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
22 #include <linux/module.h>
23 #include <linux/nmi.h>
24 #include <linux/init.h>
25 #include <asm/uaccess.h>
26 #include <linux/highmem.h>
27 #include <linux/smp_lock.h>
28 #include <asm/mmu_context.h>
29 #include <linux/interrupt.h>
30 #include <linux/capability.h>
31 #include <linux/completion.h>
32 #include <linux/kernel_stat.h>
33 #include <linux/debug_locks.h>
34 #include <linux/security.h>
35 #include <linux/notifier.h>
36 #include <linux/profile.h>
37 #include <linux/freezer.h>
38 #include <linux/vmalloc.h>
39 #include <linux/blkdev.h>
40 #include <linux/delay.h>
41 #include <linux/smp.h>
42 #include <linux/threads.h>
43 #include <linux/timer.h>
44 #include <linux/rcupdate.h>
45 #include <linux/cpu.h>
46 #include <linux/cpuset.h>
47 #include <linux/percpu.h>
48 #include <linux/kthread.h>
49 #include <linux/seq_file.h>
50 #include <linux/syscalls.h>
51 #include <linux/times.h>
52 #include <linux/tsacct_kern.h>
53 #include <linux/kprobes.h>
54 #include <linux/delayacct.h>
55 #include <linux/reciprocal_div.h>
58 #include <asm/unistd.h>
61 * Scheduler clock - returns current time in nanosec units.
62 * This is default implementation.
63 * Architectures and sub-architectures can override this.
65 unsigned long long __attribute__((weak)) sched_clock(void)
67 return (unsigned long long)jiffies * (1000000000 / HZ);
71 * Convert user-nice values [ -20 ... 0 ... 19 ]
72 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
75 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
76 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
77 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
80 * 'User priority' is the nice value converted to something we
81 * can work with better when scaling various scheduler parameters,
82 * it's a [ 0 ... 39 ] range.
84 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
85 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
86 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
89 * Some helpers for converting nanosecond timing to jiffy resolution
91 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
92 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
94 #define NICE_0_LOAD SCHED_LOAD_SCALE
95 #define NICE_0_SHIFT SCHED_LOAD_SHIFT
98 * These are the 'tuning knobs' of the scheduler:
100 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
101 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
102 * Timeslices get refilled after they expire.
104 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
105 #define DEF_TIMESLICE (100 * HZ / 1000)
106 #define ON_RUNQUEUE_WEIGHT 30
107 #define CHILD_PENALTY 95
108 #define PARENT_PENALTY 100
109 #define EXIT_WEIGHT 3
110 #define PRIO_BONUS_RATIO 25
111 #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
112 #define INTERACTIVE_DELTA 2
113 #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
114 #define STARVATION_LIMIT (MAX_SLEEP_AVG)
115 #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
118 * If a task is 'interactive' then we reinsert it in the active
119 * array after it has expired its current timeslice. (it will not
120 * continue to run immediately, it will still roundrobin with
121 * other interactive tasks.)
123 * This part scales the interactivity limit depending on niceness.
125 * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
126 * Here are a few examples of different nice levels:
128 * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
129 * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
130 * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
131 * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
132 * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
134 * (the X axis represents the possible -5 ... 0 ... +5 dynamic
135 * priority range a task can explore, a value of '1' means the
136 * task is rated interactive.)
138 * Ie. nice +19 tasks can never get 'interactive' enough to be
139 * reinserted into the active array. And only heavily CPU-hog nice -20
140 * tasks will be expired. Default nice 0 tasks are somewhere between,
141 * it takes some effort for them to get interactive, but it's not
145 #define CURRENT_BONUS(p) \
146 (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
149 #define GRANULARITY (10 * HZ / 1000 ? : 1)
152 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
153 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
156 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
157 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
160 #define SCALE(v1,v1_max,v2_max) \
161 (v1) * (v2_max) / (v1_max)
164 (SCALE(TASK_NICE(p) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \
167 #define TASK_INTERACTIVE(p) \
168 ((p)->prio <= (p)->static_prio - DELTA(p))
170 #define INTERACTIVE_SLEEP(p) \
171 (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
172 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
174 #define TASK_PREEMPTS_CURR(p, rq) \
175 ((p)->prio < (rq)->curr->prio)
177 #define SCALE_PRIO(x, prio) \
178 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
180 static unsigned int static_prio_timeslice(int static_prio)
182 if (static_prio < NICE_TO_PRIO(0))
183 return SCALE_PRIO(DEF_TIMESLICE * 4, static_prio);
185 return SCALE_PRIO(DEF_TIMESLICE, static_prio);
190 * Divide a load by a sched group cpu_power : (load / sg->__cpu_power)
191 * Since cpu_power is a 'constant', we can use a reciprocal divide.
193 static inline u32 sg_div_cpu_power(const struct sched_group *sg, u32 load)
195 return reciprocal_divide(load, sg->reciprocal_cpu_power);
199 * Each time a sched group cpu_power is changed,
200 * we must compute its reciprocal value
202 static inline void sg_inc_cpu_power(struct sched_group *sg, u32 val)
204 sg->__cpu_power += val;
205 sg->reciprocal_cpu_power = reciprocal_value(sg->__cpu_power);
210 * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
211 * to time slice values: [800ms ... 100ms ... 5ms]
213 * The higher a thread's priority, the bigger timeslices
214 * it gets during one round of execution. But even the lowest
215 * priority thread gets MIN_TIMESLICE worth of execution time.
218 static inline unsigned int task_timeslice(struct task_struct *p)
220 return static_prio_timeslice(p->static_prio);
223 static inline int rt_policy(int policy)
225 if (unlikely(policy == SCHED_FIFO) || unlikely(policy == SCHED_RR))
230 static inline int task_has_rt_policy(struct task_struct *p)
232 return rt_policy(p->policy);
236 * This is the priority-queue data structure of the RT scheduling class:
238 struct rt_prio_array {
239 DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
240 struct list_head queue[MAX_RT_PRIO];
244 struct load_weight load;
245 u64 load_update_start, load_update_last;
246 unsigned long delta_fair, delta_exec, delta_stat;
249 /* CFS-related fields in a runqueue */
251 struct load_weight load;
252 unsigned long nr_running;
258 unsigned long wait_runtime_overruns, wait_runtime_underruns;
260 struct rb_root tasks_timeline;
261 struct rb_node *rb_leftmost;
262 struct rb_node *rb_load_balance_curr;
263 #ifdef CONFIG_FAIR_GROUP_SCHED
264 /* 'curr' points to currently running entity on this cfs_rq.
265 * It is set to NULL otherwise (i.e when none are currently running).
267 struct sched_entity *curr;
268 struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
270 /* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
271 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
272 * (like users, containers etc.)
274 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
275 * list is used during load balance.
277 struct list_head leaf_cfs_rq_list; /* Better name : task_cfs_rq_list? */
281 /* Real-Time classes' related field in a runqueue: */
283 struct rt_prio_array active;
284 int rt_load_balance_idx;
285 struct list_head *rt_load_balance_head, *rt_load_balance_curr;
289 * The prio-array type of the old scheduler:
292 unsigned int nr_active;
293 DECLARE_BITMAP(bitmap, MAX_PRIO+1); /* include 1 bit for delimiter */
294 struct list_head queue[MAX_PRIO];
298 * This is the main, per-CPU runqueue data structure.
300 * Locking rule: those places that want to lock multiple runqueues
301 * (such as the load balancing or the thread migration code), lock
302 * acquire operations must be ordered by ascending &runqueue.
305 spinlock_t lock; /* runqueue lock */
308 * nr_running and cpu_load should be in the same cacheline because
309 * remote CPUs use both these fields when doing load calculation.
311 unsigned long nr_running;
312 unsigned long raw_weighted_load;
313 #define CPU_LOAD_IDX_MAX 5
314 unsigned long cpu_load[CPU_LOAD_IDX_MAX];
315 unsigned char idle_at_tick;
317 unsigned char in_nohz_recently;
319 struct load_stat ls; /* capture load from *all* tasks on this cpu */
320 unsigned long nr_load_updates;
324 #ifdef CONFIG_FAIR_GROUP_SCHED
325 struct list_head leaf_cfs_rq_list; /* list of leaf cfs_rq on this cpu */
330 * This is part of a global counter where only the total sum
331 * over all CPUs matters. A task can increase this counter on
332 * one CPU and if it got migrated afterwards it may decrease
333 * it on another CPU. Always updated under the runqueue lock:
335 unsigned long nr_uninterruptible;
337 unsigned long expired_timestamp;
338 unsigned long long most_recent_timestamp;
340 struct task_struct *curr, *idle;
341 unsigned long next_balance;
342 struct mm_struct *prev_mm;
344 struct prio_array *active, *expired, arrays[2];
345 int best_expired_prio;
347 u64 clock, prev_clock_raw;
350 unsigned int clock_warps, clock_overflows;
351 unsigned int clock_unstable_events;
353 struct sched_class *load_balance_class;
358 struct sched_domain *sd;
360 /* For active balancing */
363 int cpu; /* cpu of this runqueue */
365 struct task_struct *migration_thread;
366 struct list_head migration_queue;
369 #ifdef CONFIG_SCHEDSTATS
371 struct sched_info rq_sched_info;
373 /* sys_sched_yield() stats */
374 unsigned long yld_exp_empty;
375 unsigned long yld_act_empty;
376 unsigned long yld_both_empty;
377 unsigned long yld_cnt;
379 /* schedule() stats */
380 unsigned long sched_switch;
381 unsigned long sched_cnt;
382 unsigned long sched_goidle;
384 /* try_to_wake_up() stats */
385 unsigned long ttwu_cnt;
386 unsigned long ttwu_local;
388 struct lock_class_key rq_lock_key;
391 static DEFINE_PER_CPU(struct rq, runqueues) ____cacheline_aligned_in_smp;
392 static DEFINE_MUTEX(sched_hotcpu_mutex);
394 static inline int cpu_of(struct rq *rq)
404 * Per-runqueue clock, as finegrained as the platform can give us:
406 static unsigned long long __rq_clock(struct rq *rq)
408 u64 prev_raw = rq->prev_clock_raw;
409 u64 now = sched_clock();
410 s64 delta = now - prev_raw;
411 u64 clock = rq->clock;
414 * Protect against sched_clock() occasionally going backwards:
416 if (unlikely(delta < 0)) {
421 * Catch too large forward jumps too:
423 if (unlikely(delta > 2*TICK_NSEC)) {
425 rq->clock_overflows++;
427 if (unlikely(delta > rq->clock_max_delta))
428 rq->clock_max_delta = delta;
433 rq->prev_clock_raw = now;
439 static inline unsigned long long rq_clock(struct rq *rq)
441 int this_cpu = smp_processor_id();
443 if (this_cpu == cpu_of(rq))
444 return __rq_clock(rq);
450 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
451 * See detach_destroy_domains: synchronize_sched for details.
453 * The domain tree of any CPU may only be accessed from within
454 * preempt-disabled sections.
456 #define for_each_domain(cpu, __sd) \
457 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
459 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
460 #define this_rq() (&__get_cpu_var(runqueues))
461 #define task_rq(p) cpu_rq(task_cpu(p))
462 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
464 #ifdef CONFIG_FAIR_GROUP_SCHED
465 /* Change a task's ->cfs_rq if it moves across CPUs */
466 static inline void set_task_cfs_rq(struct task_struct *p)
468 p->se.cfs_rq = &task_rq(p)->cfs;
471 static inline void set_task_cfs_rq(struct task_struct *p)
476 #ifndef prepare_arch_switch
477 # define prepare_arch_switch(next) do { } while (0)
479 #ifndef finish_arch_switch
480 # define finish_arch_switch(prev) do { } while (0)
483 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
484 static inline int task_running(struct rq *rq, struct task_struct *p)
486 return rq->curr == p;
489 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
493 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
495 #ifdef CONFIG_DEBUG_SPINLOCK
496 /* this is a valid case when another task releases the spinlock */
497 rq->lock.owner = current;
500 * If we are tracking spinlock dependencies then we have to
501 * fix up the runqueue lock - which gets 'carried over' from
504 spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
506 spin_unlock_irq(&rq->lock);
509 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
510 static inline int task_running(struct rq *rq, struct task_struct *p)
515 return rq->curr == p;
519 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
523 * We can optimise this out completely for !SMP, because the
524 * SMP rebalancing from interrupt is the only thing that cares
529 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
530 spin_unlock_irq(&rq->lock);
532 spin_unlock(&rq->lock);
536 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
540 * After ->oncpu is cleared, the task can be moved to a different CPU.
541 * We must ensure this doesn't happen until the switch is completely
547 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
551 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
554 * __task_rq_lock - lock the runqueue a given task resides on.
555 * Must be called interrupts disabled.
557 static inline struct rq *__task_rq_lock(struct task_struct *p)
564 spin_lock(&rq->lock);
565 if (unlikely(rq != task_rq(p))) {
566 spin_unlock(&rq->lock);
567 goto repeat_lock_task;
573 * task_rq_lock - lock the runqueue a given task resides on and disable
574 * interrupts. Note the ordering: we can safely lookup the task_rq without
575 * explicitly disabling preemption.
577 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
583 local_irq_save(*flags);
585 spin_lock(&rq->lock);
586 if (unlikely(rq != task_rq(p))) {
587 spin_unlock_irqrestore(&rq->lock, *flags);
588 goto repeat_lock_task;
593 static inline void __task_rq_unlock(struct rq *rq)
596 spin_unlock(&rq->lock);
599 static inline void task_rq_unlock(struct rq *rq, unsigned long *flags)
602 spin_unlock_irqrestore(&rq->lock, *flags);
606 * this_rq_lock - lock this runqueue and disable interrupts.
608 static inline struct rq *this_rq_lock(void)
615 spin_lock(&rq->lock);
621 * resched_task - mark a task 'to be rescheduled now'.
623 * On UP this means the setting of the need_resched flag, on SMP it
624 * might also involve a cross-CPU call to trigger the scheduler on
629 #ifndef tsk_is_polling
630 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
633 static void resched_task(struct task_struct *p)
637 assert_spin_locked(&task_rq(p)->lock);
639 if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED)))
642 set_tsk_thread_flag(p, TIF_NEED_RESCHED);
645 if (cpu == smp_processor_id())
648 /* NEED_RESCHED must be visible before we test polling */
650 if (!tsk_is_polling(p))
651 smp_send_reschedule(cpu);
654 static void resched_cpu(int cpu)
656 struct rq *rq = cpu_rq(cpu);
659 if (!spin_trylock_irqsave(&rq->lock, flags))
661 resched_task(cpu_curr(cpu));
662 spin_unlock_irqrestore(&rq->lock, flags);
665 static inline void resched_task(struct task_struct *p)
667 assert_spin_locked(&task_rq(p)->lock);
668 set_tsk_need_resched(p);
672 #include "sched_stats.h"
674 static u64 div64_likely32(u64 divident, unsigned long divisor)
676 #if BITS_PER_LONG == 32
677 if (likely(divident <= 0xffffffffULL))
678 return (u32)divident / divisor;
679 do_div(divident, divisor);
683 return divident / divisor;
687 #if BITS_PER_LONG == 32
688 # define WMULT_CONST (~0UL)
690 # define WMULT_CONST (1UL << 32)
693 #define WMULT_SHIFT 32
695 static inline unsigned long
696 calc_delta_mine(unsigned long delta_exec, unsigned long weight,
697 struct load_weight *lw)
701 if (unlikely(!lw->inv_weight))
702 lw->inv_weight = WMULT_CONST / lw->weight;
704 tmp = (u64)delta_exec * weight;
706 * Check whether we'd overflow the 64-bit multiplication:
708 if (unlikely(tmp > WMULT_CONST)) {
709 tmp = ((tmp >> WMULT_SHIFT/2) * lw->inv_weight)
712 tmp = (tmp * lw->inv_weight) >> WMULT_SHIFT;
715 return (unsigned long)min(tmp, (u64)sysctl_sched_runtime_limit);
718 static inline unsigned long
719 calc_delta_fair(unsigned long delta_exec, struct load_weight *lw)
721 return calc_delta_mine(delta_exec, NICE_0_LOAD, lw);
724 static void update_load_add(struct load_weight *lw, unsigned long inc)
730 static void update_load_sub(struct load_weight *lw, unsigned long dec)
736 static void __update_curr_load(struct rq *rq, struct load_stat *ls)
738 if (rq->curr != rq->idle && ls->load.weight) {
739 ls->delta_exec += ls->delta_stat;
740 ls->delta_fair += calc_delta_fair(ls->delta_stat, &ls->load);
746 * Update delta_exec, delta_fair fields for rq.
748 * delta_fair clock advances at a rate inversely proportional to
749 * total load (rq->ls.load.weight) on the runqueue, while
750 * delta_exec advances at the same rate as wall-clock (provided
753 * delta_exec / delta_fair is a measure of the (smoothened) load on this
754 * runqueue over any given interval. This (smoothened) load is used
755 * during load balance.
757 * This function is called /before/ updating rq->ls.load
758 * and when switching tasks.
760 static void update_curr_load(struct rq *rq, u64 now)
762 struct load_stat *ls = &rq->ls;
765 start = ls->load_update_start;
766 ls->load_update_start = now;
767 ls->delta_stat += now - start;
769 * Stagger updates to ls->delta_fair. Very frequent updates
772 if (ls->delta_stat >= sysctl_sched_stat_granularity)
773 __update_curr_load(rq, ls);
777 * To aid in avoiding the subversion of "niceness" due to uneven distribution
778 * of tasks with abnormal "nice" values across CPUs the contribution that
779 * each task makes to its run queue's load is weighted according to its
780 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
781 * scaled version of the new time slice allocation that they receive on time
786 * Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
787 * If static_prio_timeslice() is ever changed to break this assumption then
788 * this code will need modification
790 #define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
791 #define LOAD_WEIGHT(lp) \
792 (((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
793 #define PRIO_TO_LOAD_WEIGHT(prio) \
794 LOAD_WEIGHT(static_prio_timeslice(prio))
795 #define RTPRIO_TO_LOAD_WEIGHT(rp) \
796 (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
799 inc_raw_weighted_load(struct rq *rq, const struct task_struct *p)
801 rq->raw_weighted_load += p->load_weight;
805 dec_raw_weighted_load(struct rq *rq, const struct task_struct *p)
807 rq->raw_weighted_load -= p->load_weight;
810 static inline void inc_nr_running(struct task_struct *p, struct rq *rq)
813 inc_raw_weighted_load(rq, p);
816 static inline void dec_nr_running(struct task_struct *p, struct rq *rq)
819 dec_raw_weighted_load(rq, p);
822 static void set_load_weight(struct task_struct *p)
824 if (task_has_rt_policy(p)) {
826 if (p == task_rq(p)->migration_thread)
828 * The migration thread does the actual balancing.
829 * Giving its load any weight will skew balancing
835 p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
837 p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
841 * Adding/removing a task to/from a priority array:
843 static void dequeue_task(struct task_struct *p, struct prio_array *array)
846 list_del(&p->run_list);
847 if (list_empty(array->queue + p->prio))
848 __clear_bit(p->prio, array->bitmap);
851 static void enqueue_task(struct task_struct *p, struct prio_array *array)
853 sched_info_queued(p);
854 list_add_tail(&p->run_list, array->queue + p->prio);
855 __set_bit(p->prio, array->bitmap);
861 * Put task to the end of the run list without the overhead of dequeue
862 * followed by enqueue.
864 static void requeue_task(struct task_struct *p, struct prio_array *array)
866 list_move_tail(&p->run_list, array->queue + p->prio);
870 enqueue_task_head(struct task_struct *p, struct prio_array *array)
872 list_add(&p->run_list, array->queue + p->prio);
873 __set_bit(p->prio, array->bitmap);
879 * __normal_prio - return the priority that is based on the static
880 * priority but is modified by bonuses/penalties.
882 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
883 * into the -5 ... 0 ... +5 bonus/penalty range.
885 * We use 25% of the full 0...39 priority range so that:
887 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
888 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
890 * Both properties are important to certain workloads.
893 static inline int __normal_prio(struct task_struct *p)
897 bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
899 prio = p->static_prio - bonus;
900 if (prio < MAX_RT_PRIO)
902 if (prio > MAX_PRIO-1)
908 * Calculate the expected normal priority: i.e. priority
909 * without taking RT-inheritance into account. Might be
910 * boosted by interactivity modifiers. Changes upon fork,
911 * setprio syscalls, and whenever the interactivity
912 * estimator recalculates.
