running, nr_uninterruptible and nr_context_switches:
1800 * externally visible scheduler statistics: current number of runnable
1801 * threads, current number of uninterruptible-sleeping threads, total
1802 * number of context switches performed since bootup.
1804 unsigned long nr_running(void)
1806 unsigned long i, sum = 0;
1808 for_each_online_cpu(i)
1809 sum += cpu_rq(i)->nr_running;
1814 unsigned long nr_uninterruptible(void)
1816 unsigned long i, sum = 0;
1818 for_each_possible_cpu(i)
1819 sum += cpu_rq(i)->nr_uninterruptible;
1822 * Since we read the counters lockless, it might be slightly
1823 * inaccurate. Do not allow it to go below zero though:
1825 if (unlikely((long)sum < 0))
1831 unsigned long long nr_context_switches(void)
1834 unsigned long long sum = 0;
1836 for_each_possible_cpu(i)
1837 sum += cpu_rq(i)->nr_switches;
1842 unsigned long nr_iowait(void)
1844 unsigned long i, sum = 0;
1846 for_each_possible_cpu(i)
1847 sum += atomic_read(&cpu_rq(i)->nr_iowait);
1852 unsigned long nr_active(void)
1854 unsigned long i, running = 0, uninterruptible = 0;
1856 for_each_online_cpu(i) {
1857 running += cpu_rq(i)->nr_running;
1858 uninterruptible += cpu_rq(i)->nr_uninterruptible;
1861 if (unlikely((long)uninterruptible < 0))
1862 uninterruptible = 0;
1864 return running + uninterruptible;
1868 * Update rq->cpu_load[] statistics. This function is usually called every
1869 * scheduler tick (TICK_NSEC).
1871 static void update_cpu_load(struct rq *this_rq)
1873 u64 fair_delta64, exec_delta64, idle_delta64, sample_interval64, tmp64;
1874 unsigned long total_load = this_rq->ls.load.weight;
1875 unsigned long this_load = total_load;
1876 struct load_stat *ls = &this_rq->ls;
1877 u64 now = __rq_clock(this_rq);
1880 this_rq->nr_load_updates++;
1881 if (unlikely(!(sysctl_sched_features & SCHED_FEAT_PRECISE_CPU_LOAD)))
1884 /* Update delta_fair/delta_exec fields first */
1885 update_curr_load(this_rq, now);
1887 fair_delta64 = ls->delta_fair + 1;
1890 exec_delta64 = ls->delta_exec + 1;
1893 sample_interval64 = now - ls->load_update_last;
1894 ls->load_update_last = now;
1896 if ((s64)sample_interval64 < (s64)TICK_NSEC)
1897 sample_interval64 = TICK_NSEC;
1899 if (exec_delta64 > sample_interval64)
1900 exec_delta64 = sample_interval64;
1902 idle_delta64 = sample_interval64 - exec_delta64;
1904 tmp64 = div64_64(SCHED_LOAD_SCALE * exec_delta64, fair_delta64);
1905 tmp64 = div64_64(tmp64 * exec_delta64, sample_interval64);
1907 this_load = (unsigned long)tmp64;
1911 /* Update our load: */
1912 for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
1913 unsigned long old_load, new_load;
1915 /* scale is effectively 1 << i now, and >> i divides by scale */
1917 old_load = this_rq->cpu_load[i];
1918 new_load = this_load;
1920 this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
1927 * double_rq_lock - safely lock two runqueues
1929 * Note this does not disable interrupts like task_rq_lock,
1930 * you need to do so manually before calling.
1932 static void double_rq_lock(struct rq *rq1, struct rq *rq2)
1933 __acquires(rq1->lock)
1934 __acquires(rq2->lock)
1936 BUG_ON(!irqs_disabled());
1938 spin_lock(&rq1->lock);
1939 __acquire(rq2->lock); /* Fake it out ;) */
1942 spin_lock(&rq1->lock);
1943 spin_lock(&rq2->lock);
1945 spin_lock(&rq2->lock);
1946 spin_lock(&rq1->lock);
1952 * double_rq_unlock - safely unlock two runqueues
1954 * Note this does not restore interrupts like task_rq_unlock,
1955 * you need to do so manually after calling.
1957 static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
1958 __releases(rq1->lock)
1959 __releases(rq2->lock)
1961 spin_unlock(&rq1->lock);
1963 spin_unlock(&rq2->lock);
1965 __release(rq2->lock);
1969 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1971 static void double_lock_balance(struct rq *this_rq, struct rq *busiest)
1972 __releases(this_rq->lock)
1973 __acquires(busiest->lock)
1974 __acquires(this_rq->lock)
1976 if (unlikely(!irqs_disabled())) {
1977 /* printk() doesn't work good under rq->lock */
1978 spin_unlock(&this_rq->lock);
1981 if (unlikely(!spin_trylock(&busiest->lock))) {
1982 if (busiest < this_rq) {
1983 spin_unlock(&this_rq->lock);
1984 spin_lock(&busiest->lock);
1985 spin_lock(&this_rq->lock);
1987 spin_lock(&busiest->lock);
1992 * If dest_cpu is allowed for this process, migrate the task to it.
1993 * This is accomplished by forcing the cpu_allowed mask to only
1994 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
1995 * the cpu_allowed mask is restored.
1997 static void sched_migrate_task(struct task_struct *p, int dest_cpu)
1999 struct migration_req req;
2000 unsigned long flags;
2003 rq = task_rq_lock(p, &flags);
2004 if (!cpu_isset(dest_cpu, p->cpus_allowed)
2005 || unlikely(cpu_is_offline(dest_cpu)))
2008 /* force the process onto the specified CPU */
2009 if (migrate_task(p, dest_cpu, &req)) {
2010 /* Need to wait for migration thread (might exit: take ref). */
2011 struct task_struct *mt = rq->migration_thread;
2013 get_task_struct(mt);
2014 task_rq_unlock(rq, &flags);
2015 wake_up_process(mt);
2016 put_task_struct(mt);
2017 wait_for_completion(&req.done);
2022 task_rq_unlock(rq, &flags);
2026 * sched_exec - execve() is a valuable balancing opportunity, because at
2027 * this point the task has the smallest effective memory and cache footprint.
2029 void sched_exec(void)
2031 int new_cpu, this_cpu = get_cpu();
2032 new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
2034 if (new_cpu != this_cpu)
2035 sched_migrate_task(current, new_cpu);
2039 * pull_task - move a task from a remote runqueue to the local runqueue.
2040 * Both runqueues must be locked.
2042 static void pull_task(struct rq *src_rq, struct task_struct *p,
2043 struct rq *this_rq, int this_cpu)
2045 deactivate_task(src_rq, p, 0);
2046 set_task_cpu(p, this_cpu);
2047 activate_task(this_rq, p, 0);
2049 * Note that idle threads have a prio of MAX_PRIO, for this test
2050 * to be always true for them.
2052 check_preempt_curr(this_rq, p);
2056 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2059 int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
2060 struct sched_domain *sd, enum cpu_idle_type idle,
2064 * We do not migrate tasks that are:
2065 * 1) running (obviously), or
2066 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2067 * 3) are cache-hot on their current CPU.
2069 if (!cpu_isset(this_cpu, p->cpus_allowed))
2073 if (task_running(rq, p))
2077 * Aggressive migration if too many balance attempts have failed:
2079 if (sd->nr_balance_failed > sd->cache_nice_tries)
2085 static int balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2086 unsigned long max_nr_move, unsigned long max_load_move,
2087 struct sched_domain *sd, enum cpu_idle_type idle,
2088 int *all_pinned, unsigned long *load_moved,
2089 int this_best_prio, int best_prio, int best_prio_seen,
2090 struct rq_iterator *iterator)
2092 int pulled = 0, pinned = 0, skip_for_load;
2093 struct task_struct *p;
2094 long rem_load_move = max_load_move;
2096 if (max_nr_move == 0 || max_load_move == 0)
2102 * Start the load-balancing iterator:
2104 p = iterator->start(iterator->arg);
2109 * To help distribute high priority tasks accross CPUs we don't
2110 * skip a task if it will be the highest priority task (i.e. smallest
2111 * prio value) on its new queue regardless of its load weight
2113 skip_for_load = (p->se.load.weight >> 1) > rem_load_move +
2114 SCHED_LOAD_SCALE_FUZZ;
2115 if (skip_for_load && p->prio < this_best_prio)
2116 skip_for_load = !best_prio_seen && p->prio == best_prio;
2117 if (skip_for_load ||
2118 !can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
2120 best_prio_seen |= p->prio == best_prio;
2121 p = iterator->next(iterator->arg);
2125 pull_task(busiest, p, this_rq, this_cpu);
2127 rem_load_move -= p->se.load.weight;
2130 * We only want to steal up to the prescribed number of tasks
2131 * and the prescribed amount of weighted load.
2133 if (pulled < max_nr_move && rem_load_move > 0) {
2134 if (p->prio < this_best_prio)
2135 this_best_prio = p->prio;
2136 p = iterator->next(iterator->arg);
2141 * Right now, this is the only place pull_task() is called,
2142 * so we can safely collect pull_task() stats here rather than
2143 * inside pull_task().
2145 schedstat_add(sd, lb_gained[idle], pulled);
2148 *all_pinned = pinned;
2149 *load_moved = max_load_move - rem_load_move;
2154 * move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
2155 * load from busiest to this_rq, as part of a balancing operation within
2156 * "domain". Returns the number of tasks moved.
2158 * Called with both runqueues locked.
2160 static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2161 unsigned long max_nr_move, unsigned long max_load_move,
2162 struct sched_domain *sd, enum cpu_idle_type idle,
2165 struct sched_class *class = sched_class_highest;
2166 unsigned long load_moved, total_nr_moved = 0, nr_moved;
2167 long rem_load_move = max_load_move;
2170 nr_moved = class->load_balance(this_rq, this_cpu, busiest,
2171 max_nr_move, (unsigned long)rem_load_move,
2172 sd, idle, all_pinned, &load_moved);
2173 total_nr_moved += nr_moved;
2174 max_nr_move -= nr_moved;
2175 rem_load_move -= load_moved;
2176 class = class->next;
2177 } while (class && max_nr_move && rem_load_move > 0);
2179 return total_nr_moved;
2183 * find_busiest_group finds and returns the busiest CPU group within the
2184 * domain. It calculates and returns the amount of weighted load which
2185 * should be moved to restore balance via the imbalance parameter.
2187 static struct sched_group *
2188 find_busiest_group(struct sched_domain *sd, int this_cpu,
2189 unsigned long *imbalance, enum cpu_idle_type idle,
2190 int *sd_idle, cpumask_t *cpus, int *balance)
2192 struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
2193 unsigned long max_load, avg_load, total_load, this_load, total_pwr;
2194 unsigned long max_pull;
2195 unsigned long busiest_load_per_task, busiest_nr_running;
2196 unsigned long this_load_per_task, this_nr_running;
2198 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2199 int power_savings_balance = 1;
2200 unsigned long leader_nr_running = 0, min_load_per_task = 0;
2201 unsigned long min_nr_running = ULONG_MAX;
2202 struct sched_group *group_min = NULL, *group_leader = NULL;
2205 max_load = this_load = total_load = total_pwr = 0;
2206 busiest_load_per_task = busiest_nr_running = 0;
2207 this_load_per_task = this_nr_running = 0;
2208 if (idle == CPU_NOT_IDLE)
2209 load_idx = sd->busy_idx;
2210 else if (idle == CPU_NEWLY_IDLE)
2211 load_idx = sd->newidle_idx;
2213 load_idx = sd->idle_idx;
2216 unsigned long load, group_capacity;
2219 unsigned int balance_cpu = -1, first_idle_cpu = 0;
2220 unsigned long sum_nr_running, sum_weighted_load;
2222 local_group = cpu_isset(this_cpu, group->cpumask);
2225 balance_cpu = first_cpu(group->cpumask);
2227 /* Tally up the load of all CPUs in the group */
2228 sum_weighted_load = sum_nr_running = avg_load = 0;
2230 for_each_cpu_mask(i, group->cpumask) {
2233 if (!cpu_isset(i, *cpus))
2238 if (*sd_idle && rq->nr_running)
2241 /* Bias balancing toward cpus of our domain */
2243 if (idle_cpu(i) && !first_idle_cpu) {
2248 load = target_load(i, load_idx);
2250 load = source_load(i, load_idx);
2253 sum_nr_running += rq->nr_running;
2254 sum_weighted_load += weighted_cpuload(i);
2258 * First idle cpu or the first cpu(busiest) in this sched group
2259 * is eligible for doing load balancing at this and above
2260 * domains. In the newly idle case, we will allow all the cpu's
2261 * to do the newly idle load balance.
2263 if (idle != CPU_NEWLY_IDLE && local_group &&
2264 balance_cpu != this_cpu && balance) {
2269 total_load += avg_load;
2270 total_pwr += group->__cpu_power;
2272 /* Adjust by relative CPU power of the group */
2273 avg_load = sg_div_cpu_power(group,
2274 avg_load * SCHED_LOAD_SCALE);
2276 group_capacity = group->__cpu_power / SCHED_LOAD_SCALE;
2279 this_load = avg_load;
2281 this_nr_running = sum_nr_running;
2282 this_load_per_task = sum_weighted_load;
2283 } else if (avg_load > max_load &&
2284 sum_nr_running > group_capacity) {
2285 max_load = avg_load;
2287 busiest_nr_running = sum_nr_running;
2288 busiest_load_per_task = sum_weighted_load;
2291 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2293 * Busy processors will not participate in power savings
2296 if (idle == CPU_NOT_IDLE ||
2297 !(sd->flags & SD_POWERSAVINGS_BALANCE))
2301 * If the local group is idle or completely loaded
2302 * no need to do power savings balance at this domain
2304 if (local_group && (this_nr_running >= group_capacity ||
2306 power_savings_balance = 0;
2309 * If a group is already running at full capacity or idle,
2310 * don't include that group in power savings calculations
2312 if (!power_savings_balance || sum_nr_running >= group_capacity
2317 * Calculate the group which has the least non-idle load.
