diff options
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/hrtimer.c | 53 | ||||
| -rw-r--r-- | kernel/time/ntp.c | 2 | ||||
| -rw-r--r-- | kernel/time/tick-sched.c | 250 | ||||
| -rw-r--r-- | kernel/time/tick-sched.h | 18 |
4 files changed, 241 insertions, 82 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 9b082ce86325..eda1210ce50f 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -480,6 +480,7 @@ __next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active) while ((base = __next_base((cpu_base), &(active)))) static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base, + const struct hrtimer *exclude, unsigned int active, ktime_t expires_next) { @@ -492,9 +493,22 @@ static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base, next = timerqueue_getnext(&base->active); timer = container_of(next, struct hrtimer, node); + if (timer == exclude) { + /* Get to the next timer in the queue. */ + next = timerqueue_iterate_next(next); + if (!next) + continue; + + timer = container_of(next, struct hrtimer, node); + } expires = ktime_sub(hrtimer_get_expires(timer), base->offset); if (expires < expires_next) { expires_next = expires; + + /* Skip cpu_base update if a timer is being excluded. */ + if (exclude) + continue; + if (timer->is_soft) cpu_base->softirq_next_timer = timer; else @@ -538,7 +552,8 @@ __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_ if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) { active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT; cpu_base->softirq_next_timer = NULL; - expires_next = __hrtimer_next_event_base(cpu_base, active, KTIME_MAX); + expires_next = __hrtimer_next_event_base(cpu_base, NULL, + active, KTIME_MAX); next_timer = cpu_base->softirq_next_timer; } @@ -546,7 +561,8 @@ __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_ if (active_mask & HRTIMER_ACTIVE_HARD) { active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD; cpu_base->next_timer = next_timer; - expires_next = __hrtimer_next_event_base(cpu_base, active, expires_next); + expires_next = __hrtimer_next_event_base(cpu_base, NULL, active, + expires_next); } return expires_next; @@ -1190,6 +1206,39 @@ u64 hrtimer_get_next_event(void) return expires; } + +/** + * hrtimer_next_event_without - time until next expiry event w/o one timer + * @exclude: timer to exclude + * + * Returns the next expiry time over all timers except for the @exclude one or + * KTIME_MAX if none of them is pending. + */ +u64 hrtimer_next_event_without(const struct hrtimer *exclude) +{ + struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases); + u64 expires = KTIME_MAX; + unsigned long flags; + + raw_spin_lock_irqsave(&cpu_base->lock, flags); + + if (__hrtimer_hres_active(cpu_base)) { + unsigned int active; + + if (!cpu_base->softirq_activated) { + active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT; + expires = __hrtimer_next_event_base(cpu_base, exclude, + active, KTIME_MAX); + } + active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD; + expires = __hrtimer_next_event_base(cpu_base, exclude, active, + expires); + } + + raw_spin_unlock_irqrestore(&cpu_base->lock, flags); + + return expires; +} #endif static inline int hrtimer_clockid_to_base(clockid_t clock_id) diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 8d70da1b9a0d..a09ded765f6c 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -31,7 +31,7 @@ /* USER_HZ period (usecs): */ -unsigned long tick_usec = TICK_USEC; +unsigned long tick_usec = USER_TICK_USEC; /* SHIFTED_HZ period (nsecs): */ unsigned long tick_nsec; diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index f3ab08caa2c3..646645e981f9 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -122,8 +122,7 @@ static ktime_t tick_init_jiffy_update(void) return period; } - -static void tick_sched_do_timer(ktime_t now) +static void tick_sched_do_timer(struct tick_sched *ts, ktime_t now) { int cpu = smp_processor_id(); @@ -143,6 +142,9 @@ static void tick_sched_do_timer(ktime_t now) /* Check, if the jiffies need an update */ if (tick_do_timer_cpu == cpu) tick_do_update_jiffies64(now); + + if (ts->inidle) + ts->got_idle_tick = 1; } static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) @@ -474,7 +476,9 @@ __setup("nohz=", setup_tick_nohz); bool