/* * 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 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins, * Thomas Gleixner, Mike Kravetz */ #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 #include #include #include #include #include #include #include #include "sched_cpupri.h" #include "workqueue_sched.h" #define CREATE_TRACE_POINTS #include /* * 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)) /* * Helpers for converting nanosecond timing to jiffy resolution */ #define NS_TO_JIFFIES(TIME) ((unsigned long)(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) /* * single value that denotes runtime == period, ie unlimited time. */ #define RUNTIME_INF ((u64)~0ULL) static inline int rt_policy(int policy) { if (unlikely(policy == SCHED_FIFO || 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]; }; struct rt_bandwidth { /* nests inside the rq lock: */ raw_spinlock_t rt_runtime_lock; ktime_t rt_period; u64 rt_runtime; struct hrtimer rt_period_timer; }; static struct rt_bandwidth def_rt_bandwidth; static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun); static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer) { struct rt_bandwidth *rt_b = container_of(timer, struct rt_bandwidth, rt_period_timer); ktime_t now; int overrun; int idle = 0; for (;;) { now = hrtimer_cb_get_time(timer); overrun = hrtimer_forward(timer, now, rt_b->rt_period); if (!overrun) break; idle = do_sched_rt_period_timer(rt_b, overrun); } return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; } static void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime) { rt_b->rt_period = ns_to_ktime(period); rt_b->rt_runtime = runtime; raw_spin_lock_init(&rt_b->rt_runtime_lock); hrtimer_init(&rt_b->rt_period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); rt_b->rt_period_timer.function = sched_rt_period_timer; } static inline int rt_bandwidth_enabled(void) { return sysctl_sched_rt_runtime >= 0; } static void start_rt_bandwidth(struct rt_bandwidth *rt_b) { ktime_t now; if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF) return; if (hrtimer_active(&rt_b->rt_period_timer)) return; raw_spin_lock(&rt_b->rt_runtime_lock); for (;;) { unsigned long delta; ktime_t soft, hard; if (hrtimer_active(&rt_b->rt_period_timer)) break; now = hrtimer_cb_get_time(&rt_b->rt_period_timer); hrtimer_forward(&rt_b->rt_period_timer, now, rt_b->rt_period); soft = hrtimer_get_softexpires(&rt_b->rt_period_timer); hard = hrtimer_get_expires(&rt_b->rt_period_timer); delta = ktime_to_ns(ktime_sub(hard, soft)); __hrtimer_start_range_ns(&rt_b->rt_period_timer, soft, delta, HRTIMER_MODE_ABS_PINNED, 0); } raw_spin_unlock(&rt_b->rt_runtime_lock); } #ifdef CONFIG_RT_GROUP_SCHED static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b) { hrtimer_cancel(&rt_b->rt_period_timer); } #endif /* * sched_domains_mutex serializes calls to arch_init_sched_domains, * detach_destroy_domains and partition_sched_domains. */ static DEFINE_MUTEX(sched_domains_mutex); #ifdef CONFIG_CGROUP_SCHED #include struct cfs_rq; static LIST_HEAD(task_groups); /* task group related information */ struct task_group { struct cgroup_subsys_state css; #ifdef CONFIG_FAIR_GROUP_SCHED /* 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; #endif #ifdef CONFIG_RT_GROUP_SCHED struct sched_rt_entity **rt_se; struct rt_rq **rt_rq; struct rt_bandwidth rt_bandwidth; #endif struct rcu_head rcu; struct list_head list; struct task_group *parent; struct list_head siblings; struct list_head children; }; #define root_task_group init_task_group /* task_group_lock serializes add/remove of task groups and also changes to * a task group's cpu shares. */ static DEFINE_SPINLOCK(task_group_lock); #ifdef CONFIG_FAIR_GROUP_SCHED #ifdef CONFIG_SMP static int root_task_group_empty(void) { return list_empty(&root_task_group.children); } #endif # define INIT_TASK_GROUP_LOAD NICE_0_LOAD /* * A weight of 0 or 1 can cause arithmetics problems. * A weight of a cfs_rq is the sum of weights of which entities * are queued on this cfs_rq, so a weight of a entity should not be * too large, so as the shares value of a task group. * (The default weight is 1024 - so there's no practical * limitation from this.) */ #define MIN_SHARES 2 #define MAX_SHARES (1UL << 18) static int init_task_group_load = INIT_TASK_GROUP_LOAD; #endif /* Default task group. * Every task in system belong to this group at bootup. */ struct task_group init_task_group; #endif /* CONFIG_CGROUP_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 list_head tasks; struct list_head *balance_iterator; /* * '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, *next, *last; unsigned int 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; struct task_group *tg; /* group that "owns" this runqueue */ #ifdef CONFIG_SMP /* * the part of load.weight contributed by tasks */ unsigned long task_weight; /* * h_load = weight * f(tg) * * Where f(tg) is the recursive weight fraction assigned to * this group. */ unsigned long h_load; /* * this cpu's part of tg->shares */ unsigned long shares; /* * load.weight at the time we set shares */ unsigned long rq_weight; #endif #endif }; /* Real-Time classes' related field in a runqueue: */ struct rt_rq { struct rt_prio_array active; unsigned long rt_nr_running; #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED struct { int curr; /* highest queued rt task prio */ #ifdef CONFIG_SMP int next; /* next highest */ #endif } highest_prio; #endif #ifdef CONFIG_SMP unsigned long rt_nr_migratory; unsigned long rt_nr_total; int overloaded; struct plist_head pushable_tasks; #endif int rt_throttled; u64 rt_time; u64 rt_runtime; /* Nests inside the rq lock: */ raw_spinlock_t rt_runtime_lock; #ifdef CONFIG_RT_GROUP_SCHED unsigned long rt_nr_boosted; struct rq *rq; struct list_head leaf_rt_rq_list; struct task_group *tg; #endif }; #ifdef CONFIG_SMP /* * We add the notion of a root-domain which will be used to define per-domain * variables. Each exclusive cpuset essentially defines an island domain by * fully partitioning the member cpus from any other cpuset. Whenever a new * exclusive cpuset is created, we also create and attach a new root-domain * object. * */ struct root_domain { atomic_t refcount; cpumask_var_t span; cpumask_var_t online; /* * The "RT overload" flag: it gets set if a CPU has more than * one runnable RT task. */ cpumask_var_t rto_mask; atomic_t rto_count; struct cpupri cpupri; }; /* * By default the system creates a single root-domain with all cpus as * members (mimicking the global state we have today). */ static struct root_domain def_root_domain; #endif /* CONFIG_SMP */ /* * 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: */ raw_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 long last_load_update_tick; #ifdef CONFIG_NO_HZ u64 nohz_stamp; unsigned char nohz_balance_kick; #endif unsigned int skip_clock_update; /* capture load from *all* tasks on this cpu: */ struct load_weight load; unsigned long nr_load_updates; u64 nr_switches; struct cfs_rq cfs; struct rt_rq rt; #ifdef CONFIG_FAIR_GROUP_SCHED /* list of leaf cfs_rq on this cpu: */ struct list_head leaf_cfs_rq_list; #endif #ifdef CONFIG_RT_GROUP_SCHED struct list_head leaf_rt_rq_list; #endif /* * 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, *stop; unsigned long next_balance; struct mm_struct *prev_mm; u64 clock; u64 clock_task; atomic_t nr_iowait; #ifdef CONFIG_SMP struct root_domain *rd; struct sched_domain *sd; unsigned long cpu_power; unsigned char idle_at_tick; /* For active balancing */ int post_schedule; int active_balance; int push_cpu; struct cpu_stop_work active_balance_work; /* cpu of this runqueue: */ int cpu; int online; unsigned long avg_load_per_task; u64 rt_avg; u64 age_stamp; u64 idle_stamp; u64 avg_idle; #endif #ifdef CONFIG_IRQ_TIME_ACCOUNTING u64 prev_irq_time; #endif /* calc_load related fields */ unsigned long calc_load_update; long calc_load_active; #ifdef CONFIG_SCHED_HRTICK #ifdef CONFIG_SMP int hrtick_csd_pending; struct call_single_data hrtick_csd; #endif struct hrtimer hrtick_timer; #endif #ifdef CONFIG_SCHEDSTATS /* latency stats */ struct sched_info rq_sched_info; unsigned long long rq_cpu_time; /* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */ u64 skip_clock_max; u64 skip_clock_recent_max; u64 skip_clock_set; unsigned int skip_clock_count; /* sys_sched_yield() stats */ 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 }; static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags); static inline int cpu_of(struct rq *rq) { #ifdef CONFIG_SMP return rq->cpu; #else return 0; #endif } #define rcu_dereference_check_sched_domain(p) \ rcu_dereference_check((p), \ rcu_read_lock_sched_held() || \ lockdep_is_held(&sched_domains_mutex)) /* * 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_check_sched_domain(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) #define raw_rq() (&__raw_get_cpu_var(runqueues)) #ifdef CONFIG_CGROUP_SCHED /* * Return the group to which this tasks belongs. * * We use task_subsys_state_check() and extend the RCU verification * with lockdep_is_held(&task_rq(p)->lock) because cpu_cgroup_attach() * holds that lock for each task it moves into the cgroup. Therefore * by holding that lock, we pin the task to the current cgroup. */ static inline struct task_group *task_group(struct task_struct *p) { struct cgroup_subsys_state *css; css = task_subsys_state_check(p, cpu_cgroup_subsys_id, lockdep_is_held(&task_rq(p)->lock)); return container_of(css, struct task_group, css); } /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */ static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { #ifdef CONFIG_FAIR_GROUP_SCHED p->se.cfs_rq = task_group(p)->cfs_rq[cpu]; p->se.parent = task_group(p)->se[cpu]; #endif #ifdef CONFIG_RT_GROUP_SCHED p->rt.rt_rq = task_group(p)->rt_rq[cpu]; p->rt.parent = task_group(p)->rt_se[cpu]; #endif } #else /* CONFIG_CGROUP_SCHED */ static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { } static inline struct task_group *task_group(struct task_struct *p) { return NULL; } #endif /* CONFIG_CGROUP_SCHED */ static u64 irq_time_cpu(int cpu); static void sched_irq_time_avg_update(struct rq *rq, u64 irq_time); static void clear_skip_clock_update(struct rq *rq) { #ifdef CONFIG_SCHEDSTATS if (unlikely(rq->skip_clock_update)) { u64 skipped = sched_clock_cpu(cpu_of(rq)) - rq->skip_clock_set; rq->skip_clock_max = max(rq->skip_clock_max, skipped); /* reset infrequently to expose changes */ if (!(++rq->skip_clock_count % 10000)) rq->skip_clock_recent_max = 0; rq->skip_clock_recent_max = max(rq->skip_clock_recent_max, skipped); } #endif rq->skip_clock_update = 0; } inline void update_rq_clock(struct rq *rq) { if (!rq->skip_clock_update) { int cpu = cpu_of(rq); u64 irq_time; rq->clock = sched_clock_cpu(cpu); irq_time = irq_time_cpu(cpu); if (rq->clock - irq_time > rq->clock_task) rq->clock_task = rq->clock - irq_time; sched_irq_time_avg_update(rq, irq_time); } clear_skip_clock_update(rq); } /* * 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 /** * runqueue_is_locked * @cpu: the processor in question. * * Returns true if the current cpu runqueue is locked. * This interface allows printk to be called with the runqueue lock * held and know whether or not it is OK to wake up the klogd. */ int runqueue_is_locked(int cpu) { return raw_spin_is_locked(&cpu_rq(cpu)->lock); } /* * Debugging: various feature bits */ #define SCHED_FEAT(name, enabled) \ __SCHED_FEAT_##name , enum { #include "sched_features.h" }; #undef SCHED_FEAT #define SCHED_FEAT(name, enabled) \ (1UL << __SCHED_FEAT_##name) * enabled | const_debug unsigned int sysctl_sched_features = #include "sched_features.h" 0; #undef SCHED_FEAT #ifdef CONFIG_SCHED_DEBUG #define SCHED_FEAT(name, enabled) \ #name , static __read_mostly char *sched_feat_names[] = { #include "sched_features.h" NULL }; #undef SCHED_FEAT static int sched_feat_show(struct seq_file *m, void *v) { int i; for (i = 0; sched_feat_names[i]; i++) { if (!(sysctl_sched_features & (1UL << i))) seq_puts(m, "NO_"); seq_printf(m, "%s ", sched_feat_names[i]); } seq_puts(m, "\n"); return 0; } static ssize_t sched_feat_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { char buf[64]; char *cmp; int neg = 0; int i; if (cnt > 63) cnt = 63; if (copy_from_user(&buf, ubuf, cnt)) return -EFAULT; buf[cnt] = 0; cmp = strstrip(buf); if (strncmp(buf, "NO_", 3) == 0) { neg = 1; cmp += 3; } for (i = 0; sched_feat_names[i]; i++) { if (strcmp(cmp, sched_feat_names[i]) == 0) { if (neg) sysctl_sched_features &= ~(1UL << i); else sysctl_sched_features |= (1UL << i); break; } } if (!sched_feat_names[i]) return -EINVAL; *ppos += cnt; return cnt; } static int sched_feat_open(struct inode *inode, struct file *filp) { return single_open(filp, sched_feat_show, NULL); } static const struct file_operations sched_feat_fops = { .open = sched_feat_open, .write = sched_feat_write, .read = seq_read, .llseek = seq_lseek, .release = single_release, }; static __init int sched_init_debug(void) { debugfs_create_file("sched_features", 0644, NULL, NULL, &sched_feat_fops); return 0; } late_initcall(sched_init_debug); #endif #define sched_feat(x) (sysctl_sched_features & (1UL << __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; /* * ratelimit for updating the group shares. * default: 0.25ms */ unsigned int sysctl_sched_shares_ratelimit = 250000; unsigned int normalized_sysctl_sched_shares_ratelimit = 250000; /* * Inject some fuzzyness into changing the per-cpu group shares * this avoids remote rq-locks at the expense of fairness. * default: 4 */ unsigned int sysctl_sched_shares_thresh = 4; /* * period over which we average the RT time consumption, measured * in ms. * * default: 1s */ const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC; /* * period over which we measure -rt task cpu usage in us. * default: 1s */ unsigned int sysctl_sched_rt_period = 1000000; static __read_mostly int scheduler_running; /* * part of the period that we allow rt tasks to run in us. * default: 0.95s */ int sysctl_sched_rt_runtime = 950000; static inline u64 global_rt_period(void) { return (u64)sysctl_sched_rt_period * NSEC_PER_USEC; } static inline u64 global_rt_runtime(void) { if (sysctl_sched_rt_runtime < 0) return RUNTIME_INF; return (u64)sysctl_sched_rt_runtime * NSEC_PER_USEC; } #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 static inline int task_current(struct rq *rq, struct task_struct *p) { return rq->curr == p; } #ifndef __ARCH_WANT_UNLOCKED_CTXSW static inline int task_running(struct rq *rq, struct task_struct *p) { return task_current(rq, 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_); raw_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 task_current(rq, 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 raw_spin_unlock_irq(&rq->lock); #else raw_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 */ /* * Check whether the task is waking, we use this to synchronize ->cpus_allowed * against ttwu(). */ static inline int task_is_waking(struct task_struct *p) { return unlikely(p->state == TASK_WAKING); } /* * __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) { struct rq *rq; for (;;) { rq = task_rq(p); raw_spin_lock(&rq->lock); if (likely(rq == task_rq(p))) return rq; raw_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); raw_spin_lock(&rq->lock); if (likely(rq == task_rq(p))) return rq; raw_spin_unlock_irqrestore(&rq->lock, *flags); } } static void __task_rq_unlock(struct rq *rq) __releases(rq->lock) { raw_spin_unlock(&rq->lock); } static inline void task_rq_unlock(struct rq *rq, unsigned long *flags) __releases(rq->lock) { raw_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(); raw_spin_lock(&rq->lock); return rq; } #ifdef CONFIG_SCHED_HRTICK /* * Use HR-timers to deliver accurate preemption points. * * Its all a bit involved since we cannot program an hrt while holding the * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a * reschedule event. * * When we get rescheduled we reprogram the hrtick_timer outside of the * rq->lock. */ /* * Use hrtick when: * - enabled by features * - hrtimer is actually high res */ static inline int hrtick_enabled(struct rq *rq) { if (!sched_feat(HRTICK)) return 0; if (!cpu_active(cpu_of(rq))) return 0; return hrtimer_is_hres_active(&rq->hrtick_timer); } static void hrtick_clear(struct rq *rq) { if (hrtimer_active(&rq->hrtick_timer)) hrtimer_cancel(&rq->hrtick_timer); } /* * High-resolution timer tick. * Runs from hardirq context with interrupts disabled. */ static enum hrtimer_restart hrtick(struct hrtimer *timer) { struct rq *rq = container_of(timer, struct rq, hrtick_timer); WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); raw_spin_lock(&rq->lock); update_rq_clock(rq); rq->curr->sched_class->task_tick(rq, rq->curr, 1); raw_spin_unlock(&rq->lock); return HRTIMER_NORESTART; } #ifdef CONFIG_SMP /* * called from hardirq (IPI) context */ static void __hrtick_start(void *arg) { struct rq *rq = arg; raw_spin_lock(&rq->lock); hrtimer_restart(&rq->hrtick_timer); rq->hrtick_csd_pending = 0; raw_spin_unlock(&rq->lock); } /* * Called to set the hrtick timer state. * * called with rq->lock held and irqs disabled */ static void hrtick_start(struct rq *rq, u64 delay) { struct hrtimer *timer = &rq->hrtick_timer; ktime_t time = ktime_add_ns(timer->base->get_time(), delay); hrtimer_set_expires(timer, time); if (rq == this_rq()) { hrtimer_restart(timer); } else if (!rq->hrtick_csd_pending) { __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0); rq->hrtick_csd_pending = 1; } } static int hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu) { int cpu = (int)(long)hcpu; switch (action) { case CPU_UP_CANCELED: case CPU_UP_CANCELED_FROZEN: case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN: case CPU_DEAD: case CPU_DEAD_FROZEN: hrtick_clear(cpu_rq(cpu)); return NOTIFY_OK; } return NOTIFY_DONE; } static __init void init_hrtick(void) { hotcpu_notifier(hotplug_hrtick, 0); } #else /* * Called to set the hrtick timer state. * * called with rq->lock held and irqs disabled */ static void hrtick_start(struct rq *rq, u64 delay) { __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0, HRTIMER_MODE_REL_PINNED, 0); } static inline void init_hrtick(void) { } #endif /* CONFIG_SMP */ static void init_rq_hrtick(struct rq *rq) { #ifdef CONFIG_SMP rq->hrtick_csd_pending = 0; rq->hrtick_csd.flags = 0; rq->hrtick_csd.func = __hrtick_start; rq->hrtick_csd.info = rq; #endif hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); rq->hrtick_timer.function = hrtick; } #else /* CONFIG_SCHED_HRTICK */ static inline void hrtick_clear(struct rq *rq) { } static inline void init_rq_hrtick(struct rq *rq) { } static inline void init_hrtick(void) { } #endif /* CONFIG_SCHED_HRTICK */ /* * 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_raw_spin_locked(&task_rq(p)->lock); if (test_tsk_need_resched(p)) return; set_tsk_need_resched(p); 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 (!raw_spin_trylock_irqsave(&rq->lock, flags)) return; resched_task(cpu_curr(cpu)); raw_spin_unlock_irqrestore(&rq->lock, flags); } #ifdef CONFIG_NO_HZ /* * In the semi idle case, use the nearest busy cpu for migrating timers * from an idle cpu. This is good for power-savings. * * We don't do similar optimization for completely idle system, as * selecting an idle cpu will add more delays to the timers than intended * (as that cpu's timer base may not be uptodate wrt jiffies etc). */ int get_nohz_timer_target(void) { int cpu = smp_processor_id(); int i; struct sched_domain *sd; for_each_domain(cpu, sd) { for_each_cpu(i, sched_domain_span(sd)) if (!idle_cpu(i)) return i; } return cpu; } /* * When add_timer_on() enqueues a timer into the timer wheel of an * idle CPU then this timer might expire before the next timer event * which is scheduled to wake up that CPU. In case of a completely * idle system the next event might even be infinite time into the * future. wake_up_idle_cpu() ensures that the CPU is woken up and * leaves the inner idle loop so the newly added timer is taken into * account when the CPU goes back to idle and evaluates the timer * wheel for the next timer event. */ void wake_up_idle_cpu(int cpu) { struct rq *rq = cpu_rq(cpu); if (cpu == smp_processor_id()) return; /* * This is safe, as this function is called with the timer * wheel base lock of (cpu) held. When the CPU is on the way * to idle and has not yet set rq->curr to idle then it will * be serialized on the timer wheel base lock and take the new * timer into account automatically. */ if (rq->curr != rq->idle) return; /* * We can set