2318 * This is the group from where we need to pick up the load
2321 if ((sum_nr_running < min_nr_running) ||
2322 (sum_nr_running == min_nr_running &&
2323 first_cpu(group->cpumask) <
2324 first_cpu(group_min->cpumask))) {
2326 min_nr_running = sum_nr_running;
2327 min_load_per_task = sum_weighted_load /
2332 * Calculate the group which is almost near its
2333 * capacity but still has some space to pick up some load
2334 * from other group and save more power
2336 if (sum_nr_running <= group_capacity - 1) {
2337 if (sum_nr_running > leader_nr_running ||
2338 (sum_nr_running == leader_nr_running &&
2339 first_cpu(group->cpumask) >
2340 first_cpu(group_leader->cpumask))) {
2341 group_leader = group;
2342 leader_nr_running = sum_nr_running;
2347 group = group->next;
2348 } while (group != sd->groups);
2350 if (!busiest || this_load >= max_load || busiest_nr_running == 0)
2353 avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
2355 if (this_load >= avg_load ||
2356 100*max_load <= sd->imbalance_pct*this_load)
2359 busiest_load_per_task /= busiest_nr_running;
2361 * We're trying to get all the cpus to the average_load, so we don't
2362 * want to push ourselves above the average load, nor do we wish to
2363 * reduce the max loaded cpu below the average load, as either of these
2364 * actions would just result in more rebalancing later, and ping-pong
2365 * tasks around. Thus we look for the minimum possible imbalance.
2366 * Negative imbalances (*we* are more loaded than anyone else) will
2367 * be counted as no imbalance for these purposes -- we can't fix that
2368 * by pulling tasks to us. Be careful of negative numbers as they'll
2369 * appear as very large values with unsigned longs.
2371 if (max_load <= busiest_load_per_task)
2375 * In the presence of smp nice balancing, certain scenarios can have
2376 * max load less than avg load(as we skip the groups at or below
2377 * its cpu_power, while calculating max_load..)
2379 if (max_load < avg_load) {
2381 goto small_imbalance;
2384 /* Don't want to pull so many tasks that a group would go idle */
2385 max_pull = min(max_load - avg_load, max_load - busiest_load_per_task);
2387 /* How much load to actually move to equalise the imbalance */
2388 *imbalance = min(max_pull * busiest->__cpu_power,
2389 (avg_load - this_load) * this->__cpu_power)
2393 * if *imbalance is less than the average load per runnable task
2394 * there is no gaurantee that any tasks will be moved so we'll have
2395 * a think about bumping its value to force at least one task to be
2398 if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task/2) {
2399 unsigned long tmp, pwr_now, pwr_move;
2403 pwr_move = pwr_now = 0;
2405 if (this_nr_running) {
2406 this_load_per_task /= this_nr_running;
2407 if (busiest_load_per_task > this_load_per_task)
2410 this_load_per_task = SCHED_LOAD_SCALE;
2412 if (max_load - this_load + SCHED_LOAD_SCALE_FUZZ >=
2413 busiest_load_per_task * imbn) {
2414 *imbalance = busiest_load_per_task;
2419 * OK, we don't have enough imbalance to justify moving tasks,
2420 * however we may be able to increase total CPU power used by
2424 pwr_now += busiest->__cpu_power *
2425 min(busiest_load_per_task, max_load);
2426 pwr_now += this->__cpu_power *
2427 min(this_load_per_task, this_load);
2428 pwr_now /= SCHED_LOAD_SCALE;
2430 /* Amount of load we'd subtract */
2431 tmp = sg_div_cpu_power(busiest,
2432 busiest_load_per_task * SCHED_LOAD_SCALE);
2434 pwr_move += busiest->__cpu_power *
2435 min(busiest_load_per_task, max_load - tmp);
2437 /* Amount of load we'd add */
2438 if (max_load * busiest->__cpu_power <
2439 busiest_load_per_task * SCHED_LOAD_SCALE)
2440 tmp = sg_div_cpu_power(this,
2441 max_load * busiest->__cpu_power);
2443 tmp = sg_div_cpu_power(this,
2444 busiest_load_per_task * SCHED_LOAD_SCALE);
2445 pwr_move += this->__cpu_power *
2446 min(this_load_per_task, this_load + tmp);
2447 pwr_move /= SCHED_LOAD_SCALE;
2449 /* Move if we gain throughput */
2450 if (pwr_move <= pwr_now)
2453 *imbalance = busiest_load_per_task;
2459 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2460 if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
2463 if (this == group_leader && group_leader != group_min) {
2464 *imbalance = min_load_per_task;
2474 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2477 find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
2478 unsigned long imbalance, cpumask_t *cpus)
2480 struct rq *busiest = NULL, *rq;
2481 unsigned long max_load = 0;
2484 for_each_cpu_mask(i, group->cpumask) {
2487 if (!cpu_isset(i, *cpus))
2491 wl = weighted_cpuload(i);
2493 if (rq->nr_running == 1 && wl > imbalance)
2496 if (wl > max_load) {
2506 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2507 * so long as it is large enough.
2509 #define MAX_PINNED_INTERVAL 512
2511 static inline unsigned long minus_1_or_zero(unsigned long n)
2513 return n > 0 ? n - 1 : 0;
2517 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2518 * tasks if there is an imbalance.
2520 static int load_balance(int this_cpu, struct rq *this_rq,
2521 struct sched_domain *sd, enum cpu_idle_type idle,
2524 int nr_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
2525 struct sched_group *group;
2526 unsigned long imbalance;
2528 cpumask_t cpus = CPU_MASK_ALL;
2529 unsigned long flags;
2532 * When power savings policy is enabled for the parent domain, idle
2533 * sibling can pick up load irrespective of busy siblings. In this case,
2534 * let the state of idle sibling percolate up as CPU_IDLE, instead of
2535 * portraying it as CPU_NOT_IDLE.
2537 if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
2538 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2541 schedstat_inc(sd, lb_cnt[idle]);
2544 group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
2551 schedstat_inc(sd, lb_nobusyg[idle]);
2555 busiest = find_busiest_queue(group, idle, imbalance, &cpus);
2557 schedstat_inc(sd, lb_nobusyq[idle]);
2561 BUG_ON(busiest == this_rq);
2563 schedstat_add(sd, lb_imbalance[idle], imbalance);
2566 if (busiest->nr_running > 1) {
2568 * Attempt to move tasks. If find_busiest_group has found
2569 * an imbalance but busiest->nr_running <= 1, the group is
2570 * still unbalanced. nr_moved simply stays zero, so it is
2571 * correctly treated as an imbalance.
2573 local_irq_save(flags);
2574 double_rq_lock(this_rq, busiest);
2575 nr_moved = move_tasks(this_rq, this_cpu, busiest,
2576 minus_1_or_zero(busiest->nr_running),
2577 imbalance, sd, idle, &all_pinned);
2578 double_rq_unlock(this_rq, busiest);
2579 local_irq_restore(flags);
2582 * some other cpu did the load balance for us.
2584 if (nr_moved && this_cpu != smp_processor_id())
2585 resched_cpu(this_cpu);
2587 /* All tasks on this runqueue were pinned by CPU affinity */
2588 if (unlikely(all_pinned)) {
2589 cpu_clear(cpu_of(busiest), cpus);
2590 if (!cpus_empty(cpus))
2597 schedstat_inc(sd, lb_failed[idle]);
2598 sd->nr_balance_failed++;
2600 if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
2602 spin_lock_irqsave(&busiest->lock, flags);
2604 /* don't kick the migration_thread, if the curr
2605 * task on busiest cpu can't be moved to this_cpu
2607 if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) {
2608 spin_unlock_irqrestore(&busiest->lock, flags);
2610 goto out_one_pinned;
2613 if (!busiest->active_balance) {
2614 busiest->active_balance = 1;
2615 busiest->push_cpu = this_cpu;
2618 spin_unlock_irqrestore(&busiest->lock, flags);
2620 wake_up_process(busiest->migration_thread);
2623 * We've kicked active balancing, reset the failure
2626 sd->nr_balance_failed = sd->cache_nice_tries+1;
2629 sd->nr_balance_failed = 0;
2631 if (likely(!active_balance)) {
2632 /* We were unbalanced, so reset the balancing interval */
2633 sd->balance_interval = sd->min_interval;
2636 * If we've begun active balancing, start to back off. This
2637 * case may not be covered by the all_pinned logic if there
2638 * is only 1 task on the busy runqueue (because we don't call
2641 if (sd->balance_interval < sd->max_interval)
2642 sd->balance_interval *= 2;
2645 if (!nr_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2646 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2651 schedstat_inc(sd, lb_balanced[idle]);
2653 sd->nr_balance_failed = 0;
2656 /* tune up the balancing interval */
2657 if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
2658 (sd->balance_interval < sd->max_interval))
2659 sd->balance_interval *= 2;
2661 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2662 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2668 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2669 * tasks if there is an imbalance.
2671 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
2672 * this_rq is locked.
2675 load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
2677 struct sched_group *group;
2678 struct rq *busiest = NULL;
2679 unsigned long imbalance;
2682 cpumask_t cpus = CPU_MASK_ALL;
2685 * When power savings policy is enabled for the parent domain, idle
2686 * sibling can pick up load irrespective of busy siblings. In this case,
2687 * let the state of idle sibling percolate up as IDLE, instead of
2688 * portraying it as CPU_NOT_IDLE.
2690 if (sd->flags & SD_SHARE_CPUPOWER &&
2691 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2694 schedstat_inc(sd, lb_cnt[CPU_NEWLY_IDLE]);
2696 group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE,
2697 &sd_idle, &cpus, NULL);
2699 schedstat_inc(sd, lb_nobusyg[CPU_NEWLY_IDLE]);
2703 busiest = find_busiest_queue(group, CPU_NEWLY_IDLE, imbalance,
2706 schedstat_inc(sd, lb_nobusyq[CPU_NEWLY_IDLE]);
2710 BUG_ON(busiest == this_rq);
2712 schedstat_add(sd, lb_imbalance[CPU_NEWLY_IDLE], imbalance);
2715 if (busiest->nr_running > 1) {
2716 /* Attempt to move tasks */
2717 double_lock_balance(this_rq, busiest);
2718 nr_moved = move_tasks(this_rq, this_cpu, busiest,
2719 minus_1_or_zero(busiest->nr_running),
2720 imbalance, sd, CPU_NEWLY_IDLE, NULL);
2721 spin_unlock(&busiest->lock);
2724 cpu_clear(cpu_of(busiest), cpus);
2725 if (!cpus_empty(cpus))
2731 schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
2732 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2733 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2736 sd->nr_balance_failed = 0;
2741 schedstat_inc(sd, lb_balanced[CPU_NEWLY_IDLE]);
2742 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2743 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2745 sd->nr_balance_failed = 0;
2751 * idle_balance is called by schedule() if this_cpu is about to become
2752 * idle. Attempts to pull tasks from other CPUs.
2754 static void idle_balance(int this_cpu, struct rq *this_rq)
2756 struct sched_domain *sd;
2757 int pulled_task = -1;
2758 unsigned long next_balance = jiffies + HZ;
2760 for_each_domain(this_cpu, sd) {
2761 unsigned long interval;
2763 if (!(sd->flags & SD_LOAD_BALANCE))
2766 if (sd->flags & SD_BALANCE_NEWIDLE)
2767 /* If we've pulled tasks over stop searching: */
2768 pulled_task = load_balance_newidle(this_cpu,
2771 interval = msecs_to_jiffies(sd->balance_interval);
2772 if (time_after(next_balance, sd->last_balance + interval))
2773 next_balance = sd->last_balance + interval;
2777 if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
2779 * We are going idle. next_balance may be set based on
2780 * a busy processor. So reset next_balance.
2782 this_rq->next_balance = next_balance;
2787 * active_load_balance is run by migration threads. It pushes running tasks
2788 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2789 * running on each physical CPU where possible, and avoids physical /
2790 * logical imbalances.
2792 * Called with busiest_rq locked.
2794 static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
2796 int target_cpu = busiest_rq->push_cpu;
2797 struct sched_domain *sd;
2798 struct rq *target_rq;
2800 /* Is there any task to move? */
2801 if (busiest_rq->nr_running <= 1)
2804 target_rq = cpu_rq(target_cpu);
2807 * This condition is "impossible", if it occurs
2808 * we need to fix it. Originally reported by
2809 * Bjorn Helgaas on a 128-cpu setup.
2811 BUG_ON(busiest_rq == target_rq);
2813 /* move a task from busiest_rq to target_rq */
2814 double_lock_balance(busiest_rq, target_rq);
2816 /* Search for an sd spanning us and the target CPU. */
2817 for_each_domain(target_cpu, sd) {
2818 if ((sd->flags & SD_LOAD_BALANCE) &&
2819 cpu_isset(busiest_cpu, sd->span))
2824 schedstat_inc(sd, alb_cnt);
2826 if (move_tasks(target_rq, target_cpu, busiest_rq, 1,
2827 RTPRIO_TO_LOAD_WEIGHT(100), sd, CPU_IDLE,
2829 schedstat_inc(sd, alb_pushed);
2831 schedstat_inc(sd, alb_failed);
2833 spin_unlock(&target_rq->lock);
2838 atomic_t load_balancer;
2840 } nohz ____cacheline_aligned = {
2841 .load_balancer = ATOMIC_INIT(-1),
2842 .cpu_mask = CPU_MASK_NONE,
2846 * This routine will try to nominate the ilb (idle load balancing)
2847 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
2848 * load balancing on behalf of all those cpus. If all the cpus in the system
2849 * go into this tickless mode, then there will be no ilb owner (as there is
2850 * no need for one) and all the cpus will sleep till the next wakeup event
2853 * For the ilb owner, tick is not stopped. And this tick will be used
2854 * for idle load balancing. ilb owner will still be part of
2857 * While stopping the tick, this cpu will become the ilb owner if there
2858 * is no other owner. And will be the owner till that cpu becomes busy
2859 * or if all cpus in the system stop their ticks at which point
2860 * there is no need for ilb owner.
2862 * When the ilb owner becomes busy, it nominates another owner, during the
2863 * next busy scheduler_tick()
2865 int select_nohz_load_balancer(int stop_tick)
2867 int cpu = smp_processor_id();
2870 cpu_set(cpu, nohz.cpu_mask);
2871 cpu_rq(cpu)->in_nohz_recently = 1;
2874 * If we are going offline and still the leader, give up!
2876 if (cpu_is_offline(cpu) &&
2877 atomic_read(&nohz.load_balancer) == cpu) {
2878 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
2883 /* time for ilb owner also to sleep */
2884 if (cpus_weight(nohz.cpu_mask) == num_online_cpus()) {
2885 if (atomic_read(&nohz.load_balancer) == cpu)
2886 atomic_set(&nohz.load_balancer, -1);
2890 if (atomic_read(&nohz.load_balancer) == -1) {
2891 /* make me the ilb owner */
2892 if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
2894 } else if (atomic_read(&nohz.load_balancer) == cpu)
2897 if (!cpu_isset(cpu, nohz.cpu_mask))
2900 cpu_clear(cpu, nohz.cpu_mask);
2902 if (atomic_read(&nohz.load_balancer) == cpu)
2903 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
2910 static DEFINE_SPINLOCK(balancing);
2913 * It checks each scheduling domain to see if it is due to be balanced,
2914 * and initiates a balancing operation if so.
2916 * Balancing parameters are set up in arch_init_sched_domains.