914 static inline int normal_prio(struct task_struct *p)
918 if (task_has_rt_policy(p))
919 prio = MAX_RT_PRIO-1 - p->rt_priority;
921 prio = __normal_prio(p);
926 * Calculate the current priority, i.e. the priority
927 * taken into account by the scheduler. This value might
928 * be boosted by RT tasks, or might be boosted by
929 * interactivity modifiers. Will be RT if the task got
930 * RT-boosted. If not then it returns p->normal_prio.
932 static int effective_prio(struct task_struct *p)
934 p->normal_prio = normal_prio(p);
936 * If we are RT tasks or we were boosted to RT priority,
937 * keep the priority unchanged. Otherwise, update priority
938 * to the normal priority:
940 if (!rt_prio(p->prio))
941 return p->normal_prio;
946 * __activate_task - move a task to the runqueue.
948 static void __activate_task(struct task_struct *p, struct rq *rq)
950 struct prio_array *target = rq->active;
953 target = rq->expired;
954 enqueue_task(p, target);
955 inc_nr_running(p, rq);
959 * __activate_idle_task - move idle task to the _front_ of runqueue.
961 static inline void __activate_idle_task(struct task_struct *p, struct rq *rq)
963 enqueue_task_head(p, rq->active);
964 inc_nr_running(p, rq);
968 * Recalculate p->normal_prio and p->prio after having slept,
969 * updating the sleep-average too:
971 static int recalc_task_prio(struct task_struct *p, unsigned long long now)
973 /* Caller must always ensure 'now >= p->timestamp' */
974 unsigned long sleep_time = now - p->timestamp;
979 if (likely(sleep_time > 0)) {
981 * This ceiling is set to the lowest priority that would allow
982 * a task to be reinserted into the active array on timeslice
985 unsigned long ceiling = INTERACTIVE_SLEEP(p);
987 if (p->mm && sleep_time > ceiling && p->sleep_avg < ceiling) {
989 * Prevents user tasks from achieving best priority
990 * with one single large enough sleep.
992 p->sleep_avg = ceiling;
995 * This code gives a bonus to interactive tasks.
997 * The boost works by updating the 'average sleep time'
998 * value here, based on ->timestamp. The more time a
999 * task spends sleeping, the higher the average gets -
1000 * and the higher the priority boost gets as well.
1002 p->sleep_avg += sleep_time;
1005 if (p->sleep_avg > NS_MAX_SLEEP_AVG)
1006 p->sleep_avg = NS_MAX_SLEEP_AVG;
1009 return effective_prio(p);
1013 * activate_task - move a task to the runqueue and do priority recalculation
1015 * Update all the scheduling statistics stuff. (sleep average
1016 * calculation, priority modifiers, etc.)
1018 static void activate_task(struct task_struct *p, struct rq *rq, int local)
1020 unsigned long long now;
1025 now = sched_clock();
1028 /* Compensate for drifting sched_clock */
1029 struct rq *this_rq = this_rq();
1030 now = (now - this_rq->most_recent_timestamp)
1031 + rq->most_recent_timestamp;
1036 * Sleep time is in units of nanosecs, so shift by 20 to get a
1037 * milliseconds-range estimation of the amount of time that the task
1040 if (unlikely(prof_on == SLEEP_PROFILING)) {
1041 if (p->state == TASK_UNINTERRUPTIBLE)
1042 profile_hits(SLEEP_PROFILING, (void *)get_wchan(p),
1043 (now - p->timestamp) >> 20);
1046 p->prio = recalc_task_prio(p, now);
1049 __activate_task(p, rq);
1053 * deactivate_task - remove a task from the runqueue.
1055 static void deactivate_task(struct task_struct *p, struct rq *rq)
1057 dec_nr_running(p, rq);
1058 dequeue_task(p, p->array);
1063 * task_curr - is this task currently executing on a CPU?
1064 * @p: the task in question.
1066 inline int task_curr(const struct task_struct *p)
1068 return cpu_curr(task_cpu(p)) == p;
1071 /* Used instead of source_load when we know the type == 0 */
1072 unsigned long weighted_cpuload(const int cpu)
1074 return cpu_rq(cpu)->raw_weighted_load;
1079 void set_task_cpu(struct task_struct *p, unsigned int cpu)
1081 task_thread_info(p)->cpu = cpu;
1084 struct migration_req {
1085 struct list_head list;
1087 struct task_struct *task;
1090 struct completion done;
1094 * The task's runqueue lock must be held.
1095 * Returns true if you have to wait for migration thread.
1098 migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
1100 struct rq *rq = task_rq(p);
1103 * If the task is not on a runqueue (and not running), then
1104 * it is sufficient to simply update the task's cpu field.
1106 if (!p->array && !task_running(rq, p)) {
1107 set_task_cpu(p, dest_cpu);
1111 init_completion(&req->done);
1113 req->dest_cpu = dest_cpu;
1114 list_add(&req->list, &rq->migration_queue);
1120 * wait_task_inactive - wait for a thread to unschedule.
1122 * The caller must ensure that the task *will* unschedule sometime soon,
1123 * else this function might spin for a *long* time. This function can't
1124 * be called with interrupts off, or it may introduce deadlock with
1125 * smp_call_function() if an IPI is sent by the same process we are
1126 * waiting to become inactive.
1128 void wait_task_inactive(struct task_struct *p)
1130 unsigned long flags;
1132 struct prio_array *array;
1137 * We do the initial early heuristics without holding
1138 * any task-queue locks at all. We'll only try to get
1139 * the runqueue lock when things look like they will
1145 * If the task is actively running on another CPU
1146 * still, just relax and busy-wait without holding
1149 * NOTE! Since we don't hold any locks, it's not
1150 * even sure that "rq" stays as the right runqueue!
1151 * But we don't care, since "task_running()" will
1152 * return false if the runqueue has changed and p
1153 * is actually now running somewhere else!
1155 while (task_running(rq, p))
1159 * Ok, time to look more closely! We need the rq
1160 * lock now, to be *sure*. If we're wrong, we'll
1161 * just go back and repeat.
1163 rq = task_rq_lock(p, &flags);
1164 running = task_running(rq, p);
1166 task_rq_unlock(rq, &flags);
1169 * Was it really running after all now that we
1170 * checked with the proper locks actually held?
1172 * Oops. Go back and try again..
1174 if (unlikely(running)) {
1180 * It's not enough that it's not actively running,
1181 * it must be off the runqueue _entirely_, and not
1184 * So if it wa still runnable (but just not actively
1185 * running right now), it's preempted, and we should
1186 * yield - it could be a while.
1188 if (unlikely(array)) {
1194 * Ahh, all good. It wasn't running, and it wasn't
1195 * runnable, which means that it will never become
1196 * running in the future either. We're all done!
1201 * kick_process - kick a running thread to enter/exit the kernel
1202 * @p: the to-be-kicked thread
1204 * Cause a process which is running on another CPU to enter
1205 * kernel-mode, without any delay. (to get signals handled.)
1207 * NOTE: this function doesnt have to take the runqueue lock,
1208 * because all it wants to ensure is that the remote task enters
1209 * the kernel. If the IPI races and the task has been migrated
1210 * to another CPU then no harm is done and the purpose has been
1213 void kick_process(struct task_struct *p)
1219 if ((cpu != smp_processor_id()) && task_curr(p))
1220 smp_send_reschedule(cpu);
1225 * Return a low guess at the load of a migration-source cpu weighted
1226 * according to the scheduling class and "nice" value.
1228 * We want to under-estimate the load of migration sources, to
1229 * balance conservatively.
1231 static inline unsigned long source_load(int cpu, int type)
1233 struct rq *rq = cpu_rq(cpu);
1236 return rq->raw_weighted_load;
1238 return min(rq->cpu_load[type-1], rq->raw_weighted_load);
1242 * Return a high guess at the load of a migration-target cpu weighted
1243 * according to the scheduling class and "nice" value.
1245 static inline unsigned long target_load(int cpu, int type)
1247 struct rq *rq = cpu_rq(cpu);
1250 return rq->raw_weighted_load;
1252 return max(rq->cpu_load[type-1], rq->raw_weighted_load);
1256 * Return the average load per task on the cpu's run queue
1258 static inline unsigned long cpu_avg_load_per_task(int cpu)
1260 struct rq *rq = cpu_rq(cpu);
1261 unsigned long n = rq->nr_running;
1263 return n ? rq->raw_weighted_load / n : SCHED_LOAD_SCALE;
1267 * find_idlest_group finds and returns the least busy CPU group within the
1270 static struct sched_group *
1271 find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
1273 struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
1274 unsigned long min_load = ULONG_MAX, this_load = 0;
1275 int load_idx = sd->forkexec_idx;
1276 int imbalance = 100 + (sd->imbalance_pct-100)/2;
1279 unsigned long load, avg_load;
1283 /* Skip over this group if it has no CPUs allowed */
1284 if (!cpus_intersects(group->cpumask, p->cpus_allowed))
1287 local_group = cpu_isset(this_cpu, group->cpumask);
1289 /* Tally up the load of all CPUs in the group */
1292 for_each_cpu_mask(i, group->cpumask) {
1293 /* Bias balancing toward cpus of our domain */
1295 load = source_load(i, load_idx);
1297 load = target_load(i, load_idx);
1302 /* Adjust by relative CPU power of the group */
1303 avg_load = sg_div_cpu_power(group,
1304 avg_load * SCHED_LOAD_SCALE);
1307 this_load = avg_load;
1309 } else if (avg_load < min_load) {
1310 min_load = avg_load;
1314 group = group->next;
1315 } while (group != sd->groups);
1317 if (!idlest || 100*this_load < imbalance*min_load)
1323 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1326 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
1329 unsigned long load, min_load = ULONG_MAX;
1333 /* Traverse only the allowed CPUs */
1334 cpus_and(tmp, group->cpumask, p->cpus_allowed);
1336 for_each_cpu_mask(i, tmp) {
1337 load = weighted_cpuload(i);
1339 if (load < min_load || (load == min_load && i == this_cpu)) {
1349 * sched_balance_self: balance the current task (running on cpu) in domains
1350 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1353 * Balance, ie. select the least loaded group.
1355 * Returns the target CPU number, or the same CPU if no balancing is needed.
1357 * preempt must be disabled.
1359 static int sched_balance_self(int cpu, int flag)
1361 struct task_struct *t = current;
1362 struct sched_domain *tmp, *sd = NULL;
1364 for_each_domain(cpu, tmp) {
1366 * If power savings logic is enabled for a domain, stop there.
1368 if (tmp->flags & SD_POWERSAVINGS_BALANCE)
1370 if (tmp->flags & flag)
1376 struct sched_group *group;
1377 int new_cpu, weight;
1379 if (!(sd->flags & flag)) {
1385 group = find_idlest_group(sd, t, cpu);
1391 new_cpu = find_idlest_cpu(group, t, cpu);
1392 if (new_cpu == -1 || new_cpu == cpu) {
1393 /* Now try balancing at a lower domain level of cpu */
1398 /* Now try balancing at a lower domain level of new_cpu */
1401 weight = cpus_weight(span);
1402 for_each_domain(cpu, tmp) {
1403 if (weight <= cpus_weight(tmp->span))
1405 if (tmp->flags & flag)
1408 /* while loop will break here if sd == NULL */
1414 #endif /* CONFIG_SMP */
1417 * wake_idle() will wake a task on an idle cpu if task->cpu is
1418 * not idle and an idle cpu is available. The span of cpus to
1419 * search starts with cpus closest then further out as needed,
1420 * so we always favor a closer, idle cpu.
1422 * Returns the CPU we should wake onto.
1424 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1425 static int wake_idle(int cpu, struct task_struct *p)
1428 struct sched_domain *sd;
1432 * If it is idle, then it is the best cpu to run this task.
1434 * This cpu is also the best, if it has more than one task already.
1435 * Siblings must be also busy(in most cases) as they didn't already
1436 * pickup the extra load from this cpu and hence we need not check
1437 * sibling runqueue info. This will avoid the checks and cache miss
1438 * penalities associated with that.
1440 if (idle_cpu(cpu) || cpu_rq(cpu)->nr_running > 1)
1443 for_each_domain(cpu, sd) {
1444 if (sd->flags & SD_WAKE_IDLE) {
1445 cpus_and(tmp, sd->span, p->cpus_allowed);
1446 for_each_cpu_mask(i, tmp) {
1457 static inline int wake_idle(int cpu, struct task_struct *p)
1464 * try_to_wake_up - wake up a thread
1465 * @p: the to-be-woken-up thread
1466 * @state: the mask of task states that can be woken
1467 * @sync: do a synchronous wakeup?
1469 * Put it on the run-queue if it's not already there. The "current"
1470 * thread is always on the run-queue (except when the actual
1471 * re-schedule is in progress), and as such you're allowed to do
1472 * the simpler "current->state = TASK_RUNNING" to mark yourself
1473 * runnable without the overhead of this.
1475 * returns failure only if the task is already active.
1477 static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
1479 int cpu, this_cpu, success = 0;
1480 unsigned long flags;
1484 struct sched_domain *sd, *this_sd = NULL;
1485 unsigned long load, this_load;
1489 rq = task_rq_lock(p, &flags);
1490 old_state = p->state;
1491 if (!(old_state & state))
1498 this_cpu = smp_processor_id();
1501 if (unlikely(task_running(rq, p)))
1506 schedstat_inc(rq, ttwu_cnt);
1507 if (cpu == this_cpu) {
1508 schedstat_inc(rq, ttwu_local);
1512 for_each_domain(this_cpu, sd) {
1513 if (cpu_isset(cpu, sd->span)) {
1514 schedstat_inc(sd, ttwu_wake_remote);
1520 if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
1524 * Check for affine wakeup and passive balancing possibilities.
1527 int idx = this_sd->wake_idx;
1528 unsigned int imbalance;
1530 imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
1532 load = source_load(cpu, idx);
1533 this_load = target_load(this_cpu, idx);
1535 new_cpu = this_cpu; /* Wake to this CPU if we can */
1537 if (this_sd->flags & SD_WAKE_AFFINE) {
1538 unsigned long tl = this_load;
1539 unsigned long tl_per_task;
1541 tl_per_task = cpu_avg_load_per_task(this_cpu);
1544 * If sync wakeup then subtract the (maximum possible)
1545 * effect of the currently running task from the load
1546 * of the current CPU:
1549 tl -= current->load_weight;
1552 tl + target_load(cpu, idx) <= tl_per_task) ||
1553 100*(tl + p->load_weight) <= imbalance*load) {
1555 * This domain has SD_WAKE_AFFINE and
1556 * p is cache cold in this domain, and
1557 * there is no bad imbalance.
1559 schedstat_inc(this_sd, ttwu_move_affine);
1565 * Start passive balancing when half the imbalance_pct
1568 if (this_sd->flags & SD_WAKE_BALANCE) {
1569 if (imbalance*this_load <= 100*load) {
1570 schedstat_inc(this_sd, ttwu_move_balance);
1576 new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
1578 new_cpu = wake_idle(new_cpu, p);
1579 if (new_cpu != cpu) {
1580 set_task_cpu(p, new_cpu);
1581 task_rq_unlock(rq, &flags);
1582 /* might preempt at this point */
1583 rq = task_rq_lock(p, &flags);
1584 old_state = p->state;
1585 if (!(old_state & state))
1590 this_cpu = smp_processor_id();
1595 #endif /* CONFIG_SMP */
1596 if (old_state == TASK_UNINTERRUPTIBLE)
1597 rq->nr_uninterruptible--;
1599 activate_task(p, rq, cpu == this_cpu);
1601 * Sync wakeups (i.e. those types of wakeups where the waker
1602 * has indicated that it will leave the CPU in short order)
1603 * don't trigger a preemption, if the woken up task will run on
1604 * this cpu. (in this case the 'I will reschedule' promise of
1605 * the waker guarantees that the freshly woken up task is going
1606 * to be considered on this CPU.)
1608 if (!sync || cpu != this_cpu) {
1609 if (TASK_PREEMPTS_CURR(p, rq))
1610 resched_task(rq->curr);
1615 p->state = TASK_RUNNING;
1617 task_rq_unlock(rq, &flags);
1622 int fastcall wake_up_process(struct task_struct *p)
1624 return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
1625 TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
1627 EXPORT_SYMBOL(wake_up_process);
1629 int fastcall wake_up_state(struct task_struct *p, unsigned int state)
1631 return try_to_wake_up(p, state, 0);
1634 static void task_running_tick(struct rq *rq, struct task_struct *p);
1636 * Perform scheduler related setup for a newly forked process p.
1637 * p is forked by current.
1639 void fastcall sched_fork(struct task_struct *p, int clone_flags)
1641 int cpu = get_cpu();
1644 cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
1646 set_task_cpu(p, cpu);
1649 * We mark the process as running here, but have not actually
1650 * inserted it onto the runqueue yet. This guarantees that
1651 * nobody will actually run it, and a signal or other external
1652 * event cannot wake it up and insert it on the runqueue either.
1654 p->state = TASK_RUNNING;
1657 * Make sure we do not leak PI boosting priority to the child:
1659 p->prio = current->normal_prio;
1661 INIT_LIST_HEAD(&p->run_list);
1663 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1664 if (unlikely(sched_info_on()))
1665 memset(&p->sched_info, 0, sizeof(p->sched_info));
1667 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1670 #ifdef CONFIG_PREEMPT
1671 /* Want to start with kernel preemption disabled. */
1672 task_thread_info(p)->preempt_count = 1;
1675 * Share the timeslice between parent and child, thus the
1676 * total amount of pending timeslices in the system doesn't change,
1677 * resulting in more scheduling fairness.
1679 local_irq_disable();
1680 p->time_slice = (current->time_slice + 1) >> 1;
1682 * The remainder of the first timeslice might be recovered by
1683 * the parent if the child exits early enough.
1685 p->first_time_slice = 1;
1686 current->time_slice >>= 1;
1687 p->timestamp = sched_clock();
1688 if (unlikely(!current->time_slice)) {
1690 * This case is rare, it happens when the parent has only
1691 * a single jiffy left from its timeslice. Taking the
1692 * runqueue lock is not a problem.
1694 current->time_slice = 1;
1695 task_running_tick(cpu_rq(cpu), current);
1702 * wake_up_new_task - wake up a newly created task for the first time.
1704 * This function will do some initial scheduler statistics housekeeping
1705 * that must be done for every newly created context, then puts the task
1706 * on the runqueue and wakes it.
1708 void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
1710 struct rq *rq, *this_rq;
1711 unsigned long flags;
1714 rq = task_rq_lock(p, &flags);
1715 BUG_ON(p->state != TASK_RUNNING);
1716 this_cpu = smp_processor_id();
1720 * We decrease the sleep average of forking parents
1721 * and children as well, to keep max-interactive tasks
1722 * from forking tasks that are max-interactive. The parent
1723 * (current) is done further down, under its lock.
1725 p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
1726 CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
1728 p->prio = effective_prio(p);
1730 if (likely(cpu == this_cpu)) {
1731 if (!(clone_flags & CLONE_VM)) {
1733 * The VM isn't cloned, so we're in a good position to
1734 * do child-runs-first in anticipation of an exec. This
1735 * usually avoids a lot of COW overhead.
1737 if (unlikely(!current->array))
1738 __activate_task(p, rq);
1740 p->prio = current->prio;
1741 p->normal_prio = current->normal_prio;
1742 list_add_tail(&p->run_list, ¤t->run_list);
1743 p->array = current->array;
1744 p->array->nr_active++;
1745 inc_nr_running(p, rq);
1749 /* Run child last */
1750 __activate_task(p, rq);
1752 * We skip the following code due to cpu == this_cpu
1754 * task_rq_unlock(rq, &flags);
1755 * this_rq = task_rq_lock(current, &flags);
1759 this_rq = cpu_rq(this_cpu);
1762 * Not the local CPU - must adjust timestamp. This should
1763 * get optimised away in the !CONFIG_SMP case.
