/* * kernel/sched.c * * Kernel scheduler and related syscalls * * Copyright (C) 1991-2002 Linus Torvalds * * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and * make semaphores SMP safe * 1998-11-19 Implemented schedule_timeout() and related stuff * by Andrea Arcangeli * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar: * hybrid priority-list and round-robin design with * an array-switch method of distributing timeslices * and per-CPU runqueues. Cleanups and useful suggestions * by Davide Libenzi, preemptible kernel bits by Robert Love. * 2003-09-03 Interactivity tuning by Con Kolivas. * 2004-04-02 Scheduler domains code by Nick Piggin * 2007-04-15 Work begun on replacing all interactivity tuning with a * fair scheduling design by Con Kolivas. * 2007-05-05 Load balancing (smp-nice) and other improvements * by Peter Williams * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Scheduler clock - returns current time in nanosec units. * This is default implementation. * Architectures and sub-architectures can override this. */ unsigned long long __attribute__((weak)) sched_clock(void) { return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ); } /* * Convert user-nice values [ -20 ... 0 ... 19 ] * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ], * and back. */ #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20) #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20) #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio) /* * 'User priority' is the nice value converted to something we * can work with better when scaling various scheduler parameters, * it's a [ 0 ... 39 ] range. */ #define USER_PRIO(p) ((p)-MAX_RT_PRIO) #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio) #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO)) /* * Some helpers for converting nanosecond timing to jiffy resolution */ #define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ)) #define JIFFIES_TO_NS(TIME) ((TIME) * (NSEC_PER_SEC / HZ)) #define NICE_0_LOAD SCHED_LOAD_SCALE #define NICE_0_SHIFT SCHED_LOAD_SHIFT /* * These are the 'tuning knobs' of the scheduler: * * default timeslice is 100 msecs (used only for SCHED_RR tasks). * Timeslices get refilled after they expire. */ #define DEF_TIMESLICE (100 * HZ / 1000) #ifdef CONFIG_SMP /* * Divide a load by a sched group cpu_power : (load / sg->__cpu_power) * Since cpu_power is a 'constant', we can use a reciprocal divide. */ static inline u32 sg_div_cpu_power(const struct sched_group *sg, u32 load) { return reciprocal_divide(load, sg->reciprocal_cpu_power); } /* * Each time a sched group cpu_power is changed, * we must compute its reciprocal value */ static inline void sg_inc_cpu_power(struct sched_group *sg, u32 val) { sg->__cpu_power += val; sg->reciprocal_cpu_power = reciprocal_value(sg->__cpu_power); } #endif static inline int rt_policy(int policy) { if (unlikely(policy == SCHED_FIFO) || unlikely(policy == SCHED_RR)) return 1; return 0; } static inline int task_has_rt_policy(struct task_struct *p) { return rt_policy(p->policy); } /* * This is the priority-queue data structure of the RT scheduling class: */ struct rt_prio_array { DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */ struct list_head queue[MAX_RT_PRIO]; }; #ifdef CONFIG_FAIR_GROUP_SCHED #include struct cfs_rq; /* task group related information */ struct task_group { #ifdef CONFIG_FAIR_CGROUP_SCHED struct cgroup_subsys_state css; #endif /* schedulable entities of this group on each cpu */ struct sched_entity **se; /* runqueue "owned" by this group on each cpu */ struct cfs_rq **cfs_rq; unsigned long shares; /* spinlock to serialize modification to shares */ spinlock_t lock; struct rcu_head rcu; }; /* Default task group's sched entity on each cpu */ static DEFINE_PER_CPU(struct sched_entity, init_sched_entity); /* Default task group's cfs_rq on each cpu */ static DEFINE_PER_CPU(struct cfs_rq, init_cfs_rq) ____cacheline_aligned_in_smp; static struct sched_entity *init_sched_entity_p[NR_CPUS]; static struct cfs_rq *init_cfs_rq_p[NR_CPUS]; /* Default task group. * Every task in system belong to this group at bootup. */ struct task_group init_task_group = { .se = init_sched_entity_p, .cfs_rq = init_cfs_rq_p, }; #ifdef CONFIG_FAIR_USER_SCHED # define INIT_TASK_GRP_LOAD 2*NICE_0_LOAD #else # define INIT_TASK_GRP_LOAD NICE_0_LOAD #endif static int init_task_group_load = INIT_TASK_GRP_LOAD; /* return group to which a task belongs */ static inline struct task_group *task_group(struct task_struct *p) { struct task_group *tg; #ifdef CONFIG_FAIR_USER_SCHED tg = p->user->tg; #elif defined(CONFIG_FAIR_CGROUP_SCHED) tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id), struct task_group, css); #else tg = &init_task_group; #endif return tg; } /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */ static inline void set_task_cfs_rq(struct task_struct *p, unsigned int cpu) { p->se.cfs_rq = task_group(p)->cfs_rq[cpu]; p->se.parent = task_group(p)->se[cpu]; } #else static inline void set_task_cfs_rq(struct task_struct *p, unsigned int cpu) { } #endif /* CONFIG_FAIR_GROUP_SCHED */ /* CFS-related fields in a runqueue */ struct cfs_rq { struct load_weight load; unsigned long nr_running; u64 exec_clock; u64 min_vruntime; struct rb_root tasks_timeline; struct rb_node *rb_leftmost; struct rb_node *rb_load_balance_curr; /* 'curr' points to currently running entity on this cfs_rq. * It is set to NULL otherwise (i.e when none are currently running). */ struct sched_entity *curr; unsigned long nr_spread_over; #ifdef CONFIG_FAIR_GROUP_SCHED struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */ /* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in * a hierarchy). Non-leaf lrqs hold other higher schedulable entities * (like users, containers etc.) * * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This * list is used during load balance. */ struct list_head leaf_cfs_rq_list; /* Better name : task_cfs_rq_list? */ struct task_group *tg; /* group that "owns" this runqueue */ #endif }; /* Real-Time classes' related field in a runqueue: */ struct rt_rq { struct rt_prio_array active; int rt_load_balance_idx; struct list_head *rt_load_balance_head, *rt_load_balance_curr; }; /* * This is the main, per-CPU runqueue data structure. * * Locking rule: those places that want to lock multiple runqueues * (such as the load balancing or the thread migration code), lock * acquire operations must be ordered by ascending &runqueue. */ struct rq { /* runqueue lock: */ spinlock_t lock; /* * nr_running and cpu_load should be in the same cacheline because * remote CPUs use both these fields when doing load calculation. */ unsigned long nr_running; #define CPU_LOAD_IDX_MAX 5 unsigned long cpu_load[CPU_LOAD_IDX_MAX]; unsigned char idle_at_tick; #ifdef CONFIG_NO_HZ unsigned char in_nohz_recently; #endif /* capture load from *all* tasks on this cpu: */ struct load_weight load; unsigned long nr_load_updates; u64 nr_switches; struct cfs_rq cfs; #ifdef CONFIG_FAIR_GROUP_SCHED /* list of leaf cfs_rq on this cpu: */ struct list_head leaf_cfs_rq_list; #endif struct rt_rq rt; /* * This is part of a global counter where only the total sum * over all CPUs matters. A task can increase this counter on * one CPU and if it got migrated afterwards it may decrease * it on another CPU. Always updated under the runqueue lock: */ unsigned long nr_uninterruptible; struct task_struct *curr, *idle; unsigned long next_balance; struct mm_struct *prev_mm; u64 clock, prev_clock_raw; s64 clock_max_delta; unsigned int clock_warps, clock_overflows; u64 idle_clock; unsigned int clock_deep_idle_events; u64 tick_timestamp; atomic_t nr_iowait; #ifdef CONFIG_SMP struct sched_domain *sd; /* For active balancing */ int active_balance; int push_cpu; /* cpu of this runqueue: */ int cpu; struct task_struct *migration_thread; struct list_head migration_queue; #endif #ifdef CONFIG_SCHEDSTATS /* latency stats */ struct sched_info rq_sched_info; /* sys_sched_yield() stats */ unsigned int yld_exp_empty; unsigned int yld_act_empty; unsigned int yld_both_empty; unsigned int yld_count; /* schedule() stats */ unsigned int sched_switch; unsigned int sched_count; unsigned int sched_goidle; /* try_to_wake_up() stats */ unsigned int ttwu_count; unsigned int ttwu_local; /* BKL stats */ unsigned int bkl_count; #endif struct lock_class_key rq_lock_key; }; static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); static DEFINE_MUTEX(sched_hotcpu_mutex); static inline void check_preempt_curr(struct rq *rq, struct task_struct *p) { rq->curr->sched_class->check_preempt_curr(rq, p); } static inline int cpu_of(struct rq *rq) { #ifdef CONFIG_SMP return rq->cpu; #else return 0; #endif } /* * Update the per-runqueue clock, as finegrained as the platform can give * us, but without assuming monotonicity, etc.: */ static void __update_rq_clock(struct rq *rq) { u64 prev_raw = rq->prev_clock_raw; u64 now = sched_clock(); s64 delta = now - prev_raw; u64 clock = rq->clock; #ifdef CONFIG_SCHED_DEBUG WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); #endif /* * Protect against sched_clock() occasionally going backwards: */ if (unlikely(delta < 0)) { clock++; rq->clock_warps++; } else { /* * Catch too large forward jumps too: */ if (unlikely(clock + delta > rq->tick_timestamp + TICK_NSEC)) { if (clock < rq->tick_timestamp + TICK_NSEC) clock = rq->tick_timestamp + TICK_NSEC; else clock++; rq->clock_overflows++; } else { if (unlikely(delta > rq->clock_max_delta)) rq->clock_max_delta = delta; clock += delta; } } rq->prev_clock_raw = now; rq->clock = clock; } static void update_rq_clock(struct rq *rq) { if (likely(smp_processor_id() == cpu_of(rq))) __update_rq_clock(rq); } /* * The domain tree (rq->sd) is protected by RCU's quiescent state transition. * See detach_destroy_domains: synchronize_sched for details. * * The domain tree of any CPU may only be accessed from within * preempt-disabled sections. */ #define for_each_domain(cpu, __sd) \ for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent) #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu))) #define this_rq() (&__get_cpu_var(runqueues)) #define task_rq(p) cpu_rq(task_cpu(p)) #define cpu_curr(cpu) (cpu_rq(cpu)->curr) /* * Tunables that become constants when CONFIG_SCHED_DEBUG is off: */ #ifdef CONFIG_SCHED_DEBUG # define const_debug __read_mostly #else # define const_debug static const #endif /* * Debugging: various feature bits */ enum { SCHED_FEAT_NEW_FAIR_SLEEPERS = 1, SCHED_FEAT_WAKEUP_PREEMPT = 2, SCHED_FEAT_START_DEBIT = 4, SCHED_FEAT_TREE_AVG = 8, SCHED_FEAT_APPROX_AVG = 16, }; const_debug unsigned int sysctl_sched_features = SCHED_FEAT_NEW_FAIR_SLEEPERS * 1 | SCHED_FEAT_WAKEUP_PREEMPT * 1 | SCHED_FEAT_START_DEBIT * 1 | SCHED_FEAT_TREE_AVG * 0 | SCHED_FEAT_APPROX_AVG * 0; #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x) /* * Number of tasks to iterate in a single balance run. * Limited because this is done with IRQs disabled. */ const_debug unsigned int sysctl_sched_nr_migrate = 32; /* * For kernel-internal use: high-speed (but slightly incorrect) per-cpu * clock constructed from sched_clock(): */ unsigned long long cpu_clock(int cpu) { unsigned long long now; unsigned long flags; struct rq *rq; local_irq_save(flags); rq = cpu_rq(cpu); update_rq_clock(rq); now = rq->clock; local_irq_restore(flags); return now; } EXPORT_SYMBOL_GPL(cpu_clock); #ifndef prepare_arch_switch # define prepare_arch_switch(next) do { } while (0) #endif #ifndef finish_arch_switch # define finish_arch_switch(prev) do { } while (0) #endif #ifndef __ARCH_WANT_UNLOCKED_CTXSW static inline int task_running(struct rq *rq, struct task_struct *p) { return rq->curr == p; } static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next) { } static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) { #ifdef CONFIG_DEBUG_SPINLOCK /* this is a valid case when another task releases the spinlock */ rq->lock.owner = current; #endif /* * If we are tracking spinlock dependencies then we have to * fix up the runqueue lock - which gets 'carried over' from * prev into current: */ spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_); spin_unlock_irq(&rq->lock); } #else /* __ARCH_WANT_UNLOCKED_CTXSW */ static inline int task_running(struct rq *rq, struct task_struct *p) { #ifdef CONFIG_SMP return p->oncpu; #else return rq->curr == p; #endif } static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next) { #ifdef CONFIG_SMP /* * We can optimise this out completely for !SMP, because the * SMP rebalancing from interrupt is the only thing that cares * here. */ next->oncpu = 1; #endif #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW spin_unlock_irq(&rq->lock); #else spin_unlock(&rq->lock); #endif } static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) { #ifdef CONFIG_SMP /* * After ->oncpu is cleared, the task can be moved to a different CPU. * We must ensure this doesn't happen until the switch is completely * finished. */ smp_wmb(); prev->oncpu = 0; #endif #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW local_irq_enable(); #endif } #endif /* __ARCH_WANT_UNLOCKED_CTXSW */ /* * __task_rq_lock - lock the runqueue a given task resides on. * Must be called interrupts disabled. */ static inline struct rq *__task_rq_lock(struct task_struct *p) __acquires(rq->lock) { for (;;) { struct rq *rq = task_rq(p); spin_lock(&rq->lock); if (likely(rq == task_rq(p))) return rq; spin_unlock(&rq->lock); } } /* * task_rq_lock - lock the runqueue a given task resides on and disable * interrupts. Note the ordering: we can safely lookup the task_rq without * explicitly disabling preemption. */ static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags) __acquires(rq->lock) { struct rq *rq; for (;;) { local_irq_save(*flags); rq = task_rq(p); spin_lock(&rq->lock); if (likely(rq == task_rq(p))) return rq; spin_unlock_irqrestore(&rq->lock, *flags); } } static void __task_rq_unlock(struct rq *rq) __releases(rq->lock) { spin_unlock(&rq->lock); } static inline void task_rq_unlock(struct rq *rq, unsigned long *flags) __releases(rq->lock) { spin_unlock_irqrestore(&rq->lock, *flags); } /* * this_rq_lock - lock this runqueue and disable interrupts. */ static struct rq *this_rq_lock(void) __acquires(rq->lock) { struct rq *rq; local_irq_disable(); rq = this_rq(); spin_lock(&rq->lock); return rq; } /* * We are going deep-idle (irqs are disabled): */ void sched_clock_idle_sleep_event(void) { struct rq *rq = cpu_rq(smp_processor_id()); spin_lock(&rq->lock); __update_rq_clock(rq); spin_unlock(&rq->lock); rq->clock_deep_idle_events++; } EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event); /* * We just idled delta nanoseconds (called with irqs disabled): */ void sched_clock_idle_wakeup_event(u64 delta_ns) { struct rq *rq = cpu_rq(smp_processor_id()); u64 now = sched_clock(); rq->idle_clock += delta_ns; /* * Override the previous timestamp and ignore all * sched_clock() deltas that occured while we idled, * and use the PM-provided delta_ns to advance the * rq clock: */ spin_lock(&rq->lock); rq->prev_clock_raw = now; rq->clock += delta_ns; spin_unlock(&rq->lock); } EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); /* * resched_task - mark a task 'to be rescheduled now'. * * On UP this means the setting of the need_resched flag, on SMP it * might also involve a cross-CPU call to trigger the scheduler on * the target CPU. */ #ifdef CONFIG_SMP #ifndef tsk_is_polling #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG) #endif static void resched_task(struct task_struct *p) { int cpu; assert_spin_locked(&task_rq(p)->lock); if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED))) return; set_tsk_thread_flag(p, TIF_NEED_RESCHED); cpu = task_cpu(p); if (cpu == smp_processor_id()) return; /* NEED_RESCHED must be visible before we test polling */ smp_mb(); if (!tsk_is_polling(p)) smp_send_reschedule(cpu); } static void resched_cpu(int cpu) { struct rq *rq = cpu_rq(cpu); unsigned long flags; if (!spin_trylock_irqsave(&rq->lock, flags)) return; resched_task(cpu_curr(cpu)); spin_unlock_irqrestore(&rq->lock, flags); } #else static inline void resched_task(struct task_struct *p) { assert_spin_locked(&task_rq(p)->lock); set_tsk_need_resched(p); } #endif #if BITS_PER_LONG == 32 # define WMULT_CONST (~0UL) #else # define WMULT_CONST (1UL << 32) #endif #define WMULT_SHIFT 32 /* * Shift right and round: */ #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y)) static unsigned long calc_delta_mine(unsigned long delta_exec, unsigned long weight, struct load_weight *lw) { u64 tmp; if (unlikely(!lw->inv_weight)) lw->inv_weight = (WMULT_CONST - lw->weight/2) / lw->weight + 1; tmp = (u64)delta_exec * weight; /* * Check whether we'd overflow the 64-bit multiplication: */ if (unlikely(tmp > WMULT_CONST)) tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight, WMULT_SHIFT/2); else tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT); return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX); } static inline unsigned long calc_delta_fair(unsigned long delta_exec, struct load_weight *lw) { return calc_delta_mine(delta_exec, NICE_0_LOAD, lw); } static inline void update_load_add(struct load_weight *lw, unsigned long inc) { lw->weight += inc; } static inline void update_load_sub(struct load_weight *lw, unsigned long dec) { lw->weight -= dec; } /* * To aid in avoiding the subversion of "niceness" due to uneven distribution * of tasks with abnormal "nice" values across CPUs the contribution that * each task makes to its run queue's load is weighted according to its * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a * scaled version of the new time slice allocation that they receive on time * slice expiry etc. */ #define WEIGHT_IDLEPRIO 2 #define WMULT_IDLEPRIO (1 << 31) /* * Nice levels are multiplicative, with a gentle 10% change for every * nice level changed. I.e. when a CPU-bound task goes from nice 0 to * nice 1, it will get ~10% less CPU time than another CPU-bound task * that remained on nice 0. * * The "10% effect" is relative and cumulative: from _any_ nice level, * if you go up 1 level, it's -10% CPU usage, if you go down 1 level * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25. * If a task goes up by ~10% and another task goes down by ~10% then * the relative distance between them is ~25%.) */ static const int prio_to_weight[40] = { /* -20 */ 88761, 71755, 56483, 46273, 36291, /* -15 */ 29154, 23254, 18705, 14949, 11916, /* -10 */ 9548, 7620, 6100, 4904, 3906, /* -5 */ 3121, 2501, 1991, 1586, 1277, /* 0 */ 1024, 820, 655, 526, 423, /* 5 */ 335, 272, 215, 172, 137, /* 10 */ 110, 87, 70, 56, 45, /* 15 */ 36, 29, 23, 18, 15, }; /* * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated. * * In cases where the weight does not change often, we can use the * precalculated inverse to speed up arithmetics by turning divisions * into multiplications: */ static const u32 prio_to_wmult[40] = { /* -20 */ 48388, 59856, 76040, 92818, 118348, /* -15 */ 147320, 184698, 229616, 287308, 360437, /* -10 */ 449829, 563644, 704093, 875809, 1099582, /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326, /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587, /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126, /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717, /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, }; static void activate_task(struct rq *rq, struct task_struct *p, int wakeup); /* * runqueue iterator, to support SMP load-balancing between different * scheduling classes, without having to expose their internal data * structures to the load-balancing proper: */ struct rq_iterator { void *arg; struct task_struct *(*start)(void *); struct task_struct *(*next)(void *); }; #ifdef CONFIG_SMP static unsigned long balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest, unsigned long max_load_move, struct sched_domain *sd, enum cpu_idle_type idle, int *all_pinned, int *this_best_prio, struct rq_iterator *iterator); static int iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest, struct sched_domain *sd, enum cpu_idle_type idle, struct rq_iterator *iterator); #endif #include "sched_stats.h" #include "sched_idletask.c" #include "sched_fair.c" #include "sched_rt.c" #ifdef CONFIG_SCHED_DEBUG # include "sched_debug.c" #endif #define sched_class_highest (&rt_sched_class) /* * Update delta_exec, delta_fair fields for rq. * * delta_fair clock advances at a rate inversely proportional to * total load (rq->load.weight) on the runqueue, while * delta_exec advances at the same rate as wall-clock (provided * cpu is not idle). * * delta_exec / delta_fair is a measure of the (smoothened) load on this * runqueue over any given interval. This (smoothened) load is used * during load balance. * * This function is called /before/ updating rq->load * and when switching tasks. */ static inline void inc_load(struct rq *rq, const struct task_struct *p) { update_load_add(&rq->load, p->se.load.weight); } static inline void dec_load(struct rq *rq, const struct task_struct *p) { update_load_sub(&rq->load, p->se.load.weight); } static void inc_nr_running(struct task_struct *p, struct rq *rq) { rq->nr_running++; inc_load(rq, p); } static