diff options
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 186 |
1 files changed, 119 insertions, 67 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c94895bc5a2c..de440456f15c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5,37 +5,11 @@ * * Copyright (C) 1991-2002 Linus Torvalds */ -#include <linux/sched.h> -#include <linux/sched/clock.h> -#include <uapi/linux/sched/types.h> -#include <linux/sched/loadavg.h> -#include <linux/sched/hotplug.h> -#include <linux/wait_bit.h> -#include <linux/cpuset.h> -#include <linux/delayacct.h> -#include <linux/init_task.h> -#include <linux/context_tracking.h> -#include <linux/rcupdate_wait.h> -#include <linux/compat.h> - -#include <linux/blkdev.h> -#include <linux/kprobes.h> -#include <linux/mmu_context.h> -#include <linux/module.h> -#include <linux/nmi.h> -#include <linux/prefetch.h> -#include <linux/profile.h> -#include <linux/security.h> -#include <linux/syscalls.h> -#include <linux/sched/isolation.h> +#include "sched.h" #include <asm/switch_to.h> #include <asm/tlb.h> -#ifdef CONFIG_PARAVIRT -#include <asm/paravirt.h> -#endif -#include "sched.h" #include "../workqueue_internal.h" #include "../smpboot.h" @@ -135,7 +109,7 @@ struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf) * [L] ->on_rq * RELEASE (rq->lock) * - * If we observe the old cpu in task_rq_lock, the acquire of + * If we observe the old CPU in task_rq_lock, the acquire of * the old rq->lock will fully serialize against the stores. * * If we observe the new CPU in task_rq_lock, the acquire will @@ -333,7 +307,7 @@ void hrtick_start(struct rq *rq, u64 delay) } #endif /* CONFIG_SMP */ -static void init_rq_hrtick(struct rq *rq) +static void hrtick_rq_init(struct rq *rq) { #ifdef CONFIG_SMP rq->hrtick_csd_pending = 0; @@ -351,7 +325,7 @@ static inline void hrtick_clear(struct rq *rq) { } -static inline void init_rq_hrtick(struct rq *rq) +static inline void hrtick_rq_init(struct rq *rq) { } #endif /* CONFIG_SCHED_HRTICK */ @@ -609,7 +583,7 @@ static inline bool got_nohz_idle_kick(void) { int cpu = smp_processor_id(); - if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu))) + if (!(atomic_read(nohz_flags(cpu)) & NOHZ_KICK_MASK)) return false; if (idle_cpu(cpu) && !need_resched()) @@ -619,7 +593,7 @@ static inline bool got_nohz_idle_kick(void) * We can't run Idle Load Balance on this CPU for this time so we * cancel it and clear NOHZ_BALANCE_KICK */ - clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); + atomic_andnot(NOHZ_KICK_MASK, nohz_flags(cpu)); return false; } @@ -1457,7 +1431,7 @@ EXPORT_SYMBOL_GPL(kick_process); * * - cpu_active must be a subset of cpu_online * - * - on cpu-up we allow per-cpu kthreads on the online && !active cpu, + * - on CPU-up we allow per-CPU kthreads on the online && !active CPU, * see __set_cpus_allowed_ptr(). At this point the newly online * CPU isn't yet part of the sched domains, and balancing will not * see it. @@ -2488,17 +2462,17 @@ void wake_up_new_task(struct task_struct *p) #ifdef CONFIG_PREEMPT_NOTIFIERS -static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE; +static DEFINE_STATIC_KEY_FALSE(preempt_notifier_key); void preempt_notifier_inc(void) { - static_key_slow_inc(&preempt_notifier_key); + static_branch_inc(&preempt_notifier_key); } EXPORT_SYMBOL_GPL(preempt_notifier_inc); void preempt_notifier_dec(void) { - static_key_slow_dec(&preempt_notifier_key); + static_branch_dec(&preempt_notifier_key); } EXPORT_SYMBOL_GPL(preempt_notifier_dec); @@ -2508,7 +2482,7 @@ EXPORT_SYMBOL_GPL(preempt_notifier_dec); */ void preempt_notifier_register(struct preempt_notifier *notifier) { - if (!static_key_false(&preempt_notifier_key)) + if (!static_branch_unlikely(&preempt_notifier_key)) WARN(1, "registering preempt_notifier while notifiers disabled\n"); hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); @@ -2537,7 +2511,7 @@ static void __fire_sched_in_preempt_notifiers(struct task_struct *curr) static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) { - if (static_key_false(&preempt_notifier_key)) + if (static_branch_unlikely(&preempt_notifier_key)) __fire_sched_in_preempt_notifiers(curr); } @@ -2555,7 +2529,7 @@ static __always_inline void fire_sched_out_preempt_notifiers(struct task_struct *curr, struct task_struct *next) { - if (static_key_false(&preempt_notifier_key)) + if (static_branch_unlikely(&preempt_notifier_key)) __fire_sched_out_preempt_notifiers(curr, next); } @@ -2629,6 +2603,18 @@ static inline void finish_lock_switch(struct rq *rq) raw_spin_unlock_irq(&rq->lock); } +/* + * NOP if the arch has not defined these: + */ + +#ifndef prepare_arch_switch +# define prepare_arch_switch(next) do { } while (0) +#endif + +#ifndef finish_arch_post_lock_switch +# define finish_arch_post_lock_switch() do { } while (0) +#endif + /** * prepare_task_switch - prepare to