4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
30 #include <linux/module.h>
31 #include <linux/nmi.h>
32 #include <linux/init.h>
33 #include <linux/uaccess.h>
34 #include <linux/highmem.h>
35 #include <asm/mmu_context.h>
36 #include <linux/interrupt.h>
37 #include <linux/capability.h>
38 #include <linux/completion.h>
39 #include <linux/kernel_stat.h>
40 #include <linux/debug_locks.h>
41 #include <linux/perf_event.h>
42 #include <linux/security.h>
43 #include <linux/notifier.h>
44 #include <linux/profile.h>
45 #include <linux/freezer.h>
46 #include <linux/vmalloc.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/smp.h>
51 #include <linux/threads.h>
52 #include <linux/timer.h>
53 #include <linux/rcupdate.h>
54 #include <linux/cpu.h>
55 #include <linux/cpuset.h>
56 #include <linux/percpu.h>
57 #include <linux/proc_fs.h>
58 #include <linux/seq_file.h>
59 #include <linux/stop_machine.h>
60 #include <linux/sysctl.h>
61 #include <linux/syscalls.h>
62 #include <linux/times.h>
63 #include <linux/tsacct_kern.h>
64 #include <linux/kprobes.h>
65 #include <linux/delayacct.h>
66 #include <linux/unistd.h>
67 #include <linux/pagemap.h>
68 #include <linux/hrtimer.h>
69 #include <linux/tick.h>
70 #include <linux/debugfs.h>
71 #include <linux/ctype.h>
72 #include <linux/ftrace.h>
73 #include <linux/slab.h>
76 #include <asm/irq_regs.h>
77 #include <asm/mutex.h>
78 #ifdef CONFIG_PARAVIRT
79 #include <asm/paravirt.h>
82 #include "sched_cpupri.h"
83 #include "workqueue_sched.h"
84 #include "sched_autogroup.h"
86 #define CREATE_TRACE_POINTS
87 #include <trace/events/sched.h>
90 * Convert user-nice values [ -20 ... 0 ... 19 ]
91 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
94 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
95 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
96 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
99 * 'User priority' is the nice value converted to something we
100 * can work with better when scaling various scheduler parameters,
101 * it's a [ 0 ... 39 ] range.
103 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
104 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
105 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
108 * Helpers for converting nanosecond timing to jiffy resolution
110 #define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
112 #define NICE_0_LOAD SCHED_LOAD_SCALE
113 #define NICE_0_SHIFT SCHED_LOAD_SHIFT
116 * These are the 'tuning knobs' of the scheduler:
118 * default timeslice is 100 msecs (used only for SCHED_RR tasks).
119 * Timeslices get refilled after they expire.
121 #define DEF_TIMESLICE (100 * HZ / 1000)
124 * single value that denotes runtime == period, ie unlimited time.
126 #define RUNTIME_INF ((u64)~0ULL)
128 static inline int rt_policy(int policy
)
130 if (policy
== SCHED_FIFO
|| policy
== SCHED_RR
)
135 static inline int task_has_rt_policy(struct task_struct
*p
)
137 return rt_policy(p
->policy
);
141 * This is the priority-queue data structure of the RT scheduling class:
143 struct rt_prio_array
{
144 DECLARE_BITMAP(bitmap
, MAX_RT_PRIO
+1); /* include 1 bit for delimiter */
145 struct list_head queue
[MAX_RT_PRIO
];
148 struct rt_bandwidth
{
149 /* nests inside the rq lock: */
150 raw_spinlock_t rt_runtime_lock
;
153 struct hrtimer rt_period_timer
;
156 static struct rt_bandwidth def_rt_bandwidth
;
158 static int do_sched_rt_period_timer(struct rt_bandwidth
*rt_b
, int overrun
);
160 static enum hrtimer_restart
sched_rt_period_timer(struct hrtimer
*timer
)
162 struct rt_bandwidth
*rt_b
=
163 container_of(timer
, struct rt_bandwidth
, rt_period_timer
);
169 now
= hrtimer_cb_get_time(timer
);
170 overrun
= hrtimer_forward(timer
, now
, rt_b
->rt_period
);
175 idle
= do_sched_rt_period_timer(rt_b
, overrun
);
178 return idle
? HRTIMER_NORESTART
: HRTIMER_RESTART
;
182 void init_rt_bandwidth(struct rt_bandwidth
*rt_b
, u64 period
, u64 runtime
)
184 rt_b
->rt_period
= ns_to_ktime(period
);
185 rt_b
->rt_runtime
= runtime
;
187 raw_spin_lock_init(&rt_b
->rt_runtime_lock
);
189 hrtimer_init(&rt_b
->rt_period_timer
,
190 CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
191 rt_b
->rt_period_timer
.function
= sched_rt_period_timer
;
194 static inline int rt_bandwidth_enabled(void)
196 return sysctl_sched_rt_runtime
>= 0;
199 static void start_rt_bandwidth(struct rt_bandwidth
*rt_b
)
203 if (!rt_bandwidth_enabled() || rt_b
->rt_runtime
== RUNTIME_INF
)
206 if (hrtimer_active(&rt_b
->rt_period_timer
))
209 raw_spin_lock(&rt_b
->rt_runtime_lock
);
214 if (hrtimer_active(&rt_b
->rt_period_timer
))
217 now
= hrtimer_cb_get_time(&rt_b
->rt_period_timer
);
218 hrtimer_forward(&rt_b
->rt_period_timer
, now
, rt_b
->rt_period
);
220 soft
= hrtimer_get_softexpires(&rt_b
->rt_period_timer
);
221 hard
= hrtimer_get_expires(&rt_b
->rt_period_timer
);
222 delta
= ktime_to_ns(ktime_sub(hard
, soft
));
223 __hrtimer_start_range_ns(&rt_b
->rt_period_timer
, soft
, delta
,
224 HRTIMER_MODE_ABS_PINNED
, 0);
226 raw_spin_unlock(&rt_b
->rt_runtime_lock
);
229 #ifdef CONFIG_RT_GROUP_SCHED
230 static void destroy_rt_bandwidth(struct rt_bandwidth
*rt_b
)
232 hrtimer_cancel(&rt_b
->rt_period_timer
);
237 * sched_domains_mutex serializes calls to init_sched_domains,
238 * detach_destroy_domains and partition_sched_domains.
240 static DEFINE_MUTEX(sched_domains_mutex
);
242 #ifdef CONFIG_CGROUP_SCHED
244 #include <linux/cgroup.h>
248 static LIST_HEAD(task_groups
);
250 /* task group related information */
252 struct cgroup_subsys_state css
;
254 #ifdef CONFIG_FAIR_GROUP_SCHED
255 /* schedulable entities of this group on each cpu */
256 struct sched_entity
**se
;
257 /* runqueue "owned" by this group on each cpu */
258 struct cfs_rq
**cfs_rq
;
259 unsigned long shares
;
261 atomic_t load_weight
;
264 #ifdef CONFIG_RT_GROUP_SCHED
265 struct sched_rt_entity
**rt_se
;
266 struct rt_rq
**rt_rq
;
268 struct rt_bandwidth rt_bandwidth
;
272 struct list_head list
;
274 struct task_group
*parent
;
275 struct list_head siblings
;
276 struct list_head children
;
278 #ifdef CONFIG_SCHED_AUTOGROUP
279 struct autogroup
*autogroup
;
283 /* task_group_lock serializes the addition/removal of task groups */
284 static DEFINE_SPINLOCK(task_group_lock
);
286 #ifdef CONFIG_FAIR_GROUP_SCHED
288 # define ROOT_TASK_GROUP_LOAD NICE_0_LOAD
291 * A weight of 0 or 1 can cause arithmetics problems.
292 * A weight of a cfs_rq is the sum of weights of which entities
293 * are queued on this cfs_rq, so a weight of a entity should not be
294 * too large, so as the shares value of a task group.
295 * (The default weight is 1024 - so there's no practical
296 * limitation from this.)
298 #define MIN_SHARES (1UL << 1)
299 #define MAX_SHARES (1UL << 18)
301 static int root_task_group_load
= ROOT_TASK_GROUP_LOAD
;
304 /* Default task group.
305 * Every task in system belong to this group at bootup.
307 struct task_group root_task_group
;
309 #endif /* CONFIG_CGROUP_SCHED */
311 /* CFS-related fields in a runqueue */
313 struct load_weight load
;
314 unsigned long nr_running
, h_nr_running
;
319 u64 min_vruntime_copy
;
322 struct rb_root tasks_timeline
;
323 struct rb_node
*rb_leftmost
;
325 struct list_head tasks
;
326 struct list_head
*balance_iterator
;
329 * 'curr' points to currently running entity on this cfs_rq.
330 * It is set to NULL otherwise (i.e when none are currently running).
332 struct sched_entity
*curr
, *next
, *last
, *skip
;
334 #ifdef CONFIG_SCHED_DEBUG
335 unsigned int nr_spread_over
;
338 #ifdef CONFIG_FAIR_GROUP_SCHED
339 struct rq
*rq
; /* cpu runqueue to which this cfs_rq is attached */
342 * leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
343 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
344 * (like users, containers etc.)
346 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
347 * list is used during load balance.
350 struct list_head leaf_cfs_rq_list
;
351 struct task_group
*tg
; /* group that "owns" this runqueue */
355 * the part of load.weight contributed by tasks
357 unsigned long task_weight
;
360 * h_load = weight * f(tg)
362 * Where f(tg) is the recursive weight fraction assigned to
365 unsigned long h_load
;
368 * Maintaining per-cpu shares distribution for group scheduling
370 * load_stamp is the last time we updated the load average
371 * load_last is the last time we updated the load average and saw load
372 * load_unacc_exec_time is currently unaccounted execution time
376 u64 load_stamp
, load_last
, load_unacc_exec_time
;
378 unsigned long load_contribution
;
383 /* Real-Time classes' related field in a runqueue: */
385 struct rt_prio_array active
;
386 unsigned long rt_nr_running
;
387 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
389 int curr
; /* highest queued rt task prio */
391 int next
; /* next highest */
396 unsigned long rt_nr_migratory
;
397 unsigned long rt_nr_total
;
399 struct plist_head pushable_tasks
;
404 /* Nests inside the rq lock: */
405 raw_spinlock_t rt_runtime_lock
;
407 #ifdef CONFIG_RT_GROUP_SCHED
408 unsigned long rt_nr_boosted
;
411 struct list_head leaf_rt_rq_list
;
412 struct task_group
*tg
;
419 * We add the notion of a root-domain which will be used to define per-domain
420 * variables. Each exclusive cpuset essentially defines an island domain by
421 * fully partitioning the member cpus from any other cpuset. Whenever a new
422 * exclusive cpuset is created, we also create and attach a new root-domain
431 cpumask_var_t online
;
434 * The "RT overload" flag: it gets set if a CPU has more than
435 * one runnable RT task.
437 cpumask_var_t rto_mask
;
438 struct cpupri cpupri
;
442 * By default the system creates a single root-domain with all cpus as
443 * members (mimicking the global state we have today).
445 static struct root_domain def_root_domain
;
447 #endif /* CONFIG_SMP */
450 * This is the main, per-CPU runqueue data structure.
452 * Locking rule: those places that want to lock multiple runqueues
453 * (such as the load balancing or the thread migration code), lock
454 * acquire operations must be ordered by ascending &runqueue.
461 * nr_running and cpu_load should be in the same cacheline because
462 * remote CPUs use both these fields when doing load calculation.
464 unsigned long nr_running
;
465 #define CPU_LOAD_IDX_MAX 5
466 unsigned long cpu_load
[CPU_LOAD_IDX_MAX
];
467 unsigned long last_load_update_tick
;
470 unsigned char nohz_balance_kick
;
472 int skip_clock_update
;
474 /* capture load from *all* tasks on this cpu: */
475 struct load_weight load
;
476 unsigned long nr_load_updates
;
482 #ifdef CONFIG_FAIR_GROUP_SCHED
483 /* list of leaf cfs_rq on this cpu: */
484 struct list_head leaf_cfs_rq_list
;
486 #ifdef CONFIG_RT_GROUP_SCHED
487 struct list_head leaf_rt_rq_list
;
491 * This is part of a global counter where only the total sum
492 * over all CPUs matters. A task can increase this counter on
493 * one CPU and if it got migrated afterwards it may decrease
494 * it on another CPU. Always updated under the runqueue lock:
496 unsigned long nr_uninterruptible
;
498 struct task_struct
*curr
, *idle
, *stop
;
499 unsigned long next_balance
;
500 struct mm_struct
*prev_mm
;
508 struct root_domain
*rd
;
509 struct sched_domain
*sd
;
511 unsigned long cpu_power
;
513 unsigned char idle_at_tick
;
514 /* For active balancing */
518 struct cpu_stop_work active_balance_work
;
519 /* cpu of this runqueue: */
529 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
532 #ifdef CONFIG_PARAVIRT
535 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
536 u64 prev_steal_time_rq
;
539 /* calc_load related fields */
540 unsigned long calc_load_update
;
541 long calc_load_active
;
543 #ifdef CONFIG_SCHED_HRTICK
545 int hrtick_csd_pending
;
546 struct call_single_data hrtick_csd
;
548 struct hrtimer hrtick_timer
;
551 #ifdef CONFIG_SCHEDSTATS
553 struct sched_info rq_sched_info
;
554 unsigned long long rq_cpu_time
;
555 /* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
557 /* sys_sched_yield() stats */
558 unsigned int yld_count
;
560 /* schedule() stats */
561 unsigned int sched_switch
;
562 unsigned int sched_count
;
563 unsigned int sched_goidle
;
565 /* try_to_wake_up() stats */
566 unsigned int ttwu_count
;
567 unsigned int ttwu_local
;
571 struct task_struct
*wake_list
;
575 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
578 static void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
, int flags
);
580 static inline int cpu_of(struct rq
*rq
)
589 #define rcu_dereference_check_sched_domain(p) \
590 rcu_dereference_check((p), \
591 lockdep_is_held(&sched_domains_mutex))
594 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
595 * See detach_destroy_domains: synchronize_sched for details.
597 * The domain tree of any CPU may only be accessed from within
598 * preempt-disabled sections.
600 #define for_each_domain(cpu, __sd) \
601 for (__sd = rcu_dereference_check_sched_domain(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
603 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
604 #define this_rq() (&__get_cpu_var(runqueues))
605 #define task_rq(p) cpu_rq(task_cpu(p))
606 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
607 #define raw_rq() (&__raw_get_cpu_var(runqueues))
609 #ifdef CONFIG_CGROUP_SCHED
612 * Return the group to which this tasks belongs.
614 * We use task_subsys_state_check() and extend the RCU verification with
615 * pi->lock and rq->lock because cpu_cgroup_attach() holds those locks for each
616 * task it moves into the cgroup. Therefore by holding either of those locks,
617 * we pin the task to the current cgroup.
619 static inline struct task_group
*task_group(struct task_struct
*p
)
621 struct task_group
*tg
;
622 struct cgroup_subsys_state
*css
;
624 css
= task_subsys_state_check(p
, cpu_cgroup_subsys_id
,
625 lockdep_is_held(&p
->pi_lock
) ||
626 lockdep_is_held(&task_rq(p
)->lock
));
627 tg
= container_of(css
, struct task_group
, css
);
629 return autogroup_task_group(p
, tg
);
632 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
633 static inline void set_task_rq(struct task_struct
*p
, unsigned int cpu
)
635 #ifdef CONFIG_FAIR_GROUP_SCHED
636 p
->se
.cfs_rq
= task_group(p
)->cfs_rq
[cpu
];
637 p
->se
.parent
= task_group(p
)->se
[cpu
];
640 #ifdef CONFIG_RT_GROUP_SCHED
641 p
->rt
.rt_rq
= task_group(p
)->rt_rq
[cpu
];
642 p
->rt
.parent
= task_group(p
)->rt_se
[cpu
];
646 #else /* CONFIG_CGROUP_SCHED */
648 static inline void set_task_rq(struct task_struct
*p
, unsigned int cpu
) { }
649 static inline struct task_group
*task_group(struct task_struct
*p
)
654 #endif /* CONFIG_CGROUP_SCHED */
656 static void update_rq_clock_task(struct rq
*rq
, s64 delta
);
658 static void update_rq_clock(struct rq
*rq
)
662 if (rq
->skip_clock_update
> 0)
665 delta
= sched_clock_cpu(cpu_of(rq
)) - rq
->clock
;
667 update_rq_clock_task(rq
, delta
);
671 * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
673 #ifdef CONFIG_SCHED_DEBUG
674 # define const_debug __read_mostly
676 # define const_debug static const
680 * runqueue_is_locked - Returns true if the current cpu runqueue is locked
681 * @cpu: the processor in question.
683 * This interface allows printk to be called with the runqueue lock
684 * held and know whether or not it is OK to wake up the klogd.
686 int runqueue_is_locked(int cpu
)
688 return raw_spin_is_locked(&cpu_rq(cpu
)->lock
);
692 * Debugging: various feature bits
695 #define SCHED_FEAT(name, enabled) \
696 __SCHED_FEAT_##name ,
699 #include "sched_features.h"
704 #define SCHED_FEAT(name, enabled) \
705 (1UL << __SCHED_FEAT_##name) * enabled |
707 const_debug
unsigned int sysctl_sched_features
=
708 #include "sched_features.h"
713 #ifdef CONFIG_SCHED_DEBUG
714 #define SCHED_FEAT(name, enabled) \
717 static __read_mostly
char *sched_feat_names
[] = {
718 #include "sched_features.h"
724 static int sched_feat_show(struct seq_file
*m
, void *v
)
728 for (i
= 0; sched_feat_names
[i
]; i
++) {
729 if (!(sysctl_sched_features
& (1UL << i
)))
731 seq_printf(m
, "%s ", sched_feat_names
[i
]);
739 sched_feat_write(struct file
*filp
, const char __user
*ubuf
,
740 size_t cnt
, loff_t
*ppos
)
750 if (copy_from_user(&buf
, ubuf
, cnt
))
756 if (strncmp(cmp
, "NO_", 3) == 0) {
761 for (i
= 0; sched_feat_names
[i
]; i
++) {
762 if (strcmp(cmp
, sched_feat_names
[i
]) == 0) {
764 sysctl_sched_features
&= ~(1UL << i
);
766 sysctl_sched_features
|= (1UL << i
);
771 if (!sched_feat_names
[i
])
779 static int sched_feat_open(struct inode
*inode
, struct file
*filp
)
781 return single_open(filp
, sched_feat_show
, NULL
);
784 static const struct file_operations sched_feat_fops
= {
785 .open
= sched_feat_open
,
786 .write
= sched_feat_write
,
789 .release
= single_release
,
792 static __init
int sched_init_debug(void)
794 debugfs_create_file("sched_features", 0644, NULL
, NULL
,
799 late_initcall(sched_init_debug
);
803 #define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
806 * Number of tasks to iterate in a single balance run.
807 * Limited because this is done with IRQs disabled.
809 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
812 * period over which we average the RT time consumption, measured
817 const_debug
unsigned int sysctl_sched_time_avg
= MSEC_PER_SEC
;
820 * period over which we measure -rt task cpu usage in us.
823 unsigned int sysctl_sched_rt_period
= 1000000;
825 static __read_mostly
int scheduler_running
;
828 * part of the period that we allow rt tasks to run in us.
831 int sysctl_sched_rt_runtime
= 950000;
833 static inline u64
global_rt_period(void)
835 return (u64
)sysctl_sched_rt_period
* NSEC_PER_USEC
;
838 static inline u64
global_rt_runtime(void)
840 if (sysctl_sched_rt_runtime
< 0)
843 return (u64
)sysctl_sched_rt_runtime
* NSEC_PER_USEC
;
846 #ifndef prepare_arch_switch
847 # define prepare_arch_switch(next) do { } while (0)
849 #ifndef finish_arch_switch
850 # define finish_arch_switch(prev) do { } while (0)
853 static inline int task_current(struct rq
*rq
, struct task_struct
*p
)
855 return rq
->curr
== p
;
858 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
863 return task_current(rq
, p
);
867 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
868 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
872 * We can optimise this out completely for !SMP, because the
873 * SMP rebalancing from interrupt is the only thing that cares
880 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
884 * After ->on_cpu is cleared, the task can be moved to a different CPU.
885 * We must ensure this doesn't happen until the switch is completely
891 #ifdef CONFIG_DEBUG_SPINLOCK
892 /* this is a valid case when another task releases the spinlock */
893 rq
->lock
.owner
= current
;
896 * If we are tracking spinlock dependencies then we have to
897 * fix up the runqueue lock - which gets 'carried over' from
900 spin_acquire(&rq
->lock
.dep_map
, 0, 0, _THIS_IP_
);
902 raw_spin_unlock_irq(&rq
->lock
);
905 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
906 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
910 * We can optimise this out completely for !SMP, because the
911 * SMP rebalancing from interrupt is the only thing that cares
916 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
917 raw_spin_unlock_irq(&rq
->lock
);
919 raw_spin_unlock(&rq
->lock
);
923 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
927 * After ->on_cpu is cleared, the task can be moved to a different CPU.
928 * We must ensure this doesn't happen until the switch is completely
934 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
938 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
941 * __task_rq_lock - lock the rq @p resides on.
943 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
948 lockdep_assert_held(&p
->pi_lock
);
952 raw_spin_lock(&rq
->lock
);
953 if (likely(rq
== task_rq(p
)))
955 raw_spin_unlock(&rq
->lock
);
960 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
962 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
963 __acquires(p
->pi_lock
)
969 raw_spin_lock_irqsave(&p
->pi_lock
, *flags
);
971 raw_spin_lock(&rq
->lock
);
972 if (likely(rq
== task_rq(p
)))
974 raw_spin_unlock(&rq
->lock
);
975 raw_spin_unlock_irqrestore(&p
->pi_lock
, *flags
);
979 static void __task_rq_unlock(struct rq
*rq
)
982 raw_spin_unlock(&rq
->lock
);
986 task_rq_unlock(struct rq
*rq
, struct task_struct
*p
, unsigned long *flags
)
988 __releases(p
->pi_lock
)
990 raw_spin_unlock(&rq
->lock
);
991 raw_spin_unlock_irqrestore(&p
->pi_lock
, *flags
);
995 * this_rq_lock - lock this runqueue and disable interrupts.
997 static struct rq
*this_rq_lock(void)
1002 local_irq_disable();
1004 raw_spin_lock(&rq
->lock
);
1009 #ifdef CONFIG_SCHED_HRTICK
1011 * Use HR-timers to deliver accurate preemption points.
1013 * Its all a bit involved since we cannot program an hrt while holding the
1014 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
1017 * When we get rescheduled we reprogram the hrtick_timer outside of the
1023 * - enabled by features
1024 * - hrtimer is actually high res
1026 static inline int hrtick_enabled(struct rq
*rq
)
1028 if (!sched_feat(HRTICK
))
1030 if (!cpu_active(cpu_of(rq
)))
1032 return hrtimer_is_hres_active(&rq
->hrtick_timer
);
1035 static void hrtick_clear(struct rq
*rq
)
1037 if (hrtimer_active(&rq
->hrtick_timer
))
1038 hrtimer_cancel(&rq
->hrtick_timer
);
1042 * High-resolution timer tick.
1043 * Runs from hardirq context with interrupts disabled.
1045 static enum hrtimer_restart
hrtick(struct hrtimer
*timer
)
1047 struct rq
*rq
= container_of(timer
, struct rq
, hrtick_timer
);
1049 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
1051 raw_spin_lock(&rq
->lock
);
1052 update_rq_clock(rq
);
1053 rq
->curr
->sched_class
->task_tick(rq
, rq
->curr
, 1);
1054 raw_spin_unlock(&rq
->lock
);
1056 return HRTIMER_NORESTART
;
1061 * called from hardirq (IPI) context
1063 static void __hrtick_start(void *arg
)
1065 struct rq
*rq
= arg
;
1067 raw_spin_lock(&rq
->lock
);
1068 hrtimer_restart(&rq
->hrtick_timer
);
1069 rq
->hrtick_csd_pending
= 0;
1070 raw_spin_unlock(&rq
->lock
);
1074 * Called to set the hrtick timer state.
1076 * called with rq->lock held and irqs disabled
1078 static void hrtick_start(struct rq
*rq
, u64 delay
)
1080 struct hrtimer
*timer
= &rq
->hrtick_timer
;
1081 ktime_t time
= ktime_add_ns(timer
->base
->get_time(), delay
);
1083 hrtimer_set_expires(timer
, time
);
1085 if (rq
== this_rq()) {
1086 hrtimer_restart(timer
);
1087 } else if (!rq
->hrtick_csd_pending
) {
1088 __smp_call_function_single(cpu_of(rq
), &rq
->hrtick_csd
, 0);
1089 rq
->hrtick_csd_pending
= 1;
1094 hotplug_hrtick(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
1096 int cpu
= (int)(long)hcpu
;
1099 case CPU_UP_CANCELED
:
1100 case CPU_UP_CANCELED_FROZEN
:
1101 case CPU_DOWN_PREPARE
:
1102 case CPU_DOWN_PREPARE_FROZEN
:
1104 case CPU_DEAD_FROZEN
:
1105 hrtick_clear(cpu_rq(cpu
));
1112 static __init
void init_hrtick(void)
1114 hotcpu_notifier(hotplug_hrtick
, 0);
1118 * Called to set the hrtick timer state.
1120 * called with rq->lock held and irqs disabled
1122 static void hrtick_start(struct rq
*rq
, u64 delay
)
1124 __hrtimer_start_range_ns(&rq
->hrtick_timer
, ns_to_ktime(delay
), 0,
1125 HRTIMER_MODE_REL_PINNED
, 0);
1128 static inline void init_hrtick(void)
1131 #endif /* CONFIG_SMP */
1133 static void init_rq_hrtick(struct rq
*rq
)
1136 rq
->hrtick_csd_pending
= 0;
1138 rq
->hrtick_csd
.flags
= 0;
1139 rq
->hrtick_csd
.func
= __hrtick_start
;
1140 rq
->hrtick_csd
.info
= rq
;
1143 hrtimer_init(&rq
->hrtick_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1144 rq
->hrtick_timer
.function
= hrtick
;
1146 #else /* CONFIG_SCHED_HRTICK */
1147 static inline void hrtick_clear(struct rq
*rq
)
1151 static inline void init_rq_hrtick(struct rq
*rq
)
1155 static inline void init_hrtick(void)
1158 #endif /* CONFIG_SCHED_HRTICK */
1161 * resched_task - mark a task 'to be rescheduled now'.
1163 * On UP this means the setting of the need_resched flag, on SMP it
1164 * might also involve a cross-CPU call to trigger the scheduler on
1169 #ifndef tsk_is_polling
1170 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1173 static void resched_task(struct task_struct
*p
)
1177 assert_raw_spin_locked(&task_rq(p
)->lock
);
1179 if (test_tsk_need_resched(p
))
1182 set_tsk_need_resched(p
);
1185 if (cpu
== smp_processor_id())
1188 /* NEED_RESCHED must be visible before we test polling */
1190 if (!tsk_is_polling(p
))
1191 smp_send_reschedule(cpu
);
1194 static void resched_cpu(int cpu
)
1196 struct rq
*rq
= cpu_rq(cpu
);
1197 unsigned long flags
;
1199 if (!raw_spin_trylock_irqsave(&rq
->lock
, flags
))
1201 resched_task(cpu_curr(cpu
));
1202 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1207 * In the semi idle case, use the nearest busy cpu for migrating timers
1208 * from an idle cpu. This is good for power-savings.
1210 * We don't do similar optimization for completely idle system, as
1211 * selecting an idle cpu will add more delays to the timers than intended
1212 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
1214 int get_nohz_timer_target(void)
1216 int cpu
= smp_processor_id();
1218 struct sched_domain
*sd
;
1221 for_each_domain(cpu
, sd
) {
1222 for_each_cpu(i
, sched_domain_span(sd
)) {
1234 * When add_timer_on() enqueues a timer into the timer wheel of an
1235 * idle CPU then this timer might expire before the next timer event
1236 * which is scheduled to wake up that CPU. In case of a completely
1237 * idle system the next event might even be infinite time into the
1238 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
1239 * leaves the inner idle loop so the newly added timer is taken into
1240 * account when the CPU goes back to idle and evaluates the timer
1241 * wheel for the next timer event.
1243 void wake_up_idle_cpu(int cpu
)
1245 struct rq
*rq
= cpu_rq(cpu
);
1247 if (cpu
== smp_processor_id())
1251 * This is safe, as this function is called with the timer
1252 * wheel base lock of (cpu) held. When the CPU is on the way
1253 * to idle and has not yet set rq->curr to idle then it will
1254 * be serialized on the timer wheel base lock and take the new
1255 * timer into account automatically.
1257 if (rq
->curr
!= rq
->idle
)
1261 * We can set TIF_RESCHED on the idle task of the other CPU
1262 * lockless. The worst case is that the other CPU runs the
1263 * idle task through an additional NOOP schedule()
1265 set_tsk_need_resched(rq
->idle
);
1267 /* NEED_RESCHED must be visible before we test polling */
1269 if (!tsk_is_polling(rq
->idle
))
1270 smp_send_reschedule(cpu
);
1273 #endif /* CONFIG_NO_HZ */
1275 static u64
sched_avg_period(void)
1277 return (u64
)sysctl_sched_time_avg
* NSEC_PER_MSEC
/ 2;
1280 static void sched_avg_update(struct rq
*rq
)
1282 s64 period
= sched_avg_period();
1284 while ((s64
)(rq
->clock
- rq
->age_stamp
) > period
) {
1286 * Inline assembly required to prevent the compiler
1287 * optimising this loop into a divmod call.
1288 * See __iter_div_u64_rem() for another example of this.