TIF_RESCHED on the idle task of the other CPU * lockless. The worst case is that the other CPU runs the * idle task through an additional NOOP schedule() */ set_tsk_need_resched(rq->idle); /* NEED_RESCHED must be visible before we test polling */ smp_mb(); if (!tsk_is_polling(rq->idle)) smp_send_reschedule(cpu); } #endif /* CONFIG_NO_HZ */ static u64 sched_avg_period(void) { return (u64)sysctl_sched_time_avg * NSEC_PER_MSEC / 2; } static void sched_avg_update(struct rq *rq) { s64 period = sched_avg_period(); while ((s64)(rq->clock - rq->age_stamp) > period) { /* * Inline assembly required to prevent the compiler * optimising this loop into a divmod call. * See __iter_div_u64_rem() for another example of this. */ asm("" : "+rm" (rq->age_stamp)); rq->age_stamp += period; rq->rt_avg /= 2; } } static void sched_rt_avg_update(struct rq *rq, u64 rt_delta) { rq->rt_avg += rt_delta; sched_avg_update(rq); } #else /* !CONFIG_SMP */ static void resched_task(struct task_struct *p) { assert_raw_spin_locked(&task_rq(p)->lock); set_tsk_need_resched(p); } static void sched_rt_avg_update(struct rq *rq, u64 rt_delta) { } static void sched_avg_update(struct rq *rq) { } #endif /* CONFIG_SMP */ #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)) /* * delta *= weight / lw */ static unsigned long calc_delta_mine(unsigned long delta_exec, unsigned long weight, struct load_weight *lw) { u64 tmp; if (!lw->inv_weight) { if (BITS_PER_LONG > 32 && unlikely(lw->weight >= WMULT_CONST)) lw->inv_weight = 1; else lw->inv_weight = 1 + (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 void update_load_add(struct load_weight *lw, unsigned long inc) { lw->weight += inc; lw->inv_weight = 0; } static inline void update_load_sub(struct load_weight *lw, unsigned long dec) { lw->weight -= dec; lw->inv_weight = 0; } /* * 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 3 #define WMULT_IDLEPRIO 1431655765 /* * 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, }; /* Time spent by the tasks of the cpu accounting group executing in ... */ enum cpuacct_stat_index { CPUACCT_STAT_USER, /* ... user mode */ CPUACCT_STAT_SYSTEM, /* ... kernel mode */ CPUACCT_STAT_NSTATS, }; #ifdef CONFIG_CGROUP_CPUACCT static void cpuacct_charge(struct task_struct *tsk, u64 cputime); static void cpuacct_update_stats(struct task_struct *tsk, enum cpuacct_stat_index idx, cputime_t val); #else static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {} static inline void cpuacct_update_stats(struct task_struct *tsk, enum cpuacct_stat_index idx, cputime_t val) {} #endif static inline void inc_cpu_load(struct rq *rq, unsigned long load) { update_load_add(&rq->load, load); } static inline void dec_cpu_load(struct rq *rq, unsigned long load) { update_load_sub(&rq->load, load); } #if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) || defined(CONFIG_RT_GROUP_SCHED) typedef int (*tg_visitor)(struct task_group *, void *); /* * Iterate the full tree, calling @down when first entering a node and @up when * leaving it for the final time. */ static int walk_tg_tree(tg_visitor down, tg_visitor up, void *data) { struct task_group *parent, *child; int ret; rcu_read_lock(); parent = &root_task_group; down: ret = (*down)(parent, data); if (ret) goto out_unlock; list_for_each_entry_rcu(child, &parent->children, siblings) { parent = child; goto down; up: continue; } ret = (*up)(parent, data); if (ret) goto out_unlock; child = parent; parent = parent->parent; if (parent) goto up; out_unlock: rcu_read_unlock(); return ret; } static int tg_nop(struct task_group *tg, void *data) { return 0; } #endif #ifdef CONFIG_SMP /* Used instead of source_load when we know the type == 0 */ static unsigned long weighted_cpuload(const int cpu) { return cpu_rq(cpu)->load.weight; } /* * 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 || !sched_feat(LB_BIAS)) 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 || !sched_feat(LB_BIAS)) return total; return max(rq->cpu_load[type-1], total); } static unsigned long power_of(int cpu) { return cpu_rq(cpu)->cpu_power; } static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd); static unsigned long cpu_avg_load_per_task(int cpu) { struct rq *rq = cpu_rq(cpu); unsigned long nr_running = ACCESS_ONCE(rq->nr_running); if (nr_running) rq->avg_load_per_task = rq->load.weight / nr_running; else rq->avg_load_per_task = 0; return rq->avg_load_per_task; } #ifdef CONFIG_FAIR_GROUP_SCHED static __read_mostly unsigned long __percpu *update_shares_data; static void __set_se_shares(struct sched_entity *se, unsigned long shares); /* * Calculate and set the cpu's group shares. */ static void update_group_shares_cpu(struct task_group *tg, int cpu, unsigned long sd_shares, unsigned long sd_rq_weight, unsigned long *usd_rq_weight) { unsigned long shares, rq_weight; int boost = 0; rq_weight = usd_rq_weight[cpu]; if (!rq_weight) { boost = 1; rq_weight = NICE_0_LOAD; } /* * \Sum_j shares_j * rq_weight_i * shares_i = ----------------------------- * \Sum_j rq_weight_j */ shares = (sd_shares * rq_weight) / sd_rq_weight; shares = clamp_t(unsigned long, shares, MIN_SHARES, MAX_SHARES); if (abs(shares - tg->se[cpu]->load.weight) > sysctl_sched_shares_thresh) { struct rq *rq = cpu_rq(cpu); unsigned long flags; raw_spin_lock_irqsave(&rq->lock, flags); tg->cfs_rq[cpu]->rq_weight = boost ? 0 : rq_weight; tg->cfs_rq[cpu]->shares = boost ? 0 : shares; __set_se_shares(tg->se[cpu], shares); raw_spin_unlock_irqrestore(&rq->lock, flags); } } /* * Re-compute the task group their per cpu shares over the given domain. * This needs to be done in a bottom-up fashion because the rq weight of a * parent group depends on the shares of its child groups. */ static int tg_shares_up(struct task_group *tg, void *data) { unsigned long weight, rq_weight = 0, sum_weight = 0, shares = 0; unsigned long *usd_rq_weight; struct sched_domain *sd = data; unsigned long flags; int i; if (!tg->se[0]) return 0; local_irq_save(flags); usd_rq_weight = per_cpu_ptr(update_shares_data, smp_processor_id()); for_each_cpu(i, sched_domain_span(sd)) { weight = tg->cfs_rq[i]->load.weight; usd_rq_weight[i] = weight; rq_weight += weight; /* * If there are currently no tasks on the cpu pretend there * is one of average load so that when a new task gets to * run here it will not get delayed by group starvation. */ if (!weight) weight = NICE_0_LOAD; sum_weight += weight; shares += tg->cfs_rq[i]->shares; } if (!rq_weight) rq_weight = sum_weight; if ((!shares && rq_weight) || shares > tg->shares) shares = tg->shares; if (!sd->parent || !(sd->parent->flags & SD_LOAD_BALANCE)) shares = tg->shares; for_each_cpu(i, sched_domain_span(sd)) update_group_shares_cpu(tg, i, shares, rq_weight, usd_rq_weight); local_irq_restore(flags); return 0; } /* * Compute the cpu's hierarchical load factor for each task group. * This needs to be done in a top-down fashion because the load of a child * group is a fraction of its parents load. */ static int tg_load_down(struct task_group *tg, void *data) { unsigned long load; long cpu = (long)data; if (!tg->parent) { load = cpu_rq(cpu)->load.weight; } else { load = tg->parent->cfs_rq[cpu]->h_load; load *= tg->cfs_rq[cpu]->shares; load /= tg->parent->cfs_rq[cpu]->load.weight + 1; } tg->cfs_rq[cpu]->h_load = load; return 0; } static void update_shares(struct sched_domain *sd) { s64 elapsed; u64 now; if (root_task_group_empty()) return; now = local_clock(); elapsed = now - sd->last_update; if (elapsed >= (s64)(u64)sysctl_sched_shares_ratelimit) { sd->last_update = now; walk_tg_tree(tg_nop, tg_shares_up, sd); } } static void update_h_load(long cpu) { walk_tg_tree(tg_load_down, tg_nop, (void *)cpu); } #else static inline void update_shares(struct sched_domain *sd) { } #endif #ifdef CONFIG_PREEMPT static void double_rq_lock(struct rq *rq1, struct rq *rq2); /* * fair double_lock_balance: Safely acquires both rq->locks in a fair * way at the expense of forcing extra atomic operations in all * invocations. This assures that the double_lock is acquired using the * same underlying policy as the spinlock_t on this architecture, which * reduces latency compared to the unfair variant below. However, it * also adds more overhead and therefore may reduce throughput. */ static inline int _double_lock_balance(struct rq *this_rq, struct rq *busiest) __releases(this_rq->lock) __acquires(busiest->lock) __acquires(this_rq->lock) { raw_spin_unlock(&this_rq->lock); double_rq_lock(this_rq, busiest); return 1; } #else /* * Unfair double_lock_balance: Optimizes throughput at the expense of * latency by eliminating extra atomic operations when the locks are * already in proper order on entry. This favors lower cpu-ids and will * grant the double lock to lower cpus over higher ids under contention, * regardless of entry order into the function. */ static int _double_lock_balance(struct rq *this_rq, struct rq *busiest) __releases(this_rq->lock) __acquires(busiest->lock) __acquires(this_rq->lock) { int ret = 0; if (unlikely(!raw_spin_trylock(&busiest->lock))) { if (busiest < this_rq) { raw_spin_unlock(&this_rq->lock); raw_spin_lock(&busiest->lock); raw_spin_lock_nested(&this_rq->lock, SINGLE_DEPTH_NESTING); ret = 1; } else raw_spin_lock_nested(&busiest->lock, SINGLE_DEPTH_NESTING); } return ret; } #endif /* CONFIG_PREEMPT */ /* * double_lock_balance - lock the busiest runqueue, this_rq is locked already. */ static int double_lock_balance(struct rq *this_rq, struct rq *busiest) { if (unlikely(!irqs_disabled())) { /* printk() doesn't work good under rq->lock */ raw_spin_unlock(&this_rq->lock); BUG_ON(1); } return _double_lock_balance(this_rq, busiest); } static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest) __releases(busiest->lock) { raw_spin_unlock(&busiest->lock); lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_); } /* * 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) { raw_spin_lock(&rq1->lock); __acquire(rq2->lock); /* Fake it out ;) */ } else { if (rq1 < rq2) { raw_spin_lock(&rq1->lock); raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING); } else { raw_spin_lock(&rq2->lock); raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING); } } } /* * 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) { raw_spin_unlock(&rq1->lock); if (rq1 != rq2) raw_spin_unlock(&rq2->lock); else __release(rq2->lock); } #endif #ifdef CONFIG_FAIR_GROUP_SCHED static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares) { #ifdef CONFIG_SMP cfs_rq->shares = shares; #endif } #endif static void calc_load_account_idle(struct rq *this_rq); static void update_sysctl(void); static int get_update_sysctl_factor(void); static void update_cpu_load(struct rq *this_rq); static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu) { set_task_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 } static const struct sched_class rt_sched_class; #define sched_class_highest (&stop_sched_class) #define for_each_class(class) \ for (class = sched_class_highest; class; class = class->next) #include "sched_stats.h" static void inc_nr_running(struct rq *rq) { rq->nr_running++; } static void dec_nr_running(struct rq *rq) { rq->nr_running--; } static void set_load_weight(struct task_struct *p) { /* * 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 flags) { update_rq_clock(rq); sched_info_queued(p); p->sched_class->enqueue_task(rq, p, flags); p->se.on_rq = 1; } static void dequeue_task(struct rq *rq, struct task_struct *p, int flags) { update_rq_clock(rq); sched_info_dequeued(p); p->sched_class->dequeue_task(rq, p, flags); p->se.on_rq = 0; } /* * activate_task - move a task to the runqueue. */ static void activate_task(struct rq *rq, struct task_struct *p, int flags) { if (task_contributes_to_load(p)) rq->nr_uninterruptible--; enqueue_task(rq, p, flags); inc_nr_running(rq); } /* * deactivate_task - remove a task from the runqueue. */ static void deactivate_task(struct rq *rq, struct task_struct *p, int flags) { if (task_contributes_to_load(p)) rq->nr_uninterruptible++; dequeue_task(rq, p, flags); dec_nr_running(rq); } #ifdef CONFIG_IRQ_TIME_ACCOUNTING /* * There are no locks covering percpu hardirq/softirq time. * They are only modified in account_system_vtime, on corresponding CPU * with interrupts disabled. So, writes are safe. * They are read and saved off onto struct rq in update_rq_clock(). * This may result in other CPU reading this CPU's irq time and can * race with irq/account_system_vtime on this CPU. We would either get old * or new value (or semi updated value on 32 bit) with a side effect of * accounting a slice of irq time to wrong task when irq is in progress * while we read rq->clock. That is a worthy compromise in place of having * locks on each irq in account_system_time. */ static DEFINE_PER_CPU(u64, cpu_hardirq_time); static DEFINE_PER_CPU(u64, cpu_softirq_time); static DEFINE_PER_CPU(u64, irq_start_time); static int sched_clock_irqtime; void enable_sched_clock_irqtime(void) { sched_clock_irqtime = 1; } void disable_sched_clock_irqtime(void) { sched_clock_irqtime = 0; } static u64 irq_time_cpu(int cpu) { if (!sched_clock_irqtime) return 0; return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu); } void account_system_vtime(struct task_struct *curr) { unsigned long flags; int cpu; u64 now, delta; if (!sched_clock_irqtime) return; local_irq_save(flags); cpu = smp_processor_id(); now = sched_clock_cpu(cpu); delta = now - per_cpu(irq_start_time, cpu); per_cpu(irq_start_time, cpu) = now; /* * We do not account for softirq time from ksoftirqd here. * We want to continue accounting softirq time to ksoftirqd thread * in that case, so as not to confuse scheduler with a special task * that do not consume any time, but still wants to run. */ if (hardirq_count()) per_cpu(cpu_hardirq_time, cpu) += delta; else if (in_serving_softirq() && !(curr->flags & PF_KSOFTIRQD)) per_cpu(cpu_softirq_time, cpu) += delta; local_irq_restore(flags); } EXPORT_SYMBOL_GPL(account_system_vtime); static void sched_irq_time_avg_update(struct rq *rq, u64 curr_irq_time) { if (sched_clock_irqtime && sched_feat(NONIRQ_POWER)) { u64 delta_irq = curr_irq_time - rq->prev_irq_time; rq->prev_irq_time = curr_irq_time; sched_rt_avg_update(rq, delta_irq); } } #else static u64 irq_time_cpu(int cpu) { return 0; } static void sched_irq_time_avg_update(struct rq *rq, u64 curr_irq_time) { } #endif #include "sched_idletask.c" #include "sched_fair.c" #include "sched_rt.c" #include "sched_stoptask.c" #ifdef CONFIG_SCHED_DEBUG # include "sched_debug.c" #endif void sched_set_stop_task(int cpu, struct task_struct *stop) { struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; struct task_struct *old_stop = cpu_rq(cpu)->stop; if (stop) { /* * Make it appear like a SCHED_FIFO task, its something * userspace knows about and won't get confused about. * * Also, it will make PI more or less work without too * much confusion -- but then, stop work should not * rely on PI working anyway. */ sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); stop->sched_class = &stop_sched_class; } cpu_rq(cpu)->stop = stop; if (old_stop) { /* * Reset it back to a normal scheduling class so that * it can die in pieces. */ old_stop->sched_class = &rt_sched_class; } } /* * __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; } /** * 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; } static inline void check_class_changed(struct rq *rq, struct task_struct *p, const struct sched_class *prev_class, int oldprio, int running) { if (prev_class != p->sched_class) { if (prev_class->switched_from) prev_class->switched_from(rq, p, running); p->sched_class->switched_to(rq, p, running); } else p->sched_class->prio_changed(rq, p, oldprio, running); } static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) { const struct sched_class *class; if (p->sched_class == rq->curr->sched_class) { rq->curr->sched_class->check_preempt_curr(rq, p, flags); } else { for_each_class(class) { if (class == rq->curr->sched_class) break; if (class == p->sched_class) { resched_task(rq->curr); break; } } } /* * A queue event has occurred, and we're going to schedule. In * this case, we can save a useless back to back clock update. */ if (rq->curr->se.on_rq && test_tsk_need_resched(rq->curr)) { schedstat_set(rq->skip_clock_set, sched_clock_cpu(cpu_of(rq))); rq->skip_clock_update = 1; } } #ifdef CONFIG_SMP /* * Is this task likely cache-hot: */ static 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 (unlikely(p->policy == SCHED_IDLE)) return 0; /* * Buddy candidates are cache hot: */ if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running && (&p->se == cfs_rq_of(&p->se)->next || &p->se == cfs_rq_of(&p->se)->last)) return 1; 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) { #ifdef CONFIG_SCHED_DEBUG /* * We should never call set_task_cpu() on a blocked task, * ttwu() will sort out the placement. */ WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)); #endif trace_sched_migrate_task(p, new_cpu); if (task_cpu(p) != new_cpu) { p->se.nr_migrations++; perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 1, NULL, 0); } __set_task_cpu(p, new_cpu); } struct migration_arg { struct task_struct *task; int dest_cpu; }; static int migration_cpu_stop(void *data); /* * The task's runqueue lock must be held. * Returns true if you have to wait for migration thread. */ static bool migrate_task(struct task_struct *p, int dest_cpu) { struct rq *rq = task_rq(p); /* * If the task is not on a runqueue (and not running), then * the next wake-up will properly place the task. */ return p->se.on_rq || task_running(rq, p); } /* * wait_task_inactive - wait for a thread to unschedule. * * If @match_state is nonzero, it's the @p->state value just checked and * not expected to change. If it changes, i.e. @p might have woken up, * then return zero. When we succeed in waiting for @p to be off its CPU, * we return a positive number (its total switch count). If a second call * a short while later returns the same number, the caller can be sure that * @p has remained unscheduled the whole time. * * 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. */ unsigned long wait_task_inactive(struct task_struct *p, long match_state) { unsigned long flags; int running, on_rq; unsigned long ncsw; 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)) { if (match_state && unlikely(p->state != match_state)) return 0; 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); trace_sched_wait_task(p); running = task_running(rq, p); on_rq = p->se.on_rq; ncsw = 0; if (!match_state || p->state == match_state) ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ task_rq_unlock(rq, &flags); /* * If it changed from the expected state, bail out now. */ if (unlikely(!ncsw)) break; /* * 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 was 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; } return ncsw; } /*** * 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(); } EXPORT_SYMBOL_GPL(kick_process); #endif /* CONFIG_SMP */ /** * task_oncpu_function_call - call a function on the cpu on which a task runs * @p: the task to evaluate * @func: the function to be called * @info: the function call argument * * Calls the function @func when the task is currently running. This might * be on the current CPU, which just calls the function directly */ void task_oncpu_function_call(struct task_struct *p, void (*func) (void *info), void *info) { int cpu; preempt_disable(); cpu = task_cpu(p); if (task_curr(p)) smp_call_function_single(cpu, func, info, 1); preempt_enable(); } #ifdef CONFIG_SMP /* * ->cpus_allowed is protected by either TASK_WAKING or rq->lock held. */ static int select_fallback_rq(int cpu, struct task_struct *p) { int dest_cpu; const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu)); /* Look for allowed, online CPU in same node. */ for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask) if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed)) return dest_cpu; /* Any allowed, online CPU? */ dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask); if (dest_cpu < nr_cpu_ids) return dest_cpu; /* No more Mr. Nice Guy. */ if (unlikely(dest_cpu >= nr_cpu_ids)) { dest_cpu = cpuset_cpus_allowed_fallback(p); /* * 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, cpu); } } return dest_cpu; } /* * The caller (fork, wakeup) owns TASK_WAKING, ->cpus_allowed is stable. */ static inline int select_task_rq(struct rq *rq, struct task_struct *p, int sd_flags, int wake_flags) { int cpu = p->sched_class->select_task_rq(rq, p, sd_flags, wake_flags); /* * In order not to call set_task_cpu() on a blocking task we need * to rely on ttwu() to place the task on a valid ->cpus_allowed * cpu. * * Since this is common to all placement strategies, this lives here. * * [ this allows ->select_task() to simply return task_cpu(p) and * not worry about this generic constraint ] */ if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) || !cpu_online(cpu))) cpu = select_fallback_rq(task_cpu(p), p); return cpu; } static void update_avg(u64 *avg, u64 sample) { s64 diff = sample - *avg; *avg += diff >> 3; } #endif static inline void ttwu_activate(struct task_struct *p, struct rq *rq, bool is_sync, bool is_migrate, bool is_local, unsigned long en_flags) { schedstat_inc(p, se.statistics.nr_wakeups); if (is_sync) schedstat_inc(p, se.statistics.nr_wakeups_sync); if (is_migrate) schedstat_inc(p, se.statistics.nr_wakeups_migrate); if (is_local) schedstat_inc(p, se.statistics.nr_wakeups_local); else schedstat_inc(p, se.statistics.nr_wakeups_remote); activate_task(rq, p, en_flags); } static inline void ttwu_post_activation(struct task_struct *p, struct rq *rq, int wake_flags, bool success) { trace_sched_wakeup(p, success); check_preempt_curr(rq, p, wake_flags); p->state = TASK_RUNNING; #ifdef CONFIG_SMP if (p->sched_class->task_woken) p->sched_class->task_woken(rq, p); if (unlikely(rq->idle_stamp)) { u64 delta = rq->clock - rq->idle_stamp; u64 max = 2*sysctl_sched_migration_cost; if (delta > max) rq->avg_idle = max; else update_avg(&rq->avg_idle, delta); rq->idle_stamp = 0; } #endif /* if a worker is waking up, notify workqueue */ if ((p->flags & PF_WQ_WORKER) && success) wq_worker_waking_up(p, cpu_of(rq)); } /** * try_to_wake_up - wake up a thread * @p: the thread to be awakened * @state: the mask of task states that can be woken * @wake_flags: wake modifier flags (WF_*) * * 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 %true if @p was woken up, %false if it was already running * or @state didn't match @p's state. */ static int try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) { int cpu, orig_cpu, this_cpu, success = 0; unsigned long flags; unsigned long en_flags = ENQUEUE_WAKEUP; struct rq *rq; this_cpu = get_cpu(); smp_wmb(); rq = task_rq_lock(p, &flags); if (!