1765 p->timestamp = (p->timestamp - this_rq->most_recent_timestamp)
1766 + rq->most_recent_timestamp;
1767 __activate_task(p, rq);
1768 if (TASK_PREEMPTS_CURR(p, rq))
1769 resched_task(rq->curr);
1772 * Parent and child are on different CPUs, now get the
1773 * parent runqueue to update the parent's ->sleep_avg:
1775 task_rq_unlock(rq, &flags);
1776 this_rq = task_rq_lock(current, &flags);
1778 current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
1779 PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
1780 task_rq_unlock(this_rq, &flags);
1784 * prepare_task_switch - prepare to switch tasks
1785 * @rq: the runqueue preparing to switch
1786 * @next: the task we are going to switch to.
1788 * This is called with the rq lock held and interrupts off. It must
1789 * be paired with a subsequent finish_task_switch after the context
1792 * prepare_task_switch sets up locking and calls architecture specific
1795 static inline void prepare_task_switch(struct rq *rq, struct task_struct *next)
1797 prepare_lock_switch(rq, next);
1798 prepare_arch_switch(next);
1802 * finish_task_switch - clean up after a task-switch
1803 * @rq: runqueue associated with task-switch
1804 * @prev: the thread we just switched away from.
1806 * finish_task_switch must be called after the context switch, paired
1807 * with a prepare_task_switch call before the context switch.
1808 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1809 * and do any other architecture-specific cleanup actions.
1811 * Note that we may have delayed dropping an mm in context_switch(). If
1812 * so, we finish that here outside of the runqueue lock. (Doing it
1813 * with the lock held can cause deadlocks; see schedule() for
1816 static inline void finish_task_switch(struct rq *rq, struct task_struct *prev)
1817 __releases(rq->lock)
1819 struct mm_struct *mm = rq->prev_mm;
1825 * A task struct has one reference for the use as "current".
1826 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1827 * schedule one last time. The schedule call will never return, and
1828 * the scheduled task must drop that reference.
1829 * The test for TASK_DEAD must occur while the runqueue locks are
1830 * still held, otherwise prev could be scheduled on another cpu, die
1831 * there before we look at prev->state, and then the reference would
1833 * Manfred Spraul <manfred@colorfullife.com>
1835 prev_state = prev->state;
1836 finish_arch_switch(prev);
1837 finish_lock_switch(rq, prev);
1840 if (unlikely(prev_state == TASK_DEAD)) {
1842 * Remove function-return probe instances associated with this
1843 * task and put them back on the free list.
1845 kprobe_flush_task(prev);
1846 put_task_struct(prev);
1851 * schedule_tail - first thing a freshly forked thread must call.
1852 * @prev: the thread we just switched away from.
1854 asmlinkage void schedule_tail(struct task_struct *prev)
1855 __releases(rq->lock)
1857 struct rq *rq = this_rq();
1859 finish_task_switch(rq, prev);
1860 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1861 /* In this case, finish_task_switch does not reenable preemption */
1864 if (current->set_child_tid)
1865 put_user(current->pid, current->set_child_tid);
1869 * context_switch - switch to the new MM and the new
1870 * thread's register state.
1872 static inline struct task_struct *
1873 context_switch(struct rq *rq, struct task_struct *prev,
1874 struct task_struct *next)
1876 struct mm_struct *mm = next->mm;
1877 struct mm_struct *oldmm = prev->active_mm;
1880 * For paravirt, this is coupled with an exit in switch_to to
1881 * combine the page table reload and the switch backend into
1884 arch_enter_lazy_cpu_mode();
1887 next->active_mm = oldmm;
1888 atomic_inc(&oldmm->mm_count);
1889 enter_lazy_tlb(oldmm, next);
1891 switch_mm(oldmm, mm, next);
1894 prev->active_mm = NULL;
1895 WARN_ON(rq->prev_mm);
1896 rq->prev_mm = oldmm;
1899 * Since the runqueue lock will be released by the next
1900 * task (which is an invalid locking op but in the case
1901 * of the scheduler it's an obvious special-case), so we
1902 * do an early lockdep release here:
1904 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1905 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
1908 /* Here we just switch the register state and the stack. */
1909 switch_to(prev, next, prev);
1915 * nr_running, nr_uninterruptible and nr_context_switches:
1917 * externally visible scheduler statistics: current number of runnable
1918 * threads, current number of uninterruptible-sleeping threads, total
1919 * number of context switches performed since bootup.
1921 unsigned long nr_running(void)
1923 unsigned long i, sum = 0;
1925 for_each_online_cpu(i)
1926 sum += cpu_rq(i)->nr_running;
1931 unsigned long nr_uninterruptible(void)
1933 unsigned long i, sum = 0;
1935 for_each_possible_cpu(i)
1936 sum += cpu_rq(i)->nr_uninterruptible;
1939 * Since we read the counters lockless, it might be slightly
1940 * inaccurate. Do not allow it to go below zero though:
1942 if (unlikely((long)sum < 0))
1948 unsigned long long nr_context_switches(void)
1951 unsigned long long sum = 0;
1953 for_each_possible_cpu(i)
1954 sum += cpu_rq(i)->nr_switches;
1959 unsigned long nr_iowait(void)
1961 unsigned long i, sum = 0;
1963 for_each_possible_cpu(i)
1964 sum += atomic_read(&cpu_rq(i)->nr_iowait);
1969 unsigned long nr_active(void)
1971 unsigned long i, running = 0, uninterruptible = 0;
1973 for_each_online_cpu(i) {
1974 running += cpu_rq(i)->nr_running;
1975 uninterruptible += cpu_rq(i)->nr_uninterruptible;
1978 if (unlikely((long)uninterruptible < 0))
1979 uninterruptible = 0;
1981 return running + uninterruptible;
1987 * Is this task likely cache-hot:
1990 task_hot(struct task_struct *p, unsigned long long now, struct sched_domain *sd)
1992 return (long long)(now - p->last_ran) < (long long)sd->cache_hot_time;
1996 * double_rq_lock - safely lock two runqueues
1998 * Note this does not disable interrupts like task_rq_lock,
1999 * you need to do so manually before calling.
2001 static void double_rq_lock(struct rq *rq1, struct rq *rq2)
2002 __acquires(rq1->lock)
2003 __acquires(rq2->lock)
2005 BUG_ON(!irqs_disabled());
2007 spin_lock(&rq1->lock);
2008 __acquire(rq2->lock); /* Fake it out ;) */
2011 spin_lock(&rq1->lock);
2012 spin_lock(&rq2->lock);
2014 spin_lock(&rq2->lock);
2015 spin_lock(&rq1->lock);
2021 * double_rq_unlock - safely unlock two runqueues
2023 * Note this does not restore interrupts like task_rq_unlock,
2024 * you need to do so manually after calling.
2026 static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
2027 __releases(rq1->lock)
2028 __releases(rq2->lock)
2030 spin_unlock(&rq1->lock);
2032 spin_unlock(&rq2->lock);
2034 __release(rq2->lock);
2038 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2040 static void double_lock_balance(struct rq *this_rq, struct rq *busiest)
2041 __releases(this_rq->lock)
2042 __acquires(busiest->lock)
2043 __acquires(this_rq->lock)
2045 if (unlikely(!irqs_disabled())) {
2046 /* printk() doesn't work good under rq->lock */
2047 spin_unlock(&this_rq->lock);
2050 if (unlikely(!spin_trylock(&busiest->lock))) {
2051 if (busiest < this_rq) {
2052 spin_unlock(&this_rq->lock);
2053 spin_lock(&busiest->lock);
2054 spin_lock(&this_rq->lock);
2056 spin_lock(&busiest->lock);
2061 * If dest_cpu is allowed for this process, migrate the task to it.
2062 * This is accomplished by forcing the cpu_allowed mask to only
2063 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2064 * the cpu_allowed mask is restored.
2066 static void sched_migrate_task(struct task_struct *p, int dest_cpu)
2068 struct migration_req req;
2069 unsigned long flags;
2072 rq = task_rq_lock(p, &flags);
2073 if (!cpu_isset(dest_cpu, p->cpus_allowed)
2074 || unlikely(cpu_is_offline(dest_cpu)))
2077 /* force the process onto the specified CPU */
2078 if (migrate_task(p, dest_cpu, &req)) {
2079 /* Need to wait for migration thread (might exit: take ref). */
2080 struct task_struct *mt = rq->migration_thread;
2082 get_task_struct(mt);
2083 task_rq_unlock(rq, &flags);
2084 wake_up_process(mt);
2085 put_task_struct(mt);
2086 wait_for_completion(&req.done);
2091 task_rq_unlock(rq, &flags);
2095 * sched_exec - execve() is a valuable balancing opportunity, because at
2096 * this point the task has the smallest effective memory and cache footprint.
2098 void sched_exec(void)
2100 int new_cpu, this_cpu = get_cpu();
2101 new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
2103 if (new_cpu != this_cpu)
2104 sched_migrate_task(current, new_cpu);
2108 * pull_task - move a task from a remote runqueue to the local runqueue.
2109 * Both runqueues must be locked.
2111 static void pull_task(struct rq *src_rq, struct prio_array *src_array,
2112 struct task_struct *p, struct rq *this_rq,
2113 struct prio_array *this_array, int this_cpu)
2115 dequeue_task(p, src_array);
2116 dec_nr_running(p, src_rq);
2117 set_task_cpu(p, this_cpu);
2118 inc_nr_running(p, this_rq);
2119 enqueue_task(p, this_array);
2120 p->timestamp = (p->timestamp - src_rq->most_recent_timestamp)
2121 + this_rq->most_recent_timestamp;
2123 * Note that idle threads have a prio of MAX_PRIO, for this test
2124 * to be always true for them.
2126 if (TASK_PREEMPTS_CURR(p, this_rq))
2127 resched_task(this_rq->curr);
2131 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2134 int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
2135 struct sched_domain *sd, enum cpu_idle_type idle,
2139 * We do not migrate tasks that are:
2140 * 1) running (obviously), or
2141 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2142 * 3) are cache-hot on their current CPU.
2144 if (!cpu_isset(this_cpu, p->cpus_allowed))
2148 if (task_running(rq, p))
2152 * Aggressive migration if:
2153 * 1) task is cache cold, or
2154 * 2) too many balance attempts have failed.
2157 if (sd->nr_balance_failed > sd->cache_nice_tries) {
2158 #ifdef CONFIG_SCHEDSTATS
2159 if (task_hot(p, rq->most_recent_timestamp, sd))
2160 schedstat_inc(sd, lb_hot_gained[idle]);
2165 if (task_hot(p, rq->most_recent_timestamp, sd))
2170 #define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio)
2173 * move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
2174 * load from busiest to this_rq, as part of a balancing operation within
2175 * "domain". Returns the number of tasks moved.
2177 * Called with both runqueues locked.
2179 static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2180 unsigned long max_nr_move, unsigned long max_load_move,
2181 struct sched_domain *sd, enum cpu_idle_type idle,
2184 int idx, pulled = 0, pinned = 0, this_best_prio, best_prio,
2185 best_prio_seen, skip_for_load;
2186 struct prio_array *array, *dst_array;
2187 struct list_head *head, *curr;
2188 struct task_struct *tmp;
2191 if (max_nr_move == 0 || max_load_move == 0)
2194 rem_load_move = max_load_move;
2196 this_best_prio = rq_best_prio(this_rq);
2197 best_prio = rq_best_prio(busiest);
2199 * Enable handling of the case where there is more than one task
2200 * with the best priority. If the current running task is one
2201 * of those with prio==best_prio we know it won't be moved
2202 * and therefore it's safe to override the skip (based on load) of
2203 * any task we find with that prio.
2205 best_prio_seen = best_prio == busiest->curr->prio;
2208 * We first consider expired tasks. Those will likely not be
2209 * executed in the near future, and they are most likely to
2210 * be cache-cold, thus switching CPUs has the least effect
2213 if (busiest->expired->nr_active) {
2214 array = busiest->expired;
2215 dst_array = this_rq->expired;
2217 array = busiest->active;
2218 dst_array = this_rq->active;
2222 /* Start searching at priority 0: */
2226 idx = sched_find_first_bit(array->bitmap);
2228 idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
2229 if (idx >= MAX_PRIO) {
2230 if (array == busiest->expired && busiest->active->nr_active) {
2231 array = busiest->active;
2232 dst_array = this_rq->active;
2238 head = array->queue + idx;
2241 tmp = list_entry(curr, struct task_struct, run_list);
2246 * To help distribute high priority tasks accross CPUs we don't
2247 * skip a task if it will be the highest priority task (i.e. smallest
2248 * prio value) on its new queue regardless of its load weight
2250 skip_for_load = tmp->load_weight > rem_load_move;
2251 if (skip_for_load && idx < this_best_prio)
2252 skip_for_load = !best_prio_seen && idx == best_prio;
2253 if (skip_for_load ||
2254 !can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) {
2256 best_prio_seen |= idx == best_prio;
2263 pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
2265 rem_load_move -= tmp->load_weight;
2268 * We only want to steal up to the prescribed number of tasks
2269 * and the prescribed amount of weighted load.
2271 if (pulled < max_nr_move && rem_load_move > 0) {
2272 if (idx < this_best_prio)
2273 this_best_prio = idx;
2281 * Right now, this is the only place pull_task() is called,
2282 * so we can safely collect pull_task() stats here rather than
2283 * inside pull_task().
2285 schedstat_add(sd, lb_gained[idle], pulled);
2288 *all_pinned = pinned;
2293 * find_busiest_group finds and returns the busiest CPU group within the
2294 * domain. It calculates and returns the amount of weighted load which
2295 * should be moved to restore balance via the imbalance parameter.
2297 static struct sched_group *
2298 find_busiest_group(struct sched_domain *sd, int this_cpu,
2299 unsigned long *imbalance, enum cpu_idle_type idle, int *sd_idle,
2300 cpumask_t *cpus, int *balance)
2302 struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
2303 unsigned long max_load, avg_load, total_load, this_load, total_pwr;
2304 unsigned long max_pull;
2305 unsigned long busiest_load_per_task, busiest_nr_running;
2306 unsigned long this_load_per_task, this_nr_running;
2308 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2309 int power_savings_balance = 1;
2310 unsigned long leader_nr_running = 0, min_load_per_task = 0;
2311 unsigned long min_nr_running = ULONG_MAX;
2312 struct sched_group *group_min = NULL, *group_leader = NULL;
2315 max_load = this_load = total_load = total_pwr = 0;
2316 busiest_load_per_task = busiest_nr_running = 0;
2317 this_load_per_task = this_nr_running = 0;
2318 if (idle == CPU_NOT_IDLE)
2319 load_idx = sd->busy_idx;
2320 else if (idle == CPU_NEWLY_IDLE)
2321 load_idx = sd->newidle_idx;
2323 load_idx = sd->idle_idx;
2326 unsigned long load, group_capacity;
2329 unsigned int balance_cpu = -1, first_idle_cpu = 0;
2330 unsigned long sum_nr_running, sum_weighted_load;
2332 local_group = cpu_isset(this_cpu, group->cpumask);
2335 balance_cpu = first_cpu(group->cpumask);
2337 /* Tally up the load of all CPUs in the group */
2338 sum_weighted_load = sum_nr_running = avg_load = 0;
2340 for_each_cpu_mask(i, group->cpumask) {
2343 if (!cpu_isset(i, *cpus))
2348 if (*sd_idle && !idle_cpu(i))
2351 /* Bias balancing toward cpus of our domain */
2353 if (idle_cpu(i) && !first_idle_cpu) {
2358 load = target_load(i, load_idx);
2360 load = source_load(i, load_idx);
2363 sum_nr_running += rq->nr_running;
2364 sum_weighted_load += rq->raw_weighted_load;
2368 * First idle cpu or the first cpu(busiest) in this sched group
2369 * is eligible for doing load balancing at this and above
2372 if (local_group && balance_cpu != this_cpu && balance) {
2377 total_load += avg_load;
2378 total_pwr += group->__cpu_power;
2380 /* Adjust by relative CPU power of the group */
2381 avg_load = sg_div_cpu_power(group,
2382 avg_load * SCHED_LOAD_SCALE);
2384 group_capacity = group->__cpu_power / SCHED_LOAD_SCALE;
2387 this_load = avg_load;
2389 this_nr_running = sum_nr_running;
2390 this_load_per_task = sum_weighted_load;
2391 } else if (avg_load > max_load &&
2392 sum_nr_running > group_capacity) {
2393 max_load = avg_load;
2395 busiest_nr_running = sum_nr_running;
2396 busiest_load_per_task = sum_weighted_load;
2399 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2401 * Busy processors will not participate in power savings
2404 if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
2408 * If the local group is idle or completely loaded
2409 * no need to do power savings balance at this domain
2411 if (local_group && (this_nr_running >= group_capacity ||
2413 power_savings_balance = 0;
2416 * If a group is already running at full capacity or idle,
2417 * don't include that group in power savings calculations
2419 if (!power_savings_balance || sum_nr_running >= group_capacity
2424 * Calculate the group which has the least non-idle load.
2425 * This is the group from where we need to pick up the load
2428 if ((sum_nr_running < min_nr_running) ||
2429 (sum_nr_running == min_nr_running &&
2430 first_cpu(group->cpumask) <
2431 first_cpu(group_min->cpumask))) {
2433 min_nr_running = sum_nr_running;
2434 min_load_per_task = sum_weighted_load /
2439 * Calculate the group which is almost near its
2440 * capacity but still has some space to pick up some load
2441 * from other group and save more power
2443 if (sum_nr_running <= group_capacity - 1) {
2444 if (sum_nr_running > leader_nr_running ||
2445 (sum_nr_running == leader_nr_running &&
2446 first_cpu(group->cpumask) >
2447 first_cpu(group_leader->cpumask))) {
2448 group_leader = group;
2449 leader_nr_running = sum_nr_running;
2454 group = group->next;
2455 } while (group != sd->groups);
2457 if (!busiest || this_load >= max_load || busiest_nr_running == 0)
2460 avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
2462 if (this_load >= avg_load ||
2463 100*max_load <= sd->imbalance_pct*this_load)
2466 busiest_load_per_task /= busiest_nr_running;
2468 * We're trying to get all the cpus to the average_load, so we don't
2469 * want to push ourselves above the average load, nor do we wish to
2470 * reduce the max loaded cpu below the average load, as either of these
2471 * actions would just result in more rebalancing later, and ping-pong
2472 * tasks around. Thus we look for the minimum possible imbalance.
2473 * Negative imbalances (*we* are more loaded than anyone else) will
2474 * be counted as no imbalance for these purposes -- we can't fix that
2475 * by pulling tasks to us. Be careful of negative numbers as they'll
2476 * appear as very large values with unsigned longs.
2478 if (max_load <= busiest_load_per_task)
2482 * In the presence of smp nice balancing, certain scenarios can have
2483 * max load less than avg load(as we skip the groups at or below
2484 * its cpu_power, while calculating max_load..)
2486 if (max_load < avg_load) {
2488 goto small_imbalance;
2491 /* Don't want to pull so many tasks that a group would go idle */
2492 max_pull = min(max_load - avg_load, max_load - busiest_load_per_task);
2494 /* How much load to actually move to equalise the imbalance */
2495 *imbalance = min(max_pull * busiest->__cpu_power,
2496 (avg_load - this_load) * this->__cpu_power)
2500 * if *imbalance is less than the average load per runnable task
2501 * there is no gaurantee that any tasks will be moved so we'll have
2502 * a think about bumping its value to force at least one task to be
2505 if (*imbalance < busiest_load_per_task) {
2506 unsigned long tmp, pwr_now, pwr_move;
2510 pwr_move = pwr_now = 0;
2512 if (this_nr_running) {
2513 this_load_per_task /= this_nr_running;
2514 if (busiest_load_per_task > this_load_per_task)
2517 this_load_per_task = SCHED_LOAD_SCALE;
2519 if (max_load - this_load >= busiest_load_per_task * imbn) {
2520 *imbalance = busiest_load_per_task;
2525 * OK, we don't have enough imbalance to justify moving tasks,
2526 * however we may be able to increase total CPU power used by
2530 pwr_now += busiest->__cpu_power *
2531 min(busiest_load_per_task, max_load);
2532 pwr_now += this->__cpu_power *
2533 min(this_load_per_task, this_load);
2534 pwr_now /= SCHED_LOAD_SCALE;
2536 /* Amount of load we'd subtract */
2537 tmp = sg_div_cpu_power(busiest,
2538 busiest_load_per_task * SCHED_LOAD_SCALE);
2540 pwr_move += busiest->__cpu_power *
2541 min(busiest_load_per_task, max_load - tmp);
2543 /* Amount of load we'd add */
2544 if (max_load * busiest->__cpu_power <
2545 busiest_load_per_task * SCHED_LOAD_SCALE)
2546 tmp = sg_div_cpu_power(this,
2547 max_load * busiest->__cpu_power);
2549 tmp = sg_div_cpu_power(this,
2550 busiest_load_per_task * SCHED_LOAD_SCALE);
2551 pwr_move += this->__cpu_power *
2552 min(this_load_per_task, this_load + tmp);
2553 pwr_move /= SCHED_LOAD_SCALE;
2555 /* Move if we gain throughput */
2556 if (pwr_move <= pwr_now)
2559 *imbalance = busiest_load_per_task;
2565 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2566 if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
2569 if (this == group_leader && group_leader != group_min) {
2570 *imbalance = min_load_per_task;
2580 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2583 find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
2584 unsigned long imbalance, cpumask_t *cpus)
2586 struct rq *busiest = NULL, *rq;
2587 unsigned long max_load = 0;
2590 for_each_cpu_mask(i, group->cpumask) {
2592 if (!cpu_isset(i, *cpus))
2597 if (rq->nr_running == 1 && rq->raw_weighted_load > imbalance)
2600 if (rq->raw_weighted_load > max_load) {
2601 max_load = rq->raw_weighted_load;
2610 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2611 * so long as it is large enough.