1290 asm("" : "+rm" (rq
->age_stamp
));
1291 rq
->age_stamp
+= period
;
1296 static void sched_rt_avg_update(struct rq
*rq
, u64 rt_delta
)
1298 rq
->rt_avg
+= rt_delta
;
1299 sched_avg_update(rq
);
1302 #else /* !CONFIG_SMP */
1303 static void resched_task(struct task_struct
*p
)
1305 assert_raw_spin_locked(&task_rq(p
)->lock
);
1306 set_tsk_need_resched(p
);
1309 static void sched_rt_avg_update(struct rq
*rq
, u64 rt_delta
)
1313 static void sched_avg_update(struct rq
*rq
)
1316 #endif /* CONFIG_SMP */
1318 #if BITS_PER_LONG == 32
1319 # define WMULT_CONST (~0UL)
1321 # define WMULT_CONST (1UL << 32)
1324 #define WMULT_SHIFT 32
1327 * Shift right and round:
1329 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
1332 * delta *= weight / lw
1334 static unsigned long
1335 calc_delta_mine(unsigned long delta_exec
, unsigned long weight
,
1336 struct load_weight
*lw
)
1341 * weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched
1342 * entities since MIN_SHARES = 2. Treat weight as 1 if less than
1343 * 2^SCHED_LOAD_RESOLUTION.
1345 if (likely(weight
> (1UL << SCHED_LOAD_RESOLUTION
)))
1346 tmp
= (u64
)delta_exec
* scale_load_down(weight
);
1348 tmp
= (u64
)delta_exec
;
1350 if (!lw
->inv_weight
) {
1351 unsigned long w
= scale_load_down(lw
->weight
);
1353 if (BITS_PER_LONG
> 32 && unlikely(w
>= WMULT_CONST
))
1355 else if (unlikely(!w
))
1356 lw
->inv_weight
= WMULT_CONST
;
1358 lw
->inv_weight
= WMULT_CONST
/ w
;
1362 * Check whether we'd overflow the 64-bit multiplication:
1364 if (unlikely(tmp
> WMULT_CONST
))
1365 tmp
= SRR(SRR(tmp
, WMULT_SHIFT
/2) * lw
->inv_weight
,
1368 tmp
= SRR(tmp
* lw
->inv_weight
, WMULT_SHIFT
);
1370 return (unsigned long)min(tmp
, (u64
)(unsigned long)LONG_MAX
);
1373 static inline void update_load_add(struct load_weight
*lw
, unsigned long inc
)
1379 static inline void update_load_sub(struct load_weight
*lw
, unsigned long dec
)
1385 static inline void update_load_set(struct load_weight
*lw
, unsigned long w
)
1392 * To aid in avoiding the subversion of "niceness" due to uneven distribution
1393 * of tasks with abnormal "nice" values across CPUs the contribution that
1394 * each task makes to its run queue's load is weighted according to its
1395 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
1396 * scaled version of the new time slice allocation that they receive on time
1400 #define WEIGHT_IDLEPRIO 3
1401 #define WMULT_IDLEPRIO 1431655765
1404 * Nice levels are multiplicative, with a gentle 10% change for every
1405 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
1406 * nice 1, it will get ~10% less CPU time than another CPU-bound task
1407 * that remained on nice 0.
1409 * The "10% effect" is relative and cumulative: from _any_ nice level,
1410 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
1411 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
1412 * If a task goes up by ~10% and another task goes down by ~10% then
1413 * the relative distance between them is ~25%.)
1415 static const int prio_to_weight
[40] = {
1416 /* -20 */ 88761, 71755, 56483, 46273, 36291,
1417 /* -15 */ 29154, 23254, 18705, 14949, 11916,
1418 /* -10 */ 9548, 7620, 6100, 4904, 3906,
1419 /* -5 */ 3121, 2501, 1991, 1586, 1277,
1420 /* 0 */ 1024, 820, 655, 526, 423,
1421 /* 5 */ 335, 272, 215, 172, 137,
1422 /* 10 */ 110, 87, 70, 56, 45,
1423 /* 15 */ 36, 29, 23, 18, 15,
1427 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
1429 * In cases where the weight does not change often, we can use the
1430 * precalculated inverse to speed up arithmetics by turning divisions
1431 * into multiplications:
1433 static const u32 prio_to_wmult
[40] = {
1434 /* -20 */ 48388, 59856, 76040, 92818, 118348,
1435 /* -15 */ 147320, 184698, 229616, 287308, 360437,
1436 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
1437 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
1438 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
1439 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
1440 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
1441 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
1444 /* Time spent by the tasks of the cpu accounting group executing in ... */
1445 enum cpuacct_stat_index
{
1446 CPUACCT_STAT_USER
, /* ... user mode */
1447 CPUACCT_STAT_SYSTEM
, /* ... kernel mode */
1449 CPUACCT_STAT_NSTATS
,
1452 #ifdef CONFIG_CGROUP_CPUACCT
1453 static void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
);
1454 static void cpuacct_update_stats(struct task_struct
*tsk
,
1455 enum cpuacct_stat_index idx
, cputime_t val
);
1457 static inline void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
) {}
1458 static inline void cpuacct_update_stats(struct task_struct
*tsk
,
1459 enum cpuacct_stat_index idx
, cputime_t val
) {}
1462 static inline void inc_cpu_load(struct rq
*rq
, unsigned long load
)
1464 update_load_add(&rq
->load
, load
);
1467 static inline void dec_cpu_load(struct rq
*rq
, unsigned long load
)
1469 update_load_sub(&rq
->load
, load
);
1472 #if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) || defined(CONFIG_RT_GROUP_SCHED)
1473 typedef int (*tg_visitor
)(struct task_group
*, void *);
1476 * Iterate the full tree, calling @down when first entering a node and @up when
1477 * leaving it for the final time.
1479 static int walk_tg_tree(tg_visitor down
, tg_visitor up
, void *data
)
1481 struct task_group
*parent
, *child
;
1485 parent
= &root_task_group
;
1487 ret
= (*down
)(parent
, data
);
1490 list_for_each_entry_rcu(child
, &parent
->children
, siblings
) {
1497 ret
= (*up
)(parent
, data
);
1502 parent
= parent
->parent
;
1511 static int tg_nop(struct task_group
*tg
, void *data
)
1518 /* Used instead of source_load when we know the type == 0 */
1519 static unsigned long weighted_cpuload(const int cpu
)
1521 return cpu_rq(cpu
)->load
.weight
;
1525 * Return a low guess at the load of a migration-source cpu weighted
1526 * according to the scheduling class and "nice" value.
1528 * We want to under-estimate the load of migration sources, to
1529 * balance conservatively.
1531 static unsigned long source_load(int cpu
, int type
)
1533 struct rq
*rq
= cpu_rq(cpu
);
1534 unsigned long total
= weighted_cpuload(cpu
);
1536 if (type
== 0 || !sched_feat(LB_BIAS
))
1539 return min(rq
->cpu_load
[type
-1], total
);
1543 * Return a high guess at the load of a migration-target cpu weighted
1544 * according to the scheduling class and "nice" value.
1546 static unsigned long target_load(int cpu
, int type
)
1548 struct rq
*rq
= cpu_rq(cpu
);
1549 unsigned long total
= weighted_cpuload(cpu
);
1551 if (type
== 0 || !sched_feat(LB_BIAS
))
1554 return max(rq
->cpu_load
[type
-1], total
);
1557 static unsigned long power_of(int cpu
)
1559 return cpu_rq(cpu
)->cpu_power
;
1562 static int task_hot(struct task_struct
*p
, u64 now
, struct sched_domain
*sd
);
1564 static unsigned long cpu_avg_load_per_task(int cpu
)
1566 struct rq
*rq
= cpu_rq(cpu
);
1567 unsigned long nr_running
= ACCESS_ONCE(rq
->nr_running
);
1570 return rq
->load
.weight
/ nr_running
;
1575 #ifdef CONFIG_PREEMPT
1577 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
);
1580 * fair double_lock_balance: Safely acquires both rq->locks in a fair
1581 * way at the expense of forcing extra atomic operations in all
1582 * invocations. This assures that the double_lock is acquired using the
1583 * same underlying policy as the spinlock_t on this architecture, which
1584 * reduces latency compared to the unfair variant below. However, it
1585 * also adds more overhead and therefore may reduce throughput.
1587 static inline int _double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
1588 __releases(this_rq
->lock
)
1589 __acquires(busiest
->lock
)
1590 __acquires(this_rq
->lock
)
1592 raw_spin_unlock(&this_rq
->lock
);
1593 double_rq_lock(this_rq
, busiest
);
1600 * Unfair double_lock_balance: Optimizes throughput at the expense of
1601 * latency by eliminating extra atomic operations when the locks are
1602 * already in proper order on entry. This favors lower cpu-ids and will
1603 * grant the double lock to lower cpus over higher ids under contention,
1604 * regardless of entry order into the function.
1606 static int _double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
1607 __releases(this_rq
->lock
)
1608 __acquires(busiest
->lock
)
1609 __acquires(this_rq
->lock
)
1613 if (unlikely(!raw_spin_trylock(&busiest
->lock
))) {
1614 if (busiest
< this_rq
) {
1615 raw_spin_unlock(&this_rq
->lock
);
1616 raw_spin_lock(&busiest
->lock
);
1617 raw_spin_lock_nested(&this_rq
->lock
,
1618 SINGLE_DEPTH_NESTING
);
1621 raw_spin_lock_nested(&busiest
->lock
,
1622 SINGLE_DEPTH_NESTING
);
1627 #endif /* CONFIG_PREEMPT */
1630 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1632 static int double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
1634 if (unlikely(!irqs_disabled())) {
1635 /* printk() doesn't work good under rq->lock */
1636 raw_spin_unlock(&this_rq
->lock
);
1640 return _double_lock_balance(this_rq
, busiest
);
1643 static inline void double_unlock_balance(struct rq
*this_rq
, struct rq
*busiest
)
1644 __releases(busiest
->lock
)
1646 raw_spin_unlock(&busiest
->lock
);
1647 lock_set_subclass(&this_rq
->lock
.dep_map
, 0, _RET_IP_
);
1651 * double_rq_lock - safely lock two runqueues
1653 * Note this does not disable interrupts like task_rq_lock,
1654 * you need to do so manually before calling.
1656 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
1657 __acquires(rq1
->lock
)
1658 __acquires(rq2
->lock
)
1660 BUG_ON(!irqs_disabled());
1662 raw_spin_lock(&rq1
->lock
);
1663 __acquire(rq2
->lock
); /* Fake it out ;) */
1666 raw_spin_lock(&rq1
->lock
);
1667 raw_spin_lock_nested(&rq2
->lock
, SINGLE_DEPTH_NESTING
);
1669 raw_spin_lock(&rq2
->lock
);
1670 raw_spin_lock_nested(&rq1
->lock
, SINGLE_DEPTH_NESTING
);
1676 * double_rq_unlock - safely unlock two runqueues
1678 * Note this does not restore interrupts like task_rq_unlock,
1679 * you need to do so manually after calling.
1681 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
1682 __releases(rq1
->lock
)
1683 __releases(rq2
->lock
)
1685 raw_spin_unlock(&rq1
->lock
);
1687 raw_spin_unlock(&rq2
->lock
);
1689 __release(rq2
->lock
);
1692 #else /* CONFIG_SMP */
1695 * double_rq_lock - safely lock two runqueues
1697 * Note this does not disable interrupts like task_rq_lock,
1698 * you need to do so manually before calling.
1700 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
1701 __acquires(rq1
->lock
)
1702 __acquires(rq2
->lock
)
1704 BUG_ON(!irqs_disabled());
1706 raw_spin_lock(&rq1
->lock
);
1707 __acquire(rq2
->lock
); /* Fake it out ;) */
1711 * double_rq_unlock - safely unlock two runqueues
1713 * Note this does not restore interrupts like task_rq_unlock,
1714 * you need to do so manually after calling.
1716 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
1717 __releases(rq1
->lock
)
1718 __releases(rq2
->lock
)
1721 raw_spin_unlock(&rq1
->lock
);
1722 __release(rq2
->lock
);
1727 static void calc_load_account_idle(struct rq
*this_rq
);
1728 static void update_sysctl(void);
1729 static int get_update_sysctl_factor(void);
1730 static void update_cpu_load(struct rq
*this_rq
);
1732 static inline void __set_task_cpu(struct task_struct
*p
, unsigned int cpu
)
1734 set_task_rq(p
, cpu
);
1737 * After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
1738 * successfuly executed on another CPU. We must ensure that updates of
1739 * per-task data have been completed by this moment.
1742 task_thread_info(p
)->cpu
= cpu
;
1746 static const struct sched_class rt_sched_class
;
1748 #define sched_class_highest (&stop_sched_class)
1749 #define for_each_class(class) \
1750 for (class = sched_class_highest; class; class = class->next)
1752 #include "sched_stats.h"
1754 static void inc_nr_running(struct rq
*rq
)
1759 static void dec_nr_running(struct rq
*rq
)
1764 static void set_load_weight(struct task_struct
*p
)
1766 int prio
= p
->static_prio
- MAX_RT_PRIO
;
1767 struct load_weight
*load
= &p
->se
.load
;
1770 * SCHED_IDLE tasks get minimal weight:
1772 if (p
->policy
== SCHED_IDLE
) {
1773 load
->weight
= scale_load(WEIGHT_IDLEPRIO
);
1774 load
->inv_weight
= WMULT_IDLEPRIO
;
1778 load
->weight
= scale_load(prio_to_weight
[prio
]);
1779 load
->inv_weight
= prio_to_wmult
[prio
];
1782 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
1784 update_rq_clock(rq
);
1785 sched_info_queued(p
);
1786 p
->sched_class
->enqueue_task(rq
, p
, flags
);
1789 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
1791 update_rq_clock(rq
);
1792 sched_info_dequeued(p
);
1793 p
->sched_class
->dequeue_task(rq
, p
, flags
);
1797 * activate_task - move a task to the runqueue.
1799 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
1801 if (task_contributes_to_load(p
))
1802 rq
->nr_uninterruptible
--;
1804 enqueue_task(rq
, p
, flags
);
1808 * deactivate_task - remove a task from the runqueue.
1810 static void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
1812 if (task_contributes_to_load(p
))
1813 rq
->nr_uninterruptible
++;
1815 dequeue_task(rq
, p
, flags
);
1818 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
1821 * There are no locks covering percpu hardirq/softirq time.
1822 * They are only modified in account_system_vtime, on corresponding CPU
1823 * with interrupts disabled. So, writes are safe.
1824 * They are read and saved off onto struct rq in update_rq_clock().
1825 * This may result in other CPU reading this CPU's irq time and can
1826 * race with irq/account_system_vtime on this CPU. We would either get old
1827 * or new value with a side effect of accounting a slice of irq time to wrong
1828 * task when irq is in progress while we read rq->clock. That is a worthy
1829 * compromise in place of having locks on each irq in account_system_time.
1831 static DEFINE_PER_CPU(u64
, cpu_hardirq_time
);
1832 static DEFINE_PER_CPU(u64
, cpu_softirq_time
);
1834 static DEFINE_PER_CPU(u64
, irq_start_time
);
1835 static int sched_clock_irqtime
;
1837 void enable_sched_clock_irqtime(void)
1839 sched_clock_irqtime
= 1;
1842 void disable_sched_clock_irqtime(void)
1844 sched_clock_irqtime
= 0;
1847 #ifndef CONFIG_64BIT
1848 static DEFINE_PER_CPU(seqcount_t
, irq_time_seq
);
1850 static inline void irq_time_write_begin(void)
1852 __this_cpu_inc(irq_time_seq
.sequence
);
1856 static inline void irq_time_write_end(void)
1859 __this_cpu_inc(irq_time_seq
.sequence
);
1862 static inline u64
irq_time_read(int cpu
)
1868 seq
= read_seqcount_begin(&per_cpu(irq_time_seq
, cpu
));
1869 irq_time
= per_cpu(cpu_softirq_time
, cpu
) +
1870 per_cpu(cpu_hardirq_time
, cpu
);
1871 } while (read_seqcount_retry(&per_cpu(irq_time_seq
, cpu
), seq
));
1875 #else /* CONFIG_64BIT */
1876 static inline void irq_time_write_begin(void)
1880 static inline void irq_time_write_end(void)
1884 static inline u64
irq_time_read(int cpu
)
1886 return per_cpu(cpu_softirq_time
, cpu
) + per_cpu(cpu_hardirq_time
, cpu
);
1888 #endif /* CONFIG_64BIT */
1891 * Called before incrementing preempt_count on {soft,}irq_enter
1892 * and before decrementing preempt_count on {soft,}irq_exit.
1894 void account_system_vtime(struct task_struct
*curr
)
1896 unsigned long flags
;
1900 if (!sched_clock_irqtime
)
1903 local_irq_save(flags
);
1905 cpu
= smp_processor_id();
1906 delta
= sched_clock_cpu(cpu
) - __this_cpu_read(irq_start_time
);
1907 __this_cpu_add(irq_start_time
, delta
);
1909 irq_time_write_begin();
1911 * We do not account for softirq time from ksoftirqd here.
1912 * We want to continue accounting softirq time to ksoftirqd thread
1913 * in that case, so as not to confuse scheduler with a special task
1914 * that do not consume any time, but still wants to run.
1916 if (hardirq_count())
1917 __this_cpu_add(cpu_hardirq_time
, delta
);
1918 else if (in_serving_softirq() && curr
!= this_cpu_ksoftirqd())
1919 __this_cpu_add(cpu_softirq_time
, delta
);
1921 irq_time_write_end();
1922 local_irq_restore(flags
);
1924 EXPORT_SYMBOL_GPL(account_system_vtime
);
1926 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
1928 #ifdef CONFIG_PARAVIRT
1929 static inline u64
steal_ticks(u64 steal
)
1931 if (unlikely(steal
> NSEC_PER_SEC
))
1932 return div_u64(steal
, TICK_NSEC
);
1934 return __iter_div_u64_rem(steal
, TICK_NSEC
, &steal
);
1938 static void update_rq_clock_task(struct rq
*rq
, s64 delta
)
1941 * In theory, the compile should just see 0 here, and optimize out the call
1942 * to sched_rt_avg_update. But I don't trust it...
1944 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
1945 s64 steal
= 0, irq_delta
= 0;
1947 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
1948 irq_delta
= irq_time_read(cpu_of(rq
)) - rq
->prev_irq_time
;
1951 * Since irq_time is only updated on {soft,}irq_exit, we might run into
1952 * this case when a previous update_rq_clock() happened inside a
1953 * {soft,}irq region.
1955 * When this happens, we stop ->clock_task and only update the
1956 * prev_irq_time stamp to account for the part that fit, so that a next
1957 * update will consume the rest. This ensures ->clock_task is
1960 * It does however cause some slight miss-attribution of {soft,}irq
1961 * time, a more accurate solution would be to update the irq_time using
1962 * the current rq->clock timestamp, except that would require using
1965 if (irq_delta
> delta
)
1968 rq
->prev_irq_time
+= irq_delta
;
1971 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
1972 if (static_branch((¶virt_steal_rq_enabled
))) {
1975 steal
= paravirt_steal_clock(cpu_of(rq
));
1976 steal
-= rq
->prev_steal_time_rq
;
1978 if (unlikely(steal
> delta
))
1981 st
= steal_ticks(steal
);
1982 steal
= st
* TICK_NSEC
;
1984 rq
->prev_steal_time_rq
+= steal
;
1990 rq
->clock_task
+= delta
;
1992 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
1993 if ((irq_delta
+ steal
) && sched_feat(NONTASK_POWER
))
1994 sched_rt_avg_update(rq
, irq_delta
+ steal
);
1998 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
1999 static int irqtime_account_hi_update(void)
2001 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2002 unsigned long flags
;
2006 local_irq_save(flags
);
2007 latest_ns
= this_cpu_read(cpu_hardirq_time
);
2008 if (cputime64_gt(nsecs_to_cputime64(latest_ns
), cpustat
->irq
))
2010 local_irq_restore(flags
);
2014 static int irqtime_account_si_update(void)
2016 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2017 unsigned long flags
;
2021 local_irq_save(flags
);
2022 latest_ns
= this_cpu_read(cpu_softirq_time
);
2023 if (cputime64_gt(nsecs_to_cputime64(latest_ns
), cpustat
->softirq
))
2025 local_irq_restore(flags
);
2029 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
2031 #define sched_clock_irqtime (0)
2035 #include "sched_idletask.c"
2036 #include "sched_fair.c"
2037 #include "sched_rt.c"
2038 #include "sched_autogroup.c"
2039 #include "sched_stoptask.c"
2040 #ifdef CONFIG_SCHED_DEBUG
2041 # include "sched_debug.c"
2044 void sched_set_stop_task(int cpu
, struct task_struct
*stop
)
2046 struct sched_param param
= { .sched_priority
= MAX_RT_PRIO
- 1 };
2047 struct task_struct
*old_stop
= cpu_rq(cpu
)->stop
;
2051 * Make it appear like a SCHED_FIFO task, its something
2052 * userspace knows about and won't get confused about.
2054 * Also, it will make PI more or less work without too
2055 * much confusion -- but then, stop work should not
2056 * rely on PI working anyway.
2058 sched_setscheduler_nocheck(stop
, SCHED_FIFO
, ¶m
);
2060 stop
->sched_class
= &stop_sched_class
;
2063 cpu_rq(cpu
)->stop
= stop
;
2067 * Reset it back to a normal scheduling class so that
2068 * it can die in pieces.
2070 old_stop
->sched_class
= &rt_sched_class
;
2075 * __normal_prio - return the priority that is based on the static prio
2077 static inline int __normal_prio(struct task_struct
*p
)
2079 return p
->static_prio
;
2083 * Calculate the expected normal priority: i.e. priority
2084 * without taking RT-inheritance into account. Might be
2085 * boosted by interactivity modifiers. Changes upon fork,
2086 * setprio syscalls, and whenever the interactivity
2087 * estimator recalculates.
2089 static inline int normal_prio(struct task_struct
*p
)
2093 if (task_has_rt_policy(p
))
2094 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
2096 prio
= __normal_prio(p
);
2101 * Calculate the current priority, i.e. the priority
2102 * taken into account by the scheduler. This value might
2103 * be boosted by RT tasks, or might be boosted by
2104 * interactivity modifiers. Will be RT if the task got
2105 * RT-boosted. If not then it returns p->normal_prio.
2107 static int effective_prio(struct task_struct
*p
)
2109 p
->normal_prio
= normal_prio(p
);
2111 * If we are RT tasks or we were boosted to RT priority,
2112 * keep the priority unchanged. Otherwise, update priority
2113 * to the normal priority:
2115 if (!rt_prio(p
->prio
))
2116 return p
->normal_prio
;
2121 * task_curr - is this task currently executing on a CPU?
2122 * @p: the task in question.
2124 inline int task_curr(const struct task_struct
*p
)
2126 return cpu_curr(task_cpu(p
)) == p
;
2129 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
2130 const struct sched_class
*prev_class
,
2133 if (prev_class
!= p
->sched_class
) {
2134 if (prev_class
->switched_from
)
2135 prev_class
->switched_from(rq
, p
);
2136 p
->sched_class
->switched_to(rq
, p
);
2137 } else if (oldprio
!= p
->prio
)
2138 p
->sched_class
->prio_changed(rq
, p
, oldprio
);
2141 static void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
, int flags
)
2143 const struct sched_class
*class;
2145 if (p
->sched_class
== rq
->curr
->sched_class
) {
2146 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
, flags
);
2148 for_each_class(class) {
2149 if (class == rq
->curr
->sched_class
)
2151 if (class == p
->sched_class
) {
2152 resched_task(rq
->curr
);
2159 * A queue event has occurred, and we're going to schedule. In
2160 * this case, we can save a useless back to back clock update.
2162 if (rq
->curr
->on_rq
&& test_tsk_need_resched(rq
->curr
))
2163 rq
->skip_clock_update
= 1;
2168 * Is this task likely cache-hot:
2171 task_hot(struct task_struct
*p
, u64 now
, struct sched_domain
*sd
)
2175 if (p
->sched_class
!= &fair_sched_class
)
2178 if (unlikely(p
->policy
== SCHED_IDLE
))
2182 * Buddy candidates are cache hot:
2184 if (sched_feat(CACHE_HOT_BUDDY
) && this_rq()->nr_running
&&
2185 (&p
->se
== cfs_rq_of(&p
->se
)->next
||
2186 &p
->se
== cfs_rq_of(&p
->se
)->last
))
2189 if (sysctl_sched_migration_cost
== -1)
2191 if (sysctl_sched_migration_cost
== 0)
2194 delta
= now
- p
->se
.exec_start
;
2196 return delta
< (s64
)sysctl_sched_migration_cost
;
2199 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
2201 #ifdef CONFIG_SCHED_DEBUG
2203 * We should never call set_task_cpu() on a blocked task,
2204 * ttwu() will sort out the placement.
2206 WARN_ON_ONCE(p
->state
!= TASK_RUNNING
&& p
->state
!= TASK_WAKING
&&
2207 !(task_thread_info(p
)->preempt_count
& PREEMPT_ACTIVE
));
2209 #ifdef CONFIG_LOCKDEP
2211 * The caller should hold either p->pi_lock or rq->lock, when changing
2212 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
2214 * sched_move_task() holds both and thus holding either pins the cgroup,
2215 * see set_task_rq().
2217 * Furthermore, all task_rq users should acquire both locks, see
2220 WARN_ON_ONCE(debug_locks
&& !(lockdep_is_held(&p
->pi_lock
) ||
2221 lockdep_is_held(&task_rq(p
)->lock
)));
2225 trace_sched_migrate_task(p
, new_cpu
);
2227 if (task_cpu(p
) != new_cpu
) {
2228 p
->se
.nr_migrations
++;
2229 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS
, 1, NULL
, 0);
2232 __set_task_cpu(p
, new_cpu
);
2235 struct migration_arg
{
2236 struct task_struct
*task
;
2240 static int migration_cpu_stop(void *data
);
2243 * wait_task_inactive - wait for a thread to unschedule.
2245 * If @match_state is nonzero, it's the @p->state value just checked and
2246 * not expected to change. If it changes, i.e. @p might have woken up,
2247 * then return zero. When we succeed in waiting for @p to be off its CPU,
2248 * we return a positive number (its total switch count). If a second call
2249 * a short while later returns the same number, the caller can be sure that
2250 * @p has remained unscheduled the whole time.
2252 * The caller must ensure that the task *will* unschedule sometime soon,
2253 * else this function might spin for a *long* time. This function can't
2254 * be called with interrupts off, or it may introduce deadlock with
2255 * smp_call_function() if an IPI is sent by the same process we are
2256 * waiting to become inactive.
2258 unsigned long wait_task_inactive(struct task_struct
*p
, long match_state
)
2260 unsigned long flags
;
2267 * We do the initial early heuristics without holding
2268 * any task-queue locks at all. We'll only try to get
2269 * the runqueue lock when things look like they will
2275 * If the task is actively running on another CPU
2276 * still, just relax and busy-wait without holding
2279 * NOTE! Since we don't hold any locks, it's not
2280 * even sure that "rq" stays as the right runqueue!
2281 * But we don't care, since "task_running()" will
2282 * return false if the runqueue has changed and p
2283 * is actually now running somewhere else!
2285 while (task_running(rq
, p
)) {
2286 if (match_state
&& unlikely(p
->state
!= match_state
))
2292 * Ok, time to look more closely! We need the rq
2293 * lock now, to be *sure*. If we're wrong, we'll
2294 * just go back and repeat.
2296 rq
= task_rq_lock(p
, &flags
);
2297 trace_sched_wait_task(p
);
2298 running
= task_running(rq
, p
);
2301 if (!match_state
|| p
->state
== match_state
)
2302 ncsw
= p
->nvcsw
| LONG_MIN
; /* sets MSB */
2303 task_rq_unlock(rq
, p
, &flags
);
2306 * If it changed from the expected state, bail out now.
2308 if (unlikely(!ncsw
))
2312 * Was it really running after all now that we
2313 * checked with the proper locks actually held?
2315 * Oops. Go back and try again..
2317 if (unlikely(running
)) {
2323 * It's not enough that it's not actively running,
2324 * it must be off the runqueue _entirely_, and not
2327 * So if it was still runnable (but just not actively
2328 * running right now), it's preempted, and we should
2329 * yield - it could be a while.
2331 if (unlikely(on_rq
)) {
2332 ktime_t to
= ktime_set(0, NSEC_PER_SEC
/HZ
);
2334 set_current_state(TASK_UNINTERRUPTIBLE
);
2335 schedule_hrtimeout(&to
, HRTIMER_MODE_REL
);
2340 * Ahh, all good. It wasn't running, and it wasn't
2341 * runnable, which means that it will never become
2342 * running in the future either. We're all done!
2351 * kick_process - kick a running thread to enter/exit the kernel
2352 * @p: the to-be-kicked thread
2354 * Cause a process which is running on another CPU to enter
2355 * kernel-mode, without any delay. (to get signals handled.)
2357 * NOTE: this function doesn't have to take the runqueue lock,
2358 * because all it wants to ensure is that the remote task enters
2359 * the kernel. If the IPI races and the task has been migrated
2360 * to another CPU then no harm is done and the purpose has been
2363 void kick_process(struct task_struct
*p
)
2369 if ((cpu
!= smp_processor_id()) && task_curr(p
))
2370 smp_send_reschedule(cpu
);
2373 EXPORT_SYMBOL_GPL(kick_process
);
2374 #endif /* CONFIG_SMP */
2378 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
2380 static int select_fallback_rq(int cpu
, struct task_struct
*p
)
2383 const struct cpumask
*nodemask
= cpumask_of_node(cpu_to_node(cpu
));
2385 /* Look for allowed, online CPU in same node. */
2386 for_each_cpu_and(dest_cpu
, nodemask
, cpu_active_mask
)
2387 if (cpumask_test_cpu(dest_cpu
, &p
->cpus_allowed
))
2390 /* Any allowed, online CPU? */
2391 dest_cpu
= cpumask_any_and(&p
->cpus_allowed
, cpu_active_mask
);
2392 if (dest_cpu
< nr_cpu_ids
)
2395 /* No more Mr. Nice Guy. */
2396 dest_cpu
= cpuset_cpus_allowed_fallback(p
);
2398 * Don't tell them about moving exiting tasks or
2399 * kernel threads (both mm NULL), since they never
2402 if (p
->mm
&& printk_ratelimit()) {
2403 printk(KERN_INFO
"process %d (%s) no longer affine to cpu%d\n",
2404 task_pid_nr(p
), p
->comm
, cpu
);
2411 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
2414 int select_task_rq(struct task_struct
*p
, int sd_flags
, int wake_flags
)
2416 int cpu
= p
->sched_class
->select_task_rq(p
, sd_flags
, wake_flags
);
2419 * In order not to call set_task_cpu() on a blocking task we need
2420 * to rely on ttwu() to place the task on a valid ->cpus_allowed
2423 * Since this is common to all placement strategies, this lives here.