(p->state & state)) goto out; if (p->se.on_rq) goto out_running; cpu = task_cpu(p); orig_cpu = cpu; #ifdef CONFIG_SMP if (unlikely(task_running(rq, p))) goto out_activate; /* * In order to handle concurrent wakeups and release the rq->lock * we put the task in TASK_WAKING state. * * First fix up the nr_uninterruptible count: */ if (task_contributes_to_load(p)) { if (likely(cpu_online(orig_cpu))) rq->nr_uninterruptible--; else this_rq()->nr_uninterruptible--; } p->state = TASK_WAKING; if (p->sched_class->task_waking) { p->sched_class->task_waking(rq, p); en_flags |= ENQUEUE_WAKING; } cpu = select_task_rq(rq, p, SD_BALANCE_WAKE, wake_flags); if (cpu != orig_cpu) set_task_cpu(p, cpu); __task_rq_unlock(rq); rq = cpu_rq(cpu); raw_spin_lock(&rq->lock); /* * We migrated the task without holding either rq->lock, however * since the task is not on the task list itself, nobody else * will try and migrate the task, hence the rq should match the * cpu we just moved it to. */ WARN_ON(task_cpu(p) != cpu); WARN_ON(p->state != TASK_WAKING); #ifdef CONFIG_SCHEDSTATS schedstat_inc(rq, ttwu_count); if (cpu == this_cpu) schedstat_inc(rq, ttwu_local); else { struct sched_domain *sd; for_each_domain(this_cpu, sd) { if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { schedstat_inc(sd, ttwu_wake_remote); break; } } } #endif /* CONFIG_SCHEDSTATS */ out_activate: #endif /* CONFIG_SMP */ ttwu_activate(p, rq, wake_flags & WF_SYNC, orig_cpu != cpu, cpu == this_cpu, en_flags); success = 1; out_running: ttwu_post_activation(p, rq, wake_flags, success); out: task_rq_unlock(rq, &flags); put_cpu(); return success; } /** * try_to_wake_up_local - try to wake up a local task with rq lock held * @p: the thread to be awakened * * Put @p on the run-queue if it's not alredy there. The caller must * ensure that this_rq() is locked, @p is bound to this_rq() and not * the current task. this_rq() stays locked over invocation. */ static void try_to_wake_up_local(struct task_struct *p) { struct rq *rq = task_rq(p); bool success = false; BUG_ON(rq != this_rq()); BUG_ON(p == current); lockdep_assert_held(&rq->lock); if (!(p->state & TASK_NORMAL)) return; if (!p->se.on_rq) { if (likely(!task_running(rq, p))) { schedstat_inc(rq, ttwu_count); schedstat_inc(rq, ttwu_local); } ttwu_activate(p, rq, false, false, true, ENQUEUE_WAKEUP); success = true; } ttwu_post_activation(p, rq, 0, success); } /** * wake_up_process - Wake up a specific process * @p: The process to be woken up. * * Attempt to wake up the nominated process and move it to the set of runnable * processes. Returns 1 if the process was woken up, 0 if it was already * running. * * It may be assumed that this function implies a write memory barrier before * changing the task state if and only if any tasks are woken up. */ int wake_up_process(struct task_struct *p) { return try_to_wake_up(p, TASK_ALL, 0); } EXPORT_SYMBOL(wake_up_process); int 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; p->se.nr_migrations = 0; #ifdef CONFIG_SCHEDSTATS memset(&p->se.statistics, 0, sizeof(p->se.statistics)); #endif INIT_LIST_HEAD(&p->rt.run_list); p->se.on_rq = 0; INIT_LIST_HEAD(&p->se.group_node); #ifdef CONFIG_PREEMPT_NOTIFIERS INIT_HLIST_HEAD(&p->preempt_notifiers); #endif } /* * fork()/clone()-time setup: */ void sched_fork(struct task_struct *p, int clone_flags) { int cpu = get_cpu(); __sched_fork(p); /* * We mark the process as running here. 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; /* * Revert to default priority/policy on fork if requested. */ if (unlikely(p->sched_reset_on_fork)) { if (p->policy == SCHED_FIFO || p->policy == SCHED_RR) { p->policy = SCHED_NORMAL; p->normal_prio = p->static_prio; } if (PRIO_TO_NICE(p->static_prio) < 0) { p->static_prio = NICE_TO_PRIO(0); p->normal_prio = p->static_prio; set_load_weight(p); } /* * We don't need the reset flag anymore after the fork. It has * fulfilled its duty: */ p->sched_reset_on_fork = 0; } /* * 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 (p->sched_class->task_fork) p->sched_class->task_fork(p); /* * The child is not yet in the pid-hash so no cgroup attach races, * and the cgroup is pinned to this child due to cgroup_fork() * is ran before sched_fork(). * * Silence PROVE_RCU. */ rcu_read_lock(); set_task_cpu(p, cpu); rcu_read_unlock(); #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 plist_node_init(&p->pushable_tasks, MAX_PRIO); 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 wake_up_new_task(struct task_struct *p, unsigned long clone_flags) { unsigned long flags; struct rq *rq; int cpu __maybe_unused = get_cpu(); #ifdef CONFIG_SMP rq = task_rq_lock(p, &flags); p->state = TASK_WAKING; /* * Fork balancing, do it here and not earlier because: * - cpus_allowed can change in the fork path * - any previously selected cpu might disappear through hotplug * * We set TASK_WAKING so that select_task_rq() can drop rq->lock * without people poking at ->cpus_allowed. */ cpu = select_task_rq(rq, p, SD_BALANCE_FORK, 0); set_task_cpu(p, cpu); p->state = TASK_RUNNING; task_rq_unlock(rq, &flags); #endif rq = task_rq_lock(p, &flags); activate_task(rq, p, 0); trace_sched_wakeup_new(p, 1); check_preempt_curr(rq, p, WF_FORK); #ifdef CONFIG_SMP if (p->sched_class->task_woken) p->sched_class->task_woken(rq, p); #endif task_rq_unlock(rq, &flags); put_cpu(); } #ifdef CONFIG_PREEMPT_NOTIFIERS /** * preempt_notifier_register - tell me when current is 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 /* !CONFIG_PREEMPT_NOTIFIERS */ 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 /* CONFIG_PREEMPT_NOTIFIERS */ /** * 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); #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW local_irq_disable(); #endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */ perf_event_task_sched_in(current); #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW local_irq_enable(); #endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */ 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); } } #ifdef CONFIG_SMP /* assumes rq->lock is held */ static inline void pre_schedule(struct rq *rq, struct task_struct *prev) { if (prev->sched_class->pre_schedule) prev->sched_class->pre_schedule(rq, prev); } /* rq->lock is NOT held, but preemption is disabled */ static inline void post_schedule(struct rq *rq) { if (rq->post_schedule) { unsigned long flags; raw_spin_lock_irqsave(&rq->lock, flags); if (rq->curr->sched_class->post_schedule) rq->curr->sched_class->post_schedule(rq); raw_spin_unlock_irqrestore(&rq->lock, flags); rq->post_schedule = 0; } } #else static inline void pre_schedule(struct rq *rq, struct task_struct *p) { } static inline void post_schedule(struct rq *rq) { } #endif /** * 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); /* * FIXME: do we need to worry about rq being invalidated by the * task_switch? */ post_schedule(rq); #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); trace_sched_switch(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_start_context_switch(prev); if (!mm) { next->active_mm = oldmm; atomic_inc(&oldmm->mm_count); enter_lazy_tlb(oldmm, next); } else switch_mm(oldmm, mm, next); if (!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_iowait_cpu(int cpu) { struct rq *this = cpu_rq(cpu); return atomic_read(&this->nr_iowait); } unsigned long this_cpu_load(void) { struct rq *this = this_rq(); return this->cpu_load[0]; } /* Variables and functions for calc_load */ static atomic_long_t calc_load_tasks; static unsigned long calc_load_update; unsigned long avenrun[3]; EXPORT_SYMBOL(avenrun); static long calc_load_fold_active(struct rq *this_rq) { long nr_active, delta = 0; nr_active = this_rq->nr_running; nr_active += (long) this_rq->nr_uninterruptible; if (nr_active != this_rq->calc_load_active) { delta = nr_active - this_rq->calc_load_active; this_rq->calc_load_active = nr_active; } return delta; } #ifdef CONFIG_NO_HZ /* * For NO_HZ we delay the active fold to the next LOAD_FREQ update. * * When making the ILB scale, we should try to pull this in as well. */ static atomic_long_t calc_load_tasks_idle; static void calc_load_account_idle(struct rq *this_rq) { long delta; delta = calc_load_fold_active(this_rq); if (delta) atomic_long_add(delta, &calc_load_tasks_idle); } static long calc_load_fold_idle(void) { long delta = 0; /* * Its got a race, we don't care... */ if (atomic_long_read(&calc_load_tasks_idle)) delta = atomic_long_xchg(&calc_load_tasks_idle, 0); return delta; } #else static void calc_load_account_idle(struct rq *this_rq) { } static inline long calc_load_fold_idle(void) { return 0; } #endif /** * get_avenrun - get the load average array * @loads: pointer to dest load array * @offset: offset to add * @shift: shift count to shift the result left * * These values are estimates at best, so no need for locking. */ void get_avenrun(unsigned long *loads, unsigned long offset, int shift) { loads[0] = (avenrun[0] + offset) << shift; loads[1] = (avenrun[1] + offset) << shift; loads[2] = (avenrun[2] + offset) << shift; } static unsigned long calc_load(unsigned long load, unsigned long exp, unsigned long active) { load *= exp; load += active * (FIXED_1 - exp); return load >> FSHIFT; } /* * calc_load - update the avenrun load estimates 10 ticks after the * CPUs have updated calc_load_tasks. */ void calc_global_load(void) { unsigned long upd = calc_load_update + 10; long active; if (time_before(jiffies, upd)) return; active = atomic_long_read(&calc_load_tasks); active = active > 0 ? active * FIXED_1 : 0; avenrun[0] = calc_load(avenrun[0], EXP_1, active); avenrun[1] = calc_load(avenrun[1], EXP_5, active); avenrun[2] = calc_load(avenrun[2], EXP_15, active); calc_load_update += LOAD_FREQ; } /* * Called from update_cpu_load() to periodically update this CPU's * active count. */ static void calc_load_account_active(struct rq *this_rq) { long delta; if (time_before(jiffies, this_rq->calc_load_update)) return; delta = calc_load_fold_active(this_rq); delta += calc_load_fold_idle(); if (delta) atomic_long_add(delta, &calc_load_tasks); this_rq->calc_load_update += LOAD_FREQ; } /* * The exact cpuload at various idx values, calculated at every tick would be * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load * * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called * on nth tick when cpu may be busy, then we have: * load = ((2^idx - 1) / 2^idx)^(n-1) * load * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load * * decay_load_missed() below does efficient calculation of * load = ((2^idx - 1) / 2^idx)^(n-1) * load * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load * * The calculation is approximated on a 128 point scale. * degrade_zero_ticks is the number of ticks after which load at any * particular idx is approximated to be zero. * degrade_factor is a precomputed table, a row for each load idx. * Each column corresponds to degradation factor for a power of two ticks, * based on 128 point scale. * Example: * row 2, col 3 (=12) says that the degradation at load idx 2 after * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8). * * With this power of 2 load factors, we can degrade the load n times * by looking at 1 bits in n and doing as many mult/shift instead of * n mult/shifts needed by the exact degradation. */ #define DEGRADE_SHIFT 7 static const unsigned char degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128}; static const unsigned char degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = { {0, 0, 0, 0, 0, 0, 0, 0}, {64, 32, 8, 0, 0, 0, 0, 0}, {96, 72, 40, 12, 1, 0, 0}, {112, 98, 75, 43, 15, 1, 0}, {120, 112, 98, 76, 45, 16, 2} }; /* * Update cpu_load for any missed ticks, due to tickless idle. The backlog * would be when CPU is idle and so we just decay the old load without * adding any new load. */ static unsigned long decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) { int j = 0; if (!missed_updates) return load; if (missed_updates >= degrade_zero_ticks[idx]) return 0; if (idx == 1) return load >> missed_updates; while (missed_updates) { if (missed_updates % 2) load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT; missed_updates >>= 1; j++; } return load; } /* * Update rq->cpu_load[] statistics. This function is usually called every * scheduler tick (TICK_NSEC). With tickless idle this will not be called * every tick. We fix it up based on jiffies. */ static void update_cpu_load(struct rq *this_rq) { unsigned long this_load = this_rq->load.weight; unsigned long curr_jiffies = jiffies; unsigned long pending_updates; int i, scale; this_rq->nr_load_updates++; /* Avoid repeated calls on same jiffy, when moving in and out of idle */ if (curr_jiffies == this_rq->last_load_update_tick) return; pending_updates = curr_jiffies - this_rq->last_load_update_tick; this_rq->last_load_update_tick = curr_jiffies; /* Update our load: */ this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */ for (i = 1, scale = 2; 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]; old_load = decay_load_missed(old_load, pending_updates - 1, 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; } sched_avg_update(this_rq); } static void update_cpu_load_active(struct rq *this_rq) { update_cpu_load(this_rq); calc_load_account_active(this_rq); } #ifdef CONFIG_SMP /* * 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) { struct task_struct *p = current; unsigned long flags; struct rq *rq; int dest_cpu; rq = task_rq_lock(p, &flags); dest_cpu = p->sched_class->select_task_rq(rq, p, SD_BALANCE_EXEC, 0); if (dest_cpu == smp_processor_id()) goto unlock; /* * select_task_rq() can race against ->cpus_allowed */ if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed) && likely(cpu_active(dest_cpu)) && migrate_task(p, dest_cpu)) { struct migration_arg arg = { p, dest_cpu }; task_rq_unlock(rq, &flags); stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); return; } unlock: task_rq_unlock(rq, &flags); } #endif DEFINE_PER_CPU(struct kernel_stat, kstat); EXPORT_PER_CPU_SYMBOL(kstat); /* * Return any ns on the sched_clock that have not yet been accounted in * @p in case that task is currently running. * * Called with task_rq_lock() held on @rq. */ static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq) { u64 ns = 0; if (task_current(rq, p)) { update_rq_clock(rq); ns = rq->clock_task - p->se.exec_start; if ((s64)ns < 0) ns = 0; } return ns; } unsigned long long task_delta_exec(struct task_struct *p) { unsigned long flags; struct rq *rq; u64 ns = 0; rq = task_rq_lock(p, &flags); ns = do_task_delta_exec(p, rq); task_rq_unlock(rq, &flags); return ns; } /* * Return accounted runtime for the task. * In case the task is currently running, return the runtime plus current's * pending runtime that have not been accounted yet. */ unsigned long long task_sched_runtime(struct task_struct *p) { unsigned long flags; struct rq *rq; u64 ns = 0; rq = task_rq_lock(p, &flags); ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq); task_rq_unlock(rq, &flags); return ns; } /* * Return sum_exec_runtime for the thread group. * In case the task is currently running, return the sum plus current's * pending runtime that have not been accounted yet. * * Note that the thread group might have other running tasks as well, * so the return value not includes other pending runtime that other * running tasks might have. */ unsigned long long thread_group_sched_runtime(struct task_struct *p) { struct task_cputime totals; unsigned long flags; struct rq *rq; u64 ns; rq = task_rq_lock(p, &flags); thread_group_cputime(p, &totals); ns = totals.sum_exec_runtime + do_task_delta_exec(p, rq); 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 * @cputime_scaled: cputime scaled by cpu frequency */ void account_user_time(struct task_struct *p, cputime_t cputime, cputime_t cputime_scaled) { struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t tmp; /* Add user time to process. */ p->utime = cputime_add(p->utime, cputime); p->utimescaled = cputime_add(p->utimescaled, cputime_scaled); account_group_user_time(p, 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); cpuacct_update_stats(p, CPUACCT_STAT_USER, cputime); /* Account for user time used */ acct_update_integrals(p); } /* * 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 * @cputime_scaled: cputime scaled by cpu frequency */ static void account_guest_time(struct task_struct *p, cputime_t cputime, cputime_t cputime_scaled) { cputime64_t tmp; struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; tmp = cputime_to_cputime64(cputime); /* Add guest time to process. */ p->utime = cputime_add(p->utime, cputime); p->utimescaled = cputime_add(p->utimescaled, cputime_scaled); account_group_user_time(p, cputime); p->gtime = cputime_add(p->gtime, cputime); /* Add guest time to cpustat. */ if (TASK_NICE(p) > 0) { cpustat->nice = cputime64_add(cpustat->nice, tmp); cpustat->guest_nice = cputime64_add(cpustat->guest_nice, tmp); } else { cpustat->user = cputime64_add(cpustat->user, tmp); cpustat->guest = cputime64_add(cpustat->guest, tmp); } } /* * 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 * @cputime_scaled: cputime scaled by cpu frequency */ void account_system_time(struct task_struct *p, int hardirq_offset, cputime_t cputime, cputime_t cputime_scaled) { struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t tmp; if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) { account_guest_time(p, cputime, cputime_scaled); return; } /* Add system time to process. */ p->stime = cputime_add(p->stime, cputime); p->stimescaled = cputime_add(p->stimescaled, cputime_scaled); account_group_system_time(p, 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 (in_serving_softirq()) cpustat->softirq = cputime64_add(cpustat->softirq, tmp); else cpustat->system = cputime64_add(cpustat->system, tmp); cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime); /* Account for system time used */ acct_update_integrals(p); } /* * Account for involuntary wait time. * @steal: the cpu time spent in involuntary wait */ void account_steal_time(cputime_t cputime) { struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t cputime64 = cputime_to_cputime64(cputime); cpustat->steal = cputime64_add(cpustat->steal, cputime64); } /* * Account for idle time. * @cputime: the cpu time spent in idle wait */ void account_idle_time(cputime_t cputime) { struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t