2613 #define MAX_PINNED_INTERVAL 512
2615 static inline unsigned long minus_1_or_zero(unsigned long n)
2617 return n > 0 ? n - 1 : 0;
2621 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2622 * tasks if there is an imbalance.
2624 static int load_balance(int this_cpu, struct rq *this_rq,
2625 struct sched_domain *sd, enum cpu_idle_type idle,
2628 int nr_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
2629 struct sched_group *group;
2630 unsigned long imbalance;
2632 cpumask_t cpus = CPU_MASK_ALL;
2633 unsigned long flags;
2636 * When power savings policy is enabled for the parent domain, idle
2637 * sibling can pick up load irrespective of busy siblings. In this case,
2638 * let the state of idle sibling percolate up as IDLE, instead of
2639 * portraying it as CPU_NOT_IDLE.
2641 if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
2642 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2645 schedstat_inc(sd, lb_cnt[idle]);
2648 group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
2655 schedstat_inc(sd, lb_nobusyg[idle]);
2659 busiest = find_busiest_queue(group, idle, imbalance, &cpus);
2661 schedstat_inc(sd, lb_nobusyq[idle]);
2665 BUG_ON(busiest == this_rq);
2667 schedstat_add(sd, lb_imbalance[idle], imbalance);
2670 if (busiest->nr_running > 1) {
2672 * Attempt to move tasks. If find_busiest_group has found
2673 * an imbalance but busiest->nr_running <= 1, the group is
2674 * still unbalanced. nr_moved simply stays zero, so it is
2675 * correctly treated as an imbalance.
2677 local_irq_save(flags);
2678 double_rq_lock(this_rq, busiest);
2679 nr_moved = move_tasks(this_rq, this_cpu, busiest,
2680 minus_1_or_zero(busiest->nr_running),
2681 imbalance, sd, idle, &all_pinned);
2682 double_rq_unlock(this_rq, busiest);
2683 local_irq_restore(flags);
2686 * some other cpu did the load balance for us.
2688 if (nr_moved && this_cpu != smp_processor_id())
2689 resched_cpu(this_cpu);
2691 /* All tasks on this runqueue were pinned by CPU affinity */
2692 if (unlikely(all_pinned)) {
2693 cpu_clear(cpu_of(busiest), cpus);
2694 if (!cpus_empty(cpus))
2701 schedstat_inc(sd, lb_failed[idle]);
2702 sd->nr_balance_failed++;
2704 if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
2706 spin_lock_irqsave(&busiest->lock, flags);
2708 /* don't kick the migration_thread, if the curr
2709 * task on busiest cpu can't be moved to this_cpu
2711 if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) {
2712 spin_unlock_irqrestore(&busiest->lock, flags);
2714 goto out_one_pinned;
2717 if (!busiest->active_balance) {
2718 busiest->active_balance = 1;
2719 busiest->push_cpu = this_cpu;
2722 spin_unlock_irqrestore(&busiest->lock, flags);
2724 wake_up_process(busiest->migration_thread);
2727 * We've kicked active balancing, reset the failure
2730 sd->nr_balance_failed = sd->cache_nice_tries+1;
2733 sd->nr_balance_failed = 0;
2735 if (likely(!active_balance)) {
2736 /* We were unbalanced, so reset the balancing interval */
2737 sd->balance_interval = sd->min_interval;
2740 * If we've begun active balancing, start to back off. This
2741 * case may not be covered by the all_pinned logic if there
2742 * is only 1 task on the busy runqueue (because we don't call
2745 if (sd->balance_interval < sd->max_interval)
2746 sd->balance_interval *= 2;
2749 if (!nr_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2750 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2755 schedstat_inc(sd, lb_balanced[idle]);
2757 sd->nr_balance_failed = 0;
2760 /* tune up the balancing interval */
2761 if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
2762 (sd->balance_interval < sd->max_interval))
2763 sd->balance_interval *= 2;
2765 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2766 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2772 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2773 * tasks if there is an imbalance.
2775 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
2776 * this_rq is locked.
2779 load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
2781 struct sched_group *group;
2782 struct rq *busiest = NULL;
2783 unsigned long imbalance;
2786 cpumask_t cpus = CPU_MASK_ALL;
2789 * When power savings policy is enabled for the parent domain, idle
2790 * sibling can pick up load irrespective of busy siblings. In this case,
2791 * let the state of idle sibling percolate up as IDLE, instead of
2792 * portraying it as CPU_NOT_IDLE.
2794 if (sd->flags & SD_SHARE_CPUPOWER &&
2795 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2798 schedstat_inc(sd, lb_cnt[CPU_NEWLY_IDLE]);
2800 group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE,
2801 &sd_idle, &cpus, NULL);
2803 schedstat_inc(sd, lb_nobusyg[CPU_NEWLY_IDLE]);
2807 busiest = find_busiest_queue(group, CPU_NEWLY_IDLE, imbalance,
2810 schedstat_inc(sd, lb_nobusyq[CPU_NEWLY_IDLE]);
2814 BUG_ON(busiest == this_rq);
2816 schedstat_add(sd, lb_imbalance[CPU_NEWLY_IDLE], imbalance);
2819 if (busiest->nr_running > 1) {
2820 /* Attempt to move tasks */
2821 double_lock_balance(this_rq, busiest);
2822 nr_moved = move_tasks(this_rq, this_cpu, busiest,
2823 minus_1_or_zero(busiest->nr_running),
2824 imbalance, sd, CPU_NEWLY_IDLE, NULL);
2825 spin_unlock(&busiest->lock);
2828 cpu_clear(cpu_of(busiest), cpus);
2829 if (!cpus_empty(cpus))
2835 schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
2836 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2837 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2840 sd->nr_balance_failed = 0;
2845 schedstat_inc(sd, lb_balanced[CPU_NEWLY_IDLE]);
2846 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2847 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
2849 sd->nr_balance_failed = 0;
2855 * idle_balance is called by schedule() if this_cpu is about to become
2856 * idle. Attempts to pull tasks from other CPUs.
2858 static void idle_balance(int this_cpu, struct rq *this_rq)
2860 struct sched_domain *sd;
2861 int pulled_task = 0;
2862 unsigned long next_balance = jiffies + 60 * HZ;
2864 for_each_domain(this_cpu, sd) {
2865 unsigned long interval;
2867 if (!(sd->flags & SD_LOAD_BALANCE))
2870 if (sd->flags & SD_BALANCE_NEWIDLE)
2871 /* If we've pulled tasks over stop searching: */
2872 pulled_task = load_balance_newidle(this_cpu,
2875 interval = msecs_to_jiffies(sd->balance_interval);
2876 if (time_after(next_balance, sd->last_balance + interval))
2877 next_balance = sd->last_balance + interval;
2883 * We are going idle. next_balance may be set based on
2884 * a busy processor. So reset next_balance.
2886 this_rq->next_balance = next_balance;
2890 * active_load_balance is run by migration threads. It pushes running tasks
2891 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2892 * running on each physical CPU where possible, and avoids physical /
2893 * logical imbalances.
2895 * Called with busiest_rq locked.
2897 static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
2899 int target_cpu = busiest_rq->push_cpu;
2900 struct sched_domain *sd;
2901 struct rq *target_rq;
2903 /* Is there any task to move? */
2904 if (busiest_rq->nr_running <= 1)
2907 target_rq = cpu_rq(target_cpu);
2910 * This condition is "impossible", if it occurs
2911 * we need to fix it. Originally reported by
2912 * Bjorn Helgaas on a 128-cpu setup.
2914 BUG_ON(busiest_rq == target_rq);
2916 /* move a task from busiest_rq to target_rq */
2917 double_lock_balance(busiest_rq, target_rq);
2919 /* Search for an sd spanning us and the target CPU. */
2920 for_each_domain(target_cpu, sd) {
2921 if ((sd->flags & SD_LOAD_BALANCE) &&
2922 cpu_isset(busiest_cpu, sd->span))
2927 schedstat_inc(sd, alb_cnt);
2929 if (move_tasks(target_rq, target_cpu, busiest_rq, 1,
2930 RTPRIO_TO_LOAD_WEIGHT(100), sd, CPU_IDLE,
2932 schedstat_inc(sd, alb_pushed);
2934 schedstat_inc(sd, alb_failed);
2936 spin_unlock(&target_rq->lock);
2939 static void update_load(struct rq *this_rq)
2941 unsigned long this_load;
2942 unsigned int i, scale;
2944 this_load = this_rq->raw_weighted_load;
2946 /* Update our load: */
2947 for (i = 0, scale = 1; i < 3; i++, scale += scale) {
2948 unsigned long old_load, new_load;
2950 /* scale is effectively 1 << i now, and >> i divides by scale */
2952 old_load = this_rq->cpu_load[i];
2953 new_load = this_load;
2955 * Round up the averaging division if load is increasing. This
2956 * prevents us from getting stuck on 9 if the load is 10, for
2959 if (new_load > old_load)
2960 new_load += scale-1;
2961 this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
2967 atomic_t load_balancer;
2969 } nohz ____cacheline_aligned = {
2970 .load_balancer = ATOMIC_INIT(-1),
2971 .cpu_mask = CPU_MASK_NONE,
2975 * This routine will try to nominate the ilb (idle load balancing)
2976 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
2977 * load balancing on behalf of all those cpus. If all the cpus in the system
2978 * go into this tickless mode, then there will be no ilb owner (as there is
2979 * no need for one) and all the cpus will sleep till the next wakeup event
2982 * For the ilb owner, tick is not stopped. And this tick will be used
2983 * for idle load balancing. ilb owner will still be part of
2986 * While stopping the tick, this cpu will become the ilb owner if there
2987 * is no other owner. And will be the owner till that cpu becomes busy
2988 * or if all cpus in the system stop their ticks at which point
2989 * there is no need for ilb owner.
2991 * When the ilb owner becomes busy, it nominates another owner, during the
2992 * next busy scheduler_tick()
2994 int select_nohz_load_balancer(int stop_tick)
2996 int cpu = smp_processor_id();
2999 cpu_set(cpu, nohz.cpu_mask);
3000 cpu_rq(cpu)->in_nohz_recently = 1;
3003 * If we are going offline and still the leader, give up!
3005 if (cpu_is_offline(cpu) &&
3006 atomic_read(&nohz.load_balancer) == cpu) {
3007 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
3012 /* time for ilb owner also to sleep */
3013 if (cpus_weight(nohz.cpu_mask) == num_online_cpus()) {
3014 if (atomic_read(&nohz.load_balancer) == cpu)
3015 atomic_set(&nohz.load_balancer, -1);
3019 if (atomic_read(&nohz.load_balancer) == -1) {
3020 /* make me the ilb owner */
3021 if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
3023 } else if (atomic_read(&nohz.load_balancer) == cpu)
3026 if (!cpu_isset(cpu, nohz.cpu_mask))
3029 cpu_clear(cpu, nohz.cpu_mask);
3031 if (atomic_read(&nohz.load_balancer) == cpu)
3032 if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
3039 static DEFINE_SPINLOCK(balancing);
3042 * It checks each scheduling domain to see if it is due to be balanced,
3043 * and initiates a balancing operation if so.
3045 * Balancing parameters are set up in arch_init_sched_domains.
3047 static inline void rebalance_domains(int cpu, enum cpu_idle_type idle)
3050 struct rq *rq = cpu_rq(cpu);
3051 unsigned long interval;
3052 struct sched_domain *sd;
3053 /* Earliest time when we have to do rebalance again */
3054 unsigned long next_balance = jiffies + 60*HZ;
3056 for_each_domain(cpu, sd) {
3057 if (!(sd->flags & SD_LOAD_BALANCE))
3060 interval = sd->balance_interval;
3061 if (idle != CPU_IDLE)
3062 interval *= sd->busy_factor;
3064 /* scale ms to jiffies */
3065 interval = msecs_to_jiffies(interval);
3066 if (unlikely(!interval))
3069 if (sd->flags & SD_SERIALIZE) {
3070 if (!spin_trylock(&balancing))
3074 if (time_after_eq(jiffies, sd->last_balance + interval)) {
3075 if (load_balance(cpu, rq, sd, idle, &balance)) {
3077 * We've pulled tasks over so either we're no
3078 * longer idle, or one of our SMT siblings is
3081 idle = CPU_NOT_IDLE;
3083 sd->last_balance = jiffies;
3085 if (sd->flags & SD_SERIALIZE)
3086 spin_unlock(&balancing);
3088 if (time_after(next_balance, sd->last_balance + interval))
3089 next_balance = sd->last_balance + interval;
3092 * Stop the load balance at this level. There is another
3093 * CPU in our sched group which is doing load balancing more
3099 rq->next_balance = next_balance;
3103 * run_rebalance_domains is triggered when needed from the scheduler tick.
3104 * In CONFIG_NO_HZ case, the idle load balance owner will do the
3105 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3107 static void run_rebalance_domains(struct softirq_action *h)
3109 int local_cpu = smp_processor_id();
3110 struct rq *local_rq = cpu_rq(local_cpu);
3111 enum cpu_idle_type idle = local_rq->idle_at_tick ? CPU_IDLE : CPU_NOT_IDLE;
3113 rebalance_domains(local_cpu, idle);
3117 * If this cpu is the owner for idle load balancing, then do the
3118 * balancing on behalf of the other idle cpus whose ticks are
3121 if (local_rq->idle_at_tick &&
3122 atomic_read(&nohz.load_balancer) == local_cpu) {
3123 cpumask_t cpus = nohz.cpu_mask;
3127 cpu_clear(local_cpu, cpus);
3128 for_each_cpu_mask(balance_cpu, cpus) {
3130 * If this cpu gets work to do, stop the load balancing
3131 * work being done for other cpus. Next load
3132 * balancing owner will pick it up.
3137 rebalance_domains(balance_cpu, CPU_IDLE);
3139 rq = cpu_rq(balance_cpu);
3140 if (time_after(local_rq->next_balance, rq->next_balance))
3141 local_rq->next_balance = rq->next_balance;
3148 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3150 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3151 * idle load balancing owner or decide to stop the periodic load balancing,
3152 * if the whole system is idle.
3154 static inline void trigger_load_balance(int cpu)
3156 struct rq *rq = cpu_rq(cpu);
3159 * If we were in the nohz mode recently and busy at the current
3160 * scheduler tick, then check if we need to nominate new idle
3163 if (rq->in_nohz_recently && !rq->idle_at_tick) {
3164 rq->in_nohz_recently = 0;
3166 if (atomic_read(&nohz.load_balancer) == cpu) {
3167 cpu_clear(cpu, nohz.cpu_mask);
3168 atomic_set(&nohz.load_balancer, -1);
3171 if (atomic_read(&nohz.load_balancer) == -1) {
3173 * simple selection for now: Nominate the
3174 * first cpu in the nohz list to be the next
3177 * TBD: Traverse the sched domains and nominate
3178 * the nearest cpu in the nohz.cpu_mask.
3180 int ilb = first_cpu(nohz.cpu_mask);
3188 * If this cpu is idle and doing idle load balancing for all the
3189 * cpus with ticks stopped, is it time for that to stop?
3191 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
3192 cpus_weight(nohz.cpu_mask) == num_online_cpus()) {
3198 * If this cpu is idle and the idle load balancing is done by
3199 * someone else, then no need raise the SCHED_SOFTIRQ
3201 if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
3202 cpu_isset(cpu, nohz.cpu_mask))
3205 if (time_after_eq(jiffies, rq->next_balance))
3206 raise_softirq(SCHED_SOFTIRQ);
3210 * on UP we do not need to balance between CPUs:
3212 static inline void idle_balance(int cpu, struct rq *rq)
3217 DEFINE_PER_CPU(struct kernel_stat, kstat);
3219 EXPORT_PER_CPU_SYMBOL(kstat);
3222 * Return p->sum_exec_runtime plus any more ns on the sched_clock
3223 * that have not yet been banked in case the task is currently running.
3225 unsigned long long task_sched_runtime(struct task_struct *p)
3227 unsigned long flags;
3231 rq = task_rq_lock(p, &flags);
3232 ns = p->se.sum_exec_runtime;
3233 if (rq->curr == p) {
3234 delta_exec = rq_clock(rq) - p->se.exec_start;
3235 if ((s64)delta_exec > 0)
3238 task_rq_unlock(rq, &flags);
3244 * We place interactive tasks back into the active array, if possible.
3246 * To guarantee that this does not starve expired tasks we ignore the
3247 * interactivity of a task if the first expired task had to wait more
3248 * than a 'reasonable' amount of time. This deadline timeout is
3249 * load-dependent, as the frequency of array switched decreases with
3250 * increasing number of running tasks. We also ignore the interactivity
3251 * if a better static_prio task has expired:
3253 static inline int expired_starving(struct rq *rq)
3255 if (rq->curr->static_prio > rq->best_expired_prio)
3257 if (!STARVATION_LIMIT || !rq->expired_timestamp)
3259 if (jiffies - rq->expired_timestamp > STARVATION_LIMIT * rq->nr_running)
3265 * Account user cpu time to a process.
3266 * @p: the process that the cpu time gets accounted to
3267 * @hardirq_offset: the offset to subtract from hardirq_count()
3268 * @cputime: the cpu time spent in user space since the last update
3270 void account_user_time(struct task_struct *p, cputime_t cputime)
3272 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3275 p->utime = cputime_add(p->utime, cputime);
3277 /* Add user time to cpustat. */
3278 tmp = cputime_to_cputime64(cputime);
3279 if (TASK_NICE(p) > 0)
3280 cpustat->nice = cputime64_add(cpustat->nice, tmp);
3282 cpustat->user = cputime64_add(cpustat->user, tmp);
3286 * Account system cpu time to a process.
3287 * @p: the process that the cpu time gets accounted to
3288 * @hardirq_offset: the offset to subtract from hardirq_count()
3289 * @cputime: the cpu time spent in kernel space since the last update
3291 void account_system_time(struct task_struct *p, int hardirq_offset,
3294 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3295 struct rq *rq = this_rq();
3298 p->stime = cputime_add(p->stime, cputime);
3300 /* Add system time to cpustat. */
3301 tmp = cputime_to_cputime64(cputime);
3302 if (hardirq_count() - hardirq_offset)
3303 cpustat->irq = cputime64_add(cpustat->irq, tmp);
3304 else if (softirq_count())
3305 cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
3306 else if (p != rq->idle)
3307 cpustat->system = cputime64_add(cpustat->system, tmp);
3308 else if (atomic_read(&rq->nr_iowait) > 0)
3309 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
3311 cpustat->idle = cputime64_add(cpustat->idle, tmp);
3312 /* Account for system time used */
3313 acct_update_integrals(p);
3317 * Account for involuntary wait time.