tick_nohz_tick_stopped(void) { - return __this_cpu_read(tick_cpu_sched.tick_stopped); + struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); + + return ts->tick_stopped; } bool tick_nohz_tick_stopped_cpu(int cpu) @@ -537,14 +541,11 @@ static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now) sched_clock_idle_wakeup_event(); } -static ktime_t tick_nohz_start_idle(struct tick_sched *ts) +static void tick_nohz_start_idle(struct tick_sched *ts) { - ktime_t now = ktime_get(); - - ts->idle_entrytime = now; + ts->idle_entrytime = ktime_get(); ts->idle_active = 1; sched_clock_idle_sleep_event(); - return now; } /** @@ -653,13 +654,10 @@ static inline bool local_timer_softirq_pending(void) return local_softirq_pending() & TIMER_SOFTIRQ; } -static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, - ktime_t now, int cpu) +static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu) { - struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); u64 basemono, next_tick, next_tmr, next_rcu, delta, expires; unsigned long seq, basejiff; - ktime_t tick; /* Read jiffies and the time when jiffies were updated last */ do { @@ -668,6 +666,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, basejiff = jiffies; } while (read_seqretry(&jiffies_lock, seq)); ts->last_jiffies = basejiff; + ts->timer_expires_base = basemono; /* * Keep the periodic tick, when RCU, architecture or irq_work @@ -712,47 +711,63 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, * next period, so no point in stopping it either, bail. */ if (!ts->tick_stopped) { - tick = 0; + ts->timer_expires = 0; goto out; } } /* + * If this CPU is the one which had the do_timer() duty last, we limit + * the sleep time to the timekeeping max_deferment value. + * Otherwise we can sleep as long as we want. + */ + delta = timekeeping_max_deferment(); + if (cpu != tick_do_timer_cpu && + (tick_do_timer_cpu != TICK_DO_TIMER_NONE || !ts->do_timer_last)) + delta = KTIME_MAX; + + /* Calculate the next expiry time */ + if (delta < (KTIME_MAX - basemono)) + expires = basemono + delta; + else + expires = KTIME_MAX; + + ts->timer_expires = min_t(u64, expires, next_tick); + +out: + return ts->timer_expires; +} + +static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu) +{ + struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); + u64 basemono = ts->timer_expires_base; + u64 expires = ts->timer_expires; + ktime_t tick = expires; + + /* Make sure we won't be trying to stop it twice in a row. */ + ts->timer_expires_base = 0; + + /* * If this CPU is the one which updates jiffies, then give up * the assignment and let it be taken by the CPU which runs * the tick timer next, which might be this CPU as well. If we * don't drop this here the jiffies might be stale and * do_timer() never invoked. Keep track of the fact that it - * was the one which had the do_timer() duty last. If this CPU - * is the one which had the do_timer() duty last, we limit the - * sleep time to the timekeeping max_deferment value. - * Otherwise we can sleep as long as we want. + * was the one which had the do_timer() duty last. */ - delta = timekeeping_max_deferment(); if (cpu == tick_do_timer_cpu) { tick_do_timer_cpu = TICK_DO_TIMER_NONE; ts->do_timer_last = 1; } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { - delta = KTIME_MAX; ts->do_timer_last = 0; - } else if (!ts->do_timer_last) { - delta = KTIME_MAX; } - /* Calculate the next expiry time */ - if (delta < (KTIME_MAX - basemono)) - expires = basemono + delta; - else - expires = KTIME_MAX; - - expires = min_t(u64, expires, next_tick); - tick = expires; - /* Skip reprogram of event if its not changed */ if (ts->tick_stopped && (expires == ts->next_tick)) { /* Sanity check: make sure clockevent is actually programmed */ if (tick == KTIME_MAX || ts->next_tick == hrtimer_get_expires(&ts->sched_timer)) - goto out; + return; WARN_ON_ONCE(1); printk_once("basemono: %llu ts->next_tick: %llu dev->next_event: %llu timer->active: %d timer->expires: %llu\n", @@ -786,7 +801,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, if (unlikely(expires == KTIME_MAX)) { if (ts->nohz_mode == NOHZ_MODE_HIGHRES) hrtimer_cancel(&ts->sched_timer); - goto out; + return; } hrtimer_set_expires(&ts->sched_timer, tick); @@ -795,15 +810,23 