cputime64 = cputime_to_cputime64(cputime); struct rq *rq = this_rq(); if (atomic_read(&rq->nr_iowait) > 0) cpustat->iowait = cputime64_add(cpustat->iowait, cputime64); else cpustat->idle = cputime64_add(cpustat->idle, cputime64); } #ifndef CONFIG_VIRT_CPU_ACCOUNTING /* * Account a single tick of cpu time. * @p: the process that the cpu time gets accounted to * @user_tick: indicates if the tick is a user or a system tick */ void account_process_tick(struct task_struct *p, int user_tick) { cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy); struct rq *rq = this_rq(); if (user_tick) account_user_time(p, cputime_one_jiffy, one_jiffy_scaled); else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET)) account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy, one_jiffy_scaled); else account_idle_time(cputime_one_jiffy); } /* * Account multiple ticks of steal time. * @p: the process from which the cpu time has been stolen * @ticks: number of stolen ticks */ void account_steal_ticks(unsigned long ticks) { account_steal_time(jiffies_to_cputime(ticks)); } /* * Account multiple ticks of idle time. * @ticks: number of stolen ticks */ void account_idle_ticks(unsigned long ticks) { account_idle_time(jiffies_to_cputime(ticks)); } #endif /* * Use precise platform statistics if available: */ #ifdef CONFIG_VIRT_CPU_ACCOUNTING void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st) { *ut = p->utime; *st = p->stime; } void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st) { struct task_cputime cputime; thread_group_cputime(p, &cputime); *ut = cputime.utime; *st = cputime.stime; } #else #ifndef nsecs_to_cputime # define nsecs_to_cputime(__nsecs) nsecs_to_jiffies(__nsecs) #endif void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st) { cputime_t rtime, utime = p->utime, total = cputime_add(utime, p->stime); /* * Use CFS's precise accounting: */ rtime = nsecs_to_cputime(p->se.sum_exec_runtime); if (total) { u64 temp = rtime; temp *= utime; do_div(temp, total); utime = (cputime_t)temp; } else utime = rtime; /* * Compare with previous values, to keep monotonicity: */ p->prev_utime = max(p->prev_utime, utime); p->prev_stime = max(p->prev_stime, cputime_sub(rtime, p->prev_utime)); *ut = p->prev_utime; *st = p->prev_stime; } /* * Must be called with siglock held. */ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st) { struct signal_struct *sig = p->signal; struct task_cputime cputime; cputime_t rtime, utime, total; thread_group_cputime(p, &cputime); total = cputime_add(cputime.utime, cputime.stime); rtime = nsecs_to_cputime(cputime.sum_exec_runtime); if (total) { u64 temp = rtime; temp *= cputime.utime; do_div(temp, total); utime = (cputime_t)temp; } else utime = rtime; sig->prev_utime = max(sig->prev_utime, utime); sig->prev_stime = max(sig->prev_stime, cputime_sub(rtime, sig->prev_utime)); *ut = sig->prev_utime; *st = sig->prev_stime; } #endif /* * 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; sched_clock_tick(); raw_spin_lock(&rq->lock); update_rq_clock(rq); update_cpu_load_active(rq); curr->sched_class->task_tick(rq, curr, 0); raw_spin_unlock(&rq->lock); perf_event_task_tick(); #ifdef CONFIG_SMP rq->idle_at_tick = idle_cpu(cpu); trigger_load_balance(rq, cpu); #endif } notrace unsigned long get_parent_ip(unsigned long addr) { if (in_lock_functions(addr)) { addr = CALLER_ADDR2; if (in_lock_functions(addr)) addr = CALLER_ADDR3; } return addr; } #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ defined(CONFIG_PREEMPT_TRACER)) void __kprobes add_preempt_count(int val) { #ifdef CONFIG_DEBUG_PREEMPT /* * Underflow? */ if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) return; #endif preempt_count() += val; #ifdef CONFIG_DEBUG_PREEMPT /* * Spinlock count overflowing soon? */ DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK - 10); #endif if (preempt_count() == val) trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); } EXPORT_SYMBOL(add_preempt_count); void __kprobes sub_preempt_count(int val) { #ifdef CONFIG_DEBUG_PREEMPT /* * 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; #endif if (preempt_count() == val) trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 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); print_modules(); 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() && !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 } static void put_prev_task(struct rq *rq, struct task_struct *prev) { if (prev->se.on_rq) update_rq_clock(rq); prev->sched_class->put_prev_task(rq, prev); } /* * Pick up the highest-prio task: */ static inline struct task_struct * pick_next_task(struct rq *rq) { 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; } for_each_class(class) { p = class->pick_next_task(rq); if (p) return p; } BUG(); /* the idle class will always have a runnable task */ } /* * schedule() is the main scheduler function. */ asmlinkage void __sched schedule(void) { struct task_struct *prev, *next; unsigned long *switch_count; struct rq *rq; int cpu; need_resched: preempt_disable(); cpu = smp_processor_id(); rq = cpu_rq(cpu); rcu_note_context_switch(cpu); prev = rq->curr; release_kernel_lock(prev); need_resched_nonpreemptible: schedule_debug(prev); if (sched_feat(HRTICK)) hrtick_clear(rq); raw_spin_lock_irq(&rq->lock); switch_count = &prev->nivcsw; if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { if (unlikely(signal_pending_state(prev->state, prev))) { prev->state = TASK_RUNNING; } else { /* * If a worker is going to sleep, notify and * ask workqueue whether it wants to wake up a * task to maintain concurrency. If so, wake * up the task. */ if (prev->flags & PF_WQ_WORKER) { struct task_struct *to_wakeup; to_wakeup = wq_worker_sleeping(prev, cpu); if (to_wakeup) try_to_wake_up_local(to_wakeup); } deactivate_task(rq, prev, DEQUEUE_SLEEP); } switch_count = &prev->nvcsw; } pre_schedule(rq, prev); if (unlikely(!rq->nr_running)) idle_balance(cpu, rq); clear_tsk_need_resched(prev); put_prev_task(rq, prev); next = pick_next_task(rq); if (likely(prev != next)) { sched_info_switch(prev, next); perf_event_task_sched_out(prev, next); rq->nr_switches++; rq->curr = next; ++*switch_count; context_switch(rq, prev, next); /* unlocks the rq */ /* * The context switch have flipped the stack from under us * and restored the local variables which were saved when * this task called schedule() in the past. prev == current * is still correct, but it can be moved to another cpu/rq. */ cpu = smp_processor_id(); rq = cpu_rq(cpu); } else raw_spin_unlock_irq(&rq->lock); post_schedule(rq); if (unlikely(reacquire_kernel_lock(prev))) goto need_resched_nonpreemptible; preempt_enable_no_resched(); if (need_resched()) goto need_resched; } EXPORT_SYMBOL(schedule); #ifdef CONFIG_MUTEX_SPIN_ON_OWNER /* * Look out! "owner" is an entirely speculative pointer * access and not reliable. */ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner) { unsigned int cpu; struct rq *rq; if (!sched_feat(OWNER_SPIN)) return 0; #ifdef CONFIG_DEBUG_PAGEALLOC /* * Need to access the cpu field knowing that * DEBUG_PAGEALLOC could have unmapped it if * the mutex owner just released it and exited. */ if (probe_kernel_address(&owner->cpu, cpu)) return 0; #else cpu = owner->cpu; #endif /* * Even if the access succeeded (likely case), * the cpu field may no longer be valid. */ if (cpu >= nr_cpumask_bits) return 0; /* * We need to validate that we can do a * get_cpu() and that we have the percpu area. */ if (!cpu_online(cpu)) return 0; rq = cpu_rq(cpu); for (;;) { /* * Owner changed, break to re-assess state. */ if (lock->owner != owner) { /* * If the lock has switched to a different owner, * we likely have heavy contention. Return 0 to quit * optimistic spinning and not contend further: */ if (lock->owner) return 0; break; } /* * Is that owner really running on that cpu? */ if (task_thread_info(rq->curr) != owner || need_resched()) return 0; cpu_relax(); } return 1; } #endif #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 notrace preempt_schedule(void) { struct thread_info *ti = current_thread_info(); /* * 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_notrace(PREEMPT_ACTIVE); schedule(); sub_preempt_count_notrace(PREEMPT_ACTIVE); /* * Check again in case we missed a preemption opportunity * between schedule and now. */ barrier(); } while (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(); /* Catch callers which need to be fixed */ BUG_ON(ti->preempt_count || !irqs_disabled()); do { add_preempt_count(PREEMPT_ACTIVE); local_irq_enable(); schedule(); local_irq_disable(); sub_preempt_count(PREEMPT_ACTIVE); /* * Check again in case we missed a preemption opportunity * between schedule and now. */ barrier(); } while (need_resched()); } #endif /* CONFIG_PREEMPT */ int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags, void *key) { return try_to_wake_up(curr->private, mode, wake_flags); } 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 wake_flags, 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, wake_flags, 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 * * It may be assumed that this function implies a write memory barrier before * changing the task state if and only if any tasks are woken up. */ void __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 __wake_up_locked(wait_queue_head_t *q, unsigned int mode) { __wake_up_common(q, mode, 1, 0, NULL); } EXPORT_SYMBOL_GPL(__wake_up_locked); void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key) { __wake_up_common(q, mode, 1, 0, key); } /** * __wake_up_sync_key - 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: opaque value to be passed to wakeup targets * * 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. * * It may be assumed that this function implies a write memory barrier before * changing the task state if and only if any tasks are woken up. */ void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr_exclusive, void *key) { unsigned long flags; int wake_flags = WF_SYNC; if (unlikely(!q)) return; if (unlikely(!nr_exclusive)) wake_flags = 0; spin_lock_irqsave(&q->lock, flags); __wake_up_common(q, mode, nr_exclusive, wake_flags, key); spin_unlock_irqrestore(&q->lock, flags); } EXPORT_SYMBOL_GPL(__wake_up_sync_key); /* * __wake_up_sync - see __wake_up_sync_key() */ void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive) { __wake_up_sync_key(q, mode, nr_exclusive, NULL); } EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */ /** * complete: - signals a single thread waiting on this completion * @x: holds the state of this particular completion * * This will wake up a single thread waiting on this completion. Threads will be * awakened in the same order in which they were queued. * * See also complete_all(), wait_for_completion() and related routines. * * It may be assumed that this function implies a write memory barrier before * changing the task state if and only if any tasks are woken up. */ void complete(struct completion *x) { unsigned long flags; spin_lock_irqsave(&x->wait.lock, flags); x->done++; __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL); spin_unlock_irqrestore(&x->wait.lock, flags); } EXPORT_SYMBOL(complete); /** * complete_all: - signals all threads waiting on this completion * @x: holds the state of this particular completion * * This will wake up all threads waiting on this particular completion event. * * It may be assumed that this function implies a write memory barrier before * changing the task state if and only if any tasks are woken up. */ 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_NORMAL, 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); __add_wait_queue_tail_exclusive(&x->wait, &wait); do { if (signal_pending_state(state, current)) { timeout = -ERESTARTSYS; break; } __set_current_state(state); spin_unlock_irq(&x->wait.lock); timeout = schedule_timeout(timeout); spin_lock_irq(&x->wait.lock); } while (!x->done && timeout); __remove_wait_queue(&x->wait, &wait); if (!x->done) return timeout; } x->done--; return timeout ?: 1; } 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; } /** * wait_for_completion: - waits for completion of a task * @x: holds the state of this particular completion * * This waits to be signaled for completion of a specific task. It is NOT * interruptible and there is no timeout. * * See also similar routines (i.e. wait_for_completion_timeout()) with timeout * and interrupt capability. Also see complete(). */ void __sched wait_for_completion(struct completion *x) { wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); } EXPORT_SYMBOL(wait_for_completion); /** * wait_for_completion_timeout: - waits for completion of a task (w/timeout) * @x: holds the state of this particular completion * @timeout: timeout value in jiffies * * This waits for either a completion of a specific task to be signaled or for a * specified timeout to expire. The timeout is in jiffies. It is not * interruptible. */ 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); /** * wait_for_completion_interruptible: - waits for completion of a task (w/intr) * @x: holds the state of this particular completion * * This waits for completion of a specific task to be signaled. It is * interruptible. */ 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); /** * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr)) * @x: holds the state of this particular completion * @timeout: timeout value in jiffies * * This waits for either a completion of a specific task to be signaled or for a * specified timeout to expire. It is interruptible. The timeout is in jiffies. */ 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); /** * wait_for_completion_killable: - waits for completion of a task (killable) * @x: holds the state of this particular completion * * This waits to be signaled for completion of a specific task. It can be * interrupted by a kill signal. */ int __sched wait_for_completion_killable(struct completion *x) { long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE); if (t == -ERESTARTSYS) return t; return 0; } EXPORT_SYMBOL(wait_for_completion_killable); /** * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable)) * @x: holds the state of this particular completion * @timeout: timeout value in jiffies * * This waits for either a completion of a specific task to be * signaled or for a specified timeout to expire. It can be * interrupted by a kill signal. The timeout is in jiffies. */ unsigned long __sched wait_for_completion_killable_timeout(struct completion *x, unsigned long timeout) { return wait_for_common(x, timeout, TASK_KILLABLE); } EXPORT_SYMBOL(wait_for_completion_killable_timeout); /** * try_wait_for_completion - try to decrement a completion without blocking * @x: completion structure * * Returns: 0 if a decrement cannot be done without blocking * 1 if a decrement succeeded. * * If a completion is being used as a counting completion, * attempt to decrement the counter without blocking. This * enables us to avoid waiting if the resource the completion * is protecting is not available. */ bool try_wait_for_completion(struct completion *x) { unsigned long flags; int ret = 1; spin_lock_irqsave(&x->wait.lock, flags); if (!x->done) ret = 0; else x->done--; spin_unlock_irqrestore(&x->wait.lock, flags); return ret; } EXPORT_SYMBOL(try_wait_for_completion); /** * completion_done - Test to see if a completion has any waiters * @x: completion structure * * Returns: 0 if there are waiters (wait_for_completion() in progress) * 1 if there are no waiters. * */ bool completion_done(struct completion *x) { unsigned long flags; int ret = 1; spin_lock_irqsave(&x->wait.lock, flags); if (!x->done) ret = 0; spin_unlock_irqrestore(&x->wait.lock, flags); return ret; } EXPORT_SYMBOL(completion_done); 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; const struct sched_class *prev_class; BUG_ON(prio < 0 || prio > MAX_PRIO); rq = task_rq_lock(p, &flags); trace_sched_pi_setprio(p, prio); oldprio = p->prio; prev_class = p->sched_class; on_rq = p->se.on_rq; running = task_current(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 (running) p->sched_class->set_curr_task(rq); if (on_rq) { enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0); check_class_changed(rq, p, prev_class, oldprio, running); } 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); /* * 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); 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); /* * 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 <= task_rlimit(p, RLIMIT_NICE) || 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. */ SYSCALL_DEFINE1(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 = TASK_NICE(current) + 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(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; p->rt_priority = prio; p->normal_prio = normal_prio(p); /* we are holding p->pi_lock already */ p->prio = rt_mutex_getprio(p); if (rt_prio(p->prio)) p->sched_class = &rt_sched_class; else p->sched_class = &fair_sched_class; set_load_weight(p); } /* * check the target process has a UID that matches the current process's */ static bool check_same_owner(struct task_struct *p) { const struct cred *cred = current_cred(), *pcred; bool match; rcu_read_lock(); pcred = __task_cred(p); match = (cred->euid == pcred->euid || cred->euid == pcred->uid); rcu_read_unlock(); return match; } static int __sched_setscheduler(struct task_struct *p, int policy, struct sched_param *param, bool user) { int retval, oldprio, oldpolicy = -1, on_rq, running; unsigned long flags; const struct sched_class *prev_class; struct rq *rq; int reset_on_fork; /* may grab non-irq protected spin_locks */ BUG_ON(in_interrupt()); recheck: /* double check policy once rq lock held */ if (policy < 0) { reset_on_fork = p->sched_reset_on_fork; policy = oldpolicy = p->policy; } else { reset_on_fork = !!