3318 * @p: the process from which the cpu time has been stolen
3319 * @steal: the cpu time spent in involuntary wait
3321 void account_steal_time(struct task_struct *p, cputime_t steal)
3323 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3324 cputime64_t tmp = cputime_to_cputime64(steal);
3325 struct rq *rq = this_rq();
3327 if (p == rq->idle) {
3328 p->stime = cputime_add(p->stime, steal);
3329 if (atomic_read(&rq->nr_iowait) > 0)
3330 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
3332 cpustat->idle = cputime64_add(cpustat->idle, tmp);
3334 cpustat->steal = cputime64_add(cpustat->steal, tmp);
3337 static void task_running_tick(struct rq *rq, struct task_struct *p)
3339 if (p->array != rq->active) {
3340 /* Task has expired but was not scheduled yet */
3341 set_tsk_need_resched(p);
3344 spin_lock(&rq->lock);
3346 * The task was running during this tick - update the
3347 * time slice counter. Note: we do not update a thread's
3348 * priority until it either goes to sleep or uses up its
3349 * timeslice. This makes it possible for interactive tasks
3350 * to use up their timeslices at their highest priority levels.
3354 * RR tasks need a special form of timeslice management.
3355 * FIFO tasks have no timeslices.
3357 if ((p->policy == SCHED_RR) && !--p->time_slice) {
3358 p->time_slice = task_timeslice(p);
3359 p->first_time_slice = 0;
3360 set_tsk_need_resched(p);
3362 /* put it at the end of the queue: */
3363 requeue_task(p, rq->active);
3367 if (!--p->time_slice) {
3368 dequeue_task(p, rq->active);
3369 set_tsk_need_resched(p);
3370 p->prio = effective_prio(p);
3371 p->time_slice = task_timeslice(p);
3372 p->first_time_slice = 0;
3374 if (!rq->expired_timestamp)
3375 rq->expired_timestamp = jiffies;
3376 if (!TASK_INTERACTIVE(p) || expired_starving(rq)) {
3377 enqueue_task(p, rq->expired);
3378 if (p->static_prio < rq->best_expired_prio)
3379 rq->best_expired_prio = p->static_prio;
3381 enqueue_task(p, rq->active);
3384 * Prevent a too long timeslice allowing a task to monopolize
3385 * the CPU. We do this by splitting up the timeslice into
3388 * Note: this does not mean the task's timeslices expire or
3389 * get lost in any way, they just might be preempted by
3390 * another task of equal priority. (one with higher
3391 * priority would have preempted this task already.) We
3392 * requeue this task to the end of the list on this priority
3393 * level, which is in essence a round-robin of tasks with
3396 * This only applies to tasks in the interactive
3397 * delta range with at least TIMESLICE_GRANULARITY to requeue.
3399 if (TASK_INTERACTIVE(p) && !((task_timeslice(p) -
3400 p->time_slice) % TIMESLICE_GRANULARITY(p)) &&
3401 (p->time_slice >= TIMESLICE_GRANULARITY(p)) &&
3402 (p->array == rq->active)) {
3404 requeue_task(p, rq->active);
3405 set_tsk_need_resched(p);
3409 spin_unlock(&rq->lock);
3413 * This function gets called by the timer code, with HZ frequency.
3414 * We call it with interrupts disabled.
3416 * It also gets called by the fork code, when changing the parent's
3419 void scheduler_tick(void)
3421 struct task_struct *p = current;
3422 int cpu = smp_processor_id();
3423 int idle_at_tick = idle_cpu(cpu);
3424 struct rq *rq = cpu_rq(cpu);
3427 task_running_tick(rq, p);
3430 rq->idle_at_tick = idle_at_tick;
3431 trigger_load_balance(cpu);
3435 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3437 void fastcall add_preempt_count(int val)
3442 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3444 preempt_count() += val;
3446 * Spinlock count overflowing soon?
3448 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
3451 EXPORT_SYMBOL(add_preempt_count);
3453 void fastcall sub_preempt_count(int val)
3458 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3461 * Is the spinlock portion underflowing?
3463 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3464 !(preempt_count() & PREEMPT_MASK)))
3467 preempt_count() -= val;
3469 EXPORT_SYMBOL(sub_preempt_count);
3474 * schedule() is the main scheduler function.
3476 asmlinkage void __sched schedule(void)
3478 struct task_struct *prev, *next;
3479 struct prio_array *array;
3480 struct list_head *queue;
3481 unsigned long long now;
3482 unsigned long run_time;
3488 * Test if we are atomic. Since do_exit() needs to call into
3489 * schedule() atomically, we ignore that path for now.
3490 * Otherwise, whine if we are scheduling when we should not be.
3492 if (unlikely(in_atomic() && !current->exit_state)) {
3493 printk(KERN_ERR "BUG: scheduling while atomic: "
3495 current->comm, preempt_count(), current->pid);
3496 debug_show_held_locks(current);
3497 if (irqs_disabled())
3498 print_irqtrace_events(current);
3501 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3506 release_kernel_lock(prev);
3507 need_resched_nonpreemptible:
3511 * The idle thread is not allowed to schedule!
3512 * Remove this check after it has been exercised a bit.
3514 if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) {
3515 printk(KERN_ERR "bad: scheduling from the idle thread!\n");
3519 schedstat_inc(rq, sched_cnt);
3520 now = sched_clock();
3521 if (likely((long long)(now - prev->timestamp) < NS_MAX_SLEEP_AVG)) {
3522 run_time = now - prev->timestamp;
3523 if (unlikely((long long)(now - prev->timestamp) < 0))
3526 run_time = NS_MAX_SLEEP_AVG;
3529 * Tasks charged proportionately less run_time at high sleep_avg to
3530 * delay them losing their interactive status
3532 run_time /= (CURRENT_BONUS(prev) ? : 1);
3534 spin_lock_irq(&rq->lock);
3536 switch_count = &prev->nivcsw;
3537 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
3538 switch_count = &prev->nvcsw;
3539 if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
3540 unlikely(signal_pending(prev))))
3541 prev->state = TASK_RUNNING;
3543 if (prev->state == TASK_UNINTERRUPTIBLE)
3544 rq->nr_uninterruptible++;
3545 deactivate_task(prev, rq);
3549 cpu = smp_processor_id();
3550 if (unlikely(!rq->nr_running)) {
3551 idle_balance(cpu, rq);
3552 if (!rq->nr_running) {
3554 rq->expired_timestamp = 0;
3560 if (unlikely(!array->nr_active)) {
3562 * Switch the active and expired arrays.
3564 schedstat_inc(rq, sched_switch);
3565 rq->active = rq->expired;
3566 rq->expired = array;
3568 rq->expired_timestamp = 0;
3569 rq->best_expired_prio = MAX_PRIO;
3572 idx = sched_find_first_bit(array->bitmap);
3573 queue = array->queue + idx;
3574 next = list_entry(queue->next, struct task_struct, run_list);
3577 if (next == rq->idle)
3578 schedstat_inc(rq, sched_goidle);
3580 prefetch_stack(next);
3581 clear_tsk_need_resched(prev);
3582 rcu_qsctr_inc(task_cpu(prev));
3584 prev->sleep_avg -= run_time;
3585 if ((long)prev->sleep_avg <= 0)
3586 prev->sleep_avg = 0;
3587 prev->timestamp = prev->last_ran = now;
3589 sched_info_switch(prev, next);
3590 if (likely(prev != next)) {
3591 next->timestamp = next->last_ran = now;
3596 prepare_task_switch(rq, next);
3597 prev = context_switch(rq, prev, next);
3600 * this_rq must be evaluated again because prev may have moved
3601 * CPUs since it called schedule(), thus the 'rq' on its stack
3602 * frame will be invalid.
3604 finish_task_switch(this_rq(), prev);
3606 spin_unlock_irq(&rq->lock);
3609 if (unlikely(reacquire_kernel_lock(prev) < 0))
3610 goto need_resched_nonpreemptible;
3611 preempt_enable_no_resched();
3612 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3615 EXPORT_SYMBOL(schedule);
3617 #ifdef CONFIG_PREEMPT
3619 * this is the entry point to schedule() from in-kernel preemption
3620 * off of preempt_enable. Kernel preemptions off return from interrupt
3621 * occur there and call schedule directly.
3623 asmlinkage void __sched preempt_schedule(void)
3625 struct thread_info *ti = current_thread_info();
3626 #ifdef CONFIG_PREEMPT_BKL
3627 struct task_struct *task = current;
3628 int saved_lock_depth;
3631 * If there is a non-zero preempt_count or interrupts are disabled,
3632 * we do not want to preempt the current task. Just return..
3634 if (likely(ti->preempt_count || irqs_disabled()))
3638 add_preempt_count(PREEMPT_ACTIVE);
3640 * We keep the big kernel semaphore locked, but we
3641 * clear ->lock_depth so that schedule() doesnt
3642 * auto-release the semaphore:
3644 #ifdef CONFIG_PREEMPT_BKL
3645 saved_lock_depth = task->lock_depth;
3646 task->lock_depth = -1;
3649 #ifdef CONFIG_PREEMPT_BKL
3650 task->lock_depth = saved_lock_depth;
3652 sub_preempt_count(PREEMPT_ACTIVE);
3654 /* we could miss a preemption opportunity between schedule and now */
3656 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3659 EXPORT_SYMBOL(preempt_schedule);
3662 * this is the entry point to schedule() from kernel preemption
3663 * off of irq context.
3664 * Note, that this is called and return with irqs disabled. This will
3665 * protect us against recursive calling from irq.
3667 asmlinkage void __sched preempt_schedule_irq(void)
3669 struct thread_info *ti = current_thread_info();
3670 #ifdef CONFIG_PREEMPT_BKL
3671 struct task_struct *task = current;
3672 int saved_lock_depth;
3674 /* Catch callers which need to be fixed */
3675 BUG_ON(ti->preempt_count || !irqs_disabled());
3678 add_preempt_count(PREEMPT_ACTIVE);
3680 * We keep the big kernel semaphore locked, but we
3681 * clear ->lock_depth so that schedule() doesnt
3682 * auto-release the semaphore:
3684 #ifdef CONFIG_PREEMPT_BKL
3685 saved_lock_depth = task->lock_depth;
3686 task->lock_depth = -1;
3690 local_irq_disable();
3691 #ifdef CONFIG_PREEMPT_BKL
3692 task->lock_depth = saved_lock_depth;
3694 sub_preempt_count(PREEMPT_ACTIVE);
3696 /* we could miss a preemption opportunity between schedule and now */
3698 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3702 #endif /* CONFIG_PREEMPT */
3704 int default_wake_function(wait_queue_t *curr, unsigned mode, int sync,
3707 return try_to_wake_up(curr->private, mode, sync);
3709 EXPORT_SYMBOL(default_wake_function);
3712 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3713 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3714 * number) then we wake all the non-exclusive tasks and one exclusive task.
3716 * There are circumstances in which we can try to wake a task which has already
3717 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3718 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3720 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
3721 int nr_exclusive, int sync, void *key)
3723 struct list_head *tmp, *next;
3725 list_for_each_safe(tmp, next, &q->task_list) {
3726 wait_queue_t *curr = list_entry(tmp, wait_queue_t, task_list);
3727 unsigned flags = curr->flags;
3729 if (curr->func(curr, mode, sync, key) &&
3730 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
3736 * __wake_up - wake up threads blocked on a waitqueue.
3738 * @mode: which threads
3739 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3740 * @key: is directly passed to the wakeup function
3742 void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
3743 int nr_exclusive, void *key)
3745 unsigned long flags;
3747 spin_lock_irqsave(&q->lock, flags);
3748 __wake_up_common(q, mode, nr_exclusive, 0, key);
3749 spin_unlock_irqrestore(&q->lock, flags);
3751 EXPORT_SYMBOL(__wake_up);
3754 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3756 void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
3758 __wake_up_common(q, mode, 1, 0, NULL);
3762 * __wake_up_sync - wake up threads blocked on a waitqueue.
3764 * @mode: which threads
3765 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3767 * The sync wakeup differs that the waker knows that it will schedule
3768 * away soon, so while the target thread will be woken up, it will not
3769 * be migrated to another CPU - ie. the two threads are 'synchronized'
3770 * with each other. This can prevent needless bouncing between CPUs.
3772 * On UP it can prevent extra preemption.
3775 __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
3777 unsigned long flags;
3783 if (unlikely(!nr_exclusive))
3786 spin_lock_irqsave(&q->lock, flags);
3787 __wake_up_common(q, mode, nr_exclusive, sync, NULL);
3788 spin_unlock_irqrestore(&q->lock, flags);
3790 EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
3792 void fastcall complete(struct completion *x)
3794 unsigned long flags;
3796 spin_lock_irqsave(&x->wait.lock, flags);
3798 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3800 spin_unlock_irqrestore(&x->wait.lock, flags);
3802 EXPORT_SYMBOL(complete);
3804 void fastcall complete_all(struct completion *x)
3806 unsigned long flags;
3808 spin_lock_irqsave(&x->wait.lock, flags);
3809 x->done += UINT_MAX/2;
3810 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3812 spin_unlock_irqrestore(&x->wait.lock, flags);
3814 EXPORT_SYMBOL(complete_all);
3816 void fastcall __sched wait_for_completion(struct completion *x)
3820 spin_lock_irq(&x->wait.lock);
3822 DECLARE_WAITQUEUE(wait, current);
3824 wait.flags |= WQ_FLAG_EXCLUSIVE;
3825 __add_wait_queue_tail(&x->wait, &wait);
3827 __set_current_state(TASK_UNINTERRUPTIBLE);
3828 spin_unlock_irq(&x->wait.lock);
3830 spin_lock_irq(&x->wait.lock);
3832 __remove_wait_queue(&x->wait, &wait);
3835 spin_unlock_irq(&x->wait.lock);
3837 EXPORT_SYMBOL(wait_for_completion);
3839 unsigned long fastcall __sched
3840 wait_for_completion_timeout(struct completion *x, unsigned long timeout)
3844 spin_lock_irq(&x->wait.lock);
3846 DECLARE_WAITQUEUE(wait, current);
3848 wait.flags |= WQ_FLAG_EXCLUSIVE;
3849 __add_wait_queue_tail(&x->wait, &wait);
3851 __set_current_state(TASK_UNINTERRUPTIBLE);
3852 spin_unlock_irq(&x->wait.lock);
3853 timeout = schedule_timeout(timeout);
3854 spin_lock_irq(&x->wait.lock);
3856 __remove_wait_queue(&x->wait, &wait);
3860 __remove_wait_queue(&x->wait, &wait);
3864 spin_unlock_irq(&x->wait.lock);
3867 EXPORT_SYMBOL(wait_for_completion_timeout);
3869 int fastcall __sched wait_for_completion_interruptible(struct completion *x)
3875 spin_lock_irq(&x->wait.lock);
3877 DECLARE_WAITQUEUE(wait, current);
3879 wait.flags |= WQ_FLAG_EXCLUSIVE;
3880 __add_wait_queue_tail(&x->wait, &wait);
3882 if (signal_pending(current)) {
3884 __remove_wait_queue(&x->wait, &wait);
3887 __set_current_state(TASK_INTERRUPTIBLE);
3888 spin_unlock_irq(&x->wait.lock);
3890 spin_lock_irq(&x->wait.lock);
3892 __remove_wait_queue(&x->wait, &wait);
3896 spin_unlock_irq(&x->wait.lock);
3900 EXPORT_SYMBOL(wait_for_completion_interruptible);
3902 unsigned long fastcall __sched
3903 wait_for_completion_interruptible_timeout(struct completion *x,
3904 unsigned long timeout)
3908 spin_lock_irq(&x->wait.lock);
3910 DECLARE_WAITQUEUE(wait, current);
3912 wait.flags |= WQ_FLAG_EXCLUSIVE;
3913 __add_wait_queue_tail(&x->wait, &wait);
3915 if (signal_pending(current)) {
3916 timeout = -ERESTARTSYS;
3917 __remove_wait_queue(&x->wait, &wait);
3920 __set_current_state(TASK_INTERRUPTIBLE);
3921 spin_unlock_irq(&x->wait.lock);
3922 timeout = schedule_timeout(timeout);
3923 spin_lock_irq(&x->wait.lock);
3925 __remove_wait_queue(&x->wait, &wait);
3929 __remove_wait_queue(&x->wait, &wait);
3933 spin_unlock_irq(&x->wait.lock);
3936 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
3939 #define SLEEP_ON_VAR \
3940 unsigned long flags; \
3941 wait_queue_t wait; \
3942 init_waitqueue_entry(&wait, current);
3944 #define SLEEP_ON_HEAD \
3945 spin_lock_irqsave(&q->lock,flags); \
3946 __add_wait_queue(q, &wait); \
3947 spin_unlock(&q->lock);
3949 #define SLEEP_ON_TAIL \
3950 spin_lock_irq(&q->lock); \
3951 __remove_wait_queue(q, &wait); \
3952 spin_unlock_irqrestore(&q->lock, flags);
3954 void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q)
3958 current->state = TASK_INTERRUPTIBLE;
3964 EXPORT_SYMBOL(interruptible_sleep_on);
3966 long fastcall __sched
3967 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
3971 current->state = TASK_INTERRUPTIBLE;
3974 timeout = schedule_timeout(timeout);
3979 EXPORT_SYMBOL(interruptible_sleep_on_timeout);
3981 void fastcall __sched sleep_on(wait_queue_head_t *q)
3985 current->state = TASK_UNINTERRUPTIBLE;
3991 EXPORT_SYMBOL(sleep_on);
3993 long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
3997 current->state = TASK_UNINTERRUPTIBLE;
4000 timeout = schedule_timeout(timeout);
4006 EXPORT_SYMBOL(sleep_on_timeout);
4008 #ifdef CONFIG_RT_MUTEXES
4011 * rt_mutex_setprio - set the current priority of a task
4013 * @prio: prio value (kernel-internal form)
4015 * This function changes the 'effective' priority of a task. It does
4016 * not touch ->normal_prio like __setscheduler().
4018 * Used by the rt_mutex code to implement priority inheritance logic.
4020 void rt_mutex_setprio(struct task_struct *p, int prio)
4022 struct prio_array *array;
4023 unsigned long flags;
4027 BUG_ON(prio < 0 || prio > MAX_PRIO);
4029 rq = task_rq_lock(p, &flags);
4034 dequeue_task(p, array);
4039 * If changing to an RT priority then queue it
4040 * in the active array!
4044 enqueue_task(p, array);
4046 * Reschedule if we are currently running on this runqueue and
4047 * our priority decreased, or if we are not currently running on
4048 * this runqueue and our priority is higher than the current's
4050 if (task_running(rq, p)) {
4051 if (p->prio > oldprio)
4052 resched_task(rq->curr);
4053 } else if (TASK_PREEMPTS_CURR(p, rq))
4054 resched_task(rq->curr);
4056 task_rq_unlock(rq, &flags);
4061 void set_user_nice(struct task_struct *p, long nice)
4063 struct prio_array *array;
4064 int old_prio, delta;
4065 unsigned long flags;
4068 if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
4071 * We have to be careful, if called from sys_setpriority(),
4072 * the task might be in the middle of scheduling on another CPU.
4074 rq = task_rq_lock(p, &flags);
4076 * The RT priorities are set via sched_setscheduler(), but we still
4077 * allow the 'normal' nice value to be set - but as expected
4078 * it wont have any effect on scheduling until the task is
4079 * not SCHED_NORMAL/SCHED_BATCH:
4081 if (task_has_rt_policy(p)) {
4082 p->static_prio = NICE_TO_PRIO(nice);
4087 dequeue_task(p, array);
4088 dec_raw_weighted_load(rq, p);
4091 p->static_prio = NICE_TO_PRIO(nice);
4094 p->prio = effective_prio(p);
4095 delta = p->prio - old_prio;
4098 enqueue_task(p, array);
4099 inc_raw_weighted_load(rq, p);
4101 * If the task increased its priority or is running and
4102 * lowered its priority, then reschedule its CPU:
4104 if (delta < 0 || (delta > 0 && task_running(rq, p)))
4105 resched_task(rq->curr);
4108 task_rq_unlock(rq, &flags);
4110 EXPORT_SYMBOL(set_user_nice);
4113 * can_nice - check if a task can reduce its nice value
4117 int can_nice(const struct task_struct *p, const int nice)
4119 /* convert nice value [19,-20] to rlimit style value [1,40] */
4120 int nice_rlim = 20 - nice;
4122 return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
4123 capable(CAP_SYS_NICE));
4126 #ifdef __ARCH_WANT_SYS_NICE
4129 * sys_nice - change the priority of the current process.
4130 * @increment: priority increment
4132 * sys_setpriority is a more generic, but much slower function that
4133 * does similar things.
4135 asmlinkage long sys_nice(int increment)
4140 * Setpriority might change our priority at the same moment.