2425 * [ this allows ->select_task() to simply return task_cpu(p) and
2426 * not worry about this generic constraint ]
2428 if (unlikely(!cpumask_test_cpu(cpu
, &p
->cpus_allowed
) ||
2430 cpu
= select_fallback_rq(task_cpu(p
), p
);
2435 static void update_avg(u64
*avg
, u64 sample
)
2437 s64 diff
= sample
- *avg
;
2443 ttwu_stat(struct task_struct
*p
, int cpu
, int wake_flags
)
2445 #ifdef CONFIG_SCHEDSTATS
2446 struct rq
*rq
= this_rq();
2449 int this_cpu
= smp_processor_id();
2451 if (cpu
== this_cpu
) {
2452 schedstat_inc(rq
, ttwu_local
);
2453 schedstat_inc(p
, se
.statistics
.nr_wakeups_local
);
2455 struct sched_domain
*sd
;
2457 schedstat_inc(p
, se
.statistics
.nr_wakeups_remote
);
2459 for_each_domain(this_cpu
, sd
) {
2460 if (cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
2461 schedstat_inc(sd
, ttwu_wake_remote
);
2468 if (wake_flags
& WF_MIGRATED
)
2469 schedstat_inc(p
, se
.statistics
.nr_wakeups_migrate
);
2471 #endif /* CONFIG_SMP */
2473 schedstat_inc(rq
, ttwu_count
);
2474 schedstat_inc(p
, se
.statistics
.nr_wakeups
);
2476 if (wake_flags
& WF_SYNC
)
2477 schedstat_inc(p
, se
.statistics
.nr_wakeups_sync
);
2479 #endif /* CONFIG_SCHEDSTATS */
2482 static void ttwu_activate(struct rq
*rq
, struct task_struct
*p
, int en_flags
)
2484 activate_task(rq
, p
, en_flags
);
2487 /* if a worker is waking up, notify workqueue */
2488 if (p
->flags
& PF_WQ_WORKER
)
2489 wq_worker_waking_up(p
, cpu_of(rq
));
2493 * Mark the task runnable and perform wakeup-preemption.
2496 ttwu_do_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
2498 trace_sched_wakeup(p
, true);
2499 check_preempt_curr(rq
, p
, wake_flags
);
2501 p
->state
= TASK_RUNNING
;
2503 if (p
->sched_class
->task_woken
)
2504 p
->sched_class
->task_woken(rq
, p
);
2506 if (rq
->idle_stamp
) {
2507 u64 delta
= rq
->clock
- rq
->idle_stamp
;
2508 u64 max
= 2*sysctl_sched_migration_cost
;
2513 update_avg(&rq
->avg_idle
, delta
);
2520 ttwu_do_activate(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
2523 if (p
->sched_contributes_to_load
)
2524 rq
->nr_uninterruptible
--;
2527 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
| ENQUEUE_WAKING
);
2528 ttwu_do_wakeup(rq
, p
, wake_flags
);
2532 * Called in case the task @p isn't fully descheduled from its runqueue,
2533 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
2534 * since all we need to do is flip p->state to TASK_RUNNING, since
2535 * the task is still ->on_rq.
2537 static int ttwu_remote(struct task_struct
*p
, int wake_flags
)
2542 rq
= __task_rq_lock(p
);
2544 ttwu_do_wakeup(rq
, p
, wake_flags
);
2547 __task_rq_unlock(rq
);
2553 static void sched_ttwu_do_pending(struct task_struct
*list
)
2555 struct rq
*rq
= this_rq();
2557 raw_spin_lock(&rq
->lock
);
2560 struct task_struct
*p
= list
;
2561 list
= list
->wake_entry
;
2562 ttwu_do_activate(rq
, p
, 0);
2565 raw_spin_unlock(&rq
->lock
);
2568 #ifdef CONFIG_HOTPLUG_CPU
2570 static void sched_ttwu_pending(void)
2572 struct rq
*rq
= this_rq();
2573 struct task_struct
*list
= xchg(&rq
->wake_list
, NULL
);
2578 sched_ttwu_do_pending(list
);
2581 #endif /* CONFIG_HOTPLUG_CPU */
2583 void scheduler_ipi(void)
2585 struct rq
*rq
= this_rq();
2586 struct task_struct
*list
= xchg(&rq
->wake_list
, NULL
);
2592 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
2593 * traditionally all their work was done from the interrupt return
2594 * path. Now that we actually do some work, we need to make sure
2597 * Some archs already do call them, luckily irq_enter/exit nest
2600 * Arguably we should visit all archs and update all handlers,
2601 * however a fair share of IPIs are still resched only so this would
2602 * somewhat pessimize the simple resched case.
2605 sched_ttwu_do_pending(list
);
2609 static void ttwu_queue_remote(struct task_struct
*p
, int cpu
)
2611 struct rq
*rq
= cpu_rq(cpu
);
2612 struct task_struct
*next
= rq
->wake_list
;
2615 struct task_struct
*old
= next
;
2617 p
->wake_entry
= next
;
2618 next
= cmpxchg(&rq
->wake_list
, old
, p
);
2624 smp_send_reschedule(cpu
);
2627 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
2628 static int ttwu_activate_remote(struct task_struct
*p
, int wake_flags
)
2633 rq
= __task_rq_lock(p
);
2635 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
);
2636 ttwu_do_wakeup(rq
, p
, wake_flags
);
2639 __task_rq_unlock(rq
);
2644 #endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
2645 #endif /* CONFIG_SMP */
2647 static void ttwu_queue(struct task_struct
*p
, int cpu
)
2649 struct rq
*rq
= cpu_rq(cpu
);
2651 #if defined(CONFIG_SMP)
2652 if (sched_feat(TTWU_QUEUE
) && cpu
!= smp_processor_id()) {
2653 sched_clock_cpu(cpu
); /* sync clocks x-cpu */
2654 ttwu_queue_remote(p
, cpu
);
2659 raw_spin_lock(&rq
->lock
);
2660 ttwu_do_activate(rq
, p
, 0);
2661 raw_spin_unlock(&rq
->lock
);
2665 * try_to_wake_up - wake up a thread
2666 * @p: the thread to be awakened
2667 * @state: the mask of task states that can be woken
2668 * @wake_flags: wake modifier flags (WF_*)
2670 * Put it on the run-queue if it's not already there. The "current"
2671 * thread is always on the run-queue (except when the actual
2672 * re-schedule is in progress), and as such you're allowed to do
2673 * the simpler "current->state = TASK_RUNNING" to mark yourself
2674 * runnable without the overhead of this.
2676 * Returns %true if @p was woken up, %false if it was already running
2677 * or @state didn't match @p's state.
2680 try_to_wake_up(struct task_struct
*p
, unsigned int state
, int wake_flags
)
2682 unsigned long flags
;
2683 int cpu
, success
= 0;
2686 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2687 if (!(p
->state
& state
))
2690 success
= 1; /* we're going to change ->state */
2693 if (p
->on_rq
&& ttwu_remote(p
, wake_flags
))
2698 * If the owning (remote) cpu is still in the middle of schedule() with
2699 * this task as prev, wait until its done referencing the task.
2702 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
2704 * In case the architecture enables interrupts in
2705 * context_switch(), we cannot busy wait, since that
2706 * would lead to deadlocks when an interrupt hits and
2707 * tries to wake up @prev. So bail and do a complete
2710 if (ttwu_activate_remote(p
, wake_flags
))
2717 * Pairs with the smp_wmb() in finish_lock_switch().
2721 p
->sched_contributes_to_load
= !!task_contributes_to_load(p
);
2722 p
->state
= TASK_WAKING
;
2724 if (p
->sched_class
->task_waking
)
2725 p
->sched_class
->task_waking(p
);
2727 cpu
= select_task_rq(p
, SD_BALANCE_WAKE
, wake_flags
);
2728 if (task_cpu(p
) != cpu
) {
2729 wake_flags
|= WF_MIGRATED
;
2730 set_task_cpu(p
, cpu
);
2732 #endif /* CONFIG_SMP */
2736 ttwu_stat(p
, cpu
, wake_flags
);
2738 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2744 * try_to_wake_up_local - try to wake up a local task with rq lock held
2745 * @p: the thread to be awakened
2747 * Put @p on the run-queue if it's not already there. The caller must
2748 * ensure that this_rq() is locked, @p is bound to this_rq() and not
2751 static void try_to_wake_up_local(struct task_struct
*p
)
2753 struct rq
*rq
= task_rq(p
);
2755 BUG_ON(rq
!= this_rq());
2756 BUG_ON(p
== current
);
2757 lockdep_assert_held(&rq
->lock
);
2759 if (!raw_spin_trylock(&p
->pi_lock
)) {
2760 raw_spin_unlock(&rq
->lock
);
2761 raw_spin_lock(&p
->pi_lock
);
2762 raw_spin_lock(&rq
->lock
);
2765 if (!(p
->state
& TASK_NORMAL
))
2769 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
);
2771 ttwu_do_wakeup(rq
, p
, 0);
2772 ttwu_stat(p
, smp_processor_id(), 0);
2774 raw_spin_unlock(&p
->pi_lock
);
2778 * wake_up_process - Wake up a specific process
2779 * @p: The process to be woken up.
2781 * Attempt to wake up the nominated process and move it to the set of runnable
2782 * processes. Returns 1 if the process was woken up, 0 if it was already
2785 * It may be assumed that this function implies a write memory barrier before
2786 * changing the task state if and only if any tasks are woken up.
2788 int wake_up_process(struct task_struct
*p
)
2790 return try_to_wake_up(p
, TASK_ALL
, 0);
2792 EXPORT_SYMBOL(wake_up_process
);
2794 int wake_up_state(struct task_struct
*p
, unsigned int state
)
2796 return try_to_wake_up(p
, state
, 0);
2800 * Perform scheduler related setup for a newly forked process p.
2801 * p is forked by current.
2803 * __sched_fork() is basic setup used by init_idle() too:
2805 static void __sched_fork(struct task_struct
*p
)
2810 p
->se
.exec_start
= 0;
2811 p
->se
.sum_exec_runtime
= 0;
2812 p
->se
.prev_sum_exec_runtime
= 0;
2813 p
->se
.nr_migrations
= 0;
2815 INIT_LIST_HEAD(&p
->se
.group_node
);
2817 #ifdef CONFIG_SCHEDSTATS
2818 memset(&p
->se
.statistics
, 0, sizeof(p
->se
.statistics
));
2821 INIT_LIST_HEAD(&p
->rt
.run_list
);
2823 #ifdef CONFIG_PREEMPT_NOTIFIERS
2824 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
2829 * fork()/clone()-time setup:
2831 void sched_fork(struct task_struct
*p
)
2833 unsigned long flags
;
2834 int cpu
= get_cpu();
2838 * We mark the process as running here. This guarantees that
2839 * nobody will actually run it, and a signal or other external
2840 * event cannot wake it up and insert it on the runqueue either.
2842 p
->state
= TASK_RUNNING
;
2845 * Make sure we do not leak PI boosting priority to the child.
2847 p
->prio
= current
->normal_prio
;
2850 * Revert to default priority/policy on fork if requested.
2852 if (unlikely(p
->sched_reset_on_fork
)) {
2853 if (task_has_rt_policy(p
)) {
2854 p
->policy
= SCHED_NORMAL
;
2855 p
->static_prio
= NICE_TO_PRIO(0);
2857 } else if (PRIO_TO_NICE(p
->static_prio
) < 0)
2858 p
->static_prio
= NICE_TO_PRIO(0);
2860 p
->prio
= p
->normal_prio
= __normal_prio(p
);
2864 * We don't need the reset flag anymore after the fork. It has
2865 * fulfilled its duty:
2867 p
->sched_reset_on_fork
= 0;
2870 if (!rt_prio(p
->prio
))
2871 p
->sched_class
= &fair_sched_class
;
2873 if (p
->sched_class
->task_fork
)
2874 p
->sched_class
->task_fork(p
);
2877 * The child is not yet in the pid-hash so no cgroup attach races,
2878 * and the cgroup is pinned to this child due to cgroup_fork()
2879 * is ran before sched_fork().
2881 * Silence PROVE_RCU.
2883 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2884 set_task_cpu(p
, cpu
);
2885 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2887 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
2888 if (likely(sched_info_on()))
2889 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
2891 #if defined(CONFIG_SMP)
2894 #ifdef CONFIG_PREEMPT_COUNT
2895 /* Want to start with kernel preemption disabled. */
2896 task_thread_info(p
)->preempt_count
= 1;
2899 plist_node_init(&p
->pushable_tasks
, MAX_PRIO
);
2906 * wake_up_new_task - wake up a newly created task for the first time.
2908 * This function will do some initial scheduler statistics housekeeping
2909 * that must be done for every newly created context, then puts the task
2910 * on the runqueue and wakes it.
2912 void wake_up_new_task(struct task_struct
*p
)
2914 unsigned long flags
;
2917 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2920 * Fork balancing, do it here and not earlier because:
2921 * - cpus_allowed can change in the fork path
2922 * - any previously selected cpu might disappear through hotplug
2924 set_task_cpu(p
, select_task_rq(p
, SD_BALANCE_FORK
, 0));
2927 rq
= __task_rq_lock(p
);
2928 activate_task(rq
, p
, 0);
2930 trace_sched_wakeup_new(p
, true);
2931 check_preempt_curr(rq
, p
, WF_FORK
);
2933 if (p
->sched_class
->task_woken
)
2934 p
->sched_class
->task_woken(rq
, p
);
2936 task_rq_unlock(rq
, p
, &flags
);
2939 #ifdef CONFIG_PREEMPT_NOTIFIERS
2942 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2943 * @notifier: notifier struct to register
2945 void preempt_notifier_register(struct preempt_notifier
*notifier
)
2947 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
2949 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
2952 * preempt_notifier_unregister - no longer interested in preemption notifications
2953 * @notifier: notifier struct to unregister
2955 * This is safe to call from within a preemption notifier.
2957 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
2959 hlist_del(¬ifier
->link
);
2961 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
2963 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2965 struct preempt_notifier
*notifier
;
2966 struct hlist_node
*node
;
2968 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
2969 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
2973 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2974 struct task_struct
*next
)
2976 struct preempt_notifier
*notifier
;
2977 struct hlist_node
*node
;
2979 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
2980 notifier
->ops
->sched_out(notifier
, next
);
2983 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2985 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2990 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2991 struct task_struct
*next
)
2995 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2998 * prepare_task_switch - prepare to switch tasks
2999 * @rq: the runqueue preparing to switch
3000 * @prev: the current task that is being switched out
3001 * @next: the task we are going to switch to.
3003 * This is called with the rq lock held and interrupts off. It must
3004 * be paired with a subsequent finish_task_switch after the context
3007 * prepare_task_switch sets up locking and calls architecture specific
3011 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
3012 struct task_struct
*next
)
3014 sched_info_switch(prev
, next
);
3015 perf_event_task_sched_out(prev
, next
);
3016 fire_sched_out_preempt_notifiers(prev
, next
);
3017 prepare_lock_switch(rq
, next
);
3018 prepare_arch_switch(next
);
3019 trace_sched_switch(prev
, next
);
3023 * finish_task_switch - clean up after a task-switch
3024 * @rq: runqueue associated with task-switch
3025 * @prev: the thread we just switched away from.
3027 * finish_task_switch must be called after the context switch, paired
3028 * with a prepare_task_switch call before the context switch.
3029 * finish_task_switch will reconcile locking set up by prepare_task_switch,
3030 * and do any other architecture-specific cleanup actions.
3032 * Note that we may have delayed dropping an mm in context_switch(). If
3033 * so, we finish that here outside of the runqueue lock. (Doing it
3034 * with the lock held can cause deadlocks; see schedule() for
3037 static void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
3038 __releases(rq
->lock
)
3040 struct mm_struct
*mm
= rq
->prev_mm
;
3046 * A task struct has one reference for the use as "current".
3047 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
3048 * schedule one last time. The schedule call will never return, and
3049 * the scheduled task must drop that reference.
3050 * The test for TASK_DEAD must occur while the runqueue locks are
3051 * still held, otherwise prev could be scheduled on another cpu, die
3052 * there before we look at prev->state, and then the reference would
3054 * Manfred Spraul <manfred@colorfullife.com>
3056 prev_state
= prev
->state
;
3057 finish_arch_switch(prev
);
3058 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
3059 local_irq_disable();
3060 #endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
3061 perf_event_task_sched_in(current
);
3062 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
3064 #endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
3065 finish_lock_switch(rq
, prev
);
3067 fire_sched_in_preempt_notifiers(current
);
3070 if (unlikely(prev_state
== TASK_DEAD
)) {
3072 * Remove function-return probe instances associated with this
3073 * task and put them back on the free list.
3075 kprobe_flush_task(prev
);
3076 put_task_struct(prev
);
3082 /* assumes rq->lock is held */
3083 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*prev
)
3085 if (prev
->sched_class
->pre_schedule
)
3086 prev
->sched_class
->pre_schedule(rq
, prev
);
3089 /* rq->lock is NOT held, but preemption is disabled */
3090 static inline void post_schedule(struct rq
*rq
)
3092 if (rq
->post_schedule
) {
3093 unsigned long flags
;
3095 raw_spin_lock_irqsave(&rq
->lock
, flags
);
3096 if (rq
->curr
->sched_class
->post_schedule
)
3097 rq
->curr
->sched_class
->post_schedule(rq
);
3098 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
3100 rq
->post_schedule
= 0;
3106 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*p
)
3110 static inline void post_schedule(struct rq
*rq
)
3117 * schedule_tail - first thing a freshly forked thread must call.
3118 * @prev: the thread we just switched away from.
3120 asmlinkage
void schedule_tail(struct task_struct
*prev
)
3121 __releases(rq
->lock
)
3123 struct rq
*rq
= this_rq();
3125 finish_task_switch(rq
, prev
);
3128 * FIXME: do we need to worry about rq being invalidated by the
3133 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
3134 /* In this case, finish_task_switch does not reenable preemption */
3137 if (current
->set_child_tid
)
3138 put_user(task_pid_vnr(current
), current
->set_child_tid
);
3142 * context_switch - switch to the new MM and the new
3143 * thread's register state.
3146 context_switch(struct rq
*rq
, struct task_struct
*prev
,
3147 struct task_struct
*next
)
3149 struct mm_struct
*mm
, *oldmm
;
3151 prepare_task_switch(rq
, prev
, next
);
3154 oldmm
= prev
->active_mm
;
3156 * For paravirt, this is coupled with an exit in switch_to to
3157 * combine the page table reload and the switch backend into
3160 arch_start_context_switch(prev
);
3163 next
->active_mm
= oldmm
;
3164 atomic_inc(&oldmm
->mm_count
);
3165 enter_lazy_tlb(oldmm
, next
);
3167 switch_mm(oldmm
, mm
, next
);
3170 prev
->active_mm
= NULL
;
3171 rq
->prev_mm
= oldmm
;
3174 * Since the runqueue lock will be released by the next
3175 * task (which is an invalid locking op but in the case
3176 * of the scheduler it's an obvious special-case), so we
3177 * do an early lockdep release here:
3179 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
3180 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
3183 /* Here we just switch the register state and the stack. */
3184 switch_to(prev
, next
, prev
);
3188 * this_rq must be evaluated again because prev may have moved
3189 * CPUs since it called schedule(), thus the 'rq' on its stack
3190 * frame will be invalid.
3192 finish_task_switch(this_rq(), prev
);
3196 * nr_running, nr_uninterruptible and nr_context_switches:
3198 * externally visible scheduler statistics: current number of runnable
3199 * threads, current number of uninterruptible-sleeping threads, total
3200 * number of context switches performed since bootup.
3202 unsigned long nr_running(void)
3204 unsigned long i
, sum
= 0;
3206 for_each_online_cpu(i
)
3207 sum
+= cpu_rq(i
)->nr_running
;
3212 unsigned long nr_uninterruptible(void)
3214 unsigned long i
, sum
= 0;
3216 for_each_possible_cpu(i
)
3217 sum
+= cpu_rq(i
)->nr_uninterruptible
;
3220 * Since we read the counters lockless, it might be slightly
3221 * inaccurate. Do not allow it to go below zero though:
3223 if (unlikely((long)sum
< 0))
3229 unsigned long long nr_context_switches(void)
3232 unsigned long long sum
= 0;
3234 for_each_possible_cpu(i
)
3235 sum
+= cpu_rq(i
)->nr_switches
;
3240 unsigned long nr_iowait(void)
3242 unsigned long i
, sum
= 0;
3244 for_each_possible_cpu(i
)
3245 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
3250 unsigned long nr_iowait_cpu(int cpu
)
3252 struct rq
*this = cpu_rq(cpu
);
3253 return atomic_read(&this->nr_iowait
);
3256 unsigned long this_cpu_load(void)
3258 struct rq
*this = this_rq();
3259 return this->cpu_load
[0];
3263 /* Variables and functions for calc_load */
3264 static atomic_long_t calc_load_tasks
;
3265 static unsigned long calc_load_update
;
3266 unsigned long avenrun
[3];
3267 EXPORT_SYMBOL(avenrun
);
3269 static long calc_load_fold_active(struct rq
*this_rq
)
3271 long nr_active
, delta
= 0;
3273 nr_active
= this_rq
->nr_running
;
3274 nr_active
+= (long) this_rq
->nr_uninterruptible
;
3276 if (nr_active
!= this_rq
->calc_load_active
) {
3277 delta
= nr_active
- this_rq
->calc_load_active
;
3278 this_rq
->calc_load_active
= nr_active
;
3284 static unsigned long
3285 calc_load(unsigned long load
, unsigned long exp
, unsigned long active
)
3288 load
+= active
* (FIXED_1
- exp
);
3289 load
+= 1UL << (FSHIFT
- 1);
3290 return load
>> FSHIFT
;
3295 * For NO_HZ we delay the active fold to the next LOAD_FREQ update.
3297 * When making the ILB scale, we should try to pull this in as well.
3299 static atomic_long_t calc_load_tasks_idle
;
3301 static void calc_load_account_idle(struct rq
*this_rq
)
3305 delta
= calc_load_fold_active(this_rq
);
3307 atomic_long_add(delta
, &calc_load_tasks_idle
);
3310 static long calc_load_fold_idle(void)
3315 * Its got a race, we don't care...
3317 if (atomic_long_read(&calc_load_tasks_idle
))
3318 delta
= atomic_long_xchg(&calc_load_tasks_idle
, 0);
3324 * fixed_power_int - compute: x^n, in O(log n) time
3326 * @x: base of the power
3327 * @frac_bits: fractional bits of @x
3328 * @n: power to raise @x to.
3330 * By exploiting the relation between the definition of the natural power
3331 * function: x^n := x*x*...*x (x multiplied by itself for n times), and
3332 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
3333 * (where: n_i \elem {0, 1}, the binary vector representing n),
3334 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
3335 * of course trivially computable in O(log_2 n), the length of our binary
3338 static unsigned long
3339 fixed_power_int(unsigned long x
, unsigned int frac_bits
, unsigned int n
)
3341 unsigned long result
= 1UL << frac_bits
;
3346 result
+= 1UL << (frac_bits
- 1);
3347 result
>>= frac_bits
;
3353 x
+= 1UL << (frac_bits
- 1);
3361 * a1 = a0 * e + a * (1 - e)
3363 * a2 = a1 * e + a * (1 - e)
3364 * = (a0 * e + a * (1 - e)) * e + a * (1 - e)
3365 * = a0 * e^2 + a * (1 - e) * (1 + e)
3367 * a3 = a2 * e + a * (1 - e)
3368 * = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
3369 * = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
3373 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
3374 * = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
3375 * = a0 * e^n + a * (1 - e^n)
3377 * [1] application of the geometric series:
3380 * S_n := \Sum x^i = -------------
3383 static unsigned long
3384 calc_load_n(unsigned long load
, unsigned long exp
,
3385 unsigned long active
, unsigned int n
)
3388 return calc_load(load
, fixed_power_int(exp
, FSHIFT
, n
), active
);
3392 * NO_HZ can leave us missing all per-cpu ticks calling
3393 * calc_load_account_active(), but since an idle CPU folds its delta into
3394 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
3395 * in the pending idle delta if our idle period crossed a load cycle boundary.
3397 * Once we've updated the global active value, we need to apply the exponential
3398 * weights adjusted to the number of cycles missed.
3400 static void calc_global_nohz(unsigned long ticks
)
3402 long delta
, active
, n
;
3404 if (time_before(jiffies
, calc_load_update
))
3408 * If we crossed a calc_load_update boundary, make sure to fold
3409 * any pending idle changes, the respective CPUs might have
3410 * missed the tick driven calc_load_account_active() update
3413 delta
= calc_load_fold_idle();
3415 atomic_long_add(delta
, &calc_load_tasks
);
3418 * If we were idle for multiple load cycles, apply them.
3420 if (ticks
>= LOAD_FREQ
) {
3421 n
= ticks
/ LOAD_FREQ
;
3423 active
= atomic_long_read(&calc_load_tasks
);
3424 active
= active
> 0 ? active
* FIXED_1
: 0;
3426 avenrun
[0] = calc_load_n(avenrun
[0], EXP_1
, active
, n
);
3427 avenrun
[1] = calc_load_n(avenrun
[1], EXP_5
, active
, n
);
3428 avenrun
[2] = calc_load_n(avenrun
[2], EXP_15
, active
, n
);
3430 calc_load_update
+= n
* LOAD_FREQ
;
3434 * Its possible the remainder of the above division also crosses
3435 * a LOAD_FREQ period, the regular check in calc_global_load()
3436 * which comes after this will take care of that.
3438 * Consider us being 11 ticks before a cycle completion, and us
3439 * sleeping for 4*LOAD_FREQ + 22 ticks, then the above code will
3440 * age us 4 cycles, and the test in calc_global_load() will
3441 * pick up the final one.
3445 static void calc_load_account_idle(struct rq
*this_rq
)
3449 static inline long calc_load_fold_idle(void)
3454 static void calc_global_nohz(unsigned long ticks
)
3460 * get_avenrun - get the load average array
3461 * @loads: pointer to dest load array
3462 * @offset: offset to add
3463 * @shift: shift count to shift the result left
3465 * These values are estimates at best, so no need for locking.
3467 void get_avenrun(unsigned long *loads
, unsigned long offset
, int shift
)
3469 loads
[0] = (avenrun
[0] + offset
) << shift
;
3470 loads
[1] = (avenrun
[1] + offset
) << shift
;
3471 loads
[2] = (avenrun
[2] + offset
) << shift
;
3475 * calc_load - update the avenrun load estimates 10 ticks after the
3476 * CPUs have updated calc_load_tasks.
3478 void calc_global_load(unsigned long ticks
)
3482 calc_global_nohz(ticks
);
3484 if (time_before(jiffies
, calc_load_update
+ 10))
3487 active
= atomic_long_read(&calc_load_tasks
);
3488 active
= active
> 0 ? active
* FIXED_1
: 0;
3490 avenrun
[0] = calc_load(avenrun
[0], EXP_1
, active
);
3491 avenrun
[1] = calc_load(avenrun
[1], EXP_5
, active
);
3492 avenrun
[2] = calc_load(avenrun
[2], EXP_15
, active
);
3494 calc_load_update
+= LOAD_FREQ
;
3498 * Called from update_cpu_load() to periodically update this CPU's
3501 static void calc_load_account_active(struct rq
*this_rq
)
3505 if (time_before(jiffies
, this_rq
->calc_load_update
))
3508 delta
= calc_load_fold_active(this_rq
);
3509 delta
+= calc_load_fold_idle();
3511 atomic_long_add(delta
, &calc_load_tasks
);
3513 this_rq
->calc_load_update
+= LOAD_FREQ
;
3517 * The exact cpuload at various idx values, calculated at every tick would be
3518 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
3520 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
3521 * on nth tick when cpu may be busy, then we have:
3522 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
3523 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
3525 * decay_load_missed() below does efficient calculation of
3526 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
3527 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
3529 * The calculation is approximated on a 128 point scale.
3530 * degrade_zero_ticks is the number of ticks after which load at any
3531 * particular idx is approximated to be zero.
3532 * degrade_factor is a precomputed table, a row for each load idx.
3533 * Each column corresponds to degradation factor for a power of two ticks,
3534 * based on 128 point scale.
3536 * row 2, col 3 (=12) says that the degradation at load idx 2 after
3537 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
3539 * With this power of 2 load factors, we can degrade the load n times
3540 * by looking at 1 bits in n and doing as many mult/shift instead of
3541 * n mult/shifts needed by the exact degradation.
3543 #define DEGRADE_SHIFT 7
3544 static const unsigned char
3545 degrade_zero_ticks
[CPU_LOAD_IDX_MAX
] = {0, 8, 32, 64, 128};
3546 static const unsigned char
3547 degrade_factor
[CPU_LOAD_IDX_MAX
][DEGRADE_SHIFT
+ 1] = {
3548 {0, 0, 0, 0, 0, 0, 0, 0},
3549 {64, 32, 8, 0, 0, 0, 0, 0},
3550 {96, 72, 40, 12, 1, 0, 0},
3551 {112, 98, 75, 43, 15, 1, 0},
3552 {120, 112, 98, 76, 45, 16, 2} };
3555 * Update cpu_load for any missed ticks, due to tickless idle. The backlog
3556 * would be when CPU is idle and so we just decay the old load without
3557 * adding any new load.
3559 static unsigned long
3560 decay_load_missed(unsigned long load
, unsigned long missed_updates
, int idx
)
3564 if (!missed_updates
)
3567 if (missed_updates
>= degrade_zero_ticks
[idx
])
3571 return load
>> missed_updates
;
3573 while (missed_updates
) {
3574 if (missed_updates
% 2)
3575 load
= (load
* degrade_factor
[idx
][j
]) >> DEGRADE_SHIFT
;
3577 missed_updates
>>= 1;
3584 * Update rq->cpu_load[] statistics. This function is usually called every
3585 * scheduler tick (TICK_NSEC). With tickless idle this will not be called
3586 * every tick. We fix it up based on jiffies.