void dec_nr_running(struct task_struct *p, struct rq *rq) { rq->nr_running--; dec_load(rq, p); } static void set_load_weight(struct task_struct *p) { if (task_has_rt_policy(p)) { p->se.load.weight = prio_to_weight[0] * 2; p->se.load.inv_weight = prio_to_wmult[0] >> 1; return; } /* * SCHED_IDLE tasks get minimal weight: */ if (p->policy == SCHED_IDLE) { p->se.load.weight = WEIGHT_IDLEPRIO; p->se.load.inv_weight = WMULT_IDLEPRIO; return; } p->se.load.weight = prio_to_weight[p->static_prio - MAX_RT_PRIO]; p->se.load.inv_weight = prio_to_wmult[p->static_prio - MAX_RT_PRIO]; } static void enqueue_task(struct rq *rq, struct task_struct *p, int wakeup) { sched_info_queued(p); p->sched_class->enqueue_task(rq, p, wakeup); p->se.on_rq = 1; } static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep) { p->sched_class->dequeue_task(rq, p, sleep); p->se.on_rq = 0; } /* * __normal_prio - return the priority that is based on the static prio */ static inline int __normal_prio(struct task_struct *p) { return p->static_prio; } /* * Calculate the expected normal priority: i.e. priority * without taking RT-inheritance into account. Might be * boosted by interactivity modifiers. Changes upon fork, * setprio syscalls, and whenever the interactivity * estimator recalculates. */ static inline int normal_prio(struct task_struct *p) { int prio; if (task_has_rt_policy(p)) prio = MAX_RT_PRIO-1 - p->rt_priority; else prio = __normal_prio(p); return prio; } /* * Calculate the current priority, i.e. the priority * taken into account by the scheduler. This value might * be boosted by RT tasks, or might be boosted by * interactivity modifiers. Will be RT if the task got * RT-boosted. If not then it returns p->normal_prio. */ static int effective_prio(struct task_struct *p) { p->normal_prio = normal_prio(p); /* * If we are RT tasks or we were boosted to RT priority, * keep the priority unchanged. Otherwise, update priority * to the normal priority: */ if (!rt_prio(p->prio)) return p->normal_prio; return p->prio; } /* * activate_task - move a task to the runqueue. */ static void activate_task(struct rq *rq, struct task_struct *p, int wakeup) { if (p->state == TASK_UNINTERRUPTIBLE) rq->nr_uninterruptible--; enqueue_task(rq, p, wakeup); inc_nr_running(p, rq); } /* * deactivate_task - remove a task from the runqueue. */ static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep) { if (p->state == TASK_UNINTERRUPTIBLE) rq->nr_uninterruptible++; dequeue_task(rq, p, sleep); dec_nr_running(p, rq); } /** * task_curr - is this task currently executing on a CPU? * @p: the task in question. */ inline int task_curr(const struct task_struct *p) { return cpu_curr(task_cpu(p)) == p; } /* Used instead of source_load when we know the type == 0 */ unsigned long weighted_cpuload(const int cpu) { return cpu_rq(cpu)->load.weight; } static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu) { set_task_cfs_rq(p, cpu); #ifdef CONFIG_SMP /* * After ->cpu is set up to a new value, task_rq_lock(p, ...) can be * successfuly executed on another CPU. We must ensure that updates of * per-task data have been completed by this moment. */ smp_wmb(); task_thread_info(p)->cpu = cpu; #endif } #ifdef CONFIG_SMP /* * Is this task likely cache-hot: */ static inline int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd) { s64 delta; if (p->sched_class != &fair_sched_class) return 0; if (sysctl_sched_migration_cost == -1) return 1; if (sysctl_sched_migration_cost == 0) return 0; delta = now - p->se.exec_start; return delta < (s64)sysctl_sched_migration_cost; } void set_task_cpu(struct task_struct *p, unsigned int new_cpu) { int old_cpu = task_cpu(p); struct rq *old_rq = cpu_rq(old_cpu), *new_rq = cpu_rq(new_cpu); struct cfs_rq *old_cfsrq = task_cfs_rq(p), *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu); u64 clock_offset; clock_offset = old_rq->clock - new_rq->clock; #ifdef CONFIG_SCHEDSTATS if (p->se.wait_start) p->se.wait_start -= clock_offset; if (p->se.sleep_start) p->se.sleep_start -= clock_offset; if (p->se.block_start) p->se.block_start -= clock_offset; if (old_cpu != new_cpu) { schedstat_inc(p, se.nr_migrations); if (task_hot(p, old_rq->clock, NULL)) schedstat_inc(p, se.nr_forced2_migrations); } #endif p->se.vruntime -= old_cfsrq->min_vruntime - new_cfsrq->min_vruntime; __set_task_cpu(p, new_cpu); } struct migration_req { struct list_head list; struct task_struct *task; int dest_cpu; struct completion done; }; /* * The task's runqueue lock must be held. * Returns true if you have to wait for migration thread. */ static int migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req) { struct rq *rq = task_rq(p); /* * If the task is not on a runqueue (and not running), then * it is sufficient to simply update the task's cpu field. */ if (!p->se.on_rq && !task_running(rq, p)) { set_task_cpu(p, dest_cpu); return 0; } init_completion(&req->done); req->task = p; req->dest_cpu = dest_cpu; list_add(&req->list, &rq->migration_queue); return 1; } /* * wait_task_inactive - wait for a thread to unschedule. * * The caller must ensure that the task *will* unschedule sometime soon, * else this function might spin for a *long* time. This function can't * be called with interrupts off, or it may introduce deadlock with * smp_call_function() if an IPI is sent by the same process we are * waiting to become inactive. */ void wait_task_inactive(struct task_struct *p) { unsigned long flags; int running, on_rq; struct rq *rq; for (;;) { /* * We do the initial early heuristics without holding * any task-queue locks at all. We'll only try to get * the runqueue lock when things look like they will * work out! */ rq = task_rq(p); /* * If the task is actively running on another CPU * still, just relax and busy-wait without holding * any locks. * * NOTE! Since we don't hold any locks, it's not * even sure that "rq" stays as the right runqueue! * But we don't care, since "task_running()" will * return false if the runqueue has changed and p * is actually now running somewhere else! */ while (task_running(rq, p)) cpu_relax(); /* * Ok, time to look more closely! We need the rq * lock now, to be *sure*. If we're wrong, we'll * just go back and repeat. */ rq = task_rq_lock(p, &flags); running = task_running(rq, p); on_rq = p->se.on_rq; task_rq_unlock(rq, &flags); /* * Was it really running after all now that we * checked with the proper locks actually held? * * Oops. Go back and try again.. */ if (unlikely(running)) { cpu_relax(); continue; } /* * It's not enough that it's not actively running, * it must be off the runqueue _entirely_, and not * preempted! * * So if it wa still runnable (but just not actively * running right now), it's preempted, and we should * yield - it could be a while. */ if (unlikely(on_rq)) { schedule_timeout_uninterruptible(1); continue; } /* * Ahh, all good. It wasn't running, and it wasn't * runnable, which means that it will never become * running in the future either. We're all done! */ break; } } /*** * kick_process - kick a running thread to enter/exit the kernel * @p: the to-be-kicked thread * * Cause a process which is running on another CPU to enter * kernel-mode, without any delay. (to get signals handled.) * * NOTE: this function doesnt have to take the runqueue lock, * because all it wants to ensure is that the remote task enters * the kernel. If the IPI races and the task has been migrated * to another CPU then no harm is done and the purpose has been * achieved as well. */ void kick_process(struct task_struct *p) { int cpu; preempt_disable(); cpu = task_cpu(p); if ((cpu != smp_processor_id()) && task_curr(p)) smp_send_reschedule(cpu); preempt_enable(); } /* * Return a low guess at the load of a migration-source cpu weighted * according to the scheduling class and "nice" value. * * We want to under-estimate the load of migration sources, to * balance conservatively. */ static unsigned long source_load(int cpu, int type) { struct rq *rq = cpu_rq(cpu); unsigned long total = weighted_cpuload(cpu); if (type == 0) return total; return min(rq->cpu_load[type-1], total); } /* * Return a high guess at the load of a migration-target cpu weighted * according to the scheduling class and "nice" value. */ static unsigned long target_load(int cpu, int type) { struct rq *rq = cpu_rq(cpu); unsigned long total = weighted_cpuload(cpu); if (type == 0) return total; return max(rq->cpu_load[type-1], total); } /* * Return the average load per task on the cpu's run queue */ static inline unsigned long cpu_avg_load_per_task(int cpu) { struct rq *rq = cpu_rq(cpu); unsigned long total = weighted_cpuload(cpu); unsigned long n = rq->nr_running; return n ? total / n : SCHED_LOAD_SCALE; } /* * find_idlest_group finds and returns the least busy CPU group within the * domain. */ static struct sched_group * find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu) { struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups; unsigned long min_load = ULONG_MAX, this_load = 0; int load_idx = sd->forkexec_idx; int imbalance = 100 + (sd->imbalance_pct-100)/2; do { unsigned long load, avg_load; int local_group; int i; /* Skip over this group if it has no CPUs allowed */ if (!cpus_intersects(group->cpumask, p->cpus_allowed)) continue; local_group = cpu_isset(this_cpu, group->cpumask); /* Tally up the load of all CPUs in the group */ avg_load = 0; for_each_cpu_mask(i, group->cpumask) { /* Bias balancing toward cpus of our domain */ if (local_group) load = source_load(i, load_idx); else load = target_load(i, load_idx); avg_load += load; } /* Adjust by relative CPU power of the group */ avg_load = sg_div_cpu_power(group, avg_load * SCHED_LOAD_SCALE); if (local_group) { this_load = avg_load; this = group; } else if (avg_load < min_load) { min_load = avg_load; idlest = group; } } while (group = group->next, group != sd->groups); if (!idlest || 100*this_load < imbalance*min_load) return NULL; return idlest; } /* * find_idlest_cpu - find the idlest cpu among the cpus in group. */ static int find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) { cpumask_t tmp; unsigned long load, min_load = ULONG_MAX; int idlest = -1; int i; /* Traverse only the allowed CPUs */ cpus_and(tmp, group->cpumask, p->cpus_allowed); for_each_cpu_mask(i, tmp) { load = weighted_cpuload(i); if (load < min_load || (load == min_load && i == this_cpu)) { min_load = load; idlest = i; } } return idlest; } /* * sched_balance_self: balance the current task (running on cpu) in domains * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and * SD_BALANCE_EXEC. * * Balance, ie. select the least loaded group. * * Returns the target CPU number, or the same CPU if no balancing is needed. * * preempt must be disabled. */ static int sched_balance_self(int cpu, int flag) { struct task_struct *t = current; struct sched_domain *tmp, *sd = NULL; for_each_domain(cpu, tmp) { /* * If power savings logic is enabled for a domain, stop there. */ if (tmp->flags & SD_POWERSAVINGS_BALANCE) break; if (tmp->flags & flag) sd = tmp; } while (sd) { cpumask_t span; struct sched_group *group; int new_cpu, weight; if (!(sd->flags & flag)) { sd = sd->child; continue; } span = sd->span; group = find_idlest_group(sd, t, cpu); if (!group) { sd = sd->child; continue; } new_cpu = find_idlest_cpu(group, t, cpu); if (new_cpu == -1 || new_cpu == cpu) { /* Now try balancing at a lower domain level of cpu */ sd = sd->child; continue; } /* Now try balancing at a lower domain level of new_cpu */ cpu = new_cpu; sd = NULL; weight = cpus_weight(span); for_each_domain(cpu, tmp) { if (weight <= cpus_weight(tmp->span)) break; if (tmp->flags & flag) sd = tmp; } /* while loop will break here if sd == NULL */ } return cpu; } #endif /* CONFIG_SMP */ /* * wake_idle() will wake a task on an idle cpu if task->cpu is * not idle and an idle cpu is available. The span of cpus to * search starts with cpus closest then further out as needed, * so we always favor a closer, idle cpu. * * Returns the CPU we should wake onto. */ #if defined(ARCH_HAS_SCHED_WAKE_IDLE) static int wake_idle(int cpu, struct task_struct *p) { cpumask_t tmp; struct sched_domain *sd; int i; /* * If it is idle, then it is the best cpu to run this task. * * This cpu is also the best, if it has more than one task already. * Siblings must be also busy(in most cases) as they didn't already * pickup the extra load from this cpu and hence we need not check * sibling runqueue info. This will avoid the checks and cache miss * penalities associated with that. */ if (idle_cpu(cpu) || cpu_rq(cpu)->nr_running > 1) return cpu; for_each_domain(cpu, sd) { if (sd->flags & SD_WAKE_IDLE) { cpus_and(tmp, sd->span, p->cpus_allowed); for_each_cpu_mask(i, tmp) { if (idle_cpu(i)) { if (i != task_cpu(p)) { schedstat_inc(p, se.nr_wakeups_idle); } return i; } } } else { break; } } return cpu; } #else static inline int wake_idle(int cpu, struct task_struct *p) { return cpu; } #endif /*** * try_to_wake_up - wake up a thread * @p: the to-be-woken-up thread * @state: the mask of task states that can be woken * @sync: do a synchronous wakeup? * * Put it on the run-queue if it's not already there. The "current" * thread is always on the run-queue (except when the actual * re-schedule is in progress), and as such you're allowed to do * the simpler "current->state = TASK_RUNNING" to mark yourself * runnable without the overhead of this. * * returns failure only if the task is already active. */ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) { int cpu, orig_cpu, this_cpu, success = 0; unsigned long flags; long old_state; struct rq *rq; #ifdef CONFIG_SMP struct sched_domain *sd, *this_sd = NULL; unsigned long load, this_load; int new_cpu; #endif rq = task_rq_lock(p, &flags); old_state = p->state; if (!(old_state & state)) goto out; if (p->se.on_rq) goto out_running; cpu = task_cpu(p); orig_cpu = cpu; this_cpu = smp_processor_id(); #ifdef CONFIG_SMP if (unlikely(task_running(rq, p))) goto out_activate; new_cpu = cpu; schedstat_inc(rq, ttwu_count); if (cpu == this_cpu) { schedstat_inc(rq, ttwu_local); goto out_set_cpu; } for_each_domain(this_cpu, sd) { if (cpu_isset(cpu, sd->span)) { schedstat_inc(sd, ttwu_wake_remote); this_sd = sd; break; } } if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed))) goto out_set_cpu; /* * Check for affine wakeup and passive balancing possibilities. */ if (this_sd) { int idx = this_sd->wake_idx; unsigned int imbalance; imbalance = 100 + (this_sd->imbalance_pct - 100) / 2; load = source_load(cpu, idx); this_load = target_load(this_cpu, idx); new_cpu = this_cpu; /* Wake to this CPU if we can */ if (this_sd->flags & SD_WAKE_AFFINE) { unsigned long tl = this_load; unsigned long tl_per_task; /* * Attract cache-cold tasks on sync wakeups: */ if (sync && !task_hot(p, rq->clock, this_sd)) goto out_set_cpu; schedstat_inc(p, se.nr_wakeups_affine_attempts); tl_per_task = cpu_avg_load_per_task(this_cpu); /* * If sync wakeup then subtract the (maximum possible) * effect of the currently running task from the load * of the current CPU: */ if (sync) tl -= current->se.load.weight; if ((tl <= load && tl + target_load(cpu, idx) <= tl_per_task) || 100*(tl + p->se.load.weight) <= imbalance*load) { /* * This domain has SD_WAKE_AFFINE and * p is cache cold in this domain, and * there is no bad imbalance. */ schedstat_inc(this_sd, ttwu_move_affine); schedstat_inc(p, se.nr_wakeups_affine); goto out_set_cpu; } } /* * Start passive balancing when half the imbalance_pct * limit is reached. */ if (this_sd->flags & SD_WAKE_BALANCE) { if (imbalance*this_load <= 100*load) { schedstat_inc(this_sd, ttwu_move_balance); schedstat_inc(p, se.nr_wakeups_passive); goto out_set_cpu; } } } new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */ out_set_cpu: new_cpu = wake_idle(new_cpu, p); if (new_cpu != cpu) { set_task_cpu(p, new_cpu); task_rq_unlock(rq, &flags); /* might preempt at this point */ rq = task_rq_lock(p, &flags); old_state = p->state; if (!(old_state & state)) goto out; if (p->se.on_rq) goto out_running; this_cpu = smp_processor_id(); cpu = task_cpu(p); } out_activate: #endif /* CONFIG_SMP */ schedstat_inc(p, se.nr_wakeups); if (sync) schedstat_inc(p, se.nr_wakeups_sync); if (orig_cpu != cpu) schedstat_inc(p, se.nr_wakeups_migrate); if (cpu == this_cpu) schedstat_inc(p, se.nr_wakeups_local); else schedstat_inc(p, se.nr_wakeups_remote); update_rq_clock(rq); activate_task(rq, p, 1); check_preempt_curr(rq, p); success = 1; out_running: p->state = TASK_RUNNING; out: task_rq_unlock(rq, &flags); return success; } int fastcall wake_up_process(struct task_struct *p) { return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED | TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0); } EXPORT_SYMBOL(wake_up_process); int fastcall wake_up_state(struct task_struct *p, unsigned int state) { return try_to_wake_up(p, state, 0); } /* * Perform scheduler related setup for a newly forked process p. * p is forked by current. * * __sched_fork() is basic setup used by init_idle() too: */ static void __sched_fork(struct task_struct *p) { p->se.exec_start = 0; p->se.sum_exec_runtime = 0; p->se.prev_sum_exec_runtime = 0; #ifdef CONFIG_SCHEDSTATS p->se.wait_start = 0; p->se.sum_sleep_runtime = 0; p->se.sleep_start = 0; p->se.block_start = 0; p->se.sleep_max = 0; p->se.block_max = 0; p->se.exec_max = 0; p->se.slice_max = 0; p->se.wait_max = 0; #endif INIT_LIST_HEAD(&p->run_list); p->se.on_rq = 0; #ifdef CONFIG_PREEMPT_NOTIFIERS INIT_HLIST_HEAD(&p->preempt_notifiers); #endif /* * We mark the process as running here, but have not actually * inserted it onto the runqueue yet. This guarantees that * nobody will actually run it, and a signal or other external * event cannot wake it up and insert it on the runqueue either. */ p->state = TASK_RUNNING; } /* * fork()/clone()-time setup: */ void sched_fork(struct task_struct *p, int clone_flags) { int cpu = get_cpu(); __sched_fork(p); #ifdef CONFIG_SMP cpu = sched_balance_self(cpu, SD_BALANCE_FORK); #endif set_task_cpu(p, cpu); /* * Make sure we do not leak PI boosting priority to the child: */ p->prio = current->normal_prio; if (!rt_prio(p->prio)) p->sched_class = &fair_sched_class; #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) if (likely(sched_info_on())) memset(&p->sched_info, 0, sizeof(p->sched_info)); #endif #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) p->oncpu = 0; #endif #ifdef CONFIG_PREEMPT /* Want to start with kernel preemption disabled. */ task_thread_info(p)->preempt_count = 1; #endif put_cpu(); } /* * wake_up_new_task - wake up a newly created task for the first time. * * This function will do some initial scheduler statistics housekeeping * that must be done for every newly created context, then puts the task * on the runqueue and wakes it. */ void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags) { unsigned long flags; struct rq *rq; rq = task_rq_lock(p, &flags); BUG_ON(p->state != TASK_RUNNING); update_rq_clock(rq); p->prio = effective_prio(p); if (!p->sched_class->task_new || !current->se.on_rq) { activate_task(rq, p, 0); } else { /* * Let the scheduling class do new task startup * management (if any): */ p->sched_class->task_new(rq, p); inc_nr_running(p, rq); } check_preempt_curr(rq, p); task_rq_unlock(rq, &flags); } #ifdef CONFIG_PREEMPT_NOTIFIERS /** * preempt_notifier_register - tell me when current is being being preempted & rescheduled * @notifier: notifier struct to register */ void preempt_notifier_register(struct preempt_notifier *notifier) { hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); } EXPORT_SYMBOL_GPL(preempt_notifier_register); /** * preempt_notifier_unregister - no longer interested in preemption notifications * @notifier: notifier struct to unregister * * This is safe to call from within a preemption notifier. */ void preempt_notifier_unregister(struct preempt_notifier *notifier) { hlist_del(¬ifier->link); } EXPORT_SYMBOL_GPL(preempt_notifier_unregister); static void fire_sched_in_preempt_notifiers(struct task_struct *curr) { struct preempt_notifier *notifier; struct hlist_node *node; hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) notifier->ops->sched_in(notifier, raw_smp_processor_id()); } static void fire_sched_out_preempt_notifiers(struct task_struct *curr, struct task_struct *next) { struct preempt_notifier *notifier; struct hlist_node *node; hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) notifier->ops->sched_out(notifier, next); } #else static void fire_sched_in_preempt_notifiers(struct task_struct *curr) { } static void fire_sched_out_preempt_notifiers(struct task_struct *curr, struct task_struct *next) { } #endif /** * prepare_task_switch - prepare to switch tasks * @rq: the runqueue preparing to switch * @prev: the current task that is being switched out * @next: the task we are going to switch to. * * This is called with the rq lock held and interrupts off. It must * be paired with a subsequent finish_task_switch after the context * switch. * * prepare_task_switch sets up locking and calls architecture specific * hooks. */ static inline void prepare_task_switch(struct rq *rq, struct task_struct *prev, struct task_struct *next) { fire_sched_out_preempt_notifiers(prev, next); prepare_lock_switch(rq, next); prepare_arch_switch(next); } /** * finish_task_switch - clean up after a task-switch * @rq: runqueue associated with task-switch * @prev: the thread we just switched away from. * * finish_task_switch must be called after the context switch, paired * with a prepare_task_switch call before the context switch. * finish_task_switch will reconcile locking set up by prepare_task_switch, * and do any other architecture-specific cleanup actions. * * Note that we may have delayed dropping an mm in context_switch(). If * so, we finish that here outside of the runqueue lock. (Doing it * with the lock held can cause deadlocks; see schedule() for * details.) */ static void finish_task_switch(struct rq *rq, struct task_struct *prev) __releases(rq->lock) { struct mm_struct *mm = rq->prev_mm; long prev_state; rq->prev_mm = NULL; /* * A task struct has one reference for the use as "current". * If a task dies, then it sets TASK_DEAD in tsk->state and calls * schedule one last time. The schedule call will never return, and * the scheduled task must drop that reference. * The test for TASK_DEAD must occur while the runqueue locks are * still held, otherwise prev could be scheduled on another cpu, die * there before we look at prev->state, and then the reference would * be dropped twice. * Manfred Spraul */ prev_state = prev->state; finish_arch_switch(prev); finish_lock_switch(rq, prev); fire_sched_in_preempt_notifiers(current); if (mm) mmdrop(mm); if (unlikely(prev_state == TASK_DEAD)) { /* * Remove function-return probe instances associated with this * task and put them back on the free list. */ kprobe_flush_task(prev); put_task_struct(prev); } } /** * schedule_tail - first thing a freshly forked thread must call. * @prev: the thread we just switched away from. */ asmlinkage void schedule_tail(struct task_struct *prev) __releases(rq->lock) { struct rq *rq = this_rq(); finish_task_switch(rq, prev); #ifdef __ARCH_WANT_UNLOCKED_CTXSW /* In this case, finish_task_switch does not reenable preemption */ preempt_enable(); #endif if (current->set_child_tid) put_user(task_pid_vnr(current), current->set_child_tid); } /* * context_switch - switch to the new MM and the new * thread's register state. */ static inline void context_switch(struct rq *rq, struct task_struct *prev, struct task_struct *next) { struct mm_struct *mm, *oldmm; prepare_task_switch(rq, prev, next); mm = next->mm; oldmm = prev->active_mm; /* * For paravirt, this is coupled with an exit in switch_to to * combine the page table reload and the switch backend into * one hypercall. */ arch_enter_lazy_cpu_mode(); if (unlikely(!mm)) { next->active_mm = oldmm; atomic_inc(&oldmm->mm_count); enter_lazy_tlb(oldmm, next); } else switch_mm(oldmm, mm, next); if (unlikely(!prev->mm)) { prev->active_mm = NULL; rq->prev_mm = oldmm; } /* * Since the runqueue lock will be released by the next * task (which is an invalid locking op but in the case * of the scheduler it's an obvious special-case), so we * do an early lockdep release here: */ #ifndef __ARCH_WANT_UNLOCKED_CTXSW spin_release(&rq->lock.dep_map, 1, _THIS_IP_); #endif /* Here we just switch the register state and the stack. */ switch_to(prev, next, prev); barrier(); /* * this_rq must be evaluated again because prev may have moved * CPUs since it called schedule(), thus the 'rq' on its stack * frame will be invalid. */ finish_task_switch(this_rq(), prev); } /* * nr_running, nr_uninterruptible and nr_context_switches: * * externally visible scheduler statistics: current number of runnable * threads, current number of uninterruptible-sleeping threads, total * number of context switches performed since bootup. */ unsigned long nr_running(void) { unsigned long i, sum = 0; for_each_online_cpu(i) sum += cpu_rq(i)->nr_running; return sum; } unsigned long nr_uninterruptible(void) { unsigned long i, sum = 0; for_each_possible_cpu(i) sum += cpu_rq(i)->nr_uninterruptible; /* * Since we read the counters lockless, it might be slightly * inaccurate. Do not allow it to go below zero though: */ if (unlikely((long)sum < 0)) sum = 0; return sum; } unsigned long long nr_context_switches(void) { int i; unsigned long long sum = 0; for_each_possible_cpu(i) sum += cpu_rq(i)->nr_switches; return sum; } unsigned long nr_iowait(void) { unsigned long i, sum = 0; for_each_possible_cpu(i) sum += atomic_read(&cpu_rq(i)->nr_iowait); return sum; } unsigned long nr_active(void) { unsigned long i, running = 0, uninterruptible = 0; for_each_online_cpu(i) { running += cpu_rq(i)->nr_running; uninterruptible += cpu_rq(i)->nr_uninterruptible; } if (unlikely((long)uninterruptible < 0)) uninterruptible = 0; return running + uninterruptible; } /* * Update rq->cpu_load[] statistics. This function is usually called every * scheduler tick (TICK_NSEC). */ static void update_cpu_load(struct rq *this_rq) { unsigned long this_load = this_rq->load.weight; int i, scale; this_rq->nr_load_updates++; /* Update our load: */ for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) { unsigned long old_load, new_load; /* scale is effectively 1 << i now, and >> i divides by scale */ old_load = this_rq->cpu_load[i]; new_load = this_load; /* * Round up the averaging division if load is increasing. This * prevents us from getting stuck on 9 if the load is 10, for * example. */ if (new_load > old_load) new_load += scale-1; this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i; } } #ifdef CONFIG_SMP /* * double_rq_lock - safely lock two runqueues * * Note this does not disable interrupts like task_rq_lock, * you need to do so manually before calling. */ static void double_rq_lock(struct rq *rq1, struct rq *rq2) __acquires(rq1->lock) __acquires(rq2->lock) { BUG_ON(!irqs_disabled()); if (rq1 == rq2) { spin_lock(&rq1->lock); __acquire(rq2->lock); /* Fake it out ;) */ } else { if (rq1 < rq2) { spin_lock(&rq1->lock); spin_lock(&rq2->lock); } else { spin_lock(&rq2->lock); spin_lock(&rq1->lock); } } update_rq_clock(rq1); update_rq_clock(rq2); } /* * double_rq_unlock - safely unlock two runqueues * * Note this does not restore interrupts like task_rq_unlock, * you need to do so manually after calling. */ static void double_rq_unlock(struct rq *rq1, struct rq *rq2) __releases(rq1->lock) __releases(rq2->lock) { spin_unlock(&rq1->lock); if (rq1 != rq2) spin_unlock(&rq2->lock); else __release(rq2->lock); } /* * double_lock_balance - lock the busiest runqueue, this_rq is locked already. */ static void double_lock_balance(struct rq *this_rq, struct rq *busiest) __releases(this_rq->lock) __acquires(busiest->lock) __acquires(this_rq->lock) { if (unlikely(!irqs_disabled())) { /* printk() doesn't work good under rq->lock */ spin_unlock(&this_rq->lock); BUG_ON(1); } if (unlikely(!spin_trylock(&busiest->lock))) { if (busiest < this_rq) { spin_unlock(&this_rq->lock); spin_lock(&busiest->lock); spin_lock(&this_rq->lock); } else spin_lock(&busiest->lock); } } /* * If dest_cpu is allowed for this process, migrate the task to it. * This is accomplished by forcing the cpu_allowed mask to only * allow dest_cpu, which will force the cpu onto dest_cpu. Then * the cpu_allowed mask is restored. */ static void sched_migrate_task(struct task_struct *p, int dest_cpu) { struct migration_req req; unsigned long flags; struct rq *rq; rq = task_rq_lock(p, &flags); if (!cpu_isset(dest_cpu, p->cpus_allowed) || unlikely(cpu_is_offline(dest_cpu))) goto out; /* force the process onto the specified CPU */ if (migrate_task(p, dest_cpu, &req)) { /* Need to wait for migration thread (might exit: take ref). */ struct task_struct *mt = rq->migration_thread; get_task_struct(mt); task_rq_unlock(rq, &flags); wake_up_process(mt); put_task_struct(mt); wait_for_completion(&req.done); return; } out: task_rq_unlock(rq, &flags); } /* * sched_exec - execve() is a valuable balancing opportunity, because at * this point the task has the smallest effective memory and cache footprint. */ void sched_exec(void) { int new_cpu, this_cpu = get_cpu(); new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC); put_cpu(); if (new_cpu != this_cpu) sched_migrate_task(current, new_cpu); } /* * pull_task - move a task from a remote runqueue to the local runqueue. * Both runqueues must be locked. */ static void pull_task(struct rq *src_rq, struct task_struct *p, struct rq *this_rq, int this_cpu) { deactivate_task(src_rq, p, 0); set_task_cpu(p, this_cpu); activate_task(this_rq, p, 0); /* * Note that idle threads have a prio of MAX_PRIO, for this test * to be always true for them. */ check_preempt_curr(this_rq, p); } /* * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? */ static int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, struct sched_domain *sd, enum cpu_idle_type idle, int *all_pinned) { /* * We do not migrate tasks that are: * 1) running (obviously), or * 2) cannot be migrated to this CPU due to cpus_allowed, or * 3) are cache-hot on their current CPU. */ if (!cpu_isset(this_cpu, p->cpus_allowed)) { schedstat_inc(p, se.nr_failed_migrations_affine); return 0; } *all_pinned = 0; if (task_running(rq, p)) { schedstat_inc(p, se.nr_failed_migrations_running); return 0; } /* * Aggressive migration if: * 1) task is cache cold, or * 2) too many balance attempts have failed. */ if (!task_hot(p, rq->clock, sd) || sd->nr_balance_failed > sd->cache_nice_tries) { #ifdef CONFIG_SCHEDSTATS if (task_hot(p, rq->clock, sd)) { schedstat_inc(sd, lb_hot_gained[idle]); schedstat_inc(p, se.nr_forced_migrations); } #endif return 1; } if (task_hot(p, rq->clock, sd)) { schedstat_inc(p, se.nr_failed_migrations_hot); return 0; } return 1; } static unsigned long balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest, unsigned long max_load_move, struct sched_domain *sd, enum cpu_idle_type idle, int *all_pinned, int *this_best_prio, struct rq_iterator *iterator) { int loops = 0, pulled = 0, pinned = 0, skip_for_load; struct task_struct *p; long rem_load_move = max_load_move; if (max_load_move == 0) goto out; pinned = 1; /* * Start the load-balancing iterator: */ p = iterator->start(iterator->arg); next: if (!p || loops++ > sysctl_sched_nr_migrate) goto out; /* * To help distribute high priority tasks across CPUs we don't * skip a task if it will be the highest priority task (i.e. smallest * prio value) on its new queue regardless of its load weight */ skip_for_load = (p->se.load.weight >> 1) > rem_load_move + SCHED_LOAD_SCALE_FUZZ; if ((skip_for_load && p->prio >= *this_best_prio) || !can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) { p = iterator->next(iterator->arg); goto next; } pull_task(busiest, p, this_rq, this_cpu); pulled++; rem_load_move -= p->se.load.weight; /* * We only want to steal up to the prescribed amount of weighted load. */ if (rem_load_move > 0) { if (p->prio < *this_best_prio) *this_best_prio = p->prio; p = iterator->next(iterator->arg); goto next; } out: /* * Right now, this is one of only two places pull_task() is called, * so we can safely collect pull_task() stats here rather than * inside pull_task(). */ schedstat_add(sd, lb_gained[idle], pulled); if (all_pinned) *all_pinned = pinned; return max_load_move - rem_load_move; } /* * move_tasks tries to move up to max_load_move weighted load from busiest to * this_rq, as part of a balancing operation within domain "sd". * Returns 1 if successful and 0 otherwise. * * Called with both runqueues locked. */ static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest, unsigned long max_load_move, struct sched_domain *sd, enum cpu_idle_type idle, int *all_pinned) { const struct sched_class *class = sched_class_highest; unsigned long total_load_moved = 0; int this_best_prio = this_rq->curr->prio; do { total_load_moved += class->load_balance(this_rq, this_cpu, busiest, max_load_move - total_load_moved, sd, idle, all_pinned, &this_best_prio); class = class->next; } while (class && max_load_move > total_load_moved); return total_load_moved > 0; } static int iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest, struct sched_domain *sd, enum cpu_idle_type idle, struct rq_iterator *iterator) { struct task_struct *p = iterator->start(iterator->arg); int pinned = 0; while (p) { if (can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) { pull_task(busiest, p, this_rq, this_cpu); /* * Right now, this is only the second place pull_task() * is called, so we can safely collect pull_task() * stats here rather than inside pull_task(). */ schedstat_inc(sd, lb_gained[idle]); return 1; } p = iterator->next(iterator->arg); } return 0; } /* * move_one_task tries to move exactly one task from busiest to this_rq, as * part of active balancing operations within "domain". * Returns 1 if successful and 0 otherwise. * * Called with both runqueues locked. */ static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest, struct sched_domain *sd, enum cpu_idle_type idle) { const struct sched_class *class; for (class = sched_class_highest; class; class = class->next) if (class->move_one_task(this_rq, this_cpu, busiest, sd, idle)) return 1; return 0; } /* * find_busiest_group finds and returns the busiest CPU group within the * domain. It calculates and returns the amount of weighted load which * should be moved to restore balance via the imbalance parameter. */ static struct sched_group * find_busiest_group(struct sched_domain *sd, int this_cpu, unsigned long *imbalance, enum cpu_idle_type idle, int *sd_idle, cpumask_t *cpus, int *balance) { struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups; unsigned long max_load, avg_load, total_load, this_load, total_pwr; unsigned long max_pull; unsigned long busiest_load_per_task, busiest_nr_running; unsigned long this_load_per_task, this_nr_running; int load_idx, group_imb = 0; #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) int power_savings_balance = 1; unsigned long leader_nr_running = 0, min_load_per_task = 0; unsigned long min_nr_running = ULONG_MAX; struct sched_group *group_min = NULL, *group_leader = NULL; #endif max_load = this_load = total_load = total_pwr = 0; busiest_load_per_task = busiest_nr_running = 0; this_load_per_task = this_nr_running = 0; if (idle == CPU_NOT_IDLE) load_idx = sd->busy_idx; else if (idle == CPU_NEWLY_IDLE) load_idx = sd->newidle_idx; else load_idx = sd->idle_idx; do { unsigned long load, group_capacity, max_cpu_load, min_cpu_load; int local_group; int i; int __group_imb = 0; unsigned int balance_cpu = -1, first_idle_cpu = 0; unsigned long sum_nr_running, sum_weighted_load; local_group = cpu_isset(this_cpu, group->cpumask); if (local_group) balance_cpu = first_cpu(group->cpumask); /* Tally up the load of all CPUs in the group */ sum_weighted_load = sum_nr_running = avg_load = 0; max_cpu_load = 0; min_cpu_load = ~0UL; for_each_cpu_mask(i, group->cpumask) { struct rq *rq; if (!cpu_isset(i, *cpus)) continue; rq = cpu_rq(i); if (*sd_idle && rq->nr_running) *sd_idle = 0; /* Bias balancing toward cpus of our domain */ if (local_group) { if (idle_cpu(i) && !first_idle_cpu) { first_idle_cpu = 1; balance_cpu = i; } load = target_load(i, load_idx); } else { load = source_load(i, load_idx); if (load > max_cpu_load) max_cpu_load = load; if (min_cpu_load > load) min_cpu_load = load; } avg_load += load; sum_nr_running += rq->nr_running; sum_weighted_load += weighted_cpuload(i); } /* * First idle cpu or the first cpu(busiest) in this sched group * is eligible for doing load balancing at this and above * domains. In the newly idle case, we will allow all the cpu's * to do the newly idle load balance. */ if (idle != CPU_NEWLY_IDLE && local_group && balance_cpu != this_cpu && balance) { *balance = 0; goto ret; } total_load += avg_load; total_pwr += group->__cpu_power; /* Adjust by relative CPU power of the group */ avg_load = sg_div_cpu_power(group, avg_load * SCHED_LOAD_SCALE); if ((max_cpu_load - min_cpu_load) > SCHED_LOAD_SCALE) __group_imb = 1; group_capacity = group->__cpu_power / SCHED_LOAD_SCALE; if (local_group) { this_load = avg_load; this = group; this_nr_running = sum_nr_running; this_load_per_task = sum_weighted_load; } else if (avg_load > max_load && (sum_nr_running > group_capacity || __group_imb)) { max_load = avg_load; busiest = group; busiest_nr_running = sum_nr_running; busiest_load_per_task = sum_weighted_load; group_imb = __group_imb; } #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) /* * Busy processors will not participate in power savings * balance. */ if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE)) goto group_next; /* * If the local group is idle or completely loaded * no need to do power savings balance at this domain */ if (local_group && (this_nr_running >= group_capacity || !this_nr_running)) power_savings_balance = 0; /* * If a group is already running at full capacity or idle, * don't include that group in power savings calculations */ if (!power_savings_balance || sum_nr_running >= group_capacity || !sum_nr_running) goto group_next; /* * Calculate the group which has the least non-idle load. * This is the group from where we need to pick up the load * for saving power */ if ((sum_nr_running < min_nr_running) || (sum_nr_running == min_nr_running && first_cpu(group->cpumask) < first_cpu(group_min->cpumask))) { group_min = group; min_nr_running = sum_nr_running; min_load_per_task = sum_weighted_load / sum_nr_running; } /* * Calculate the group which is almost near its * capacity but still has some space to pick up some load * from other group and save more power */ if (sum_nr_running <= group_capacity - 1) { if (sum_nr_running > leader_nr_running || (sum_nr_running == leader_nr_running && first_cpu(group->cpumask) > first_cpu(group_leader->cpumask))) { group_leader = group; leader_nr_running = sum_nr_running; } } group_next: #endif group = group->next; } while (group != sd->groups); if (!busiest || this_load >= max_load || busiest_nr_running == 0) goto out_balanced; avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr; if (this_load >= avg_load || 100*max_load <= sd->imbalance_pct*this_load) goto out_balanced; busiest_load_per_task /= busiest_nr_running; if (group_imb) busiest_load_per_task = min(busiest_load_per_task, avg_load); /* * We're trying to get all the cpus to the average_load, so we don't * want to push ourselves above the average load, nor do we wish to * reduce the max loaded cpu below the average load, as either of these * actions would just result in more rebalancing later, and ping-pong * tasks around. Thus we look for the minimum possible imbalance. * Negative imbalances (*we* are more loaded than anyone else) will * be counted as no imbalance for these purposes -- we can't fix that * by pulling tasks to us. Be careful of negative numbers as they'll * appear as very large values with unsigned longs. */ if (max_load <= busiest_load_per_task) goto out_balanced; /* * In the presence of smp nice balancing, certain scenarios can have * max load less than avg load(as we skip the groups at or below * its cpu_power, while calculating max_load..) */ if (max_load < avg_load) { *imbalance = 0; goto small_imbalance; } /* Don't want to pull so many tasks that a group would go idle */ max_pull = min(max_load - avg_load, max_load - busiest_load_per_task); /* How much load to actually move to equalise the imbalance */ *imbalance = min(max_pull * busiest->__cpu_power, (avg_load - this_load) * this->__cpu_power) / SCHED_LOAD_SCALE; /* * if *imbalance is less than the average load per runnable task * there is no gaurantee that any tasks will be moved so we'll have * a think about bumping its value to force at least one task to be * moved */ if (*imbalance < busiest_load_per_task) { unsigned long tmp, pwr_now, pwr_move; unsigned int imbn; small_imbalance: pwr_move = pwr_now = 0; imbn = 2; if (this_nr_running) { this_load_per_task /= this_nr_running; if (busiest_load_per_task > this_load_per_task) imbn = 1; } else this_load_per_task = SCHED_LOAD_SCALE; if (max_load - this_load + SCHED_LOAD_SCALE_FUZZ >= busiest_load_per_task * imbn) { *imbalance = busiest_load_per_task; return busiest; } /* * OK, we don't have enough imbalance to justify moving tasks, * however we may be able to increase total CPU power used by * moving them. */ pwr_now += busiest->__cpu_power * min(busiest_load_per_task, max_load); pwr_now += this->__cpu_power * min(this_load_per_task, this_load); pwr_now /= SCHED_LOAD_SCALE; /* Amount of load we'd subtract */ tmp = sg_div_cpu_power(busiest, busiest_load_per_task * SCHED_LOAD_SCALE); if (max_load > tmp) pwr_move += busiest->__cpu_power * min(busiest_load_per_task, max_load - tmp); /* Amount of load we'd add */ if (max_load * busiest->__cpu_power < busiest_load_per_task * SCHED_LOAD_SCALE) tmp = sg_div_cpu_power(this, max_load * busiest->__cpu_power); else tmp = sg_div_cpu_power(this, busiest_load_per_task * SCHED_LOAD_SCALE); pwr_move += this->__cpu_power * min(this_load_per_task, this_load + tmp); pwr_move /= SCHED_LOAD_SCALE; /* Move if we gain throughput */ if (pwr_move > pwr_now) *imbalance = busiest_load_per_task; } return busiest; out_balanced: #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE)) goto ret; if (this == group_leader && group_leader != group_min) { *imbalance = min_load_per_task; return group_min; } #endif ret: *imbalance = 0; return NULL; } /* * find_busiest_queue - find the busiest runqueue among the cpus in group. */ static struct rq * find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle, unsigned long imbalance, cpumask_t *cpus) { struct rq *busiest = NULL, *rq; unsigned long max_load = 0; int i; for_each_cpu_mask(i, group->cpumask) { unsigned long wl; if (!cpu_isset(i, *cpus)) continue; rq = cpu_rq(i); wl = weighted_cpuload(i); if (rq->nr_running == 1 && wl > imbalance) continue; if (wl > max_load) { max_load = wl; busiest = rq; } } return busiest; } /* * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but * so long as it is large enough. */ #define MAX_PINNED_INTERVAL 512 /* * Check this_cpu to ensure it is balanced within domain. Attempt to move * tasks if there is an imbalance. */ static int load_balance(int this_cpu, struct rq *this_rq, struct sched_domain *sd, enum cpu_idle_type idle, int *balance) { int ld_moved, all_pinned = 0, active_balance = 0, sd_idle = 0; struct sched_group *group; unsigned long imbalance; struct rq *busiest; cpumask_t cpus = CPU_MASK_ALL; unsigned long flags; /* * When power savings policy is enabled for the parent domain, idle * sibling can pick up load irrespective of busy siblings. In this case, * let the state of idle sibling percolate up as CPU_IDLE, instead of * portraying it as CPU_NOT_IDLE. */ if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER && !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) sd_idle = 1; schedstat_inc(sd, lb_count[idle]); redo: group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle, &cpus, balance); if (*balance == 0) goto out_balanced; if (!group) { schedstat_inc(sd, lb_nobusyg[idle]); goto out_balanced; } busiest = find_busiest_queue(group, idle, imbalance, &cpus); if (!busiest) { schedstat_inc(sd, lb_nobusyq[idle]); goto out_balanced; } BUG_ON(busiest == this_rq); schedstat_add(sd, lb_imbalance[idle], imbalance); ld_moved = 0; if (busiest->nr_running > 1) { /* * Attempt to move tasks. If find_busiest_group has found * an imbalance but busiest->nr_running <= 1, the group is * still unbalanced. ld_moved simply stays zero, so it is * correctly treated as an imbalance. */ local_irq_save(flags); double_rq_lock(this_rq, busiest); ld_moved = move_tasks(this_rq, this_cpu, busiest, imbalance, sd, idle, &all_pinned); double_rq_unlock(this_rq, busiest); local_irq_restore(flags); /* * some other cpu did the load balance for us. */ if (ld_moved && this_cpu != smp_processor_id()) resched_cpu(this_cpu); /* All tasks on this runqueue were pinned by CPU affinity */ if (unlikely(all_pinned)) { cpu_clear(cpu_of(busiest), cpus); if (!cpus_empty(cpus)) goto redo; goto out_balanced; } } if (!ld_moved) { schedstat_inc(sd, lb_failed[idle]); sd->nr_balance_failed++; if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) { spin_lock_irqsave(&busiest->lock, flags); /* don't kick the migration_thread, if the curr * task on busiest cpu can't be moved to this_cpu */ if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) { spin_unlock_irqrestore(&busiest->lock, flags); all_pinned = 1; goto out_one_pinned; } if (!busiest->active_balance) { busiest->active_balance = 1; busiest->push_cpu = this_cpu; active_balance = 1; } spin_unlock_irqrestore(&busiest->lock, flags); if (active_balance) wake_up_process(busiest->migration_thread); /* * We've kicked active balancing, reset the failure * counter. */ sd->nr_balance_failed = sd->cache_nice_tries+1; } } else sd->nr_balance_failed = 0; if (likely(!active_balance)) { /* We were unbalanced, so reset the balancing interval */ sd->balance_interval = sd->min_interval; } else { /* * If we've begun active balancing, start to back off. This * case may not be covered by the all_pinned logic if there * is only 1 task on the busy runqueue (because we don't call * move_tasks). */ if (sd->balance_interval < sd->max_interval) sd->balance_interval *= 2; } if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER && !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) return -1; return ld_moved; out_balanced: schedstat_inc(sd, lb_balanced[idle]); sd->nr_balance_failed = 0; out_one_pinned: /* tune up the balancing interval */ if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) || (sd->balance_interval < sd->max_interval)) sd->balance_interval *= 2; if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER && !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) return -1; return 0; } /* * Check this_cpu to ensure it is balanced within domain. Attempt to move * tasks if there is an imbalance. * * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE). * this_rq is locked. */ static int load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd) { struct sched_group *group; struct rq *busiest = NULL; unsigned long imbalance; int ld_moved = 0; int sd_idle = 0; int all_pinned = 0; cpumask_t cpus = CPU_MASK_ALL; /* * When power savings policy is enabled for the parent domain, idle * sibling can pick up load irrespective of busy siblings. In this case, * let the state of idle sibling percolate up as IDLE, instead of * portraying it as CPU_NOT_IDLE. */ if (sd->flags & SD_SHARE_CPUPOWER && !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) sd_idle = 1; schedstat_inc(sd, lb_count[CPU_NEWLY_IDLE]); redo: group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE, &sd_idle, &cpus, NULL); if (!group) { schedstat_inc(sd, lb_nobusyg[CPU_NEWLY_IDLE]); goto out_balanced; } busiest = find_busiest_queue(group, CPU_NEWLY_IDLE, imbalance, &cpus); if (!busiest) { schedstat_inc(sd, lb_nobusyq[CPU_NEWLY_IDLE]); goto out_balanced; } BUG_ON(busiest == this_rq); schedstat_add(sd, lb_imbalance[CPU_NEWLY_IDLE], imbalance); ld_moved = 0; if (busiest->nr_running > 1) { /* Attempt to move tasks */ double_lock_balance(this_rq, busiest); /* this_rq->clock is already updated */ update_rq_clock(busiest); ld_moved = move_tasks(this_rq, this_cpu, busiest, imbalance, sd, CPU_NEWLY_IDLE, &all_pinned); spin_unlock(&busiest->lock); if (unlikely(all_pinned)) { cpu_clear(cpu_of(busiest), cpus); if (!cpus_empty(cpus)) goto redo; } } if (!ld_moved) { schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]); if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER && !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) return -1; } else sd->nr_balance_failed = 0; return ld_moved; out_balanced: schedstat_inc(sd, lb_balanced[CPU_NEWLY_IDLE]); if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER && !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) return -1; sd->nr_balance_failed = 0; return 0; } /* * idle_balance is called by schedule() if this_cpu is about to become * idle. Attempts to pull tasks from other CPUs. */ static void idle_balance(int this_cpu, struct rq *this_rq) { struct sched_domain *sd; int pulled_task = -1; unsigned long next_balance = jiffies + HZ; for_each_domain(this_cpu, sd) { unsigned long interval; if (!(sd->flags & SD_LOAD_BALANCE)) continue; if (sd->flags & SD_BALANCE_NEWIDLE) /* If we've pulled tasks over stop searching: */ pulled_task = load_balance_newidle(this_cpu, this_rq, sd); interval = msecs_to_jiffies(sd->balance_interval); if (time_after(next_balance, sd->last_balance + interval)) next_balance = sd->last_balance + interval; if (pulled_task) break; } if (pulled_task || time_after(jiffies, this_rq->next_balance)) { /* * We are going idle. next_balance may be set based on * a busy processor. So reset next_balance. */ this_rq->next_balance = next_balance; } } /* * active_load_balance is run by migration threads. It pushes running tasks * off the busiest CPU onto idle CPUs. It requires at least 1 task to be * running on each physical CPU where possible, and avoids physical / * logical imbalances. * * Called with busiest_rq locked. */ static void active_load_balance(struct rq *busiest_rq, int busiest_cpu) { int target_cpu = busiest_rq->push_cpu; struct sched_domain *sd; struct rq *target_rq; /* Is there any task to move? */ if (busiest_rq->nr_running <= 1) return; target_rq = cpu_rq(target_cpu); /* * This condition is "impossible", if it occurs * we need to fix it. Originally reported by * Bjorn Helgaas on a 128-cpu setup. */ BUG_ON(busiest_rq == target_rq); /* move a task from busiest_rq to target_rq */ double_lock_balance(busiest_rq, target_rq); update_rq_clock(busiest_rq); update_rq_clock(target_rq); /* Search for an sd spanning us and the target CPU. */ for_each_domain(target_cpu, sd) { if ((sd->flags & SD_LOAD_BALANCE) && cpu_isset(busiest_cpu, sd->span)) break; } if (likely(sd)) { schedstat_inc(sd, alb_count); if (move_one_task(target_rq, target_cpu, busiest_rq, sd, CPU_IDLE)) schedstat_inc(sd, alb_pushed); else schedstat_inc(sd, alb_failed); } spin_unlock(&target_rq->lock); } #ifdef CONFIG_NO_HZ static struct { atomic_t load_balancer; cpumask_t cpu_mask; } nohz ____cacheline_aligned = { .load_balancer = ATOMIC_INIT(-1), .cpu_mask = CPU_MASK_NONE, }; /* * This routine will try to nominate the ilb (idle load balancing) * owner among the cpus whose ticks are stopped. ilb owner will do the idle * load balancing on behalf of all those cpus. If all the cpus in the system * go into this tickless mode, then there will be no ilb owner (as there is * no need for one) and all the cpus will sleep till the next wakeup event * arrives... * * For the ilb owner, tick is not stopped. And this tick will be used * for idle load balancing. ilb owner will still be part of * nohz.cpu_mask.. * * While stopping the tick, this cpu will become the ilb owner if there * is no other owner. And will be the owner till that cpu becomes busy * or if all cpus in the system stop their ticks at which point * there is no need for ilb owner. * * When the ilb owner becomes busy, it nominates another owner, during the * next busy scheduler_tick() */ int select_nohz_load_balancer(int stop_tick) { int cpu = smp_processor_id(); if (stop_tick) { cpu_set(cpu, nohz.cpu_mask); cpu_rq(cpu)->in_nohz_recently = 1; /* * If we are going offline and still the leader, give up! */ if (cpu_is_offline(cpu) && atomic_read(&nohz.load_balancer) == cpu) { if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu) BUG(); return 0; } /* time for ilb owner also to sleep */ if (cpus_weight(nohz.cpu_mask) == num_online_cpus()) { if (atomic_read(&nohz.load_balancer) == cpu) atomic_set(&nohz.load_balancer, -1); return 0; } if (atomic_read(&nohz.load_balancer) == -1) { /* make me the ilb owner */ if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1) return 1; } else if (atomic_read(&nohz.load_balancer) == cpu) return 1; } else { if (!cpu_isset(cpu, nohz.cpu_mask)) return 0; cpu_clear(cpu, nohz.cpu_mask); if (atomic_read(&nohz.load_balancer) == cpu) if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu) BUG(); } return 0; } #endif static DEFINE_SPINLOCK(balancing); /* * It checks each scheduling domain to see if it is due to be balanced, * and initiates a balancing operation if so. * * Balancing parameters are set up in arch_init_sched_domains. */ static void rebalance_domains(int cpu, enum cpu_idle_type idle) { int balance = 1; struct rq *rq = cpu_rq(cpu); unsigned long interval; struct sched_domain *sd; /* Earliest time when we have to do rebalance again */ unsigned long next_balance = jiffies + 60*HZ; int update_next_balance = 0; for_each_domain(cpu, sd) { if (!(sd->flags & SD_LOAD_BALANCE)) continue; interval = sd->balance_interval; if (idle != CPU_IDLE) interval *= sd->busy_factor; /* scale ms to jiffies */ interval = msecs_to_jiffies(interval); if (unlikely(!interval)) interval = 1; if (interval > HZ*NR_CPUS/10) interval = HZ*NR_CPUS/10; if (sd->flags & SD_SERIALIZE) { if (!spin_trylock(&balancing)) goto out; } if (time_after_eq(jiffies, sd->last_balance + interval)) { if (load_balance(cpu, rq, sd, idle, &balance)) { /* * We've pulled tasks over so either we're no * longer idle, or one of our SMT siblings is * not idle. */ idle = CPU_NOT_IDLE; } sd->last_balance = jiffies; } if (sd->flags & SD_SERIALIZE) spin_unlock(&balancing); out: if (time_after(next_balance, sd->last_balance + interval)) { next_balance = sd->last_balance + interval; update_next_balance = 1; } /* * Stop the load balance at this level. There is another * CPU in our sched group which is doing load balancing more * actively. */ if (!balance) break; } /* * next_balance will be updated only when there is a need. * When the cpu is attached to null domain for ex, it will not be * updated. */ if (likely(update_next_balance)) rq->next_balance = next_balance; } /* * run_rebalance_domains is triggered when needed from the scheduler tick. * In CONFIG_NO_HZ case, the idle load balance owner will do the * rebalancing for all the cpus for whom scheduler ticks are stopped. */ static void run_rebalance_domains(struct softirq_action *h) { int this_cpu = smp_processor_id(); struct rq *this_rq = cpu_rq(this_cpu); enum cpu_idle_type idle = this_rq->idle_at_tick ? CPU_IDLE : CPU_NOT_IDLE; rebalance_domains(this_cpu, idle); #ifdef CONFIG_NO_HZ /* * If this cpu is the owner for idle load balancing, then do the * balancing on behalf of the other idle cpus whose ticks are * stopped. */ if (this_rq->idle_at_tick && atomic_read(&nohz.load_balancer) == this_cpu) { cpumask_t cpus = nohz.cpu_mask; struct rq *rq; int balance_cpu; cpu_clear(this_cpu, cpus); for_each_cpu_mask(balance_cpu, cpus) { /* * If this cpu gets work to do, stop the load balancing * work being done for other cpus. Next load * balancing owner will pick it up. */ if (need_resched()) break; rebalance_domains(balance_cpu, CPU_IDLE); rq = cpu_rq(balance_cpu); if (time_after(this_rq->next_balance, rq->next_balance)) this_rq->next_balance = rq->next_balance; } } #endif } /* * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing. * * In case of CONFIG_NO_HZ, this is the place where we nominate a new * idle load balancing owner or decide to stop the periodic load balancing, * if the whole system is idle. */ static inline void trigger_load_balance(struct rq *rq, int cpu) { #ifdef CONFIG_NO_HZ /* * If we were in the nohz mode recently and busy at the current * scheduler tick, then check if we need to nominate new idle * load balancer. */ if (rq->in_nohz_recently && !rq->idle_at_tick) { rq->in_nohz_recently = 0; if (atomic_read(&nohz.load_balancer) == cpu) { cpu_clear(cpu, nohz.cpu_mask); atomic_set(&nohz.load_balancer, -1); } if (atomic_read(&nohz.load_balancer) == -1) { /* * simple selection for now: Nominate the * first cpu in the nohz list to be the next * ilb owner. * * TBD: Traverse the sched domains and nominate * the nearest cpu in the nohz.cpu_mask. */ int ilb = first_cpu(nohz.cpu_mask); if (ilb != NR_CPUS) resched_cpu(ilb); } } /* * If this cpu is idle and doing idle load balancing for all the * cpus with ticks stopped, is it time for that to stop? */ if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu && cpus_weight(nohz.cpu_mask) == num_online_cpus()) { resched_cpu(cpu); return; } /* * If this cpu is idle and the idle load balancing is done by * someone else, then no need raise the SCHED_SOFTIRQ */ if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu && cpu_isset(cpu, nohz.cpu_mask)) return; #endif if (time_after_eq(jiffies, rq->next_balance)) raise_softirq(SCHED_SOFTIRQ); } #else /* CONFIG_SMP */ /* * on UP we do not need to balance between CPUs: */ static inline void idle_balance(int cpu, struct rq *rq) { } #endif DEFINE_PER_CPU(struct kernel_stat, kstat); EXPORT_PER_CPU_SYMBOL(kstat); /* * Return p->sum_exec_runtime plus any more ns on the sched_clock * that have not yet been banked in case the task is currently running. */ unsigned long long task_sched_runtime(struct task_struct *p) { unsigned long flags; u64 ns, delta_exec; struct rq *rq; rq = task_rq_lock(p, &flags); ns = p->se.sum_exec_runtime; if (rq->curr == p) { update_rq_clock(rq); delta_exec = rq->clock - p->se.exec_start; if ((s64)delta_exec > 0) ns += delta_exec; } task_rq_unlock(rq, &flags); return ns; } /* * Account user cpu time to a process. * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in user space since the last update */ void account_user_time(struct task_struct *p, cputime_t cputime) { struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t tmp; p->utime = cputime_add(p->utime, cputime); /* Add user time to cpustat. */ tmp = cputime_to_cputime64(cputime); if (TASK_NICE(p) > 0) cpustat->nice = cputime64_add(cpustat->nice, tmp); else cpustat->user = cputime64_add(cpustat->user, tmp); } /* * Account guest cpu time to a process. * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in virtual machine since the last update */ static void account_guest_time(struct task_struct *p, cputime_t cputime) { cputime64_t tmp; struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; tmp = cputime_to_cputime64(cputime); p->utime = cputime_add(p->utime, cputime); p->gtime = cputime_add(p->gtime, cputime); cpustat->user = cputime64_add(cpustat->user, tmp); cpustat->guest = cputime64_add(cpustat->guest, tmp); } /* * Account scaled user cpu time to a process. * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in user space since the last update */ void account_user_time_scaled(struct task_struct *p, cputime_t cputime) { p->utimescaled = cputime_add(p->utimescaled, cputime); } /* * Account system cpu time to a process. * @p: the process that the cpu time gets accounted to * @hardirq_offset: the offset to subtract from hardirq_count() * @cputime: the cpu time spent in kernel space since the last update */ void account_system_time(struct task_struct *p, int hardirq_offset, cputime_t cputime) { struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; struct rq *rq = this_rq(); cputime64_t tmp; if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) return account_guest_time(p, cputime); p->stime = cputime_add(p->stime, cputime); /* Add system time to cpustat. */ tmp = cputime_to_cputime64(cputime); if (hardirq_count() - hardirq_offset) cpustat->irq = cputime64_add(cpustat->irq, tmp); else if (softirq_count()) cpustat->softirq = cputime64_add(cpustat->softirq, tmp); else if (p != rq->idle) cpustat->system = cputime64_add(cpustat->system, tmp); else if (atomic_read(&rq->nr_iowait) > 0) cpustat->iowait = cputime64_add(cpustat->iowait, tmp); else cpustat->idle = cputime64_add(cpustat->idle, tmp); /* Account for system time used */ acct_update_integrals(p); } /* * Account scaled system cpu time to a process. * @p: the process that the cpu time gets accounted to * @hardirq_offset: the offset to subtract from hardirq_count() * @cputime: the cpu time spent in kernel space since the last update */ void account_system_time_scaled(struct task_struct *p, cputime_t cputime) { p->stimescaled = cputime_add(p->stimescaled, cputime); } /* * Account for involuntary wait time. * @p: the process from which the cpu time has been stolen * @steal: the cpu time spent in involuntary wait */ void account_steal_time(struct task_struct *p, cputime_t steal) { struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t tmp = cputime_to_cputime64(steal); struct rq *rq = this_rq(); if (p == rq->idle) { p->stime = cputime_add(p->stime, steal); if (atomic_read(&rq->nr_iowait) > 0) cpustat->iowait = cputime64_add(cpustat->iowait, tmp); else cpustat->idle = cputime64_add(cpustat->idle, tmp); } else cpustat->steal = cputime64_add(cpustat->steal, tmp); } /* * This function gets called by the timer code, with HZ frequency. * We call it with interrupts disabled. * * It also gets called by the fork code, when changing the parent's * timeslices. */ void scheduler_tick(void) { int cpu = smp_processor_id(); struct rq *rq = cpu_rq(cpu); struct task_struct *curr = rq->curr; u64 next_tick = rq->tick_timestamp + TICK_NSEC; spin_lock(&rq->lock); __update_rq_clock(rq); /* * Let rq->clock advance by at least TICK_NSEC: */ if (unlikely(rq->clock < next_tick)) rq->clock = next_tick; rq->tick_timestamp = rq->clock; update_cpu_load(rq); if (curr != rq->idle) /* FIXME: needed? */ curr->sched_class->task_tick(rq, curr); spin_unlock(&rq->lock); #ifdef CONFIG_SMP rq->idle_at_tick = idle_cpu(cpu); trigger_load_balance(rq, cpu); #endif } #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT) void fastcall add_preempt_count(int val) { /* * Underflow? */ if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) return; preempt_count() += val; /* * Spinlock count overflowing soon? */ DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK - 10); } EXPORT_SYMBOL(add_preempt_count); void fastcall sub_preempt_count(int val) { /* * Underflow? */ if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) return; /* * Is the spinlock portion underflowing? */ if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && !(preempt_count() & PREEMPT_MASK))) return; preempt_count() -= val; } EXPORT_SYMBOL(sub_preempt_count); #endif /* * Print scheduling while atomic bug: */ static noinline void __schedule_bug(struct task_struct *prev) { struct pt_regs *regs = get_irq_regs(); printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", prev->comm, prev->pid, preempt_count()); debug_show_held_locks(prev); if (irqs_disabled()) print_irqtrace_events(prev); if (regs) show_regs(regs); else dump_stack(); } /* * Various schedule()-time debugging checks and statistics: */ static inline void schedule_debug(struct task_struct *prev) { /* * Test if we are atomic. Since do_exit() needs to call into * schedule() atomically, we ignore that path for now. * Otherwise, whine if we are scheduling when we should not be. */ if (unlikely(in_atomic_preempt_off()) && unlikely(!prev->exit_state)) __schedule_bug(prev); profile_hit(SCHED_PROFILING, __builtin_return_address(0)); schedstat_inc(this_rq(), sched_count); #ifdef CONFIG_SCHEDSTATS if (unlikely(prev->lock_depth >= 0)) { schedstat_inc(this_rq(), bkl_count); schedstat_inc(prev, sched_info.bkl_count); } #endif } /* * Pick up the highest-prio task: */ static inline struct task_struct * pick_next_task(struct rq *rq, struct task_struct *prev) { const struct sched_class *class; struct task_struct *p; /* * Optimization: we know that if all tasks are in * the fair class we can call that function directly: */ if (likely(rq->nr_running == rq->cfs.nr_running)) { p = fair_sched_class.pick_next_task(rq); if (likely(p)) return p; } class = sched_class_highest; for ( ; ; ) { p = class->pick_next_task(rq); if (p) return p; /* * Will never be NULL as the idle class always * returns a non-NULL p: */ class = class->next; } } /* * schedule() is the main scheduler function. */ asmlinkage void __sched schedule(void) { struct task_struct *prev, *next; long *switch_count; struct rq *rq; int cpu; need_resched: preempt_disable(); cpu = smp_processor_id(); rq = cpu_rq(cpu); rcu_qsctr_inc(cpu); prev = rq->curr; switch_count = &prev->nivcsw; release_kernel_lock(prev); need_resched_nonpreemptible: schedule_debug(prev); /* * Do the rq-clock update outside the rq lock: */ local_irq_disable(); __update_rq_clock(rq); spin_lock(&rq->lock); clear_tsk_need_resched(prev); if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { if (unlikely((prev->state & TASK_INTERRUPTIBLE) && unlikely(signal_pending(prev)))) { prev->state = TASK_RUNNING; } else { deactivate_task(rq, prev, 1); } switch_count = &prev->nvcsw; } if (unlikely(!rq->nr_running)) idle_balance(cpu, rq); prev->sched_class->put_prev_task(rq, prev); next = pick_next_task(rq, prev); sched_info_switch(prev, next); if (likely(prev != next)) { rq->nr_switches++; rq->curr = next; ++*switch_count; context_switch(rq, prev, next); /* unlocks the rq */ } else spin_unlock_irq(&rq->lock); if (unlikely(reacquire_kernel_lock(current) < 0)) { cpu = smp_processor_id(); rq = cpu_rq(cpu); goto need_resched_nonpreemptible; } preempt_enable_no_resched(); if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) goto need_resched; } EXPORT_SYMBOL(schedule); #ifdef CONFIG_PREEMPT /* * this is the entry point to schedule() from in-kernel preemption * off of preempt_enable. Kernel preemptions off return from interrupt * occur there and call schedule directly. */ asmlinkage void __sched preempt_schedule(void) { struct thread_info *ti = current_thread_info(); #ifdef CONFIG_PREEMPT_BKL struct task_struct *task = current; int saved_lock_depth; #endif /* * If there is a non-zero preempt_count or interrupts are disabled, * we do not want to preempt the current task. Just return.. */ if (likely(ti->preempt_count || irqs_disabled())) return; do { add_preempt_count(PREEMPT_ACTIVE); /* * We keep the big kernel semaphore locked, but we * clear ->lock_depth so that schedule() doesnt * auto-release the semaphore: */ #ifdef CONFIG_PREEMPT_BKL saved_lock_depth = task->lock_depth; task->lock_depth = -1; #endif schedule(); #ifdef CONFIG_PREEMPT_BKL task->lock_depth = saved_lock_depth; #endif sub_preempt_count(PREEMPT_ACTIVE); /* * Check again in case we missed a preemption opportunity * between schedule and now. */ barrier(); } while (unlikely(test_thread_flag(TIF_NEED_RESCHED))); } EXPORT_SYMBOL(preempt_schedule); /* * this is the entry point to schedule() from kernel preemption * off of irq context. * Note, that this is called and return with irqs disabled. This will * protect us against recursive calling from irq. */ asmlinkage void __sched preempt_schedule_irq(void) { struct thread_info *ti = current_thread_info(); #ifdef CONFIG_PREEMPT_BKL struct task_struct *task = current; int saved_lock_depth; #endif /* Catch callers which need to be fixed */ BUG_ON(ti->preempt_count || !irqs_disabled()); do { add_preempt_count(PREEMPT_ACTIVE); /* * We keep the big kernel semaphore locked, but we * clear ->lock_depth so that schedule() doesnt * auto-release the semaphore: */ #ifdef CONFIG_PREEMPT_BKL saved_lock_depth = task->lock_depth; task->lock_depth = -1; #endif local_irq_enable(); schedule(); local_irq_disable(); #ifdef CONFIG_PREEMPT_BKL task->lock_depth = saved_lock_depth; #endif sub_preempt_count(PREEMPT_ACTIVE); /* * Check again in case we missed a preemption opportunity * between schedule and now. */ barrier(); } while (unlikely(test_thread_flag(TIF_NEED_RESCHED))); } #endif /* CONFIG_PREEMPT */ int default_wake_function(wait_queue_t *curr, unsigned mode, int sync, void *key) { return try_to_wake_up(curr->private, mode, sync); } EXPORT_SYMBOL(default_wake_function); /* * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve * number) then we wake all the non-exclusive tasks and one exclusive task. * * There are circumstances in which we can try to wake a task which has already * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns * zero in this (rare) case, and we handle it by continuing to scan the queue. */ static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, int nr_exclusive, int sync, void *key) { wait_queue_t *curr, *next; list_for_each_entry_safe(curr, next, &q->task_list, task_list) { unsigned flags = curr->flags; if (curr->func(curr, mode, sync, key) && (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) break; } } /** * __wake_up - wake up threads blocked on a waitqueue. * @q: the waitqueue * @mode: which threads * @nr_exclusive: how many wake-one or wake-many threads to wake up * @key: is directly passed to the wakeup function */ void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode, int nr_exclusive, void *key) { unsigned long flags; spin_lock_irqsave(&q->lock, flags); __wake_up_common(q, mode, nr_exclusive, 0, key); spin_unlock_irqrestore(&q->lock, flags); } EXPORT_SYMBOL(__wake_up); /* * Same as __wake_up but called with the spinlock in wait_queue_head_t held. */ void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode) { __wake_up_common(q, mode, 1, 0, NULL); } /** * __wake_up_sync - wake up threads blocked on a waitqueue. * @q: the waitqueue * @mode: which threads * @nr_exclusive: how many wake-one or wake-many threads to wake up * * The sync wakeup differs that the waker knows that it will schedule * away soon, so while the target thread will be woken up, it will not * be migrated to another CPU - ie. the two threads are 'synchronized' * with each other. This can prevent needless bouncing between CPUs. * * On UP it can prevent extra preemption. */ void fastcall __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive) { unsigned long flags; int sync = 1; if (unlikely(!q)) return; if (unlikely(!nr_exclusive)) sync = 0; spin_lock_irqsave(&q->lock, flags); __wake_up_common(q, mode, nr_exclusive, sync, NULL); spin_unlock_irqrestore(&q->lock, flags); } EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */ void complete(struct completion *x) { unsigned long flags; spin_lock_irqsave(&x->wait.lock, flags); x->done++; __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 1, 0, NULL); spin_unlock_irqrestore(&x->wait.lock, flags); } EXPORT_SYMBOL(complete); void complete_all(struct completion *x) { unsigned long flags; spin_lock_irqsave(&x->wait.lock, flags); x->done += UINT_MAX/2; __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 0, 0, NULL); spin_unlock_irqrestore(&x->wait.lock, flags); } EXPORT_SYMBOL(complete_all); static inline long __sched do_wait_for_common(struct completion *x, long timeout, int state) { if (!x->done) { DECLARE_WAITQUEUE(wait, current); wait.flags |= WQ_FLAG_EXCLUSIVE; __add_wait_queue_tail(&x->wait, &wait); do { if (state == TASK_INTERRUPTIBLE && signal_pending(current)) { __remove_wait_queue(&x->wait, &wait); return -ERESTARTSYS; } __set_current_state(state); spin_unlock_irq(&x->wait.lock); timeout = schedule_timeout(timeout); spin_lock_irq(&x->wait.lock); if (!timeout) { __remove_wait_queue(&x->wait, &wait); return timeout; } } while (!x->done); __remove_wait_queue(&x->wait, &wait); } x->done--; return timeout; } static long __sched wait_for_common(struct completion *x, long timeout, int state) { might_sleep(); spin_lock_irq(&x->wait.lock); timeout = do_wait_for_common(x, timeout, state); spin_unlock_irq(&x->wait.lock); return timeout; } void __sched wait_for_completion(struct completion *x) { wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); } EXPORT_SYMBOL(wait_for_completion); unsigned long __sched wait_for_completion_timeout(struct completion *x, unsigned long timeout) { return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE); } EXPORT_SYMBOL(wait_for_completion_timeout); int __sched wait_for_completion_interruptible(struct completion *x) { long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE); if (t == -ERESTARTSYS) return t; return 0; } EXPORT_SYMBOL(wait_for_completion_interruptible); unsigned long __sched wait_for_completion_interruptible_timeout(struct completion *x, unsigned long timeout) { return wait_for_common(x, timeout, TASK_INTERRUPTIBLE); } EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); static long __sched sleep_on_common(wait_queue_head_t *q, int state, long timeout) { unsigned long flags; wait_queue_t wait; init_waitqueue_entry(&wait, current); __set_current_state(state); spin_lock_irqsave(&q->lock, flags); __add_wait_queue(q, &wait); spin_unlock(&q->lock); timeout = schedule_timeout(timeout); spin_lock_irq(&q->lock); __remove_wait_queue(q, &wait); spin_unlock_irqrestore(&q->lock, flags); return timeout; } void __sched interruptible_sleep_on(wait_queue_head_t *q) { sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); } EXPORT_SYMBOL(interruptible_sleep_on); long __sched interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout) { return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout); } EXPORT_SYMBOL(interruptible_sleep_on_timeout); void __sched sleep_on(wait_queue_head_t *q) { sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); } EXPORT_SYMBOL(sleep_on); long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout) { return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout); } EXPORT_SYMBOL(sleep_on_timeout); #ifdef CONFIG_RT_MUTEXES /* * rt_mutex_setprio - set the current priority of a task * @p: task * @prio: prio value (kernel-internal form) * * This function changes the 'effective' priority of a task. It does * not touch ->normal_prio like __setscheduler(). * * Used by the rt_mutex code to implement priority inheritance logic. */ void rt_mutex_setprio(struct task_struct *p, int prio) { unsigned long flags; int oldprio, on_rq, running; struct rq *rq; BUG_ON(prio < 0 || prio > MAX_PRIO); rq = task_rq_lock(p, &flags); update_rq_clock(rq); oldprio = p->prio; on_rq = p->se.on_rq; running = task_running(rq, p); if (on_rq) { dequeue_task(rq, p, 0); if (running) p->sched_class->put_prev_task(rq, p); } if (rt_prio(prio)) p->sched_class = &rt_sched_class; else p->sched_class = &fair_sched_class; p->prio = prio; if (on_rq) { if (running) p->sched_class->set_curr_task(rq); enqueue_task(rq, p, 0); /* * Reschedule if we are currently running on this runqueue and * our priority decreased, or if we are not currently running on * this runqueue and our priority is higher than the current's */ if (running) { if (p->prio > oldprio) resched_task(rq->curr); } else { check_preempt_curr(rq, p); } } task_rq_unlock(rq, &flags); } #endif void set_user_nice(struct task_struct *p, long nice) { int old_prio, delta, on_rq; unsigned long flags; struct rq *rq; if (TASK_NICE(p) == nice || nice < -20 || nice > 19) return; /* * We have to be careful, if called from sys_setpriority(), * the task might be in the middle of scheduling on another CPU. */ rq = task_rq_lock(p, &flags); update_rq_clock(rq); /* * The RT priorities are set via sched_setscheduler(), but we still * allow the 'normal' nice value to be set - but as expected * it wont have any effect on scheduling until the task is * SCHED_FIFO/SCHED_RR: */ if (task_has_rt_policy(p)) { p->static_prio = NICE_TO_PRIO(nice); goto out_unlock; } on_rq = p->se.on_rq; if (on_rq) { dequeue_task(rq, p, 0); dec_load(rq, p); } p->static_prio = NICE_TO_PRIO(nice); set_load_weight(p); old_prio = p->prio; p->prio = effective_prio(p); delta = p->prio - old_prio; if (on_rq) { enqueue_task(rq, p, 0); inc_load(rq, p); /* * If the task increased its priority or is running and * lowered its priority, then reschedule its CPU: */ if (delta < 0 || (delta > 0 && task_running(rq, p))) resched_task(rq->curr); } out_unlock: task_rq_unlock(rq, &flags); } EXPORT_SYMBOL(set_user_nice); /* * can_nice - check if a task can reduce its nice value * @p: task * @nice: nice value */ int can_nice(const struct task_struct *p, const int nice) { /* convert nice value [19,-20] to rlimit style value [1,40] */ int nice_rlim = 20 - nice; return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur || capable(CAP_SYS_NICE)); } #ifdef __ARCH_WANT_SYS_NICE /* * sys_nice - change the priority of the current process. * @increment: priority increment * * sys_setpriority is a more generic, but much slower function that * does similar things. */ asmlinkage long sys_nice(int increment) { long nice, retval; /* * Setpriority might change our priority at the same moment. * We don't have to worry. Conceptually one call occurs first * and we have a single winner. */ if (increment < -40) increment = -40; if (increment > 40) increment = 40; nice = PRIO_TO_NICE(current->static_prio) + increment; if (nice < -20) nice = -20; if (nice > 19) nice = 19; if (increment < 0 && !can_nice(current, nice)) return -EPERM; retval = security_task_setnice(current, nice); if (retval) return retval; set_user_nice(current, nice); return 0; } #endif /** * task_prio - return the priority value of a given task. * @p: the task in question. * * This is the priority value as seen by users in /proc. * RT tasks are offset by -200. Normal tasks are centered * around 0, value goes from -16 to +15. */ int task_prio(const struct task_struct *p) { return p->prio - MAX_RT_PRIO; } /** * task_nice - return the nice value of a given task. * @p: the task in question. */ int task_nice(const struct task_struct *p) { return TASK_NICE(p); } EXPORT_SYMBOL_GPL(task_nice); /** * idle_cpu - is a given cpu idle currently? * @cpu: the processor in question. */ int idle_cpu(int cpu) { return cpu_curr(cpu) == cpu_rq(cpu)->idle; } /** * idle_task - return the idle task for a given cpu. * @cpu: the processor in question. */ struct task_struct *idle_task(int cpu) { return cpu_rq(cpu)->idle; } /** * find_process_by_pid - find a process with a matching PID value. * @pid: the pid in question. */ static struct task_struct *find_process_by_pid(pid_t pid) { return pid ? find_task_by_vpid(pid) : current; } /* Actually do priority change: must hold rq lock. */ static void __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio) { BUG_ON(p->se.on_rq); p->policy = policy; switch (p->policy) { case SCHED_NORMAL: case SCHED_BATCH: case SCHED_IDLE: p->sched_class = &fair_sched_class; break; case SCHED_FIFO: case SCHED_RR: p->sched_class = &rt_sched_class; break; } p->rt_priority = prio; p->normal_prio = normal_prio(p); /* we are holding p->pi_lock already */ p->prio = rt_mutex_getprio(p); set_load_weight(p); } /** * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. * @p: the task in question. * @policy: new policy. * @param: structure containing the new RT priority. * * NOTE that the task may be already dead. */ int sched_setscheduler(struct task_struct *p, int policy, struct sched_param *param) { int retval, oldprio, oldpolicy = -1, on_rq, running; unsigned long flags; struct rq *rq; /* may grab non-irq protected spin_locks */ BUG_ON(in_interrupt()); recheck: /* double check policy once rq lock held */ if (policy < 0) policy = oldpolicy = p->policy; else if (policy != SCHED_FIFO && policy != SCHED_RR && policy != SCHED_NORMAL && policy != SCHED_BATCH && policy != SCHED_IDLE) return -EINVAL; /* * Valid priorities for SCHED_FIFO and SCHED_RR are * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, * SCHED_BATCH and SCHED_IDLE is 0. */ if (param->sched_priority < 0 || (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) || (!p->mm && param->sched_priority > MAX_RT_PRIO-1)) return -EINVAL; if (rt_policy(policy) != (param->sched_priority != 0)) return -EINVAL; /* * Allow unprivileged RT tasks to decrease priority: */ if (!capable(CAP_SYS_NICE)) { if (rt_policy(policy)) { unsigned long rlim_rtprio; if (!lock_task_sighand(p, &flags)) return -ESRCH; rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur; unlock_task_sighand(p, &flags); /* can't set/change the rt policy */ if (policy != p->policy && !rlim_rtprio) return -EPERM; /* can't increase priority */ if (param->sched_priority > p->rt_priority && param->sched_priority > rlim_rtprio) return -EPERM; } /* * Like positive nice levels, dont allow tasks to * move out of SCHED_IDLE either: */ if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) return -EPERM; /* can't change other user's priorities */ if ((current->euid != p->euid) && (current->euid != p->uid)) return -EPERM; } retval = security_task_setscheduler(p, policy, param); if (retval) return retval; /* * make sure no PI-waiters arrive (or leave) while we are * changing the priority of the task: */ spin_lock_irqsave(&p->pi_lock, flags); /* * To be able to change p->policy safely, the apropriate * runqueue lock must be held. */ rq = __task_rq_lock(p); /* recheck policy now with rq lock held */ if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { policy = oldpolicy = -1; __task_rq_unlock(rq); spin_unlock_irqrestore(&p->pi_lock, flags); goto recheck; } update_rq_clock(rq); on_rq = p->se.on_rq; running = task_running(rq, p); if (on_rq) { deactivate_task(rq, p, 0); if (running) p->sched_class->put_prev_task(rq, p); } oldprio = p->prio; __setscheduler(rq, p, policy, param->sched_priority); if (on_rq) { if (running) p->sched_class->set_curr_task(rq); activate_task(rq, p, 0); /* * Reschedule if we are currently running on this runqueue and * our priority decreased, or if we are not currently running on * this runqueue and our priority is higher than the current's */ if (running) { if (p->prio > oldprio) resched_task(rq->curr); } else { check_preempt_curr(rq, p); } } __task_rq_unlock(rq); spin_unlock_irqrestore(&p->pi_lock, flags); rt_mutex_adjust_pi(p); return 0; } EXPORT_SYMBOL_GPL(sched_setscheduler); static int do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) { struct sched_param lparam; struct task_struct *p; int retval; if (!param || pid < 0) return -EINVAL; if (copy_from_user(&lparam, param, sizeof(struct sched_param))) return -EFAULT; rcu_read_lock(); retval = -ESRCH; p = find_process_by_pid(pid); if (p != NULL) retval = sched_setscheduler(p, policy, &lparam); rcu_read_unlock(); return retval; } /** * sys_sched_setscheduler - set/change the scheduler policy and RT priority * @pid: the pid in question. * @policy: new policy. * @param: structure containing the new RT priority. */ asmlinkage long sys_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) { /* negative values for policy are not valid */ if (policy < 0) return -EINVAL; return do_sched_setscheduler(pid, policy, param); } /** * sys_sched_setparam - set/change the RT priority of a thread * @pid: the pid in question. * @param: structure containing the new RT priority. */ asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param) { return do_sched_setscheduler(pid, -1, param); } /** * sys_sched_getscheduler - get the policy (scheduling class) of a thread * @pid: the pid in question. */ asmlinkage long sys_sched_getscheduler(pid_t pid) { struct task_struct *p; int retval; if (pid < 0) return -EINVAL; retval = -ESRCH; read_lock(&tasklist_lock); p = find_process_by_pid(pid); if (p) { retval = security_task_getscheduler(p); if (!retval) retval = p->policy; } read_unlock(&tasklist_lock); return retval; } /** * sys_sched_getscheduler - get the RT priority of a thread * @pid: the pid in question. * @param: structure containing the RT priority. */ asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param) { struct sched_param lp; struct task_struct *p; int retval; if (!param || pid < 0) return -EINVAL; read_lock(&tasklist_lock); p = find_process_by_pid(pid); retval = -ESRCH; if (!p) goto out_unlock; retval = security_task_getscheduler(p); if (retval) goto out_unlock; lp.sched_priority = p->rt_priority; read_unlock(&tasklist_lock); /* * This one might sleep, we cannot do it with a spinlock held ... */ retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; return retval; out_unlock: read_unlock(&tasklist_lock); return retval; } long sched_setaffinity(pid_t pid, cpumask_t new_mask) { cpumask_t cpus_allowed; struct task_struct *p; int