2918 static inline void rebalance_domains(int cpu, enum cpu_idle_type idle)
2921 struct rq *rq = cpu_rq(cpu);
2922 unsigned long interval;
2923 struct sched_domain *sd;
2924 /* Earliest time when we have to do rebalance again */
2925 unsigned long next_balance = jiffies + 60*HZ;
2927 for_each_domain(cpu, sd) {
2928 if (!(sd->flags & SD_LOAD_BALANCE))
2931 interval = sd->balance_interval;
2932 if (idle != CPU_IDLE)
2933 interval *= sd->busy_factor;
2935 /* scale ms to jiffies */
2936 interval = msecs_to_jiffies(interval);
2937 if (unlikely(!interval))
2939 if (interval > HZ*NR_CPUS/10)
2940 interval = HZ*NR_CPUS/10;
2943 if (sd->flags & SD_SERIALIZE) {
2944 if (!spin_trylock(&balancing))
2948 if (time_after_eq(jiffies, sd->last_balance + interval)) {
2949 if (load_balance(cpu, rq, sd, idle, &balance)) {
2951 * We've pulled tasks over so either we're no
2952 * longer idle, or one of our SMT siblings is
2955 idle = CPU_NOT_IDLE;
2957 sd->last_balance = jiffies;
2959 if (sd->flags & SD_SERIALIZE)
2960 spin_unlock(&balancing);
2962 if (time_after(next_balance, sd->last_balance + interval))
2963 next_balance = sd->last_balance + interval;
2966 * Stop the load balance at this level. There is another
2967 * CPU in our sched group which is doing load balancing more
2973 rq->next_balance = next_balance;
2977 * run_rebalance_domains is triggered when needed from the scheduler tick.
2978 * In CONFIG_NO_HZ case, the idle load balance owner will do the
2979 * rebalancing for all the cpus for whom scheduler ticks are stopped.
2981 static void run_rebalance_domains(struct softirq_action *h)
2983 int this_cpu = smp_processor_id();
2984 struct rq *this_rq = cpu_rq(this_cpu);
2985 enum cpu_idle_type idle = this_rq->idle_at_tick ?
2986 CPU_IDLE : CPU_NOT_IDLE;
2988 rebalance_domains(this_cpu, idle);
2992 * If this cpu is the owner for idle load balancing, then do the
2993 * balancing on behalf of the other idle cpus whose ticks are
2996 if (this_rq->idle_at_tick &&
2997 atomic_read(&nohz.load_balancer) == this_cpu) {
2998 cpumask_t cpus = nohz.cpu_mask;
3002 cpu_clear(this_cpu, cpus);
3003 for_each_cpu_mask(balance_cpu, cpus) {
3005 * If this cpu gets work to do, stop the load balancing
3006 * work being done for other cpus. Next load
3007 * balancing owner will pick it up.
3012 rebalance_domains(balance_cpu, SCHED_IDLE);
3014 rq = cpu_rq(balance_cpu);
3015 if (time_after(this_rq->next_balance, rq->next_balance))
3016 this_rq->next_balance = rq->next_balance;
3023 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3025 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3026 * idle load balancing owner or decide to stop the periodic load balancing,
3027 * if the whole system is idle.
3029 static inline void trigger_load_balance(struct rq *rq, int cpu)
3033 * If we were in the nohz mode recently and busy at the current
3034 * scheduler tick, then check if we need to nominate new idle
3037 if (rq->in_nohz_recently && !rq->idle_at_tick) {
3038 rq->in_nohz_recently = 0;
3040 if (atomic_read(&nohz.load_balancer) == cpu) {
3041 cpu_clear(cpu, nohz.cpu_mask);
3042 atomic_set(&nohz.load_balancer, -1);
3045 if (atomic_read(&nohz.load_balancer) == -1) {
3047 * simple selection for now: Nominate the
3048 * first cpu in the nohz list to be the next
3051 * TBD: Traverse the sched domains and nominate
3052 * the nearest cpu in the nohz.cpu_mask.
3054 int ilb = first_cpu(nohz.cpu_mask);
3062 * If this cpu is idle and doing idle load balancing for all the
3063 * cpus with ticks stopped, is it time for that to stop?
3065 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
3066 cpus_weight(nohz.cpu_mask) == num_online_cpus()) {
3072 * If this cpu is idle and the idle load balancing is done by
3073 * someone else, then no need raise the SCHED_SOFTIRQ
3075 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
3076 cpu_isset(cpu, nohz.cpu_mask))
3079 if (time_after_eq(jiffies, rq->next_balance))
3080 raise_softirq(SCHED_SOFTIRQ);
3083 #else /* CONFIG_SMP */
3086 * on UP we do not need to balance between CPUs:
3088 static inline void idle_balance(int cpu, struct rq *rq)
3092 /* Avoid "used but not defined" warning on UP */
3093 static int balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
3094 unsigned long max_nr_move, unsigned long max_load_move,
3095 struct sched_domain *sd, enum cpu_idle_type idle,
3096 int *all_pinned, unsigned long *load_moved,
3097 int this_best_prio, int best_prio, int best_prio_seen,
3098 struct rq_iterator *iterator)
3107 DEFINE_PER_CPU(struct kernel_stat, kstat);
3109 EXPORT_PER_CPU_SYMBOL(kstat);
3112 * Return p->sum_exec_runtime plus any more ns on the sched_clock
3113 * that have not yet been banked in case the task is currently running.
3115 unsigned long long task_sched_runtime(struct task_struct *p)
3117 unsigned long flags;
3121 rq = task_rq_lock(p, &flags);
3122 ns = p->se.sum_exec_runtime;
3123 if (rq->curr == p) {
3124 delta_exec = rq_clock(rq) - p->se.exec_start;
3125 if ((s64)delta_exec > 0)
3128 task_rq_unlock(rq, &flags);
3134 * Account user cpu time to a process.
3135 * @p: the process that the cpu time gets accounted to
3136 * @hardirq_offset: the offset to subtract from hardirq_count()
3137 * @cputime: the cpu time spent in user space since the last update
3139 void account_user_time(struct task_struct *p, cputime_t cputime)
3141 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3144 p->utime = cputime_add(p->utime, cputime);
3146 /* Add user time to cpustat. */
3147 tmp = cputime_to_cputime64(cputime);
3148 if (TASK_NICE(p) > 0)
3149 cpustat->nice = cputime64_add(cpustat->nice, tmp);
3151 cpustat->user = cputime64_add(cpustat->user, tmp);
3155 * Account system cpu time to a process.
3156 * @p: the process that the cpu time gets accounted to
3157 * @hardirq_offset: the offset to subtract from hardirq_count()
3158 * @cputime: the cpu time spent in kernel space since the last update
3160 void account_system_time(struct task_struct *p, int hardirq_offset,
3163 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3164 struct rq *rq = this_rq();
3167 p->stime = cputime_add(p->stime, cputime);
3169 /* Add system time to cpustat. */
3170 tmp = cputime_to_cputime64(cputime);
3171 if (hardirq_count() - hardirq_offset)
3172 cpustat->irq = cputime64_add(cpustat->irq, tmp);
3173 else if (softirq_count())
3174 cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
3175 else if (p != rq->idle)
3176 cpustat->system = cputime64_add(cpustat->system, tmp);
3177 else if (atomic_read(&rq->nr_iowait) > 0)
3178 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
3180 cpustat->idle = cputime64_add(cpustat->idle, tmp);
3181 /* Account for system time used */
3182 acct_update_integrals(p);
3186 * Account for involuntary wait time.
3187 * @p: the process from which the cpu time has been stolen
3188 * @steal: the cpu time spent in involuntary wait
3190 void account_steal_time(struct task_struct *p, cputime_t steal)
3192 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3193 cputime64_t tmp = cputime_to_cputime64(steal);
3194 struct rq *rq = this_rq();
3196 if (p == rq->idle) {
3197 p->stime = cputime_add(p->stime, steal);
3198 if (atomic_read(&rq->nr_iowait) > 0)
3199 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
3201 cpustat->idle = cputime64_add(cpustat->idle, tmp);
3203 cpustat->steal = cputime64_add(cpustat->steal, tmp);
3207 * This function gets called by the timer code, with HZ frequency.
3208 * We call it with interrupts disabled.
3210 * It also gets called by the fork code, when changing the parent's
3213 void scheduler_tick(void)
3215 int cpu = smp_processor_id();
3216 struct rq *rq = cpu_rq(cpu);
3217 struct task_struct *curr = rq->curr;
3219 spin_lock(&rq->lock);
3220 if (curr != rq->idle) /* FIXME: needed? */
3221 curr->sched_class->task_tick(rq, curr);
3222 update_cpu_load(rq);
3223 spin_unlock(&rq->lock);
3226 rq->idle_at_tick = idle_cpu(cpu);
3227 trigger_load_balance(rq, cpu);
3231 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3233 void fastcall add_preempt_count(int val)
3238 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3240 preempt_count() += val;
3242 * Spinlock count overflowing soon?
3244 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
3247 EXPORT_SYMBOL(add_preempt_count);
3249 void fastcall sub_preempt_count(int val)
3254 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3257 * Is the spinlock portion underflowing?
3259 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3260 !(preempt_count() & PREEMPT_MASK)))
3263 preempt_count() -= val;
3265 EXPORT_SYMBOL(sub_preempt_count);
3270 * Print scheduling while atomic bug:
3272 static noinline void __schedule_bug(struct task_struct *prev)
3274 printk(KERN_ERR "BUG: scheduling while atomic: %s/0x%08x/%d\n",
3275 prev->comm, preempt_count(), prev->pid);
3276 debug_show_held_locks(prev);
3277 if (irqs_disabled())
3278 print_irqtrace_events(prev);
3283 * Various schedule()-time debugging checks and statistics:
3285 static inline void schedule_debug(struct task_struct *prev)
3288 * Test if we are atomic. Since do_exit() needs to call into
3289 * schedule() atomically, we ignore that path for now.
3290 * Otherwise, whine if we are scheduling when we should not be.
3292 if (unlikely(in_atomic_preempt_off()) && unlikely(!prev->exit_state))
3293 __schedule_bug(prev);
3295 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3297 schedstat_inc(this_rq(), sched_cnt);
3301 * Pick up the highest-prio task:
3303 static inline struct task_struct *
3304 pick_next_task(struct rq *rq, struct task_struct *prev, u64 now)
3306 struct sched_class *class;
3307 struct task_struct *p;
3310 * Optimization: we know that if all tasks are in
3311 * the fair class we can call that function directly:
3313 if (likely(rq->nr_running == rq->cfs.nr_running)) {
3314 p = fair_sched_class.pick_next_task(rq, now);
3319 class = sched_class_highest;
3321 p = class->pick_next_task(rq, now);
3325 * Will never be NULL as the idle class always
3326 * returns a non-NULL p:
3328 class = class->next;
3333 * schedule() is the main scheduler function.
3335 asmlinkage void __sched schedule(void)
3337 struct task_struct *prev, *next;
3345 cpu = smp_processor_id();
3349 switch_count = &prev->nivcsw;
3351 release_kernel_lock(prev);
3352 need_resched_nonpreemptible:
3354 schedule_debug(prev);
3356 spin_lock_irq(&rq->lock);
3357 clear_tsk_need_resched(prev);
3359 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
3360 if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
3361 unlikely(signal_pending(prev)))) {
3362 prev->state = TASK_RUNNING;
3364 deactivate_task(rq, prev, 1);
3366 switch_count = &prev->nvcsw;
3369 if (unlikely(!rq->nr_running))
3370 idle_balance(cpu, rq);
3372 now = __rq_clock(rq);
3373 prev->sched_class->put_prev_task(rq, prev, now);
3374 next = pick_next_task(rq, prev, now);
3376 sched_info_switch(prev, next);
3378 if (likely(prev != next)) {
3383 context_switch(rq, prev, next); /* unlocks the rq */
3385 spin_unlock_irq(&rq->lock);
3387 if (unlikely(reacquire_kernel_lock(current) < 0)) {
3388 cpu = smp_processor_id();
3390 goto need_resched_nonpreemptible;
3392 preempt_enable_no_resched();
3393 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3396 EXPORT_SYMBOL(schedule);
3398 #ifdef CONFIG_PREEMPT
3400 * this is the entry point to schedule() from in-kernel preemption
3401 * off of preempt_enable. Kernel preemptions off return from interrupt
3402 * occur there and call schedule directly.
3404 asmlinkage void __sched preempt_schedule(void)
3406 struct thread_info *ti = current_thread_info();
3407 #ifdef CONFIG_PREEMPT_BKL
3408 struct task_struct *task = current;
3409 int saved_lock_depth;
3412 * If there is a non-zero preempt_count or interrupts are disabled,
3413 * we do not want to preempt the current task. Just return..
3415 if (likely(ti->preempt_count || irqs_disabled()))
3419 add_preempt_count(PREEMPT_ACTIVE);
3421 * We keep the big kernel semaphore locked, but we
3422 * clear ->lock_depth so that schedule() doesnt
3423 * auto-release the semaphore:
3425 #ifdef CONFIG_PREEMPT_BKL
3426 saved_lock_depth = task->lock_depth;
3427 task->lock_depth = -1;
3430 #ifdef CONFIG_PREEMPT_BKL
3431 task->lock_depth = saved_lock_depth;
3433 sub_preempt_count(PREEMPT_ACTIVE);
3435 /* we could miss a preemption opportunity between schedule and now */
3437 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3440 EXPORT_SYMBOL(preempt_schedule);
3443 * this is the entry point to schedule() from kernel preemption
3444 * off of irq context.
3445 * Note, that this is called and return with irqs disabled. This will
3446 * protect us against recursive calling from irq.
3448 asmlinkage void __sched preempt_schedule_irq(void)
3450 struct thread_info *ti = current_thread_info();
3451 #ifdef CONFIG_PREEMPT_BKL
3452 struct task_struct *task = current;
3453 int saved_lock_depth;
3455 /* Catch callers which need to be fixed */
3456 BUG_ON(ti->preempt_count || !irqs_disabled());
3459 add_preempt_count(PREEMPT_ACTIVE);
3461 * We keep the big kernel semaphore locked, but we
3462 * clear ->lock_depth so that schedule() doesnt
3463 * auto-release the semaphore:
3465 #ifdef CONFIG_PREEMPT_BKL
3466 saved_lock_depth = task->lock_depth;
3467 task->lock_depth = -1;
3471 local_irq_disable();
3472 #ifdef CONFIG_PREEMPT_BKL
3473 task->lock_depth = saved_lock_depth;
3475 sub_preempt_count(PREEMPT_ACTIVE);
3477 /* we could miss a preemption opportunity between schedule and now */
3479 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3483 #endif /* CONFIG_PREEMPT */
3485 int default_wake_function(wait_queue_t *curr, unsigned mode, int sync,
3488 return try_to_wake_up(curr->private, mode, sync);
3490 EXPORT_SYMBOL(default_wake_function);
3493 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3494 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3495 * number) then we wake all the non-exclusive tasks and one exclusive task.