3588 static void update_cpu_load(struct rq
*this_rq
)
3590 unsigned long this_load
= this_rq
->load
.weight
;
3591 unsigned long curr_jiffies
= jiffies
;
3592 unsigned long pending_updates
;
3595 this_rq
->nr_load_updates
++;
3597 /* Avoid repeated calls on same jiffy, when moving in and out of idle */
3598 if (curr_jiffies
== this_rq
->last_load_update_tick
)
3601 pending_updates
= curr_jiffies
- this_rq
->last_load_update_tick
;
3602 this_rq
->last_load_update_tick
= curr_jiffies
;
3604 /* Update our load: */
3605 this_rq
->cpu_load
[0] = this_load
; /* Fasttrack for idx 0 */
3606 for (i
= 1, scale
= 2; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
3607 unsigned long old_load
, new_load
;
3609 /* scale is effectively 1 << i now, and >> i divides by scale */
3611 old_load
= this_rq
->cpu_load
[i
];
3612 old_load
= decay_load_missed(old_load
, pending_updates
- 1, i
);
3613 new_load
= this_load
;
3615 * Round up the averaging division if load is increasing. This
3616 * prevents us from getting stuck on 9 if the load is 10, for
3619 if (new_load
> old_load
)
3620 new_load
+= scale
- 1;
3622 this_rq
->cpu_load
[i
] = (old_load
* (scale
- 1) + new_load
) >> i
;
3625 sched_avg_update(this_rq
);
3628 static void update_cpu_load_active(struct rq
*this_rq
)
3630 update_cpu_load(this_rq
);
3632 calc_load_account_active(this_rq
);
3638 * sched_exec - execve() is a valuable balancing opportunity, because at
3639 * this point the task has the smallest effective memory and cache footprint.
3641 void sched_exec(void)
3643 struct task_struct
*p
= current
;
3644 unsigned long flags
;
3647 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
3648 dest_cpu
= p
->sched_class
->select_task_rq(p
, SD_BALANCE_EXEC
, 0);
3649 if (dest_cpu
== smp_processor_id())
3652 if (likely(cpu_active(dest_cpu
))) {
3653 struct migration_arg arg
= { p
, dest_cpu
};
3655 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
3656 stop_one_cpu(task_cpu(p
), migration_cpu_stop
, &arg
);
3660 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
3665 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
3667 EXPORT_PER_CPU_SYMBOL(kstat
);
3670 * Return any ns on the sched_clock that have not yet been accounted in
3671 * @p in case that task is currently running.
3673 * Called with task_rq_lock() held on @rq.
3675 static u64
do_task_delta_exec(struct task_struct
*p
, struct rq
*rq
)
3679 if (task_current(rq
, p
)) {
3680 update_rq_clock(rq
);
3681 ns
= rq
->clock_task
- p
->se
.exec_start
;
3689 unsigned long long task_delta_exec(struct task_struct
*p
)
3691 unsigned long flags
;
3695 rq
= task_rq_lock(p
, &flags
);
3696 ns
= do_task_delta_exec(p
, rq
);
3697 task_rq_unlock(rq
, p
, &flags
);
3703 * Return accounted runtime for the task.
3704 * In case the task is currently running, return the runtime plus current's
3705 * pending runtime that have not been accounted yet.
3707 unsigned long long task_sched_runtime(struct task_struct
*p
)
3709 unsigned long flags
;
3713 rq
= task_rq_lock(p
, &flags
);
3714 ns
= p
->se
.sum_exec_runtime
+ do_task_delta_exec(p
, rq
);
3715 task_rq_unlock(rq
, p
, &flags
);
3721 * Return sum_exec_runtime for the thread group.
3722 * In case the task is currently running, return the sum plus current's
3723 * pending runtime that have not been accounted yet.
3725 * Note that the thread group might have other running tasks as well,
3726 * so the return value not includes other pending runtime that other
3727 * running tasks might have.
3729 unsigned long long thread_group_sched_runtime(struct task_struct
*p
)
3731 struct task_cputime totals
;
3732 unsigned long flags
;
3736 rq
= task_rq_lock(p
, &flags
);
3737 thread_group_cputime(p
, &totals
);
3738 ns
= totals
.sum_exec_runtime
+ do_task_delta_exec(p
, rq
);
3739 task_rq_unlock(rq
, p
, &flags
);
3745 * Account user cpu time to a process.
3746 * @p: the process that the cpu time gets accounted to
3747 * @cputime: the cpu time spent in user space since the last update
3748 * @cputime_scaled: cputime scaled by cpu frequency
3750 void account_user_time(struct task_struct
*p
, cputime_t cputime
,
3751 cputime_t cputime_scaled
)
3753 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3756 /* Add user time to process. */
3757 p
->utime
= cputime_add(p
->utime
, cputime
);
3758 p
->utimescaled
= cputime_add(p
->utimescaled
, cputime_scaled
);
3759 account_group_user_time(p
, cputime
);
3761 /* Add user time to cpustat. */
3762 tmp
= cputime_to_cputime64(cputime
);
3763 if (TASK_NICE(p
) > 0)
3764 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3766 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3768 cpuacct_update_stats(p
, CPUACCT_STAT_USER
, cputime
);
3769 /* Account for user time used */
3770 acct_update_integrals(p
);
3774 * Account guest cpu time to a process.
3775 * @p: the process that the cpu time gets accounted to
3776 * @cputime: the cpu time spent in virtual machine since the last update
3777 * @cputime_scaled: cputime scaled by cpu frequency
3779 static void account_guest_time(struct task_struct
*p
, cputime_t cputime
,
3780 cputime_t cputime_scaled
)
3783 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3785 tmp
= cputime_to_cputime64(cputime
);
3787 /* Add guest time to process. */
3788 p
->utime
= cputime_add(p
->utime
, cputime
);
3789 p
->utimescaled
= cputime_add(p
->utimescaled
, cputime_scaled
);
3790 account_group_user_time(p
, cputime
);
3791 p
->gtime
= cputime_add(p
->gtime
, cputime
);
3793 /* Add guest time to cpustat. */
3794 if (TASK_NICE(p
) > 0) {
3795 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3796 cpustat
->guest_nice
= cputime64_add(cpustat
->guest_nice
, tmp
);
3798 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3799 cpustat
->guest
= cputime64_add(cpustat
->guest
, tmp
);
3804 * Account system cpu time to a process and desired cpustat field
3805 * @p: the process that the cpu time gets accounted to
3806 * @cputime: the cpu time spent in kernel space since the last update
3807 * @cputime_scaled: cputime scaled by cpu frequency
3808 * @target_cputime64: pointer to cpustat field that has to be updated
3811 void __account_system_time(struct task_struct
*p
, cputime_t cputime
,
3812 cputime_t cputime_scaled
, cputime64_t
*target_cputime64
)
3814 cputime64_t tmp
= cputime_to_cputime64(cputime
);
3816 /* Add system time to process. */
3817 p
->stime
= cputime_add(p
->stime
, cputime
);
3818 p
->stimescaled
= cputime_add(p
->stimescaled
, cputime_scaled
);
3819 account_group_system_time(p
, cputime
);
3821 /* Add system time to cpustat. */
3822 *target_cputime64
= cputime64_add(*target_cputime64
, tmp
);
3823 cpuacct_update_stats(p
, CPUACCT_STAT_SYSTEM
, cputime
);
3825 /* Account for system time used */
3826 acct_update_integrals(p
);
3830 * Account system cpu time to a process.
3831 * @p: the process that the cpu time gets accounted to
3832 * @hardirq_offset: the offset to subtract from hardirq_count()
3833 * @cputime: the cpu time spent in kernel space since the last update
3834 * @cputime_scaled: cputime scaled by cpu frequency
3836 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
3837 cputime_t cputime
, cputime_t cputime_scaled
)
3839 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3840 cputime64_t
*target_cputime64
;
3842 if ((p
->flags
& PF_VCPU
) && (irq_count() - hardirq_offset
== 0)) {
3843 account_guest_time(p
, cputime
, cputime_scaled
);
3847 if (hardirq_count() - hardirq_offset
)
3848 target_cputime64
= &cpustat
->irq
;
3849 else if (in_serving_softirq())
3850 target_cputime64
= &cpustat
->softirq
;
3852 target_cputime64
= &cpustat
->system
;
3854 __account_system_time(p
, cputime
, cputime_scaled
, target_cputime64
);
3858 * Account for involuntary wait time.
3859 * @cputime: the cpu time spent in involuntary wait
3861 void account_steal_time(cputime_t cputime
)
3863 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3864 cputime64_t cputime64
= cputime_to_cputime64(cputime
);
3866 cpustat
->steal
= cputime64_add(cpustat
->steal
, cputime64
);
3870 * Account for idle time.
3871 * @cputime: the cpu time spent in idle wait
3873 void account_idle_time(cputime_t cputime
)
3875 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3876 cputime64_t cputime64
= cputime_to_cputime64(cputime
);
3877 struct rq
*rq
= this_rq();
3879 if (atomic_read(&rq
->nr_iowait
) > 0)
3880 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, cputime64
);
3882 cpustat
->idle
= cputime64_add(cpustat
->idle
, cputime64
);
3885 static __always_inline
bool steal_account_process_tick(void)
3887 #ifdef CONFIG_PARAVIRT
3888 if (static_branch(¶virt_steal_enabled
)) {
3891 steal
= paravirt_steal_clock(smp_processor_id());
3892 steal
-= this_rq()->prev_steal_time
;
3894 st
= steal_ticks(steal
);
3895 this_rq()->prev_steal_time
+= st
* TICK_NSEC
;
3897 account_steal_time(st
);
3904 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
3906 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
3908 * Account a tick to a process and cpustat
3909 * @p: the process that the cpu time gets accounted to
3910 * @user_tick: is the tick from userspace
3911 * @rq: the pointer to rq
3913 * Tick demultiplexing follows the order
3914 * - pending hardirq update
3915 * - pending softirq update
3919 * - check for guest_time
3920 * - else account as system_time
3922 * Check for hardirq is done both for system and user time as there is
3923 * no timer going off while we are on hardirq and hence we may never get an
3924 * opportunity to update it solely in system time.
3925 * p->stime and friends are only updated on system time and not on irq
3926 * softirq as those do not count in task exec_runtime any more.
3928 static void irqtime_account_process_tick(struct task_struct
*p
, int user_tick
,
3931 cputime_t one_jiffy_scaled
= cputime_to_scaled(cputime_one_jiffy
);
3932 cputime64_t tmp
= cputime_to_cputime64(cputime_one_jiffy
);
3933 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3935 if (steal_account_process_tick())
3938 if (irqtime_account_hi_update()) {
3939 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
3940 } else if (irqtime_account_si_update()) {
3941 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
3942 } else if (this_cpu_ksoftirqd() == p
) {
3944 * ksoftirqd time do not get accounted in cpu_softirq_time.
3945 * So, we have to handle it separately here.
3946 * Also, p->stime needs to be updated for ksoftirqd.
3948 __account_system_time(p
, cputime_one_jiffy
, one_jiffy_scaled
,
3950 } else if (user_tick
) {
3951 account_user_time(p
, cputime_one_jiffy
, one_jiffy_scaled
);
3952 } else if (p
== rq
->idle
) {
3953 account_idle_time(cputime_one_jiffy
);
3954 } else if (p
->flags
& PF_VCPU
) { /* System time or guest time */
3955 account_guest_time(p
, cputime_one_jiffy
, one_jiffy_scaled
);
3957 __account_system_time(p
, cputime_one_jiffy
, one_jiffy_scaled
,
3962 static void irqtime_account_idle_ticks(int ticks
)
3965 struct rq
*rq
= this_rq();
3967 for (i
= 0; i
< ticks
; i
++)
3968 irqtime_account_process_tick(current
, 0, rq
);
3970 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
3971 static void irqtime_account_idle_ticks(int ticks
) {}
3972 static void irqtime_account_process_tick(struct task_struct
*p
, int user_tick
,
3974 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
3977 * Account a single tick of cpu time.
3978 * @p: the process that the cpu time gets accounted to
3979 * @user_tick: indicates if the tick is a user or a system tick
3981 void account_process_tick(struct task_struct
*p
, int user_tick
)
3983 cputime_t one_jiffy_scaled
= cputime_to_scaled(cputime_one_jiffy
);
3984 struct rq
*rq
= this_rq();
3986 if (sched_clock_irqtime
) {
3987 irqtime_account_process_tick(p
, user_tick
, rq
);
3991 if (steal_account_process_tick())
3995 account_user_time(p
, cputime_one_jiffy
, one_jiffy_scaled
);
3996 else if ((p
!= rq
->idle
) || (irq_count() != HARDIRQ_OFFSET
))
3997 account_system_time(p
, HARDIRQ_OFFSET
, cputime_one_jiffy
,
4000 account_idle_time(cputime_one_jiffy
);
4004 * Account multiple ticks of steal time.
4005 * @p: the process from which the cpu time has been stolen
4006 * @ticks: number of stolen ticks
4008 void account_steal_ticks(unsigned long ticks
)
4010 account_steal_time(jiffies_to_cputime(ticks
));
4014 * Account multiple ticks of idle time.
4015 * @ticks: number of stolen ticks
4017 void account_idle_ticks(unsigned long ticks
)
4020 if (sched_clock_irqtime
) {
4021 irqtime_account_idle_ticks(ticks
);
4025 account_idle_time(jiffies_to_cputime(ticks
));
4031 * Use precise platform statistics if available:
4033 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
4034 void task_times(struct task_struct
*p
, cputime_t
*ut
, cputime_t
*st
)
4040 void thread_group_times(struct task_struct
*p
, cputime_t
*ut
, cputime_t
*st
)
4042 struct task_cputime cputime
;
4044 thread_group_cputime(p
, &cputime
);
4046 *ut
= cputime
.utime
;
4047 *st
= cputime
.stime
;
4051 #ifndef nsecs_to_cputime
4052 # define nsecs_to_cputime(__nsecs) nsecs_to_jiffies(__nsecs)
4055 void task_times(struct task_struct
*p
, cputime_t
*ut
, cputime_t
*st
)
4057 cputime_t rtime
, utime
= p
->utime
, total
= cputime_add(utime
, p
->stime
);
4060 * Use CFS's precise accounting:
4062 rtime
= nsecs_to_cputime(p
->se
.sum_exec_runtime
);
4068 do_div(temp
, total
);
4069 utime
= (cputime_t
)temp
;
4074 * Compare with previous values, to keep monotonicity:
4076 p
->prev_utime
= max(p
->prev_utime
, utime
);
4077 p
->prev_stime
= max(p
->prev_stime
, cputime_sub(rtime
, p
->prev_utime
));
4079 *ut
= p
->prev_utime
;
4080 *st
= p
->prev_stime
;
4084 * Must be called with siglock held.
4086 void thread_group_times(struct task_struct
*p
, cputime_t
*ut
, cputime_t
*st
)
4088 struct signal_struct
*sig
= p
->signal
;
4089 struct task_cputime cputime
;
4090 cputime_t rtime
, utime
, total
;
4092 thread_group_cputime(p
, &cputime
);
4094 total
= cputime_add(cputime
.utime
, cputime
.stime
);
4095 rtime
= nsecs_to_cputime(cputime
.sum_exec_runtime
);
4100 temp
*= cputime
.utime
;
4101 do_div(temp
, total
);
4102 utime
= (cputime_t
)temp
;
4106 sig
->prev_utime
= max(sig
->prev_utime
, utime
);
4107 sig
->prev_stime
= max(sig
->prev_stime
,
4108 cputime_sub(rtime
, sig
->prev_utime
));
4110 *ut
= sig
->prev_utime
;
4111 *st
= sig
->prev_stime
;
4116 * This function gets called by the timer code, with HZ frequency.
4117 * We call it with interrupts disabled.
4119 void scheduler_tick(void)
4121 int cpu
= smp_processor_id();
4122 struct rq
*rq
= cpu_rq(cpu
);
4123 struct task_struct
*curr
= rq
->curr
;
4127 raw_spin_lock(&rq
->lock
);
4128 update_rq_clock(rq
);
4129 update_cpu_load_active(rq
);
4130 curr
->sched_class
->task_tick(rq
, curr
, 0);
4131 raw_spin_unlock(&rq
->lock
);
4133 perf_event_task_tick();
4136 rq
->idle_at_tick
= idle_cpu(cpu
);
4137 trigger_load_balance(rq
, cpu
);
4141 notrace
unsigned long get_parent_ip(unsigned long addr
)
4143 if (in_lock_functions(addr
)) {
4144 addr
= CALLER_ADDR2
;
4145 if (in_lock_functions(addr
))
4146 addr
= CALLER_ADDR3
;
4151 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
4152 defined(CONFIG_PREEMPT_TRACER))
4154 void __kprobes
add_preempt_count(int val
)
4156 #ifdef CONFIG_DEBUG_PREEMPT
4160 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
4163 preempt_count() += val
;
4164 #ifdef CONFIG_DEBUG_PREEMPT
4166 * Spinlock count overflowing soon?
4168 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
4171 if (preempt_count() == val
)
4172 trace_preempt_off(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
4174 EXPORT_SYMBOL(add_preempt_count
);
4176 void __kprobes
sub_preempt_count(int val
)
4178 #ifdef CONFIG_DEBUG_PREEMPT
4182 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
4185 * Is the spinlock portion underflowing?
4187 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
4188 !(preempt_count() & PREEMPT_MASK
)))
4192 if (preempt_count() == val
)
4193 trace_preempt_on(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
4194 preempt_count() -= val
;
4196 EXPORT_SYMBOL(sub_preempt_count
);
4201 * Print scheduling while atomic bug:
4203 static noinline
void __schedule_bug(struct task_struct
*prev
)
4205 struct pt_regs
*regs
= get_irq_regs();
4207 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
4208 prev
->comm
, prev
->pid
, preempt_count());
4210 debug_show_held_locks(prev
);
4212 if (irqs_disabled())
4213 print_irqtrace_events(prev
);
4222 * Various schedule()-time debugging checks and statistics:
4224 static inline void schedule_debug(struct task_struct
*prev
)
4227 * Test if we are atomic. Since do_exit() needs to call into
4228 * schedule() atomically, we ignore that path for now.
4229 * Otherwise, whine if we are scheduling when we should not be.
4231 if (unlikely(in_atomic_preempt_off() && !prev
->exit_state
))
4232 __schedule_bug(prev
);
4234 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
4236 schedstat_inc(this_rq(), sched_count
);
4239 static void put_prev_task(struct rq
*rq
, struct task_struct
*prev
)
4241 if (prev
->on_rq
|| rq
->skip_clock_update
< 0)
4242 update_rq_clock(rq
);
4243 prev
->sched_class
->put_prev_task(rq
, prev
);
4247 * Pick up the highest-prio task:
4249 static inline struct task_struct
*
4250 pick_next_task(struct rq
*rq
)
4252 const struct sched_class
*class;
4253 struct task_struct
*p
;
4256 * Optimization: we know that if all tasks are in
4257 * the fair class we can call that function directly:
4259 if (likely(rq
->nr_running
== rq
->cfs
.h_nr_running
)) {
4260 p
= fair_sched_class
.pick_next_task(rq
);
4265 for_each_class(class) {
4266 p
= class->pick_next_task(rq
);
4271 BUG(); /* the idle class will always have a runnable task */
4275 * schedule() is the main scheduler function.
4277 asmlinkage
void __sched
schedule(void)
4279 struct task_struct
*prev
, *next
;
4280 unsigned long *switch_count
;
4286 cpu
= smp_processor_id();
4288 rcu_note_context_switch(cpu
);
4291 schedule_debug(prev
);
4293 if (sched_feat(HRTICK
))
4296 raw_spin_lock_irq(&rq
->lock
);
4298 switch_count
= &prev
->nivcsw
;
4299 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
4300 if (unlikely(signal_pending_state(prev
->state
, prev
))) {
4301 prev
->state
= TASK_RUNNING
;
4303 deactivate_task(rq
, prev
, DEQUEUE_SLEEP
);
4307 * If a worker went to sleep, notify and ask workqueue
4308 * whether it wants to wake up a task to maintain
4311 if (prev
->flags
& PF_WQ_WORKER
) {
4312 struct task_struct
*to_wakeup
;
4314 to_wakeup
= wq_worker_sleeping(prev
, cpu
);
4316 try_to_wake_up_local(to_wakeup
);
4320 * If we are going to sleep and we have plugged IO
4321 * queued, make sure to submit it to avoid deadlocks.
4323 if (blk_needs_flush_plug(prev
)) {
4324 raw_spin_unlock(&rq
->lock
);
4325 blk_schedule_flush_plug(prev
);
4326 raw_spin_lock(&rq
->lock
);
4329 switch_count
= &prev
->nvcsw
;
4332 pre_schedule(rq
, prev
);
4334 if (unlikely(!rq
->nr_running
))
4335 idle_balance(cpu
, rq
);
4337 put_prev_task(rq
, prev
);
4338 next
= pick_next_task(rq
);
4339 clear_tsk_need_resched(prev
);
4340 rq
->skip_clock_update
= 0;
4342 if (likely(prev
!= next
)) {
4347 context_switch(rq
, prev
, next
); /* unlocks the rq */
4349 * The context switch have flipped the stack from under us
4350 * and restored the local variables which were saved when
4351 * this task called schedule() in the past. prev == current
4352 * is still correct, but it can be moved to another cpu/rq.
4354 cpu
= smp_processor_id();
4357 raw_spin_unlock_irq(&rq
->lock
);
4361 preempt_enable_no_resched();
4365 EXPORT_SYMBOL(schedule
);
4367 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
4369 static inline bool owner_running(struct mutex
*lock
, struct task_struct
*owner
)
4371 if (lock
->owner
!= owner
)
4375 * Ensure we emit the owner->on_cpu, dereference _after_ checking
4376 * lock->owner still matches owner, if that fails, owner might
4377 * point to free()d memory, if it still matches, the rcu_read_lock()
4378 * ensures the memory stays valid.
4382 return owner
->on_cpu
;
4386 * Look out! "owner" is an entirely speculative pointer
4387 * access and not reliable.
4389 int mutex_spin_on_owner(struct mutex
*lock
, struct task_struct
*owner
)
4391 if (!sched_feat(OWNER_SPIN
))
4395 while (owner_running(lock
, owner
)) {
4399 arch_mutex_cpu_relax();
4404 * We break out the loop above on need_resched() and when the
4405 * owner changed, which is a sign for heavy contention. Return
4406 * success only when lock->owner is NULL.
4408 return lock
->owner
== NULL
;
4412 #ifdef CONFIG_PREEMPT
4414 * this is the entry point to schedule() from in-kernel preemption
4415 * off of preempt_enable. Kernel preemptions off return from interrupt
4416 * occur there and call schedule directly.
4418 asmlinkage
void __sched notrace
preempt_schedule(void)
4420 struct thread_info
*ti
= current_thread_info();
4423 * If there is a non-zero preempt_count or interrupts are disabled,
4424 * we do not want to preempt the current task. Just return..
4426 if (likely(ti
->preempt_count
|| irqs_disabled()))
4430 add_preempt_count_notrace(PREEMPT_ACTIVE
);
4432 sub_preempt_count_notrace(PREEMPT_ACTIVE
);
4435 * Check again in case we missed a preemption opportunity
4436 * between schedule and now.
4439 } while (need_resched());
4441 EXPORT_SYMBOL(preempt_schedule
);
4444 * this is the entry point to schedule() from kernel preemption
4445 * off of irq context.
4446 * Note, that this is called and return with irqs disabled. This will
4447 * protect us against recursive calling from irq.
4449 asmlinkage
void __sched
preempt_schedule_irq(void)
4451 struct thread_info
*ti
= current_thread_info();
4453 /* Catch callers which need to be fixed */
4454 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
4457 add_preempt_count(PREEMPT_ACTIVE
);
4460 local_irq_disable();
4461 sub_preempt_count(PREEMPT_ACTIVE
);
4464 * Check again in case we missed a preemption opportunity
4465 * between schedule and now.
4468 } while (need_resched());
4471 #endif /* CONFIG_PREEMPT */
4473 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int wake_flags
,
4476 return try_to_wake_up(curr
->private, mode
, wake_flags
);
4478 EXPORT_SYMBOL(default_wake_function
);
4481 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
4482 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
4483 * number) then we wake all the non-exclusive tasks and one exclusive task.
4485 * There are circumstances in which we can try to wake a task which has already
4486 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
4487 * zero in this (rare) case, and we handle it by continuing to scan the queue.
4489 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
4490 int nr_exclusive
, int wake_flags
, void *key
)
4492 wait_queue_t
*curr
, *next
;
4494 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
4495 unsigned flags
= curr
->flags
;
4497 if (curr
->func(curr
, mode
, wake_flags
, key
) &&
4498 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
4504 * __wake_up - wake up threads blocked on a waitqueue.
4506 * @mode: which threads
4507 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4508 * @key: is directly passed to the wakeup function
4510 * It may be assumed that this function implies a write memory barrier before
4511 * changing the task state if and only if any tasks are woken up.
4513 void __wake_up(wait_queue_head_t
*q
, unsigned int mode
,
4514 int nr_exclusive
, void *key
)
4516 unsigned long flags
;
4518 spin_lock_irqsave(&q
->lock
, flags
);
4519 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
4520 spin_unlock_irqrestore(&q
->lock
, flags
);
4522 EXPORT_SYMBOL(__wake_up
);
4525 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
4527 void __wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
4529 __wake_up_common(q
, mode
, 1, 0, NULL
);
4531 EXPORT_SYMBOL_GPL(__wake_up_locked
);
4533 void __wake_up_locked_key(wait_queue_head_t
*q
, unsigned int mode
, void *key
)
4535 __wake_up_common(q
, mode
, 1, 0, key
);
4537 EXPORT_SYMBOL_GPL(__wake_up_locked_key
);
4540 * __wake_up_sync_key - wake up threads blocked on a waitqueue.
4542 * @mode: which threads
4543 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4544 * @key: opaque value to be passed to wakeup targets
4546 * The sync wakeup differs that the waker knows that it will schedule
4547 * away soon, so while the target thread will be woken up, it will not
4548 * be migrated to another CPU - ie. the two threads are 'synchronized'
4549 * with each other. This can prevent needless bouncing between CPUs.
4551 * On UP it can prevent extra preemption.
4553 * It may be assumed that this function implies a write memory barrier before
4554 * changing the task state if and only if any tasks are woken up.
4556 void __wake_up_sync_key(wait_queue_head_t
*q
, unsigned int mode
,
4557 int nr_exclusive
, void *key
)
4559 unsigned long flags
;
4560 int wake_flags
= WF_SYNC
;
4565 if (unlikely(!nr_exclusive
))
4568 spin_lock_irqsave(&q
->lock
, flags
);
4569 __wake_up_common(q
, mode
, nr_exclusive
, wake_flags
, key
);
4570 spin_unlock_irqrestore(&q
->lock
, flags
);
4572 EXPORT_SYMBOL_GPL(__wake_up_sync_key
);
4575 * __wake_up_sync - see __wake_up_sync_key()
4577 void __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
4579 __wake_up_sync_key(q
, mode
, nr_exclusive
, NULL
);
4581 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
4584 * complete: - signals a single thread waiting on this completion
4585 * @x: holds the state of this particular completion
4587 * This will wake up a single thread waiting on this completion. Threads will be
4588 * awakened in the same order in which they were queued.
4590 * See also complete_all(), wait_for_completion() and related routines.
4592 * It may be assumed that this function implies a write memory barrier before
4593 * changing the task state if and only if any tasks are woken up.
4595 void complete(struct completion
*x
)
4597 unsigned long flags
;
4599 spin_lock_irqsave(&x
->wait
.lock
, flags
);
4601 __wake_up_common(&x
->wait
, TASK_NORMAL
, 1, 0, NULL
);
4602 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
4604 EXPORT_SYMBOL(complete
);
4607 * complete_all: - signals all threads waiting on this completion
4608 * @x: holds the state of this particular completion
4610 * This will wake up all threads waiting on this particular completion event.
4612 * It may be assumed that this function implies a write memory barrier before
4613 * changing the task state if and only if any tasks are woken up.
4615 void complete_all(struct completion
*x
)
4617 unsigned long flags
;
4619 spin_lock_irqsave(&x
->wait
.lock
, flags
);
4620 x
->done
+= UINT_MAX
/2;
4621 __wake_up_common(&x
->wait
, TASK_NORMAL
, 0, 0, NULL
);
4622 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
4624 EXPORT_SYMBOL(complete_all
);
4626 static inline long __sched
4627 do_wait_for_common(struct completion
*x
, long timeout
, int state
)
4630 DECLARE_WAITQUEUE(wait
, current
);
4632 __add_wait_queue_tail_exclusive(&x
->wait
, &wait
);
4634 if (signal_pending_state(state
, current
)) {
4635 timeout
= -ERESTARTSYS
;
4638 __set_current_state(state
);
4639 spin_unlock_irq(&x
->wait
.lock
);
4640 timeout
= schedule_timeout(timeout
);
4641 spin_lock_irq(&x
->wait
.lock
);
4642 } while (!x
->done
&& timeout
);
4643 __remove_wait_queue(&x
->wait
, &wait
);
4648 return timeout
?: 1;
4652 wait_for_common(struct completion
*x
, long timeout
, int state
)
4656 spin_lock_irq(&x
->wait
.lock
);
4657 timeout
= do_wait_for_common(x
, timeout
, state
);
4658 spin_unlock_irq(&x
->wait
.lock
);
4663 * wait_for_completion: - waits for completion of a task
4664 * @x: holds the state of this particular completion
4666 * This waits to be signaled for completion of a specific task. It is NOT
4667 * interruptible and there is no timeout.
4669 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
4670 * and interrupt capability. Also see complete().
4672 void __sched
wait_for_completion(struct completion
*x
)
4674 wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
4676 EXPORT_SYMBOL(wait_for_completion
);
4679 * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
4680 * @x: holds the state of this particular completion
4681 * @timeout: timeout value in jiffies
4683 * This waits for either a completion of a specific task to be signaled or for a
4684 * specified timeout to expire. The timeout is in jiffies. It is not
4687 unsigned long __sched
4688 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
4690 return wait_for_common(x
, timeout
, TASK_UNINTERRUPTIBLE
);
4692 EXPORT_SYMBOL(wait_for_completion_timeout
);
4695 * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
4696 * @x: holds the state of this particular completion
4698 * This waits for completion of a specific task to be signaled. It is
4701 int __sched
wait_for_completion_interruptible(struct completion
*x
)
4703 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_INTERRUPTIBLE
);
4704 if (t
== -ERESTARTSYS
)
4708 EXPORT_SYMBOL(wait_for_completion_interruptible
);
4711 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
4712 * @x: holds the state of this particular completion
4713 * @timeout: timeout value in jiffies
4715 * This waits for either a completion of a specific task to be signaled or for a
4716 * specified timeout to expire. It is interruptible. The timeout is in jiffies.