(policy & SCHED_RESET_ON_FORK); policy &= ~SCHED_RESET_ON_FORK; 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 (user && !capable(CAP_SYS_NICE)) { if (rt_policy(policy)) { unsigned long rlim_rtprio = task_rlimit(p, RLIMIT_RTPRIO); /* 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 (!check_same_owner(p)) return -EPERM; /* Normal users shall not reset the sched_reset_on_fork flag */ if (p->sched_reset_on_fork && !reset_on_fork) return -EPERM; } if (user) { retval = security_task_setscheduler(p); if (retval) return retval; } /* * make sure no PI-waiters arrive (or leave) while we are * changing the priority of the task: */ raw_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); /* * Changing the policy of the stop threads its a very bad idea */ if (p == rq->stop) { __task_rq_unlock(rq); raw_spin_unlock_irqrestore(&p->pi_lock, flags); return -EINVAL; } #ifdef CONFIG_RT_GROUP_SCHED if (user) { /* * Do not allow realtime tasks into groups that have no runtime * assigned. */ if (rt_bandwidth_enabled() && rt_policy(policy) && task_group(p)->rt_bandwidth.rt_runtime == 0) { __task_rq_unlock(rq); raw_spin_unlock_irqrestore(&p->pi_lock, flags); return -EPERM; } } #endif /* recheck policy now with rq lock held */ if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { policy = oldpolicy = -1; __task_rq_unlock(rq); raw_spin_unlock_irqrestore(&p->pi_lock, flags); goto recheck; } on_rq = p->se.on_rq; running = task_current(rq, p); if (on_rq) deactivate_task(rq, p, 0); if (running) p->sched_class->put_prev_task(rq, p); p->sched_reset_on_fork = reset_on_fork; oldprio = p->prio; prev_class = p->sched_class; __setscheduler(rq, p, policy, param->sched_priority); if (running) p->sched_class->set_curr_task(rq); if (on_rq) { activate_task(rq, p, 0); check_class_changed(rq, p, prev_class, oldprio, running); } __task_rq_unlock(rq); raw_spin_unlock_irqrestore(&p->pi_lock, flags); rt_mutex_adjust_pi(p); return 0; } /** * 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) { return __sched_setscheduler(p, policy, param, true); } EXPORT_SYMBOL_GPL(sched_setscheduler); /** * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. * @p: the task in question. * @policy: new policy. * @param: structure containing the new RT priority. * * Just like sched_setscheduler, only don't bother checking if the * current context has permission. For example, this is needed in * stop_machine(): we create temporary high priority worker threads, * but our caller might not have that capability. */ int sched_setscheduler_nocheck(struct task_struct *p, int policy, struct sched_param *param) { return __sched_setscheduler(p, policy, param, false); } 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. */ SYSCALL_DEFINE3(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. */ SYSCALL_DEFINE2(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. */ SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) { struct task_struct *p; int retval; if (pid < 0) return -EINVAL; retval = -ESRCH; rcu_read_lock(); p = find_process_by_pid(pid); if (p) { retval = security_task_getscheduler(p); if (!retval) retval = p->policy | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); } rcu_read_unlock(); return retval; } /** * sys_sched_getparam - get the RT priority of a thread * @pid: the pid in question. * @param: structure containing the RT priority. */ SYSCALL_DEFINE2(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; rcu_read_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; rcu_read_unlock(); /* * 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: rcu_read_unlock(); return retval; } long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) { cpumask_var_t cpus_allowed, new_mask; struct task_struct *p; int retval; get_online_cpus(); rcu_read_lock(); p = find_process_by_pid(pid); if (!p) { rcu_read_unlock(); put_online_cpus(); return -ESRCH; } /* Prevent p going away */ get_task_struct(p); rcu_read_unlock(); if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { retval = -ENOMEM; goto out_put_task; } if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { retval = -ENOMEM; goto out_free_cpus_allowed; } retval = -EPERM; if (!check_same_owner(p) && !capable(CAP_SYS_NICE)) goto out_unlock; retval = security_task_setscheduler(p); if (retval) goto out_unlock; cpuset_cpus_allowed(p, cpus_allowed); cpumask_and(new_mask, in_mask, cpus_allowed); again: retval = set_cpus_allowed_ptr(p, new_mask); if (!retval) { cpuset_cpus_allowed(p, cpus_allowed); if (!cpumask_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 */ cpumask_copy(new_mask, cpus_allowed); goto again; } } out_unlock: free_cpumask_var(new_mask); out_free_cpus_allowed: free_cpumask_var(cpus_allowed); out_put_task: put_task_struct(p); put_online_cpus(); return retval; } static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, struct cpumask *new_mask) { if (len < cpumask_size()) cpumask_clear(new_mask); else if (len > cpumask_size()) len = cpumask_size(); 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 */ SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, unsigned long __user *, user_mask_ptr) { cpumask_var_t new_mask; int retval; if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) return -ENOMEM; retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); if (retval == 0) retval = sched_setaffinity(pid, new_mask); free_cpumask_var(new_mask); return retval; } long sched_getaffinity(pid_t pid, struct cpumask *mask) { struct task_struct *p; unsigned long flags; struct rq *rq; int retval; get_online_cpus(); rcu_read_lock(); retval = -ESRCH; p = find_process_by_pid(pid); if (!p) goto out_unlock; retval = security_task_getscheduler(p); if (retval) goto out_unlock; rq = task_rq_lock(p, &flags); cpumask_and(mask, &p->cpus_allowed, cpu_online_mask); task_rq_unlock(rq, &flags); out_unlock: rcu_read_unlock(); put_online_cpus(); 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 */ SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, unsigned long __user *, user_mask_ptr) { int ret; cpumask_var_t mask; if ((len * BITS_PER_BYTE) < nr_cpu_ids) return -EINVAL; if (len & (sizeof(unsigned long)-1)) return -EINVAL; if (!alloc_cpumask_var(&mask, GFP_KERNEL)) return -ENOMEM; ret = sched_getaffinity(pid, mask); if (ret == 0) { size_t retlen = min_t(size_t, len, cpumask_size()); if (copy_to_user(user_mask_ptr, mask, retlen)) ret = -EFAULT; else ret = retlen; } free_cpumask_var(mask); return ret; } /** * 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. */ SYSCALL_DEFINE0(sched_yield) { 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_); do_raw_spin_unlock(&rq->lock); preempt_enable_no_resched(); schedule(); return 0; } static inline int should_resched(void) { return need_resched() && !(preempt_count() & PREEMPT_ACTIVE); } static void __cond_resched(void) { add_preempt_count(PREEMPT_ACTIVE); schedule(); sub_preempt_count(PREEMPT_ACTIVE); } int __sched _cond_resched(void) { if (should_resched()) { __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 resched = should_resched(); int ret = 0; lockdep_assert_held(lock); if (spin_needbreak(lock) || resched) { spin_unlock(lock); if (resched) __cond_resched(); else cpu_relax(); ret = 1; spin_lock(lock); } return ret; } EXPORT_SYMBOL(__cond_resched_lock); int __sched __cond_resched_softirq(void) { BUG_ON(!in_softirq()); if (should_resched()) { 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. */ void __sched io_schedule(void) { struct rq *rq = raw_rq(); delayacct_blkio_start(); atomic_inc(&rq->nr_iowait); current->in_iowait = 1; schedule(); current->in_iowait = 0; atomic_dec(&rq->nr_iowait); delayacct_blkio_end(); } EXPORT_SYMBOL(io_schedule); long __sched io_schedule_timeout(long timeout) { struct rq *rq = raw_rq(); long ret; delayacct_blkio_start(); atomic_inc(&rq->nr_iowait); current->in_iowait = 1; ret = schedule_timeout(timeout); current->in_iowait = 0; 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. */ SYSCALL_DEFINE1(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. */ SYSCALL_DEFINE1(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. */ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, struct timespec __user *, interval) { struct task_struct *p; unsigned int time_slice; unsigned long flags; struct rq *rq; int retval; struct timespec t; if (pid < 0) return -EINVAL; retval = -ESRCH; rcu_read_lock(); p = find_process_by_pid(pid); if (!p) goto out_unlock; retval = security_task_getscheduler(p); if (retval) goto out_unlock; rq = task_rq_lock(p, &flags); time_slice = p->sched_class->get_rr_interval(rq, p); task_rq_unlock(rq, &flags); rcu_read_unlock(); jiffies_to_timespec(time_slice, &t); retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; return retval; out_unlock: rcu_read_unlock(); return retval; } static const char stat_nam[] = TASK_STATE_TO_CHAR_STR; void sched_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 free = stack_not_used(p); #endif printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, task_pid_nr(p), task_pid_nr(p->real_parent), (unsigned long)task_thread_info(p)->flags); 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)) sched_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) 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; raw_spin_lock_irqsave(&rq->lock, flags); __sched_fork(idle); idle->state = TASK_RUNNING; idle->se.exec_start = sched_clock(); cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu)); /* * We're having a chicken and egg problem, even though we are * holding rq->lock, the cpu isn't yet set to this cpu so the * lockdep check in task_group() will fail. * * Similar case to sched_fork(). / Alternatively we could * use task_rq_lock() here and obtain the other rq->lock. * * Silence PROVE_RCU */ rcu_read_lock(); __set_task_cpu(idle, cpu); rcu_read_unlock(); rq->curr = rq->idle = idle; #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) idle->oncpu = 1; #endif raw_spin_unlock_irqrestore(&rq->lock, flags); /* Set the preempt count _outside_ the spinlocks! */ #if defined(CONFIG_PREEMPT) 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; ftrace_graph_init_task(idle); } /* * 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_BITS_NONE. */ cpumask_var_t nohz_cpu_mask; /* * 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 int get_update_sysctl_factor(void) { unsigned int cpus = min_t(int, num_online_cpus(), 8); unsigned int factor; switch (sysctl_sched_tunable_scaling) { case SCHED_TUNABLESCALING_NONE: factor = 1; break; case SCHED_TUNABLESCALING_LINEAR: factor = cpus; break; case SCHED_TUNABLESCALING_LOG: default: factor = 1 + ilog2(cpus); break; } return factor; } static void update_sysctl(void) { unsigned int factor = get_update_sysctl_factor(); #define SET_SYSCTL(name) \ (sysctl_##name = (factor) * normalized_sysctl_##name) SET_SYSCTL(sched_min_granularity); SET_SYSCTL(sched_latency); SET_SYSCTL(sched_wakeup_granularity); SET_SYSCTL(sched_shares_ratelimit); #undef SET_SYSCTL } static inline void sched_init_granularity(void) { update_sysctl(); } #ifdef CONFIG_SMP /* * This is how migration works: * * 1) we invoke migration_cpu_stop() on the target CPU using * stop_one_cpu(). * 2) stopper starts to run (implicitly forcing the migrated thread * off the CPU) * 3) it checks whether the migrated task is still in the wrong runqueue. * 4) if it's in the wrong runqueue then the migration thread removes * it and puts it into the right queue. * 5) stopper completes and stop_one_cpu() returns 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_ptr(struct task_struct *p, const struct cpumask *new_mask) { unsigned long flags; struct rq *rq; unsigned int dest_cpu; int ret = 0; /* * Serialize against TASK_WAKING so that ttwu() and wunt() can * drop the rq->lock and still rely on ->cpus_allowed. */ again: while (task_is_waking(p)) cpu_relax(); rq = task_rq_lock(p, &flags); if (task_is_waking(p)) { task_rq_unlock(rq, &flags); goto again; } if (!cpumask_intersects(new_mask, cpu_active_mask)) { ret = -EINVAL; goto out; } if (unlikely((p->flags & PF_THREAD_BOUND) && p != current && !cpumask_equal(&p->cpus_allowed, new_mask))) { ret = -EINVAL; goto out; } if (p->sched_class->set_cpus_allowed) p->sched_class->set_cpus_allowed(p, new_mask); else { cpumask_copy(&p->cpus_allowed, new_mask); p->rt.nr_cpus_allowed = cpumask_weight(new_mask); } /* Can the task run on the task's current CPU? If so, we're done */ if (cpumask_test_cpu(task_cpu(p), new_mask)) goto out; dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); if (migrate_task(p, dest_cpu)) { struct migration_arg arg = { p, dest_cpu }; /* Need help from migration thread: drop lock and wait. */ task_rq_unlock(rq, &flags); stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); tlb_migrate_finish(p->mm); return 0; } out: task_rq_unlock(rq, &flags); return ret; } EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); /* * 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; if (unlikely(!cpu_active(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 done; /* Affinity changed (again). */ if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)) goto fail; /* * If we're not on a rq, the next wake-up will ensure we're * placed properly. */ if (p->se.on_rq) { deactivate_task(rq_src, p, 0); set_task_cpu(p, dest_cpu); activate_task(rq_dest, p, 0); check_preempt_curr(rq_dest, p, 0); } done: ret = 1; fail: double_rq_unlock(rq_src, rq_dest); return ret; } /* * migration_cpu_stop - this will be executed by a highprio stopper thread * and performs thread migration by bumping thread off CPU then * 'pushing' onto another runqueue. */ static int migration_cpu_stop(void *data) { struct migration_arg *arg = data; /* * The original target cpu might have gone down and we might * be on another cpu but it doesn't matter. */ local_irq_disable(); __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu); local_irq_enable(); return 0; } #ifdef CONFIG_HOTPLUG_CPU /* * Figure out where task on dead CPU should go, use force if necessary. */ void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p) { struct rq *rq = cpu_rq(dead_cpu); int needs_cpu, uninitialized_var(dest_cpu); unsigned long flags; local_irq_save(flags); raw_spin_lock(&rq->lock); needs_cpu = (task_cpu(p) == dead_cpu) && (p->state != TASK_WAKING); if (needs_cpu) dest_cpu = select_fallback_rq(dead_cpu, p); raw_spin_unlock(&rq->lock); /* * It can only fail if we race with set_cpus_allowed(), * in the racer should migrate the task anyway. */ if (needs_cpu) __migrate_task(p, dead_cpu, dest_cpu); local_irq_restore(flags); } /* * 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(cpumask_any(cpu_active_mask)); 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. */ raw_spin_lock_irqsave(&rq->lock, flags); __setscheduler(rq, p, SCHED_FIFO, MAX_RT_PRIO-1); activate_task(rq, p, 0); raw_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. */ raw_spin_unlock_irq(&rq->lock); move_task_off_dead_cpu(dead_cpu, p); raw_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; next = pick_next_task(rq); if (!next) break; next->sched_class->put_prev_task(rq, next); migrate_dead(dead_cpu, next); } } /* * remove the tasks which were accounted by rq from calc_load_tasks. */ static void calc_global_load_remove(struct rq *rq) { atomic_long_sub(rq->calc_load_active, &calc_load_tasks); rq->calc_load_active = 0; } #endif /* CONFIG_HOTPLUG_CPU */ #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) static struct ctl_table sd_ctl_dir[] = { { .procname = "sched_domain", .mode = 0555, }, {} }; static struct ctl_table sd_ctl_root[] = { { .procname = "kernel", .mode = 0555, .child = sd_ctl_dir, }, {} }; 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(13); 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); set_table_entry(&table[11], "name", sd->name, CORENAME_MAX_SIZE, 0444, proc_dostring); /* &table[12] 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_possible_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_possible_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 static void set_rq_online(struct rq *rq) { if (!rq->online) { const struct sched_class *class; cpumask_set_cpu(rq->cpu, rq->rd->online); rq->online = 1; for_each_class(class) { if (class->rq_online) class->rq_online(rq); } } } static void set_rq_offline(struct rq *rq) { if (rq->online) { const struct sched_class *class; for_each_class(class) { if (class->rq_offline) class->rq_offline(rq); } cpumask_clear_cpu(rq->cpu, rq->rd->online); rq->online = 0; } } /* * 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) { int cpu = (long)hcpu; unsigned long flags; struct rq *rq = cpu_rq(cpu); switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: rq->calc_load_update = calc_load_update; break; case CPU_ONLINE: case CPU_ONLINE_FROZEN: /* Update our root-domain */ raw_spin_lock_irqsave(&rq->lock, flags); if (rq->rd) { BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); set_rq_online(rq); } raw_spin_unlock_irqrestore(&rq->lock, flags); break; #ifdef CONFIG_HOTPLUG_CPU case CPU_DEAD: case CPU_DEAD_FROZEN: migrate_live_tasks(cpu); /* Idle task back to normal (off runqueue, low prio) */ raw_spin_lock_irq(&rq->lock); deactivate_task(rq, rq->idle, 0); __setscheduler(rq, rq->idle, SCHED_NORMAL, 0); rq->idle->sched_class = &idle_sched_class; migrate_dead_tasks(cpu); raw_spin_unlock_irq(&rq->lock); migrate_nr_uninterruptible(rq); BUG_ON(rq->nr_running != 0); calc_global_load_remove(rq); break; case CPU_DYING: case CPU_DYING_FROZEN: /* Update our root-domain */ raw_spin_lock_irqsave(&rq->lock, flags); if (rq->rd) { BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); set_rq_offline(rq); } raw_spin_unlock_irqrestore(&rq->lock, flags); break; #endif } return NOTIFY_OK; } /* * Register at high priority so that task migration (migrate_all_tasks) * happens before everything else. This has to be lower priority than * the notifier in the perf_event subsystem, though. */ static struct notifier_block __cpuinitdata migration_notifier = { .notifier_call = migration_call, .priority = CPU_PRI_MIGRATION, }; static int __cpuinit sched_cpu_active(struct notifier_block *nfb, unsigned long action, void *hcpu) { switch (action & ~CPU_TASKS_FROZEN) { case CPU_ONLINE: case CPU_DOWN_FAILED: set_cpu_active((long)hcpu, true); return NOTIFY_OK; default: return NOTIFY_DONE; } } static int __cpuinit sched_cpu_inactive(struct notifier_block *nfb, unsigned long action, void *hcpu) { switch (action & ~CPU_TASKS_FROZEN) { case CPU_DOWN_PREPARE: set_cpu_active((long)hcpu, false); return NOTIFY_OK; default: return NOTIFY_DONE; } } static int __init migration_init(void) { void *cpu = (void *)(long)smp_processor_id(); int err; /* Initialize migration 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); /* Register cpu active notifiers */ cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE); cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE); return 0; } early_initcall(migration_init); #endif #ifdef CONFIG_SMP #ifdef CONFIG_SCHED_DEBUG static __read_mostly int sched_domain_debug_enabled; static int __init sched_domain_debug_setup(char *str) { sched_domain_debug_enabled = 1; return 0; } early_param("sched_debug", sched_domain_debug_setup); static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, struct cpumask *groupmask) { struct sched_group *group = sd->groups; char str[256]; cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd)); cpumask_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 level %s\n", str, sd->name); if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { printk(KERN_ERR "ERROR: domain->span does not contain " "CPU%d\n", cpu); } if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) { 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 (!cpumask_weight(sched_group_cpus(group))) { printk(KERN_CONT "\n"); printk(KERN_ERR "ERROR: empty group\n"); break; } if (cpumask_intersects(groupmask, sched_group_cpus(group))) { printk(KERN_CONT "\n"); printk(KERN_ERR "ERROR: repeated CPUs\n"); break; } cpumask_or(groupmask, groupmask, sched_group_cpus(group)); cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group)); printk(KERN_CONT " %s", str); if (group->cpu_power != SCHED_LOAD_SCALE) { printk(KERN_CONT " (cpu_power = %d)", group->cpu_power); } group = group->next; } while (group != sd->groups); printk(KERN_CONT "\n"); if (!cpumask_equal(sched_domain_span(sd), groupmask)) printk(KERN_ERR "ERROR: groups don't span domain->span\n"); if (sd->parent && !cpumask_subset(groupmask, sched_domain_span(sd->parent))) 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) { cpumask_var_t groupmask; int level = 0; if (!sched_domain_debug_enabled) return; if (!sd) { printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); return; } printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); if (!alloc_cpumask_var(&groupmask, GFP_KERNEL)) { printk(KERN_DEBUG "Cannot load-balance (out of memory)\n"); return; } for (;;) { if (sched_domain_debug_one(sd, cpu, level, groupmask)) break; level++; sd = sd->parent; if (!sd) break; } free_cpumask_var(groupmask); } #else /* !CONFIG_SCHED_DEBUG */ # define sched_domain_debug(sd, cpu) do { } while (0) #endif /* CONFIG_SCHED_DEBUG */ static int sd_degenerate(struct sched_domain *sd) { if (cpumask_weight(sched_domain_span(sd)) == 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_AFFINE)) 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 (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) return 0; /* 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 (nr_node_ids == 1) pflags &= ~SD_SERIALIZE; } if (~cflags & pflags) return 0; return 1; } static void free_rootdomain(struct root_domain *rd) { synchronize_sched(); cpupri_cleanup(&rd->cpupri); free_cpumask_var(rd->rto_mask); free_cpumask_var(rd->online); free_cpumask_var(rd->span); kfree(rd); } static void rq_attach_root(struct rq *rq, struct root_domain *rd) { struct root_domain *old_rd = NULL; unsigned long flags; raw_spin_lock_irqsave(&rq->lock, flags); if (rq->rd) { old_rd = rq->rd; if (cpumask_test_cpu(rq->cpu, old_rd->online)) set_rq_offline(rq); cpumask_clear_cpu(rq->cpu, old_rd->span); /* * If we dont want to free the old_rt yet then * set old_rd to NULL to skip the freeing later * in this function: */ if (!atomic_dec_and_test(&old_rd->refcount)) old_rd = NULL; } atomic_inc(&rd->refcount); rq->rd = rd; cpumask_set_cpu(rq->cpu, rd->span); if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) set_rq_online(rq); raw_spin_unlock_irqrestore(&rq->lock, flags); if (old_rd) free_rootdomain(old_rd); } static int init_rootdomain(struct root_domain *rd) { memset(rd, 0, sizeof(*rd)); if (!alloc_cpumask_var(&rd->span, GFP_KERNEL)) goto out; if (!alloc_cpumask_var(&rd->online, GFP_KERNEL)) goto free_span; if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) goto free_online; if (cpupri_init(&rd->cpupri) != 0) goto free_rto_mask; return 0; free_rto_mask: free_cpumask_var(rd->rto_mask); free_online: free_cpumask_var(rd->online); free_span: free_cpumask_var(rd->span); out: return -ENOMEM; } static void init_defrootdomain(void) { init_rootdomain(&def_root_domain); atomic_set(&def_root_domain.refcount, 1); } static struct root_domain *alloc_rootdomain(void) { struct root_domain *rd; rd = kmalloc(sizeof(*rd), GFP_KERNEL); if (!rd) return NULL; if (init_rootdomain(rd) != 0) { kfree(rd); return NULL; } return rd; } /* * 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, struct root_domain *rd, int cpu) { struct rq *rq = cpu_rq(cpu); struct sched_domain *tmp; for (tmp = sd; tmp; tmp = tmp->parent) tmp->span_weight = cpumask_weight(sched_domain_span(tmp)); /* Remove the sched domains which do not contribute to scheduling. */ for (tmp = sd; tmp; ) { 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; } else tmp = tmp->parent; } if (sd && sd_degenerate(sd)) { sd = sd->parent; if (sd) sd->child = NULL; } sched_domain_debug(sd, cpu); rq_attach_root(rq, rd); rcu_assign_pointer(rq->sd, sd); } /* cpus with isolated domains */ static cpumask_var_t cpu_isolated_map; /* Setup the mask of cpus configured for isolated domains */ static int __init isolated_cpu_setup(char *str) { alloc_bootmem_cpumask_var(&cpu_isolated_map); cpulist_parse(str, 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_cpu_ids * (due to the fact that we keep track of groups covered with a struct cpumask). * * 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(const struct cpumask *span, const struct cpumask *cpu_map, int (*group_fn)(int cpu, const struct cpumask *cpu_map, struct sched_group **sg, struct cpumask *tmpmask), struct cpumask *covered, struct cpumask *tmpmask) { struct sched_group *first = NULL, *last = NULL; int i; cpumask_clear(covered); for_each_cpu(i, span) { struct sched_group *sg; int group = group_fn(i, cpu_map, &sg, tmpmask); int j; if (cpumask_test_cpu(i, covered)) continue; cpumask_clear(sched_group_cpus(sg)); sg->cpu_power = 0; for_each_cpu(j, span) { if (group_fn(j, cpu_map, NULL, tmpmask) != group) continue; cpumask_set_cpu(j, covered); cpumask_set_cpu(j, sched_group_cpus(sg)); } 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, nodemask_t *used_nodes) { int i, n, val, min_val, best_node = 0; min_val = INT_MAX; for (i = 0; i < nr_node_ids; i++) { /* Start at @node */ n = (node + i) % nr_node_ids; if (!nr_cpus_node(n)) continue; /* Skip already used nodes */ if (node_isset(n, *used_nodes)) continue; /* Simple min distance search */ val = node_distance(node, n); if (val < min_val) { min_val = val; best_node = n; } } node_set(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 * @span: resulting cpumask * * 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 void sched_domain_node_span(int node, struct cpumask *span) { nodemask_t used_nodes; int i; cpumask_clear(span); nodes_clear(used_nodes); cpumask_or(span, span, cpumask_of_node(node)); node_set(node, used_nodes); for (i = 1; i < SD_NODES_PER_DOMAIN; i++) { int next_node = find_next_best_node(node, &used_nodes); cpumask_or(span, span, cpumask_of_node(next_node)); } } #endif /* CONFIG_NUMA */ int sched_smt_power_savings = 0, sched_mc_power_savings = 0; /* * The cpus mask in sched_group and sched_domain hangs off the end. * * ( See the the comments in include/linux/sched.h:struct sched_group * and struct sched_domain. ) */ struct static_sched_group { struct sched_group sg; DECLARE_BITMAP(cpus, CONFIG_NR_CPUS); }; struct static_sched_domain { struct sched_domain sd; DECLARE_BITMAP(span, CONFIG_NR_CPUS); }; struct s_data { #ifdef CONFIG_NUMA int sd_allnodes; cpumask_var_t domainspan; cpumask_var_t covered; cpumask_var_t notcovered; #endif cpumask_var_t nodemask; cpumask_var_t this_sibling_map; cpumask_var_t this_core_map; cpumask_var_t this_book_map; cpumask_var_t send_covered; cpumask_var_t tmpmask; struct sched_group **sched_group_nodes; struct root_domain *rd; }; enum s_alloc { sa_sched_groups = 0, sa_rootdomain, sa_tmpmask, sa_send_covered, sa_this_book_map, sa_this_core_map, sa_this_sibling_map, sa_nodemask, sa_sched_group_nodes, #ifdef CONFIG_NUMA sa_notcovered, sa_covered, sa_domainspan, #endif sa_none, }; /* * SMT sched-domains: */ #ifdef CONFIG_SCHED_SMT static DEFINE_PER_CPU(struct static_sched_domain, cpu_domains); static DEFINE_PER_CPU(struct static_sched_group, sched_groups); static int cpu_to_cpu_group(int cpu, const struct cpumask *cpu_map, struct sched_group **sg, struct cpumask *unused) { if (sg) *sg = &per_cpu(sched_groups, cpu).sg; return cpu; } #endif /* CONFIG_SCHED_SMT */ /* * multi-core sched-domains: */ #ifdef CONFIG_SCHED_MC static DEFINE_PER_CPU(struct static_sched_domain, core_domains); static DEFINE_PER_CPU(struct static_sched_group, sched_group_core); static int cpu_to_core_group(int cpu, const struct cpumask *cpu_map, struct sched_group **sg, struct cpumask *mask) { int group; #ifdef CONFIG_SCHED_SMT cpumask_and(mask, topology_thread_cpumask(cpu), cpu_map); group = cpumask_first(mask); #else group = cpu; #endif if (sg) *sg = &per_cpu(sched_group_core, group).sg; return group; } #endif /* CONFIG_SCHED_MC */ /* * book sched-domains: */ #ifdef CONFIG_SCHED_BOOK static DEFINE_PER_CPU(struct static_sched_domain, book_domains); static DEFINE_PER_CPU(struct static_sched_group, sched_group_book); static int cpu_to_book_group(int cpu, const struct cpumask *cpu_map, struct sched_group **sg, struct cpumask *mask) { int group = cpu; #ifdef CONFIG_SCHED_MC cpumask_and(mask, cpu_coregroup_mask(cpu), cpu_map); group = cpumask_first(mask); #elif defined(CONFIG_SCHED_SMT) cpumask_and(mask, topology_thread_cpumask(cpu), cpu_map); group = cpumask_first(mask); #endif if (sg) *sg = &per_cpu(sched_group_book, group).sg; return group; } #endif /* CONFIG_SCHED_BOOK */ static DEFINE_PER_CPU(struct static_sched_domain, phys_domains); static DEFINE_PER_CPU(struct static_sched_group, sched_group_phys); static int cpu_to_phys_group(int cpu, const struct cpumask *cpu_map, struct sched_group **sg, struct cpumask *mask) { int group; #ifdef CONFIG_SCHED_BOOK cpumask_and(mask, cpu_book_mask(cpu), cpu_map); group = cpumask_first(mask); #elif defined(CONFIG_SCHED_MC) cpumask_and(mask, cpu_coregroup_mask(cpu), cpu_map); group = cpumask_first(mask); #elif defined(CONFIG_SCHED_SMT) cpumask_and(mask, topology_thread_cpumask(cpu), cpu_map); group = cpumask_first(mask); #else group = cpu; #endif if (sg) *sg = &per_cpu(sched_group_phys, group).sg; 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 static_sched_domain, node_domains); static struct sched_group ***sched_group_nodes_bycpu; static DEFINE_PER_CPU(struct static_sched_domain, allnodes_domains); static DEFINE_PER_CPU(struct static_sched_group, sched_group_allnodes); static int cpu_to_allnodes_group(int cpu, const struct cpumask *cpu_map, struct sched_group **sg, struct cpumask *nodemask) { int group; cpumask_and(nodemask, cpumask_of_node(cpu_to_node(cpu)), cpu_map); group = cpumask_first(nodemask); if (sg) *sg = &per_cpu(sched_group_allnodes, group).sg; 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(j, sched_group_cpus(sg)) { struct sched_domain *sd; sd = &per_cpu(phys_domains, j).sd; if (j != group_first_cpu(sd->groups)) { /* * Only add "power" once for each * physical package. */ continue; } sg->cpu_power += sd->groups->cpu_power; } sg = sg->next; } while (sg != group_head); } static int build_numa_sched_groups(struct s_data *d, const struct cpumask *cpu_map, int num) { struct sched_domain *sd; struct sched_group *sg, *prev; int n, j; cpumask_clear(d->covered); cpumask_and(d->nodemask, cpumask_of_node(num), cpu_map); if (cpumask_empty(d->nodemask)) { d->sched_group_nodes[num] = NULL; goto out; } sched_domain_node_span(num, d->domainspan); cpumask_and(d->domainspan, d->domainspan, cpu_map); sg = kmalloc_node(sizeof(struct sched_group) + cpumask_size(), GFP_KERNEL, num); if (!sg) { printk(KERN_WARNING "Can not alloc domain group for node %d\n", num); return -ENOMEM; } d->sched_group_nodes[num] = sg; for_each_cpu(j, d->nodemask) { sd = &per_cpu(node_domains, j).sd; sd->groups = sg; } sg->cpu_power = 0; cpumask_copy(sched_group_cpus(sg), d->nodemask); sg->next = sg; cpumask_or(d->covered, d->covered, d->nodemask); prev = sg; for (j = 0; j < nr_node_ids; j++) { n = (num + j) % nr_node_ids; cpumask_complement(d->notcovered, d->covered); cpumask_and(d->tmpmask, d->notcovered, cpu_map); cpumask_and(d->tmpmask, d->tmpmask, d->domainspan); if (cpumask_empty(d->tmpmask)) break; cpumask_and(d->tmpmask, d->tmpmask, cpumask_of_node(n)); if (cpumask_empty(d->tmpmask)) continue; sg = kmalloc_node(sizeof(struct sched_group) + cpumask_size(), GFP_KERNEL, num); if (!sg) { printk(KERN_WARNING "Can not alloc domain group for node %d\n", j); return -ENOMEM; } sg->cpu_power = 0; cpumask_copy(sched_group_cpus(sg), d->tmpmask); sg->next = prev->next; cpumask_or(d->covered, d->covered, d->tmpmask); prev->next = sg; prev = sg; } out: return 0; } #endif /* CONFIG_NUMA */ #ifdef CONFIG_NUMA /* Free memory allocated for various sched_group structures */ static void free_sched_groups(const struct cpumask *cpu_map, struct cpumask *nodemask) { int cpu, i; for_each_cpu(cpu, cpu_map) { struct sched_group **sched_group_nodes = sched_group_nodes_bycpu[cpu]; if (!sched_group_nodes) continue; for (i = 0; i < nr_node_ids; i++) { struct sched_group *oldsg, *sg = sched_group_nodes[i]; cpumask_and(nodemask, cpumask_of_node(i), cpu_map); if (cpumask_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 /* !CONFIG_NUMA */ static void free_sched_groups(const struct cpumask *cpu_map, struct cpumask *nodemask) { } #endif /* CONFIG_NUMA */ /* * 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. */ static void init_sched_groups_power(int cpu, struct sched_domain *sd) { struct sched_domain *child; struct sched_group *group; long power; int weight; WARN_ON(!sd || !sd->groups); if (cpu != group_first_cpu(sd->groups)) return; sd->groups->group_weight = cpumask_weight(sched_group_cpus(sd->groups)); child = sd->child; sd->groups->cpu_power = 0; if (!child) { power = SCHED_LOAD_SCALE; weight = cpumask_weight(sched_domain_span(sd)); /* * SMT siblings share the power of a single core. * Usually multiple threads get a better yield out of * that one core than a single thread would have, * reflect that in sd->smt_gain. */ if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) { power *= sd->smt_gain; power /= weight; power >>= SCHED_LOAD_SHIFT; } sd->groups->cpu_power += power; return; } /* * Add cpu_power of each child group to this groups cpu_power. */ group = child->groups; do { sd->groups->cpu_power += group->cpu_power; group = group->next; } while (group != child->groups); } /* * Initializers for schedule domains * Non-inlined to reduce accumulated stack pressure in build_sched_domains() */ #ifdef CONFIG_SCHED_DEBUG # define SD_INIT_NAME(sd, type) sd->name = #type #else # define SD_INIT_NAME(sd, type) do { } while (0) #endif #define SD_INIT(sd, type) sd_init_##type(sd) #define SD_INIT_FUNC(type) \ static noinline void sd_init_##type(struct sched_domain *sd) \ { \ memset(sd, 0, sizeof(*sd)); \ *sd = SD_##type##_INIT; \ sd->level = SD_LV_##type; \ SD_INIT_NAME(sd, type); \ } SD_INIT_FUNC(CPU) #ifdef CONFIG_NUMA SD_INIT_FUNC(ALLNODES) SD_INIT_FUNC(NODE) #endif #ifdef CONFIG_SCHED_SMT SD_INIT_FUNC(SIBLING) #endif #ifdef CONFIG_SCHED_MC SD_INIT_FUNC(MC) #endif #ifdef CONFIG_SCHED_BOOK SD_INIT_FUNC(BOOK) #endif static int default_relax_domain_level = -1; static int __init setup_relax_domain_level(char *str) { unsigned long val; val = simple_strtoul(str, NULL, 0); if (val < SD_LV_MAX) default_relax_domain_level = val; return 1; } __setup("relax_domain_level=", setup_relax_domain_level); static void set_domain_attribute(struct sched_domain *sd, struct sched_domain_attr *attr) { int request; if (!attr || attr->relax_domain_level < 0) { if (default_relax_domain_level < 0) return; else request = default_relax_domain_level; } else request = attr->relax_domain_level; if (request < sd->level) { /* turn off idle balance on this domain */ sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); } else { /* turn on idle balance on this domain */ sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); } } static void __free_domain_allocs(struct s_data *d, enum s_alloc what, const struct cpumask *cpu_map) { switch (what) { case sa_sched_groups: free_sched_groups(cpu_map, d->tmpmask); /* fall through */ d->sched_group_nodes = NULL; case sa_rootdomain: free_rootdomain(d->rd); /* fall through */ case sa_tmpmask: free_cpumask_var(d->tmpmask); /* fall through */ case sa_send_covered: free_cpumask_var(d->send_covered); /* fall through */ case sa_this_book_map: free_cpumask_var(d->this_book_map); /* fall through */ case sa_this_core_map: free_cpumask_var(d->this_core_map); /* fall through */ case sa_this_sibling_map: free_cpumask_var(d->this_sibling_map); /* fall through */ case sa_nodemask: free_cpumask_var(d->nodemask); /* fall through */ case sa_sched_group_nodes: #ifdef CONFIG_NUMA kfree(d->sched_group_nodes); /* fall through */ case sa_notcovered: free_cpumask_var(d->notcovered); /* fall through */ case sa_covered: free_cpumask_var(d->covered); /* fall through */ case sa_domainspan: free_cpumask_var(d->domainspan); /* fall through */ #endif case sa_none: break; } } static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map) { #ifdef CONFIG_NUMA if (!alloc_cpumask_var(&d->domainspan, GFP_KERNEL)) return sa_none; if (!alloc_cpumask_var(&d->covered, GFP_KERNEL)) return sa_domainspan; if (!alloc_cpumask_var(&d->notcovered, GFP_KERNEL)) return sa_covered; /* Allocate the per-node list of sched groups */ d->sched_group_nodes = kcalloc(nr_node_ids, sizeof(struct sched_group *), GFP_KERNEL); if (!d->sched_group_nodes) { printk(KERN_WARNING "Can not alloc sched group node list\n"); return sa_notcovered; } sched_group_nodes_bycpu[cpumask_first(cpu_map)] = d->sched_group_nodes; #endif if (!alloc_cpumask_var(&d->nodemask, GFP_KERNEL)) return sa_sched_group_nodes; if (!alloc_cpumask_var(&d->this_sibling_map, GFP_KERNEL)) return sa_nodemask; if (!alloc_cpumask_var(&d->this_core_map, GFP_KERNEL)) return sa_this_sibling_map; if (!alloc_cpumask_var(&d->this_book_map, GFP_KERNEL)) return sa_this_core_map; if (!alloc_cpumask_var(&d->send_covered, GFP_KERNEL)) return sa_this_book_map; if (!alloc_cpumask_var(&d->tmpmask, GFP_KERNEL)) return sa_send_covered; d->rd = alloc_rootdomain(); if (!d->rd) { printk(KERN_WARNING "Cannot alloc root domain\n"); return sa_tmpmask; } return sa_rootdomain; } static struct sched_domain *__build_numa_sched_domains(struct s_data *d, const struct cpumask *cpu_map, struct sched_domain_attr *attr, int i) { struct sched_domain *sd = NULL; #ifdef CONFIG_NUMA struct sched_domain *parent; d->sd_allnodes = 0; if (cpumask_weight(cpu_map) > SD_NODES_PER_DOMAIN * cpumask_weight(d->nodemask)) { sd = &per_cpu(allnodes_domains, i).sd; SD_INIT(sd, ALLNODES); set_domain_attribute(sd, attr); cpumask_copy(sched_domain_span(sd), cpu_map); cpu_to_allnodes_group(i, cpu_map, &sd->groups, d->tmpmask); d->sd_allnodes = 1; } parent = sd; sd = &per_cpu(node_domains, i).sd; SD_INIT(sd, NODE); set_domain_attribute(sd, attr); sched_domain_node_span(cpu_to_node(i), sched_domain_span(sd)); sd->parent = parent; if (parent) parent->child = sd; cpumask_and(sched_domain_span(sd), sched_domain_span(sd), cpu_map); #endif return sd; } static struct sched_domain *__build_cpu_sched_domain(struct s_data *d, const struct cpumask *cpu_map, struct sched_domain_attr *attr, struct sched_domain *parent, int i) { struct sched_domain *sd; sd = &per_cpu(phys_domains, i).sd; SD_INIT(sd, CPU); set_domain_attribute(sd, attr); cpumask_copy(sched_domain_span(sd), d->nodemask); sd->parent = parent; if (parent) parent->child = sd; cpu_to_phys_group(i, cpu_map, &sd->groups, d->tmpmask); return sd; } static struct sched_domain *__build_book_sched_domain(struct s_data *d, const struct cpumask *cpu_map, struct sched_domain_attr *attr, struct sched_domain *parent, int i) { struct sched_domain *sd = parent; #ifdef CONFIG_SCHED_BOOK sd = &per_cpu(book_domains, i).sd; SD_INIT(sd, BOOK); set_domain_attribute(sd, attr); cpumask_and(sched_domain_span(sd), cpu_map, cpu_book_mask(i)); sd->parent = parent; parent->child = sd; cpu_to_book_group(i, cpu_map, &sd->groups, d->tmpmask); #endif return sd; } static struct sched_domain *__build_mc_sched_domain(struct s_data *d, const struct cpumask *cpu_map, struct sched_domain_attr *attr, struct sched_domain *parent, int i) { struct sched_domain *sd = parent; #ifdef CONFIG_SCHED_MC sd = &per_cpu(core_domains, i).sd; SD_INIT(sd, MC); set_domain_attribute(sd, attr); cpumask_and(sched_domain_span(sd), cpu_map, cpu_coregroup_mask(i)); sd->parent = parent; parent->child = sd; cpu_to_core_group(i, cpu_map, &sd->groups, d->tmpmask); #endif return sd; } static struct sched_domain *__build_smt_sched_domain(struct s_data *d, const struct cpumask *cpu_map, struct sched_domain_attr *attr, struct sched_domain *parent, int i) { struct sched_domain *sd = parent; #ifdef CONFIG_SCHED_SMT sd = &per_cpu(cpu_domains, i).sd; SD_INIT(sd, SIBLING); set_domain_attribute(sd, attr); cpumask_and(sched_domain_span(sd), cpu_map, topology_thread_cpumask(i)); sd->parent = parent; parent->child = sd; cpu_to_cpu_group(i, cpu_map, &sd->groups, d->tmpmask); #endif return sd; } static void build_sched_groups(struct s_data *d, enum sched_domain_level l, const struct cpumask *cpu_map, int cpu) { switch (l) { #ifdef CONFIG_SCHED_SMT case SD_LV_SIBLING: /* set up CPU (sibling) groups */ cpumask_and(d->this_sibling_map, cpu_map, topology_thread_cpumask(cpu)); if (cpu == cpumask_first(d->this_sibling_map)) init_sched_build_groups(d->this_sibling_map, cpu_map, &cpu_to_cpu_group, d->send_covered, d->tmpmask); break; #endif #ifdef CONFIG_SCHED_MC case SD_LV_MC: /* set up multi-core groups */ cpumask_and(d->this_core_map, cpu_map, cpu_coregroup_mask(cpu)); if (cpu == cpumask_first(d->this_core_map)) init_sched_build_groups(d->this_core_map, cpu_map, &cpu_to_core_group, d->send_covered, d->tmpmask); break; #endif #ifdef CONFIG_SCHED_BOOK case SD_LV_BOOK: /* set up book groups */ cpumask_and(d->this_book_map, cpu_map, cpu_book_mask(cpu)); if (cpu == cpumask_first(d->this_book_map)) init_sched_build_groups(d->this_book_map, cpu_map, &cpu_to_book_group, d->send_covered, d->tmpmask); break; #endif case SD_LV_CPU: /* set up physical groups */ cpumask_and(d->nodemask, cpumask_of_node(cpu), cpu_map); if (!cpumask_empty(d->nodemask)) init_sched_build_groups(d->nodemask, cpu_map, &cpu_to_phys_group, d->send_covered, d->tmpmask); break; #ifdef CONFIG_NUMA case SD_LV_ALLNODES: init_sched_build_groups(cpu_map, cpu_map, &cpu_to_allnodes_group, d->send_covered, d->tmpmask); break; #endif default: break; } } /* * Build sched domains for a given set of cpus and attach the sched domains * to the individual cpus */ static int __build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr) { enum s_alloc alloc_state = sa_none; struct s_data d; struct sched_domain *sd; int i; #ifdef CONFIG_NUMA d.sd_allnodes = 0; #endif alloc_state = __visit_domain_allocation_hell(&d, cpu_map); if (alloc_state != sa_rootdomain) goto error; alloc_state = sa_sched_groups; /* * Set up domains for cpus specified by the cpu_map. */ for_each_cpu(i, cpu_map) { cpumask_and(d.nodemask, cpumask_of_node(cpu_to_node(i)), cpu_map); sd = __build_numa_sched_domains(&d, cpu_map, attr, i); sd = __build_cpu_sched_domain(&d, cpu_map, attr, sd, i); sd = __build_book_sched_domain(&d, cpu_map, attr, sd, i); sd = __build_mc_sched_domain(&d, cpu_map, attr, sd, i); sd = __build_smt_sched_domain(&d, cpu_map, attr, sd, i); } for_each_cpu(i, cpu_map) { build_sched_groups(&d, SD_LV_SIBLING, cpu_map, i); build_sched_groups(&d, SD_LV_BOOK, cpu_map, i); build_sched_groups(&d, SD_LV_MC, cpu_map, i); } /* Set up physical groups */ for (i = 0; i < nr_node_ids; i++) build_sched_groups(&d, SD_LV_CPU, cpu_map, i); #ifdef CONFIG_NUMA /* Set up node groups */ if (d.sd_allnodes) build_sched_groups(&d, SD_LV_ALLNODES, cpu_map, 0); for (i = 0; i < nr_node_ids; i++) if (build_numa_sched_groups(&d, cpu_map, i)) goto error; #endif /* Calculate CPU power for physical packages and nodes */ #ifdef CONFIG_SCHED_SMT for_each_cpu(i, cpu_map) { sd = &per_cpu(cpu_domains, i).sd; init_sched_groups_power(i, sd); } #endif #ifdef CONFIG_SCHED_MC for_each_cpu(i, cpu_map) { sd = &per_cpu(core_domains, i).sd; init_sched_groups_power(i, sd); } #endif #ifdef CONFIG_SCHED_BOOK for_each_cpu(i, cpu_map) { sd = &per_cpu(book_domains, i).sd; init_sched_groups_power(i, sd); } #endif for_each_cpu(i, cpu_map) { sd = &per_cpu(phys_domains, i).sd; init_sched_groups_power(i, sd); } #ifdef CONFIG_NUMA for (i = 0; i < nr_node_ids; i++) init_numa_sched_groups_power(d.sched_group_nodes[i]); if (d.sd_allnodes) { struct sched_group *sg; cpu_to_allnodes_group(cpumask_first(cpu_map), cpu_map, &sg, d.tmpmask); init_numa_sched_groups_power(sg); } #endif /* Attach the domains */ for_each_cpu(i, cpu_map) { #ifdef CONFIG_SCHED_SMT sd = &per_cpu(cpu_domains, i).sd; #elif defined(CONFIG_SCHED_MC) sd = &per_cpu(core_domains, i).sd; #elif defined(CONFIG_SCHED_BOOK) sd = &per_cpu(book_domains, i).sd; #else sd = &per_cpu(phys_domains, i).sd; #endif cpu_attach_domain(sd, d.rd, i); } d.sched_group_nodes = NULL; /* don't free this we still need it */ __free_domain_allocs(&d, sa_tmpmask, cpu_map); return 0; error: __free_domain_allocs(&d, alloc_state, cpu_map); return -ENOMEM; } static int build_sched_domains(const struct cpumask *cpu_map) { return __build_sched_domains(cpu_map, NULL); } static cpumask_var_t *doms_cur; /* current sched domains */ static int ndoms_cur; /* number of sched domains in 'doms_cur' */ static struct sched_domain_attr *dattr_cur; /* attribues of custom domains in 'doms_cur' */ /* * Special case: If a kmalloc of a doms_cur partition (array of * cpumask) fails, then fallback to a single sched domain, * as determined by the single cpumask fallback_doms. */ static cpumask_var_t fallback_doms; /* * arch_update_cpu_topology lets virtualized architectures update the * cpu core maps. It is supposed to return 1 if the topology changed * or 0 if it stayed the same. */ int __attribute__((weak)) arch_update_cpu_topology(void) { return 0; } cpumask_var_t *alloc_sched_domains(unsigned int ndoms) { int i; cpumask_var_t *doms; doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL); if (!doms) return NULL; for (i = 0; i < ndoms; i++) { if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { free_sched_domains(doms, i); return NULL; } } return doms; } void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) { unsigned int i; for (i = 0; i < ndoms; i++) free_cpumask_var(doms[i]); kfree(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 struct cpumask *cpu_map) { int err; arch_update_cpu_topology(); ndoms_cur = 1; doms_cur = alloc_sched_domains(ndoms_cur); if (!doms_cur) doms_cur = &fallback_doms; cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map); dattr_cur = NULL; err = build_sched_domains(doms_cur[0]); register_sched_domain_sysctl(); return err; } static void arch_destroy_sched_domains(const struct cpumask *cpu_map, struct cpumask *tmpmask) { free_sched_groups(cpu_map, tmpmask); } /* * 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 struct cpumask *cpu_map) { /* Save because hotplug lock held. */ static DECLARE_BITMAP(tmpmask, CONFIG_NR_CPUS); int i; for_each_cpu(i, cpu_map) cpu_attach_domain(NULL, &def_root_domain, i); synchronize_sched(); arch_destroy_sched_domains(cpu_map, to_cpumask(tmpmask)); } /* handle null as "default" */ static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, struct sched_domain_attr *new, int idx_new) { struct sched_domain_attr tmp; /* fast path */ if (!new && !cur) return 1; tmp = SD_ATTR_INIT; return !memcmp(cur ? (cur + idx_cur) : &tmp, new ? (new + idx_new) : &tmp, sizeof(struct sched_domain_attr)); } /* * 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_var_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 allocated using * alloc_sched_domains. This routine takes ownership of it and will * free_sched_domains it when done with it. If the caller failed the * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, * and partition_sched_domains() will fallback to the single partition * 'fallback_doms', it also forces the domains to be rebuilt. * * If doms_new == NULL it will be replaced with cpu_online_mask. * ndoms_new == 0 is a special case for destroying existing domains, * and it will not create the default domain. * * Call with hotplug lock held */ void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], struct sched_domain_attr *dattr_new) { int i, j, n; int new_topology; mutex_lock(&sched_domains_mutex); /* always unregister in case we don't destroy any domains */ unregister_sched_domain_sysctl(); /* Let architecture update cpu core mappings. */ new_topology = arch_update_cpu_topology(); n = doms_new ? ndoms_new : 0; /* Destroy deleted domains */ for (i = 0; i < ndoms_cur; i++) { for (j = 0; j < n && !new_topology; j++) { if (cpumask_equal(doms_cur[i], doms_new[j]) && dattrs_equal(dattr_cur, i, dattr_new, j)) goto match1; } /* no match - a current sched domain not in new doms_new[] */ detach_destroy_domains(doms_cur[i]); match1: ; } if (doms_new == NULL) { ndoms_cur = 0; doms_new = &fallback_doms; cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); WARN_ON_ONCE(dattr_new); } /* Build new domains */ for (i = 0; i < ndoms_new; i++) { for (j = 0; j < ndoms_cur && !new_topology; j++) { if (cpumask_equal(doms_new[i], doms_cur[j]) && dattrs_equal(dattr_new, i, dattr_cur, j)) goto match2; } /* no match - add a new doms_new */ __build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); match2: ; } /* Remember the new sched domains */ if (doms_cur != &fallback_doms) free_sched_domains(doms_cur, ndoms_cur); kfree(dattr_cur); /* kfree(NULL) is safe */ doms_cur = doms_new; dattr_cur = dattr_new; ndoms_cur = ndoms_new; register_sched_domain_sysctl(); mutex_unlock(&sched_domains_mutex); } #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) static void arch_reinit_sched_domains(void) { get_online_cpus(); /* Destroy domains first to force the rebuild */ partition_sched_domains(0, NULL, NULL); rebuild_sched_domains(); put_online_cpus(); } static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt) { unsigned int level = 0; if (sscanf(buf, "%u", &level) != 1) return -EINVAL; /* * level is always be positive so don't check for * level < POWERSAVINGS_BALANCE_NONE which is 0 * What happens on 0 or 1 byte write, * need to check for count as well? */ if (level >= MAX_POWERSAVINGS_BALANCE_LEVELS) return -EINVAL; if (smt) sched_smt_power_savings = level; else sched_mc_power_savings = level; arch_reinit_sched_domains(); return count; } #ifdef CONFIG_SCHED_MC static ssize_t sched_mc_power_savings_show(struct sysdev_class *class, struct sysdev_class_attribute *attr, char *page) { return sprintf(page, "%u\n", sched_mc_power_savings); } static ssize_t sched_mc_power_savings_store(struct sysdev_class *class, struct sysdev_class_attribute *attr, const char *buf, size_t count) { return sched_power_savings_store(buf, count, 0); } static SYSDEV_CLASS_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 sysdev_class *dev, struct sysdev_class_attribute *attr, char *page) { return sprintf(page, "%u\n", sched_smt_power_savings); } static ssize_t sched_smt_power_savings_store(struct sysdev_class *dev, struct sysdev_class_attribute *attr, const char *buf, size_t count) { return sched_power_savings_store(buf, count, 1); } static SYSDEV_CLASS_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show, sched_smt_power_savings_store); #endif int __init 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 /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */ /* * Update cpusets according to cpu_active mask. If cpusets are * disabled, cpuset_update_active_cpus() becomes a simple wrapper * around partition_sched_domains(). */ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, void *hcpu) { switch (action & ~CPU_TASKS_FROZEN) { case CPU_ONLINE: case CPU_DOWN_FAILED: cpuset_update_active_cpus(); return NOTIFY_OK; default: return NOTIFY_DONE; } } static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, void *hcpu) { switch (action & ~CPU_TASKS_FROZEN) { case CPU_DOWN_PREPARE: cpuset_update_active_cpus(); return NOTIFY_OK; default: return NOTIFY_DONE; } } static int update_runtime(struct notifier_block *nfb, unsigned long action, void *hcpu) { int cpu = (int)(long)hcpu; switch (action) { case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN: disable_runtime(cpu_rq(cpu)); return NOTIFY_OK; case CPU_DOWN_FAILED: case CPU_DOWN_FAILED_FROZEN: case CPU_ONLINE: case CPU_ONLINE_FROZEN: enable_runtime(cpu_rq(cpu)); return NOTIFY_OK; default: return NOTIFY_DONE; } } void __init sched_init_smp(void) { cpumask_var_t non_isolated_cpus; alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); alloc_cpumask_var(&fallback_doms, GFP_KERNEL); #if defined(CONFIG_NUMA) sched_group_nodes_bycpu = kzalloc(nr_cpu_ids * sizeof(void **), GFP_KERNEL); BUG_ON(sched_group_nodes_bycpu == NULL); #endif get_online_cpus(); mutex_lock(&sched_domains_mutex); arch_init_sched_domains(cpu_active_mask); cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); if (cpumask_empty(non_isolated_cpus)) cpumask_set_cpu(smp_processor_id(), non_isolated_cpus); mutex_unlock(&sched_domains_mutex); put_online_cpus(); hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE); hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE); /* RT runtime code needs to handle some hotplug events */ hotcpu_notifier(update_runtime, 0); init_hrtick(); /* Move init over to a non-isolated CPU */ if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) BUG(); sched_init_granularity(); free_cpumask_var(non_isolated_cpus); init_sched_rt_class(); } #else void __init sched_init_smp(void) { sched_init_granularity(); } #endif /* CONFIG_SMP */ const_debug unsigned int sysctl_timer_migration = 1; int in_sched_functions(unsigned long addr) { 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; INIT_LIST_HEAD(&cfs_rq->tasks); #ifdef CONFIG_FAIR_GROUP_SCHED cfs_rq->rq = rq; #endif cfs_rq->min_vruntime = (u64)(-(1LL << 20)); } static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq) { struct rt_prio_array *array; int i; array = &rt_rq->active; for (i = 0; i < MAX_RT_PRIO; i++) { INIT_LIST_HEAD(array->queue + i); __clear_bit(i, array->bitmap); } /* delimiter for bitsearch: */ __set_bit(MAX_RT_PRIO, array->bitmap); #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED rt_rq->highest_prio.curr = MAX_RT_PRIO; #ifdef CONFIG_SMP rt_rq->highest_prio.next = MAX_RT_PRIO; #endif #endif #ifdef CONFIG_SMP rt_rq->rt_nr_migratory = 0; rt_rq->overloaded = 0; plist_head_init_raw(&rt_rq->pushable_tasks, &rq->lock); #endif rt_rq->rt_time = 0; rt_rq->rt_throttled = 0; rt_rq->rt_runtime = 0; raw_spin_lock_init(&rt_rq->rt_runtime_lock); #ifdef CONFIG_RT_GROUP_SCHED rt_rq->rt_nr_boosted = 0; rt_rq->rq = rq; #endif } #ifdef CONFIG_FAIR_GROUP_SCHED static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, struct sched_entity *se, int cpu, int add, struct sched_entity *parent) { struct rq *rq = cpu_rq(cpu); tg->cfs_rq[cpu] = cfs_rq; init_cfs_rq(cfs_rq, rq); cfs_rq->tg = tg; if (add) list_add(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list); tg->se[cpu] = se; /* se could be NULL for init_task_group */ if (!se) return; if (!parent) se->cfs_rq = &rq->cfs; else se->cfs_rq = parent->my_q; se->my_q = cfs_rq; se->load.weight = tg->shares; se->load.inv_weight = 0; se->parent = parent; } #endif #ifdef CONFIG_RT_GROUP_SCHED static void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int cpu, int add, struct sched_rt_entity *parent) { struct rq *rq = cpu_rq(cpu); tg->rt_rq[cpu] = rt_rq; init_rt_rq(rt_rq, rq); rt_rq->tg = tg; rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime; if (add) list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list); tg->rt_se[cpu] = rt_se; if (!rt_se) return; if (!parent) rt_se->rt_rq = &rq->rt; else rt_se->rt_rq = parent->my_q; rt_se->my_q = rt_rq; rt_se->parent = parent; INIT_LIST_HEAD(&rt_se->run_list); } #endif void __init sched_init(void) { int i, j; unsigned long alloc_size = 0, ptr; #ifdef CONFIG_FAIR_GROUP_SCHED alloc_size += 2 * nr_cpu_ids * sizeof(void **); #endif #ifdef CONFIG_RT_GROUP_SCHED alloc_size += 2 * nr_cpu_ids * sizeof(void **); #endif #ifdef CONFIG_CPUMASK_OFFSTACK alloc_size += num_possible_cpus() * cpumask_size(); #endif if (alloc_size) { ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); #ifdef CONFIG_FAIR_GROUP_SCHED init_task_group.se = (struct sched_entity **)ptr; ptr += nr_cpu_ids * sizeof(void **); init_task_group.cfs_rq = (struct cfs_rq **)ptr; ptr += nr_cpu_ids * sizeof(void **); #endif /* CONFIG_FAIR_GROUP_SCHED */ #ifdef CONFIG_RT_GROUP_SCHED init_task_group.rt_se = (struct sched_rt_entity **)ptr; ptr += nr_cpu_ids * sizeof(void **); init_task_group.rt_rq = (struct rt_rq **)ptr; ptr += nr_cpu_ids * sizeof(void **); #endif /* CONFIG_RT_GROUP_SCHED */ #ifdef CONFIG_CPUMASK_OFFSTACK for_each_possible_cpu(i) { per_cpu(load_balance_tmpmask, i) = (void *)ptr; ptr += cpumask_size(); } #endif /* CONFIG_CPUMASK_OFFSTACK */ } #ifdef CONFIG_SMP init_defrootdomain(); #endif init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime()); #ifdef CONFIG_RT_GROUP_SCHED init_rt_bandwidth(&init_task_group.rt_bandwidth, global_rt_period(), global_rt_runtime()); #endif /* CONFIG_RT_GROUP_SCHED */ #ifdef CONFIG_CGROUP_SCHED list_add(&init_task_group.list, &task_groups); INIT_LIST_HEAD(&init_task_group.children); #endif /* CONFIG_CGROUP_SCHED */ #if defined CONFIG_FAIR_GROUP_SCHED && defined CONFIG_SMP update_shares_data = __alloc_percpu(nr_cpu_ids * sizeof(unsigned long), __alignof__(unsigned long)); #endif for_each_possible_cpu(i) { struct rq *rq; rq = cpu_rq(i); raw_spin_lock_init(&rq->lock); rq->nr_running = 0; rq->calc_load_active = 0; rq->calc_load_update = jiffies + LOAD_FREQ; init_cfs_rq(&rq->cfs, rq); init_rt_rq(&rq->rt, rq); #ifdef CONFIG_FAIR_GROUP_SCHED init_task_group.shares = init_task_group_load; INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); #ifdef CONFIG_CGROUP_SCHED /* * How much cpu bandwidth does init_task_group get? * * In case of task-groups formed thr' the cgroup filesystem, it * gets 100% of the cpu resources in the system. This overall * system cpu resource is divided among the tasks of * init_task_group and its child task-groups in a fair manner, * based on each entity's (task or task-group's) weight * (se->load.weight). * * In other words, if init_task_group has 10 tasks of weight * 1024) and two child groups A0 and A1 (of weight 1024 each), * then A0's share of the cpu resource is: * * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% * * We achieve this by letting init_task_group's tasks sit * directly in rq->cfs (i.e init_task_group->se[] = NULL). */ init_tg_cfs_entry(&init_task_group, &rq->cfs, NULL, i, 1, NULL); #endif #endif /* CONFIG_FAIR_GROUP_SCHED */ rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; #ifdef CONFIG_RT_GROUP_SCHED INIT_LIST_HEAD(&rq->leaf_rt_rq_list); #ifdef CONFIG_CGROUP_SCHED init_tg_rt_entry(&init_task_group, &rq->rt, NULL, i, 1, NULL); #endif #endif for (j = 0; j < CPU_LOAD_IDX_MAX; j++) rq->cpu_load[j] = 0; rq->last_load_update_tick = jiffies; #ifdef CONFIG_SMP rq->sd = NULL; rq->rd = NULL; rq->cpu_power = SCHED_LOAD_SCALE; rq->post_schedule = 0; rq->active_balance = 0; rq->next_balance = jiffies; rq->push_cpu = 0; rq->cpu = i; rq->online = 0; rq->idle_stamp = 0; rq->avg_idle = 2*sysctl_sched_migration_cost; rq_attach_root(rq, &def_root_domain); #ifdef CONFIG_NO_HZ rq->nohz_balance_kick = 0; init_sched_softirq_csd(&per_cpu(remote_sched_softirq_cb, i)); #endif #endif init_rq_hrtick(rq); atomic_set(&rq->nr_iowait, 0); } set_load_weight(&init_task); #ifdef CONFIG_PREEMPT_NOTIFIERS INIT_HLIST_HEAD(&init_task.preempt_notifiers); #endif #ifdef CONFIG_SMP open_softirq(SCHED_SOFTIRQ, run_rebalance_domains); #endif #ifdef CONFIG_RT_MUTEXES plist_head_init_raw(&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()); calc_load_update = jiffies + LOAD_FREQ; /* * During early bootup we pretend to be a normal task: */ current->sched_class = &fair_sched_class; /* Allocate the nohz_cpu_mask if CONFIG_CPUMASK_OFFSTACK */ zalloc_cpumask_var(&nohz_cpu_mask, GFP_NOWAIT); #ifdef CONFIG_SMP #ifdef CONFIG_NO_HZ zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); alloc_cpumask_var(&nohz.grp_idle_mask, GFP_NOWAIT); atomic_set(&nohz.load_balancer, nr_cpu_ids); atomic_set(&nohz.first_pick_cpu, nr_cpu_ids); atomic_set(&nohz.second_pick_cpu, nr_cpu_ids); #endif /* May be allocated at isolcpus cmdline parse time */ if (cpu_isolated_map == NULL) zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT); #endif /* SMP */ perf_event_init(); scheduler_running = 1; } #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP static inline int preempt_count_equals(int preempt_offset) { int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth(); return (nested == PREEMPT_INATOMIC_BASE + preempt_offset); } void __might_sleep(const char *file, int line, int preempt_offset) { #ifdef in_atomic static unsigned long prev_jiffy; /* ratelimiting */ if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) || system_state != SYSTEM_RUNNING || oops_in_progress) return; 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(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", in_atomic(), irqs_disabled(), current->pid, current->comm); 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; 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_irqsave(&tasklist_lock, flags); do_each_thread(g, p) { /* * Only normalize user tasks: */ if (!p->mm) continue; p->se.exec_start = 0; #ifdef CONFIG_SCHEDSTATS p->se.statistics.wait_start = 0; p->se.statistics.sleep_start = 0; p->se.statistics.block_start = 0; #endif 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; } raw_spin_lock(&p->pi_lock); rq = __task_rq_lock(p); normalize_task(rq, p); __task_rq_unlock(rq); raw_spin_unlock(&p->pi_lock); } while_each_thread(g, p); read_unlock_irqrestore(&tasklist_lock, flags); } #endif /* CONFIG_MAGIC_SYSRQ */ #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) /* * These functions are only useful for the IA64 MCA handling, or kdb. * * 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); } #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ #ifdef CONFIG_IA64 /** * 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 static void free_fair_sched_group(struct task_group *tg) { int i; 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); } static int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) { struct cfs_rq *cfs_rq; struct sched_entity *se; struct rq *rq; int i; tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL); if (!tg->cfs_rq) goto err; tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL); if (!tg->se) goto err; tg->shares = NICE_0_LOAD; for_each_possible_cpu(i) { rq = cpu_rq(i); cfs_rq = kzalloc_node(sizeof(struct cfs_rq), GFP_KERNEL, cpu_to_node(i)); if (!cfs_rq) goto err; se = kzalloc_node(sizeof(struct sched_entity), GFP_KERNEL, cpu_to_node(i)); if (!se) goto err_free_rq; init_tg_cfs_entry(tg, cfs_rq, se, i, 0, parent->se[i]); } return 1; err_free_rq: kfree(cfs_rq); err: return 0; } static inline void register_fair_sched_group(struct task_group *tg, int cpu) { list_add_rcu(&tg->cfs_rq[cpu]->leaf_cfs_rq_list, &cpu_rq(cpu)->leaf_cfs_rq_list); } static inline void unregister_fair_sched_group(struct task_group *tg, int cpu) { list_del_rcu(&tg->cfs_rq[cpu]->leaf_cfs_rq_list); } #else /* !CONFG_FAIR_GROUP_SCHED */ static inline void free_fair_sched_group(struct task_group *tg) { } static inline int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) { return 1; } static inline void register_fair_sched_group(struct task_group *tg, int cpu) { } static inline void unregister_fair_sched_group(struct task_group *tg, int cpu) { } #endif /* CONFIG_FAIR_GROUP_SCHED */ #ifdef CONFIG_RT_GROUP_SCHED static void free_rt_sched_group(struct task_group *tg) { int i; destroy_rt_bandwidth(&tg->rt_bandwidth); for_each_possible_cpu(i) { if (tg->rt_rq) kfree(tg->rt_rq[i]); if (tg->rt_se) kfree(tg->rt_se[i]); } kfree(tg->rt_rq); kfree(tg->rt_se); } static int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) { struct rt_rq *rt_rq; struct sched_rt_entity *rt_se; struct rq *rq; int i; tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL); if (!tg->rt_rq) goto err; tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL); if (!tg->rt_se) goto err; init_rt_bandwidth(&tg->rt_bandwidth, ktime_to_ns(def_rt_bandwidth.rt_period), 0); for_each_possible_cpu(i) { rq = cpu_rq(i); rt_rq = kzalloc_node(sizeof(struct rt_rq), GFP_KERNEL, cpu_to_node(i)); if (!rt_rq) goto err; rt_se = kzalloc_node(sizeof(struct sched_rt_entity), GFP_KERNEL, cpu_to_node(i)); if (!rt_se) goto err_free_rq; init_tg_rt_entry(tg, rt_rq, rt_se, i, 0, parent->rt_se[i]); } return 1; err_free_rq: kfree(rt_rq); err: return 0; } static inline void register_rt_sched_group(struct task_group *tg, int cpu) { list_add_rcu(&tg->rt_rq[cpu]->leaf_rt_rq_list, &cpu_rq(cpu)->leaf_rt_rq_list); } static inline void unregister_rt_sched_group(struct task_group *tg, int cpu) { list_del_rcu(&tg->rt_rq[cpu]->leaf_rt_rq_list); } #else /* !CONFIG_RT_GROUP_SCHED */ static inline void free_rt_sched_group(struct task_group *tg) { } static inline