3497 * There are circumstances in which we can try to wake a task which has already
3498 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3499 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3501 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
3502 int nr_exclusive, int sync, void *key)
3504 struct list_head *tmp, *next;
3506 list_for_each_safe(tmp, next, &q->task_list) {
3507 wait_queue_t *curr = list_entry(tmp, wait_queue_t, task_list);
3508 unsigned flags = curr->flags;
3510 if (curr->func(curr, mode, sync, key) &&
3511 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
3517 * __wake_up - wake up threads blocked on a waitqueue.
3519 * @mode: which threads
3520 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3521 * @key: is directly passed to the wakeup function
3523 void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
3524 int nr_exclusive, void *key)
3526 unsigned long flags;
3528 spin_lock_irqsave(&q->lock, flags);
3529 __wake_up_common(q, mode, nr_exclusive, 0, key);
3530 spin_unlock_irqrestore(&q->lock, flags);
3532 EXPORT_SYMBOL(__wake_up);
3535 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3537 void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
3539 __wake_up_common(q, mode, 1, 0, NULL);
3543 * __wake_up_sync - wake up threads blocked on a waitqueue.
3545 * @mode: which threads
3546 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3548 * The sync wakeup differs that the waker knows that it will schedule
3549 * away soon, so while the target thread will be woken up, it will not
3550 * be migrated to another CPU - ie. the two threads are 'synchronized'
3551 * with each other. This can prevent needless bouncing between CPUs.
3553 * On UP it can prevent extra preemption.
3556 __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
3558 unsigned long flags;
3564 if (unlikely(!nr_exclusive))
3567 spin_lock_irqsave(&q->lock, flags);
3568 __wake_up_common(q, mode, nr_exclusive, sync, NULL);
3569 spin_unlock_irqrestore(&q->lock, flags);
3571 EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
3573 void fastcall complete(struct completion *x)
3575 unsigned long flags;
3577 spin_lock_irqsave(&x->wait.lock, flags);
3579 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3581 spin_unlock_irqrestore(&x->wait.lock, flags);
3583 EXPORT_SYMBOL(complete);
3585 void fastcall complete_all(struct completion *x)
3587 unsigned long flags;
3589 spin_lock_irqsave(&x->wait.lock, flags);
3590 x->done += UINT_MAX/2;
3591 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3593 spin_unlock_irqrestore(&x->wait.lock, flags);
3595 EXPORT_SYMBOL(complete_all);
3597 void fastcall __sched wait_for_completion(struct completion *x)
3601 spin_lock_irq(&x->wait.lock);
3603 DECLARE_WAITQUEUE(wait, current);
3605 wait.flags |= WQ_FLAG_EXCLUSIVE;
3606 __add_wait_queue_tail(&x->wait, &wait);
3608 __set_current_state(TASK_UNINTERRUPTIBLE);
3609 spin_unlock_irq(&x->wait.lock);
3611 spin_lock_irq(&x->wait.lock);
3613 __remove_wait_queue(&x->wait, &wait);
3616 spin_unlock_irq(&x->wait.lock);
3618 EXPORT_SYMBOL(wait_for_completion);
3620 unsigned long fastcall __sched
3621 wait_for_completion_timeout(struct completion *x, unsigned long timeout)
3625 spin_lock_irq(&x->wait.lock);
3627 DECLARE_WAITQUEUE(wait, current);
3629 wait.flags |= WQ_FLAG_EXCLUSIVE;
3630 __add_wait_queue_tail(&x->wait, &wait);
3632 __set_current_state(TASK_UNINTERRUPTIBLE);
3633 spin_unlock_irq(&x->wait.lock);
3634 timeout = schedule_timeout(timeout);
3635 spin_lock_irq(&x->wait.lock);
3637 __remove_wait_queue(&x->wait, &wait);
3641 __remove_wait_queue(&x->wait, &wait);
3645 spin_unlock_irq(&x->wait.lock);
3648 EXPORT_SYMBOL(wait_for_completion_timeout);
3650 int fastcall __sched wait_for_completion_interruptible(struct completion *x)
3656 spin_lock_irq(&x->wait.lock);
3658 DECLARE_WAITQUEUE(wait, current);
3660 wait.flags |= WQ_FLAG_EXCLUSIVE;
3661 __add_wait_queue_tail(&x->wait, &wait);
3663 if (signal_pending(current)) {
3665 __remove_wait_queue(&x->wait, &wait);
3668 __set_current_state(TASK_INTERRUPTIBLE);
3669 spin_unlock_irq(&x->wait.lock);
3671 spin_lock_irq(&x->wait.lock);
3673 __remove_wait_queue(&x->wait, &wait);
3677 spin_unlock_irq(&x->wait.lock);
3681 EXPORT_SYMBOL(wait_for_completion_interruptible);
3683 unsigned long fastcall __sched
3684 wait_for_completion_interruptible_timeout(struct completion *x,
3685 unsigned long timeout)
3689 spin_lock_irq(&x->wait.lock);
3691 DECLARE_WAITQUEUE(wait, current);
3693 wait.flags |= WQ_FLAG_EXCLUSIVE;
3694 __add_wait_queue_tail(&x->wait, &wait);
3696 if (signal_pending(current)) {
3697 timeout = -ERESTARTSYS;
3698 __remove_wait_queue(&x->wait, &wait);
3701 __set_current_state(TASK_INTERRUPTIBLE);
3702 spin_unlock_irq(&x->wait.lock);
3703 timeout = schedule_timeout(timeout);
3704 spin_lock_irq(&x->wait.lock);
3706 __remove_wait_queue(&x->wait, &wait);
3710 __remove_wait_queue(&x->wait, &wait);
3714 spin_unlock_irq(&x->wait.lock);
3717 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
3720 sleep_on_head(wait_queue_head_t *q, wait_queue_t *wait, unsigned long *flags)
3722 spin_lock_irqsave(&q->lock, *flags);
3723 __add_wait_queue(q, wait);
3724 spin_unlock(&q->lock);
3728 sleep_on_tail(wait_queue_head_t *q, wait_queue_t *wait, unsigned long *flags)
3730 spin_lock_irq(&q->lock);
3731 __remove_wait_queue(q, wait);
3732 spin_unlock_irqrestore(&q->lock, *flags);
3735 void __sched interruptible_sleep_on(wait_queue_head_t *q)
3737 unsigned long flags;
3740 init_waitqueue_entry(&wait, current);
3742 current->state = TASK_INTERRUPTIBLE;
3744 sleep_on_head(q, &wait, &flags);
3746 sleep_on_tail(q, &wait, &flags);
3748 EXPORT_SYMBOL(interruptible_sleep_on);
3751 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
3753 unsigned long flags;
3756 init_waitqueue_entry(&wait, current);
3758 current->state = TASK_INTERRUPTIBLE;
3760 sleep_on_head(q, &wait, &flags);
3761 timeout = schedule_timeout(timeout);
3762 sleep_on_tail(q, &wait, &flags);
3766 EXPORT_SYMBOL(interruptible_sleep_on_timeout);
3768 void __sched sleep_on(wait_queue_head_t *q)
3770 unsigned long flags;
3773 init_waitqueue_entry(&wait, current);
3775 current->state = TASK_UNINTERRUPTIBLE;
3777 sleep_on_head(q, &wait, &flags);
3779 sleep_on_tail(q, &wait, &flags);
3781 EXPORT_SYMBOL(sleep_on);
3783 long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
3785 unsigned long flags;
3788 init_waitqueue_entry(&wait, current);
3790 current->state = TASK_UNINTERRUPTIBLE;
3792 sleep_on_head(q, &wait, &flags);
3793 timeout = schedule_timeout(timeout);
3794 sleep_on_tail(q, &wait, &flags);
3798 EXPORT_SYMBOL(sleep_on_timeout);
3800 #ifdef CONFIG_RT_MUTEXES
3803 * rt_mutex_setprio - set the current priority of a task
3805 * @prio: prio value (kernel-internal form)
3807 * This function changes the 'effective' priority of a task. It does
3808 * not touch ->normal_prio like __setscheduler().
3810 * Used by the rt_mutex code to implement priority inheritance logic.
3812 void rt_mutex_setprio(struct task_struct *p, int prio)
3814 unsigned long flags;
3819 BUG_ON(prio < 0 || prio > MAX_PRIO);
3821 rq = task_rq_lock(p, &flags);
3825 on_rq = p->se.on_rq;
3827 dequeue_task(rq, p, 0, now);
3830 p->sched_class = &rt_sched_class;
3832 p->sched_class = &fair_sched_class;
3837 enqueue_task(rq, p, 0, now);
3839 * Reschedule if we are currently running on this runqueue and
3840 * our priority decreased, or if we are not currently running on
3841 * this runqueue and our priority is higher than the current's
3843 if (task_running(rq, p)) {
3844 if (p->prio > oldprio)
3845 resched_task(rq->curr);
3847 check_preempt_curr(rq, p);
3850 task_rq_unlock(rq, &flags);
3855 void set_user_nice(struct task_struct *p, long nice)
3857 int old_prio, delta, on_rq;
3858 unsigned long flags;
3862 if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
3865 * We have to be careful, if called from sys_setpriority(),
3866 * the task might be in the middle of scheduling on another CPU.
3868 rq = task_rq_lock(p, &flags);
3871 * The RT priorities are set via sched_setscheduler(), but we still
3872 * allow the 'normal' nice value to be set - but as expected
3873 * it wont have any effect on scheduling until the task is
3874 * SCHED_FIFO/SCHED_RR:
3876 if (task_has_rt_policy(p)) {
3877 p->static_prio = NICE_TO_PRIO(nice);
3880 on_rq = p->se.on_rq;
3882 dequeue_task(rq, p, 0, now);
3883 dec_load(rq, p, now);
3886 p->static_prio = NICE_TO_PRIO(nice);
3889 p->prio = effective_prio(p);
3890 delta = p->prio - old_prio;
3893 enqueue_task(rq, p, 0, now);
3894 inc_load(rq, p, now);
3896 * If the task increased its priority or is running and
3897 * lowered its priority, then reschedule its CPU:
3899 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3900 resched_task(rq->curr);
3903 task_rq_unlock(rq, &flags);
3905 EXPORT_SYMBOL(set_user_nice);
3908 * can_nice - check if a task can reduce its nice value
3912 int can_nice(const struct task_struct *p, const int nice)
3914 /* convert nice value [19,-20] to rlimit style value [1,40] */
3915 int nice_rlim = 20 - nice;
3917 return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
3918 capable(CAP_SYS_NICE));
3921 #ifdef __ARCH_WANT_SYS_NICE
3924 * sys_nice - change the priority of the current process.
3925 * @increment: priority increment
3927 * sys_setpriority is a more generic, but much slower function that
3928 * does similar things.
3930 asmlinkage long sys_nice(int increment)
3935 * Setpriority might change our priority at the same moment.
3936 * We don't have to worry. Conceptually one call occurs first
3937 * and we have a single winner.
3939 if (increment < -40)
3944 nice = PRIO_TO_NICE(current->static_prio) + increment;
3950 if (increment < 0 && !can_nice(current, nice))
3953 retval = security_task_setnice(current, nice);
3957 set_user_nice(current, nice);
3964 * task_prio - return the priority value of a given task.
3965 * @p: the task in question.
3967 * This is the priority value as seen by users in /proc.
3968 * RT tasks are offset by -200. Normal tasks are centered
3969 * around 0, value goes from -16 to +15.
3971 int task_prio(const struct task_struct *p)
3973 return p->prio - MAX_RT_PRIO;
3977 * task_nice - return the nice value of a given task.
3978 * @p: the task in question.
3980 int task_nice(const struct task_struct *p)
3982 return TASK_NICE(p);
3984 EXPORT_SYMBOL_GPL(task_nice);
3987 * idle_cpu - is a given cpu idle currently?
3988 * @cpu: the processor in question.
3990 int idle_cpu(int cpu)
3992 return cpu_curr(cpu) == cpu_rq(cpu)->idle;
3996 * idle_task - return the idle task for a given cpu.
3997 * @cpu: the processor in question.
3999 struct task_struct *idle_task(int cpu)
4001 return cpu_rq(cpu)->idle;
4005 * find_process_by_pid - find a process with a matching PID value.
4006 * @pid: the pid in question.
4008 static inline struct task_struct *find_process_by_pid(pid_t pid)
4010 return pid ? find_task_by_pid(pid) : current;
4013 /* Actually do priority change: must hold rq lock. */
4015 __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
4017 BUG_ON(p->se.on_rq);
4020 switch (p->policy) {
4024 p->sched_class = &fair_sched_class;
4028 p->sched_class = &rt_sched_class;
4032 p->rt_priority = prio;
4033 p->normal_prio = normal_prio(p);
4034 /* we are holding p->pi_lock already */
4035 p->prio = rt_mutex_getprio(p);
4040 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4041 * @p: the task in question.
4042 * @policy: new policy.
4043 * @param: structure containing the new RT priority.
4045 * NOTE that the task may be already dead.
4047 int sched_setscheduler(struct task_struct *p, int policy,
4048 struct sched_param *param)
4050 int retval, oldprio, oldpolicy = -1, on_rq;
4051 unsigned long flags;
4054 /* may grab non-irq protected spin_locks */
4055 BUG_ON(in_interrupt());
4057 /* double check policy once rq lock held */
4059 policy = oldpolicy = p->policy;
4060 else if (policy != SCHED_FIFO && policy != SCHED_RR &&
4061 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
4062 policy != SCHED_IDLE)
4065 * Valid priorities for SCHED_FIFO and SCHED_RR are
4066 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4067 * SCHED_BATCH and SCHED_IDLE is 0.
4069 if (param->sched_priority < 0 ||
4070 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
4071 (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
4073 if (rt_policy(policy) != (param->sched_priority != 0))
4077 * Allow unprivileged RT tasks to decrease priority:
4079 if (!capable(CAP_SYS_NICE)) {
4080 if (rt_policy(policy)) {
4081 unsigned long rlim_rtprio;
4083 if (!lock_task_sighand(p, &flags))
4085 rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
4086 unlock_task_sighand(p, &flags);
4088 /* can't set/change the rt policy */
4089 if (policy != p->policy && !rlim_rtprio)
4092 /* can't increase priority */
4093 if (param->sched_priority > p->rt_priority &&
4094 param->sched_priority > rlim_rtprio)
4098 * Like positive nice levels, dont allow tasks to
4099 * move out of SCHED_IDLE either:
4101 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE)
4104 /* can't change other user's priorities */
4105 if ((current->euid != p->euid) &&
4106 (current->euid != p->uid))
4110 retval = security_task_setscheduler(p, policy, param);
4114 * make sure no PI-waiters arrive (or leave) while we are
4115 * changing the priority of the task:
4117 spin_lock_irqsave(&p->pi_lock, flags);
4119 * To be able to change p->policy safely, the apropriate
4120 * runqueue lock must be held.