4141 * We don't have to worry. Conceptually one call occurs first
4142 * and we have a single winner.
4144 if (increment < -40)
4149 nice = PRIO_TO_NICE(current->static_prio) + increment;
4155 if (increment < 0 && !can_nice(current, nice))
4158 retval = security_task_setnice(current, nice);
4162 set_user_nice(current, nice);
4169 * task_prio - return the priority value of a given task.
4170 * @p: the task in question.
4172 * This is the priority value as seen by users in /proc.
4173 * RT tasks are offset by -200. Normal tasks are centered
4174 * around 0, value goes from -16 to +15.
4176 int task_prio(const struct task_struct *p)
4178 return p->prio - MAX_RT_PRIO;
4182 * task_nice - return the nice value of a given task.
4183 * @p: the task in question.
4185 int task_nice(const struct task_struct *p)
4187 return TASK_NICE(p);
4189 EXPORT_SYMBOL_GPL(task_nice);
4192 * idle_cpu - is a given cpu idle currently?
4193 * @cpu: the processor in question.
4195 int idle_cpu(int cpu)
4197 return cpu_curr(cpu) == cpu_rq(cpu)->idle;
4201 * idle_task - return the idle task for a given cpu.
4202 * @cpu: the processor in question.
4204 struct task_struct *idle_task(int cpu)
4206 return cpu_rq(cpu)->idle;
4210 * find_process_by_pid - find a process with a matching PID value.
4211 * @pid: the pid in question.
4213 static inline struct task_struct *find_process_by_pid(pid_t pid)
4215 return pid ? find_task_by_pid(pid) : current;
4218 /* Actually do priority change: must hold rq lock. */
4219 static void __setscheduler(struct task_struct *p, int policy, int prio)
4224 p->rt_priority = prio;
4225 p->normal_prio = normal_prio(p);
4226 /* we are holding p->pi_lock already */
4227 p->prio = rt_mutex_getprio(p);
4229 * SCHED_BATCH tasks are treated as perpetual CPU hogs:
4231 if (policy == SCHED_BATCH)
4237 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4238 * @p: the task in question.
4239 * @policy: new policy.
4240 * @param: structure containing the new RT priority.
4242 * NOTE that the task may be already dead.
4244 int sched_setscheduler(struct task_struct *p, int policy,
4245 struct sched_param *param)
4247 int retval, oldprio, oldpolicy = -1;
4248 struct prio_array *array;
4249 unsigned long flags;
4252 /* may grab non-irq protected spin_locks */
4253 BUG_ON(in_interrupt());
4255 /* double check policy once rq lock held */
4257 policy = oldpolicy = p->policy;
4258 else if (policy != SCHED_FIFO && policy != SCHED_RR &&
4259 policy != SCHED_NORMAL && policy != SCHED_BATCH)
4262 * Valid priorities for SCHED_FIFO and SCHED_RR are
4263 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
4266 if (param->sched_priority < 0 ||
4267 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
4268 (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
4270 if (rt_policy(policy) != (param->sched_priority != 0))
4274 * Allow unprivileged RT tasks to decrease priority:
4276 if (!capable(CAP_SYS_NICE)) {
4277 if (rt_policy(policy)) {
4278 unsigned long rlim_rtprio;
4279 unsigned long flags;
4281 if (!lock_task_sighand(p, &flags))
4283 rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
4284 unlock_task_sighand(p, &flags);
4286 /* can't set/change the rt policy */
4287 if (policy != p->policy && !rlim_rtprio)
4290 /* can't increase priority */
4291 if (param->sched_priority > p->rt_priority &&
4292 param->sched_priority > rlim_rtprio)
4296 /* can't change other user's priorities */
4297 if ((current->euid != p->euid) &&
4298 (current->euid != p->uid))
4302 retval = security_task_setscheduler(p, policy, param);
4306 * make sure no PI-waiters arrive (or leave) while we are
4307 * changing the priority of the task:
4309 spin_lock_irqsave(&p->pi_lock, flags);
4311 * To be able to change p->policy safely, the apropriate
4312 * runqueue lock must be held.
4314 rq = __task_rq_lock(p);
4315 /* recheck policy now with rq lock held */
4316 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
4317 policy = oldpolicy = -1;
4318 __task_rq_unlock(rq);
4319 spin_unlock_irqrestore(&p->pi_lock, flags);
4324 deactivate_task(p, rq);
4326 __setscheduler(p, policy, param->sched_priority);
4328 __activate_task(p, rq);
4330 * Reschedule if we are currently running on this runqueue and
4331 * our priority decreased, or if we are not currently running on
4332 * this runqueue and our priority is higher than the current's
4334 if (task_running(rq, p)) {
4335 if (p->prio > oldprio)
4336 resched_task(rq->curr);
4337 } else if (TASK_PREEMPTS_CURR(p, rq))
4338 resched_task(rq->curr);
4340 __task_rq_unlock(rq);
4341 spin_unlock_irqrestore(&p->pi_lock, flags);
4343 rt_mutex_adjust_pi(p);
4347 EXPORT_SYMBOL_GPL(sched_setscheduler);
4350 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4352 struct sched_param lparam;
4353 struct task_struct *p;
4356 if (!param || pid < 0)
4358 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4363 p = find_process_by_pid(pid);
4365 retval = sched_setscheduler(p, policy, &lparam);
4372 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4373 * @pid: the pid in question.
4374 * @policy: new policy.
4375 * @param: structure containing the new RT priority.
4377 asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
4378 struct sched_param __user *param)
4380 /* negative values for policy are not valid */
4384 return do_sched_setscheduler(pid, policy, param);
4388 * sys_sched_setparam - set/change the RT priority of a thread
4389 * @pid: the pid in question.
4390 * @param: structure containing the new RT priority.
4392 asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
4394 return do_sched_setscheduler(pid, -1, param);
4398 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4399 * @pid: the pid in question.
4401 asmlinkage long sys_sched_getscheduler(pid_t pid)
4403 struct task_struct *p;
4404 int retval = -EINVAL;
4410 read_lock(&tasklist_lock);
4411 p = find_process_by_pid(pid);
4413 retval = security_task_getscheduler(p);
4417 read_unlock(&tasklist_lock);
4424 * sys_sched_getscheduler - get the RT priority of a thread
4425 * @pid: the pid in question.
4426 * @param: structure containing the RT priority.
4428 asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
4430 struct sched_param lp;
4431 struct task_struct *p;
4432 int retval = -EINVAL;
4434 if (!param || pid < 0)
4437 read_lock(&tasklist_lock);
4438 p = find_process_by_pid(pid);
4443 retval = security_task_getscheduler(p);
4447 lp.sched_priority = p->rt_priority;
4448 read_unlock(&tasklist_lock);
4451 * This one might sleep, we cannot do it with a spinlock held ...
4453 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4459 read_unlock(&tasklist_lock);
4463 long sched_setaffinity(pid_t pid, cpumask_t new_mask)
4465 cpumask_t cpus_allowed;
4466 struct task_struct *p;
4469 mutex_lock(&sched_hotcpu_mutex);
4470 read_lock(&tasklist_lock);
4472 p = find_process_by_pid(pid);
4474 read_unlock(&tasklist_lock);
4475 mutex_unlock(&sched_hotcpu_mutex);
4480 * It is not safe to call set_cpus_allowed with the
4481 * tasklist_lock held. We will bump the task_struct's
4482 * usage count and then drop tasklist_lock.
4485 read_unlock(&tasklist_lock);
4488 if ((current->euid != p->euid) && (current->euid != p->uid) &&
4489 !capable(CAP_SYS_NICE))
4492 retval = security_task_setscheduler(p, 0, NULL);
4496 cpus_allowed = cpuset_cpus_allowed(p);
4497 cpus_and(new_mask, new_mask, cpus_allowed);
4498 retval = set_cpus_allowed(p, new_mask);
4502 mutex_unlock(&sched_hotcpu_mutex);
4506 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4507 cpumask_t *new_mask)
4509 if (len < sizeof(cpumask_t)) {
4510 memset(new_mask, 0, sizeof(cpumask_t));
4511 } else if (len > sizeof(cpumask_t)) {
4512 len = sizeof(cpumask_t);
4514 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4518 * sys_sched_setaffinity - set the cpu affinity of a process
4519 * @pid: pid of the process
4520 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4521 * @user_mask_ptr: user-space pointer to the new cpu mask
4523 asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
4524 unsigned long __user *user_mask_ptr)
4529 retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
4533 return sched_setaffinity(pid, new_mask);
4537 * Represents all cpu's present in the system
4538 * In systems capable of hotplug, this map could dynamically grow
4539 * as new cpu's are detected in the system via any platform specific
4540 * method, such as ACPI for e.g.
4543 cpumask_t cpu_present_map __read_mostly;
4544 EXPORT_SYMBOL(cpu_present_map);
4547 cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
4548 EXPORT_SYMBOL(cpu_online_map);
4550 cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
4551 EXPORT_SYMBOL(cpu_possible_map);
4554 long sched_getaffinity(pid_t pid, cpumask_t *mask)
4556 struct task_struct *p;
4559 mutex_lock(&sched_hotcpu_mutex);
4560 read_lock(&tasklist_lock);
4563 p = find_process_by_pid(pid);
4567 retval = security_task_getscheduler(p);
4571 cpus_and(*mask, p->cpus_allowed, cpu_online_map);
4574 read_unlock(&tasklist_lock);
4575 mutex_unlock(&sched_hotcpu_mutex);
4583 * sys_sched_getaffinity - get the cpu affinity of a process
4584 * @pid: pid of the process
4585 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4586 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4588 asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
4589 unsigned long __user *user_mask_ptr)
4594 if (len < sizeof(cpumask_t))
4597 ret = sched_getaffinity(pid, &mask);
4601 if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
4604 return sizeof(cpumask_t);
4608 * sys_sched_yield - yield the current processor to other threads.
4610 * This function yields the current CPU by moving the calling thread
4611 * to the expired array. If there are no other threads running on this
4612 * CPU then this function will return.
4614 asmlinkage long sys_sched_yield(void)
4616 struct rq *rq = this_rq_lock();
4617 struct prio_array *array = current->array, *target = rq->expired;
4619 schedstat_inc(rq, yld_cnt);
4621 * We implement yielding by moving the task into the expired
4624 * (special rule: RT tasks will just roundrobin in the active
4627 if (rt_task(current))
4628 target = rq->active;
4630 if (array->nr_active == 1) {
4631 schedstat_inc(rq, yld_act_empty);
4632 if (!rq->expired->nr_active)
4633 schedstat_inc(rq, yld_both_empty);
4634 } else if (!rq->expired->nr_active)
4635 schedstat_inc(rq, yld_exp_empty);
4637 if (array != target) {
4638 dequeue_task(current, array);
4639 enqueue_task(current, target);
4642 * requeue_task is cheaper so perform that if possible.
4644 requeue_task(current, array);
4647 * Since we are going to call schedule() anyway, there's
4648 * no need to preempt or enable interrupts:
4650 __release(rq->lock);
4651 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4652 _raw_spin_unlock(&rq->lock);
4653 preempt_enable_no_resched();
4660 static void __cond_resched(void)
4662 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4663 __might_sleep(__FILE__, __LINE__);
4666 * The BKS might be reacquired before we have dropped
4667 * PREEMPT_ACTIVE, which could trigger a second
4668 * cond_resched() call.
4671 add_preempt_count(PREEMPT_ACTIVE);
4673 sub_preempt_count(PREEMPT_ACTIVE);
4674 } while (need_resched());
4677 int __sched cond_resched(void)
4679 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&
4680 system_state == SYSTEM_RUNNING) {
4686 EXPORT_SYMBOL(cond_resched);
4689 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4690 * call schedule, and on return reacquire the lock.
4692 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4693 * operations here to prevent schedule() from being called twice (once via
4694 * spin_unlock(), once by hand).
4696 int cond_resched_lock(spinlock_t *lock)
4700 if (need_lockbreak(lock)) {
4706 if (need_resched() && system_state == SYSTEM_RUNNING) {
4707 spin_release(&lock->dep_map, 1, _THIS_IP_);
4708 _raw_spin_unlock(lock);
4709 preempt_enable_no_resched();
4716 EXPORT_SYMBOL(cond_resched_lock);
4718 int __sched cond_resched_softirq(void)
4720 BUG_ON(!in_softirq());
4722 if (need_resched() && system_state == SYSTEM_RUNNING) {
4730 EXPORT_SYMBOL(cond_resched_softirq);
4733 * yield - yield the current processor to other threads.
4735 * This is a shortcut for kernel-space yielding - it marks the
4736 * thread runnable and calls sys_sched_yield().
4738 void __sched yield(void)
4740 set_current_state(TASK_RUNNING);
4743 EXPORT_SYMBOL(yield);
4746 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4747 * that process accounting knows that this is a task in IO wait state.
4749 * But don't do that if it is a deliberate, throttling IO wait (this task
4750 * has set its backing_dev_info: the queue against which it should throttle)
4752 void __sched io_schedule(void)
4754 struct rq *rq = &__raw_get_cpu_var(runqueues);
4756 delayacct_blkio_start();
4757 atomic_inc(&rq->nr_iowait);
4759 atomic_dec(&rq->nr_iowait);
4760 delayacct_blkio_end();
4762 EXPORT_SYMBOL(io_schedule);
4764 long __sched io_schedule_timeout(long timeout)
4766 struct rq *rq = &__raw_get_cpu_var(runqueues);
4769 delayacct_blkio_start();
4770 atomic_inc(&rq->nr_iowait);
4771 ret = schedule_timeout(timeout);
4772 atomic_dec(&rq->nr_iowait);
4773 delayacct_blkio_end();
4778 * sys_sched_get_priority_max - return maximum RT priority.
4779 * @policy: scheduling class.
4781 * this syscall returns the maximum rt_priority that can be used
4782 * by a given scheduling class.
4784 asmlinkage long sys_sched_get_priority_max(int policy)
4791 ret = MAX_USER_RT_PRIO-1;
4802 * sys_sched_get_priority_min - return minimum RT priority.
4803 * @policy: scheduling class.
4805 * this syscall returns the minimum rt_priority that can be used
4806 * by a given scheduling class.
4808 asmlinkage long sys_sched_get_priority_min(int policy)
4825 * sys_sched_rr_get_interval - return the default timeslice of a process.
4826 * @pid: pid of the process.
4827 * @interval: userspace pointer to the timeslice value.
4829 * this syscall writes the default timeslice value of a given process
4830 * into the user-space timespec buffer. A value of '0' means infinity.
4833 long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
4835 struct task_struct *p;
4836 int retval = -EINVAL;
4843 read_lock(&tasklist_lock);
4844 p = find_process_by_pid(pid);
4848 retval = security_task_getscheduler(p);
4852 jiffies_to_timespec(p->policy == SCHED_FIFO ?
4853 0 : task_timeslice(p), &t);
4854 read_unlock(&tasklist_lock);
4855 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4859 read_unlock(&tasklist_lock);
4863 static const char stat_nam[] = "RSDTtZX";
4865 static void show_task(struct task_struct *p)
4867 unsigned long free = 0;
4870 state = p->state ? __ffs(p->state) + 1 : 0;
4871 printk("%-13.13s %c", p->comm,
4872 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4873 #if (BITS_PER_LONG == 32)
4874 if (state == TASK_RUNNING)
4875 printk(" running ");
4877 printk(" %08lX ", thread_saved_pc(p));
4879 if (state == TASK_RUNNING)
4880 printk(" running task ");
4882 printk(" %016lx ", thread_saved_pc(p));
4884 #ifdef CONFIG_DEBUG_STACK_USAGE
4886 unsigned long *n = end_of_stack(p);
4889 free = (unsigned long)n - (unsigned long)end_of_stack(p);
4892 printk("%5lu %5d %6d", free, p->pid, p->parent->pid);
4894 printk(" (L-TLB)\n");
4896 printk(" (NOTLB)\n");
4898 if (state != TASK_RUNNING)
4899 show_stack(p, NULL);
4902 void show_state_filter(unsigned long state_filter)
4904 struct task_struct *g, *p;
4906 #if (BITS_PER_LONG == 32)
4909 printk(" task PC stack pid father child younger older\n");
4913 printk(" task PC stack pid father child younger older\n");
4915 read_lock(&tasklist_lock);
4916 do_each_thread(g, p) {
4918 * reset the NMI-timeout, listing all files on a slow
4919 * console might take alot of time:
4921 touch_nmi_watchdog();
4922 if (!state_filter || (p->state & state_filter))
4924 } while_each_thread(g, p);
4926 touch_all_softlockup_watchdogs();
4928 read_unlock(&tasklist_lock);
4930 * Only show locks if all tasks are dumped:
4932 if (state_filter == -1)
4933 debug_show_all_locks();
4936 void __cpuinit init_idle_bootup_task(struct task_struct *idle)
4942 * init_idle - set up an idle thread for a given CPU
4943 * @idle: task in question
4944 * @cpu: cpu the idle task belongs to
4946 * NOTE: this function does not set the idle thread's NEED_RESCHED
4947 * flag, to make booting more robust.
4949 void __cpuinit init_idle(struct task_struct *idle, int cpu)
4951 struct rq *rq = cpu_rq(cpu);
4952 unsigned long flags;
4954 idle->timestamp = sched_clock();
4955 idle->sleep_avg = 0;
4957 idle->prio = idle->normal_prio = MAX_PRIO;
4958 idle->state = TASK_RUNNING;
4959 idle->cpus_allowed = cpumask_of_cpu(cpu);
4960 set_task_cpu(idle, cpu);
4962 spin_lock_irqsave(&rq->lock, flags);
4963 rq->curr = rq->idle = idle;
4964 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4967 spin_unlock_irqrestore(&rq->lock, flags);
4969 /* Set the preempt count _outside_ the spinlocks! */
4970 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4971 task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
4973 task_thread_info(idle)->preempt_count = 0;
4978 * In a system that switches off the HZ timer nohz_cpu_mask
4979 * indicates which cpus entered this state. This is used
4980 * in the rcu update to wait only for active cpus. For system
4981 * which do not switch off the HZ timer nohz_cpu_mask should
4982 * always be CPU_MASK_NONE.
4984 cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
4988 * This is how migration works:
4990 * 1) we queue a struct migration_req structure in the source CPU's
4991 * runqueue and wake up that CPU's migration thread.
4992 * 2) we down() the locked semaphore => thread blocks.
4993 * 3) migration thread wakes up (implicitly it forces the migrated
4994 * thread off the CPU)
4995 * 4) it gets the migration request and checks whether the migrated
4996 * task is still in the wrong runqueue.
4997 * 5) if it's in the wrong runqueue then the migration thread removes
4998 * it and puts it into the right queue.
4999 * 6) migration thread up()s the semaphore.
5000 * 7) we wake up and the migration is done.
5004 * Change a given task's CPU affinity. Migrate the thread to a
5005 * proper CPU and schedule it away if the CPU it's executing on
5006 * is removed from the allowed bitmask.
5008 * NOTE: the caller must have a valid reference to the task, the
5009 * task must not exit() & deallocate itself prematurely. The
5010 * call is not atomic; no spinlocks may be held.
5012 int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
5014 struct migration_req req;
5015 unsigned long flags;
5019 rq = task_rq_lock(p, &flags);
5020 if (!cpus_intersects(new_mask, cpu_online_map)) {
5025 p->cpus_allowed = new_mask;
5026 /* Can the task run on the task's current CPU? If so, we're done */
5027 if (cpu_isset(task_cpu(p), new_mask))
5030 if (migrate_task(p, any_online_cpu(new_mask), &req)) {
5031 /* Need help from migration thread: drop lock and wait. */
5032 task_rq_unlock(rq, &flags);
5033 wake_up_process(rq->migration_thread);
5034 wait_for_completion(&req.done);
5035 tlb_migrate_finish(p->mm);
5039 task_rq_unlock(rq, &flags);
5043 EXPORT_SYMBOL_GPL(set_cpus_allowed);
5046 * Move (not current) task off this cpu, onto dest cpu. We're doing
5047 * this because either it can't run here any more (set_cpus_allowed()
5048 * away from this CPU, or CPU going down), or because we're
5049 * attempting to rebalance this task on exec (sched_exec).
5051 * So we race with normal scheduler movements, but that's OK, as long
5052 * as the task is no longer on this CPU.
5054 * Returns non-zero if task was successfully migrated.