int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) { return 1; } static inline void register_rt_sched_group(struct task_group *tg, int cpu) { } static inline void unregister_rt_sched_group(struct task_group *tg, int cpu) { } #endif /* CONFIG_RT_GROUP_SCHED */ #ifdef CONFIG_CGROUP_SCHED static void free_sched_group(struct task_group *tg) { free_fair_sched_group(tg); free_rt_sched_group(tg); kfree(tg); } /* allocate runqueue etc for a new task group */ struct task_group *sched_create_group(struct task_group *parent) { struct task_group *tg; unsigned long flags; int i; tg = kzalloc(sizeof(*tg), GFP_KERNEL); if (!tg) return ERR_PTR(-ENOMEM); if (!alloc_fair_sched_group(tg, parent)) goto err; if (!alloc_rt_sched_group(tg, parent)) goto err; spin_lock_irqsave(&task_group_lock, flags); for_each_possible_cpu(i) { register_fair_sched_group(tg, i); register_rt_sched_group(tg, i); } list_add_rcu(&tg->list, &task_groups); WARN_ON(!parent); /* root should already exist */ tg->parent = parent; INIT_LIST_HEAD(&tg->children); list_add_rcu(&tg->siblings, &parent->children); spin_unlock_irqrestore(&task_group_lock, flags); return tg; err: free_sched_group(tg); return ERR_PTR(-ENOMEM); } /* rcu callback to free various structures associated with a task group */ static void free_sched_group_rcu(struct rcu_head *rhp) { /* now it should be safe to free those cfs_rqs */ free_sched_group(container_of(rhp, struct task_group, rcu)); } /* Destroy runqueue etc associated with a task group */ void sched_destroy_group(struct task_group *tg) { unsigned long flags; int i; spin_lock_irqsave(&task_group_lock, flags); for_each_possible_cpu(i) { unregister_fair_sched_group(tg, i); unregister_rt_sched_group(tg, i); } list_del_rcu(&tg->list); list_del_rcu(&tg->siblings); spin_unlock_irqrestore(&task_group_lock, flags); /* wait for possible concurrent references to cfs_rqs complete */ call_rcu(&tg->rcu, free_sched_group_rcu); } /* 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); running = task_current(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); #ifdef CONFIG_FAIR_GROUP_SCHED if (tsk->sched_class->task_move_group) tsk->sched_class->task_move_group(tsk, on_rq); else #endif set_task_rq(tsk, task_cpu(tsk)); if (unlikely(running)) tsk->sched_class->set_curr_task(rq); if (on_rq) enqueue_task(rq, tsk, 0); task_rq_unlock(rq, &flags); } #endif /* CONFIG_CGROUP_SCHED */ #ifdef CONFIG_FAIR_GROUP_SCHED static void __set_se_shares(struct sched_entity *se, unsigned long shares) { struct cfs_rq *cfs_rq = se->cfs_rq; int on_rq; on_rq = se->on_rq; if (on_rq) dequeue_entity(cfs_rq, se, 0); se->load.weight = shares; se->load.inv_weight = 0; if (on_rq) enqueue_entity(cfs_rq, se, 0); } 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; unsigned long flags; raw_spin_lock_irqsave(&rq->lock, flags); __set_se_shares(se, shares); raw_spin_unlock_irqrestore(&rq->lock, flags); } static DEFINE_MUTEX(shares_mutex); int sched_group_set_shares(struct task_group *tg, unsigned long shares) { int i; unsigned long flags; /* * We can't change the weight of the root cgroup. */ if (!tg->se[0]) return -EINVAL; if (shares < MIN_SHARES) shares = MIN_SHARES; else if (shares > MAX_SHARES) shares = MAX_SHARES; mutex_lock(&shares_mutex); if (tg->shares == shares) goto done; spin_lock_irqsave(&task_group_lock, flags); for_each_possible_cpu(i) unregister_fair_sched_group(tg, i); list_del_rcu(&tg->siblings); spin_unlock_irqrestore(&task_group_lock, flags); /* wait for any ongoing reference to this group to finish */ synchronize_sched(); /* * Now we are free to modify the group's share on each cpu * w/o tripping rebalance_share or load_balance_fair. */ tg->shares = shares; for_each_possible_cpu(i) { /* * force a rebalance */ cfs_rq_set_shares(tg->cfs_rq[i], 0); set_se_shares(tg->se[i], shares); } /* * Enable load balance activity on this group, by inserting it back on * each cpu's rq->leaf_cfs_rq_list. */ spin_lock_irqsave(&task_group_lock, flags); for_each_possible_cpu(i) register_fair_sched_group(tg, i); list_add_rcu(&tg->siblings, &tg->parent->children); spin_unlock_irqrestore(&task_group_lock, flags); done: mutex_unlock(&shares_mutex); return 0; } unsigned long sched_group_shares(struct task_group *tg) { return tg->shares; } #endif #ifdef CONFIG_RT_GROUP_SCHED /* * Ensure that the real time constraints are schedulable. */ static DEFINE_MUTEX(rt_constraints_mutex); static unsigned long to_ratio(u64 period, u64 runtime) { if (runtime == RUNTIME_INF) return 1ULL << 20; return div64_u64(runtime << 20, period); } /* Must be called with tasklist_lock held */ static inline int tg_has_rt_tasks(struct task_group *tg) { struct task_struct *g, *p; do_each_thread(g, p) { if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg) return 1; } while_each_thread(g, p); return 0; } struct rt_schedulable_data { struct task_group *tg; u64 rt_period; u64 rt_runtime; }; static int tg_schedulable(struct task_group *tg, void *data) { struct rt_schedulable_data *d = data; struct task_group *child; unsigned long total, sum = 0; u64 period, runtime; period = ktime_to_ns(tg->rt_bandwidth.rt_period); runtime = tg->rt_bandwidth.rt_runtime; if (tg == d->tg) { period = d->rt_period; runtime = d->rt_runtime; } /* * Cannot have more runtime than the period. */ if (runtime > period && runtime != RUNTIME_INF) return -EINVAL; /* * Ensure we don't starve existing RT tasks. */ if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg)) return -EBUSY; total = to_ratio(period, runtime); /* * Nobody can have more than the global setting allows. */ if (total > to_ratio(global_rt_period(), global_rt_runtime())) return -EINVAL; /* * The sum of our children's runtime should not exceed our own. */ list_for_each_entry_rcu(child, &tg->children, siblings) { period = ktime_to_ns(child->rt_bandwidth.rt_period); runtime = child->rt_bandwidth.rt_runtime; if (child == d->tg) { period = d->rt_period; runtime = d->rt_runtime; } sum += to_ratio(period, runtime); } if (sum > total) return -EINVAL; return 0; } static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime) { struct rt_schedulable_data data = { .tg = tg, .rt_period = period, .rt_runtime = runtime, }; return walk_tg_tree(tg_schedulable, tg_nop, &data); } static int tg_set_bandwidth(struct task_group *tg, u64 rt_period, u64 rt_runtime) { int i, err = 0; mutex_lock(&rt_constraints_mutex); read_lock(&tasklist_lock); err = __rt_schedulable(tg, rt_period, rt_runtime); if (err) goto unlock; raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock); tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period); tg->rt_bandwidth.rt_runtime = rt_runtime; for_each_possible_cpu(i) { struct rt_rq *rt_rq = tg->rt_rq[i]; raw_spin_lock(&rt_rq->rt_runtime_lock); rt_rq->rt_runtime = rt_runtime; raw_spin_unlock(&rt_rq->rt_runtime_lock); } raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock); unlock: read_unlock(&tasklist_lock); mutex_unlock(&rt_constraints_mutex); return err; } int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) { u64 rt_runtime, rt_period; rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period); rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC; if (rt_runtime_us < 0) rt_runtime = RUNTIME_INF; return tg_set_bandwidth(tg, rt_period, rt_runtime); } long sched_group_rt_runtime(struct task_group *tg) { u64 rt_runtime_us; if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF) return -1; rt_runtime_us = tg->rt_bandwidth.rt_runtime; do_div(rt_runtime_us, NSEC_PER_USEC); return rt_runtime_us; } int sched_group_set_rt_period(struct task_group *tg, long rt_period_us) { u64 rt_runtime, rt_period; rt_period = (u64)rt_period_us * NSEC_PER_USEC; rt_runtime = tg->rt_bandwidth.rt_runtime; if (rt_period == 0) return -EINVAL; return tg_set_bandwidth(tg, rt_period, rt_runtime); } long sched_group_rt_period(struct task_group *tg) { u64 rt_period_us; rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period); do_div(rt_period_us, NSEC_PER_USEC); return rt_period_us; } static int sched_rt_global_constraints(void) { u64 runtime, period; int ret = 0; if (sysctl_sched_rt_period <= 0) return -EINVAL; runtime = global_rt_runtime(); period = global_rt_period(); /* * Sanity check on the sysctl variables. */ if (runtime > period && runtime != RUNTIME_INF) return -EINVAL; mutex_lock(&rt_constraints_mutex); read_lock(&tasklist_lock); ret = __rt_schedulable(NULL, 0, 0); read_unlock(&tasklist_lock); mutex_unlock(&rt_constraints_mutex); return ret; } int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk) { /* Don't accept realtime tasks when there is no way for them to run */ if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0) return 0; return 1; } #else /* !CONFIG_RT_GROUP_SCHED */ static int sched_rt_global_constraints(void) { unsigned long flags; int i; if (sysctl_sched_rt_period <= 0) return -EINVAL; /* * There's always some RT tasks in the root group * -- migration, kstopmachine etc.. */ if (sysctl_sched_rt_runtime == 0) return -EBUSY; raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags); for_each_possible_cpu(i) { struct rt_rq *rt_rq = &cpu_rq(i)->rt; raw_spin_lock(&rt_rq->rt_runtime_lock); rt_rq->rt_runtime = global_rt_runtime(); raw_spin_unlock(&rt_rq->rt_runtime_lock); } raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags); return 0; } #endif /* CONFIG_RT_GROUP_SCHED */ int sched_rt_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { int ret; int old_period, old_runtime; static DEFINE_MUTEX(mutex); mutex_lock(&mutex); old_period = sysctl_sched_rt_period; old_runtime = sysctl_sched_rt_runtime; ret = proc_dointvec(table, write, buffer, lenp, ppos); if (!ret && write) { ret = sched_rt_global_constraints(); if (ret) { sysctl_sched_rt_period = old_period; sysctl_sched_rt_runtime = old_runtime; } else { def_rt_bandwidth.rt_runtime = global_rt_runtime(); def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period()); } } mutex_unlock(&mutex); return ret; } #ifdef CONFIG_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, *parent; if (!cgrp->parent) { /* This is early initialization for the top cgroup */ return &init_task_group.css; } parent = cgroup_tg(cgrp->parent); tg = sched_create_group(parent); if (IS_ERR(tg)) return ERR_PTR(-ENOMEM); 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_task(struct cgroup *cgrp, struct task_struct *tsk) { #ifdef CONFIG_RT_GROUP_SCHED if (!sched_rt_can_attach(cgroup_tg(cgrp), tsk)) return -EINVAL; #else /* We don't support RT-tasks being in separate groups */ if (tsk->sched_class != &fair_sched_class) return -EINVAL; #endif return 0; } static int cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, struct task_struct *tsk, bool threadgroup) { int retval = cpu_cgroup_can_attach_task(cgrp, tsk); if (retval) return retval; if (threadgroup) { struct task_struct *c; rcu_read_lock(); list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) { retval = cpu_cgroup_can_attach_task(cgrp, c); if (retval) { rcu_read_unlock(); return retval; } } rcu_read_unlock(); } return 0; } static void cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, struct cgroup *old_cont, struct task_struct *tsk, bool threadgroup) { sched_move_task(tsk); if (threadgroup) { struct task_struct *c; rcu_read_lock(); list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) { sched_move_task(c); } rcu_read_unlock(); } } #ifdef CONFIG_FAIR_GROUP_SCHED static int cpu_shares_write_u64(struct cgroup *cgrp, struct cftype *cftype, u64 shareval) { return sched_group_set_shares(cgroup_tg(cgrp), shareval); } static u64 cpu_shares_read_u64(struct cgroup *cgrp, struct cftype *cft) { struct task_group *tg = cgroup_tg(cgrp); return (u64) tg->shares; } #endif /* CONFIG_FAIR_GROUP_SCHED */ #ifdef CONFIG_RT_GROUP_SCHED static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft, s64 val) { return sched_group_set_rt_runtime(cgroup_tg(cgrp), val); } static s64 cpu_rt_runtime_read(struct cgroup *cgrp, struct cftype *cft) { return sched_group_rt_runtime(cgroup_tg(cgrp)); } static int cpu_rt_period_write_uint(struct cgroup *cgrp, struct cftype *cftype, u64 rt_period_us) { return sched_group_set_rt_period(cgroup_tg(cgrp), rt_period_us); } static u64 cpu_rt_period_read_uint(struct cgroup *cgrp, struct cftype *cft) { return sched_group_rt_period(cgroup_tg(cgrp)); } #endif /* CONFIG_RT_GROUP_SCHED */ static struct cftype cpu_files[] = { #ifdef CONFIG_FAIR_GROUP_SCHED { .name = "shares", .read_u64 = cpu_shares_read_u64, .write_u64 = cpu_shares_write_u64, }, #endif #ifdef CONFIG_RT_GROUP_SCHED { .name = "rt_runtime_us", .read_s64 = cpu_rt_runtime_read, .write_s64 = cpu_rt_runtime_write, }, { .name = "rt_period_us", .read_u64 = cpu_rt_period_read_uint, .write_u64 = cpu_rt_period_write_uint, }, #endif }; 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_CGROUP_SCHED */ #ifdef CONFIG_CGROUP_CPUACCT /* * CPU accounting code for task groups. * * Based on the work by Paul Menage (menage@google.com) and Balbir Singh * (balbir@in.ibm.com). */ /* track cpu usage of a group of tasks and its child groups */ struct cpuacct { struct cgroup_subsys_state css; /* cpuusage holds pointer to a u64-type object on every cpu */ u64 __percpu *cpuusage; struct percpu_counter cpustat[CPUACCT_STAT_NSTATS]; struct cpuacct *parent; }; struct cgroup_subsys cpuacct_subsys; /* return cpu accounting group corresponding to this container */ static inline struct cpuacct *cgroup_ca(struct cgroup *cgrp) { return container_of(cgroup_subsys_state(cgrp, cpuacct_subsys_id), struct cpuacct, css); } /* return cpu accounting group to which this task belongs */ static inline struct cpuacct *task_ca(struct task_struct *tsk) { return container_of(task_subsys_state(tsk, cpuacct_subsys_id), struct cpuacct, css); } /* create a new cpu accounting group */ static struct cgroup_subsys_state *cpuacct_create( struct cgroup_subsys *ss, struct cgroup *cgrp) { struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL); int i; if (!ca) goto out; ca->cpuusage = alloc_percpu(u64); if (!ca->cpuusage) goto out_free_ca; for (i = 0; i < CPUACCT_STAT_NSTATS; i++) if (percpu_counter_init(&ca->cpustat[i], 0)) goto out_free_counters; if (cgrp->parent) ca->parent = cgroup_ca(cgrp->parent); return &ca->css; out_free_counters: while (--i >= 0) percpu_counter_destroy(&ca->cpustat[i]); free_percpu(ca->cpuusage); out_free_ca: kfree(ca); out: return ERR_PTR(-ENOMEM); } /* destroy an existing cpu accounting group */ static void cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp) { struct cpuacct *ca = cgroup_ca(cgrp); int i; for (i = 0; i < CPUACCT_STAT_NSTATS; i++) percpu_counter_destroy(&ca->cpustat[i]); free_percpu(ca->cpuusage); kfree(ca); } static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu) { u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); u64 data; #ifndef CONFIG_64BIT /* * Take rq->lock to make 64-bit read safe on 32-bit platforms. */ raw_spin_lock_irq(&cpu_rq(cpu)->lock); data = *cpuusage; raw_spin_unlock_irq(&cpu_rq(cpu)->lock); #else data = *cpuusage; #endif return data; } static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val) { u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); #ifndef CONFIG_64BIT /* * Take rq->lock to make 64-bit write safe on 32-bit platforms. */ raw_spin_lock_irq(&cpu_rq(cpu)->lock); *cpuusage = val; raw_spin_unlock_irq(&cpu_rq(cpu)->lock); #else *cpuusage = val; #endif } /* return total cpu usage (in nanoseconds) of a group */ static u64 cpuusage_read(struct cgroup *cgrp, struct cftype *cft) { struct cpuacct *ca = cgroup_ca(cgrp); u64 totalcpuusage = 0; int i; for_each_present_cpu(i) totalcpuusage += cpuacct_cpuusage_read(ca, i); return totalcpuusage; } static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype, u64 reset) { struct cpuacct *ca = cgroup_ca(cgrp); int err = 0; int i; if (reset) { err = -EINVAL; goto out; } for_each_present_cpu(i) cpuacct_cpuusage_write(ca, i, 0); out: return err; } static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft, struct seq_file *m) { struct cpuacct *ca = cgroup_ca(cgroup); u64 percpu; int i; for_each_present_cpu(i) { percpu = cpuacct_cpuusage_read(ca, i); seq_printf(m, "%llu ", (unsigned long long) percpu); } seq_printf(m, "\n"); return 0; } static const char *cpuacct_stat_desc[] = { [CPUACCT_STAT_USER] = "user", [CPUACCT_STAT_SYSTEM] = "system", }; static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft, struct cgroup_map_cb *cb) { struct cpuacct *ca = cgroup_ca(cgrp); int i; for (i = 0; i < CPUACCT_STAT_NSTATS; i++) { s64 val = percpu_counter_read(&ca->cpustat[i]); val = cputime64_to_clock_t(val); cb->fill(cb, cpuacct_stat_desc[i], val); } return 0; } static struct cftype files[] = { { .name = "usage", .read_u64 = cpuusage_read, .write_u64 = cpuusage_write, }, { .name = "usage_percpu", .read_seq_string = cpuacct_percpu_seq_read, }, { .name = "stat", .read_map = cpuacct_stats_show, }, }; static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp) { return cgroup_add_files(cgrp, ss, files, ARRAY_SIZE(files)); } /* * charge this task's execution time to its accounting group. * * called with rq->lock held. */ static void cpuacct_charge(struct task_struct *tsk, u64 cputime) { struct cpuacct *ca; int cpu; if (unlikely(!cpuacct_subsys.active)) return; cpu = task_cpu(tsk); rcu_read_lock(); ca = task_ca(tsk); for (; ca; ca = ca->parent) { u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); *cpuusage += cputime; } rcu_read_unlock(); } /* * When CONFIG_VIRT_CPU_ACCOUNTING is enabled one jiffy can be very large * in cputime_t units. As a result, cpuacct_update_stats calls * percpu_counter_add with values large enough to always overflow the * per cpu batch limit causing bad SMP scalability. * * To fix this we scale percpu_counter_batch by cputime_one_jiffy so we * batch the same amount of time with CONFIG_VIRT_CPU_ACCOUNTING disabled * and enabled. We cap it at INT_MAX which is the largest allowed batch value. */ #ifdef CONFIG_SMP #define CPUACCT_BATCH \ min_t(long, percpu_counter_batch * cputime_one_jiffy, INT_MAX) #else #define CPUACCT_BATCH 0 #endif /* * Charge the system/user time to the task's accounting group. */ static void cpuacct_update_stats(struct task_struct *tsk, enum cpuacct_stat_index idx, cputime_t val) { struct cpuacct *ca; int batch = CPUACCT_BATCH; if (unlikely(!cpuacct_subsys.active)) return; rcu_read_lock(); ca = task_ca(tsk); do { __percpu_counter_add(&ca->cpustat[idx], val, batch); ca = ca->parent; } while (ca); rcu_read_unlock(); } struct cgroup_subsys cpuacct_subsys = { .name = "cpuacct", .create = cpuacct_create, .destroy = cpuacct_destroy, .populate = cpuacct_populate, .subsys_id = cpuacct_subsys_id, }; #endif /* CONFIG_CGROUP_CPUACCT */ #ifndef CONFIG_SMP void synchronize_sched_expedited(void) { barrier(); } EXPORT_SYMBOL_GPL(synchronize_sched_expedited); #else /* #ifndef CONFIG_SMP */ static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0); static int synchronize_sched_expedited_cpu_stop(void *data) { /* * There must be a full memory barrier on each affected CPU * between the time that try_stop_cpus() is called and the * time that it returns. * * In the current initial implementation of cpu_stop, the * above condition is already met when the control reaches * this point and the following smp_mb() is not strictly * necessary. Do smp_mb() anyway for documentation and * robustness against future implementation changes. */ smp_mb(); /* See above comment block. */ return 0; } /* * Wait for an rcu-sched grace period to elapse, but use "big hammer" * approach to force grace period to end quickly. This consumes * significant time on all CPUs, and is thus not recommended for * any sort of common-case code. * * Note that it is illegal to call this function while holding any * lock that is acquired by a CPU-hotplug notifier. Failing to * observe this restriction will result in deadlock. */ void synchronize_sched_expedited(void) { int snap, trycount = 0; smp_mb(); /* ensure prior mod happens before capturing snap. */ snap = atomic_read(&synchronize_sched_expedited_count) + 1; get_online_cpus(); while (try_stop_cpus(cpu_online_mask, synchronize_sched_expedited_cpu_stop, NULL) == -EAGAIN) { put_online_cpus(); if (trycount++ < 10) udelay(trycount * num_online_cpus()); else { synchronize_sched(); return; } if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) { smp_mb(); /* ensure test happens before caller kfree */ return; } get_online_cpus(); } atomic_inc(&synchronize_sched_expedited_count); smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */ put_online_cpus(); } EXPORT_SYMBOL_GPL(synchronize_sched_expedited); #endif /* #else #ifndef CONFIG_SMP */