4122 rq = __task_rq_lock(p);
4123 /* recheck policy now with rq lock held */
4124 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
4125 policy = oldpolicy = -1;
4126 __task_rq_unlock(rq);
4127 spin_unlock_irqrestore(&p->pi_lock, flags);
4130 on_rq = p->se.on_rq;
4132 deactivate_task(rq, p, 0);
4134 __setscheduler(rq, p, policy, param->sched_priority);
4136 activate_task(rq, p, 0);
4138 * Reschedule if we are currently running on this runqueue and
4139 * our priority decreased, or if we are not currently running on
4140 * this runqueue and our priority is higher than the current's
4142 if (task_running(rq, p)) {
4143 if (p->prio > oldprio)
4144 resched_task(rq->curr);
4146 check_preempt_curr(rq, p);
4149 __task_rq_unlock(rq);
4150 spin_unlock_irqrestore(&p->pi_lock, flags);
4152 rt_mutex_adjust_pi(p);
4156 EXPORT_SYMBOL_GPL(sched_setscheduler);
4159 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4161 struct sched_param lparam;
4162 struct task_struct *p;
4165 if (!param || pid < 0)
4167 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4172 p = find_process_by_pid(pid);
4174 retval = sched_setscheduler(p, policy, &lparam);
4181 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4182 * @pid: the pid in question.
4183 * @policy: new policy.
4184 * @param: structure containing the new RT priority.
4186 asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
4187 struct sched_param __user *param)
4189 /* negative values for policy are not valid */
4193 return do_sched_setscheduler(pid, policy, param);
4197 * sys_sched_setparam - set/change the RT priority of a thread
4198 * @pid: the pid in question.
4199 * @param: structure containing the new RT priority.
4201 asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
4203 return do_sched_setscheduler(pid, -1, param);
4207 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4208 * @pid: the pid in question.
4210 asmlinkage long sys_sched_getscheduler(pid_t pid)
4212 struct task_struct *p;
4213 int retval = -EINVAL;
4219 read_lock(&tasklist_lock);
4220 p = find_process_by_pid(pid);
4222 retval = security_task_getscheduler(p);
4226 read_unlock(&tasklist_lock);
4233 * sys_sched_getscheduler - get the RT priority of a thread
4234 * @pid: the pid in question.
4235 * @param: structure containing the RT priority.
4237 asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
4239 struct sched_param lp;
4240 struct task_struct *p;
4241 int retval = -EINVAL;
4243 if (!param || pid < 0)
4246 read_lock(&tasklist_lock);
4247 p = find_process_by_pid(pid);
4252 retval = security_task_getscheduler(p);
4256 lp.sched_priority = p->rt_priority;
4257 read_unlock(&tasklist_lock);
4260 * This one might sleep, we cannot do it with a spinlock held ...
4262 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4268 read_unlock(&tasklist_lock);
4272 long sched_setaffinity(pid_t pid, cpumask_t new_mask)
4274 cpumask_t cpus_allowed;
4275 struct task_struct *p;
4278 mutex_lock(&sched_hotcpu_mutex);
4279 read_lock(&tasklist_lock);
4281 p = find_process_by_pid(pid);
4283 read_unlock(&tasklist_lock);
4284 mutex_unlock(&sched_hotcpu_mutex);
4289 * It is not safe to call set_cpus_allowed with the
4290 * tasklist_lock held. We will bump the task_struct's
4291 * usage count and then drop tasklist_lock.
4294 read_unlock(&tasklist_lock);
4297 if ((current->euid != p->euid) && (current->euid != p->uid) &&
4298 !capable(CAP_SYS_NICE))
4301 retval = security_task_setscheduler(p, 0, NULL);
4305 cpus_allowed = cpuset_cpus_allowed(p);
4306 cpus_and(new_mask, new_mask, cpus_allowed);
4307 retval = set_cpus_allowed(p, new_mask);
4311 mutex_unlock(&sched_hotcpu_mutex);
4315 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4316 cpumask_t *new_mask)
4318 if (len < sizeof(cpumask_t)) {
4319 memset(new_mask, 0, sizeof(cpumask_t));
4320 } else if (len > sizeof(cpumask_t)) {
4321 len = sizeof(cpumask_t);
4323 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4327 * sys_sched_setaffinity - set the cpu affinity of a process
4328 * @pid: pid of the process
4329 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4330 * @user_mask_ptr: user-space pointer to the new cpu mask
4332 asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
4333 unsigned long __user *user_mask_ptr)
4338 retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
4342 return sched_setaffinity(pid, new_mask);
4346 * Represents all cpu's present in the system
4347 * In systems capable of hotplug, this map could dynamically grow
4348 * as new cpu's are detected in the system via any platform specific
4349 * method, such as ACPI for e.g.
4352 cpumask_t cpu_present_map __read_mostly;
4353 EXPORT_SYMBOL(cpu_present_map);
4356 cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
4357 EXPORT_SYMBOL(cpu_online_map);
4359 cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
4360 EXPORT_SYMBOL(cpu_possible_map);
4363 long sched_getaffinity(pid_t pid, cpumask_t *mask)
4365 struct task_struct *p;
4368 mutex_lock(&sched_hotcpu_mutex);
4369 read_lock(&tasklist_lock);
4372 p = find_process_by_pid(pid);
4376 retval = security_task_getscheduler(p);
4380 cpus_and(*mask, p->cpus_allowed, cpu_online_map);
4383 read_unlock(&tasklist_lock);
4384 mutex_unlock(&sched_hotcpu_mutex);
4392 * sys_sched_getaffinity - get the cpu affinity of a process
4393 * @pid: pid of the process
4394 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4395 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4397 asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
4398 unsigned long __user *user_mask_ptr)
4403 if (len < sizeof(cpumask_t))
4406 ret = sched_getaffinity(pid, &mask);
4410 if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
4413 return sizeof(cpumask_t);
4417 * sys_sched_yield - yield the current processor to other threads.
4419 * This function yields the current CPU to other tasks. If there are no
4420 * other threads running on this CPU then this function will return.
4422 asmlinkage long sys_sched_yield(void)
4424 struct rq *rq = this_rq_lock();
4426 schedstat_inc(rq, yld_cnt);
4427 if (unlikely(rq->nr_running == 1))
4428 schedstat_inc(rq, yld_act_empty);
4430 current->sched_class->yield_task(rq, current);
4433 * Since we are going to call schedule() anyway, there's
4434 * no need to preempt or enable interrupts:
4436 __release(rq->lock);
4437 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4438 _raw_spin_unlock(&rq->lock);
4439 preempt_enable_no_resched();
4446 static void __cond_resched(void)
4448 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4449 __might_sleep(__FILE__, __LINE__);
4452 * The BKS might be reacquired before we have dropped
4453 * PREEMPT_ACTIVE, which could trigger a second
4454 * cond_resched() call.
4457 add_preempt_count(PREEMPT_ACTIVE);
4459 sub_preempt_count(PREEMPT_ACTIVE);
4460 } while (need_resched());
4463 int __sched cond_resched(void)
4465 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&
4466 system_state == SYSTEM_RUNNING) {
4472 EXPORT_SYMBOL(cond_resched);
4475 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4476 * call schedule, and on return reacquire the lock.
4478 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4479 * operations here to prevent schedule() from being called twice (once via
4480 * spin_unlock(), once by hand).
4482 int cond_resched_lock(spinlock_t *lock)
4486 if (need_lockbreak(lock)) {
4492 if (need_resched() && system_state == SYSTEM_RUNNING) {
4493 spin_release(&lock->dep_map, 1, _THIS_IP_);
4494 _raw_spin_unlock(lock);
4495 preempt_enable_no_resched();
4502 EXPORT_SYMBOL(cond_resched_lock);
4504 int __sched cond_resched_softirq(void)
4506 BUG_ON(!in_softirq());
4508 if (need_resched() && system_state == SYSTEM_RUNNING) {
4516 EXPORT_SYMBOL(cond_resched_softirq);
4519 * yield - yield the current processor to other threads.
4521 * This is a shortcut for kernel-space yielding - it marks the
4522 * thread runnable and calls sys_sched_yield().
4524 void __sched yield(void)
4526 set_current_state(TASK_RUNNING);
4529 EXPORT_SYMBOL(yield);
4532 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4533 * that process accounting knows that this is a task in IO wait state.
4535 * But don't do that if it is a deliberate, throttling IO wait (this task
4536 * has set its backing_dev_info: the queue against which it should throttle)
4538 void __sched io_schedule(void)
4540 struct rq *rq = &__raw_get_cpu_var(runqueues);
4542 delayacct_blkio_start();
4543 atomic_inc(&rq->nr_iowait);
4545 atomic_dec(&rq->nr_iowait);
4546 delayacct_blkio_end();
4548 EXPORT_SYMBOL(io_schedule);
4550 long __sched io_schedule_timeout(long timeout)
4552 struct rq *rq = &__raw_get_cpu_var(runqueues);
4555 delayacct_blkio_start();
4556 atomic_inc(&rq->nr_iowait);
4557 ret = schedule_timeout(timeout);
4558 atomic_dec(&rq->nr_iowait);
4559 delayacct_blkio_end();
4564 * sys_sched_get_priority_max - return maximum RT priority.
4565 * @policy: scheduling class.
4567 * this syscall returns the maximum rt_priority that can be used
4568 * by a given scheduling class.
4570 asmlinkage long sys_sched_get_priority_max(int policy)
4577 ret = MAX_USER_RT_PRIO-1;
4589 * sys_sched_get_priority_min - return minimum RT priority.
4590 * @policy: scheduling class.
4592 * this syscall returns the minimum rt_priority that can be used
4593 * by a given scheduling class.
4595 asmlinkage long sys_sched_get_priority_min(int policy)
4613 * sys_sched_rr_get_interval - return the default timeslice of a process.
4614 * @pid: pid of the process.
4615 * @interval: userspace pointer to the timeslice value.
4617 * this syscall writes the default timeslice value of a given process
4618 * into the user-space timespec buffer. A value of '0' means infinity.
4621 long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
4623 struct task_struct *p;
4624 int retval = -EINVAL;
4631 read_lock(&tasklist_lock);
4632 p = find_process_by_pid(pid);
4636 retval = security_task_getscheduler(p);
4640 jiffies_to_timespec(p->policy == SCHED_FIFO ?
4641 0 : static_prio_timeslice(p->static_prio), &t);
4642 read_unlock(&tasklist_lock);
4643 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4647 read_unlock(&tasklist_lock);
4651 static const char stat_nam[] = "RSDTtZX";
4653 static void show_task(struct task_struct *p)
4655 unsigned long free = 0;
4658 state = p->state ? __ffs(p->state) + 1 : 0;
4659 printk("%-13.13s %c", p->comm,
4660 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4661 #if BITS_PER_LONG == 32
4662 if (state == TASK_RUNNING)
4663 printk(" running ");
4665 printk(" %08lx ", thread_saved_pc(p));
4667 if (state == TASK_RUNNING)
4668 printk(" running task ");
4670 printk(" %016lx ", thread_saved_pc(p));
4672 #ifdef CONFIG_DEBUG_STACK_USAGE
4674 unsigned long *n = end_of_stack(p);
4677 free = (unsigned long)n - (unsigned long)end_of_stack(p);
4680 printk("%5lu %5d %6d\n", free, p->pid, p->parent->pid);
4682 if (state != TASK_RUNNING)
4683 show_stack(p, NULL);
4686 void show_state_filter(unsigned long state_filter)
4688 struct task_struct *g, *p;
4690 #if BITS_PER_LONG == 32
4692 " task PC stack pid father\n");
4695 " task PC stack pid father\n");
4697 read_lock(&tasklist_lock);
4698 do_each_thread(g, p) {
4700 * reset the NMI-timeout, listing all files on a slow
4701 * console might take alot of time:
4703 touch_nmi_watchdog();
4704 if (!state_filter || (p->state & state_filter))
4706 } while_each_thread(g, p);
4708 touch_all_softlockup_watchdogs();
4710 #ifdef CONFIG_SCHED_DEBUG
4711 sysrq_sched_debug_show();
4713 read_unlock(&tasklist_lock);
4715 * Only show locks if all tasks are dumped:
4717 if (state_filter == -1)
4718 debug_show_all_locks();
4721 void __cpuinit init_idle_bootup_task(struct task_struct *idle)
4723 idle->sched_class = &idle_sched_class;
4727 * init_idle - set up an idle thread for a given CPU
4728 * @idle: task in question
4729 * @cpu: cpu the idle task belongs to
4731 * NOTE: this function does not set the idle thread's NEED_RESCHED
4732 * flag, to make booting more robust.
4734 void __cpuinit init_idle(struct task_struct *idle, int cpu)
4736 struct rq *rq = cpu_rq(cpu);
4737 unsigned long flags;
4740 idle->se.exec_start = sched_clock();
4742 idle->prio = idle->normal_prio = MAX_PRIO;
4743 idle->cpus_allowed = cpumask_of_cpu(cpu);
4744 __set_task_cpu(idle, cpu);
4746 spin_lock_irqsave(&rq->lock, flags);
4747 rq->curr = rq->idle = idle;
4748 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4751 spin_unlock_irqrestore(&rq->lock, flags);
4753 /* Set the preempt count _outside_ the spinlocks! */
4754 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4755 task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
4757 task_thread_info(idle)->preempt_count = 0;
4760 * The idle tasks have their own, simple scheduling class:
4762 idle->sched_class = &idle_sched_class;
4766 * In a system that switches off the HZ timer nohz_cpu_mask
4767 * indicates which cpus entered this state. This is used
4768 * in the rcu update to wait only for active cpus. For system
4769 * which do not switch off the HZ timer nohz_cpu_mask should
4770 * always be CPU_MASK_NONE.
4772 cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
4775 * Increase the granularity value when there are more CPUs,
4776 * because with more CPUs the 'effective latency' as visible
4777 * to users decreases. But the relationship is not linear,
4778 * so pick a second-best guess by going with the log2 of the
4781 * This idea comes from the SD scheduler of Con Kolivas:
4783 static inline void sched_init_granularity(void)
4785 unsigned int factor = 1 + ilog2(num_online_cpus());
4786 const unsigned long gran_limit = 100000000;
4788 sysctl_sched_granularity *= factor;
4789 if (sysctl_sched_granularity > gran_limit)
4790 sysctl_sched_granularity = gran_limit;
4792 sysctl_sched_runtime_limit = sysctl_sched_granularity * 4;
4793 sysctl_sched_wakeup_granularity = sysctl_sched_granularity / 2;
4798 * This is how migration works:
4800 * 1) we queue a struct migration_req structure in the source CPU's
4801 * runqueue and wake up that CPU's migration thread.