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED); else tick_program_event(tick, 1); -out: - /* - * Update the estimated sleep length until the next timer - * (not only the tick). - */ - ts->sleep_length = ktime_sub(dev->next_event, now); - return tick; } +static void tick_nohz_retain_tick(struct tick_sched *ts) +{ + ts->timer_expires_base = 0; +} + +#ifdef CONFIG_NO_HZ_FULL +static void tick_nohz_stop_sched_tick(struct tick_sched *ts, int cpu) +{ + if (tick_nohz_next_event(ts, cpu)) + tick_nohz_stop_tick(ts, cpu); + else + tick_nohz_retain_tick(ts); +} +#endif /* CONFIG_NO_HZ_FULL */ + static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now) { /* Update jiffies first */ @@ -839,7 +862,7 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts) return; if (can_stop_full_tick(cpu, ts)) - tick_nohz_stop_sched_tick(ts, ktime_get(), cpu); + tick_nohz_stop_sched_tick(ts, cpu); else if (ts->tick_stopped) tick_nohz_restart_sched_tick(ts, ktime_get()); #endif @@ -865,10 +888,8 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) return false; } - if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) { - ts->sleep_length = NSEC_PER_SEC / HZ; + if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) return false; - } if (need_resched()) return false; @@ -903,42 +924,65 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) return true; } -static void __tick_nohz_idle_enter(struct tick_sched *ts) +static void __tick_nohz_idle_stop_tick(struct tick_sched *ts) { - ktime_t now, expires; + ktime_t expires; int cpu = smp_processor_id(); - now = tick_nohz_start_idle(ts); + /* + * If tick_nohz_get_sleep_length() ran tick_nohz_next_event(), the + * tick timer expiration time is known already. + */ + if (ts->timer_expires_base) + expires = ts->timer_expires; + else if (can_stop_idle_tick(cpu, ts)) + expires = tick_nohz_next_event(ts, cpu); + else + return; + + ts->idle_calls++; - if (can_stop_idle_tick(cpu, ts)) { + if (expires > 0LL) { int was_stopped = ts->tick_stopped; - ts->idle_calls++; + tick_nohz_stop_tick(ts, cpu); - expires = tick_nohz_stop_sched_tick(ts, now, cpu); - if (expires > 0LL) { - ts->idle_sleeps++; - ts->idle_expires = expires; - } + ts->idle_sleeps++; + ts->idle_expires = expires; if (!was_stopped && ts->tick_stopped) { ts->idle_jiffies = ts->last_jiffies; nohz_balance_enter_idle(cpu); } + } else { + tick_nohz_retain_tick(ts); } } /** - * tick_nohz_idle_enter - stop the idle tick from the idle task + * tick_nohz_idle_stop_tick - stop the idle tick from the idle task * * When the next event is more than a tick into the future, stop the idle tick - * Called when we start the idle loop. - * - * The arch is responsible of calling: + */ +void tick_nohz_idle_stop_tick(void) +{ + __tick_nohz_idle_stop_tick(this_cpu_ptr(&tick_cpu_sched)); +} + +void tick_nohz_idle_retain_tick(void) +{ + tick_nohz_retain_tick(this_cpu_ptr(&tick_cpu_sched)); + /* + * Undo the effect of get_next_timer_interrupt() called from + * tick_nohz_next_event(). + */ + timer_clear_idle(); +} + +/** + * tick_nohz_idle_enter - prepare for entering idle on the current CPU * - * - rcu_idle_enter() after its last use of RCU before the CPU is put - * to sleep. - * - rcu_idle_exit() before the first use of RCU after the CPU is woken up. + * Called when we start the idle loop. */ void tick_nohz_idle_enter(void) { @@ -949,8 +993,11 @@ void tick_nohz_idle_enter(void) local_irq_disable(); ts = this_cpu_ptr(&tick_cpu_sched); + + WARN_ON_ONCE(ts->timer_expires_base); + ts->inidle = 1; - __tick_nohz_idle_enter(ts); + tick_nohz_start_idle(ts); local_irq_enable(); } @@ -968,21 +1015,62 @@ void tick_nohz_irq_exit(void) struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); if (ts->inidle) - __tick_nohz_idle_enter(ts); + tick_nohz_start_idle(ts); else tick_nohz_full_update_tick(ts); } /** - * tick_nohz_get_sleep_length - return the length of the current sleep + * tick_nohz_idle_got_tick - Check whether or not the tick handler has run + */ +bool tick_nohz_idle_got_tick(void) +{ + struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); + + if (ts->got_idle_tick) { + ts->got_idle_tick = 0; + return true; + } + return false; +} + +/** + * tick_nohz_get_sleep_length - return the expected length of the current sleep + * @delta_next: duration until the next event if