4719 wait_for_completion_interruptible_timeout(struct completion
*x
,
4720 unsigned long timeout
)
4722 return wait_for_common(x
, timeout
, TASK_INTERRUPTIBLE
);
4724 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
4727 * wait_for_completion_killable: - waits for completion of a task (killable)
4728 * @x: holds the state of this particular completion
4730 * This waits to be signaled for completion of a specific task. It can be
4731 * interrupted by a kill signal.
4733 int __sched
wait_for_completion_killable(struct completion
*x
)
4735 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_KILLABLE
);
4736 if (t
== -ERESTARTSYS
)
4740 EXPORT_SYMBOL(wait_for_completion_killable
);
4743 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
4744 * @x: holds the state of this particular completion
4745 * @timeout: timeout value in jiffies
4747 * This waits for either a completion of a specific task to be
4748 * signaled or for a specified timeout to expire. It can be
4749 * interrupted by a kill signal. The timeout is in jiffies.
4752 wait_for_completion_killable_timeout(struct completion
*x
,
4753 unsigned long timeout
)
4755 return wait_for_common(x
, timeout
, TASK_KILLABLE
);
4757 EXPORT_SYMBOL(wait_for_completion_killable_timeout
);
4760 * try_wait_for_completion - try to decrement a completion without blocking
4761 * @x: completion structure
4763 * Returns: 0 if a decrement cannot be done without blocking
4764 * 1 if a decrement succeeded.
4766 * If a completion is being used as a counting completion,
4767 * attempt to decrement the counter without blocking. This
4768 * enables us to avoid waiting if the resource the completion
4769 * is protecting is not available.
4771 bool try_wait_for_completion(struct completion
*x
)
4773 unsigned long flags
;
4776 spin_lock_irqsave(&x
->wait
.lock
, flags
);
4781 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
4784 EXPORT_SYMBOL(try_wait_for_completion
);
4787 * completion_done - Test to see if a completion has any waiters
4788 * @x: completion structure
4790 * Returns: 0 if there are waiters (wait_for_completion() in progress)
4791 * 1 if there are no waiters.
4794 bool completion_done(struct completion
*x
)
4796 unsigned long flags
;
4799 spin_lock_irqsave(&x
->wait
.lock
, flags
);
4802 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
4805 EXPORT_SYMBOL(completion_done
);
4808 sleep_on_common(wait_queue_head_t
*q
, int state
, long timeout
)
4810 unsigned long flags
;
4813 init_waitqueue_entry(&wait
, current
);
4815 __set_current_state(state
);
4817 spin_lock_irqsave(&q
->lock
, flags
);
4818 __add_wait_queue(q
, &wait
);
4819 spin_unlock(&q
->lock
);
4820 timeout
= schedule_timeout(timeout
);
4821 spin_lock_irq(&q
->lock
);
4822 __remove_wait_queue(q
, &wait
);
4823 spin_unlock_irqrestore(&q
->lock
, flags
);
4828 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
4830 sleep_on_common(q
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
4832 EXPORT_SYMBOL(interruptible_sleep_on
);
4835 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
4837 return sleep_on_common(q
, TASK_INTERRUPTIBLE
, timeout
);
4839 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
4841 void __sched
sleep_on(wait_queue_head_t
*q
)
4843 sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
4845 EXPORT_SYMBOL(sleep_on
);
4847 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
4849 return sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, timeout
);
4851 EXPORT_SYMBOL(sleep_on_timeout
);
4853 #ifdef CONFIG_RT_MUTEXES
4856 * rt_mutex_setprio - set the current priority of a task
4858 * @prio: prio value (kernel-internal form)
4860 * This function changes the 'effective' priority of a task. It does
4861 * not touch ->normal_prio like __setscheduler().
4863 * Used by the rt_mutex code to implement priority inheritance logic.
4865 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
4867 int oldprio
, on_rq
, running
;
4869 const struct sched_class
*prev_class
;
4871 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
4873 rq
= __task_rq_lock(p
);
4875 trace_sched_pi_setprio(p
, prio
);
4877 prev_class
= p
->sched_class
;
4879 running
= task_current(rq
, p
);
4881 dequeue_task(rq
, p
, 0);
4883 p
->sched_class
->put_prev_task(rq
, p
);
4886 p
->sched_class
= &rt_sched_class
;
4888 p
->sched_class
= &fair_sched_class
;
4893 p
->sched_class
->set_curr_task(rq
);
4895 enqueue_task(rq
, p
, oldprio
< prio
? ENQUEUE_HEAD
: 0);
4897 check_class_changed(rq
, p
, prev_class
, oldprio
);
4898 __task_rq_unlock(rq
);
4903 void set_user_nice(struct task_struct
*p
, long nice
)
4905 int old_prio
, delta
, on_rq
;
4906 unsigned long flags
;
4909 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
4912 * We have to be careful, if called from sys_setpriority(),
4913 * the task might be in the middle of scheduling on another CPU.
4915 rq
= task_rq_lock(p
, &flags
);
4917 * The RT priorities are set via sched_setscheduler(), but we still
4918 * allow the 'normal' nice value to be set - but as expected
4919 * it wont have any effect on scheduling until the task is
4920 * SCHED_FIFO/SCHED_RR:
4922 if (task_has_rt_policy(p
)) {
4923 p
->static_prio
= NICE_TO_PRIO(nice
);
4928 dequeue_task(rq
, p
, 0);
4930 p
->static_prio
= NICE_TO_PRIO(nice
);
4933 p
->prio
= effective_prio(p
);
4934 delta
= p
->prio
- old_prio
;
4937 enqueue_task(rq
, p
, 0);
4939 * If the task increased its priority or is running and
4940 * lowered its priority, then reschedule its CPU:
4942 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
4943 resched_task(rq
->curr
);
4946 task_rq_unlock(rq
, p
, &flags
);
4948 EXPORT_SYMBOL(set_user_nice
);
4951 * can_nice - check if a task can reduce its nice value
4955 int can_nice(const struct task_struct
*p
, const int nice
)
4957 /* convert nice value [19,-20] to rlimit style value [1,40] */
4958 int nice_rlim
= 20 - nice
;
4960 return (nice_rlim
<= task_rlimit(p
, RLIMIT_NICE
) ||
4961 capable(CAP_SYS_NICE
));
4964 #ifdef __ARCH_WANT_SYS_NICE
4967 * sys_nice - change the priority of the current process.
4968 * @increment: priority increment
4970 * sys_setpriority is a more generic, but much slower function that
4971 * does similar things.
4973 SYSCALL_DEFINE1(nice
, int, increment
)
4978 * Setpriority might change our priority at the same moment.
4979 * We don't have to worry. Conceptually one call occurs first
4980 * and we have a single winner.
4982 if (increment
< -40)
4987 nice
= TASK_NICE(current
) + increment
;
4993 if (increment
< 0 && !can_nice(current
, nice
))
4996 retval
= security_task_setnice(current
, nice
);
5000 set_user_nice(current
, nice
);
5007 * task_prio - return the priority value of a given task.
5008 * @p: the task in question.
5010 * This is the priority value as seen by users in /proc.
5011 * RT tasks are offset by -200. Normal tasks are centered
5012 * around 0, value goes from -16 to +15.
5014 int task_prio(const struct task_struct
*p
)
5016 return p
->prio
- MAX_RT_PRIO
;
5020 * task_nice - return the nice value of a given task.
5021 * @p: the task in question.
5023 int task_nice(const struct task_struct
*p
)
5025 return TASK_NICE(p
);
5027 EXPORT_SYMBOL(task_nice
);
5030 * idle_cpu - is a given cpu idle currently?
5031 * @cpu: the processor in question.
5033 int idle_cpu(int cpu
)
5035 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
5039 * idle_task - return the idle task for a given cpu.
5040 * @cpu: the processor in question.
5042 struct task_struct
*idle_task(int cpu
)
5044 return cpu_rq(cpu
)->idle
;
5048 * find_process_by_pid - find a process with a matching PID value.
5049 * @pid: the pid in question.
5051 static struct task_struct
*find_process_by_pid(pid_t pid
)
5053 return pid
? find_task_by_vpid(pid
) : current
;
5056 /* Actually do priority change: must hold rq lock. */
5058 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
5061 p
->rt_priority
= prio
;
5062 p
->normal_prio
= normal_prio(p
);
5063 /* we are holding p->pi_lock already */
5064 p
->prio
= rt_mutex_getprio(p
);
5065 if (rt_prio(p
->prio
))
5066 p
->sched_class
= &rt_sched_class
;
5068 p
->sched_class
= &fair_sched_class
;
5073 * check the target process has a UID that matches the current process's
5075 static bool check_same_owner(struct task_struct
*p
)
5077 const struct cred
*cred
= current_cred(), *pcred
;
5081 pcred
= __task_cred(p
);
5082 if (cred
->user
->user_ns
== pcred
->user
->user_ns
)
5083 match
= (cred
->euid
== pcred
->euid
||
5084 cred
->euid
== pcred
->uid
);
5091 static int __sched_setscheduler(struct task_struct
*p
, int policy
,
5092 const struct sched_param
*param
, bool user
)
5094 int retval
, oldprio
, oldpolicy
= -1, on_rq
, running
;
5095 unsigned long flags
;
5096 const struct sched_class
*prev_class
;
5100 /* may grab non-irq protected spin_locks */
5101 BUG_ON(in_interrupt());
5103 /* double check policy once rq lock held */
5105 reset_on_fork
= p
->sched_reset_on_fork
;
5106 policy
= oldpolicy
= p
->policy
;
5108 reset_on_fork
= !!(policy
& SCHED_RESET_ON_FORK
);
5109 policy
&= ~SCHED_RESET_ON_FORK
;
5111 if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
5112 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
5113 policy
!= SCHED_IDLE
)
5118 * Valid priorities for SCHED_FIFO and SCHED_RR are
5119 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
5120 * SCHED_BATCH and SCHED_IDLE is 0.
5122 if (param
->sched_priority
< 0 ||
5123 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
5124 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
5126 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
5130 * Allow unprivileged RT tasks to decrease priority:
5132 if (user
&& !capable(CAP_SYS_NICE
)) {
5133 if (rt_policy(policy
)) {
5134 unsigned long rlim_rtprio
=
5135 task_rlimit(p
, RLIMIT_RTPRIO
);
5137 /* can't set/change the rt policy */
5138 if (policy
!= p
->policy
&& !rlim_rtprio
)
5141 /* can't increase priority */
5142 if (param
->sched_priority
> p
->rt_priority
&&
5143 param
->sched_priority
> rlim_rtprio
)
5148 * Treat SCHED_IDLE as nice 20. Only allow a switch to
5149 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
5151 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
) {
5152 if (!can_nice(p
, TASK_NICE(p
)))
5156 /* can't change other user's priorities */
5157 if (!check_same_owner(p
))
5160 /* Normal users shall not reset the sched_reset_on_fork flag */
5161 if (p
->sched_reset_on_fork
&& !reset_on_fork
)
5166 retval
= security_task_setscheduler(p
);
5172 * make sure no PI-waiters arrive (or leave) while we are
5173 * changing the priority of the task:
5175 * To be able to change p->policy safely, the appropriate
5176 * runqueue lock must be held.
5178 rq
= task_rq_lock(p
, &flags
);
5181 * Changing the policy of the stop threads its a very bad idea
5183 if (p
== rq
->stop
) {
5184 task_rq_unlock(rq
, p
, &flags
);
5189 * If not changing anything there's no need to proceed further:
5191 if (unlikely(policy
== p
->policy
&& (!rt_policy(policy
) ||
5192 param
->sched_priority
== p
->rt_priority
))) {
5194 __task_rq_unlock(rq
);
5195 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
5199 #ifdef CONFIG_RT_GROUP_SCHED
5202 * Do not allow realtime tasks into groups that have no runtime
5205 if (rt_bandwidth_enabled() && rt_policy(policy
) &&
5206 task_group(p
)->rt_bandwidth
.rt_runtime
== 0 &&
5207 !task_group_is_autogroup(task_group(p
))) {
5208 task_rq_unlock(rq
, p
, &flags
);
5214 /* recheck policy now with rq lock held */
5215 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
5216 policy
= oldpolicy
= -1;
5217 task_rq_unlock(rq
, p
, &flags
);
5221 running
= task_current(rq
, p
);
5223 deactivate_task(rq
, p
, 0);
5225 p
->sched_class
->put_prev_task(rq
, p
);
5227 p
->sched_reset_on_fork
= reset_on_fork
;
5230 prev_class
= p
->sched_class
;
5231 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
5234 p
->sched_class
->set_curr_task(rq
);
5236 activate_task(rq
, p
, 0);
5238 check_class_changed(rq
, p
, prev_class
, oldprio
);
5239 task_rq_unlock(rq
, p
, &flags
);
5241 rt_mutex_adjust_pi(p
);
5247 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
5248 * @p: the task in question.
5249 * @policy: new policy.
5250 * @param: structure containing the new RT priority.
5252 * NOTE that the task may be already dead.
5254 int sched_setscheduler(struct task_struct
*p
, int policy
,
5255 const struct sched_param
*param
)
5257 return __sched_setscheduler(p
, policy
, param
, true);
5259 EXPORT_SYMBOL_GPL(sched_setscheduler
);
5262 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
5263 * @p: the task in question.
5264 * @policy: new policy.
5265 * @param: structure containing the new RT priority.
5267 * Just like sched_setscheduler, only don't bother checking if the
5268 * current context has permission. For example, this is needed in
5269 * stop_machine(): we create temporary high priority worker threads,
5270 * but our caller might not have that capability.
5272 int sched_setscheduler_nocheck(struct task_struct
*p
, int policy
,
5273 const struct sched_param
*param
)
5275 return __sched_setscheduler(p
, policy
, param
, false);
5279 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
5281 struct sched_param lparam
;
5282 struct task_struct
*p
;
5285 if (!param
|| pid
< 0)
5287 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
5292 p
= find_process_by_pid(pid
);
5294 retval
= sched_setscheduler(p
, policy
, &lparam
);
5301 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
5302 * @pid: the pid in question.
5303 * @policy: new policy.
5304 * @param: structure containing the new RT priority.
5306 SYSCALL_DEFINE3(sched_setscheduler
, pid_t
, pid
, int, policy
,
5307 struct sched_param __user
*, param
)
5309 /* negative values for policy are not valid */
5313 return do_sched_setscheduler(pid
, policy
, param
);
5317 * sys_sched_setparam - set/change the RT priority of a thread
5318 * @pid: the pid in question.
5319 * @param: structure containing the new RT priority.
5321 SYSCALL_DEFINE2(sched_setparam
, pid_t
, pid
, struct sched_param __user
*, param
)
5323 return do_sched_setscheduler(pid
, -1, param
);
5327 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
5328 * @pid: the pid in question.
5330 SYSCALL_DEFINE1(sched_getscheduler
, pid_t
, pid
)
5332 struct task_struct
*p
;
5340 p
= find_process_by_pid(pid
);
5342 retval
= security_task_getscheduler(p
);
5345 | (p
->sched_reset_on_fork
? SCHED_RESET_ON_FORK
: 0);
5352 * sys_sched_getparam - get the RT priority of a thread
5353 * @pid: the pid in question.
5354 * @param: structure containing the RT priority.
5356 SYSCALL_DEFINE2(sched_getparam
, pid_t
, pid
, struct sched_param __user
*, param
)
5358 struct sched_param lp
;
5359 struct task_struct
*p
;
5362 if (!param
|| pid
< 0)
5366 p
= find_process_by_pid(pid
);
5371 retval
= security_task_getscheduler(p
);
5375 lp
.sched_priority
= p
->rt_priority
;
5379 * This one might sleep, we cannot do it with a spinlock held ...
5381 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
5390 long sched_setaffinity(pid_t pid
, const struct cpumask
*in_mask
)
5392 cpumask_var_t cpus_allowed
, new_mask
;
5393 struct task_struct
*p
;
5399 p
= find_process_by_pid(pid
);
5406 /* Prevent p going away */
5410 if (!alloc_cpumask_var(&cpus_allowed
, GFP_KERNEL
)) {
5414 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
)) {
5416 goto out_free_cpus_allowed
;
5419 if (!check_same_owner(p
) && !task_ns_capable(p
, CAP_SYS_NICE
))
5422 retval
= security_task_setscheduler(p
);
5426 cpuset_cpus_allowed(p
, cpus_allowed
);
5427 cpumask_and(new_mask
, in_mask
, cpus_allowed
);
5429 retval
= set_cpus_allowed_ptr(p
, new_mask
);
5432 cpuset_cpus_allowed(p
, cpus_allowed
);
5433 if (!cpumask_subset(new_mask
, cpus_allowed
)) {
5435 * We must have raced with a concurrent cpuset
5436 * update. Just reset the cpus_allowed to the
5437 * cpuset's cpus_allowed
5439 cpumask_copy(new_mask
, cpus_allowed
);
5444 free_cpumask_var(new_mask
);
5445 out_free_cpus_allowed
:
5446 free_cpumask_var(cpus_allowed
);
5453 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
5454 struct cpumask
*new_mask
)
5456 if (len
< cpumask_size())
5457 cpumask_clear(new_mask
);
5458 else if (len
> cpumask_size())
5459 len
= cpumask_size();
5461 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
5465 * sys_sched_setaffinity - set the cpu affinity of a process
5466 * @pid: pid of the process
5467 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
5468 * @user_mask_ptr: user-space pointer to the new cpu mask
5470 SYSCALL_DEFINE3(sched_setaffinity
, pid_t
, pid
, unsigned int, len
,
5471 unsigned long __user
*, user_mask_ptr
)
5473 cpumask_var_t new_mask
;
5476 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
))
5479 retval
= get_user_cpu_mask(user_mask_ptr
, len
, new_mask
);
5481 retval
= sched_setaffinity(pid
, new_mask
);
5482 free_cpumask_var(new_mask
);
5486 long sched_getaffinity(pid_t pid
, struct cpumask
*mask
)
5488 struct task_struct
*p
;
5489 unsigned long flags
;
5496 p
= find_process_by_pid(pid
);
5500 retval
= security_task_getscheduler(p
);
5504 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
5505 cpumask_and(mask
, &p
->cpus_allowed
, cpu_online_mask
);
5506 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
5516 * sys_sched_getaffinity - get the cpu affinity of a process
5517 * @pid: pid of the process
5518 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
5519 * @user_mask_ptr: user-space pointer to hold the current cpu mask
5521 SYSCALL_DEFINE3(sched_getaffinity
, pid_t
, pid
, unsigned int, len
,
5522 unsigned long __user
*, user_mask_ptr
)
5527 if ((len
* BITS_PER_BYTE
) < nr_cpu_ids
)
5529 if (len
& (sizeof(unsigned long)-1))
5532 if (!alloc_cpumask_var(&mask
, GFP_KERNEL
))
5535 ret
= sched_getaffinity(pid
, mask
);
5537 size_t retlen
= min_t(size_t, len
, cpumask_size());
5539 if (copy_to_user(user_mask_ptr
, mask
, retlen
))
5544 free_cpumask_var(mask
);
5550 * sys_sched_yield - yield the current processor to other threads.
5552 * This function yields the current CPU to other tasks. If there are no
5553 * other threads running on this CPU then this function will return.
5555 SYSCALL_DEFINE0(sched_yield
)
5557 struct rq
*rq
= this_rq_lock();
5559 schedstat_inc(rq
, yld_count
);
5560 current
->sched_class
->yield_task(rq
);
5563 * Since we are going to call schedule() anyway, there's
5564 * no need to preempt or enable interrupts:
5566 __release(rq
->lock
);
5567 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
5568 do_raw_spin_unlock(&rq
->lock
);
5569 preempt_enable_no_resched();
5576 static inline int should_resched(void)
5578 return need_resched() && !(preempt_count() & PREEMPT_ACTIVE
);
5581 static void __cond_resched(void)
5583 add_preempt_count(PREEMPT_ACTIVE
);
5585 sub_preempt_count(PREEMPT_ACTIVE
);
5588 int __sched
_cond_resched(void)
5590 if (should_resched()) {
5596 EXPORT_SYMBOL(_cond_resched
);
5599 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
5600 * call schedule, and on return reacquire the lock.
5602 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
5603 * operations here to prevent schedule() from being called twice (once via
5604 * spin_unlock(), once by hand).
5606 int __cond_resched_lock(spinlock_t
*lock
)
5608 int resched
= should_resched();
5611 lockdep_assert_held(lock
);
5613 if (spin_needbreak(lock
) || resched
) {
5624 EXPORT_SYMBOL(__cond_resched_lock
);
5626 int __sched
__cond_resched_softirq(void)
5628 BUG_ON(!in_softirq());
5630 if (should_resched()) {
5638 EXPORT_SYMBOL(__cond_resched_softirq
);
5641 * yield - yield the current processor to other threads.
5643 * This is a shortcut for kernel-space yielding - it marks the
5644 * thread runnable and calls sys_sched_yield().
5646 void __sched
yield(void)
5648 set_current_state(TASK_RUNNING
);
5651 EXPORT_SYMBOL(yield
);
5654 * yield_to - yield the current processor to another thread in
5655 * your thread group, or accelerate that thread toward the
5656 * processor it's on.
5658 * @preempt: whether task preemption is allowed or not
5660 * It's the caller's job to ensure that the target task struct
5661 * can't go away on us before we can do any checks.
5663 * Returns true if we indeed boosted the target task.
5665 bool __sched
yield_to(struct task_struct
*p
, bool preempt
)
5667 struct task_struct
*curr
= current
;
5668 struct rq
*rq
, *p_rq
;
5669 unsigned long flags
;
5672 local_irq_save(flags
);
5677 double_rq_lock(rq
, p_rq
);
5678 while (task_rq(p
) != p_rq
) {
5679 double_rq_unlock(rq
, p_rq
);
5683 if (!curr
->sched_class
->yield_to_task
)
5686 if (curr
->sched_class
!= p
->sched_class
)
5689 if (task_running(p_rq
, p
) || p
->state
)
5692 yielded
= curr
->sched_class
->yield_to_task(rq
, p
, preempt
);
5694 schedstat_inc(rq
, yld_count
);
5696 * Make p's CPU reschedule; pick_next_entity takes care of
5699 if (preempt
&& rq
!= p_rq
)
5700 resched_task(p_rq
->curr
);
5704 double_rq_unlock(rq
, p_rq
);
5705 local_irq_restore(flags
);
5712 EXPORT_SYMBOL_GPL(yield_to
);
5715 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
5716 * that process accounting knows that this is a task in IO wait state.
5718 void __sched
io_schedule(void)
5720 struct rq
*rq
= raw_rq();
5722 delayacct_blkio_start();
5723 atomic_inc(&rq
->nr_iowait
);
5724 blk_flush_plug(current
);
5725 current
->in_iowait
= 1;
5727 current
->in_iowait
= 0;
5728 atomic_dec(&rq
->nr_iowait
);
5729 delayacct_blkio_end();
5731 EXPORT_SYMBOL(io_schedule
);
5733 long __sched
io_schedule_timeout(long timeout
)
5735 struct rq
*rq
= raw_rq();
5738 delayacct_blkio_start();
5739 atomic_inc(&rq
->nr_iowait
);
5740 blk_flush_plug(current
);
5741 current
->in_iowait
= 1;
5742 ret
= schedule_timeout(timeout
);
5743 current
->in_iowait
= 0;
5744 atomic_dec(&rq
->nr_iowait
);
5745 delayacct_blkio_end();
5750 * sys_sched_get_priority_max - return maximum RT priority.
5751 * @policy: scheduling class.
5753 * this syscall returns the maximum rt_priority that can be used
5754 * by a given scheduling class.
5756 SYSCALL_DEFINE1(sched_get_priority_max
, int, policy
)
5763 ret
= MAX_USER_RT_PRIO
-1;
5775 * sys_sched_get_priority_min - return minimum RT priority.
5776 * @policy: scheduling class.
5778 * this syscall returns the minimum rt_priority that can be used
5779 * by a given scheduling class.
5781 SYSCALL_DEFINE1(sched_get_priority_min
, int, policy
)
5799 * sys_sched_rr_get_interval - return the default timeslice of a process.
5800 * @pid: pid of the process.
5801 * @interval: userspace pointer to the timeslice value.
5803 * this syscall writes the default timeslice value of a given process
5804 * into the user-space timespec buffer. A value of '0' means infinity.
5806 SYSCALL_DEFINE2(sched_rr_get_interval
, pid_t
, pid
,
5807 struct timespec __user
*, interval
)
5809 struct task_struct
*p
;
5810 unsigned int time_slice
;
5811 unsigned long flags
;
5821 p
= find_process_by_pid(pid
);
5825 retval
= security_task_getscheduler(p
);
5829 rq
= task_rq_lock(p
, &flags
);
5830 time_slice
= p
->sched_class
->get_rr_interval(rq
, p
);
5831 task_rq_unlock(rq
, p
, &flags
);
5834 jiffies_to_timespec(time_slice
, &t
);
5835 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
5843 static const char stat_nam
[] = TASK_STATE_TO_CHAR_STR
;
5845 void sched_show_task(struct task_struct
*p
)
5847 unsigned long free
= 0;
5850 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
5851 printk(KERN_INFO
"%-15.15s %c", p
->comm
,
5852 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
5853 #if BITS_PER_LONG == 32
5854 if (state
== TASK_RUNNING
)
5855 printk(KERN_CONT
" running ");
5857 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
5859 if (state
== TASK_RUNNING
)
5860 printk(KERN_CONT
" running task ");
5862 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
5864 #ifdef CONFIG_DEBUG_STACK_USAGE
5865 free
= stack_not_used(p
);
5867 printk(KERN_CONT
"%5lu %5d %6d 0x%08lx\n", free
,
5868 task_pid_nr(p
), task_pid_nr(p
->real_parent
),
5869 (unsigned long)task_thread_info(p
)->flags
);
5871 show_stack(p
, NULL
);
5874 void show_state_filter(unsigned long state_filter
)
5876 struct task_struct
*g
, *p
;
5878 #if BITS_PER_LONG == 32
5880 " task PC stack pid father\n");
5883 " task PC stack pid father\n");
5885 read_lock(&tasklist_lock
);
5886 do_each_thread(g
, p
) {
5888 * reset the NMI-timeout, listing all files on a slow
5889 * console might take a lot of time:
5891 touch_nmi_watchdog();
5892 if (!state_filter
|| (p
->state
& state_filter
))
5894 } while_each_thread(g
, p
);
5896 touch_all_softlockup_watchdogs();
5898 #ifdef CONFIG_SCHED_DEBUG
5899 sysrq_sched_debug_show();
5901 read_unlock(&tasklist_lock
);
5903 * Only show locks if all tasks are dumped:
5906 debug_show_all_locks();
5909 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
5911 idle
->sched_class
= &idle_sched_class
;
5915 * init_idle - set up an idle thread for a given CPU
5916 * @idle: task in question
5917 * @cpu: cpu the idle task belongs to
5919 * NOTE: this function does not set the idle thread's NEED_RESCHED
5920 * flag, to make booting more robust.
5922 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
5924 struct rq
*rq
= cpu_rq(cpu
);
5925 unsigned long flags
;
5927 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5930 idle
->state
= TASK_RUNNING
;
5931 idle
->se
.exec_start
= sched_clock();
5933 do_set_cpus_allowed(idle
, cpumask_of(cpu
));
5935 * We're having a chicken and egg problem, even though we are
5936 * holding rq->lock, the cpu isn't yet set to this cpu so the
5937 * lockdep check in task_group() will fail.
5939 * Similar case to sched_fork(). / Alternatively we could
5940 * use task_rq_lock() here and obtain the other rq->lock.
5945 __set_task_cpu(idle
, cpu
);
5948 rq
->curr
= rq
->idle
= idle
;
5949 #if defined(CONFIG_SMP)
5952 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5954 /* Set the preempt count _outside_ the spinlocks! */
5955 task_thread_info(idle
)->preempt_count
= 0;
5958 * The idle tasks have their own, simple scheduling class:
5960 idle
->sched_class
= &idle_sched_class
;
5961 ftrace_graph_init_idle_task(idle
, cpu
);
5965 * In a system that switches off the HZ timer nohz_cpu_mask
5966 * indicates which cpus entered this state. This is used
5967 * in the rcu update to wait only for active cpus. For system
5968 * which do not switch off the HZ timer nohz_cpu_mask should
5969 * always be CPU_BITS_NONE.
5971 cpumask_var_t nohz_cpu_mask
;
5974 * Increase the granularity value when there are more CPUs,
5975 * because with more CPUs the 'effective latency' as visible
5976 * to users decreases. But the relationship is not linear,
5977 * so pick a second-best guess by going with the log2 of the
5980 * This idea comes from the SD scheduler of Con Kolivas:
5982 static int get_update_sysctl_factor(void)
5984 unsigned int cpus
= min_t(int, num_online_cpus(), 8);
5985 unsigned int factor
;
5987 switch (sysctl_sched_tunable_scaling
) {
5988 case SCHED_TUNABLESCALING_NONE
:
5991 case SCHED_TUNABLESCALING_LINEAR
:
5994 case SCHED_TUNABLESCALING_LOG
:
5996 factor
= 1 + ilog2(cpus
);
6003 static void update_sysctl(void)
6005 unsigned int factor
= get_update_sysctl_factor();
6007 #define SET_SYSCTL(name) \
6008 (sysctl_##name = (factor) * normalized_sysctl_##name)
6009 SET_SYSCTL(sched_min_granularity
);
6010 SET_SYSCTL(sched_latency
);
6011 SET_SYSCTL(sched_wakeup_granularity
);
6015 static inline void sched_init_granularity(void)
6021 void do_set_cpus_allowed(struct task_struct
*p
, const struct cpumask
*new_mask
)
6023 if (p
->sched_class
&& p
->sched_class
->set_cpus_allowed
)
6024 p
->sched_class
->set_cpus_allowed(p
, new_mask
);
6026 cpumask_copy(&p
->cpus_allowed
, new_mask
);
6027 p
->rt
.nr_cpus_allowed
= cpumask_weight(new_mask
);
6032 * This is how migration works:
6034 * 1) we invoke migration_cpu_stop() on the target CPU using
6036 * 2) stopper starts to run (implicitly forcing the migrated thread
6038 * 3) it checks whether the migrated task is still in the wrong runqueue.