4802 * 2) we down() the locked semaphore => thread blocks.
4803 * 3) migration thread wakes up (implicitly it forces the migrated
4804 * thread off the CPU)
4805 * 4) it gets the migration request and checks whether the migrated
4806 * task is still in the wrong runqueue.
4807 * 5) if it's in the wrong runqueue then the migration thread removes
4808 * it and puts it into the right queue.
4809 * 6) migration thread up()s the semaphore.
4810 * 7) we wake up and the migration is done.
4814 * Change a given task's CPU affinity. Migrate the thread to a
4815 * proper CPU and schedule it away if the CPU it's executing on
4816 * is removed from the allowed bitmask.
4818 * NOTE: the caller must have a valid reference to the task, the
4819 * task must not exit() & deallocate itself prematurely. The
4820 * call is not atomic; no spinlocks may be held.
4822 int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
4824 struct migration_req req;
4825 unsigned long flags;
4829 rq = task_rq_lock(p, &flags);
4830 if (!cpus_intersects(new_mask, cpu_online_map)) {
4835 p->cpus_allowed = new_mask;
4836 /* Can the task run on the task's current CPU? If so, we're done */
4837 if (cpu_isset(task_cpu(p), new_mask))
4840 if (migrate_task(p, any_online_cpu(new_mask), &req)) {
4841 /* Need help from migration thread: drop lock and wait. */
4842 task_rq_unlock(rq, &flags);
4843 wake_up_process(rq->migration_thread);
4844 wait_for_completion(&req.done);
4845 tlb_migrate_finish(p->mm);
4849 task_rq_unlock(rq, &flags);
4853 EXPORT_SYMBOL_GPL(set_cpus_allowed);
4856 * Move (not current) task off this cpu, onto dest cpu. We're doing
4857 * this because either it can't run here any more (set_cpus_allowed()
4858 * away from this CPU, or CPU going down), or because we're
4859 * attempting to rebalance this task on exec (sched_exec).
4861 * So we race with normal scheduler movements, but that's OK, as long
4862 * as the task is no longer on this CPU.
4864 * Returns non-zero if task was successfully migrated.
4866 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4868 struct rq *rq_dest, *rq_src;
4871 if (unlikely(cpu_is_offline(dest_cpu)))
4874 rq_src = cpu_rq(src_cpu);
4875 rq_dest = cpu_rq(dest_cpu);
4877 double_rq_lock(rq_src, rq_dest);
4878 /* Already moved. */
4879 if (task_cpu(p) != src_cpu)
4881 /* Affinity changed (again). */
4882 if (!cpu_isset(dest_cpu, p->cpus_allowed))
4885 on_rq = p->se.on_rq;
4887 deactivate_task(rq_src, p, 0);
4888 set_task_cpu(p, dest_cpu);
4890 activate_task(rq_dest, p, 0);
4891 check_preempt_curr(rq_dest, p);
4895 double_rq_unlock(rq_src, rq_dest);
4900 * migration_thread - this is a highprio system thread that performs
4901 * thread migration by bumping thread off CPU then 'pushing' onto
4904 static int migration_thread(void *data)
4906 int cpu = (long)data;
4910 BUG_ON(rq->migration_thread != current);
4912 set_current_state(TASK_INTERRUPTIBLE);
4913 while (!kthread_should_stop()) {
4914 struct migration_req *req;
4915 struct list_head *head;
4917 spin_lock_irq(&rq->lock);
4919 if (cpu_is_offline(cpu)) {
4920 spin_unlock_irq(&rq->lock);
4924 if (rq->active_balance) {
4925 active_load_balance(rq, cpu);
4926 rq->active_balance = 0;
4929 head = &rq->migration_queue;
4931 if (list_empty(head)) {
4932 spin_unlock_irq(&rq->lock);
4934 set_current_state(TASK_INTERRUPTIBLE);
4937 req = list_entry(head->next, struct migration_req, list);
4938 list_del_init(head->next);
4940 spin_unlock(&rq->lock);
4941 __migrate_task(req->task, cpu, req->dest_cpu);
4944 complete(&req->done);
4946 __set_current_state(TASK_RUNNING);
4950 /* Wait for kthread_stop */
4951 set_current_state(TASK_INTERRUPTIBLE);
4952 while (!kthread_should_stop()) {
4954 set_current_state(TASK_INTERRUPTIBLE);
4956 __set_current_state(TASK_RUNNING);
4960 #ifdef CONFIG_HOTPLUG_CPU
4962 * Figure out where task on dead CPU should go, use force if neccessary.
4963 * NOTE: interrupts should be disabled by the caller
4965 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
4967 unsigned long flags;
4974 mask = node_to_cpumask(cpu_to_node(dead_cpu));
4975 cpus_and(mask, mask, p->cpus_allowed);
4976 dest_cpu = any_online_cpu(mask);
4978 /* On any allowed CPU? */
4979 if (dest_cpu == NR_CPUS)
4980 dest_cpu = any_online_cpu(p->cpus_allowed);
4982 /* No more Mr. Nice Guy. */
4983 if (dest_cpu == NR_CPUS) {
4984 rq = task_rq_lock(p, &flags);
4985 cpus_setall(p->cpus_allowed);
4986 dest_cpu = any_online_cpu(p->cpus_allowed);
4987 task_rq_unlock(rq, &flags);
4990 * Don't tell them about moving exiting tasks or
4991 * kernel threads (both mm NULL), since they never
4994 if (p->mm && printk_ratelimit())
4995 printk(KERN_INFO "process %d (%s) no "
4996 "longer affine to cpu%d\n",
4997 p->pid, p->comm, dead_cpu);
4999 if (!__migrate_task(p, dead_cpu, dest_cpu))
5004 * While a dead CPU has no uninterruptible tasks queued at this point,
5005 * it might still have a nonzero ->nr_uninterruptible counter, because
5006 * for performance reasons the counter is not stricly tracking tasks to
5007 * their home CPUs. So we just add the counter to another CPU's counter,
5008 * to keep the global sum constant after CPU-down:
5010 static void migrate_nr_uninterruptible(struct rq *rq_src)
5012 struct rq *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL));
5013 unsigned long flags;
5015 local_irq_save(flags);
5016 double_rq_lock(rq_src, rq_dest);
5017 rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
5018 rq_src->nr_uninterruptible = 0;
5019 double_rq_unlock(rq_src, rq_dest);
5020 local_irq_restore(flags);
5023 /* Run through task list and migrate tasks from the dead cpu. */
5024 static void migrate_live_tasks(int src_cpu)
5026 struct task_struct *p, *t;
5028 write_lock_irq(&tasklist_lock);
5030 do_each_thread(t, p) {
5034 if (task_cpu(p) == src_cpu)
5035 move_task_off_dead_cpu(src_cpu, p);
5036 } while_each_thread(t, p);
5038 write_unlock_irq(&tasklist_lock);
5042 * Schedules idle task to be the next runnable task on current CPU.
5043 * It does so by boosting its priority to highest possible and adding it to
5044 * the _front_ of the runqueue. Used by CPU offline code.
5046 void sched_idle_next(void)
5048 int this_cpu = smp_processor_id();
5049 struct rq *rq = cpu_rq(this_cpu);
5050 struct task_struct *p = rq->idle;
5051 unsigned long flags;
5053 /* cpu has to be offline */
5054 BUG_ON(cpu_online(this_cpu));
5057 * Strictly not necessary since rest of the CPUs are stopped by now
5058 * and interrupts disabled on the current cpu.
5060 spin_lock_irqsave(&rq->lock, flags);
5062 __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
5064 /* Add idle task to the _front_ of its priority queue: */
5065 activate_idle_task(p, rq);
5067 spin_unlock_irqrestore(&rq->lock, flags);
5071 * Ensures that the idle task is using init_mm right before its cpu goes
5074 void idle_task_exit(void)
5076 struct mm_struct *mm = current->active_mm;
5078 BUG_ON(cpu_online(smp_processor_id()));
5081 switch_mm(mm, &init_mm, current);
5085 /* called under rq->lock with disabled interrupts */
5086 static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
5088 struct rq *rq = cpu_rq(dead_cpu);
5090 /* Must be exiting, otherwise would be on tasklist. */
5091 BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD);
5093 /* Cannot have done final schedule yet: would have vanished. */
5094 BUG_ON(p->state == TASK_DEAD);
5099 * Drop lock around migration; if someone else moves it,
5100 * that's OK. No task can be added to this CPU, so iteration is
5102 * NOTE: interrupts should be left disabled --dev@
5104 spin_unlock(&rq->lock);
5105 move_task_off_dead_cpu(dead_cpu, p);
5106 spin_lock(&rq->lock);
5111 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5112 static void migrate_dead_tasks(unsigned int dead_cpu)
5114 struct rq *rq = cpu_rq(dead_cpu);
5115 struct task_struct *next;
5118 if (!rq->nr_running)
5120 next = pick_next_task(rq, rq->curr, rq_clock(rq));
5123 migrate_dead(dead_cpu, next);
5126 #endif /* CONFIG_HOTPLUG_CPU */
5129 * migration_call - callback that gets triggered when a CPU is added.
5130 * Here we can start up the necessary migration thread for the new CPU.
5132 static int __cpuinit
5133 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5135 struct task_struct *p;
5136 int cpu = (long)hcpu;
5137 unsigned long flags;
5141 case CPU_LOCK_ACQUIRE:
5142 mutex_lock(&sched_hotcpu_mutex);
5145 case CPU_UP_PREPARE:
5146 case CPU_UP_PREPARE_FROZEN:
5147 p = kthread_create(migration_thread, hcpu, "migration/%d", cpu);
5150 kthread_bind(p, cpu);
5151 /* Must be high prio: stop_machine expects to yield to it. */
5152 rq = task_rq_lock(p, &flags);
5153 __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1);
5154 task_rq_unlock(rq, &flags);
5155 cpu_rq(cpu)->migration_thread = p;
5159 case CPU_ONLINE_FROZEN:
5160 /* Strictly unneccessary, as first user will wake it. */
5161 wake_up_process(cpu_rq(cpu)->migration_thread);
5164 #ifdef CONFIG_HOTPLUG_CPU
5165 case CPU_UP_CANCELED:
5166 case CPU_UP_CANCELED_FROZEN:
5167 if (!cpu_rq(cpu)->migration_thread)
5169 /* Unbind it from offline cpu so it can run. Fall thru. */
5170 kthread_bind(cpu_rq(cpu)->migration_thread,
5171 any_online_cpu(cpu_online_map));
5172 kthread_stop(cpu_rq(cpu)->migration_thread);
5173 cpu_rq(cpu)->migration_thread = NULL;
5177 case CPU_DEAD_FROZEN:
5178 migrate_live_tasks(cpu);
5180 kthread_stop(rq->migration_thread);
5181 rq->migration_thread = NULL;
5182 /* Idle task back to normal (off runqueue, low prio) */
5183 rq = task_rq_lock(rq->idle, &flags);
5184 deactivate_task(rq, rq->idle, 0);
5185 rq->idle->static_prio = MAX_PRIO;
5186 __setscheduler(rq, rq->idle, SCHED_NORMAL, 0);
5187 rq->idle->sched_class = &idle_sched_class;
5188 migrate_dead_tasks(cpu);
5189 task_rq_unlock(rq, &flags);
5190 migrate_nr_uninterruptible(rq);
5191 BUG_ON(rq->nr_running != 0);
5193 /* No need to migrate the tasks: it was best-effort if
5194 * they didn't take sched_hotcpu_mutex. Just wake up
5195 * the requestors. */
5196 spin_lock_irq(&rq->lock);
5197 while (!list_empty(&rq->migration_queue)) {
5198 struct migration_req *req;
5200 req = list_entry(rq->migration_queue.next,
5201 struct migration_req, list);
5202 list_del_init(&req->list);
5203 complete(&req->done);
5205 spin_unlock_irq(&rq->lock);
5208 case CPU_LOCK_RELEASE:
5209 mutex_unlock(&sched_hotcpu_mutex);
5215 /* Register at highest priority so that task migration (migrate_all_tasks)
5216 * happens before everything else.
5218 static struct notifier_block __cpuinitdata migration_notifier = {
5219 .notifier_call = migration_call,
5223 int __init migration_init(void)
5225 void *cpu = (void *)(long)smp_processor_id();
5228 /* Start one for the boot CPU: */
5229 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5230 BUG_ON(err == NOTIFY_BAD);
5231 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5232 register_cpu_notifier(&migration_notifier);
5240 /* Number of possible processor ids */
5241 int nr_cpu_ids __read_mostly = NR_CPUS;
5242 EXPORT_SYMBOL(nr_cpu_ids);
5244 #undef SCHED_DOMAIN_DEBUG
5245 #ifdef SCHED_DOMAIN_DEBUG
5246 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5251 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5255 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5260 struct sched_group *group = sd->groups;
5261 cpumask_t groupmask;
5263 cpumask_scnprintf(str, NR_CPUS, sd->span);
5264 cpus_clear(groupmask);
5267 for (i = 0; i < level + 1; i++)
5269 printk("domain %d: ", level);
5271 if (!(sd->flags & SD_LOAD_BALANCE)) {
5272 printk("does not load-balance\n");
5274 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5279 printk("span %s\n", str);
5281 if (!cpu_isset(cpu, sd->span))
5282 printk(KERN_ERR "ERROR: domain->span does not contain "
5284 if (!cpu_isset(cpu, group->cpumask))
5285 printk(KERN_ERR "ERROR: domain->groups does not contain"
5289 for (i = 0; i < level + 2; i++)
5295 printk(KERN_ERR "ERROR: group is NULL\n");
5299 if (!group->__cpu_power) {
5301 printk(KERN_ERR "ERROR: domain->cpu_power not "
5305 if (!cpus_weight(group->cpumask)) {
5307 printk(KERN_ERR "ERROR: empty group\n");
5310 if (cpus_intersects(groupmask, group->cpumask)) {
5312 printk(KERN_ERR "ERROR: repeated CPUs\n");
5315 cpus_or(groupmask, groupmask, group->cpumask);
5317 cpumask_scnprintf(str, NR_CPUS, group->cpumask);
5320 group = group->next;
5321 } while (group != sd->groups);
5324 if (!cpus_equal(sd->span, groupmask))
5325 printk(KERN_ERR "ERROR: groups don't span "
5333 if (!cpus_subset(groupmask, sd->span))
5334 printk(KERN_ERR "ERROR: parent span is not a superset "
5335 "of domain->span\n");
5340 # define sched_domain_debug(sd, cpu) do { } while (0)
5343 static int sd_degenerate(struct sched_domain *sd)
5345 if (cpus_weight(sd->span) == 1)
5348 /* Following flags need at least 2 groups */
5349 if (sd->flags & (SD_LOAD_BALANCE |
5350 SD_BALANCE_NEWIDLE |
5354 SD_SHARE_PKG_RESOURCES)) {
5355 if (sd->groups != sd->groups->next)
5359 /* Following flags don't use groups */
5360 if (sd->flags & (SD_WAKE_IDLE |
5369 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5371 unsigned long cflags = sd->flags, pflags = parent->flags;
5373 if (sd_degenerate(parent))
5376 if (!cpus_equal(sd->span, parent->span))
5379 /* Does parent contain flags not in child? */
5380 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5381 if (cflags & SD_WAKE_AFFINE)
5382 pflags &= ~SD_WAKE_BALANCE;
5383 /* Flags needing groups don't count if only 1 group in parent */
5384 if (parent->groups == parent->groups->next) {
5385 pflags &= ~(SD_LOAD_BALANCE |
5386 SD_BALANCE_NEWIDLE |
5390 SD_SHARE_PKG_RESOURCES);
5392 if (~cflags & pflags)
5399 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5400 * hold the hotplug lock.