the tick cannot be stopped * * Called from power state control code with interrupts disabled */ -ktime_t tick_nohz_get_sleep_length(void) +ktime_t tick_nohz_get_sleep_length(ktime_t *delta_next) { + struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); + int cpu = smp_processor_id(); + /* + * The idle entry time is expected to be a sufficient approximation of + * the current time at this point. + */ + ktime_t now = ts->idle_entrytime; + ktime_t next_event; + + WARN_ON_ONCE(!ts->inidle); + + *delta_next = ktime_sub(dev->next_event, now); + + if (!can_stop_idle_tick(cpu, ts)) + return *delta_next; + + next_event = tick_nohz_next_event(ts, cpu); + if (!next_event) + return *delta_next; + + /* + * If the next highres timer to expire is earlier than next_event, the + * idle governor needs to know that. + */ + next_event = min_t(u64, next_event, + hrtimer_next_event_without(&ts->sched_timer)); - return ts->sleep_length; + return ktime_sub(next_event, now); } /** @@ -1031,6 +1119,20 @@ static void tick_nohz_account_idle_ticks(struct tick_sched *ts) #endif } +static void __tick_nohz_idle_restart_tick(struct tick_sched *ts, ktime_t now) +{ + tick_nohz_restart_sched_tick(ts, now); + tick_nohz_account_idle_ticks(ts); +} + +void tick_nohz_idle_restart_tick(void) +{ + struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); + + if (ts->tick_stopped) + __tick_nohz_idle_restart_tick(ts, ktime_get()); +} + /** * tick_nohz_idle_exit - restart the idle tick from the idle task * @@ -1041,24 +1143,26 @@ static void tick_nohz_account_idle_ticks(struct tick_sched *ts) void tick_nohz_idle_exit(void) { struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); + bool idle_active, tick_stopped; ktime_t now; local_irq_disable(); WARN_ON_ONCE(!ts->inidle); + WARN_ON_ONCE(ts->timer_expires_base); ts->inidle = 0; + idle_active = ts->idle_active; + tick_stopped = ts->tick_stopped; - if (ts->idle_active || ts->tick_stopped) + if (idle_active || tick_stopped) now = ktime_get(); - if (ts->idle_active) + if (idle_active) tick_nohz_stop_idle(ts, now); - if (ts->tick_stopped) { - tick_nohz_restart_sched_tick(ts, now); - tick_nohz_account_idle_ticks(ts); - } + if (tick_stopped) + __tick_nohz_idle_restart_tick(ts, now); local_irq_enable(); } @@ -1074,7 +1178,7 @@ static void tick_nohz_handler(struct clock_event_device *dev) dev->next_event = KTIME_MAX; - tick_sched_do_timer(now); + tick_sched_do_timer(ts, now); tick_sched_handle(ts, regs); /* No need to reprogram if we are running tickless */ @@ -1169,7 +1273,7 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) struct pt_regs *regs = get_irq_regs(); ktime_t now = ktime_get(); - tick_sched_do_timer(now); + tick_sched_do_timer(ts, now); /* * Do not call, when we are not in irq context and have diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h index 954b43dbf21c..6de959a854b2 100644 --- a/kernel/time/tick-sched.h +++ b/kernel/time/tick-sched.h @@ -38,31 +38,37 @@ enum tick_nohz_mode { * @idle_exittime: Time when the idle state was left * @idle_sleeptime: Sum of the time slept in idle with sched tick stopped * @iowait_sleeptime: Sum of the time slept in idle with sched tick stopped, with IO outstanding - * @sleep_length: Duration of the current idle sleep + * @timer_expires: Anticipated timer expiration time (in case sched tick is stopped) + * @timer_expires_base: Base time clock monotonic for @timer_expires * @do_timer_lst: CPU was the last one doing do_timer before going idle + * @got_idle_tick: Tick timer function has run with @inidle set */ struct tick_sched { struct hrtimer sched_timer; unsigned long check_clocks; enum tick_nohz_mode nohz_mode; + + unsigned int inidle : 1; + unsigned int tick_stopped : 1; + unsigned int idle_active : 1; + unsigned int do_timer_last : 1; + unsigned int got_idle_tick : 1; + ktime_t last_tick; ktime_t next_tick; - int inidle; - int tick_stopped; unsigned long idle_jiffies; unsigned long idle_calls; unsigned long idle_sleeps; - int idle_active; ktime_t idle_entrytime; ktime_t idle_waketime; ktime_t idle_exittime; ktime_t idle_sleeptime; ktime_t iowait_sleeptime; - ktime_t sleep_length; unsigned long last_jiffies; + u64 timer_expires; + u64 timer_expires_base; u64 next_timer; ktime_t idle_expires; - int do_timer_last; atomic_t tick_dep_mask; }; |