6039 * 4) if it's in the wrong runqueue then the migration thread removes
6040 * it and puts it into the right queue.
6041 * 5) stopper completes and stop_one_cpu() returns and the migration
6046 * Change a given task's CPU affinity. Migrate the thread to a
6047 * proper CPU and schedule it away if the CPU it's executing on
6048 * is removed from the allowed bitmask.
6050 * NOTE: the caller must have a valid reference to the task, the
6051 * task must not exit() & deallocate itself prematurely. The
6052 * call is not atomic; no spinlocks may be held.
6054 int set_cpus_allowed_ptr(struct task_struct
*p
, const struct cpumask
*new_mask
)
6056 unsigned long flags
;
6058 unsigned int dest_cpu
;
6061 rq
= task_rq_lock(p
, &flags
);
6063 if (cpumask_equal(&p
->cpus_allowed
, new_mask
))
6066 if (!cpumask_intersects(new_mask
, cpu_active_mask
)) {
6071 if (unlikely((p
->flags
& PF_THREAD_BOUND
) && p
!= current
)) {
6076 do_set_cpus_allowed(p
, new_mask
);
6078 /* Can the task run on the task's current CPU? If so, we're done */
6079 if (cpumask_test_cpu(task_cpu(p
), new_mask
))
6082 dest_cpu
= cpumask_any_and(cpu_active_mask
, new_mask
);
6084 struct migration_arg arg
= { p
, dest_cpu
};
6085 /* Need help from migration thread: drop lock and wait. */
6086 task_rq_unlock(rq
, p
, &flags
);
6087 stop_one_cpu(cpu_of(rq
), migration_cpu_stop
, &arg
);
6088 tlb_migrate_finish(p
->mm
);
6092 task_rq_unlock(rq
, p
, &flags
);
6096 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr
);
6099 * Move (not current) task off this cpu, onto dest cpu. We're doing
6100 * this because either it can't run here any more (set_cpus_allowed()
6101 * away from this CPU, or CPU going down), or because we're
6102 * attempting to rebalance this task on exec (sched_exec).
6104 * So we race with normal scheduler movements, but that's OK, as long
6105 * as the task is no longer on this CPU.
6107 * Returns non-zero if task was successfully migrated.
6109 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
6111 struct rq
*rq_dest
, *rq_src
;
6114 if (unlikely(!cpu_active(dest_cpu
)))
6117 rq_src
= cpu_rq(src_cpu
);
6118 rq_dest
= cpu_rq(dest_cpu
);
6120 raw_spin_lock(&p
->pi_lock
);
6121 double_rq_lock(rq_src
, rq_dest
);
6122 /* Already moved. */
6123 if (task_cpu(p
) != src_cpu
)
6125 /* Affinity changed (again). */
6126 if (!cpumask_test_cpu(dest_cpu
, &p
->cpus_allowed
))
6130 * If we're not on a rq, the next wake-up will ensure we're
6134 deactivate_task(rq_src
, p
, 0);
6135 set_task_cpu(p
, dest_cpu
);
6136 activate_task(rq_dest
, p
, 0);
6137 check_preempt_curr(rq_dest
, p
, 0);
6142 double_rq_unlock(rq_src
, rq_dest
);
6143 raw_spin_unlock(&p
->pi_lock
);
6148 * migration_cpu_stop - this will be executed by a highprio stopper thread
6149 * and performs thread migration by bumping thread off CPU then
6150 * 'pushing' onto another runqueue.
6152 static int migration_cpu_stop(void *data
)
6154 struct migration_arg
*arg
= data
;
6157 * The original target cpu might have gone down and we might
6158 * be on another cpu but it doesn't matter.
6160 local_irq_disable();
6161 __migrate_task(arg
->task
, raw_smp_processor_id(), arg
->dest_cpu
);
6166 #ifdef CONFIG_HOTPLUG_CPU
6169 * Ensures that the idle task is using init_mm right before its cpu goes
6172 void idle_task_exit(void)
6174 struct mm_struct
*mm
= current
->active_mm
;
6176 BUG_ON(cpu_online(smp_processor_id()));
6179 switch_mm(mm
, &init_mm
, current
);
6184 * While a dead CPU has no uninterruptible tasks queued at this point,
6185 * it might still have a nonzero ->nr_uninterruptible counter, because
6186 * for performance reasons the counter is not stricly tracking tasks to
6187 * their home CPUs. So we just add the counter to another CPU's counter,
6188 * to keep the global sum constant after CPU-down:
6190 static void migrate_nr_uninterruptible(struct rq
*rq_src
)
6192 struct rq
*rq_dest
= cpu_rq(cpumask_any(cpu_active_mask
));
6194 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
6195 rq_src
->nr_uninterruptible
= 0;
6199 * remove the tasks which were accounted by rq from calc_load_tasks.
6201 static void calc_global_load_remove(struct rq
*rq
)
6203 atomic_long_sub(rq
->calc_load_active
, &calc_load_tasks
);
6204 rq
->calc_load_active
= 0;
6208 * Migrate all tasks from the rq, sleeping tasks will be migrated by
6209 * try_to_wake_up()->select_task_rq().
6211 * Called with rq->lock held even though we'er in stop_machine() and
6212 * there's no concurrency possible, we hold the required locks anyway
6213 * because of lock validation efforts.
6215 static void migrate_tasks(unsigned int dead_cpu
)
6217 struct rq
*rq
= cpu_rq(dead_cpu
);
6218 struct task_struct
*next
, *stop
= rq
->stop
;
6222 * Fudge the rq selection such that the below task selection loop
6223 * doesn't get stuck on the currently eligible stop task.
6225 * We're currently inside stop_machine() and the rq is either stuck
6226 * in the stop_machine_cpu_stop() loop, or we're executing this code,
6227 * either way we should never end up calling schedule() until we're
6234 * There's this thread running, bail when that's the only
6237 if (rq
->nr_running
== 1)
6240 next
= pick_next_task(rq
);
6242 next
->sched_class
->put_prev_task(rq
, next
);
6244 /* Find suitable destination for @next, with force if needed. */
6245 dest_cpu
= select_fallback_rq(dead_cpu
, next
);
6246 raw_spin_unlock(&rq
->lock
);
6248 __migrate_task(next
, dead_cpu
, dest_cpu
);
6250 raw_spin_lock(&rq
->lock
);
6256 #endif /* CONFIG_HOTPLUG_CPU */
6258 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
6260 static struct ctl_table sd_ctl_dir
[] = {
6262 .procname
= "sched_domain",
6268 static struct ctl_table sd_ctl_root
[] = {
6270 .procname
= "kernel",
6272 .child
= sd_ctl_dir
,
6277 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
6279 struct ctl_table
*entry
=
6280 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
6285 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
6287 struct ctl_table
*entry
;
6290 * In the intermediate directories, both the child directory and
6291 * procname are dynamically allocated and could fail but the mode
6292 * will always be set. In the lowest directory the names are
6293 * static strings and all have proc handlers.
6295 for (entry
= *tablep
; entry
->mode
; entry
++) {
6297 sd_free_ctl_entry(&entry
->child
);
6298 if (entry
->proc_handler
== NULL
)
6299 kfree(entry
->procname
);
6307 set_table_entry(struct ctl_table
*entry
,
6308 const char *procname
, void *data
, int maxlen
,
6309 mode_t mode
, proc_handler
*proc_handler
)
6311 entry
->procname
= procname
;
6313 entry
->maxlen
= maxlen
;
6315 entry
->proc_handler
= proc_handler
;
6318 static struct ctl_table
*
6319 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
6321 struct ctl_table
*table
= sd_alloc_ctl_entry(13);
6326 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
6327 sizeof(long), 0644, proc_doulongvec_minmax
);
6328 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
6329 sizeof(long), 0644, proc_doulongvec_minmax
);
6330 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
6331 sizeof(int), 0644, proc_dointvec_minmax
);
6332 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
6333 sizeof(int), 0644, proc_dointvec_minmax
);
6334 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
6335 sizeof(int), 0644, proc_dointvec_minmax
);
6336 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
6337 sizeof(int), 0644, proc_dointvec_minmax
);
6338 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
6339 sizeof(int), 0644, proc_dointvec_minmax
);
6340 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
6341 sizeof(int), 0644, proc_dointvec_minmax
);
6342 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
6343 sizeof(int), 0644, proc_dointvec_minmax
);
6344 set_table_entry(&table
[9], "cache_nice_tries",
6345 &sd
->cache_nice_tries
,
6346 sizeof(int), 0644, proc_dointvec_minmax
);
6347 set_table_entry(&table
[10], "flags", &sd
->flags
,
6348 sizeof(int), 0644, proc_dointvec_minmax
);
6349 set_table_entry(&table
[11], "name", sd
->name
,
6350 CORENAME_MAX_SIZE
, 0444, proc_dostring
);
6351 /* &table[12] is terminator */
6356 static ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
6358 struct ctl_table
*entry
, *table
;
6359 struct sched_domain
*sd
;
6360 int domain_num
= 0, i
;
6363 for_each_domain(cpu
, sd
)
6365 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
6370 for_each_domain(cpu
, sd
) {
6371 snprintf(buf
, 32, "domain%d", i
);
6372 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
6374 entry
->child
= sd_alloc_ctl_domain_table(sd
);
6381 static struct ctl_table_header
*sd_sysctl_header
;
6382 static void register_sched_domain_sysctl(void)
6384 int i
, cpu_num
= num_possible_cpus();
6385 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
6388 WARN_ON(sd_ctl_dir
[0].child
);
6389 sd_ctl_dir
[0].child
= entry
;
6394 for_each_possible_cpu(i
) {
6395 snprintf(buf
, 32, "cpu%d", i
);
6396 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
6398 entry
->child
= sd_alloc_ctl_cpu_table(i
);
6402 WARN_ON(sd_sysctl_header
);
6403 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
6406 /* may be called multiple times per register */
6407 static void unregister_sched_domain_sysctl(void)
6409 if (sd_sysctl_header
)
6410 unregister_sysctl_table(sd_sysctl_header
);
6411 sd_sysctl_header
= NULL
;
6412 if (sd_ctl_dir
[0].child
)
6413 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
6416 static void register_sched_domain_sysctl(void)
6419 static void unregister_sched_domain_sysctl(void)
6424 static void set_rq_online(struct rq
*rq
)
6427 const struct sched_class
*class;
6429 cpumask_set_cpu(rq
->cpu
, rq
->rd
->online
);
6432 for_each_class(class) {
6433 if (class->rq_online
)
6434 class->rq_online(rq
);
6439 static void set_rq_offline(struct rq
*rq
)
6442 const struct sched_class
*class;
6444 for_each_class(class) {
6445 if (class->rq_offline
)
6446 class->rq_offline(rq
);
6449 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->online
);
6455 * migration_call - callback that gets triggered when a CPU is added.
6456 * Here we can start up the necessary migration thread for the new CPU.
6458 static int __cpuinit
6459 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
6461 int cpu
= (long)hcpu
;
6462 unsigned long flags
;
6463 struct rq
*rq
= cpu_rq(cpu
);
6465 switch (action
& ~CPU_TASKS_FROZEN
) {
6467 case CPU_UP_PREPARE
:
6468 rq
->calc_load_update
= calc_load_update
;
6472 /* Update our root-domain */
6473 raw_spin_lock_irqsave(&rq
->lock
, flags
);
6475 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
6479 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
6482 #ifdef CONFIG_HOTPLUG_CPU
6484 sched_ttwu_pending();
6485 /* Update our root-domain */
6486 raw_spin_lock_irqsave(&rq
->lock
, flags
);
6488 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
6492 BUG_ON(rq
->nr_running
!= 1); /* the migration thread */
6493 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
6495 migrate_nr_uninterruptible(rq
);
6496 calc_global_load_remove(rq
);
6501 update_max_interval();
6507 * Register at high priority so that task migration (migrate_all_tasks)
6508 * happens before everything else. This has to be lower priority than
6509 * the notifier in the perf_event subsystem, though.
6511 static struct notifier_block __cpuinitdata migration_notifier
= {
6512 .notifier_call
= migration_call
,
6513 .priority
= CPU_PRI_MIGRATION
,
6516 static int __cpuinit
sched_cpu_active(struct notifier_block
*nfb
,
6517 unsigned long action
, void *hcpu
)
6519 switch (action
& ~CPU_TASKS_FROZEN
) {
6521 case CPU_DOWN_FAILED
:
6522 set_cpu_active((long)hcpu
, true);
6529 static int __cpuinit
sched_cpu_inactive(struct notifier_block
*nfb
,
6530 unsigned long action
, void *hcpu
)
6532 switch (action
& ~CPU_TASKS_FROZEN
) {
6533 case CPU_DOWN_PREPARE
:
6534 set_cpu_active((long)hcpu
, false);
6541 static int __init
migration_init(void)
6543 void *cpu
= (void *)(long)smp_processor_id();
6546 /* Initialize migration for the boot CPU */
6547 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
6548 BUG_ON(err
== NOTIFY_BAD
);
6549 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
6550 register_cpu_notifier(&migration_notifier
);
6552 /* Register cpu active notifiers */
6553 cpu_notifier(sched_cpu_active
, CPU_PRI_SCHED_ACTIVE
);
6554 cpu_notifier(sched_cpu_inactive
, CPU_PRI_SCHED_INACTIVE
);
6558 early_initcall(migration_init
);
6563 static cpumask_var_t sched_domains_tmpmask
; /* sched_domains_mutex */
6565 #ifdef CONFIG_SCHED_DEBUG
6567 static __read_mostly
int sched_domain_debug_enabled
;
6569 static int __init
sched_domain_debug_setup(char *str
)
6571 sched_domain_debug_enabled
= 1;
6575 early_param("sched_debug", sched_domain_debug_setup
);
6577 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
,
6578 struct cpumask
*groupmask
)
6580 struct sched_group
*group
= sd
->groups
;
6583 cpulist_scnprintf(str
, sizeof(str
), sched_domain_span(sd
));
6584 cpumask_clear(groupmask
);
6586 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
6588 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
6589 printk("does not load-balance\n");
6591 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
6596 printk(KERN_CONT
"span %s level %s\n", str
, sd
->name
);
6598 if (!cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
6599 printk(KERN_ERR
"ERROR: domain->span does not contain "
6602 if (!cpumask_test_cpu(cpu
, sched_group_cpus(group
))) {
6603 printk(KERN_ERR
"ERROR: domain->groups does not contain"
6607 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
6611 printk(KERN_ERR
"ERROR: group is NULL\n");
6615 if (!group
->sgp
->power
) {
6616 printk(KERN_CONT
"\n");
6617 printk(KERN_ERR
"ERROR: domain->cpu_power not "
6622 if (!cpumask_weight(sched_group_cpus(group
))) {
6623 printk(KERN_CONT
"\n");
6624 printk(KERN_ERR
"ERROR: empty group\n");
6628 if (cpumask_intersects(groupmask
, sched_group_cpus(group
))) {
6629 printk(KERN_CONT
"\n");
6630 printk(KERN_ERR
"ERROR: repeated CPUs\n");
6634 cpumask_or(groupmask
, groupmask
, sched_group_cpus(group
));
6636 cpulist_scnprintf(str
, sizeof(str
), sched_group_cpus(group
));
6638 printk(KERN_CONT
" %s", str
);
6639 if (group
->sgp
->power
!= SCHED_POWER_SCALE
) {
6640 printk(KERN_CONT
" (cpu_power = %d)",
6644 group
= group
->next
;
6645 } while (group
!= sd
->groups
);
6646 printk(KERN_CONT
"\n");
6648 if (!cpumask_equal(sched_domain_span(sd
), groupmask
))
6649 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
6652 !cpumask_subset(groupmask
, sched_domain_span(sd
->parent
)))
6653 printk(KERN_ERR
"ERROR: parent span is not a superset "
6654 "of domain->span\n");
6658 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
6662 if (!sched_domain_debug_enabled
)
6666 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
6670 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
6673 if (sched_domain_debug_one(sd
, cpu
, level
, sched_domains_tmpmask
))
6681 #else /* !CONFIG_SCHED_DEBUG */
6682 # define sched_domain_debug(sd, cpu) do { } while (0)
6683 #endif /* CONFIG_SCHED_DEBUG */
6685 static int sd_degenerate(struct sched_domain
*sd
)
6687 if (cpumask_weight(sched_domain_span(sd
)) == 1)
6690 /* Following flags need at least 2 groups */
6691 if (sd
->flags
& (SD_LOAD_BALANCE
|
6692 SD_BALANCE_NEWIDLE
|
6696 SD_SHARE_PKG_RESOURCES
)) {
6697 if (sd
->groups
!= sd
->groups
->next
)
6701 /* Following flags don't use groups */
6702 if (sd
->flags
& (SD_WAKE_AFFINE
))
6709 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
6711 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
6713 if (sd_degenerate(parent
))
6716 if (!cpumask_equal(sched_domain_span(sd
), sched_domain_span(parent
)))
6719 /* Flags needing groups don't count if only 1 group in parent */
6720 if (parent
->groups
== parent
->groups
->next
) {
6721 pflags
&= ~(SD_LOAD_BALANCE
|
6722 SD_BALANCE_NEWIDLE
|
6726 SD_SHARE_PKG_RESOURCES
);
6727 if (nr_node_ids
== 1)
6728 pflags
&= ~SD_SERIALIZE
;
6730 if (~cflags
& pflags
)
6736 static void free_rootdomain(struct rcu_head
*rcu
)
6738 struct root_domain
*rd
= container_of(rcu
, struct root_domain
, rcu
);
6740 cpupri_cleanup(&rd
->cpupri
);
6741 free_cpumask_var(rd
->rto_mask
);
6742 free_cpumask_var(rd
->online
);
6743 free_cpumask_var(rd
->span
);
6747 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
6749 struct root_domain
*old_rd
= NULL
;
6750 unsigned long flags
;
6752 raw_spin_lock_irqsave(&rq
->lock
, flags
);
6757 if (cpumask_test_cpu(rq
->cpu
, old_rd
->online
))
6760 cpumask_clear_cpu(rq
->cpu
, old_rd
->span
);
6763 * If we dont want to free the old_rt yet then
6764 * set old_rd to NULL to skip the freeing later
6767 if (!atomic_dec_and_test(&old_rd
->refcount
))
6771 atomic_inc(&rd
->refcount
);
6774 cpumask_set_cpu(rq
->cpu
, rd
->span
);
6775 if (cpumask_test_cpu(rq
->cpu
, cpu_active_mask
))
6778 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
6781 call_rcu_sched(&old_rd
->rcu
, free_rootdomain
);
6784 static int init_rootdomain(struct root_domain
*rd
)
6786 memset(rd
, 0, sizeof(*rd
));
6788 if (!alloc_cpumask_var(&rd
->span
, GFP_KERNEL
))
6790 if (!alloc_cpumask_var(&rd
->online
, GFP_KERNEL
))
6792 if (!alloc_cpumask_var(&rd
->rto_mask
, GFP_KERNEL
))
6795 if (cpupri_init(&rd
->cpupri
) != 0)
6800 free_cpumask_var(rd
->rto_mask
);
6802 free_cpumask_var(rd
->online
);
6804 free_cpumask_var(rd
->span
);
6809 static void init_defrootdomain(void)
6811 init_rootdomain(&def_root_domain
);
6813 atomic_set(&def_root_domain
.refcount
, 1);
6816 static struct root_domain
*alloc_rootdomain(void)
6818 struct root_domain
*rd
;
6820 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
6824 if (init_rootdomain(rd
) != 0) {
6832 static void free_sched_groups(struct sched_group
*sg
, int free_sgp
)
6834 struct sched_group
*tmp
, *first
;
6843 if (free_sgp
&& atomic_dec_and_test(&sg
->sgp
->ref
))
6848 } while (sg
!= first
);
6851 static void free_sched_domain(struct rcu_head
*rcu
)
6853 struct sched_domain
*sd
= container_of(rcu
, struct sched_domain
, rcu
);
6856 * If its an overlapping domain it has private groups, iterate and
6859 if (sd
->flags
& SD_OVERLAP
) {
6860 free_sched_groups(sd
->groups
, 1);
6861 } else if (atomic_dec_and_test(&sd
->groups
->ref
)) {
6862 kfree(sd
->groups
->sgp
);
6868 static void destroy_sched_domain(struct sched_domain
*sd
, int cpu
)
6870 call_rcu(&sd
->rcu
, free_sched_domain
);
6873 static void destroy_sched_domains(struct sched_domain
*sd
, int cpu
)
6875 for (; sd
; sd
= sd
->parent
)
6876 destroy_sched_domain(sd
, cpu
);
6880 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
6881 * hold the hotplug lock.
6884 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
6886 struct rq
*rq
= cpu_rq(cpu
);
6887 struct sched_domain
*tmp
;
6889 /* Remove the sched domains which do not contribute to scheduling. */
6890 for (tmp
= sd
; tmp
; ) {
6891 struct sched_domain
*parent
= tmp
->parent
;
6895 if (sd_parent_degenerate(tmp
, parent
)) {
6896 tmp
->parent
= parent
->parent
;
6898 parent
->parent
->child
= tmp
;
6899 destroy_sched_domain(parent
, cpu
);
6904 if (sd
&& sd_degenerate(sd
)) {
6907 destroy_sched_domain(tmp
, cpu
);
6912 sched_domain_debug(sd
, cpu
);
6914 rq_attach_root(rq
, rd
);
6916 rcu_assign_pointer(rq
->sd
, sd
);
6917 destroy_sched_domains(tmp
, cpu
);
6920 /* cpus with isolated domains */
6921 static cpumask_var_t cpu_isolated_map
;
6923 /* Setup the mask of cpus configured for isolated domains */
6924 static int __init
isolated_cpu_setup(char *str
)
6926 alloc_bootmem_cpumask_var(&cpu_isolated_map
);
6927 cpulist_parse(str
, cpu_isolated_map
);
6931 __setup("isolcpus=", isolated_cpu_setup
);
6933 #define SD_NODES_PER_DOMAIN 16
6938 * find_next_best_node - find the next node to include in a sched_domain
6939 * @node: node whose sched_domain we're building
6940 * @used_nodes: nodes already in the sched_domain
6942 * Find the next node to include in a given scheduling domain. Simply
6943 * finds the closest node not already in the @used_nodes map.
6945 * Should use nodemask_t.
6947 static int find_next_best_node(int node
, nodemask_t
*used_nodes
)
6949 int i
, n
, val
, min_val
, best_node
= -1;
6953 for (i
= 0; i
< nr_node_ids
; i
++) {
6954 /* Start at @node */
6955 n
= (node
+ i
) % nr_node_ids
;
6957 if (!nr_cpus_node(n
))
6960 /* Skip already used nodes */
6961 if (node_isset(n
, *used_nodes
))
6964 /* Simple min distance search */
6965 val
= node_distance(node
, n
);
6967 if (val
< min_val
) {
6973 if (best_node
!= -1)
6974 node_set(best_node
, *used_nodes
);
6979 * sched_domain_node_span - get a cpumask for a node's sched_domain
6980 * @node: node whose cpumask we're constructing
6981 * @span: resulting cpumask
6983 * Given a node, construct a good cpumask for its sched_domain to span. It
6984 * should be one that prevents unnecessary balancing, but also spreads tasks
6987 static void sched_domain_node_span(int node
, struct cpumask
*span
)
6989 nodemask_t used_nodes
;
6992 cpumask_clear(span
);
6993 nodes_clear(used_nodes
);
6995 cpumask_or(span
, span
, cpumask_of_node(node
));
6996 node_set(node
, used_nodes
);
6998 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
6999 int next_node
= find_next_best_node(node
, &used_nodes
);
7002 cpumask_or(span
, span
, cpumask_of_node(next_node
));
7006 static const struct cpumask
*cpu_node_mask(int cpu
)
7008 lockdep_assert_held(&sched_domains_mutex
);
7010 sched_domain_node_span(cpu_to_node(cpu
), sched_domains_tmpmask
);
7012 return sched_domains_tmpmask
;
7015 static const struct cpumask
*cpu_allnodes_mask(int cpu
)
7017 return cpu_possible_mask
;
7019 #endif /* CONFIG_NUMA */
7021 static const struct cpumask
*cpu_cpu_mask(int cpu
)
7023 return cpumask_of_node(cpu_to_node(cpu
));
7026 int sched_smt_power_savings
= 0, sched_mc_power_savings
= 0;
7029 struct sched_domain
**__percpu sd
;
7030 struct sched_group
**__percpu sg
;
7031 struct sched_group_power
**__percpu sgp
;
7035 struct sched_domain
** __percpu sd
;
7036 struct root_domain
*rd
;
7046 struct sched_domain_topology_level
;
7048 typedef struct sched_domain
*(*sched_domain_init_f
)(struct sched_domain_topology_level
*tl
, int cpu
);
7049 typedef const struct cpumask
*(*sched_domain_mask_f
)(int cpu
);
7051 #define SDTL_OVERLAP 0x01
7053 struct sched_domain_topology_level
{
7054 sched_domain_init_f init
;
7055 sched_domain_mask_f mask
;
7057 struct sd_data data
;
7061 build_overlap_sched_groups(struct sched_domain
*sd
, int cpu
)
7063 struct sched_group
*first
= NULL
, *last
= NULL
, *groups
= NULL
, *sg
;
7064 const struct cpumask
*span
= sched_domain_span(sd
);
7065 struct cpumask
*covered
= sched_domains_tmpmask
;
7066 struct sd_data
*sdd
= sd
->private;
7067 struct sched_domain
*child
;
7070 cpumask_clear(covered
);
7072 for_each_cpu(i
, span
) {
7073 struct cpumask
*sg_span
;
7075 if (cpumask_test_cpu(i
, covered
))
7078 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
7079 GFP_KERNEL
, cpu_to_node(i
));
7084 sg_span
= sched_group_cpus(sg
);
7086 child
= *per_cpu_ptr(sdd
->sd
, i
);
7088 child
= child
->child
;
7089 cpumask_copy(sg_span
, sched_domain_span(child
));
7091 cpumask_set_cpu(i
, sg_span
);
7093 cpumask_or(covered
, covered
, sg_span
);
7095 sg
->sgp
= *per_cpu_ptr(sdd
->sgp
, cpumask_first(sg_span
));
7096 atomic_inc(&sg
->sgp
->ref
);
7098 if (cpumask_test_cpu(cpu
, sg_span
))
7108 sd
->groups
= groups
;
7113 free_sched_groups(first
, 0);
7118 static int get_group(int cpu
, struct sd_data
*sdd
, struct sched_group
**sg
)
7120 struct sched_domain
*sd
= *per_cpu_ptr(sdd
->sd
, cpu
);
7121 struct sched_domain
*child
= sd
->child
;
7124 cpu
= cpumask_first(sched_domain_span(child
));
7127 *sg
= *per_cpu_ptr(sdd
->sg
, cpu
);
7128 (*sg
)->sgp
= *per_cpu_ptr(sdd
->sgp
, cpu
);
7129 atomic_set(&(*sg
)->sgp
->ref
, 1); /* for claim_allocations */
7136 * build_sched_groups will build a circular linked list of the groups
7137 * covered by the given span, and will set each group's ->cpumask correctly,
7138 * and ->cpu_power to 0.
7140 * Assumes the sched_domain tree is fully constructed
7143 build_sched_groups(struct sched_domain
*sd
, int cpu
)
7145 struct sched_group
*first
= NULL
, *last
= NULL
;
7146 struct sd_data
*sdd
= sd
->private;
7147 const struct cpumask
*span
= sched_domain_span(sd
);
7148 struct cpumask
*covered
;
7151 get_group(cpu
, sdd
, &sd
->groups
);
7152 atomic_inc(&sd
->groups
->ref
);
7154 if (cpu
!= cpumask_first(sched_domain_span(sd
)))
7157 lockdep_assert_held(&sched_domains_mutex
);
7158 covered
= sched_domains_tmpmask
;
7160 cpumask_clear(covered
);
7162 for_each_cpu(i
, span
) {
7163 struct sched_group
*sg
;
7164 int group
= get_group(i
, sdd
, &sg
);
7167 if (cpumask_test_cpu(i
, covered
))
7170 cpumask_clear(sched_group_cpus(sg
));
7173 for_each_cpu(j
, span
) {
7174 if (get_group(j
, sdd
, NULL
) != group
)
7177 cpumask_set_cpu(j
, covered
);
7178 cpumask_set_cpu(j
, sched_group_cpus(sg
));
7193 * Initialize sched groups cpu_power.
7195 * cpu_power indicates the capacity of sched group, which is used while
7196 * distributing the load between different sched groups in a sched domain.