5402 static void cpu_attach_domain(struct sched_domain *sd, int cpu)
5404 struct rq *rq = cpu_rq(cpu);
5405 struct sched_domain *tmp;
5407 /* Remove the sched domains which do not contribute to scheduling. */
5408 for (tmp = sd; tmp; tmp = tmp->parent) {
5409 struct sched_domain *parent = tmp->parent;
5412 if (sd_parent_degenerate(tmp, parent)) {
5413 tmp->parent = parent->parent;
5415 parent->parent->child = tmp;
5419 if (sd && sd_degenerate(sd)) {
5425 sched_domain_debug(sd, cpu);
5427 rcu_assign_pointer(rq->sd, sd);
5430 /* cpus with isolated domains */
5431 static cpumask_t cpu_isolated_map = CPU_MASK_NONE;
5433 /* Setup the mask of cpus configured for isolated domains */
5434 static int __init isolated_cpu_setup(char *str)
5436 int ints[NR_CPUS], i;
5438 str = get_options(str, ARRAY_SIZE(ints), ints);
5439 cpus_clear(cpu_isolated_map);
5440 for (i = 1; i <= ints[0]; i++)
5441 if (ints[i] < NR_CPUS)
5442 cpu_set(ints[i], cpu_isolated_map);
5446 __setup ("isolcpus=", isolated_cpu_setup);
5449 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
5450 * to a function which identifies what group(along with sched group) a CPU
5451 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
5452 * (due to the fact that we keep track of groups covered with a cpumask_t).
5454 * init_sched_build_groups will build a circular linked list of the groups
5455 * covered by the given span, and will set each group's ->cpumask correctly,
5456 * and ->cpu_power to 0.
5459 init_sched_build_groups(cpumask_t span, const cpumask_t *cpu_map,
5460 int (*group_fn)(int cpu, const cpumask_t *cpu_map,
5461 struct sched_group **sg))
5463 struct sched_group *first = NULL, *last = NULL;
5464 cpumask_t covered = CPU_MASK_NONE;
5467 for_each_cpu_mask(i, span) {
5468 struct sched_group *sg;
5469 int group = group_fn(i, cpu_map, &sg);
5472 if (cpu_isset(i, covered))
5475 sg->cpumask = CPU_MASK_NONE;
5476 sg->__cpu_power = 0;
5478 for_each_cpu_mask(j, span) {
5479 if (group_fn(j, cpu_map, NULL) != group)
5482 cpu_set(j, covered);
5483 cpu_set(j, sg->cpumask);
5494 #define SD_NODES_PER_DOMAIN 16
5499 * find_next_best_node - find the next node to include in a sched_domain
5500 * @node: node whose sched_domain we're building
5501 * @used_nodes: nodes already in the sched_domain
5503 * Find the next node to include in a given scheduling domain. Simply
5504 * finds the closest node not already in the @used_nodes map.
5506 * Should use nodemask_t.
5508 static int find_next_best_node(int node, unsigned long *used_nodes)
5510 int i, n, val, min_val, best_node = 0;
5514 for (i = 0; i < MAX_NUMNODES; i++) {
5515 /* Start at @node */
5516 n = (node + i) % MAX_NUMNODES;
5518 if (!nr_cpus_node(n))
5521 /* Skip already used nodes */
5522 if (test_bit(n, used_nodes))
5525 /* Simple min distance search */
5526 val = node_distance(node, n);
5528 if (val < min_val) {
5534 set_bit(best_node, used_nodes);
5539 * sched_domain_node_span - get a cpumask for a node's sched_domain
5540 * @node: node whose cpumask we're constructing
5541 * @size: number of nodes to include in this span
5543 * Given a node, construct a good cpumask for its sched_domain to span. It
5544 * should be one that prevents unnecessary balancing, but also spreads tasks
5547 static cpumask_t sched_domain_node_span(int node)
5549 DECLARE_BITMAP(used_nodes, MAX_NUMNODES);
5550 cpumask_t span, nodemask;
5554 bitmap_zero(used_nodes, MAX_NUMNODES);
5556 nodemask = node_to_cpumask(node);
5557 cpus_or(span, span, nodemask);
5558 set_bit(node, used_nodes);
5560 for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
5561 int next_node = find_next_best_node(node, used_nodes);
5563 nodemask = node_to_cpumask(next_node);
5564 cpus_or(span, span, nodemask);
5571 int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
5574 * SMT sched-domains:
5576 #ifdef CONFIG_SCHED_SMT
5577 static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
5578 static DEFINE_PER_CPU(struct sched_group, sched_group_cpus);
5580 static int cpu_to_cpu_group(int cpu, const cpumask_t *cpu_map,
5581 struct sched_group **sg)
5584 *sg = &per_cpu(sched_group_cpus, cpu);
5590 * multi-core sched-domains:
5592 #ifdef CONFIG_SCHED_MC
5593 static DEFINE_PER_CPU(struct sched_domain, core_domains);
5594 static DEFINE_PER_CPU(struct sched_group, sched_group_core);
5597 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
5598 static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map,
5599 struct sched_group **sg)
5602 cpumask_t mask = cpu_sibling_map[cpu];
5603 cpus_and(mask, mask, *cpu_map);
5604 group = first_cpu(mask);
5606 *sg = &per_cpu(sched_group_core, group);
5609 #elif defined(CONFIG_SCHED_MC)
5610 static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map,
5611 struct sched_group **sg)
5614 *sg = &per_cpu(sched_group_core, cpu);
5619 static DEFINE_PER_CPU(struct sched_domain, phys_domains);
5620 static DEFINE_PER_CPU(struct sched_group, sched_group_phys);
5622 static int cpu_to_phys_group(int cpu, const cpumask_t *cpu_map,
5623 struct sched_group **sg)
5626 #ifdef CONFIG_SCHED_MC
5627 cpumask_t mask = cpu_coregroup_map(cpu);
5628 cpus_and(mask, mask, *cpu_map);
5629 group = first_cpu(mask);
5630 #elif defined(CONFIG_SCHED_SMT)
5631 cpumask_t mask = cpu_sibling_map[cpu];
5632 cpus_and(mask, mask, *cpu_map);
5633 group = first_cpu(mask);
5638 *sg = &per_cpu(sched_group_phys, group);
5644 * The init_sched_build_groups can't handle what we want to do with node
5645 * groups, so roll our own. Now each node has its own list of groups which
5646 * gets dynamically allocated.
5648 static DEFINE_PER_CPU(struct sched_domain, node_domains);
5649 static struct sched_group **sched_group_nodes_bycpu[NR_CPUS];
5651 static DEFINE_PER_CPU(struct sched_domain, allnodes_domains);
5652 static DEFINE_PER_CPU(struct sched_group, sched_group_allnodes);
5654 static int cpu_to_allnodes_group(int cpu, const cpumask_t *cpu_map,
5655 struct sched_group **sg)
5657 cpumask_t nodemask = node_to_cpumask(cpu_to_node(cpu));
5660 cpus_and(nodemask, nodemask, *cpu_map);
5661 group = first_cpu(nodemask);
5664 *sg = &per_cpu(sched_group_allnodes, group);
5668 static void init_numa_sched_groups_power(struct sched_group *group_head)
5670 struct sched_group *sg = group_head;
5676 for_each_cpu_mask(j, sg->cpumask) {
5677 struct sched_domain *sd;
5679 sd = &per_cpu(phys_domains, j);
5680 if (j != first_cpu(sd->groups->cpumask)) {
5682 * Only add "power" once for each
5688 sg_inc_cpu_power(sg, sd->groups->__cpu_power);
5691 if (sg != group_head)
5697 /* Free memory allocated for various sched_group structures */
5698 static void free_sched_groups(const cpumask_t *cpu_map)
5702 for_each_cpu_mask(cpu, *cpu_map) {
5703 struct sched_group **sched_group_nodes
5704 = sched_group_nodes_bycpu[cpu];
5706 if (!sched_group_nodes)
5709 for (i = 0; i < MAX_NUMNODES; i++) {
5710 cpumask_t nodemask = node_to_cpumask(i);
5711 struct sched_group *oldsg, *sg = sched_group_nodes[i];
5713 cpus_and(nodemask, nodemask, *cpu_map);
5714 if (cpus_empty(nodemask))
5724 if (oldsg != sched_group_nodes[i])
5727 kfree(sched_group_nodes);
5728 sched_group_nodes_bycpu[cpu] = NULL;
5732 static void free_sched_groups(const cpumask_t *cpu_map)
5738 * Initialize sched groups cpu_power.
5740 * cpu_power indicates the capacity of sched group, which is used while
5741 * distributing the load between different sched groups in a sched domain.
5742 * Typically cpu_power for all the groups in a sched domain will be same unless
5743 * there are asymmetries in the topology. If there are asymmetries, group
5744 * having more cpu_power will pickup more load compared to the group having
5747 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
5748 * the maximum number of tasks a group can handle in the presence of other idle
5749 * or lightly loaded groups in the same sched domain.
5751 static void init_sched_groups_power(int cpu, struct sched_domain *sd)
5753 struct sched_domain *child;
5754 struct sched_group *group;
5756 WARN_ON(!sd || !sd->groups);
5758 if (cpu != first_cpu(sd->groups->cpumask))
5763 sd->groups->__cpu_power = 0;
5766 * For perf policy, if the groups in child domain share resources
5767 * (for example cores sharing some portions of the cache hierarchy
5768 * or SMT), then set this domain groups cpu_power such that each group
5769 * can handle only one task, when there are other idle groups in the
5770 * same sched domain.
5772 if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) &&
5774 (SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) {
5775 sg_inc_cpu_power(sd->groups, SCHED_LOAD_SCALE);
5780 * add cpu_power of each child group to this groups cpu_power
5782 group = child->groups;
5784 sg_inc_cpu_power(sd->groups, group->__cpu_power);
5785 group = group->next;
5786 } while (group != child->groups);
5790 * Build sched domains for a given set of cpus and attach the sched domains
5791 * to the individual cpus
5793 static int build_sched_domains(const cpumask_t *cpu_map)
5797 struct sched_group **sched_group_nodes = NULL;
5798 int sd_allnodes = 0;
5801 * Allocate the per-node list of sched groups
5803 sched_group_nodes = kzalloc(sizeof(struct sched_group *)*MAX_NUMNODES,
5805 if (!sched_group_nodes) {
5806 printk(KERN_WARNING "Can not alloc sched group node list\n");
5809 sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes;
5813 * Set up domains for cpus specified by the cpu_map.