5056 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
5058 struct rq *rq_dest, *rq_src;
5061 if (unlikely(cpu_is_offline(dest_cpu)))
5064 rq_src = cpu_rq(src_cpu);
5065 rq_dest = cpu_rq(dest_cpu);
5067 double_rq_lock(rq_src, rq_dest);
5068 /* Already moved. */
5069 if (task_cpu(p) != src_cpu)
5071 /* Affinity changed (again). */
5072 if (!cpu_isset(dest_cpu, p->cpus_allowed))
5075 set_task_cpu(p, dest_cpu);
5078 * Sync timestamp with rq_dest's before activating.
5079 * The same thing could be achieved by doing this step
5080 * afterwards, and pretending it was a local activate.
5081 * This way is cleaner and logically correct.
5083 p->timestamp = p->timestamp - rq_src->most_recent_timestamp
5084 + rq_dest->most_recent_timestamp;
5085 deactivate_task(p, rq_src);
5086 __activate_task(p, rq_dest);
5087 if (TASK_PREEMPTS_CURR(p, rq_dest))
5088 resched_task(rq_dest->curr);
5092 double_rq_unlock(rq_src, rq_dest);
5097 * migration_thread - this is a highprio system thread that performs
5098 * thread migration by bumping thread off CPU then 'pushing' onto
5101 static int migration_thread(void *data)
5103 int cpu = (long)data;
5107 BUG_ON(rq->migration_thread != current);
5109 set_current_state(TASK_INTERRUPTIBLE);
5110 while (!kthread_should_stop()) {
5111 struct migration_req *req;
5112 struct list_head *head;
5116 spin_lock_irq(&rq->lock);
5118 if (cpu_is_offline(cpu)) {
5119 spin_unlock_irq(&rq->lock);
5123 if (rq->active_balance) {
5124 active_load_balance(rq, cpu);
5125 rq->active_balance = 0;
5128 head = &rq->migration_queue;
5130 if (list_empty(head)) {
5131 spin_unlock_irq(&rq->lock);
5133 set_current_state(TASK_INTERRUPTIBLE);
5136 req = list_entry(head->next, struct migration_req, list);
5137 list_del_init(head->next);
5139 spin_unlock(&rq->lock);
5140 __migrate_task(req->task, cpu, req->dest_cpu);
5143 complete(&req->done);
5145 __set_current_state(TASK_RUNNING);
5149 /* Wait for kthread_stop */
5150 set_current_state(TASK_INTERRUPTIBLE);
5151 while (!kthread_should_stop()) {
5153 set_current_state(TASK_INTERRUPTIBLE);
5155 __set_current_state(TASK_RUNNING);
5159 #ifdef CONFIG_HOTPLUG_CPU
5161 * Figure out where task on dead CPU should go, use force if neccessary.
5162 * NOTE: interrupts should be disabled by the caller
5164 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
5166 unsigned long flags;
5173 mask = node_to_cpumask(cpu_to_node(dead_cpu));
5174 cpus_and(mask, mask, p->cpus_allowed);
5175 dest_cpu = any_online_cpu(mask);
5177 /* On any allowed CPU? */
5178 if (dest_cpu == NR_CPUS)
5179 dest_cpu = any_online_cpu(p->cpus_allowed);
5181 /* No more Mr. Nice Guy. */
5182 if (dest_cpu == NR_CPUS) {
5183 rq = task_rq_lock(p, &flags);
5184 cpus_setall(p->cpus_allowed);
5185 dest_cpu = any_online_cpu(p->cpus_allowed);
5186 task_rq_unlock(rq, &flags);
5189 * Don't tell them about moving exiting tasks or
5190 * kernel threads (both mm NULL), since they never
5193 if (p->mm && printk_ratelimit())
5194 printk(KERN_INFO "process %d (%s) no "
5195 "longer affine to cpu%d\n",
5196 p->pid, p->comm, dead_cpu);
5198 if (!__migrate_task(p, dead_cpu, dest_cpu))
5203 * While a dead CPU has no uninterruptible tasks queued at this point,
5204 * it might still have a nonzero ->nr_uninterruptible counter, because
5205 * for performance reasons the counter is not stricly tracking tasks to
5206 * their home CPUs. So we just add the counter to another CPU's counter,
5207 * to keep the global sum constant after CPU-down:
5209 static void migrate_nr_uninterruptible(struct rq *rq_src)
5211 struct rq *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL));
5212 unsigned long flags;
5214 local_irq_save(flags);
5215 double_rq_lock(rq_src, rq_dest);
5216 rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
5217 rq_src->nr_uninterruptible = 0;
5218 double_rq_unlock(rq_src, rq_dest);
5219 local_irq_restore(flags);
5222 /* Run through task list and migrate tasks from the dead cpu. */
5223 static void migrate_live_tasks(int src_cpu)
5225 struct task_struct *p, *t;
5227 write_lock_irq(&tasklist_lock);
5229 do_each_thread(t, p) {
5233 if (task_cpu(p) == src_cpu)
5234 move_task_off_dead_cpu(src_cpu, p);
5235 } while_each_thread(t, p);
5237 write_unlock_irq(&tasklist_lock);
5240 /* Schedules idle task to be the next runnable task on current CPU.
5241 * It does so by boosting its priority to highest possible and adding it to
5242 * the _front_ of the runqueue. Used by CPU offline code.
5244 void sched_idle_next(void)
5246 int this_cpu = smp_processor_id();
5247 struct rq *rq = cpu_rq(this_cpu);
5248 struct task_struct *p = rq->idle;
5249 unsigned long flags;
5251 /* cpu has to be offline */
5252 BUG_ON(cpu_online(this_cpu));
5255 * Strictly not necessary since rest of the CPUs are stopped by now
5256 * and interrupts disabled on the current cpu.
5258 spin_lock_irqsave(&rq->lock, flags);
5260 __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
5262 /* Add idle task to the _front_ of its priority queue: */
5263 __activate_idle_task(p, rq);
5265 spin_unlock_irqrestore(&rq->lock, flags);
5269 * Ensures that the idle task is using init_mm right before its cpu goes
5272 void idle_task_exit(void)
5274 struct mm_struct *mm = current->active_mm;
5276 BUG_ON(cpu_online(smp_processor_id()));
5279 switch_mm(mm, &init_mm, current);
5283 /* called under rq->lock with disabled interrupts */
5284 static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
5286 struct rq *rq = cpu_rq(dead_cpu);
5288 /* Must be exiting, otherwise would be on tasklist. */
5289 BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD);
5291 /* Cannot have done final schedule yet: would have vanished. */
5292 BUG_ON(p->state == TASK_DEAD);
5297 * Drop lock around migration; if someone else moves it,
5298 * that's OK. No task can be added to this CPU, so iteration is
5300 * NOTE: interrupts should be left disabled --dev@
5302 spin_unlock(&rq->lock);
5303 move_task_off_dead_cpu(dead_cpu, p);
5304 spin_lock(&rq->lock);
5309 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5310 static void migrate_dead_tasks(unsigned int dead_cpu)
5312 struct rq *rq = cpu_rq(dead_cpu);
5313 unsigned int arr, i;
5315 for (arr = 0; arr < 2; arr++) {
5316 for (i = 0; i < MAX_PRIO; i++) {
5317 struct list_head *list = &rq->arrays[arr].queue[i];
5319 while (!list_empty(list))
5320 migrate_dead(dead_cpu, list_entry(list->next,
5321 struct task_struct, run_list));
5325 #endif /* CONFIG_HOTPLUG_CPU */
5328 * migration_call - callback that gets triggered when a CPU is added.
5329 * Here we can start up the necessary migration thread for the new CPU.
5331 static int __cpuinit
5332 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5334 struct task_struct *p;
5335 int cpu = (long)hcpu;
5336 unsigned long flags;
5340 case CPU_LOCK_ACQUIRE:
5341 mutex_lock(&sched_hotcpu_mutex);
5344 case CPU_UP_PREPARE:
5345 case CPU_UP_PREPARE_FROZEN:
5346 p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
5349 p->flags |= PF_NOFREEZE;
5350 kthread_bind(p, cpu);
5351 /* Must be high prio: stop_machine expects to yield to it. */
5352 rq = task_rq_lock(p, &flags);
5353 __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
5354 task_rq_unlock(rq, &flags);
5355 cpu_rq(cpu)->migration_thread = p;
5359 case CPU_ONLINE_FROZEN:
5360 /* Strictly unneccessary, as first user will wake it. */
5361 wake_up_process(cpu_rq(cpu)->migration_thread);
5364 #ifdef CONFIG_HOTPLUG_CPU
5365 case CPU_UP_CANCELED:
5366 case CPU_UP_CANCELED_FROZEN:
5367 if (!cpu_rq(cpu)->migration_thread)
5369 /* Unbind it from offline cpu so it can run. Fall thru. */
5370 kthread_bind(cpu_rq(cpu)->migration_thread,
5371 any_online_cpu(cpu_online_map));
5372 kthread_stop(cpu_rq(cpu)->migration_thread);
5373 cpu_rq(cpu)->migration_thread = NULL;
5377 case CPU_DEAD_FROZEN:
5378 migrate_live_tasks(cpu);
5380 kthread_stop(rq->migration_thread);
5381 rq->migration_thread = NULL;
5382 /* Idle task back to normal (off runqueue, low prio) */
5383 rq = task_rq_lock(rq->idle, &flags);
5384 deactivate_task(rq->idle, rq);
5385 rq->idle->static_prio = MAX_PRIO;
5386 __setscheduler(rq->idle, SCHED_NORMAL, 0);
5387 migrate_dead_tasks(cpu);
5388 task_rq_unlock(rq, &flags);
5389 migrate_nr_uninterruptible(rq);
5390 BUG_ON(rq->nr_running != 0);
5392 /* No need to migrate the tasks: it was best-effort if
5393 * they didn't take sched_hotcpu_mutex. Just wake up
5394 * the requestors. */
5395 spin_lock_irq(&rq->lock);
5396 while (!list_empty(&rq->migration_queue)) {
5397 struct migration_req *req;
5399 req = list_entry(rq->migration_queue.next,
5400 struct migration_req, list);
5401 list_del_init(&req->list);
5402 complete(&req->done);
5404 spin_unlock_irq(&rq->lock);
5407 case CPU_LOCK_RELEASE:
5408 mutex_unlock(&sched_hotcpu_mutex);
5414 /* Register at highest priority so that task migration (migrate_all_tasks)
5415 * happens before everything else.
5417 static struct notifier_block __cpuinitdata migration_notifier = {
5418 .notifier_call = migration_call,
5422 int __init migration_init(void)
5424 void *cpu = (void *)(long)smp_processor_id();
5427 /* Start one for the boot CPU: */
5428 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5429 BUG_ON(err == NOTIFY_BAD);
5430 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5431 register_cpu_notifier(&migration_notifier);
5439 /* Number of possible processor ids */
5440 int nr_cpu_ids __read_mostly = NR_CPUS;
5441 EXPORT_SYMBOL(nr_cpu_ids);
5443 #undef SCHED_DOMAIN_DEBUG
5444 #ifdef SCHED_DOMAIN_DEBUG
5445 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5450 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5454 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5459 struct sched_group *group = sd->groups;
5460 cpumask_t groupmask;
5462 cpumask_scnprintf(str, NR_CPUS, sd->span);
5463 cpus_clear(groupmask);
5466 for (i = 0; i < level + 1; i++)
5468 printk("domain %d: ", level);
5470 if (!(sd->flags & SD_LOAD_BALANCE)) {
5471 printk("does not load-balance\n");
5473 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5478 printk("span %s\n", str);
5480 if (!cpu_isset(cpu, sd->span))
5481 printk(KERN_ERR "ERROR: domain->span does not contain "
5483 if (!cpu_isset(cpu, group->cpumask))
5484 printk(KERN_ERR "ERROR: domain->groups does not contain"
5488 for (i = 0; i < level + 2; i++)
5494 printk(KERN_ERR "ERROR: group is NULL\n");
5498 if (!group->__cpu_power) {
5500 printk(KERN_ERR "ERROR: domain->cpu_power not "
5504 if (!cpus_weight(group->cpumask)) {
5506 printk(KERN_ERR "ERROR: empty group\n");
5509 if (cpus_intersects(groupmask, group->cpumask)) {
5511 printk(KERN_ERR "ERROR: repeated CPUs\n");
5514 cpus_or(groupmask, groupmask, group->cpumask);
5516 cpumask_scnprintf(str, NR_CPUS, group->cpumask);
5519 group = group->next;
5520 } while (group != sd->groups);
5523 if (!cpus_equal(sd->span, groupmask))
5524 printk(KERN_ERR "ERROR: groups don't span "
5532 if (!cpus_subset(groupmask, sd->span))
5533 printk(KERN_ERR "ERROR: parent span is not a superset "
5534 "of domain->span\n");
5539 # define sched_domain_debug(sd, cpu) do { } while (0)
5542 static int sd_degenerate(struct sched_domain *sd)
5544 if (cpus_weight(sd->span) == 1)
5547 /* Following flags need at least 2 groups */
5548 if (sd->flags & (SD_LOAD_BALANCE |
5549 SD_BALANCE_NEWIDLE |
5553 SD_SHARE_PKG_RESOURCES)) {
5554 if (sd->groups != sd->groups->next)
5558 /* Following flags don't use groups */
5559 if (sd->flags & (SD_WAKE_IDLE |
5568 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5570 unsigned long cflags = sd->flags, pflags = parent->flags;
5572 if (sd_degenerate(parent))
5575 if (!cpus_equal(sd->span, parent->span))
5578 /* Does parent contain flags not in child? */
5579 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5580 if (cflags & SD_WAKE_AFFINE)
5581 pflags &= ~SD_WAKE_BALANCE;
5582 /* Flags needing groups don't count if only 1 group in parent */
5583 if (parent->groups == parent->groups->next) {
5584 pflags &= ~(SD_LOAD_BALANCE |
5585 SD_BALANCE_NEWIDLE |
5589 SD_SHARE_PKG_RESOURCES);
5591 if (~cflags & pflags)
5598 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5599 * hold the hotplug lock.
5601 static void cpu_attach_domain(struct sched_domain *sd, int cpu)
5603 struct rq *rq = cpu_rq(cpu);
5604 struct sched_domain *tmp;
5606 /* Remove the sched domains which do not contribute to scheduling. */
5607 for (tmp = sd; tmp; tmp = tmp->parent) {
5608 struct sched_domain *parent = tmp->parent;
5611 if (sd_parent_degenerate(tmp, parent)) {
5612 tmp->parent = parent->parent;
5614 parent->parent->child = tmp;
5618 if (sd && sd_degenerate(sd)) {
5624 sched_domain_debug(sd, cpu);
5626 rcu_assign_pointer(rq->sd, sd);
5629 /* cpus with isolated domains */
5630 static cpumask_t cpu_isolated_map = CPU_MASK_NONE;
5632 /* Setup the mask of cpus configured for isolated domains */
5633 static int __init isolated_cpu_setup(char *str)
5635 int ints[NR_CPUS], i;
5637 str = get_options(str, ARRAY_SIZE(ints), ints);
5638 cpus_clear(cpu_isolated_map);
5639 for (i = 1; i <= ints[0]; i++)
5640 if (ints[i] < NR_CPUS)
5641 cpu_set(ints[i], cpu_isolated_map);
5645 __setup ("isolcpus=", isolated_cpu_setup);
5648 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
5649 * to a function which identifies what group(along with sched group) a CPU
5650 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
5651 * (due to the fact that we keep track of groups covered with a cpumask_t).
5653 * init_sched_build_groups will build a circular linked list of the groups
5654 * covered by the given span, and will set each group's ->cpumask correctly,
5655 * and ->cpu_power to 0.
5658 init_sched_build_groups(cpumask_t span, const cpumask_t *cpu_map,
5659 int (*group_fn)(int cpu, const cpumask_t *cpu_map,
5660 struct sched_group **sg))
5662 struct sched_group *first = NULL, *last = NULL;
5663 cpumask_t covered = CPU_MASK_NONE;
5666 for_each_cpu_mask(i, span) {
5667 struct sched_group *sg;
5668 int group = group_fn(i, cpu_map, &sg);
5671 if (cpu_isset(i, covered))
5674 sg->cpumask = CPU_MASK_NONE;
5675 sg->__cpu_power = 0;
5677 for_each_cpu_mask(j, span) {
5678 if (group_fn(j, cpu_map, NULL) != group)
5681 cpu_set(j, covered);
5682 cpu_set(j, sg->cpumask);
5693 #define SD_NODES_PER_DOMAIN 16
5698 * find_next_best_node - find the next node to include in a sched_domain
5699 * @node: node whose sched_domain we're building
5700 * @used_nodes: nodes already in the sched_domain
5702 * Find the next node to include in a given scheduling domain. Simply
5703 * finds the closest node not already in the @used_nodes map.
5705 * Should use nodemask_t.
5707 static int find_next_best_node(int node, unsigned long *used_nodes)
5709 int i, n, val, min_val, best_node = 0;
5713 for (i = 0; i < MAX_NUMNODES; i++) {
5714 /* Start at @node */
5715 n = (node + i) % MAX_NUMNODES;
5717 if (!nr_cpus_node(n))
5720 /* Skip already used nodes */
5721 if (test_bit(n, used_nodes))
5724 /* Simple min distance search */
5725 val = node_distance(node, n);
5727 if (val < min_val) {
5733 set_bit(best_node, used_nodes);
5738 * sched_domain_node_span - get a cpumask for a node's sched_domain
5739 * @node: node whose cpumask we're constructing
5740 * @size: number of nodes to include in this span
5742 * Given a node, construct a good cpumask for its sched_domain to span. It
5743 * should be one that prevents unnecessary balancing, but also spreads tasks
5746 static cpumask_t sched_domain_node_span(int node)
5748 DECLARE_BITMAP(used_nodes, MAX_NUMNODES);
5749 cpumask_t span, nodemask;
5753 bitmap_zero(used_nodes, MAX_NUMNODES);
5755 nodemask = node_to_cpumask(node);
5756 cpus_or(span, span, nodemask);
5757 set_bit(node, used_nodes);
5759 for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
5760 int next_node = find_next_best_node(node, used_nodes);
5762 nodemask = node_to_cpumask(next_node);
5763 cpus_or(span, span, nodemask);
5770 int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
5773 * SMT sched-domains:
5775 #ifdef CONFIG_SCHED_SMT
5776 static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
5777 static DEFINE_PER_CPU(struct sched_group, sched_group_cpus);
5779 static int cpu_to_cpu_group(int cpu, const cpumask_t *cpu_map,
5780 struct sched_group **sg)
5783 *sg = &per_cpu(sched_group_cpus, cpu);
5789 * multi-core sched-domains:
5791 #ifdef CONFIG_SCHED_MC
5792 static DEFINE_PER_CPU(struct sched_domain, core_domains);
5793 static DEFINE_PER_CPU(struct sched_group, sched_group_core);
5796 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
5797 static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map,
5798 struct sched_group **sg)
5801 cpumask_t mask = cpu_sibling_map[cpu];
5802 cpus_and(mask, mask, *cpu_map);
5803 group = first_cpu(mask);
5805 *sg = &per_cpu(sched_group_core, group);
5808 #elif defined(CONFIG_SCHED_MC)
5809 static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map,
5810 struct sched_group **sg)
5813 *sg = &per_cpu(sched_group_core, cpu);
5818 static DEFINE_PER_CPU(struct sched_domain, phys_domains);
5819 static DEFINE_PER_CPU(struct sched_group, sched_group_phys);
5821 static int cpu_to_phys_group(int cpu, const cpumask_t *cpu_map,
5822 struct sched_group **sg)
5825 #ifdef CONFIG_SCHED_MC
5826 cpumask_t mask = cpu_coregroup_map(cpu);
5827 cpus_and(mask, mask, *cpu_map);
5828 group = first_cpu(mask);
5829 #elif defined(CONFIG_SCHED_SMT)
5830 cpumask_t mask = cpu_sibling_map[cpu];
5831 cpus_and(mask, mask, *cpu_map);
5832 group = first_cpu(mask);
5837 *sg = &per_cpu(sched_group_phys, group);
5843 * The init_sched_build_groups can't handle what we want to do with node
5844 * groups, so roll our own. Now each node has its own list of groups which
5845 * gets dynamically allocated.