7197 * Typically cpu_power for all the groups in a sched domain will be same unless
7198 * there are asymmetries in the topology. If there are asymmetries, group
7199 * having more cpu_power will pickup more load compared to the group having
7202 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
7204 struct sched_group
*sg
= sd
->groups
;
7206 WARN_ON(!sd
|| !sg
);
7209 sg
->group_weight
= cpumask_weight(sched_group_cpus(sg
));
7211 } while (sg
!= sd
->groups
);
7213 if (cpu
!= group_first_cpu(sg
))
7216 update_group_power(sd
, cpu
);
7220 * Initializers for schedule domains
7221 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
7224 #ifdef CONFIG_SCHED_DEBUG
7225 # define SD_INIT_NAME(sd, type) sd->name = #type
7227 # define SD_INIT_NAME(sd, type) do { } while (0)
7230 #define SD_INIT_FUNC(type) \
7231 static noinline struct sched_domain * \
7232 sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \
7234 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \
7235 *sd = SD_##type##_INIT; \
7236 SD_INIT_NAME(sd, type); \
7237 sd->private = &tl->data; \
7243 SD_INIT_FUNC(ALLNODES
)
7246 #ifdef CONFIG_SCHED_SMT
7247 SD_INIT_FUNC(SIBLING
)
7249 #ifdef CONFIG_SCHED_MC
7252 #ifdef CONFIG_SCHED_BOOK
7256 static int default_relax_domain_level
= -1;
7257 int sched_domain_level_max
;
7259 static int __init
setup_relax_domain_level(char *str
)
7263 val
= simple_strtoul(str
, NULL
, 0);
7264 if (val
< sched_domain_level_max
)
7265 default_relax_domain_level
= val
;
7269 __setup("relax_domain_level=", setup_relax_domain_level
);
7271 static void set_domain_attribute(struct sched_domain
*sd
,
7272 struct sched_domain_attr
*attr
)
7276 if (!attr
|| attr
->relax_domain_level
< 0) {
7277 if (default_relax_domain_level
< 0)
7280 request
= default_relax_domain_level
;
7282 request
= attr
->relax_domain_level
;
7283 if (request
< sd
->level
) {
7284 /* turn off idle balance on this domain */
7285 sd
->flags
&= ~(SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
7287 /* turn on idle balance on this domain */
7288 sd
->flags
|= (SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
7292 static void __sdt_free(const struct cpumask
*cpu_map
);
7293 static int __sdt_alloc(const struct cpumask
*cpu_map
);
7295 static void __free_domain_allocs(struct s_data
*d
, enum s_alloc what
,
7296 const struct cpumask
*cpu_map
)
7300 if (!atomic_read(&d
->rd
->refcount
))
7301 free_rootdomain(&d
->rd
->rcu
); /* fall through */
7303 free_percpu(d
->sd
); /* fall through */
7305 __sdt_free(cpu_map
); /* fall through */
7311 static enum s_alloc
__visit_domain_allocation_hell(struct s_data
*d
,
7312 const struct cpumask
*cpu_map
)
7314 memset(d
, 0, sizeof(*d
));
7316 if (__sdt_alloc(cpu_map
))
7317 return sa_sd_storage
;
7318 d
->sd
= alloc_percpu(struct sched_domain
*);
7320 return sa_sd_storage
;
7321 d
->rd
= alloc_rootdomain();
7324 return sa_rootdomain
;
7328 * NULL the sd_data elements we've used to build the sched_domain and
7329 * sched_group structure so that the subsequent __free_domain_allocs()
7330 * will not free the data we're using.
7332 static void claim_allocations(int cpu
, struct sched_domain
*sd
)
7334 struct sd_data
*sdd
= sd
->private;
7336 WARN_ON_ONCE(*per_cpu_ptr(sdd
->sd
, cpu
) != sd
);
7337 *per_cpu_ptr(sdd
->sd
, cpu
) = NULL
;
7339 if (atomic_read(&(*per_cpu_ptr(sdd
->sg
, cpu
))->ref
))
7340 *per_cpu_ptr(sdd
->sg
, cpu
) = NULL
;
7342 if (atomic_read(&(*per_cpu_ptr(sdd
->sgp
, cpu
))->ref
))
7343 *per_cpu_ptr(sdd
->sgp
, cpu
) = NULL
;
7346 #ifdef CONFIG_SCHED_SMT
7347 static const struct cpumask
*cpu_smt_mask(int cpu
)
7349 return topology_thread_cpumask(cpu
);
7354 * Topology list, bottom-up.
7356 static struct sched_domain_topology_level default_topology
[] = {
7357 #ifdef CONFIG_SCHED_SMT
7358 { sd_init_SIBLING
, cpu_smt_mask
, },
7360 #ifdef CONFIG_SCHED_MC
7361 { sd_init_MC
, cpu_coregroup_mask
, },
7363 #ifdef CONFIG_SCHED_BOOK
7364 { sd_init_BOOK
, cpu_book_mask
, },
7366 { sd_init_CPU
, cpu_cpu_mask
, },
7368 { sd_init_NODE
, cpu_node_mask
, SDTL_OVERLAP
, },
7369 { sd_init_ALLNODES
, cpu_allnodes_mask
, },
7374 static struct sched_domain_topology_level
*sched_domain_topology
= default_topology
;
7376 static int __sdt_alloc(const struct cpumask
*cpu_map
)
7378 struct sched_domain_topology_level
*tl
;
7381 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
7382 struct sd_data
*sdd
= &tl
->data
;
7384 sdd
->sd
= alloc_percpu(struct sched_domain
*);
7388 sdd
->sg
= alloc_percpu(struct sched_group
*);
7392 sdd
->sgp
= alloc_percpu(struct sched_group_power
*);
7396 for_each_cpu(j
, cpu_map
) {
7397 struct sched_domain
*sd
;
7398 struct sched_group
*sg
;
7399 struct sched_group_power
*sgp
;
7401 sd
= kzalloc_node(sizeof(struct sched_domain
) + cpumask_size(),
7402 GFP_KERNEL
, cpu_to_node(j
));
7406 *per_cpu_ptr(sdd
->sd
, j
) = sd
;
7408 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
7409 GFP_KERNEL
, cpu_to_node(j
));
7413 *per_cpu_ptr(sdd
->sg
, j
) = sg
;
7415 sgp
= kzalloc_node(sizeof(struct sched_group_power
),
7416 GFP_KERNEL
, cpu_to_node(j
));
7420 *per_cpu_ptr(sdd
->sgp
, j
) = sgp
;
7427 static void __sdt_free(const struct cpumask
*cpu_map
)
7429 struct sched_domain_topology_level
*tl
;
7432 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
7433 struct sd_data
*sdd
= &tl
->data
;
7435 for_each_cpu(j
, cpu_map
) {
7436 struct sched_domain
*sd
= *per_cpu_ptr(sdd
->sd
, j
);
7437 if (sd
&& (sd
->flags
& SD_OVERLAP
))
7438 free_sched_groups(sd
->groups
, 0);
7439 kfree(*per_cpu_ptr(sdd
->sg
, j
));
7440 kfree(*per_cpu_ptr(sdd
->sgp
, j
));
7442 free_percpu(sdd
->sd
);
7443 free_percpu(sdd
->sg
);
7444 free_percpu(sdd
->sgp
);
7448 struct sched_domain
*build_sched_domain(struct sched_domain_topology_level
*tl
,
7449 struct s_data
*d
, const struct cpumask
*cpu_map
,
7450 struct sched_domain_attr
*attr
, struct sched_domain
*child
,
7453 struct sched_domain
*sd
= tl
->init(tl
, cpu
);
7457 set_domain_attribute(sd
, attr
);
7458 cpumask_and(sched_domain_span(sd
), cpu_map
, tl
->mask(cpu
));
7460 sd
->level
= child
->level
+ 1;
7461 sched_domain_level_max
= max(sched_domain_level_max
, sd
->level
);
7470 * Build sched domains for a given set of cpus and attach the sched domains
7471 * to the individual cpus
7473 static int build_sched_domains(const struct cpumask
*cpu_map
,
7474 struct sched_domain_attr
*attr
)
7476 enum s_alloc alloc_state
= sa_none
;
7477 struct sched_domain
*sd
;
7479 int i
, ret
= -ENOMEM
;
7481 alloc_state
= __visit_domain_allocation_hell(&d
, cpu_map
);
7482 if (alloc_state
!= sa_rootdomain
)
7485 /* Set up domains for cpus specified by the cpu_map. */
7486 for_each_cpu(i
, cpu_map
) {
7487 struct sched_domain_topology_level
*tl
;
7490 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
7491 sd
= build_sched_domain(tl
, &d
, cpu_map
, attr
, sd
, i
);
7492 if (tl
->flags
& SDTL_OVERLAP
|| sched_feat(FORCE_SD_OVERLAP
))
7493 sd
->flags
|= SD_OVERLAP
;
7494 if (cpumask_equal(cpu_map
, sched_domain_span(sd
)))
7501 *per_cpu_ptr(d
.sd
, i
) = sd
;
7504 /* Build the groups for the domains */
7505 for_each_cpu(i
, cpu_map
) {
7506 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
7507 sd
->span_weight
= cpumask_weight(sched_domain_span(sd
));
7508 if (sd
->flags
& SD_OVERLAP
) {
7509 if (build_overlap_sched_groups(sd
, i
))
7512 if (build_sched_groups(sd
, i
))
7518 /* Calculate CPU power for physical packages and nodes */
7519 for (i
= nr_cpumask_bits
-1; i
>= 0; i
--) {
7520 if (!cpumask_test_cpu(i
, cpu_map
))
7523 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
7524 claim_allocations(i
, sd
);
7525 init_sched_groups_power(i
, sd
);
7529 /* Attach the domains */
7531 for_each_cpu(i
, cpu_map
) {
7532 sd
= *per_cpu_ptr(d
.sd
, i
);
7533 cpu_attach_domain(sd
, d
.rd
, i
);
7539 __free_domain_allocs(&d
, alloc_state
, cpu_map
);
7543 static cpumask_var_t
*doms_cur
; /* current sched domains */
7544 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
7545 static struct sched_domain_attr
*dattr_cur
;
7546 /* attribues of custom domains in 'doms_cur' */
7549 * Special case: If a kmalloc of a doms_cur partition (array of
7550 * cpumask) fails, then fallback to a single sched domain,
7551 * as determined by the single cpumask fallback_doms.
7553 static cpumask_var_t fallback_doms
;
7556 * arch_update_cpu_topology lets virtualized architectures update the
7557 * cpu core maps. It is supposed to return 1 if the topology changed
7558 * or 0 if it stayed the same.
7560 int __attribute__((weak
)) arch_update_cpu_topology(void)
7565 cpumask_var_t
*alloc_sched_domains(unsigned int ndoms
)
7568 cpumask_var_t
*doms
;
7570 doms
= kmalloc(sizeof(*doms
) * ndoms
, GFP_KERNEL
);
7573 for (i
= 0; i
< ndoms
; i
++) {
7574 if (!alloc_cpumask_var(&doms
[i
], GFP_KERNEL
)) {
7575 free_sched_domains(doms
, i
);
7582 void free_sched_domains(cpumask_var_t doms
[], unsigned int ndoms
)
7585 for (i
= 0; i
< ndoms
; i
++)
7586 free_cpumask_var(doms
[i
]);
7591 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
7592 * For now this just excludes isolated cpus, but could be used to
7593 * exclude other special cases in the future.
7595 static int init_sched_domains(const struct cpumask
*cpu_map
)
7599 arch_update_cpu_topology();
7601 doms_cur
= alloc_sched_domains(ndoms_cur
);
7603 doms_cur
= &fallback_doms
;
7604 cpumask_andnot(doms_cur
[0], cpu_map
, cpu_isolated_map
);
7606 err
= build_sched_domains(doms_cur
[0], NULL
);
7607 register_sched_domain_sysctl();
7613 * Detach sched domains from a group of cpus specified in cpu_map
7614 * These cpus will now be attached to the NULL domain
7616 static void detach_destroy_domains(const struct cpumask
*cpu_map
)
7621 for_each_cpu(i
, cpu_map
)
7622 cpu_attach_domain(NULL
, &def_root_domain
, i
);
7626 /* handle null as "default" */
7627 static int dattrs_equal(struct sched_domain_attr
*cur
, int idx_cur
,
7628 struct sched_domain_attr
*new, int idx_new
)
7630 struct sched_domain_attr tmp
;
7637 return !memcmp(cur
? (cur
+ idx_cur
) : &tmp
,
7638 new ? (new + idx_new
) : &tmp
,
7639 sizeof(struct sched_domain_attr
));
7643 * Partition sched domains as specified by the 'ndoms_new'
7644 * cpumasks in the array doms_new[] of cpumasks. This compares
7645 * doms_new[] to the current sched domain partitioning, doms_cur[].
7646 * It destroys each deleted domain and builds each new domain.
7648 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
7649 * The masks don't intersect (don't overlap.) We should setup one
7650 * sched domain for each mask. CPUs not in any of the cpumasks will
7651 * not be load balanced. If the same cpumask appears both in the
7652 * current 'doms_cur' domains and in the new 'doms_new', we can leave
7655 * The passed in 'doms_new' should be allocated using
7656 * alloc_sched_domains. This routine takes ownership of it and will
7657 * free_sched_domains it when done with it. If the caller failed the
7658 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
7659 * and partition_sched_domains() will fallback to the single partition
7660 * 'fallback_doms', it also forces the domains to be rebuilt.
7662 * If doms_new == NULL it will be replaced with cpu_online_mask.
7663 * ndoms_new == 0 is a special case for destroying existing domains,
7664 * and it will not create the default domain.
7666 * Call with hotplug lock held
7668 void partition_sched_domains(int ndoms_new
, cpumask_var_t doms_new
[],
7669 struct sched_domain_attr
*dattr_new
)
7674 mutex_lock(&sched_domains_mutex
);
7676 /* always unregister in case we don't destroy any domains */
7677 unregister_sched_domain_sysctl();
7679 /* Let architecture update cpu core mappings. */
7680 new_topology
= arch_update_cpu_topology();
7682 n
= doms_new
? ndoms_new
: 0;
7684 /* Destroy deleted domains */
7685 for (i
= 0; i
< ndoms_cur
; i
++) {
7686 for (j
= 0; j
< n
&& !new_topology
; j
++) {
7687 if (cpumask_equal(doms_cur
[i
], doms_new
[j
])
7688 && dattrs_equal(dattr_cur
, i
, dattr_new
, j
))
7691 /* no match - a current sched domain not in new doms_new[] */
7692 detach_destroy_domains(doms_cur
[i
]);
7697 if (doms_new
== NULL
) {
7699 doms_new
= &fallback_doms
;
7700 cpumask_andnot(doms_new
[0], cpu_active_mask
, cpu_isolated_map
);
7701 WARN_ON_ONCE(dattr_new
);
7704 /* Build new domains */
7705 for (i
= 0; i
< ndoms_new
; i
++) {
7706 for (j
= 0; j
< ndoms_cur
&& !new_topology
; j
++) {
7707 if (cpumask_equal(doms_new
[i
], doms_cur
[j
])
7708 && dattrs_equal(dattr_new
, i
, dattr_cur
, j
))
7711 /* no match - add a new doms_new */
7712 build_sched_domains(doms_new
[i
], dattr_new
? dattr_new
+ i
: NULL
);
7717 /* Remember the new sched domains */
7718 if (doms_cur
!= &fallback_doms
)
7719 free_sched_domains(doms_cur
, ndoms_cur
);
7720 kfree(dattr_cur
); /* kfree(NULL) is safe */
7721 doms_cur
= doms_new
;
7722 dattr_cur
= dattr_new
;
7723 ndoms_cur
= ndoms_new
;
7725 register_sched_domain_sysctl();
7727 mutex_unlock(&sched_domains_mutex
);
7730 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
7731 static void reinit_sched_domains(void)
7735 /* Destroy domains first to force the rebuild */
7736 partition_sched_domains(0, NULL
, NULL
);
7738 rebuild_sched_domains();
7742 static ssize_t
sched_power_savings_store(const char *buf
, size_t count
, int smt
)
7744 unsigned int level
= 0;
7746 if (sscanf(buf
, "%u", &level
) != 1)
7750 * level is always be positive so don't check for
7751 * level < POWERSAVINGS_BALANCE_NONE which is 0
7752 * What happens on 0 or 1 byte write,
7753 * need to check for count as well?
7756 if (level
>= MAX_POWERSAVINGS_BALANCE_LEVELS
)
7760 sched_smt_power_savings
= level
;
7762 sched_mc_power_savings
= level
;
7764 reinit_sched_domains();
7769 #ifdef CONFIG_SCHED_MC
7770 static ssize_t
sched_mc_power_savings_show(struct sysdev_class
*class,
7771 struct sysdev_class_attribute
*attr
,
7774 return sprintf(page
, "%u\n", sched_mc_power_savings
);
7776 static ssize_t
sched_mc_power_savings_store(struct sysdev_class
*class,
7777 struct sysdev_class_attribute
*attr
,
7778 const char *buf
, size_t count
)
7780 return sched_power_savings_store(buf
, count
, 0);
7782 static SYSDEV_CLASS_ATTR(sched_mc_power_savings
, 0644,
7783 sched_mc_power_savings_show
,
7784 sched_mc_power_savings_store
);
7787 #ifdef CONFIG_SCHED_SMT
7788 static ssize_t
sched_smt_power_savings_show(struct sysdev_class
*dev
,
7789 struct sysdev_class_attribute
*attr
,
7792 return sprintf(page
, "%u\n", sched_smt_power_savings
);
7794 static ssize_t
sched_smt_power_savings_store(struct sysdev_class
*dev
,
7795 struct sysdev_class_attribute
*attr
,
7796 const char *buf
, size_t count
)
7798 return sched_power_savings_store(buf
, count
, 1);
7800 static SYSDEV_CLASS_ATTR(sched_smt_power_savings
, 0644,
7801 sched_smt_power_savings_show
,
7802 sched_smt_power_savings_store
);
7805 int __init
sched_create_sysfs_power_savings_entries(struct sysdev_class
*cls
)
7809 #ifdef CONFIG_SCHED_SMT
7811 err
= sysfs_create_file(&cls
->kset
.kobj
,
7812 &attr_sched_smt_power_savings
.attr
);
7814 #ifdef CONFIG_SCHED_MC
7815 if (!err
&& mc_capable())
7816 err
= sysfs_create_file(&cls
->kset
.kobj
,
7817 &attr_sched_mc_power_savings
.attr
);
7821 #endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
7824 * Update cpusets according to cpu_active mask. If cpusets are
7825 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
7826 * around partition_sched_domains().
7828 static int cpuset_cpu_active(struct notifier_block
*nfb
, unsigned long action
,
7831 switch (action
& ~CPU_TASKS_FROZEN
) {
7833 case CPU_DOWN_FAILED
:
7834 cpuset_update_active_cpus();
7841 static int cpuset_cpu_inactive(struct notifier_block
*nfb
, unsigned long action
,
7844 switch (action
& ~CPU_TASKS_FROZEN
) {
7845 case CPU_DOWN_PREPARE
:
7846 cpuset_update_active_cpus();
7853 static int update_runtime(struct notifier_block
*nfb
,
7854 unsigned long action
, void *hcpu
)
7856 int cpu
= (int)(long)hcpu
;
7859 case CPU_DOWN_PREPARE
:
7860 case CPU_DOWN_PREPARE_FROZEN
:
7861 disable_runtime(cpu_rq(cpu
));
7864 case CPU_DOWN_FAILED
:
7865 case CPU_DOWN_FAILED_FROZEN
:
7867 case CPU_ONLINE_FROZEN
:
7868 enable_runtime(cpu_rq(cpu
));
7876 void __init
sched_init_smp(void)
7878 cpumask_var_t non_isolated_cpus
;
7880 alloc_cpumask_var(&non_isolated_cpus
, GFP_KERNEL
);
7881 alloc_cpumask_var(&fallback_doms
, GFP_KERNEL
);
7884 mutex_lock(&sched_domains_mutex
);
7885 init_sched_domains(cpu_active_mask
);
7886 cpumask_andnot(non_isolated_cpus
, cpu_possible_mask
, cpu_isolated_map
);
7887 if (cpumask_empty(non_isolated_cpus
))
7888 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus
);
7889 mutex_unlock(&sched_domains_mutex
);
7892 hotcpu_notifier(cpuset_cpu_active
, CPU_PRI_CPUSET_ACTIVE
);
7893 hotcpu_notifier(cpuset_cpu_inactive
, CPU_PRI_CPUSET_INACTIVE
);
7895 /* RT runtime code needs to handle some hotplug events */
7896 hotcpu_notifier(update_runtime
, 0);
7900 /* Move init over to a non-isolated CPU */
7901 if (set_cpus_allowed_ptr(current
, non_isolated_cpus
) < 0)
7903 sched_init_granularity();
7904 free_cpumask_var(non_isolated_cpus
);
7906 init_sched_rt_class();
7909 void __init
sched_init_smp(void)
7911 sched_init_granularity();
7913 #endif /* CONFIG_SMP */
7915 const_debug
unsigned int sysctl_timer_migration
= 1;
7917 int in_sched_functions(unsigned long addr
)
7919 return in_lock_functions(addr
) ||
7920 (addr
>= (unsigned long)__sched_text_start
7921 && addr
< (unsigned long)__sched_text_end
);
7924 static void init_cfs_rq(struct cfs_rq
*cfs_rq
)
7926 cfs_rq
->tasks_timeline
= RB_ROOT
;
7927 INIT_LIST_HEAD(&cfs_rq
->tasks
);
7928 cfs_rq
->min_vruntime
= (u64
)(-(1LL << 20));
7929 #ifndef CONFIG_64BIT
7930 cfs_rq
->min_vruntime_copy
= cfs_rq
->min_vruntime
;
7934 static void init_rt_rq(struct rt_rq
*rt_rq
, struct rq
*rq
)
7936 struct rt_prio_array
*array
;
7939 array
= &rt_rq
->active
;
7940 for (i
= 0; i
< MAX_RT_PRIO
; i
++) {
7941 INIT_LIST_HEAD(array
->queue
+ i
);
7942 __clear_bit(i
, array
->bitmap
);
7944 /* delimiter for bitsearch: */
7945 __set_bit(MAX_RT_PRIO
, array
->bitmap
);
7947 #if defined CONFIG_SMP
7948 rt_rq
->highest_prio
.curr
= MAX_RT_PRIO
;
7949 rt_rq
->highest_prio
.next
= MAX_RT_PRIO
;
7950 rt_rq
->rt_nr_migratory
= 0;
7951 rt_rq
->overloaded
= 0;
7952 plist_head_init(&rt_rq
->pushable_tasks
);
7956 rt_rq
->rt_throttled
= 0;
7957 rt_rq
->rt_runtime
= 0;
7958 raw_spin_lock_init(&rt_rq
->rt_runtime_lock
);
7961 #ifdef CONFIG_FAIR_GROUP_SCHED
7962 static void init_tg_cfs_entry(struct task_group
*tg
, struct cfs_rq
*cfs_rq
,
7963 struct sched_entity
*se
, int cpu
,
7964 struct sched_entity
*parent
)
7966 struct rq
*rq
= cpu_rq(cpu
);
7971 /* allow initial update_cfs_load() to truncate */
7972 cfs_rq
->load_stamp
= 1;
7975 tg
->cfs_rq
[cpu
] = cfs_rq
;
7978 /* se could be NULL for root_task_group */
7983 se
->cfs_rq
= &rq
->cfs
;
7985 se
->cfs_rq
= parent
->my_q
;
7988 update_load_set(&se
->load
, 0);
7989 se
->parent
= parent
;
7993 #ifdef CONFIG_RT_GROUP_SCHED
7994 static void init_tg_rt_entry(struct task_group
*tg
, struct rt_rq
*rt_rq
,
7995 struct sched_rt_entity
*rt_se
, int cpu
,
7996 struct sched_rt_entity
*parent
)
7998 struct rq
*rq
= cpu_rq(cpu
);
8000 rt_rq
->highest_prio
.curr
= MAX_RT_PRIO
;
8001 rt_rq
->rt_nr_boosted
= 0;
8005 tg
->rt_rq
[cpu
] = rt_rq
;
8006 tg
->rt_se
[cpu
] = rt_se
;
8012 rt_se
->rt_rq
= &rq
->rt
;
8014 rt_se
->rt_rq
= parent
->my_q
;
8016 rt_se
->my_q
= rt_rq
;
8017 rt_se
->parent
= parent
;
8018 INIT_LIST_HEAD(&rt_se
->run_list
);
8022 void __init
sched_init(void)
8025 unsigned long alloc_size
= 0, ptr
;
8027 #ifdef CONFIG_FAIR_GROUP_SCHED
8028 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
8030 #ifdef CONFIG_RT_GROUP_SCHED
8031 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
8033 #ifdef CONFIG_CPUMASK_OFFSTACK
8034 alloc_size
+= num_possible_cpus() * cpumask_size();
8037 ptr
= (unsigned long)kzalloc(alloc_size
, GFP_NOWAIT
);
8039 #ifdef CONFIG_FAIR_GROUP_SCHED
8040 root_task_group
.se
= (struct sched_entity
**)ptr
;
8041 ptr
+= nr_cpu_ids
* sizeof(void **);
8043 root_task_group
.cfs_rq
= (struct cfs_rq
**)ptr
;
8044 ptr
+= nr_cpu_ids
* sizeof(void **);
8046 #endif /* CONFIG_FAIR_GROUP_SCHED */
8047 #ifdef CONFIG_RT_GROUP_SCHED
8048 root_task_group
.rt_se
= (struct sched_rt_entity
**)ptr
;
8049 ptr
+= nr_cpu_ids
* sizeof(void **);
8051 root_task_group
.rt_rq
= (struct rt_rq
**)ptr
;
8052 ptr
+= nr_cpu_ids
* sizeof(void **);
8054 #endif /* CONFIG_RT_GROUP_SCHED */
8055 #ifdef CONFIG_CPUMASK_OFFSTACK
8056 for_each_possible_cpu(i
) {
8057 per_cpu(load_balance_tmpmask
, i
) = (void *)ptr
;
8058 ptr
+= cpumask_size();
8060 #endif /* CONFIG_CPUMASK_OFFSTACK */
8064 init_defrootdomain();
8067 init_rt_bandwidth(&def_rt_bandwidth
,
8068 global_rt_period(), global_rt_runtime());
8070 #ifdef CONFIG_RT_GROUP_SCHED
8071 init_rt_bandwidth(&root_task_group
.rt_bandwidth
,
8072 global_rt_period(), global_rt_runtime());
8073 #endif /* CONFIG_RT_GROUP_SCHED */
8075 #ifdef CONFIG_CGROUP_SCHED
8076 list_add(&root_task_group
.list
, &task_groups
);
8077 INIT_LIST_HEAD(&root_task_group
.children
);
8078 autogroup_init(&init_task
);
8079 #endif /* CONFIG_CGROUP_SCHED */
8081 for_each_possible_cpu(i
) {
8085 raw_spin_lock_init(&rq
->lock
);
8087 rq
->calc_load_active
= 0;
8088 rq
->calc_load_update
= jiffies
+ LOAD_FREQ
;
8089 init_cfs_rq(&rq
->cfs
);
8090 init_rt_rq(&rq
->rt
, rq
);
8091 #ifdef CONFIG_FAIR_GROUP_SCHED
8092 root_task_group
.shares
= root_task_group_load
;
8093 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
8095 * How much cpu bandwidth does root_task_group get?
8097 * In case of task-groups formed thr' the cgroup filesystem, it
8098 * gets 100% of the cpu resources in the system. This overall
8099 * system cpu resource is divided among the tasks of
8100 * root_task_group and its child task-groups in a fair manner,
8101 * based on each entity's (task or task-group's) weight
8102 * (se->load.weight).
8104 * In other words, if root_task_group has 10 tasks of weight
8105 * 1024) and two child groups A0 and A1 (of weight 1024 each),
8106 * then A0's share of the cpu resource is:
8108 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
8110 * We achieve this by letting root_task_group's tasks sit
8111 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
8113 init_tg_cfs_entry(&root_task_group
, &rq
->cfs
, NULL
, i
, NULL
);
8114 #endif /* CONFIG_FAIR_GROUP_SCHED */
8116 rq
->rt
.rt_runtime
= def_rt_bandwidth
.rt_runtime
;
8117 #ifdef CONFIG_RT_GROUP_SCHED
8118 INIT_LIST_HEAD(&rq
->leaf_rt_rq_list
);
8119 init_tg_rt_entry(&root_task_group
, &rq
->rt
, NULL
, i
, NULL
);
8122 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
8123 rq
->cpu_load
[j
] = 0;
8125 rq
->last_load_update_tick
= jiffies
;
8130 rq
->cpu_power
= SCHED_POWER_SCALE
;
8131 rq
->post_schedule
= 0;
8132 rq
->active_balance
= 0;
8133 rq
->next_balance
= jiffies
;
8138 rq
->avg_idle
= 2*sysctl_sched_migration_cost
;
8139 rq_attach_root(rq
, &def_root_domain
);
8141 rq
->nohz_balance_kick
= 0;
8142 init_sched_softirq_csd(&per_cpu(remote_sched_softirq_cb
, i
));
8146 atomic_set(&rq
->nr_iowait
, 0);
8149 set_load_weight(&init_task
);
8151 #ifdef CONFIG_PREEMPT_NOTIFIERS
8152 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
8156 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
);
8159 #ifdef CONFIG_RT_MUTEXES
8160 plist_head_init(&init_task
.pi_waiters
);
8164 * The boot idle thread does lazy MMU switching as well:
8166 atomic_inc(&init_mm
.mm_count
);
8167 enter_lazy_tlb(&init_mm
, current
);
8170 * Make us the idle thread. Technically, schedule() should not be
8171 * called from this thread, however somewhere below it might be,
8172 * but because we are the idle thread, we just pick up running again
8173 * when this runqueue becomes "idle".
