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author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-12-01 14:39:51 +0100 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-12-01 14:39:51 +0100 |
commit | 4e28ec3d5fe0b994fe87b2406d75d9c351ef4940 (patch) | |
tree | af6fbb01ca736ff7e9f57bed685508bd74fc7cac /kernel/sched | |
parent | a2c1bc645e87346150516b3abf1933ed29d0f48b (diff) | |
parent | 6af33995318fdfb4914fb1c5e67450fdb3d32084 (diff) | |
download | linux-4e28ec3d5fe0b994fe87b2406d75d9c351ef4940.tar.gz linux-4e28ec3d5fe0b994fe87b2406d75d9c351ef4940.tar.bz2 linux-4e28ec3d5fe0b994fe87b2406d75d9c351ef4940.zip |
Merge back earlier cpuidle material for v4.10.
Diffstat (limited to 'kernel/sched')
-rw-r--r-- | kernel/sched/core.c | 1 | ||||
-rw-r--r-- | kernel/sched/idle.c | 175 |
2 files changed, 110 insertions, 66 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 154fd689fe02..c95fbcd9fe1f 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5279,6 +5279,7 @@ void init_idle(struct task_struct *idle, int cpu) __sched_fork(0, idle); idle->state = TASK_RUNNING; idle->se.exec_start = sched_clock(); + idle->flags |= PF_IDLE; kasan_unpoison_task_stack(idle); diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 1d8718d5300d..6a4bae0a649d 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -164,11 +164,14 @@ static void cpuidle_idle_call(void) * timekeeping to prevent timer interrupts from kicking us out of idle * until a proper wakeup interrupt happens. */ - if (idle_should_freeze()) { - entered_state = cpuidle_enter_freeze(drv, dev); - if (entered_state > 0) { - local_irq_enable(); - goto exit_idle; + + if (idle_should_freeze() || dev->use_deepest_state) { + if (idle_should_freeze()) { + entered_state = cpuidle_enter_freeze(drv, dev); + if (entered_state > 0) { + local_irq_enable(); + goto exit_idle; + } } next_state = cpuidle_find_deepest_state(drv, dev); @@ -202,76 +205,65 @@ exit_idle: * * Called with polling cleared. */ -static void cpu_idle_loop(void) +static void do_idle(void) { - int cpu = smp_processor_id(); - - while (1) { - /* - * If the arch has a polling bit, we maintain an invariant: - * - * Our polling bit is clear if we're not scheduled (i.e. if - * rq->curr != rq->idle). This means that, if rq->idle has - * the polling bit set, then setting need_resched is - * guaranteed to cause the cpu to reschedule. - */ - - __current_set_polling(); - quiet_vmstat(); - tick_nohz_idle_enter(); + /* + * If the arch has a polling bit, we maintain an invariant: + * + * Our polling bit is clear if we're not scheduled (i.e. if rq->curr != + * rq->idle). This means that, if rq->idle has the polling bit set, + * then setting need_resched is guaranteed to cause the CPU to + * reschedule. + */ - while (!need_resched()) { - check_pgt_cache(); - rmb(); + __current_set_polling(); + tick_nohz_idle_enter(); - if (cpu_is_offline(cpu)) { - cpuhp_report_idle_dead(); - arch_cpu_idle_dead(); - } + while (!need_resched()) { + check_pgt_cache(); + rmb(); - local_irq_disable(); - arch_cpu_idle_enter(); - - /* - * In poll mode we reenable interrupts and spin. - * - * Also if we detected in the wakeup from idle - * path that the tick broadcast device expired - * for us, we don't want to go deep idle as we - * know that the IPI is going to arrive right - * away - */ - if (cpu_idle_force_poll || tick_check_broadcast_expired()) - cpu_idle_poll(); - else - cpuidle_idle_call(); - - arch_cpu_idle_exit(); + if (cpu_is_offline(smp_processor_id())) { + cpuhp_report_idle_dead(); + arch_cpu_idle_dead(); } - /* - * Since we fell out of the loop above, we know - * TIF_NEED_RESCHED must be set, propagate it into - * PREEMPT_NEED_RESCHED. - * - * This is required because for polling idle loops we will - * not have had an IPI to fold the state for us. - */ - preempt_set_need_resched(); - tick_nohz_idle_exit(); - __current_clr_polling(); + local_irq_disable(); + arch_cpu_idle_enter(); /* - * We promise to call sched_ttwu_pending and reschedule - * if need_resched is set while polling is set. That - * means that clearing polling needs to be visible - * before doing these things. + * In poll mode we reenable interrupts and spin. Also if we + * detected in the wakeup from idle path that the tick + * broadcast device expired for us, we don't want to go deep + * idle as we know that the IPI is going to arrive right away. */ - smp_mb__after_atomic(); - - sched_ttwu_pending(); - schedule_preempt_disabled(); + if (cpu_idle_force_poll || tick_check_broadcast_expired()) + cpu_idle_poll(); + else + cpuidle_idle_call(); + arch_cpu_idle_exit(); } + + /* + * Since we fell out of the loop above, we know TIF_NEED_RESCHED must + * be set, propagate it into PREEMPT_NEED_RESCHED. + * + * This is required because for polling idle loops we will not have had + * an IPI to fold the state for us. + */ + preempt_set_need_resched(); + tick_nohz_idle_exit(); + __current_clr_polling(); + + /* + * We promise to call sched_ttwu_pending() and reschedule if + * need_resched() is set while polling is set. That means that clearing + * polling needs to be visible before doing these things. + */ + smp_mb__after_atomic(); + + sched_ttwu_pending(); + schedule_preempt_disabled(); } bool cpu_in_idle(unsigned long pc) @@ -280,6 +272,56 @@ bool cpu_in_idle(unsigned long pc) pc < (unsigned long)__cpuidle_text_end; } +struct idle_timer { + struct hrtimer timer; + int done; +}; + +static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *timer) +{ + struct idle_timer *it = container_of(timer, struct idle_timer, timer); + + WRITE_ONCE(it->done, 1); + set_tsk_need_resched(current); + + return HRTIMER_NORESTART; +} + +void play_idle(unsigned long duration_ms) +{ + struct idle_timer it; + + /* + * Only FIFO tasks can disable the tick since they don't need the forced + * preemption. + */ + WARN_ON_ONCE(current->policy != SCHED_FIFO); + WARN_ON_ONCE(current->nr_cpus_allowed != 1); + WARN_ON_ONCE(!(current->flags & PF_KTHREAD)); + WARN_ON_ONCE(!(current->flags & PF_NO_SETAFFINITY)); + WARN_ON_ONCE(!duration_ms); + + rcu_sleep_check(); + preempt_disable(); + current->flags |= PF_IDLE; + cpuidle_use_deepest_state(true); + + it.done = 0; + hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + it.timer.function = idle_inject_timer_fn; + hrtimer_start(&it.timer, ms_to_ktime(duration_ms), HRTIMER_MODE_REL_PINNED); + + while (!READ_ONCE(it.done)) + do_idle(); + + cpuidle_use_deepest_state(false); + current->flags &= ~PF_IDLE; + + preempt_fold_need_resched(); + preempt_enable(); +} +EXPORT_SYMBOL_GPL(play_idle); + void cpu_startup_entry(enum cpuhp_state state) { /* @@ -299,5 +341,6 @@ void cpu_startup_entry(enum cpuhp_state state) #endif arch_cpu_idle_prepare(); cpuhp_online_idle(state); - cpu_idle_loop(); + while (1) + do_idle(); } |