5847 static DEFINE_PER_CPU(struct sched_domain, node_domains);
5848 static struct sched_group **sched_group_nodes_bycpu[NR_CPUS];
5850 static DEFINE_PER_CPU(struct sched_domain, allnodes_domains);
5851 static DEFINE_PER_CPU(struct sched_group, sched_group_allnodes);
5853 static int cpu_to_allnodes_group(int cpu, const cpumask_t *cpu_map,
5854 struct sched_group **sg)
5856 cpumask_t nodemask = node_to_cpumask(cpu_to_node(cpu));
5859 cpus_and(nodemask, nodemask, *cpu_map);
5860 group = first_cpu(nodemask);
5863 *sg = &per_cpu(sched_group_allnodes, group);
5867 static void init_numa_sched_groups_power(struct sched_group *group_head)
5869 struct sched_group *sg = group_head;
5875 for_each_cpu_mask(j, sg->cpumask) {
5876 struct sched_domain *sd;
5878 sd = &per_cpu(phys_domains, j);
5879 if (j != first_cpu(sd->groups->cpumask)) {
5881 * Only add "power" once for each
5887 sg_inc_cpu_power(sg, sd->groups->__cpu_power);
5890 if (sg != group_head)
5896 /* Free memory allocated for various sched_group structures */
5897 static void free_sched_groups(const cpumask_t *cpu_map)
5901 for_each_cpu_mask(cpu, *cpu_map) {
5902 struct sched_group **sched_group_nodes
5903 = sched_group_nodes_bycpu[cpu];
5905 if (!sched_group_nodes)
5908 for (i = 0; i < MAX_NUMNODES; i++) {
5909 cpumask_t nodemask = node_to_cpumask(i);
5910 struct sched_group *oldsg, *sg = sched_group_nodes[i];
5912 cpus_and(nodemask, nodemask, *cpu_map);
5913 if (cpus_empty(nodemask))
5923 if (oldsg != sched_group_nodes[i])
5926 kfree(sched_group_nodes);
5927 sched_group_nodes_bycpu[cpu] = NULL;
5931 static void free_sched_groups(const cpumask_t *cpu_map)
5937 * Initialize sched groups cpu_power.
5939 * cpu_power indicates the capacity of sched group, which is used while
5940 * distributing the load between different sched groups in a sched domain.
5941 * Typically cpu_power for all the groups in a sched domain will be same unless
5942 * there are asymmetries in the topology. If there are asymmetries, group
5943 * having more cpu_power will pickup more load compared to the group having
5946 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
5947 * the maximum number of tasks a group can handle in the presence of other idle
5948 * or lightly loaded groups in the same sched domain.
5950 static void init_sched_groups_power(int cpu, struct sched_domain *sd)
5952 struct sched_domain *child;
5953 struct sched_group *group;
5955 WARN_ON(!sd || !sd->groups);
5957 if (cpu != first_cpu(sd->groups->cpumask))
5962 sd->groups->__cpu_power = 0;
5965 * For perf policy, if the groups in child domain share resources
5966 * (for example cores sharing some portions of the cache hierarchy
5967 * or SMT), then set this domain groups cpu_power such that each group
5968 * can handle only one task, when there are other idle groups in the
5969 * same sched domain.
5971 if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) &&
5973 (SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) {
5974 sg_inc_cpu_power(sd->groups, SCHED_LOAD_SCALE);
5979 * add cpu_power of each child group to this groups cpu_power
5981 group = child->groups;
5983 sg_inc_cpu_power(sd->groups, group->__cpu_power);
5984 group = group->next;
5985 } while (group != child->groups);
5989 * Build sched domains for a given set of cpus and attach the sched domains
5990 * to the individual cpus
5992 static int build_sched_domains(const cpumask_t *cpu_map)
5995 struct sched_domain *sd;
5997 struct sched_group **sched_group_nodes = NULL;
5998 int sd_allnodes = 0;
6001 * Allocate the per-node list of sched groups
6003 sched_group_nodes = kzalloc(sizeof(struct sched_group*)*MAX_NUMNODES,
6005 if (!sched_group_nodes) {
6006 printk(KERN_WARNING "Can not alloc sched group node list\n");
6009 sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes;
6013 * Set up domains for cpus specified by the cpu_map.
6015 for_each_cpu_mask(i, *cpu_map) {
6016 struct sched_domain *sd = NULL, *p;
6017 cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
6019 cpus_and(nodemask, nodemask, *cpu_map);
6022 if (cpus_weight(*cpu_map)
6023 > SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) {
6024 sd = &per_cpu(allnodes_domains, i);
6025 *sd = SD_ALLNODES_INIT;
6026 sd->span = *cpu_map;
6027 cpu_to_allnodes_group(i, cpu_map, &sd->groups);
6033 sd = &per_cpu(node_domains, i);
6035 sd->span = sched_domain_node_span(cpu_to_node(i));
6039 cpus_and(sd->span, sd->span, *cpu_map);
6043 sd = &per_cpu(phys_domains, i);
6045 sd->span = nodemask;
6049 cpu_to_phys_group(i, cpu_map, &sd->groups);
6051 #ifdef CONFIG_SCHED_MC
6053 sd = &per_cpu(core_domains, i);
6055 sd->span = cpu_coregroup_map(i);
6056 cpus_and(sd->span, sd->span, *cpu_map);
6059 cpu_to_core_group(i, cpu_map, &sd->groups);
6062 #ifdef CONFIG_SCHED_SMT
6064 sd = &per_cpu(cpu_domains, i);
6065 *sd = SD_SIBLING_INIT;
6066 sd->span = cpu_sibling_map[i];
6067 cpus_and(sd->span, sd->span, *cpu_map);
6070 cpu_to_cpu_group(i, cpu_map, &sd->groups);
6074 #ifdef CONFIG_SCHED_SMT
6075 /* Set up CPU (sibling) groups */
6076 for_each_cpu_mask(i, *cpu_map) {
6077 cpumask_t this_sibling_map = cpu_sibling_map[i];
6078 cpus_and(this_sibling_map, this_sibling_map, *cpu_map);
6079 if (i != first_cpu(this_sibling_map))
6082 init_sched_build_groups(this_sibling_map, cpu_map, &cpu_to_cpu_group);
6086 #ifdef CONFIG_SCHED_MC
6087 /* Set up multi-core groups */
6088 for_each_cpu_mask(i, *cpu_map) {
6089 cpumask_t this_core_map = cpu_coregroup_map(i);
6090 cpus_and(this_core_map, this_core_map, *cpu_map);
6091 if (i != first_cpu(this_core_map))
6093 init_sched_build_groups(this_core_map, cpu_map, &cpu_to_core_group);
6098 /* Set up physical groups */
6099 for (i = 0; i < MAX_NUMNODES; i++) {
6100 cpumask_t nodemask = node_to_cpumask(i);
6102 cpus_and(nodemask, nodemask, *cpu_map);
6103 if (cpus_empty(nodemask))
6106 init_sched_build_groups(nodemask, cpu_map, &cpu_to_phys_group);
6110 /* Set up node groups */
6112 init_sched_build_groups(*cpu_map, cpu_map, &cpu_to_allnodes_group);
6114 for (i = 0; i < MAX_NUMNODES; i++) {
6115 /* Set up node groups */
6116 struct sched_group *sg, *prev;
6117 cpumask_t nodemask = node_to_cpumask(i);
6118 cpumask_t domainspan;
6119 cpumask_t covered = CPU_MASK_NONE;
6122 cpus_and(nodemask, nodemask, *cpu_map);
6123 if (cpus_empty(nodemask)) {
6124 sched_group_nodes[i] = NULL;
6128 domainspan = sched_domain_node_span(i);
6129 cpus_and(domainspan, domainspan, *cpu_map);
6131 sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i);
6133 printk(KERN_WARNING "Can not alloc domain group for "
6137 sched_group_nodes[i] = sg;
6138 for_each_cpu_mask(j, nodemask) {
6139 struct sched_domain *sd;
6140 sd = &per_cpu(node_domains, j);
6143 sg->__cpu_power = 0;
6144 sg->cpumask = nodemask;
6146 cpus_or(covered, covered, nodemask);
6149 for (j = 0; j < MAX_NUMNODES; j++) {
6150 cpumask_t tmp, notcovered;
6151 int n = (i + j) % MAX_NUMNODES;
6153 cpus_complement(notcovered, covered);
6154 cpus_and(tmp, notcovered, *cpu_map);
6155 cpus_and(tmp, tmp, domainspan);
6156 if (cpus_empty(tmp))
6159 nodemask = node_to_cpumask(n);
6160 cpus_and(tmp, tmp, nodemask);
6161 if (cpus_empty(tmp))
6164 sg = kmalloc_node(sizeof(struct sched_group),
6168 "Can not alloc domain group for node %d\n", j);
6171 sg->__cpu_power = 0;
6173 sg->next = prev->next;
6174 cpus_or(covered, covered, tmp);
6181 /* Calculate CPU power for physical packages and nodes */
6182 #ifdef CONFIG_SCHED_SMT
6183 for_each_cpu_mask(i, *cpu_map) {
6184 sd = &per_cpu(cpu_domains, i);
6185 init_sched_groups_power(i, sd);
6188 #ifdef CONFIG_SCHED_MC
6189 for_each_cpu_mask(i, *cpu_map) {
6190 sd = &per_cpu(core_domains, i);
6191 init_sched_groups_power(i, sd);
6195 for_each_cpu_mask(i, *cpu_map) {
6196 sd = &per_cpu(phys_domains, i);
6197 init_sched_groups_power(i, sd);
6201 for (i = 0; i < MAX_NUMNODES; i++)
6202 init_numa_sched_groups_power(sched_group_nodes[i]);
6205 struct sched_group *sg;
6207 cpu_to_allnodes_group(first_cpu(*cpu_map), cpu_map, &sg);
6208 init_numa_sched_groups_power(sg);
6212 /* Attach the domains */
6213 for_each_cpu_mask(i, *cpu_map) {
6214 struct sched_domain *sd;
6215 #ifdef CONFIG_SCHED_SMT
6216 sd = &per_cpu(cpu_domains, i);
6217 #elif defined(CONFIG_SCHED_MC)
6218 sd = &per_cpu(core_domains, i);
6220 sd = &per_cpu(phys_domains, i);
6222 cpu_attach_domain(sd, i);
6229 free_sched_groups(cpu_map);
6234 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6236 static int arch_init_sched_domains(const cpumask_t *cpu_map)
6238 cpumask_t cpu_default_map;
6242 * Setup mask for cpus without special case scheduling requirements.
6243 * For now this just excludes isolated cpus, but could be used to
6244 * exclude other special cases in the future.
6246 cpus_andnot(cpu_default_map, *cpu_map, cpu_isolated_map);
6248 err = build_sched_domains(&cpu_default_map);
6253 static void arch_destroy_sched_domains(const cpumask_t *cpu_map)
6255 free_sched_groups(cpu_map);
6259 * Detach sched domains from a group of cpus specified in cpu_map
6260 * These cpus will now be attached to the NULL domain
6262 static void detach_destroy_domains(const cpumask_t *cpu_map)
6266 for_each_cpu_mask(i, *cpu_map)
6267 cpu_attach_domain(NULL, i);
6268 synchronize_sched();
6269 arch_destroy_sched_domains(cpu_map);
6273 * Partition sched domains as specified by the cpumasks below.
6274 * This attaches all cpus from the cpumasks to the NULL domain,
6275 * waits for a RCU quiescent period, recalculates sched
6276 * domain information and then attaches them back to the
6277 * correct sched domains
6278 * Call with hotplug lock held
6280 int partition_sched_domains(cpumask_t *partition1, cpumask_t *partition2)
6282 cpumask_t change_map;
6285 cpus_and(*partition1, *partition1, cpu_online_map);
6286 cpus_and(*partition2, *partition2, cpu_online_map);
6287 cpus_or(change_map, *partition1, *partition2);
6289 /* Detach sched domains from all of the affected cpus */
6290 detach_destroy_domains(&change_map);
6291 if (!cpus_empty(*partition1))
6292 err = build_sched_domains(partition1);
6293 if (!err && !cpus_empty(*partition2))
6294 err = build_sched_domains(partition2);
6299 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6300 int arch_reinit_sched_domains(void)
6304 mutex_lock(&sched_hotcpu_mutex);
6305 detach_destroy_domains(&cpu_online_map);
6306 err = arch_init_sched_domains(&cpu_online_map);
6307 mutex_unlock(&sched_hotcpu_mutex);
6312 static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
6316 if (buf[0] != '0' && buf[0] != '1')
6320 sched_smt_power_savings = (buf[0] == '1');
6322 sched_mc_power_savings = (buf[0] == '1');
6324 ret = arch_reinit_sched_domains();
6326 return ret ? ret : count;
6329 int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
6333 #ifdef CONFIG_SCHED_SMT
6335 err = sysfs_create_file(&cls->kset.kobj,
6336 &attr_sched_smt_power_savings.attr);
6338 #ifdef CONFIG_SCHED_MC
6339 if (!err && mc_capable())
6340 err = sysfs_create_file(&cls->kset.kobj,
6341 &attr_sched_mc_power_savings.attr);
6347 #ifdef CONFIG_SCHED_MC
6348 static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page)
6350 return sprintf(page, "%u\n", sched_mc_power_savings);
6352 static ssize_t sched_mc_power_savings_store(struct sys_device *dev,
6353 const char *buf, size_t count)
6355 return sched_power_savings_store(buf, count, 0);
6357 SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
6358 sched_mc_power_savings_store);
6361 #ifdef CONFIG_SCHED_SMT
6362 static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page)
6364 return sprintf(page, "%u\n", sched_smt_power_savings);
6366 static ssize_t sched_smt_power_savings_store(struct sys_device *dev,
6367 const char *buf, size_t count)
6369 return sched_power_savings_store(buf, count, 1);
6371 SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
6372 sched_smt_power_savings_store);
6376 * Force a reinitialization of the sched domains hierarchy. The domains
6377 * and groups cannot be updated in place without racing with the balancing
6378 * code, so we temporarily attach all running cpus to the NULL domain
6379 * which will prevent rebalancing while the sched domains are recalculated.
6381 static int update_sched_domains(struct notifier_block *nfb,
6382 unsigned long action, void *hcpu)
6385 case CPU_UP_PREPARE:
6386 case CPU_UP_PREPARE_FROZEN:
6387 case CPU_DOWN_PREPARE:
6388 case CPU_DOWN_PREPARE_FROZEN:
6389 detach_destroy_domains(&cpu_online_map);
6392 case CPU_UP_CANCELED:
6393 case CPU_UP_CANCELED_FROZEN:
6394 case CPU_DOWN_FAILED:
6395 case CPU_DOWN_FAILED_FROZEN:
6397 case CPU_ONLINE_FROZEN:
6399 case CPU_DEAD_FROZEN:
6401 * Fall through and re-initialise the domains.
6408 /* The hotplug lock is already held by cpu_up/cpu_down */
6409 arch_init_sched_domains(&cpu_online_map);
6414 void __init sched_init_smp(void)
6416 cpumask_t non_isolated_cpus;
6418 mutex_lock(&sched_hotcpu_mutex);
6419 arch_init_sched_domains(&cpu_online_map);
6420 cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
6421 if (cpus_empty(non_isolated_cpus))
6422 cpu_set(smp_processor_id(), non_isolated_cpus);
6423 mutex_unlock(&sched_hotcpu_mutex);
6424 /* XXX: Theoretical race here - CPU may be hotplugged now */
6425 hotcpu_notifier(update_sched_domains, 0);
6427 /* Move init over to a non-isolated CPU */
6428 if (set_cpus_allowed(current, non_isolated_cpus) < 0)
6432 void __init sched_init_smp(void)
6435 #endif /* CONFIG_SMP */
6437 int in_sched_functions(unsigned long addr)
6439 /* Linker adds these: start and end of __sched functions */
6440 extern char __sched_text_start[], __sched_text_end[];
6442 return in_lock_functions(addr) ||
6443 (addr >= (unsigned long)__sched_text_start
6444 && addr < (unsigned long)__sched_text_end);
6447 void __init sched_init(void)
6450 int highest_cpu = 0;
6452 for_each_possible_cpu(i) {
6453 struct prio_array *array;
6457 spin_lock_init(&rq->lock);
6458 lockdep_set_class(&rq->lock, &rq->rq_lock_key);
6460 rq->active = rq->arrays;
6461 rq->expired = rq->arrays + 1;
6462 rq->best_expired_prio = MAX_PRIO;
6466 for (j = 1; j < 3; j++)
6467 rq->cpu_load[j] = 0;
6468 rq->active_balance = 0;
6471 rq->migration_thread = NULL;
6472 INIT_LIST_HEAD(&rq->migration_queue);
6474 atomic_set(&rq->nr_iowait, 0);
6476 for (j = 0; j < 2; j++) {
6477 array = rq->arrays + j;
6478 for (k = 0; k < MAX_PRIO; k++) {
6479 INIT_LIST_HEAD(array->queue + k);
6480 __clear_bit(k, array->bitmap);
6482 // delimiter for bitsearch
6483 __set_bit(MAX_PRIO, array->bitmap);
6488 set_load_weight(&init_task);
6491 nr_cpu_ids = highest_cpu + 1;
6492 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL);
6495 #ifdef CONFIG_RT_MUTEXES
6496 plist_head_init(&init_task.pi_waiters, &init_task.pi_lock);
6500 * The boot idle thread does lazy MMU switching as well:
6502 atomic_inc(&init_mm.mm_count);
6503 enter_lazy_tlb(&init_mm, current);
6506 * Make us the idle thread. Technically, schedule() should not be
6507 * called from this thread, however somewhere below it might be,
6508 * but because we are the idle thread, we just pick up running again
6509 * when this runqueue becomes "idle".
6511 init_idle(current, smp_processor_id());
6514 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6515 void __might_sleep(char *file, int line)
6518 static unsigned long prev_jiffy; /* ratelimiting */
6520 if ((in_atomic() || irqs_disabled()) &&
6521 system_state == SYSTEM_RUNNING && !oops_in_progress) {
6522 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
6524 prev_jiffy = jiffies;
6525 printk(KERN_ERR "BUG: sleeping function called from invalid"
6526 " context at %s:%d\n", file, line);
6527 printk("in_atomic():%d, irqs_disabled():%d\n",
6528 in_atomic(), irqs_disabled());
6529 debug_show_held_locks(current);
6530 if (irqs_disabled())
6531 print_irqtrace_events(current);
6536 EXPORT_SYMBOL(__might_sleep);
6539 #ifdef CONFIG_MAGIC_SYSRQ
6540 void normalize_rt_tasks(void)
6542 struct prio_array *array;
6543 struct task_struct *g, *p;
6544 unsigned long flags;
6547 read_lock_irq(&tasklist_lock);
6549 do_each_thread(g, p) {
6553 spin_lock_irqsave(&p->pi_lock, flags);
6554 rq = __task_rq_lock(p);
6558 deactivate_task(p, task_rq(p));
6559 __setscheduler(p, SCHED_NORMAL, 0);
6561 __activate_task(p, task_rq(p));
6562 resched_task(rq->curr);
6565 __task_rq_unlock(rq);
6566 spin_unlock_irqrestore(&p->pi_lock, flags);
6567 } while_each_thread(g, p);
6569 read_unlock_irq(&tasklist_lock);
6572 #endif /* CONFIG_MAGIC_SYSRQ */
6576 * These functions are only useful for the IA64 MCA handling.
6578 * They can only be called when the whole system has been
6579 * stopped - every CPU needs to be quiescent, and no scheduling
6580 * activity can take place. Using them for anything else would
6581 * be a serious bug, and as a result, they aren't even visible
6582 * under any other configuration.
6586 * curr_task - return the current task for a given cpu.
6587 * @cpu: the processor in question.
6589 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6591 struct task_struct *curr_task(int cpu)
6593 return cpu_curr(cpu);
6597 * set_curr_task - set the current task for a given cpu.
6598 * @cpu: the processor in question.
6599 * @p: the task pointer to set.
6601 * Description: This function must only be used when non-maskable interrupts
6602 * are serviced on a separate stack. It allows the architecture to switch the
6603 * notion of the current task on a cpu in a non-blocking manner. This function
6604 * must be called with all CPU's synchronized, and interrupts disabled, the
6605 * and caller must save the original value of the current task (see
6606 * curr_task() above) and restore that value before reenabling interrupts and
6607 * re-starting the system.
6609 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6611 void set_curr_task(int cpu, struct task_struct *p)