8175 init_idle(current
, smp_processor_id());
8177 calc_load_update
= jiffies
+ LOAD_FREQ
;
8180 * During early bootup we pretend to be a normal task:
8182 current
->sched_class
= &fair_sched_class
;
8184 /* Allocate the nohz_cpu_mask if CONFIG_CPUMASK_OFFSTACK */
8185 zalloc_cpumask_var(&nohz_cpu_mask
, GFP_NOWAIT
);
8187 zalloc_cpumask_var(&sched_domains_tmpmask
, GFP_NOWAIT
);
8189 zalloc_cpumask_var(&nohz
.idle_cpus_mask
, GFP_NOWAIT
);
8190 alloc_cpumask_var(&nohz
.grp_idle_mask
, GFP_NOWAIT
);
8191 atomic_set(&nohz
.load_balancer
, nr_cpu_ids
);
8192 atomic_set(&nohz
.first_pick_cpu
, nr_cpu_ids
);
8193 atomic_set(&nohz
.second_pick_cpu
, nr_cpu_ids
);
8195 /* May be allocated at isolcpus cmdline parse time */
8196 if (cpu_isolated_map
== NULL
)
8197 zalloc_cpumask_var(&cpu_isolated_map
, GFP_NOWAIT
);
8200 scheduler_running
= 1;
8203 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
8204 static inline int preempt_count_equals(int preempt_offset
)
8206 int nested
= (preempt_count() & ~PREEMPT_ACTIVE
) + rcu_preempt_depth();
8208 return (nested
== preempt_offset
);
8211 void __might_sleep(const char *file
, int line
, int preempt_offset
)
8213 static unsigned long prev_jiffy
; /* ratelimiting */
8215 if ((preempt_count_equals(preempt_offset
) && !irqs_disabled()) ||
8216 system_state
!= SYSTEM_RUNNING
|| oops_in_progress
)
8218 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
8220 prev_jiffy
= jiffies
;
8223 "BUG: sleeping function called from invalid context at %s:%d\n",
8226 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
8227 in_atomic(), irqs_disabled(),
8228 current
->pid
, current
->comm
);
8230 debug_show_held_locks(current
);
8231 if (irqs_disabled())
8232 print_irqtrace_events(current
);
8235 EXPORT_SYMBOL(__might_sleep
);
8238 #ifdef CONFIG_MAGIC_SYSRQ
8239 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
8241 const struct sched_class
*prev_class
= p
->sched_class
;
8242 int old_prio
= p
->prio
;
8247 deactivate_task(rq
, p
, 0);
8248 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
8250 activate_task(rq
, p
, 0);
8251 resched_task(rq
->curr
);
8254 check_class_changed(rq
, p
, prev_class
, old_prio
);
8257 void normalize_rt_tasks(void)
8259 struct task_struct
*g
, *p
;
8260 unsigned long flags
;
8263 read_lock_irqsave(&tasklist_lock
, flags
);
8264 do_each_thread(g
, p
) {
8266 * Only normalize user tasks:
8271 p
->se
.exec_start
= 0;
8272 #ifdef CONFIG_SCHEDSTATS
8273 p
->se
.statistics
.wait_start
= 0;
8274 p
->se
.statistics
.sleep_start
= 0;
8275 p
->se
.statistics
.block_start
= 0;
8280 * Renice negative nice level userspace
8283 if (TASK_NICE(p
) < 0 && p
->mm
)
8284 set_user_nice(p
, 0);
8288 raw_spin_lock(&p
->pi_lock
);
8289 rq
= __task_rq_lock(p
);
8291 normalize_task(rq
, p
);
8293 __task_rq_unlock(rq
);
8294 raw_spin_unlock(&p
->pi_lock
);
8295 } while_each_thread(g
, p
);
8297 read_unlock_irqrestore(&tasklist_lock
, flags
);
8300 #endif /* CONFIG_MAGIC_SYSRQ */
8302 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
8304 * These functions are only useful for the IA64 MCA handling, or kdb.
8306 * They can only be called when the whole system has been
8307 * stopped - every CPU needs to be quiescent, and no scheduling
8308 * activity can take place. Using them for anything else would
8309 * be a serious bug, and as a result, they aren't even visible
8310 * under any other configuration.
8314 * curr_task - return the current task for a given cpu.
8315 * @cpu: the processor in question.
8317 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
8319 struct task_struct
*curr_task(int cpu
)
8321 return cpu_curr(cpu
);
8324 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
8328 * set_curr_task - set the current task for a given cpu.
8329 * @cpu: the processor in question.
8330 * @p: the task pointer to set.
8332 * Description: This function must only be used when non-maskable interrupts
8333 * are serviced on a separate stack. It allows the architecture to switch the
8334 * notion of the current task on a cpu in a non-blocking manner. This function
8335 * must be called with all CPU's synchronized, and interrupts disabled, the
8336 * and caller must save the original value of the current task (see
8337 * curr_task() above) and restore that value before reenabling interrupts and
8338 * re-starting the system.
8340 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
8342 void set_curr_task(int cpu
, struct task_struct
*p
)
8349 #ifdef CONFIG_FAIR_GROUP_SCHED
8350 static void free_fair_sched_group(struct task_group
*tg
)
8354 for_each_possible_cpu(i
) {
8356 kfree(tg
->cfs_rq
[i
]);
8366 int alloc_fair_sched_group(struct task_group
*tg
, struct task_group
*parent
)
8368 struct cfs_rq
*cfs_rq
;
8369 struct sched_entity
*se
;
8372 tg
->cfs_rq
= kzalloc(sizeof(cfs_rq
) * nr_cpu_ids
, GFP_KERNEL
);
8375 tg
->se
= kzalloc(sizeof(se
) * nr_cpu_ids
, GFP_KERNEL
);
8379 tg
->shares
= NICE_0_LOAD
;
8381 for_each_possible_cpu(i
) {
8382 cfs_rq
= kzalloc_node(sizeof(struct cfs_rq
),
8383 GFP_KERNEL
, cpu_to_node(i
));
8387 se
= kzalloc_node(sizeof(struct sched_entity
),
8388 GFP_KERNEL
, cpu_to_node(i
));
8392 init_cfs_rq(cfs_rq
);
8393 init_tg_cfs_entry(tg
, cfs_rq
, se
, i
, parent
->se
[i
]);
8404 static inline void unregister_fair_sched_group(struct task_group
*tg
, int cpu
)
8406 struct rq
*rq
= cpu_rq(cpu
);
8407 unsigned long flags
;
8410 * Only empty task groups can be destroyed; so we can speculatively
8411 * check on_list without danger of it being re-added.
8413 if (!tg
->cfs_rq
[cpu
]->on_list
)
8416 raw_spin_lock_irqsave(&rq
->lock
, flags
);
8417 list_del_leaf_cfs_rq(tg
->cfs_rq
[cpu
]);
8418 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
8420 #else /* !CONFIG_FAIR_GROUP_SCHED */
8421 static inline void free_fair_sched_group(struct task_group
*tg
)
8426 int alloc_fair_sched_group(struct task_group
*tg
, struct task_group
*parent
)
8431 static inline void unregister_fair_sched_group(struct task_group
*tg
, int cpu
)
8434 #endif /* CONFIG_FAIR_GROUP_SCHED */
8436 #ifdef CONFIG_RT_GROUP_SCHED
8437 static void free_rt_sched_group(struct task_group
*tg
)
8442 destroy_rt_bandwidth(&tg
->rt_bandwidth
);
8444 for_each_possible_cpu(i
) {
8446 kfree(tg
->rt_rq
[i
]);
8448 kfree(tg
->rt_se
[i
]);
8456 int alloc_rt_sched_group(struct task_group
*tg
, struct task_group
*parent
)
8458 struct rt_rq
*rt_rq
;
8459 struct sched_rt_entity
*rt_se
;
8462 tg
->rt_rq
= kzalloc(sizeof(rt_rq
) * nr_cpu_ids
, GFP_KERNEL
);
8465 tg
->rt_se
= kzalloc(sizeof(rt_se
) * nr_cpu_ids
, GFP_KERNEL
);
8469 init_rt_bandwidth(&tg
->rt_bandwidth
,
8470 ktime_to_ns(def_rt_bandwidth
.rt_period
), 0);
8472 for_each_possible_cpu(i
) {
8473 rt_rq
= kzalloc_node(sizeof(struct rt_rq
),
8474 GFP_KERNEL
, cpu_to_node(i
));
8478 rt_se
= kzalloc_node(sizeof(struct sched_rt_entity
),
8479 GFP_KERNEL
, cpu_to_node(i
));
8483 init_rt_rq(rt_rq
, cpu_rq(i
));
8484 rt_rq
->rt_runtime
= tg
->rt_bandwidth
.rt_runtime
;
8485 init_tg_rt_entry(tg
, rt_rq
, rt_se
, i
, parent
->rt_se
[i
]);
8495 #else /* !CONFIG_RT_GROUP_SCHED */
8496 static inline void free_rt_sched_group(struct task_group
*tg
)
8501 int alloc_rt_sched_group(struct task_group
*tg
, struct task_group
*parent
)
8505 #endif /* CONFIG_RT_GROUP_SCHED */
8507 #ifdef CONFIG_CGROUP_SCHED
8508 static void free_sched_group(struct task_group
*tg
)
8510 free_fair_sched_group(tg
);
8511 free_rt_sched_group(tg
);
8516 /* allocate runqueue etc for a new task group */
8517 struct task_group
*sched_create_group(struct task_group
*parent
)
8519 struct task_group
*tg
;
8520 unsigned long flags
;
8522 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
8524 return ERR_PTR(-ENOMEM
);
8526 if (!alloc_fair_sched_group(tg
, parent
))
8529 if (!alloc_rt_sched_group(tg
, parent
))
8532 spin_lock_irqsave(&task_group_lock
, flags
);
8533 list_add_rcu(&tg
->list
, &task_groups
);
8535 WARN_ON(!parent
); /* root should already exist */
8537 tg
->parent
= parent
;
8538 INIT_LIST_HEAD(&tg
->children
);
8539 list_add_rcu(&tg
->siblings
, &parent
->children
);
8540 spin_unlock_irqrestore(&task_group_lock
, flags
);
8545 free_sched_group(tg
);
8546 return ERR_PTR(-ENOMEM
);
8549 /* rcu callback to free various structures associated with a task group */
8550 static void free_sched_group_rcu(struct rcu_head
*rhp
)
8552 /* now it should be safe to free those cfs_rqs */
8553 free_sched_group(container_of(rhp
, struct task_group
, rcu
));
8556 /* Destroy runqueue etc associated with a task group */
8557 void sched_destroy_group(struct task_group
*tg
)
8559 unsigned long flags
;
8562 /* end participation in shares distribution */
8563 for_each_possible_cpu(i
)
8564 unregister_fair_sched_group(tg
, i
);
8566 spin_lock_irqsave(&task_group_lock
, flags
);
8567 list_del_rcu(&tg
->list
);
8568 list_del_rcu(&tg
->siblings
);
8569 spin_unlock_irqrestore(&task_group_lock
, flags
);
8571 /* wait for possible concurrent references to cfs_rqs complete */
8572 call_rcu(&tg
->rcu
, free_sched_group_rcu
);
8575 /* change task's runqueue when it moves between groups.
8576 * The caller of this function should have put the task in its new group
8577 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
8578 * reflect its new group.
8580 void sched_move_task(struct task_struct
*tsk
)
8583 unsigned long flags
;
8586 rq
= task_rq_lock(tsk
, &flags
);
8588 running
= task_current(rq
, tsk
);
8592 dequeue_task(rq
, tsk
, 0);
8593 if (unlikely(running
))
8594 tsk
->sched_class
->put_prev_task(rq
, tsk
);
8596 #ifdef CONFIG_FAIR_GROUP_SCHED
8597 if (tsk
->sched_class
->task_move_group
)
8598 tsk
->sched_class
->task_move_group(tsk
, on_rq
);
8601 set_task_rq(tsk
, task_cpu(tsk
));
8603 if (unlikely(running
))
8604 tsk
->sched_class
->set_curr_task(rq
);
8606 enqueue_task(rq
, tsk
, 0);
8608 task_rq_unlock(rq
, tsk
, &flags
);
8610 #endif /* CONFIG_CGROUP_SCHED */
8612 #ifdef CONFIG_FAIR_GROUP_SCHED
8613 static DEFINE_MUTEX(shares_mutex
);
8615 int sched_group_set_shares(struct task_group
*tg
, unsigned long shares
)
8618 unsigned long flags
;
8621 * We can't change the weight of the root cgroup.
8626 shares
= clamp(shares
, scale_load(MIN_SHARES
), scale_load(MAX_SHARES
));
8628 mutex_lock(&shares_mutex
);
8629 if (tg
->shares
== shares
)
8632 tg
->shares
= shares
;
8633 for_each_possible_cpu(i
) {
8634 struct rq
*rq
= cpu_rq(i
);
8635 struct sched_entity
*se
;
8638 /* Propagate contribution to hierarchy */
8639 raw_spin_lock_irqsave(&rq
->lock
, flags
);
8640 for_each_sched_entity(se
)
8641 update_cfs_shares(group_cfs_rq(se
));
8642 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
8646 mutex_unlock(&shares_mutex
);
8650 unsigned long sched_group_shares(struct task_group
*tg
)
8656 #ifdef CONFIG_RT_GROUP_SCHED
8658 * Ensure that the real time constraints are schedulable.
8660 static DEFINE_MUTEX(rt_constraints_mutex
);
8662 static unsigned long to_ratio(u64 period
, u64 runtime
)
8664 if (runtime
== RUNTIME_INF
)
8667 return div64_u64(runtime
<< 20, period
);
8670 /* Must be called with tasklist_lock held */
8671 static inline int tg_has_rt_tasks(struct task_group
*tg
)
8673 struct task_struct
*g
, *p
;
8675 do_each_thread(g
, p
) {
8676 if (rt_task(p
) && rt_rq_of_se(&p
->rt
)->tg
== tg
)
8678 } while_each_thread(g
, p
);
8683 struct rt_schedulable_data
{
8684 struct task_group
*tg
;
8689 static int tg_schedulable(struct task_group
*tg
, void *data
)
8691 struct rt_schedulable_data
*d
= data
;
8692 struct task_group
*child
;
8693 unsigned long total
, sum
= 0;
8694 u64 period
, runtime
;
8696 period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
8697 runtime
= tg
->rt_bandwidth
.rt_runtime
;
8700 period
= d
->rt_period
;
8701 runtime
= d
->rt_runtime
;
8705 * Cannot have more runtime than the period.
8707 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
8711 * Ensure we don't starve existing RT tasks.
8713 if (rt_bandwidth_enabled() && !runtime
&& tg_has_rt_tasks(tg
))
8716 total
= to_ratio(period
, runtime
);
8719 * Nobody can have more than the global setting allows.
8721 if (total
> to_ratio(global_rt_period(), global_rt_runtime()))
8725 * The sum of our children's runtime should not exceed our own.
8727 list_for_each_entry_rcu(child
, &tg
->children
, siblings
) {
8728 period
= ktime_to_ns(child
->rt_bandwidth
.rt_period
);
8729 runtime
= child
->rt_bandwidth
.rt_runtime
;
8731 if (child
== d
->tg
) {
8732 period
= d
->rt_period
;
8733 runtime
= d
->rt_runtime
;
8736 sum
+= to_ratio(period
, runtime
);
8745 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
8747 struct rt_schedulable_data data
= {
8749 .rt_period
= period
,
8750 .rt_runtime
= runtime
,
8753 return walk_tg_tree(tg_schedulable
, tg_nop
, &data
);
8756 static int tg_set_bandwidth(struct task_group
*tg
,
8757 u64 rt_period
, u64 rt_runtime
)
8761 mutex_lock(&rt_constraints_mutex
);
8762 read_lock(&tasklist_lock
);
8763 err
= __rt_schedulable(tg
, rt_period
, rt_runtime
);
8767 raw_spin_lock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
8768 tg
->rt_bandwidth
.rt_period
= ns_to_ktime(rt_period
);
8769 tg
->rt_bandwidth
.rt_runtime
= rt_runtime
;
8771 for_each_possible_cpu(i
) {
8772 struct rt_rq
*rt_rq
= tg
->rt_rq
[i
];
8774 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
8775 rt_rq
->rt_runtime
= rt_runtime
;
8776 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
8778 raw_spin_unlock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
8780 read_unlock(&tasklist_lock
);
8781 mutex_unlock(&rt_constraints_mutex
);
8786 int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
8788 u64 rt_runtime
, rt_period
;
8790 rt_period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
8791 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
8792 if (rt_runtime_us
< 0)
8793 rt_runtime
= RUNTIME_INF
;
8795 return tg_set_bandwidth(tg
, rt_period
, rt_runtime
);
8798 long sched_group_rt_runtime(struct task_group
*tg
)
8802 if (tg
->rt_bandwidth
.rt_runtime
== RUNTIME_INF
)
8805 rt_runtime_us
= tg
->rt_bandwidth
.rt_runtime
;
8806 do_div(rt_runtime_us
, NSEC_PER_USEC
);
8807 return rt_runtime_us
;
8810 int sched_group_set_rt_period(struct task_group
*tg
, long rt_period_us
)
8812 u64 rt_runtime
, rt_period
;
8814 rt_period
= (u64
)rt_period_us
* NSEC_PER_USEC
;
8815 rt_runtime
= tg
->rt_bandwidth
.rt_runtime
;
8820 return tg_set_bandwidth(tg
, rt_period
, rt_runtime
);
8823 long sched_group_rt_period(struct task_group
*tg
)
8827 rt_period_us
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
8828 do_div(rt_period_us
, NSEC_PER_USEC
);
8829 return rt_period_us
;
8832 static int sched_rt_global_constraints(void)
8834 u64 runtime
, period
;
8837 if (sysctl_sched_rt_period
<= 0)
8840 runtime
= global_rt_runtime();
8841 period
= global_rt_period();
8844 * Sanity check on the sysctl variables.
8846 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
8849 mutex_lock(&rt_constraints_mutex
);
8850 read_lock(&tasklist_lock
);
8851 ret
= __rt_schedulable(NULL
, 0, 0);
8852 read_unlock(&tasklist_lock
);
8853 mutex_unlock(&rt_constraints_mutex
);
8858 int sched_rt_can_attach(struct task_group
*tg
, struct task_struct
*tsk
)
8860 /* Don't accept realtime tasks when there is no way for them to run */
8861 if (rt_task(tsk
) && tg
->rt_bandwidth
.rt_runtime
== 0)
8867 #else /* !CONFIG_RT_GROUP_SCHED */
8868 static int sched_rt_global_constraints(void)
8870 unsigned long flags
;
8873 if (sysctl_sched_rt_period
<= 0)
8877 * There's always some RT tasks in the root group
8878 * -- migration, kstopmachine etc..
8880 if (sysctl_sched_rt_runtime
== 0)
8883 raw_spin_lock_irqsave(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
8884 for_each_possible_cpu(i
) {
8885 struct rt_rq
*rt_rq
= &cpu_rq(i
)->rt
;
8887 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
8888 rt_rq
->rt_runtime
= global_rt_runtime();
8889 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
8891 raw_spin_unlock_irqrestore(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
8895 #endif /* CONFIG_RT_GROUP_SCHED */
8897 int sched_rt_handler(struct ctl_table
*table
, int write
,
8898 void __user
*buffer
, size_t *lenp
,
8902 int old_period
, old_runtime
;
8903 static DEFINE_MUTEX(mutex
);
8906 old_period
= sysctl_sched_rt_period
;
8907 old_runtime
= sysctl_sched_rt_runtime
;
8909 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
8911 if (!ret
&& write
) {
8912 ret
= sched_rt_global_constraints();
8914 sysctl_sched_rt_period
= old_period
;
8915 sysctl_sched_rt_runtime
= old_runtime
;
8917 def_rt_bandwidth
.rt_runtime
= global_rt_runtime();
8918 def_rt_bandwidth
.rt_period
=
8919 ns_to_ktime(global_rt_period());
8922 mutex_unlock(&mutex
);
8927 #ifdef CONFIG_CGROUP_SCHED
8929 /* return corresponding task_group object of a cgroup */
8930 static inline struct task_group
*cgroup_tg(struct cgroup
*cgrp
)
8932 return container_of(cgroup_subsys_state(cgrp
, cpu_cgroup_subsys_id
),
8933 struct task_group
, css
);
8936 static struct cgroup_subsys_state
*
8937 cpu_cgroup_create(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
8939 struct task_group
*tg
, *parent
;
8941 if (!cgrp
->parent
) {
8942 /* This is early initialization for the top cgroup */
8943 return &root_task_group
.css
;
8946 parent
= cgroup_tg(cgrp
->parent
);
8947 tg
= sched_create_group(parent
);
8949 return ERR_PTR(-ENOMEM
);
8955 cpu_cgroup_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
8957 struct task_group
*tg
= cgroup_tg(cgrp
);
8959 sched_destroy_group(tg
);
8963 cpu_cgroup_can_attach_task(struct cgroup
*cgrp
, struct task_struct
*tsk
)
8965 #ifdef CONFIG_RT_GROUP_SCHED
8966 if (!sched_rt_can_attach(cgroup_tg(cgrp
), tsk
))
8969 /* We don't support RT-tasks being in separate groups */
8970 if (tsk
->sched_class
!= &fair_sched_class
)
8977 cpu_cgroup_attach_task(struct cgroup
*cgrp
, struct task_struct
*tsk
)
8979 sched_move_task(tsk
);
8983 cpu_cgroup_exit(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
8984 struct cgroup
*old_cgrp
, struct task_struct
*task
)
8987 * cgroup_exit() is called in the copy_process() failure path.
8988 * Ignore this case since the task hasn't ran yet, this avoids
8989 * trying to poke a half freed task state from generic code.
8991 if (!(task
->flags
& PF_EXITING
))
8994 sched_move_task(task
);
8997 #ifdef CONFIG_FAIR_GROUP_SCHED
8998 static int cpu_shares_write_u64(struct cgroup
*cgrp
, struct cftype
*cftype
,
9001 return sched_group_set_shares(cgroup_tg(cgrp
), scale_load(shareval
));
9004 static u64
cpu_shares_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
)
9006 struct task_group
*tg
= cgroup_tg(cgrp
);
9008 return (u64
) scale_load_down(tg
->shares
);
9010 #endif /* CONFIG_FAIR_GROUP_SCHED */
9012 #ifdef CONFIG_RT_GROUP_SCHED
9013 static int cpu_rt_runtime_write(struct cgroup
*cgrp
, struct cftype
*cft
,
9016 return sched_group_set_rt_runtime(cgroup_tg(cgrp
), val
);
9019 static s64
cpu_rt_runtime_read(struct cgroup
*cgrp
, struct cftype
*cft
)
9021 return sched_group_rt_runtime(cgroup_tg(cgrp
));
9024 static int cpu_rt_period_write_uint(struct cgroup
*cgrp
, struct cftype
*cftype
,
9027 return sched_group_set_rt_period(cgroup_tg(cgrp
), rt_period_us
);
9030 static u64
cpu_rt_period_read_uint(struct cgroup
*cgrp
, struct cftype
*cft
)
9032 return sched_group_rt_period(cgroup_tg(cgrp
));
9034 #endif /* CONFIG_RT_GROUP_SCHED */
9036 static struct cftype cpu_files
[] = {
9037 #ifdef CONFIG_FAIR_GROUP_SCHED
9040 .read_u64
= cpu_shares_read_u64
,
9041 .write_u64
= cpu_shares_write_u64
,
9044 #ifdef CONFIG_RT_GROUP_SCHED
9046 .name
= "rt_runtime_us",
9047 .read_s64
= cpu_rt_runtime_read
,
9048 .write_s64
= cpu_rt_runtime_write
,
9051 .name
= "rt_period_us",
9052 .read_u64
= cpu_rt_period_read_uint
,
9053 .write_u64
= cpu_rt_period_write_uint
,
9058 static int cpu_cgroup_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
9060 return cgroup_add_files(cont
, ss
, cpu_files
, ARRAY_SIZE(cpu_files
));
9063 struct cgroup_subsys cpu_cgroup_subsys
= {
9065 .create
= cpu_cgroup_create
,
9066 .destroy
= cpu_cgroup_destroy
,
9067 .can_attach_task
= cpu_cgroup_can_attach_task
,
9068 .attach_task
= cpu_cgroup_attach_task
,
9069 .exit
= cpu_cgroup_exit
,
9070 .populate
= cpu_cgroup_populate
,
9071 .subsys_id
= cpu_cgroup_subsys_id
,
9075 #endif /* CONFIG_CGROUP_SCHED */
9077 #ifdef CONFIG_CGROUP_CPUACCT
9080 * CPU accounting code for task groups.
9082 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
9083 * (balbir@in.ibm.com).
9086 /* track cpu usage of a group of tasks and its child groups */
9088 struct cgroup_subsys_state css
;
9089 /* cpuusage holds pointer to a u64-type object on every cpu */
9090 u64 __percpu
*cpuusage
;
9091 struct percpu_counter cpustat
[CPUACCT_STAT_NSTATS
];
9092 struct cpuacct
*parent
;
9095 struct cgroup_subsys cpuacct_subsys
;
9097 /* return cpu accounting group corresponding to this container */
9098 static inline struct cpuacct
*cgroup_ca(struct cgroup
*cgrp
)
9100 return container_of(cgroup_subsys_state(cgrp
, cpuacct_subsys_id
),
9101 struct cpuacct
, css
);
9104 /* return cpu accounting group to which this task belongs */
9105 static inline struct cpuacct
*task_ca(struct task_struct
*tsk
)
9107 return container_of(task_subsys_state(tsk
, cpuacct_subsys_id
),
9108 struct cpuacct
, css
);
9111 /* create a new cpu accounting group */
9112 static struct cgroup_subsys_state
*cpuacct_create(
9113 struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
9115 struct cpuacct
*ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
9121 ca
->cpuusage
= alloc_percpu(u64
);
9125 for (i
= 0; i
< CPUACCT_STAT_NSTATS
; i
++)
9126 if (percpu_counter_init(&ca
->cpustat
[i
], 0))
9127 goto out_free_counters
;
9130 ca
->parent
= cgroup_ca(cgrp
->parent
);
9136 percpu_counter_destroy(&ca
->cpustat
[i
]);
9137 free_percpu(ca
->cpuusage
);
9141 return ERR_PTR(-ENOMEM
);
9144 /* destroy an existing cpu accounting group */
9146 cpuacct_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
9148 struct cpuacct
*ca
= cgroup_ca(cgrp
);
9151 for (i
= 0; i
< CPUACCT_STAT_NSTATS
; i
++)
9152 percpu_counter_destroy(&ca
->cpustat
[i
]);
9153 free_percpu(ca
->cpuusage
);
9157 static u64
cpuacct_cpuusage_read(struct cpuacct
*ca
, int cpu
)
9159 u64
*cpuusage
= per_cpu_ptr(ca
->cpuusage
, cpu
);
9162 #ifndef CONFIG_64BIT
9164 * Take rq->lock to make 64-bit read safe on 32-bit platforms.
9166 raw_spin_lock_irq(&cpu_rq(cpu
)->lock
);
9168 raw_spin_unlock_irq(&cpu_rq(cpu
)->lock
);
9176 static void cpuacct_cpuusage_write(struct cpuacct
*ca
, int cpu
, u64 val
)
9178 u64
*cpuusage
= per_cpu_ptr(ca
->cpuusage
, cpu
);
9180 #ifndef CONFIG_64BIT
9182 * Take rq->lock to make 64-bit write safe on 32-bit platforms.
9184 raw_spin_lock_irq(&cpu_rq(cpu
)->lock
);
9186 raw_spin_unlock_irq(&cpu_rq(cpu
)->lock
);
9192 /* return total cpu usage (in nanoseconds) of a group */
9193 static u64
cpuusage_read(struct cgroup
*cgrp
, struct cftype
*cft
)
9195 struct cpuacct
*ca
= cgroup_ca(cgrp
);
9196 u64 totalcpuusage
= 0;
9199 for_each_present_cpu(i
)
9200 totalcpuusage
+= cpuacct_cpuusage_read(ca
, i
);
9202 return totalcpuusage
;
9205 static int cpuusage_write(struct cgroup
*cgrp
, struct cftype
*cftype
,
9208 struct cpuacct
*ca
= cgroup_ca(cgrp
);
9217 for_each_present_cpu(i
)
9218 cpuacct_cpuusage_write(ca
, i
, 0);
9224 static int cpuacct_percpu_seq_read(struct cgroup
*cgroup
, struct cftype
*cft
,
9227 struct cpuacct
*ca
= cgroup_ca(cgroup
);
9231 for_each_present_cpu(i
) {
9232 percpu
= cpuacct_cpuusage_read(ca
, i
);
9233 seq_printf(m
, "%llu ", (unsigned long long) percpu
);
9235 seq_printf(m
, "\n");
9239 static const char *cpuacct_stat_desc
[] = {
9240 [CPUACCT_STAT_USER
] = "user",
9241 [CPUACCT_STAT_SYSTEM
] = "system",
9244 static int cpuacct_stats_show(struct cgroup
*cgrp
, struct cftype
*cft
,
9245 struct cgroup_map_cb
*cb
)
9247 struct cpuacct
*ca
= cgroup_ca(cgrp
);
9250 for (i
= 0; i
< CPUACCT_STAT_NSTATS
; i
++) {
9251 s64 val
= percpu_counter_read(&ca
->cpustat
[i
]);
9252 val
= cputime64_to_clock_t(val
);
9253 cb
->fill(cb
, cpuacct_stat_desc
[i
], val
);
9258 static struct cftype files
[] = {
9261 .read_u64
= cpuusage_read
,
9262 .write_u64
= cpuusage_write
,
9265 .name
= "usage_percpu",
9266 .read_seq_string
= cpuacct_percpu_seq_read
,
9270 .read_map
= cpuacct_stats_show
,
9274 static int cpuacct_populate(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
9276 return cgroup_add_files(cgrp
, ss
, files
, ARRAY_SIZE(files
));
9280 * charge this task's execution time to its accounting group.
9282 * called with rq->lock held.
9284 static void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
)
9289 if (unlikely(!cpuacct_subsys
.active
))
9292 cpu
= task_cpu(tsk
);
9298 for (; ca
; ca
= ca
->parent
) {
9299 u64
*cpuusage
= per_cpu_ptr(ca
->cpuusage
, cpu
);
9300 *cpuusage
+= cputime
;
9307 * When CONFIG_VIRT_CPU_ACCOUNTING is enabled one jiffy can be very large
9308 * in cputime_t units. As a result, cpuacct_update_stats calls
9309 * percpu_counter_add with values large enough to always overflow the
9310 * per cpu batch limit causing bad SMP scalability.
9312 * To fix this we scale percpu_counter_batch by cputime_one_jiffy so we
9313 * batch the same amount of time with CONFIG_VIRT_CPU_ACCOUNTING disabled
9314 * and enabled. We cap it at INT_MAX which is the largest allowed batch value.
9317 #define CPUACCT_BATCH \
9318 min_t(long, percpu_counter_batch * cputime_one_jiffy, INT_MAX)
9320 #define CPUACCT_BATCH 0
9324 * Charge the system/user time to the task's accounting group.
9326 static void cpuacct_update_stats(struct task_struct
*tsk
,
9327 enum cpuacct_stat_index idx
, cputime_t val
)
9330 int batch
= CPUACCT_BATCH
;
9332 if (unlikely(!cpuacct_subsys
.active
))
9339 __percpu_counter_add(&ca
->cpustat
[idx
], val
, batch
);
9345 struct cgroup_subsys cpuacct_subsys
= {
9347 .create
= cpuacct_create
,
9348 .destroy
= cpuacct_destroy
,
9349 .populate
= cpuacct_populate
,
9350 .subsys_id
= cpuacct_subsys_id
,
9352 #endif /* CONFIG_CGROUP_CPUACCT */