retval; mutex_lock(&sched_hotcpu_mutex); read_lock(&tasklist_lock); p = find_process_by_pid(pid); if (!p) { read_unlock(&tasklist_lock); mutex_unlock(&sched_hotcpu_mutex); return -ESRCH; } /* * It is not safe to call set_cpus_allowed with the * tasklist_lock held. We will bump the task_struct's * usage count and then drop tasklist_lock. */ get_task_struct(p); read_unlock(&tasklist_lock); retval = -EPERM; if ((current->euid != p->euid) && (current->euid != p->uid) && !capable(CAP_SYS_NICE)) goto out_unlock; retval = security_task_setscheduler(p, 0, NULL); if (retval) goto out_unlock; cpus_allowed = cpuset_cpus_allowed(p); cpus_and(new_mask, new_mask, cpus_allowed); again: retval = set_cpus_allowed(p, new_mask); if (!retval) { cpus_allowed = cpuset_cpus_allowed(p); if (!cpus_subset(new_mask, cpus_allowed)) { /* * We must have raced with a concurrent cpuset * update. Just reset the cpus_allowed to the * cpuset's cpus_allowed */ new_mask = cpus_allowed; goto again; } } out_unlock: put_task_struct(p); mutex_unlock(&sched_hotcpu_mutex); return retval; } static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, cpumask_t *new_mask) { if (len < sizeof(cpumask_t)) { memset(new_mask, 0, sizeof(cpumask_t)); } else if (len > sizeof(cpumask_t)) { len = sizeof(cpumask_t); } return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; } /** * sys_sched_setaffinity - set the cpu affinity of a process * @pid: pid of the process * @len: length in bytes of the bitmask pointed to by user_mask_ptr * @user_mask_ptr: user-space pointer to the new cpu mask */ asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned long __user *user_mask_ptr) { cpumask_t new_mask; int retval; retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask); if (retval) return retval; return sched_setaffinity(pid, new_mask); } /* * Represents all cpu's present in the system * In systems capable of hotplug, this map could dynamically grow * as new cpu's are detected in the system via any platform specific * method, such as ACPI for e.g. */ cpumask_t cpu_present_map __read_mostly; EXPORT_SYMBOL(cpu_present_map); #ifndef CONFIG_SMP cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL; EXPORT_SYMBOL(cpu_online_map); cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL; EXPORT_SYMBOL(cpu_possible_map); #endif long sched_getaffinity(pid_t pid, cpumask_t *mask) { struct task_struct *p; int retval; mutex_lock(&sched_hotcpu_mutex); read_lock(&tasklist_lock); retval = -ESRCH; p = find_process_by_pid(pid); if (!p) goto out_unlock; retval = security_task_getscheduler(p); if (retval) goto out_unlock; cpus_and(*mask, p->cpus_allowed, cpu_online_map); out_unlock: read_unlock(&tasklist_lock); mutex_unlock(&sched_hotcpu_mutex); return retval; } /** * sys_sched_getaffinity - get the cpu affinity of a process * @pid: pid of the process * @len: length in bytes of the bitmask pointed to by user_mask_ptr * @user_mask_ptr: user-space pointer to hold the current cpu mask */ asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len, unsigned long __user *user_mask_ptr) { int ret; cpumask_t mask; if (len < sizeof(cpumask_t)) return -EINVAL; ret = sched_getaffinity(pid, &mask); if (ret < 0) return ret; if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t))) return -EFAULT; return sizeof(cpumask_t); } /** * sys_sched_yield - yield the current processor to other threads. * * This function yields the current CPU to other tasks. If there are no * other threads running on this CPU then this function will return. */ asmlinkage long sys_sched_yield(void) { struct rq *rq = this_rq_lock(); schedstat_inc(rq, yld_count); current->sched_class->yield_task(rq); /* * Since we are going to call schedule() anyway, there's * no need to preempt or enable interrupts: */ __release(rq->lock); spin_release(&rq->lock.dep_map, 1, _THIS_IP_); _raw_spin_unlock(&rq->lock); preempt_enable_no_resched(); schedule(); return 0; } static void __cond_resched(void) { #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP __might_sleep(__FILE__, __LINE__); #endif /* * The BKS might be reacquired before we have dropped * PREEMPT_ACTIVE, which could trigger a second * cond_resched() call. */ do { add_preempt_count(PREEMPT_ACTIVE); schedule(); sub_preempt_count(PREEMPT_ACTIVE); } while (need_resched()); } int __sched cond_resched(void) { if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) && system_state == SYSTEM_RUNNING) { __cond_resched(); return 1; } return 0; } EXPORT_SYMBOL(cond_resched); /* * cond_resched_lock() - if a reschedule is pending, drop the given lock, * call schedule, and on return reacquire the lock. * * This works OK both with and without CONFIG_PREEMPT. We do strange low-level * operations here to prevent schedule() from being called twice (once via * spin_unlock(), once by hand). */ int cond_resched_lock(spinlock_t *lock) { int ret = 0; if (need_lockbreak(lock)) { spin_unlock(lock); cpu_relax(); ret = 1; spin_lock(lock); } if (need_resched() && system_state == SYSTEM_RUNNING) { spin_release(&lock->dep_map, 1, _THIS_IP_); _raw_spin_unlock(lock); preempt_enable_no_resched(); __cond_resched(); ret = 1; spin_lock(lock); } return ret; } EXPORT_SYMBOL(cond_resched_lock); int __sched cond_resched_softirq(void) { BUG_ON(!in_softirq()); if (need_resched() && system_state == SYSTEM_RUNNING) { local_bh_enable(); __cond_resched(); local_bh_disable(); return 1; } return 0; } EXPORT_SYMBOL(cond_resched_softirq); /** * yield - yield the current processor to other threads. * * This is a shortcut for kernel-space yielding - it marks the * thread runnable and calls sys_sched_yield(). */ void __sched yield(void) { set_current_state(TASK_RUNNING); sys_sched_yield(); } EXPORT_SYMBOL(yield); /* * This task is about to go to sleep on IO. Increment rq->nr_iowait so * that process accounting knows that this is a task in IO wait state. * * But don't do that if it is a deliberate, throttling IO wait (this task * has set its backing_dev_info: the queue against which it should throttle) */ void __sched io_schedule(void) { struct rq *rq = &__raw_get_cpu_var(runqueues); delayacct_blkio_start(); atomic_inc(&rq->nr_iowait); schedule(); atomic_dec(&rq->nr_iowait); delayacct_blkio_end(); } EXPORT_SYMBOL(io_schedule); long __sched io_schedule_timeout(long timeout) { struct rq *rq = &__raw_get_cpu_var(runqueues); long ret; delayacct_blkio_start(); atomic_inc(&rq->nr_iowait); ret = schedule_timeout(timeout); atomic_dec(&rq->nr_iowait); delayacct_blkio_end(); return ret; } /** * sys_sched_get_priority_max - return maximum RT priority. * @policy: scheduling class. * * this syscall returns the maximum rt_priority that can be used * by a given scheduling class. */ asmlinkage long sys_sched_get_priority_max(int policy) { int ret = -EINVAL; switch (policy) { case SCHED_FIFO: case SCHED_RR: ret = MAX_USER_RT_PRIO-1; break; case SCHED_NORMAL: case SCHED_BATCH: case SCHED_IDLE: ret = 0; break; } return ret; } /** * sys_sched_get_priority_min - return minimum RT priority. * @policy: scheduling class. * * this syscall returns the minimum rt_priority that can be used * by a given scheduling class. */ asmlinkage long sys_sched_get_priority_min(int policy) { int ret = -EINVAL; switch (policy) { case SCHED_FIFO: case SCHED_RR: ret = 1; break; case SCHED_NORMAL: case SCHED_BATCH: case SCHED_IDLE: ret = 0; } return ret; } /** * sys_sched_rr_get_interval - return the default timeslice of a process. * @pid: pid of the process. * @interval: userspace pointer to the timeslice value. * * this syscall writes the default timeslice value of a given process * into the user-space timespec buffer. A value of '0' means infinity. */ asmlinkage long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval) { struct task_struct *p; unsigned int time_slice; int retval; struct timespec t; if (pid < 0) return -EINVAL; retval = -ESRCH; read_lock(&tasklist_lock); p = find_process_by_pid(pid); if (!p) goto out_unlock; retval = security_task_getscheduler(p); if (retval) goto out_unlock; if (p->policy == SCHED_FIFO) time_slice = 0; else if (p->policy == SCHED_RR) time_slice = DEF_TIMESLICE; else { struct sched_entity *se = &p->se; unsigned long flags; struct rq *rq; rq = task_rq_lock(p, &flags); time_slice = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); task_rq_unlock(rq, &flags); } read_unlock(&tasklist_lock); jiffies_to_timespec(time_slice, &t); retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; return retval; out_unlock: read_unlock(&tasklist_lock); return retval; } static const char stat_nam[] = "RSDTtZX"; static void show_task(struct task_struct *p) { unsigned long free = 0; unsigned state; state = p->state ? __ffs(p->state) + 1 : 0; printk(KERN_INFO "%-13.13s %c", p->comm, state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); #if BITS_PER_LONG == 32 if (state == TASK_RUNNING) printk(KERN_CONT " running "); else printk(KERN_CONT " %08lx ", thread_saved_pc(p)); #else if (state == TASK_RUNNING) printk(KERN_CONT " running task "); else printk(KERN_CONT " %016lx ", thread_saved_pc(p)); #endif #ifdef CONFIG_DEBUG_STACK_USAGE { unsigned long *n = end_of_stack(p); while (!*n) n++; free = (unsigned long)n - (unsigned long)end_of_stack(p); } #endif printk(KERN_CONT "%5lu %5d %6d\n", free, task_pid_nr(p), task_pid_nr(p->parent)); if (state != TASK_RUNNING) show_stack(p, NULL); } void show_state_filter(unsigned long state_filter) { struct task_struct *g, *p; #if BITS_PER_LONG == 32 printk(KERN_INFO " task PC stack pid father\n"); #else printk(KERN_INFO " task PC stack pid father\n"); #endif read_lock(&tasklist_lock); do_each_thread(g, p) { /* * reset the NMI-timeout, listing all files on a slow * console might take alot of time: */ touch_nmi_watchdog(); if (!state_filter || (p->state & state_filter)) show_task(p); } while_each_thread(g, p); touch_all_softlockup_watchdogs(); #ifdef CONFIG_SCHED_DEBUG sysrq_sched_debug_show(); #endif read_unlock(&tasklist_lock); /* * Only show locks if all tasks are dumped: */ if (state_filter == -1) debug_show_all_locks(); } void __cpuinit init_idle_bootup_task(struct task_struct *idle) { idle->sched_class = &idle_sched_class; } /** * init_idle - set up an idle thread for a given CPU * @idle: task in question * @cpu: cpu the idle task belongs to * * NOTE: this function does not set the idle thread's NEED_RESCHED * flag, to make booting more robust. */ void __cpuinit init_idle(struct task_struct *idle, int cpu) { struct rq *rq = cpu_rq(cpu); unsigned long flags; __sched_fork(idle); idle->se.exec_start = sched_clock(); idle->prio = idle->normal_prio = MAX_PRIO; idle->cpus_allowed = cpumask_of_cpu(cpu); __set_task_cpu(idle, cpu); spin_lock_irqsave(&rq->lock, flags); rq->curr = rq->idle = idle; #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) idle->oncpu = 1; #endif spin_unlock_irqrestore(&rq->lock, flags); /* Set the preempt count _outside_ the spinlocks! */ #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL) task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0); #else task_thread_info(idle)->preempt_count = 0; #endif /* * The idle tasks have their own, simple scheduling class: */ idle->sched_class = &idle_sched_class; } /* * In a system that switches off the HZ timer nohz_cpu_mask * indicates which cpus entered this state. This is used * in the rcu update to wait only for active cpus. For system * which do not switch off the HZ timer nohz_cpu_mask should * always be CPU_MASK_NONE. */ cpumask_t nohz_cpu_mask = CPU_MASK_NONE; /* * Increase the granularity value when there are more CPUs, * because with more CPUs the 'effective latency' as visible * to users decreases. But the relationship is not linear, * so pick a second-best guess by going with the log2 of the * number of CPUs. * * This idea comes from the SD scheduler of Con Kolivas: */ static inline void sched_init_granularity(void) { unsigned int factor = 1 + ilog2(num_online_cpus()); const unsigned long limit = 200000000; sysctl_sched_min_granularity *= factor; if (sysctl_sched_min_granularity > limit) sysctl_sched_min_granularity = limit; sysctl_sched_latency *= factor; if (sysctl_sched_latency > limit) sysctl_sched_latency = limit; sysctl_sched_wakeup_granularity *= factor; sysctl_sched_batch_wakeup_granularity *= factor; } #ifdef CONFIG_SMP /* * This is how migration works: * * 1) we queue a struct migration_req structure in the source CPU's * runqueue and wake up that CPU's migration thread. * 2) we down() the locked semaphore => thread blocks. * 3) migration thread wakes up (implicitly it forces the migrated * thread off the CPU) * 4) it gets the migration request and checks whether the migrated * task is still in the wrong runqueue. * 5) if it's in the wrong runqueue then the migration thread removes * it and puts it into the right queue. * 6) migration thread up()s the semaphore. * 7) we wake up and the migration is done. */ /* * Change a given task's CPU affinity. Migrate the thread to a * proper CPU and schedule it away if the CPU it's executing on * is removed from the allowed bitmask. * * NOTE: the caller must have a valid reference to the task, the * task must not exit() & deallocate itself prematurely. The * call is not atomic; no spinlocks may be held. */ int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask) { struct migration_req req; unsigned long flags; struct rq *rq; int ret = 0; rq = task_rq_lock(p, &flags); if (!cpus_intersects(new_mask, cpu_online_map)) { ret = -EINVAL; goto out; } p->cpus_allowed = new_mask; /* Can the task run on the task's current CPU? If so, we're done */ if (cpu_isset(task_cpu(p), new_mask)) goto out; if (migrate_task(p, any_online_cpu(new_mask), &req)) { /* Need help from migration thread: drop lock and wait. */ task_rq_unlock(rq, &flags); wake_up_process(rq->migration_thread); wait_for_completion(&req.done); tlb_migrate_finish(p->mm); return 0; } out: task_rq_unlock(rq, &flags); return ret; } EXPORT_SYMBOL_GPL(set_cpus_allowed); /* * Move (not current) task off this cpu, onto dest cpu. We're doing * this because either it can't run here any more (set_cpus_allowed() * away from this CPU, or CPU going down), or because we're * attempting to rebalance this task on exec (sched_exec). * * So we race with normal scheduler movements, but that's OK, as long * as the task is no longer on this CPU. * * Returns non-zero if task was successfully migrated. */ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) { struct rq *rq_dest, *rq_src; int ret = 0, on_rq; if (unlikely(cpu_is_offline(dest_cpu))) return ret; rq_src = cpu_rq(src_cpu); rq_dest = cpu_rq(dest_cpu); double_rq_lock(rq_src, rq_dest); /* Already moved. */ if (task_cpu(p) != src_cpu) goto out; /* Affinity changed (again). */ if (!cpu_isset(dest_cpu, p->cpus_allowed)) goto out; on_rq = p->se.on_rq; if (on_rq) deactivate_task(rq_src, p, 0); set_task_cpu(p, dest_cpu); if (on_rq) { activate_task(rq_dest, p, 0); check_preempt_curr(rq_dest, p); } ret = 1; out: double_rq_unlock(rq_src, rq_dest); return ret; } /* * migration_thread - this is a highprio system thread that performs * thread migration by bumping thread off CPU then 'pushing' onto * another runqueue. */ static int migration_thread(void *data) { int cpu = (long)data; struct rq *rq; rq = cpu_rq(cpu); BUG_ON(rq->migration_thread != current); set_current_state(TASK_INTERRUPTIBLE); while (!kthread_should_stop()) { struct migration_req *req; struct list_head *head; spin_lock_irq(&rq->lock); if (cpu_is_offline(cpu)) { spin_unlock_irq(&rq->lock); goto wait_to_die; } if (rq->active_balance) { active_load_balance(rq, cpu); rq->active_balance = 0; } head = &rq->migration_queue; if (list_empty(head)) { spin_unlock_irq(&rq->lock); schedule(); set_current_state(TASK_INTERRUPTIBLE); continue; } req = list_entry(head->next, struct migration_req, list); list_del_init(head->next); spin_unlock(&rq->lock); __migrate_task(req->task, cpu, req->dest_cpu); local_irq_enable(); complete(&req->done); } __set_current_state(TASK_RUNNING); return 0; wait_to_die: /* Wait for kthread_stop */ set_current_state(TASK_INTERRUPTIBLE); while (!kthread_should_stop()) { schedule(); set_current_state(TASK_INTERRUPTIBLE); } __set_current_state(TASK_RUNNING); return 0; } #ifdef CONFIG_HOTPLUG_CPU static int __migrate_task_irq(struct task_struct *p, int src_cpu, int dest_cpu) { int ret; local_irq_disable(); ret = __migrate_task(p, src_cpu, dest_cpu); local_irq_enable(); return ret; } /* * Figure out where task on dead CPU should go, use force if necessary. * NOTE: interrupts should be disabled by the caller */ static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p) { unsigned long flags; cpumask_t mask; struct rq *rq; int dest_cpu; do { /* On same node? */ mask = node_to_cpumask(cpu_to_node(dead_cpu)); cpus_and(mask, mask, p->cpus_allowed); dest_cpu = any_online_cpu(mask); /* On any allowed CPU? */ if (dest_cpu == NR_CPUS) dest_cpu = any_online_cpu(p->cpus_allowed); /* No more Mr. Nice Guy. */ if (dest_cpu == NR_CPUS) { cpumask_t cpus_allowed = cpuset_cpus_allowed_locked(p); /* * Try to stay on the same cpuset, where the * current cpuset may be a subset of all cpus. * The cpuset_cpus_allowed_locked() variant of * cpuset_cpus_allowed() will not block. It must be * called within calls to cpuset_lock/cpuset_unlock. */ rq = task_rq_lock(p, &flags); p->cpus_allowed = cpus_allowed; dest_cpu = any_online_cpu(p->cpus_allowed); task_rq_unlock(rq, &flags); /* * Don't tell them about moving exiting tasks or * kernel threads (both mm NULL), since they never * leave kernel. */ if (p->mm && printk_ratelimit()) printk(KERN_INFO "process %d (%s) no " "longer affine to cpu%d\n", task_pid_nr(p), p->comm, dead_cpu); } } while (!__migrate_task_irq(p, dead_cpu, dest_cpu)); } /* * While a dead CPU has no uninterruptible tasks queued at this point, * it might still have a nonzero ->nr_uninterruptible counter, because * for performance reasons the counter is not stricly tracking tasks to * their home CPUs. So we just add the counter to another CPU's counter, * to keep the global sum constant after CPU-down: */ static void migrate_nr_uninterruptible(struct rq *rq_src) { struct rq *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL)); unsigned long flags; local_irq_save(flags); double_rq_lock(rq_src, rq_dest); rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible; rq_src->nr_uninterruptible = 0; double_rq_unlock(rq_src, rq_dest); local_irq_restore(flags); } /* Run through task list and migrate tasks from the dead cpu. */ static void migrate_live_tasks(int src_cpu) { struct task_struct *p, *t; read_lock(&tasklist_lock); do_each_thread(t, p) { if (p == current) continue; if (task_cpu(p) == src_cpu) move_task_off_dead_cpu(src_cpu, p); } while_each_thread(t, p); read_unlock(&tasklist_lock); } /* * Schedules idle task to be the next runnable task on current CPU. * It does so by boosting its priority to highest possible. * Used by CPU offline code. */ void sched_idle_next(void) { int this_cpu = smp_processor_id(); struct rq *rq = cpu_rq(this_cpu); struct task_struct *p = rq->idle; unsigned long flags; /* cpu has to be offline */ BUG_ON(cpu_online(this_cpu)); /* * Strictly not necessary since rest of the CPUs are stopped by now * and interrupts disabled on the current cpu. */ spin_lock_irqsave(&rq->lock, flags); __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1); update_rq_clock(rq); activate_task(rq, p, 0); spin_unlock_irqrestore(&rq->lock, flags); } /* * Ensures that the idle task is using init_mm right before its cpu goes * offline. */ void idle_task_exit(void) { struct mm_struct *mm = current->active_mm; BUG_ON(cpu_online(smp_processor_id())); if (mm != &init_mm) switch_mm(mm, &init_mm, current); mmdrop(mm); } /* called under rq->lock with disabled interrupts */ static void migrate_dead(unsigned int dead_cpu, struct task_struct *p) { struct rq *rq = cpu_rq(dead_cpu); /* Must be exiting, otherwise would be on tasklist. */ BUG_ON(!p->exit_state); /* Cannot have done final schedule yet: would have vanished. */ BUG_ON(p->state == TASK_DEAD); get_task_struct(p); /* * Drop lock around migration; if someone else moves it, * that's OK. No task can be added to this CPU, so iteration is * fine. */ spin_unlock_irq(&rq->lock); move_task_off_dead_cpu(dead_cpu, p); spin_lock_irq(&rq->lock); put_task_struct(p); } /* release_task() removes task from tasklist, so we won't find dead tasks. */ static void migrate_dead_tasks(unsigned int dead_cpu) { struct rq *rq = cpu_rq(dead_cpu); struct task_struct *next; for ( ; ; ) { if (!rq->nr_running) break; update_rq_clock(rq); next = pick_next_task(rq, rq->curr); if (!next) break; migrate_dead(dead_cpu, next); } } #endif /* CONFIG_HOTPLUG_CPU */ #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) static struct ctl_table sd_ctl_dir[] = { { .procname = "sched_domain", .mode = 0555, }, {0, }, }; static struct ctl_table sd_ctl_root[] = { { .ctl_name = CTL_KERN, .procname = "kernel", .mode = 0555, .child = sd_ctl_dir, }, {0, }, }; static struct ctl_table *sd_alloc_ctl_entry(int n) { struct ctl_table *entry = kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL); return entry; } static void sd_free_ctl_entry(struct ctl_table **tablep) { struct ctl_table *entry; /* * In the