switch tasks * @rq: the runqueue preparing to switch @@ -3037,7 +3023,7 @@ unsigned long long task_sched_runtime(struct task_struct *p) #if defined(CONFIG_64BIT) && defined(CONFIG_SMP) /* - * 64-bit doesn't need locks to atomically read a 64bit value. + * 64-bit doesn't need locks to atomically read a 64-bit value. * So we have a optimization chance when the task's delta_exec is 0. * Reading ->on_cpu is racy, but this is ok. * @@ -3096,35 +3082,99 @@ void scheduler_tick(void) rq->idle_balance = idle_cpu(cpu); trigger_load_balance(rq); #endif - rq_last_tick_reset(rq); } #ifdef CONFIG_NO_HZ_FULL -/** - * scheduler_tick_max_deferment - * - * Keep at least one tick per second when a single - * active task is running because the scheduler doesn't - * yet completely support full dynticks environment. - * - * This makes sure that uptime, CFS vruntime, load - * balancing, etc... continue to move forward, even - * with a very low granularity. - * - * Return: Maximum deferment in nanoseconds. - */ -u64 scheduler_tick_max_deferment(void) + +struct tick_work { + int cpu; + struct delayed_work work; +}; + +static struct tick_work __percpu *tick_work_cpu; + +static void sched_tick_remote(struct work_struct *work) { - struct rq *rq = this_rq(); - unsigned long next, now = READ_ONCE(jiffies); + struct delayed_work *dwork = to_delayed_work(work); + struct tick_work *twork = container_of(dwork, struct tick_work, work); + int cpu = twork->cpu; + struct rq *rq = cpu_rq(cpu); + struct rq_flags rf; - next = rq->last_sched_tick + HZ; + /* + * Handle the tick only if it appears the remote CPU is running in full + * dynticks mode. The check is racy by nature, but missing a tick or + * having one too much is no big deal because the scheduler tick updates + * statistics and checks timeslices in a time-independent way, regardless + * of when exactly it is running. + */ + if (!idle_cpu(cpu) && tick_nohz_tick_stopped_cpu(cpu)) { + struct task_struct *curr; + u64 delta; - if (time_before_eq(next, now)) - return 0; + rq_lock_irq(rq, &rf); + update_rq_clock(rq); + curr = rq->curr; + delta = rq_clock_task(rq) - curr->se.exec_start; - return jiffies_to_nsecs(next - now); + /* + * Make sure the next tick runs within a reasonable + * amount of time. + */ + WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3); + curr->sched_class->task_tick(rq, curr, 0); + rq_unlock_irq(rq, &rf); + } + + /* + * Run the remote tick once per second (1Hz). This arbitrary + * frequency is large enough to avoid overload but short enough + * to keep scheduler internal stats reasonably up to date. + */ + queue_delayed_work(system_unbound_wq, dwork, HZ); } + +static void sched_tick_start(int cpu) +{ + struct tick_work *twork; + + if (housekeeping_cpu(cpu, HK_FLAG_TICK)) + return; + + WARN_ON_ONCE(!tick_work_cpu); + + twork = per_cpu_ptr(tick_work_cpu, cpu); + twork->cpu = cpu; + INIT_DELAYED_WORK(&twork->work, sched_tick_remote); + queue_delayed_work(system_unbound_wq, &twork->work, HZ); +} + +#ifdef CONFIG_HOTPLUG_CPU +static void sched_tick_stop(int cpu) +{ + struct tick_work *twork; + + if (housekeeping_cpu(cpu, HK_FLAG_TICK)) + return; + + WARN_ON_ONCE(!tick_work_cpu); + + twork = per_cpu_ptr(tick_work_cpu, cpu); + cancel_delayed_work_sync(&twork->work); +} +#endif /* CONFIG_HOTPLUG_CPU */ + +int __init sched_tick_offload_init(void) +{ + tick_work_cpu = alloc_percpu(struct tick_work); + BUG_ON(!tick_work_cpu); + + return 0; +} + +#else /* !CONFIG_NO_HZ_FULL */ +static inline void sched_tick_start(int cpu) { } +static inline void sched_tick_stop(int cpu) { } #endif #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ @@ -5786,6 +5836,7 @@ int sched_cpu_starting(unsigned int cpu) { set_cpu_rq_start_time(cpu); sched_rq_cpu_starting(cpu); + sched_tick_start(cpu); return 0; } @@ -5797,6 +5848,7 @@ int sched_cpu_dying(unsigned int cpu) /* Handle pending wakeups and then migrate everything off */ sched_ttwu_pending(); + sched_tick_stop(cpu); rq_lock_irqsave(rq, &rf); if (rq->rd) { @@ -5809,7 +5861,7 @@ int sched_cpu_dying(unsigned int cpu) calc_load_migrate(rq); update_max_interval(); - nohz_balance_exit_idle(cpu); + nohz_balance_exit_idle(rq); hrtick_clear(rq); return 0; } @@ -6022,13 +6074,11 @@ void __init sched_init(void) rq_attach_root(rq, &def_root_domain); #ifdef CONFIG_NO_HZ_COMMON rq->last_load_update_tick = jiffies; - rq->nohz_flags = 0; -#endif -#ifdef CONFIG_NO_HZ_FULL - rq->last_sched_tick = 0; + rq->last_blocked_load_update_tick = jiffies; + atomic_set(&rq->nohz_flags, 0); #endif #endif /* CONFIG_SMP */ - init_rq_hrtick(rq); + hrtick_rq_init(rq); atomic_set(&rq->nr_iowait, 0); } @@ -7027,3 +7077,5 @@ const u32 sched_prio_to_wmult[40] = { /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717, /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, }; + +#undef CREATE_TRACE_POINTS |