5815 for_each_cpu_mask(i, *cpu_map) {
5816 struct sched_domain *sd = NULL, *p;
5817 cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
5819 cpus_and(nodemask, nodemask, *cpu_map);
5822 if (cpus_weight(*cpu_map) >
5823 SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) {
5824 sd = &per_cpu(allnodes_domains, i);
5825 *sd = SD_ALLNODES_INIT;
5826 sd->span = *cpu_map;
5827 cpu_to_allnodes_group(i, cpu_map, &sd->groups);
5833 sd = &per_cpu(node_domains, i);
5835 sd->span = sched_domain_node_span(cpu_to_node(i));
5839 cpus_and(sd->span, sd->span, *cpu_map);
5843 sd = &per_cpu(phys_domains, i);
5845 sd->span = nodemask;
5849 cpu_to_phys_group(i, cpu_map, &sd->groups);
5851 #ifdef CONFIG_SCHED_MC
5853 sd = &per_cpu(core_domains, i);
5855 sd->span = cpu_coregroup_map(i);
5856 cpus_and(sd->span, sd->span, *cpu_map);
5859 cpu_to_core_group(i, cpu_map, &sd->groups);
5862 #ifdef CONFIG_SCHED_SMT
5864 sd = &per_cpu(cpu_domains, i);
5865 *sd = SD_SIBLING_INIT;
5866 sd->span = cpu_sibling_map[i];
5867 cpus_and(sd->span, sd->span, *cpu_map);
5870 cpu_to_cpu_group(i, cpu_map, &sd->groups);
5874 #ifdef CONFIG_SCHED_SMT
5875 /* Set up CPU (sibling) groups */
5876 for_each_cpu_mask(i, *cpu_map) {
5877 cpumask_t this_sibling_map = cpu_sibling_map[i];
5878 cpus_and(this_sibling_map, this_sibling_map, *cpu_map);
5879 if (i != first_cpu(this_sibling_map))
5882 init_sched_build_groups(this_sibling_map, cpu_map,
5887 #ifdef CONFIG_SCHED_MC
5888 /* Set up multi-core groups */
5889 for_each_cpu_mask(i, *cpu_map) {
5890 cpumask_t this_core_map = cpu_coregroup_map(i);
5891 cpus_and(this_core_map, this_core_map, *cpu_map);
5892 if (i != first_cpu(this_core_map))
5894 init_sched_build_groups(this_core_map, cpu_map,
5895 &cpu_to_core_group);
5899 /* Set up physical groups */
5900 for (i = 0; i < MAX_NUMNODES; i++) {
5901 cpumask_t nodemask = node_to_cpumask(i);
5903 cpus_and(nodemask, nodemask, *cpu_map);
5904 if (cpus_empty(nodemask))
5907 init_sched_build_groups(nodemask, cpu_map, &cpu_to_phys_group);
5911 /* Set up node groups */
5913 init_sched_build_groups(*cpu_map, cpu_map,
5914 &cpu_to_allnodes_group);
5916 for (i = 0; i < MAX_NUMNODES; i++) {
5917 /* Set up node groups */
5918 struct sched_group *sg, *prev;
5919 cpumask_t nodemask = node_to_cpumask(i);
5920 cpumask_t domainspan;
5921 cpumask_t covered = CPU_MASK_NONE;
5924 cpus_and(nodemask, nodemask, *cpu_map);
5925 if (cpus_empty(nodemask)) {
5926 sched_group_nodes[i] = NULL;
5930 domainspan = sched_domain_node_span(i);
5931 cpus_and(domainspan, domainspan, *cpu_map);
5933 sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i);
5935 printk(KERN_WARNING "Can not alloc domain group for "
5939 sched_group_nodes[i] = sg;
5940 for_each_cpu_mask(j, nodemask) {
5941 struct sched_domain *sd;
5943 sd = &per_cpu(node_domains, j);
5946 sg->__cpu_power = 0;
5947 sg->cpumask = nodemask;
5949 cpus_or(covered, covered, nodemask);
5952 for (j = 0; j < MAX_NUMNODES; j++) {
5953 cpumask_t tmp, notcovered;
5954 int n = (i + j) % MAX_NUMNODES;
5956 cpus_complement(notcovered, covered);
5957 cpus_and(tmp, notcovered, *cpu_map);
5958 cpus_and(tmp, tmp, domainspan);
5959 if (cpus_empty(tmp))
5962 nodemask = node_to_cpumask(n);
5963 cpus_and(tmp, tmp, nodemask);
5964 if (cpus_empty(tmp))
5967 sg = kmalloc_node(sizeof(struct sched_group),
5971 "Can not alloc domain group for node %d\n", j);
5974 sg->__cpu_power = 0;
5976 sg->next = prev->next;
5977 cpus_or(covered, covered, tmp);
5984 /* Calculate CPU power for physical packages and nodes */
5985 #ifdef CONFIG_SCHED_SMT
5986 for_each_cpu_mask(i, *cpu_map) {
5987 struct sched_domain *sd = &per_cpu(cpu_domains, i);
5989 init_sched_groups_power(i, sd);
5992 #ifdef CONFIG_SCHED_MC
5993 for_each_cpu_mask(i, *cpu_map) {
5994 struct sched_domain *sd = &per_cpu(core_domains, i);
5996 init_sched_groups_power(i, sd);
6000 for_each_cpu_mask(i, *cpu_map) {
6001 struct sched_domain *sd = &per_cpu(phys_domains, i);
6003 init_sched_groups_power(i, sd);
6007 for (i = 0; i < MAX_NUMNODES; i++)
6008 init_numa_sched_groups_power(sched_group_nodes[i]);
6011 struct sched_group *sg;
6013 cpu_to_allnodes_group(first_cpu(*cpu_map), cpu_map, &sg);
6014 init_numa_sched_groups_power(sg);
6018 /* Attach the domains */
6019 for_each_cpu_mask(i, *cpu_map) {
6020 struct sched_domain *sd;
6021 #ifdef CONFIG_SCHED_SMT
6022 sd = &per_cpu(cpu_domains, i);
6023 #elif defined(CONFIG_SCHED_MC)
6024 sd = &per_cpu(core_domains, i);
6026 sd = &per_cpu(phys_domains, i);
6028 cpu_attach_domain(sd, i);
6035 free_sched_groups(cpu_map);
6040 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6042 static int arch_init_sched_domains(const cpumask_t *cpu_map)
6044 cpumask_t cpu_default_map;
6048 * Setup mask for cpus without special case scheduling requirements.
6049 * For now this just excludes isolated cpus, but could be used to
6050 * exclude other special cases in the future.
6052 cpus_andnot(cpu_default_map, *cpu_map, cpu_isolated_map);
6054 err = build_sched_domains(&cpu_default_map);
6059 static void arch_destroy_sched_domains(const cpumask_t *cpu_map)
6061 free_sched_groups(cpu_map);
6065 * Detach sched domains from a group of cpus specified in cpu_map
6066 * These cpus will now be attached to the NULL domain
6068 static void detach_destroy_domains(const cpumask_t *cpu_map)
6072 for_each_cpu_mask(i, *cpu_map)
6073 cpu_attach_domain(NULL, i);
6074 synchronize_sched();
6075 arch_destroy_sched_domains(cpu_map);
6079 * Partition sched domains as specified by the cpumasks below.
6080 * This attaches all cpus from the cpumasks to the NULL domain,
6081 * waits for a RCU quiescent period, recalculates sched
6082 * domain information and then attaches them back to the
6083 * correct sched domains
6084 * Call with hotplug lock held
6086 int partition_sched_domains(cpumask_t *partition1, cpumask_t *partition2)
6088 cpumask_t change_map;
6091 cpus_and(*partition1, *partition1, cpu_online_map);
6092 cpus_and(*partition2, *partition2, cpu_online_map);
6093 cpus_or(change_map, *partition1, *partition2);
6095 /* Detach sched domains from all of the affected cpus */
6096 detach_destroy_domains(&change_map);
6097 if (!cpus_empty(*partition1))
6098 err = build_sched_domains(partition1);
6099 if (!err && !cpus_empty(*partition2))
6100 err = build_sched_domains(partition2);
6105 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6106 int arch_reinit_sched_domains(void)
6110 mutex_lock(&sched_hotcpu_mutex);
6111 detach_destroy_domains(&cpu_online_map);
6112 err = arch_init_sched_domains(&cpu_online_map);
6113 mutex_unlock(&sched_hotcpu_mutex);
6118 static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
6122 if (buf[0] != '0' && buf[0] != '1')
6126 sched_smt_power_savings = (buf[0] == '1');
6128 sched_mc_power_savings = (buf[0] == '1');
6130 ret = arch_reinit_sched_domains();
6132 return ret ? ret : count;
6135 int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
6139 #ifdef CONFIG_SCHED_SMT
6141 err = sysfs_create_file(&cls->kset.kobj,
6142 &attr_sched_smt_power_savings.attr);
6144 #ifdef CONFIG_SCHED_MC
6145 if (!err && mc_capable())
6146 err = sysfs_create_file(&cls->kset.kobj,
6147 &attr_sched_mc_power_savings.attr);
6153 #ifdef CONFIG_SCHED_MC
6154 static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page)
6156 return sprintf(page, "%u\n", sched_mc_power_savings);
6158 static ssize_t sched_mc_power_savings_store(struct sys_device *dev,
6159 const char *buf, size_t count)
6161 return sched_power_savings_store(buf, count, 0);
6163 SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
6164 sched_mc_power_savings_store);
6167 #ifdef CONFIG_SCHED_SMT
6168 static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page)
6170 return sprintf(page, "%u\n", sched_smt_power_savings);
6172 static ssize_t sched_smt_power_savings_store(struct sys_device *dev,
6173 const char *buf, size_t count)
6175 return sched_power_savings_store(buf, count, 1);
6177 SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
6178 sched_smt_power_savings_store);
6182 * Force a reinitialization of the sched domains hierarchy. The domains
6183 * and groups cannot be updated in place without racing with the balancing
6184 * code, so we temporarily attach all running cpus to the NULL domain
6185 * which will prevent rebalancing while the sched domains are recalculated.
6187 static int update_sched_domains(struct notifier_block *nfb,
6188 unsigned long action, void *hcpu)
6191 case CPU_UP_PREPARE:
6192 case CPU_UP_PREPARE_FROZEN:
6193 case CPU_DOWN_PREPARE:
6194 case CPU_DOWN_PREPARE_FROZEN:
6195 detach_destroy_domains(&cpu_online_map);
6198 case CPU_UP_CANCELED:
6199 case CPU_UP_CANCELED_FROZEN:
6200 case CPU_DOWN_FAILED:
6201 case CPU_DOWN_FAILED_FROZEN:
6203 case CPU_ONLINE_FROZEN:
6205 case CPU_DEAD_FROZEN:
6207 * Fall through and re-initialise the domains.
6214 /* The hotplug lock is already held by cpu_up/cpu_down */
6215 arch_init_sched_domains(&cpu_online_map);
6220 void __init sched_init_smp(void)
6222 cpumask_t non_isolated_cpus;
6224 mutex_lock(&sched_hotcpu_mutex);
6225 arch_init_sched_domains(&cpu_online_map);
6226 cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
6227 if (cpus_empty(non_isolated_cpus))
6228 cpu_set(smp_processor_id(), non_isolated_cpus);
6229 mutex_unlock(&sched_hotcpu_mutex);
6230 /* XXX: Theoretical race here - CPU may be hotplugged now */
6231 hotcpu_notifier(update_sched_domains, 0);
6233 /* Move init over to a non-isolated CPU */
6234 if (set_cpus_allowed(current, non_isolated_cpus) < 0)
6236 sched_init_granularity();
6239 void __init sched_init_smp(void)
6241 sched_init_granularity();
6243 #endif /* CONFIG_SMP */
6245 int in_sched_functions(unsigned long addr)
6247 /* Linker adds these: start and end of __sched functions */
6248 extern char __sched_text_start[], __sched_text_end[];
6250 return in_lock_functions(addr) ||
6251 (addr >= (unsigned long)__sched_text_start
6252 && addr < (unsigned long)__sched_text_end);
6255 static inline void init_cfs_rq(struct cfs_rq *cfs_rq, struct rq *rq)
6257 cfs_rq->tasks_timeline = RB_ROOT;
6258 cfs_rq->fair_clock = 1;
6259 #ifdef CONFIG_FAIR_GROUP_SCHED
6264 void __init sched_init(void)
6266 u64 now = sched_clock();
6267 int highest_cpu = 0;
6271 * Link up the scheduling class hierarchy:
6273 rt_sched_class.next = &fair_sched_class;
6274 fair_sched_class.next = &idle_sched_class;
6275 idle_sched_class.next = NULL;
6277 for_each_possible_cpu(i) {
6278 struct rt_prio_array *array;
6282 spin_lock_init(&rq->lock);
6283 lockdep_set_class(&rq->lock, &rq->rq_lock_key);
6286 init_cfs_rq(&rq->cfs, rq);
6287 #ifdef CONFIG_FAIR_GROUP_SCHED
6288 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
6289 list_add(&rq->cfs.leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
6291 rq->ls.load_update_last = now;
6292 rq->ls.load_update_start = now;
6294 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
6295 rq->cpu_load[j] = 0;
6298 rq->active_balance = 0;
6299 rq->next_balance = jiffies;
6302 rq->migration_thread = NULL;
6303 INIT_LIST_HEAD(&rq->migration_queue);
6305 atomic_set(&rq->nr_iowait, 0);
6307 array = &rq->rt.active;
6308 for (j = 0; j < MAX_RT_PRIO; j++) {
6309 INIT_LIST_HEAD(array->queue + j);
6310 __clear_bit(j, array->bitmap);
6313 /* delimiter for bitsearch: */
6314 __set_bit(MAX_RT_PRIO, array->bitmap);
6317 set_load_weight(&init_task);
6320 nr_cpu_ids = highest_cpu + 1;
6321 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL);
6324 #ifdef CONFIG_RT_MUTEXES
6325 plist_head_init(&init_task.pi_waiters, &init_task.pi_lock);
6329 * The boot idle thread does lazy MMU switching as well:
6331 atomic_inc(&init_mm.mm_count);
6332 enter_lazy_tlb(&init_mm, current);
6335 * Make us the idle thread. Technically, schedule() should not be
6336 * called from this thread, however somewhere below it might be,
6337 * but because we are the idle thread, we just pick up running again
6338 * when this runqueue becomes "idle".
6340 init_idle(current, smp_processor_id());
6342 * During early bootup we pretend to be a normal task:
6344 current->sched_class = &fair_sched_class;
6347 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6348 void __might_sleep(char *file, int line)
6351 static unsigned long prev_jiffy; /* ratelimiting */
6353 if ((in_atomic() || irqs_disabled()) &&
6354 system_state == SYSTEM_RUNNING && !oops_in_progress) {
6355 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
6357 prev_jiffy = jiffies;
6358 printk(KERN_ERR "BUG: sleeping function called from invalid"
6359 " context at %s:%d\n", file, line);
6360 printk("in_atomic():%d, irqs_disabled():%d\n",
6361 in_atomic(), irqs_disabled());
6362 debug_show_held_locks(current);
6363 if (irqs_disabled())
6364 print_irqtrace_events(current);
6369 EXPORT_SYMBOL(__might_sleep);
6372 #ifdef CONFIG_MAGIC_SYSRQ
6373 void normalize_rt_tasks(void)
6375 struct task_struct *g, *p;
6376 unsigned long flags;
6380 read_lock_irq(&tasklist_lock);
6381 do_each_thread(g, p) {
6383 p->se.wait_runtime = 0;
6384 p->se.wait_start_fair = 0;
6385 p->se.wait_start = 0;
6386 p->se.exec_start = 0;
6387 p->se.sleep_start = 0;
6388 p->se.sleep_start_fair = 0;
6389 p->se.block_start = 0;
6390 task_rq(p)->cfs.fair_clock = 0;
6391 task_rq(p)->clock = 0;
6395 * Renice negative nice level userspace
6398 if (TASK_NICE(p) < 0 && p->mm)
6399 set_user_nice(p, 0);
6403 spin_lock_irqsave(&p->pi_lock, flags);
6404 rq = __task_rq_lock(p);
6407 * Do not touch the migration thread:
6409 if (p == rq->migration_thread)
6413 on_rq = p->se.on_rq;
6415 deactivate_task(task_rq(p), p, 0);
6416 __setscheduler(rq, p, SCHED_NORMAL, 0);
6418 activate_task(task_rq(p), p, 0);
6419 resched_task(rq->curr);
6424 __task_rq_unlock(rq);
6425 spin_unlock_irqrestore(&p->pi_lock, flags);
6426 } while_each_thread(g, p);
6428 read_unlock_irq(&tasklist_lock);
6431 #endif /* CONFIG_MAGIC_SYSRQ */
6435 * These functions are only useful for the IA64 MCA handling.
6437 * They can only be called when the whole system has been
6438 * stopped - every CPU needs to be quiescent, and no scheduling
6439 * activity can take place. Using them for anything else would
6440 * be a serious bug, and as a result, they aren't even visible
6441 * under any other configuration.
6445 * curr_task - return the current task for a given cpu.
6446 * @cpu: the processor in question.
6448 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6450 struct task_struct *curr_task(int cpu)
6452 return cpu_curr(cpu);
6456 * set_curr_task - set the current task for a given cpu.
6457 * @cpu: the processor in question.
6458 * @p: the task pointer to set.
6460 * Description: This function must only be used when non-maskable interrupts
6461 * are serviced on a separate stack. It allows the architecture to switch the
6462 * notion of the current task on a cpu in a non-blocking manner. This function
6463 * must be called with all CPU's synchronized, and interrupts disabled, the
6464 * and caller must save the original value of the current task (see
6465 * curr_task() above) and restore that value before reenabling interrupts and
6466 * re-starting the system.
6468 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6470 void set_curr_task(int cpu, struct task_struct *p)