intermediate directories, both the child directory and * procname are dynamically allocated and could fail but the mode * will always be set. In the lowest directory the names are * static strings and all have proc handlers. */ for (entry = *tablep; entry->mode; entry++) { if (entry->child) sd_free_ctl_entry(&entry->child); if (entry->proc_handler == NULL) kfree(entry->procname); } kfree(*tablep); *tablep = NULL; } static void set_table_entry(struct ctl_table *entry, const char *procname, void *data, int maxlen, mode_t mode, proc_handler *proc_handler) { entry->procname = procname; entry->data = data; entry->maxlen = maxlen; entry->mode = mode; entry->proc_handler = proc_handler; } static struct ctl_table * sd_alloc_ctl_domain_table(struct sched_domain *sd) { struct ctl_table *table = sd_alloc_ctl_entry(12); if (table == NULL) return NULL; set_table_entry(&table[0], "min_interval", &sd->min_interval, sizeof(long), 0644, proc_doulongvec_minmax); set_table_entry(&table[1], "max_interval", &sd->max_interval, sizeof(long), 0644, proc_doulongvec_minmax); set_table_entry(&table[2], "busy_idx", &sd->busy_idx, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[3], "idle_idx", &sd->idle_idx, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[5], "wake_idx", &sd->wake_idx, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[7], "busy_factor", &sd->busy_factor, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[9], "cache_nice_tries", &sd->cache_nice_tries, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[10], "flags", &sd->flags, sizeof(int), 0644, proc_dointvec_minmax); /* &table[11] is terminator */ return table; } static ctl_table *sd_alloc_ctl_cpu_table(int cpu) { struct ctl_table *entry, *table; struct sched_domain *sd; int domain_num = 0, i; char buf[32]; for_each_domain(cpu, sd) domain_num++; entry = table = sd_alloc_ctl_entry(domain_num + 1); if (table == NULL) return NULL; i = 0; for_each_domain(cpu, sd) { snprintf(buf, 32, "domain%d", i); entry->procname = kstrdup(buf, GFP_KERNEL); entry->mode = 0555; entry->child = sd_alloc_ctl_domain_table(sd); entry++; i++; } return table; } static struct ctl_table_header *sd_sysctl_header; static void register_sched_domain_sysctl(void) { int i, cpu_num = num_online_cpus(); struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1); char buf[32]; WARN_ON(sd_ctl_dir[0].child); sd_ctl_dir[0].child = entry; if (entry == NULL) return; for_each_online_cpu(i) { snprintf(buf, 32, "cpu%d", i); entry->procname = kstrdup(buf, GFP_KERNEL); entry->mode = 0555; entry->child = sd_alloc_ctl_cpu_table(i); entry++; } WARN_ON(sd_sysctl_header); sd_sysctl_header = register_sysctl_table(sd_ctl_root); } /* may be called multiple times per register */ static void unregister_sched_domain_sysctl(void) { if (sd_sysctl_header) unregister_sysctl_table(sd_sysctl_header); sd_sysctl_header = NULL; if (sd_ctl_dir[0].child) sd_free_ctl_entry(&sd_ctl_dir[0].child); } #else static void register_sched_domain_sysctl(void) { } static void unregister_sched_domain_sysctl(void) { } #endif /* * migration_call - callback that gets triggered when a CPU is added. * Here we can start up the necessary migration thread for the new CPU. */ static int __cpuinit migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) { struct task_struct *p; int cpu = (long)hcpu; unsigned long flags; struct rq *rq; switch (action) { case CPU_LOCK_ACQUIRE: mutex_lock(&sched_hotcpu_mutex); break; case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: p = kthread_create(migration_thread, hcpu, "migration/%d", cpu); if (IS_ERR(p)) return NOTIFY_BAD; kthread_bind(p, cpu); /* Must be high prio: stop_machine expects to yield to it. */ rq = task_rq_lock(p, &flags); __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1); task_rq_unlock(rq, &flags); cpu_rq(cpu)->migration_thread = p; break; case CPU_ONLINE: case CPU_ONLINE_FROZEN: /* Strictly unnecessary, as first user will wake it. */ wake_up_process(cpu_rq(cpu)->migration_thread); break; #ifdef CONFIG_HOTPLUG_CPU case CPU_UP_CANCELED: case CPU_UP_CANCELED_FROZEN: if (!cpu_rq(cpu)->migration_thread) break; /* Unbind it from offline cpu so it can run. Fall thru. */ kthread_bind(cpu_rq(cpu)->migration_thread, any_online_cpu(cpu_online_map)); kthread_stop(cpu_rq(cpu)->migration_thread); cpu_rq(cpu)->migration_thread = NULL; break; case CPU_DEAD: case CPU_DEAD_FROZEN: cpuset_lock(); /* around calls to cpuset_cpus_allowed_lock() */ migrate_live_tasks(cpu); rq = cpu_rq(cpu); kthread_stop(rq->migration_thread); rq->migration_thread = NULL; /* Idle task back to normal (off runqueue, low prio) */ spin_lock_irq(&rq->lock); update_rq_clock(rq); deactivate_task(rq, rq->idle, 0); rq->idle->static_prio = MAX_PRIO; __setscheduler(rq, rq->idle, SCHED_NORMAL, 0); rq->idle->sched_class = &idle_sched_class; migrate_dead_tasks(cpu); spin_unlock_irq(&rq->lock); cpuset_unlock(); migrate_nr_uninterruptible(rq); BUG_ON(rq->nr_running != 0); /* No need to migrate the tasks: it was best-effort if * they didn't take sched_hotcpu_mutex. Just wake up * the requestors. */ spin_lock_irq(&rq->lock); while (!list_empty(&rq->migration_queue)) { struct migration_req *req; req = list_entry(rq->migration_queue.next, struct migration_req, list); list_del_init(&req->list); complete(&req->done); } spin_unlock_irq(&rq->lock); break; #endif case CPU_LOCK_RELEASE: mutex_unlock(&sched_hotcpu_mutex); break; } return NOTIFY_OK; } /* Register at highest priority so that task migration (migrate_all_tasks) * happens before everything else. */ static struct notifier_block __cpuinitdata migration_notifier = { .notifier_call = migration_call, .priority = 10 }; void __init migration_init(void) { void *cpu = (void *)(long)smp_processor_id(); int err; /* Start one for the boot CPU: */ err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu); BUG_ON(err == NOTIFY_BAD); migration_call(&migration_notifier, CPU_ONLINE, cpu); register_cpu_notifier(&migration_notifier); } #endif #ifdef CONFIG_SMP /* Number of possible processor ids */ int nr_cpu_ids __read_mostly = NR_CPUS; EXPORT_SYMBOL(nr_cpu_ids); #ifdef CONFIG_SCHED_DEBUG static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level) { struct sched_group *group = sd->groups; cpumask_t groupmask; char str[NR_CPUS]; cpumask_scnprintf(str, NR_CPUS, sd->span); cpus_clear(groupmask); printk(KERN_DEBUG "%*s domain %d: ", level, "", level); if (!(sd->flags & SD_LOAD_BALANCE)) { printk("does not load-balance\n"); if (sd->parent) printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" " has parent"); return -1; } printk(KERN_CONT "span %s\n", str); if (!cpu_isset(cpu, sd->span)) { printk(KERN_ERR "ERROR: domain->span does not contain " "CPU%d\n", cpu); } if (!cpu_isset(cpu, group->cpumask)) { printk(KERN_ERR "ERROR: domain->groups does not contain" " CPU%d\n", cpu); } printk(KERN_DEBUG "%*s groups:", level + 1, ""); do { if (!group) { printk("\n"); printk(KERN_ERR "ERROR: group is NULL\n"); break; } if (!group->__cpu_power) { printk(KERN_CONT "\n"); printk(KERN_ERR "ERROR: domain->cpu_power not " "set\n"); break; } if (!cpus_weight(group->cpumask)) { printk(KERN_CONT "\n"); printk(KERN_ERR "ERROR: empty group\n"); break; } if (cpus_intersects(groupmask, group->cpumask)) { printk(KERN_CONT "\n"); printk(KERN_ERR "ERROR: repeated CPUs\n"); break; } cpus_or(groupmask, groupmask, group->cpumask); cpumask_scnprintf(str, NR_CPUS, group->cpumask); printk(KERN_CONT " %s", str); group = group->next; } while (group != sd->groups); printk(KERN_CONT "\n"); if (!cpus_equal(sd->span, groupmask)) printk(KERN_ERR "ERROR: groups don't span domain->span\n"); if (sd->parent && !cpus_subset(groupmask, sd->parent->span)) printk(KERN_ERR "ERROR: parent span is not a superset " "of domain->span\n"); return 0; } static void sched_domain_debug(struct sched_domain *sd, int cpu) { int level = 0; if (!sd) { printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); return; } printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); for (;;) { if (sched_domain_debug_one(sd, cpu, level)) break; level++; sd = sd->parent; if (!sd) break; } } #else # define sched_domain_debug(sd, cpu) do { } while (0) #endif static int sd_degenerate(struct sched_domain *sd) { if (cpus_weight(sd->span) == 1) return 1; /* Following flags need at least 2 groups */ if (sd->flags & (SD_LOAD_BALANCE | SD_BALANCE_NEWIDLE | SD_BALANCE_FORK | SD_BALANCE_EXEC | SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)) { if (sd->groups != sd->groups->next) return 0; } /* Following flags don't use groups */ if (sd->flags & (SD_WAKE_IDLE | SD_WAKE_AFFINE | SD_WAKE_BALANCE)) return 0; return 1; } static int sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) { unsigned long cflags = sd->flags, pflags = parent->flags; if (sd_degenerate(parent)) return 1; if (!cpus_equal(sd->span, parent->span)) return 0; /* Does parent contain flags not in child? */ /* WAKE_BALANCE is a subset of WAKE_AFFINE */ if (cflags & SD_WAKE_AFFINE) pflags &= ~SD_WAKE_BALANCE; /* Flags needing groups don't count if only 1 group in parent */ if (parent->groups == parent->groups->next) { pflags &= ~(SD_LOAD_BALANCE | SD_BALANCE_NEWIDLE | SD_BALANCE_FORK | SD_BALANCE_EXEC | SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES); } if (~cflags & pflags) return 0; return 1; } /* * Attach the domain 'sd' to 'cpu' as its base domain. Callers must * hold the hotplug lock. */ static void cpu_attach_domain(struct sched_domain *sd, int cpu) { struct rq *rq = cpu_rq(cpu); struct sched_domain *tmp; /* Remove the sched domains which do not contribute to scheduling. */ for (tmp = sd; tmp; tmp = tmp->parent) { struct sched_domain *parent = tmp->parent; if (!parent) break; if (sd_parent_degenerate(tmp, parent)) { tmp->parent = parent->parent; if (parent->parent) parent->parent->child = tmp; } } if (sd && sd_degenerate(sd)) { sd = sd->parent; if (sd) sd->child = NULL; } sched_domain_debug(sd, cpu); rcu_assign_pointer(rq->sd, sd); } /* cpus with isolated domains */ static cpumask_t cpu_isolated_map = CPU_MASK_NONE; /* Setup the mask of cpus configured for isolated domains */ static int __init isolated_cpu_setup(char *str) { int ints[NR_CPUS], i; str = get_options(str, ARRAY_SIZE(ints), ints); cpus_clear(cpu_isolated_map); for (i = 1; i <= ints[0]; i++) if (ints[i] < NR_CPUS) cpu_set(ints[i], cpu_isolated_map); return 1; } __setup("isolcpus=", isolated_cpu_setup); /* * init_sched_build_groups takes the cpumask we wish to span, and a pointer * to a function which identifies what group(along with sched group) a CPU * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS * (due to the fact that we keep track of groups covered with a cpumask_t). * * init_sched_build_groups will build a circular linked list of the groups * covered by the given span, and will set each group's ->cpumask correctly, * and ->cpu_power to 0. */ static void init_sched_build_groups(cpumask_t span, const cpumask_t *cpu_map, int (*group_fn)(int cpu, const cpumask_t *cpu_map, struct sched_group **sg)) { struct sched_group *first = NULL, *last = NULL; cpumask_t covered = CPU_MASK_NONE; int i; for_each_cpu_mask(i, span) { struct sched_group *sg; int group = group_fn(i, cpu_map, &sg); int j; if (cpu_isset(i, covered)) continue; sg->cpumask = CPU_MASK_NONE; sg->__cpu_power = 0; for_each_cpu_mask(j, span) { if (group_fn(j, cpu_map, NULL) != group) continue; cpu_set(j, covered); cpu_set(j, sg->cpumask); } if (!first) first = sg; if (last) last->next = sg; last = sg; } last->next = first; } #define SD_NODES_PER_DOMAIN 16 #ifdef CONFIG_NUMA /** * find_next_best_node - find the next node to include in a sched_domain * @node: node whose sched_domain we're building * @used_nodes: nodes already in the sched_domain * * Find the next node to include in a given scheduling domain. Simply * finds the closest node not already in the @used_nodes map. * * Should use nodemask_t. */ static int find_next_best_node(int node, unsigned long *used_nodes) { int i, n, val, min_val, best_node = 0; min_val = INT_MAX; for (i = 0; i < MAX_NUMNODES; i++) { /* Start at @node */ n = (node + i) % MAX_NUMNODES; if (!nr_cpus_node(n)) continue; /* Skip already used nodes */ if (test_bit(n, used_nodes)) continue; /* Simple min distance search */ val = node_distance(node, n); if (val < min_val) { min_val = val; best_node = n; } } set_bit(best_node, used_nodes); return best_node; } /** * sched_domain_node_span - get a cpumask for a node's sched_domain * @node: node whose cpumask we're constructing * @size: number of nodes to include in this span * * Given a node, construct a good cpumask for its sched_domain to span. It * should be one that prevents unnecessary balancing, but also spreads tasks * out optimally. */ static cpumask_t sched_domain_node_span(int node) { DECLARE_BITMAP(used_nodes, MAX_NUMNODES); cpumask_t span, nodemask; int i; cpus_clear(span); bitmap_zero(used_nodes, MAX_NUMNODES); nodemask = node_to_cpumask(node); cpus_or(span, span, nodemask); set_bit(node, used_nodes); for (i = 1; i < SD_NODES_PER_DOMAIN; i++) { int next_node = find_next_best_node(node, used_nodes); nodemask = node_to_cpumask(next_node); cpus_or(span, span, nodemask); } return span; } #endif int sched_smt_power_savings = 0, sched_mc_power_savings = 0; /* * SMT sched-domains: */ #ifdef CONFIG_SCHED_SMT static DEFINE_PER_CPU(struct sched_domain, cpu_domains); static DEFINE_PER_CPU(struct sched_group, sched_group_cpus); static int cpu_to_cpu_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg) { if (sg) *sg = &per_cpu(sched_group_cpus, cpu); return cpu; } #endif /* * multi-core sched-domains: */ #ifdef CONFIG_SCHED_MC static DEFINE_PER_CPU(struct sched_domain, core_domains); static DEFINE_PER_CPU(struct sched_group, sched_group_core); #endif #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT) static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg) { int group; cpumask_t mask = per_cpu(cpu_sibling_map, cpu); cpus_and(mask, mask, *cpu_map); group = first_cpu(mask); if (sg) *sg = &per_cpu(sched_group_core, group); return group; } #elif defined(CONFIG_SCHED_MC) static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg) { if (sg) *sg = &per_cpu(sched_group_core, cpu); return cpu; } #endif static DEFINE_PER_CPU(struct sched_domain, phys_domains); static DEFINE_PER_CPU(struct sched_group, sched_group_phys); static int cpu_to_phys_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg) { int group; #ifdef CONFIG_SCHED_MC cpumask_t mask = cpu_coregroup_map(cpu); cpus_and(mask, mask, *cpu_map); group = first_cpu(mask); #elif defined(CONFIG_SCHED_SMT) cpumask_t mask = per_cpu(cpu_sibling_map, cpu); cpus_and(mask, mask, *cpu_map); group = first_cpu(mask); #else group = cpu; #endif if (sg) *sg = &per_cpu(sched_group_phys, group); return group; } #ifdef CONFIG_NUMA /* * The init_sched_build_groups can't handle what we want to do with node * groups, so roll our own. Now each node has its own list of groups which * gets dynamically allocated. */ static DEFINE_PER_CPU(struct sched_domain, node_domains); static struct sched_group **sched_group_nodes_bycpu[NR_CPUS]; static DEFINE_PER_CPU(struct sched_domain, allnodes_domains); static DEFINE_PER_CPU(struct sched_group, sched_group_allnodes); static int cpu_to_allnodes_group(int cpu, const cpumask_t *cpu_map, struct sched_group **sg) { cpumask_t nodemask = node_to_cpumask(cpu_to_node(cpu)); int group; cpus_and(nodemask, nodemask, *cpu_map); group = first_cpu(nodemask); if (sg) *sg = &per_cpu(sched_group_allnodes, group); return group; } static void init_numa_sched_groups_power(struct sched_group *group_head) { struct sched_group *sg = group_head; int j; if (!sg) return; do { for_each_cpu_mask(j, sg->cpumask) { struct sched_domain *sd; sd = &per_cpu(phys_domains, j); if (j != first_cpu(sd->groups->cpumask)) { /* * Only add "power" once for each * physical package. */ continue; } sg_inc_cpu_power(sg, sd->groups->__cpu_power); } sg = sg->next; } while (sg != group_head); } #endif #ifdef CONFIG_NUMA /* Free memory allocated for various sched_group structures */ static void free_sched_groups(const cpumask_t *cpu_map) { int cpu, i; for_each_cpu_mask(cpu, *cpu_map) { struct sched_group **sched_group_nodes = sched_group_nodes_bycpu[cpu]; if (!sched_group_nodes) continue; for (i = 0; i < MAX_NUMNODES; i++) { cpumask_t nodemask = node_to_cpumask(i); struct sched_group *oldsg, *sg = sched_group_nodes[i]; cpus_and(nodemask, nodemask, *cpu_map); if (cpus_empty(nodemask)) continue; if (sg == NULL) continue; sg = sg->next; next_sg: oldsg = sg; sg = sg->next; kfree(oldsg); if (oldsg != sched_group_nodes[i]) goto next_sg; } kfree(sched_group_nodes); sched_group_nodes_bycpu[cpu] = NULL; } } #else static void free_sched_groups(const cpumask_t *cpu_map) { } #endif /* * Initialize sched groups cpu_power. * * cpu_power indicates the capacity of sched group, which is used while * distributing the load between different sched groups in a sched domain. * Typically cpu_power for all the groups in a sched domain will be same unless * there are asymmetries in the topology. If there are asymmetries, group * having more cpu_power will pickup more load compared to the group having * less cpu_power. * * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents * the maximum number of tasks a group can handle in the presence of other idle * or lightly loaded groups in the same sched domain. */ static void init_sched_groups_power(int cpu, struct sched_domain *sd) { struct sched_domain *child; struct sched_group *group; WARN_ON(!sd || !sd->groups); if (cpu != first_cpu(sd->groups->cpumask)) return; child = sd->child; sd->groups->__cpu_power = 0; /* * For perf policy, if the groups in child domain share resources * (for example cores sharing some portions of the cache hierarchy * or SMT), then set this domain groups cpu_power such that each group * can handle only one task, when there are other idle groups in the * same sched domain. */ if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) && (child->flags & (SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) { sg_inc_cpu_power(sd->groups, SCHED_LOAD_SCALE); return; } /* * add cpu_power of each child group to this groups cpu_power */ group = child->groups; do { sg_inc_cpu_power(sd->groups, group->__cpu_power); group = group->next; } while (group != child->groups); } /* * Build sched domains for a given set of cpus and attach the sched domains * to the individual cpus */ static int build_sched_domains(const cpumask_t *cpu_map) { int i; #ifdef CONFIG_NUMA struct sched_group **sched_group_nodes = NULL; int sd_allnodes = 0; /* * Allocate the per-node list of sched groups */ sched_group_nodes = kcalloc(MAX_NUMNODES, sizeof(struct sched_group *), GFP_KERNEL); if (!sched_group_nodes) { printk(KERN_WARNING "Can not alloc sched group node list\n"); return -ENOMEM; } sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes; #endif /* * Set up domains for cpus specified by the cpu_map. */ for_each_cpu_mask(i, *cpu_map) { struct sched_domain *sd = NULL, *p; cpumask_t nodemask = node_to_cpumask(cpu_to_node(i)); cpus_and(nodemask, nodemask, *cpu_map); #ifdef CONFIG_NUMA if (cpus_weight(*cpu_map) > SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) { sd = &per_cpu(allnodes_domains, i); *sd = SD_ALLNODES_INIT; sd->span = *cpu_map; cpu_to_allnodes_group(i, cpu_map, &sd->groups); p = sd; sd_allnodes = 1; } else p = NULL; sd = &per_cpu(node_domains, i); *sd = SD_NODE_INIT; sd->span = sched_domain_node_span(cpu_to_node(i)); sd->parent = p; if (p) p->child = sd; cpus_and(sd->span, sd->span, *cpu_map); #endif p = sd; sd = &per_cpu(phys_domains, i); *sd = SD_CPU_INIT; sd->span = nodemask; sd->parent = p; if (p) p->child = sd; cpu_to_phys_group(i, cpu_map, &sd->groups); #ifdef CONFIG_SCHED_MC p = sd; sd = &per_cpu(core_domains, i); *sd = SD_MC_INIT; sd->span = cpu_coregroup_map(i); cpus_and(sd->span, sd->span, *cpu_map); sd->parent = p; p->child = sd; cpu_to_core_group(i, cpu_map, &sd->groups); #endif #ifdef CONFIG_SCHED_SMT p = sd; sd = &per_cpu(cpu_domains, i); *sd = SD_SIBLING_INIT; sd->span = per_cpu(cpu_sibling_map, i); cpus_and(sd->span, sd->span, *cpu_map); sd->parent = p; p->child = sd; cpu_to_cpu_group(i, cpu_map, &sd->groups); #endif } #ifdef CONFIG_SCHED_SMT /* Set up CPU (sibling) groups */ for_each_cpu_mask(i, *cpu_map) { cpumask_t this_sibling_map = per_cpu(cpu_sibling_map, i); cpus_and(this_sibling_map, this_sibling_map, *cpu_map); if (i != first_cpu(this_sibling_map)) continue; init_sched_build_groups(this_sibling_map, cpu_map, &cpu_to_cpu_group); } #endif #ifdef CONFIG_SCHED_MC /* Set up multi-core groups */ for_each_cpu_mask(i, *cpu_map) { cpumask_t this_core_map = cpu_coregroup_map(i); cpus_and(this_core_map, this_core_map, *cpu_map); if (i != first_cpu(this_core_map)) continue; init_sched_build_groups(this_core_map, cpu_map, &cpu_to_core_group); } #endif /* Set up physical groups */ for (i = 0; i < MAX_NUMNODES; i++) { cpumask_t nodemask = node_to_cpumask(i); cpus_and(nodemask, nodemask, *cpu_map); if (cpus_empty(nodemask)) continue; init_sched_build_groups(nodemask, cpu_map, &cpu_to_phys_group); } #ifdef CONFIG_NUMA /* Set up node groups */ if (sd_allnodes) init_sched_build_groups(*cpu_map, cpu_map, &cpu_to_allnodes_group); for (i = 0; i < MAX_NUMNODES; i++) { /* Set up node groups */ struct sched_group *sg, *prev; cpumask_t nodemask = node_to_cpumask(i); cpumask_t domainspan; cpumask_t covered = CPU_MASK_NONE; int j; cpus_and(nodemask, nodemask, *cpu_map); if (cpus_empty(nodemask)) { sched_group_nodes[i] = NULL; continue; } domainspan = sched_domain_node_span(i); cpus_and(domainspan, domainspan, *cpu_map); sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i); if (!sg) { printk(KERN_WARNING "Can not alloc domain group for " "node %d\n", i); goto error; } sched_group_nodes[i] = sg; for_each_cpu_mask(j, nodemask) { struct sched_domain *sd; sd = &per_cpu(node_domains, j); sd->groups = sg; } sg->__cpu_power = 0; sg->cpumask = nodemask; sg->next = sg; cpus_or(covered, covered, nodemask); prev = sg; for (j = 0; j < MAX_NUMNODES; j++) { cpumask_t tmp, notcovered; int n = (i + j) % MAX_NUMNODES; cpus_complement(notcovered, covered); cpus_and(tmp, notcovered, *cpu_map); cpus_and(tmp, tmp, domainspan); if (cpus_empty(tmp)) break; nodemask = node_to_cpumask(n); cpus_and(tmp, tmp, nodemask); if (cpus_empty(tmp)) continue; sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i); if (!sg) { printk(KERN_WARNING "Can not alloc domain group for node %d\n", j); goto error; } sg->__cpu_power = 0; sg->cpumask = tmp; sg->next = prev->next; cpus_or(covered, covered, tmp); prev->next = sg; prev = sg; } } #endif /* Calculate CPU power for physical packages and nodes */ #ifdef CONFIG_SCHED_SMT for_each_cpu_mask(i, *cpu_map) { struct sched_domain *sd = &per_cpu(cpu_domains, i); init_sched_groups_power(i, sd); } #endif #ifdef CONFIG_SCHED_MC for_each_cpu_mask(i, *cpu_map) { struct sched_domain *sd = &per_cpu(core_domains, i); init_sched_groups_power(i, sd); } #endif for_each_cpu_mask(i, *cpu_map) { struct sched_domain *sd = &per_cpu(phys_domains, i); init_sched_groups_power(i, sd); } #ifdef CONFIG_NUMA for (i = 0; i < MAX_NUMNODES; i++) init_numa_sched_groups_power(sched_group_nodes[i]); if (sd_allnodes) { struct sched_group *sg; cpu_to_allnodes_group(first_cpu(*cpu_map), cpu_map, &sg); init_numa_sched_groups_power(sg); } #endif /* Attach the domains */ for_each_cpu_mask(i, *cpu_map) { struct sched_domain *sd; #ifdef CONFIG_SCHED_SMT sd = &per_cpu(cpu_domains, i); #elif defined(CONFIG_SCHED_MC) sd = &per_cpu(core_domains, i); #else sd = &per_cpu(phys_domains, i); #endif cpu_attach_domain(sd, i); } return 0; #ifdef CONFIG_NUMA error: free_sched_groups(cpu_map); return -ENOMEM; #endif } static cpumask_t *doms_cur; /* current sched domains */ static int ndoms_cur; /* number of sched domains in 'doms_cur' */ /* * Special case: If a kmalloc of a doms_cur partition (array of * cpumask_t) fails, then fallback to a single sched domain, * as determined by the single cpumask_t fallback_doms. */ static cpumask_t fallback_doms; /* * Set up scheduler domains and groups. Callers must hold the hotplug lock. * For now this just excludes isolated cpus, but could be used to * exclude other special cases in the future. */ static int arch_init_sched_domains(const cpumask_t *cpu_map) { int err; ndoms_cur = 1; doms_cur = kmalloc(sizeof(cpumask_t), GFP_KERNEL); if (!doms_cur) doms_cur = &fallback_doms; cpus_andnot(*doms_cur, *cpu_map, cpu_isolated_map); err = build_sched_domains(doms_cur); register_sched_domain_sysctl(); return err; } static void arch_destroy_sched_domains(const cpumask_t *cpu_map) { free_sched_groups(cpu_map); } /* * Detach sched domains from a group of cpus specified in cpu_map * These cpus will now be attached to the NULL domain */ static void detach_destroy_domains(const cpumask_t *cpu_map) { int i; unregister_sched_domain_sysctl(); for_each_cpu_mask(i, *cpu_map) cpu_attach_domain(NULL, i); synchronize_sched(); arch_destroy_sched_domains(cpu_map); } /* * Partition sched domains as specified by the 'ndoms_new' * cpumasks in the array doms_new[] of cpumasks. This compares * doms_new[] to the current sched domain partitioning, doms_cur[]. * It destroys each deleted domain and builds each new domain. * * 'doms_new' is an array of cpumask_t's of length 'ndoms_new'. * The masks don't intersect (don't overlap.) We should setup one * sched domain for each mask. CPUs not in any of the cpumasks will * not be load balanced. If the same cpumask appears both in the * current 'doms_cur' domains and in the new 'doms_new', we can leave * it as it is. * * The passed in 'doms_new' should be kmalloc'd. This routine takes * ownership of it and will kfree it when done with it. If the caller * failed the kmalloc call, then it can pass in doms_new == NULL, * and partition_sched_domains() will fallback to the single partition * 'fallback_doms'. * * Call with hotplug lock held */ void partition_sched_domains(int ndoms_new, cpumask_t *doms_new) { int i, j; /* always unregister in case we don't destroy any domains */ unregister_sched_domain_sysctl(); if (doms_new == NULL) { ndoms_new = 1; doms_new = &fallback_doms; cpus_andnot(doms_new[0], cpu_online_map, cpu_isolated_map); } /* Destroy deleted domains */ for (i = 0; i < ndoms_cur; i++) { for (j = 0; j < ndoms_new; j++) { if (cpus_equal(doms_cur[i], doms_new[j])) goto match1; } /* no match - a current sched domain not in new doms_new[] */ detach_destroy_domains(doms_cur + i); match1: ; } /* Build new domains */ for (i = 0; i < ndoms_new; i++) { for (j = 0; j < ndoms_cur; j++) { if (cpus_equal(doms_new[i], doms_cur[j])) goto match2; } /* no match - add a new doms_new */ build_sched_domains(doms_new + i); match2: ; } /* Remember the new sched domains */ if (doms_cur != &fallback_doms) kfree(doms_cur); doms_cur = doms_new; ndoms_cur = ndoms_new; register_sched_domain_sysctl(); } #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) static int arch_reinit_sched_domains(void) { int err; mutex_lock(&sched_hotcpu_mutex); detach_destroy_domains(&cpu_online_map); err = arch_init_sched_domains(&cpu_online_map); mutex_unlock(&sched_hotcpu_mutex); return err; } static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt) { int ret; if (buf[0] != '0' && buf[0] != '1') return -EINVAL; if (smt) sched_smt_power_savings = (buf[0] == '1'); else sched_mc_power_savings = (buf[0] == '1'); ret = arch_reinit_sched_domains(); return ret ? ret : count; } #ifdef CONFIG_SCHED_MC static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page) { return sprintf(page, "%u\n", sched_mc_power_savings); } static ssize_t sched_mc_power_savings_store(struct sys_device *dev, const char *buf, size_t count) { return sched_power_savings_store(buf, count, 0); } static SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show, sched_mc_power_savings_store); #endif #ifdef CONFIG_SCHED_SMT static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page) { return sprintf(page, "%u\n", sched_smt_power_savings); } static ssize_t sched_smt_power_savings_store(struct sys_device *dev, const char *buf, size_t count) { return sched_power_savings_store(buf, count, 1); } static SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show, sched_smt_power_savings_store); #endif int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls) { int err = 0; #ifdef CONFIG_SCHED_SMT if (smt_capable()) err = sysfs_create_file(&cls->kset.kobj, &attr_sched_smt_power_savings.attr); #endif #ifdef CONFIG_SCHED_MC if (!err && mc_capable()) err = sysfs_create_file(&cls->kset.kobj, &attr_sched_mc_power_savings.attr); #endif return err; } #endif /* * Force a reinitialization of the sched domains hierarchy. The domains * and groups cannot be updated in place without racing with the balancing * code, so we temporarily attach all running cpus to the NULL domain * which will prevent rebalancing while the sched domains are recalculated. */ static int update_sched_domains(struct notifier_block *nfb, unsigned long action, void *hcpu) { switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN: detach_destroy_domains(&cpu_online_map); return NOTIFY_OK; case CPU_UP_CANCELED: case CPU_UP_CANCELED_FROZEN: case CPU_DOWN_FAILED: case CPU_DOWN_FAILED_FROZEN: case CPU_ONLINE: case CPU_ONLINE_FROZEN: case CPU_DEAD: case CPU_DEAD_FROZEN: /* * Fall through and re-initialise the domains. */ break; default: return NOTIFY_DONE; } /* The hotplug lock is already held by cpu_up/cpu_down */ arch_init_sched_domains(&cpu_online_map); return NOTIFY_OK; } void __init sched_init_smp(void) { cpumask_t non_isolated_cpus; mutex_lock(&sched_hotcpu_mutex); arch_init_sched_domains(&cpu_online_map); cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map); if (cpus_empty(non_isolated_cpus)) cpu_set(smp_processor_id(), non_isolated_cpus); mutex_unlock(&sched_hotcpu_mutex); /* XXX: Theoretical race here - CPU may be hotplugged now */ hotcpu_notifier(update_sched_domains, 0); /* Move init over to a non-isolated CPU */ if (set_cpus_allowed(current, non_isolated_cpus) < 0) BUG(); sched_init_granularity(); } #else void __init sched_init_smp(void) { sched_init_granularity(); } #endif /* CONFIG_SMP */ int in_sched_functions(unsigned long addr) { /* Linker adds these: start and end of __sched functions */ extern char __sched_text_start[], __sched_text_end[]; return in_lock_functions(addr) || (addr >= (unsigned long)__sched_text_start && addr < (unsigned long)__sched_text_end); } static void init_cfs_rq(struct cfs_rq *cfs_rq, struct rq *rq) { cfs_rq->tasks_timeline = RB_ROOT; #ifdef CONFIG_FAIR_GROUP_SCHED cfs_rq->rq = rq; #endif cfs_rq->min_vruntime = (u64)(-(1LL << 20)); } void __init sched_init(void) { int highest_cpu = 0; int i, j; for_each_possible_cpu(i) { struct rt_prio_array *array; struct rq *rq; rq = cpu_rq(i); spin_lock_init(&rq->lock); lockdep_set_class(&rq->lock, &rq->rq_lock_key); rq->nr_running = 0; rq->clock = 1; init_cfs_rq(&rq->cfs, rq); #ifdef CONFIG_FAIR_GROUP_SCHED INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); { struct cfs_rq *cfs_rq = &per_cpu(init_cfs_rq, i); struct sched_entity *se = &per_cpu(init_sched_entity, i); init_cfs_rq_p[i] = cfs_rq; init_cfs_rq(cfs_rq, rq); cfs_rq->tg = &init_task_group; list_add(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list); init_sched_entity_p[i] = se; se->cfs_rq = &rq->cfs; se->my_q = cfs_rq; se->load.weight = init_task_group_load; se->load.inv_weight = div64_64(1ULL<<32, init_task_group_load); se->parent = NULL; } init_task_group.shares = init_task_group_load; spin_lock_init(&init_task_group.lock); #endif for (j = 0; j < CPU_LOAD_IDX_MAX; j++) rq->cpu_load[j] = 0; #ifdef CONFIG_SMP rq->sd = NULL; rq->active_balance = 0; rq->next_balance = jiffies; rq->push_cpu = 0; rq->cpu = i; rq->migration_thread = NULL; INIT_LIST_HEAD(&rq->migration_queue); #endif atomic_set(&rq->nr_iowait, 0); array = &rq->rt.active; for (j = 0; j < MAX_RT_PRIO; j++) { INIT_LIST_HEAD(array->queue + j); __clear_bit(j, array->bitmap); } highest_cpu = i; /* delimiter for bitsearch: */ __set_bit(MAX_RT_PRIO, array->bitmap); } set_load_weight(&init_task); #ifdef CONFIG_PREEMPT_NOTIFIERS INIT_HLIST_HEAD(&init_task.preempt_notifiers); #endif #ifdef CONFIG_SMP nr_cpu_ids = highest_cpu + 1; open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL); #endif #ifdef CONFIG_RT_MUTEXES plist_head_init(&init_task.pi_waiters, &init_task.pi_lock); #endif /* * The boot idle thread does lazy MMU switching as well: */ atomic_inc(&init_mm.mm_count); enter_lazy_tlb(&init_mm, current); /* * Make us the idle thread. Technically, schedule() should not be * called from this thread, however somewhere below it might be, * but because we are the idle thread, we just pick up running again * when this runqueue becomes "idle". */ init_idle(current, smp_processor_id()); /* * During early bootup we pretend to be a normal task: */ current->sched_class = &fair_sched_class; } #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP void __might_sleep(char *file, int line) { #ifdef in_atomic static unsigned long prev_jiffy; /* ratelimiting */ if ((in_atomic() || irqs_disabled()) && system_state == SYSTEM_RUNNING && !oops_in_progress) { if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) return; prev_jiffy = jiffies; printk(KERN_ERR "BUG: sleeping function called from invalid" " context at %s:%d\n", file, line); printk("in_atomic():%d, irqs_disabled():%d\n", in_atomic(), irqs_disabled()); debug_show_held_locks(current); if (irqs_disabled()) print_irqtrace_events(current); dump_stack(); } #endif } EXPORT_SYMBOL(__might_sleep); #endif #ifdef CONFIG_MAGIC_SYSRQ static void normalize_task(struct rq *rq, struct task_struct *p) { int on_rq; update_rq_clock(rq); on_rq = p->se.on_rq; if (on_rq) deactivate_task(rq, p, 0); __setscheduler(rq, p, SCHED_NORMAL, 0); if (on_rq) { activate_task(rq, p, 0); resched_task(rq->curr); } } void normalize_rt_tasks(void) { struct task_struct *g, *p; unsigned long flags; struct rq *rq; read_lock_irq(&tasklist_lock); do_each_thread(g, p) { /* * Only normalize user tasks: */ if (!p->mm) continue; p->se.exec_start = 0; #ifdef CONFIG_SCHEDSTATS p->se.wait_start = 0; p->se.sleep_start = 0; p->se.block_start = 0; #endif task_rq(p)->clock = 0; if (!rt_task(p)) { /* * Renice negative nice level userspace * tasks back to 0: */ if (TASK_NICE(p) < 0 && p->mm) set_user_nice(p, 0); continue; } spin_lock_irqsave(&p->pi_lock, flags); rq = __task_rq_lock(p); normalize_task(rq, p); __task_rq_unlock(rq); spin_unlock_irqrestore(&p->pi_lock, flags); } while_each_thread(g, p); read_unlock_irq(&tasklist_lock); } #endif /* CONFIG_MAGIC_SYSRQ */ #ifdef CONFIG_IA64 /* * These functions are only useful for the IA64 MCA handling. * * They can only be called when the whole system has been * stopped - every CPU needs to be quiescent, and no scheduling * activity can take place. Using them for anything else would * be a serious bug, and as a result, they aren't even visible * under any other configuration. */ /** * curr_task - return the current task for a given cpu. * @cpu: the processor in question. * * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! */ struct task_struct *curr_task(int cpu) { return cpu_curr(cpu); } /** * set_curr_task - set the current task for a given cpu. * @cpu: the processor in question. * @p: the task pointer to set. * * Description: This function must only be used when non-maskable interrupts * are serviced on a separate stack. It allows the architecture to switch the * notion of the current task on a cpu in a non-blocking manner. This function * must be called with all CPU's synchronized, and interrupts disabled, the * and caller must save the original value of the current task (see * curr_task() above) and restore that value before reenabling interrupts and * re-starting the system. * * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! */ void set_curr_task(int cpu, struct task_struct *p) { cpu_curr(cpu) = p; } #endif #ifdef CONFIG_FAIR_GROUP_SCHED /* allocate runqueue etc for a new task group */ struct task_group *sched_create_group(void) { struct task_group *tg; struct cfs_rq *cfs_rq; struct sched_entity *se; struct rq *rq; int i; tg = kzalloc(sizeof(*tg), GFP_KERNEL); if (!tg) return ERR_PTR(-ENOMEM); tg->cfs_rq = kzalloc(sizeof(cfs_rq) * NR_CPUS, GFP_KERNEL); if (!tg->cfs_rq) goto err; tg->se = kzalloc(sizeof(se) * NR_CPUS, GFP_KERNEL); if (!tg->se) goto err; for_each_possible_cpu(i) { rq = cpu_rq(i); cfs_rq = kmalloc_node(sizeof(struct cfs_rq), GFP_KERNEL, cpu_to_node(i)); if (!cfs_rq) goto err; se = kmalloc_node(sizeof(struct sched_entity), GFP_KERNEL, cpu_to_node(i)); if (!se) goto err; memset(cfs_rq, 0, sizeof(struct cfs_rq)); memset(se, 0, sizeof(struct sched_entity)); tg->cfs_rq[i] = cfs_rq; init_cfs_rq(cfs_rq, rq); cfs_rq->tg = tg; tg->se[i] = se; se->cfs_rq = &rq->cfs; se->my_q = cfs_rq; se->load.weight = NICE_0_LOAD; se->load.inv_weight = div64_64(1ULL<<32, NICE_0_LOAD); se->parent = NULL; } for_each_possible_cpu(i) { rq = cpu_rq(i); cfs_rq = tg->cfs_rq[i]; list_add_rcu(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list); } tg->shares = NICE_0_LOAD; spin_lock_init(&tg->lock); return tg; err: for_each_possible_cpu(i) { if (tg->cfs_rq) kfree(tg->cfs_rq[i]); if (tg->se) kfree(tg->se[i]); } kfree(tg->cfs_rq); kfree(tg->se); kfree(tg); return ERR_PTR(-ENOMEM); } /* rcu callback to free various structures associated with a task group */ static void free_sched_group(struct rcu_head *rhp) { struct task_group *tg = container_of(rhp, struct task_group, rcu); struct cfs_rq *cfs_rq; struct sched_entity *se; int i; /* now it should be safe to free those cfs_rqs */ for_each_possible_cpu(i) { cfs_rq = tg->cfs_rq[i]; kfree(cfs_rq); se = tg->se[i]; kfree(se); } kfree(tg->cfs_rq); kfree(tg->se); kfree(tg); } /* Destroy runqueue etc associated with a task group */ void sched_destroy_group(struct task_group *tg) { struct cfs_rq *cfs_rq = NULL; int i; for_each_possible_cpu(i) { cfs_rq = tg->cfs_rq[i]; list_del_rcu(&cfs_rq->leaf_cfs_rq_list); } BUG_ON(!cfs_rq); /* wait for possible concurrent references to cfs_rqs complete */ call_rcu(&tg->rcu, free_sched_group); } /* change task's runqueue when it moves between groups. * The caller of this function should have put the task in its new group * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to * reflect its new group. */ void sched_move_task(struct task_struct *tsk) { int on_rq, running; unsigned long flags; struct rq *rq; rq = task_rq_lock(tsk, &flags); if (tsk->sched_class != &fair_sched_class) { set_task_cfs_rq(tsk, task_cpu(tsk)); goto done; } update_rq_clock(rq); running = task_running(rq, tsk); on_rq = tsk->se.on_rq; if (on_rq) { dequeue_task(rq, tsk, 0); if (unlikely(running)) tsk->sched_class->put_prev_task(rq, tsk); } set_task_cfs_rq(tsk, task_cpu(tsk)); if (on_rq) { if (unlikely(running)) tsk->sched_class->set_curr_task(rq); enqueue_task(rq, tsk, 0); } done: task_rq_unlock(rq, &flags); } static void set_se_shares(struct sched_entity *se, unsigned long shares) { struct cfs_rq *cfs_rq = se->cfs_rq; struct rq *rq = cfs_rq->rq; int on_rq; spin_lock_irq(&rq->lock); on_rq = se->on_rq; if (on_rq) dequeue_entity(cfs_rq, se, 0); se->load.weight = shares; se->load.inv_weight = div64_64((1ULL<<32), shares); if (on_rq) enqueue_entity(cfs_rq, se, 0); spin_unlock_irq(&rq->lock); } int sched_group_set_shares(struct task_group *tg, unsigned long shares) { int i; spin_lock(&tg->lock); if (tg->shares == shares) goto done; tg->shares = shares; for_each_possible_cpu(i) set_se_shares(tg->se[i], shares); done: spin_unlock(&tg->lock); return 0; } unsigned long sched_group_shares(struct task_group *tg) { return tg->shares; } #endif /* CONFIG_FAIR_GROUP_SCHED */ #ifdef CONFIG_FAIR_CGROUP_SCHED /* return corresponding task_group object of a cgroup */ static inline struct task_group *cgroup_tg(struct cgroup *cgrp) { return container_of(cgroup_subsys_state(cgrp, cpu_cgroup_subsys_id), struct task_group, css); } static struct cgroup_subsys_state * cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp) { struct task_group *tg; if (!cgrp->parent) { /* This is early initialization for the top cgroup */ init_task_group.css.cgroup = cgrp; return &init_task_group.css; } /* we support only 1-level deep hierarchical scheduler atm */ if (cgrp->parent->parent) return ERR_PTR(-EINVAL); tg = sched_create_group(); if (IS_ERR(tg)) return ERR_PTR(-ENOMEM); /* Bind the cgroup to task_group object we just created */ tg->css.cgroup = cgrp; return &tg->css; } static void cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp) { struct task_group *tg = cgroup_tg(cgrp); sched_destroy_group(tg); } static int cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, struct task_struct *tsk) { /* We don't support RT-tasks being in separate groups */ if (tsk->sched_class != &fair_sched_class) return -EINVAL; return 0; } static void cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, struct cgroup *old_cont, struct task_struct *tsk) { sched_move_task(tsk); } static int cpu_shares_write_uint(struct cgroup *cgrp, struct cftype *cftype, u64 shareval) { return sched_group_set_shares(cgroup_tg(cgrp), shareval); } static u64 cpu_shares_read_uint(struct cgroup *cgrp, struct cftype *cft) { struct task_group *tg = cgroup_tg(cgrp); return (u64) tg->shares; } static u64 cpu_usage_read(struct cgroup *cgrp, struct cftype *cft) { struct task_group *tg = cgroup_tg(cgrp); unsigned long flags; u64 res = 0; int i; for_each_possible_cpu(i) { /* * Lock to prevent races with updating 64-bit counters * on 32-bit arches. */ spin_lock_irqsave(&cpu_rq(i)->lock, flags); res += tg->se[i]->sum_exec_runtime; spin_unlock_irqrestore(&cpu_rq(i)->lock, flags); } /* Convert from ns to ms */ do_div(res, NSEC_PER_MSEC); return res; } static struct cftype cpu_files[] = { { .name = "shares", .read_uint = cpu_shares_read_uint, .write_uint = cpu_shares_write_uint, }, { .name = "usage", .read_uint = cpu_usage_read, }, }; static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont) { return cgroup_add_files(cont, ss, cpu_files, ARRAY_SIZE(cpu_files)); } struct cgroup_subsys cpu_cgroup_subsys = { .name = "cpu", .create = cpu_cgroup_create, .destroy = cpu_cgroup_destroy, .can_attach = cpu_cgroup_can_attach, .attach = cpu_cgroup_attach, .populate = cpu_cgroup_populate, .subsys_id = cpu_cgroup_subsys_id, .early_init = 1, }; #endif /* CONFIG_FAIR_CGROUP_SCHED */