From 5bb962269c29cbb878414cddf0ebdff8c5cdef0a Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Mon, 15 Oct 2012 02:03:27 +0200 Subject: [PATCH 1/3] tick: Consolidate timekeeping handling code Unify the duplicated timekeeping handling code of low and high res tick sched handlers. Signed-off-by: Frederic Weisbecker Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Peter Zijlstra --- kernel/time/tick-sched.c | 54 ++++++++++++++++++---------------------- 1 file changed, 24 insertions(+), 30 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index a402608852657..360674c485f5d 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -98,6 +98,28 @@ static ktime_t tick_init_jiffy_update(void) return period; } + +static void tick_sched_do_timer(ktime_t now) +{ + int cpu = smp_processor_id(); + +#ifdef CONFIG_NO_HZ + /* + * Check if the do_timer duty was dropped. We don't care about + * concurrency: This happens only when the cpu in charge went + * into a long sleep. If two cpus happen to assign themself to + * this duty, then the jiffies update is still serialized by + * xtime_lock. + */ + if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) + tick_do_timer_cpu = cpu; +#endif + + /* Check, if the jiffies need an update */ + if (tick_do_timer_cpu == cpu) + tick_do_update_jiffies64(now); +} + /* * NOHZ - aka dynamic tick functionality */ @@ -648,24 +670,11 @@ static void tick_nohz_handler(struct clock_event_device *dev) { struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); struct pt_regs *regs = get_irq_regs(); - int cpu = smp_processor_id(); ktime_t now = ktime_get(); dev->next_event.tv64 = KTIME_MAX; - /* - * Check if the do_timer duty was dropped. We don't care about - * concurrency: This happens only when the cpu in charge went - * into a long sleep. If two cpus happen to assign themself to - * this duty, then the jiffies update is still serialized by - * xtime_lock. - */ - if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) - tick_do_timer_cpu = cpu; - - /* Check, if the jiffies need an update */ - if (tick_do_timer_cpu == cpu) - tick_do_update_jiffies64(now); + tick_sched_do_timer(now); /* * When we are idle and the tick is stopped, we have to touch @@ -802,23 +811,8 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) container_of(timer, struct tick_sched, sched_timer); struct pt_regs *regs = get_irq_regs(); ktime_t now = ktime_get(); - int cpu = smp_processor_id(); -#ifdef CONFIG_NO_HZ - /* - * Check if the do_timer duty was dropped. We don't care about - * concurrency: This happens only when the cpu in charge went - * into a long sleep. If two cpus happen to assign themself to - * this duty, then the jiffies update is still serialized by - * xtime_lock. - */ - if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) - tick_do_timer_cpu = cpu; -#endif - - /* Check, if the jiffies need an update */ - if (tick_do_timer_cpu == cpu) - tick_do_update_jiffies64(now); + tick_sched_do_timer(now); /* * Do not call, when we are not in irq context and have From 9e8f559b08cbc1cfcbf093840a2a760a946cb90f Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Mon, 15 Oct 2012 02:43:03 +0200 Subject: [PATCH 2/3] tick: Consolidate tick handling for high and low res handlers Besides unifying code, this also adds the idle check before processing idle accounting specifics on the low res handler. This way we also generalize this part of the nohz code for !CONFIG_HIGH_RES_TIMERS to prepare for the adaptive tickless features. Signed-off-by: Frederic Weisbecker Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Peter Zijlstra --- kernel/time/tick-sched.c | 55 ++++++++++++++++------------------------ 1 file changed, 22 insertions(+), 33 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 360674c485f5d..68a873af09a85 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -120,6 +120,25 @@ static void tick_sched_do_timer(ktime_t now) tick_do_update_jiffies64(now); } +static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) +{ + /* + * When we are idle and the tick is stopped, we have to touch + * the watchdog as we might not schedule for a really long + * time. This happens on complete idle SMP systems while + * waiting on the login prompt. We also increment the "start of + * idle" jiffy stamp so the idle accounting adjustment we do + * when we go busy again does not account too much ticks. + */ + if (ts->tick_stopped) { + touch_softlockup_watchdog(); + if (is_idle_task(current)) + ts->idle_jiffies++; + } + update_process_times(user_mode(regs)); + profile_tick(CPU_PROFILING); +} + /* * NOHZ - aka dynamic tick functionality */ @@ -675,22 +694,7 @@ static void tick_nohz_handler(struct clock_event_device *dev) dev->next_event.tv64 = KTIME_MAX; tick_sched_do_timer(now); - - /* - * When we are idle and the tick is stopped, we have to touch - * the watchdog as we might not schedule for a really long - * time. This happens on complete idle SMP systems while - * waiting on the login prompt. We also increment the "start - * of idle" jiffy stamp so the idle accounting adjustment we - * do when we go busy again does not account too much ticks. - */ - if (ts->tick_stopped) { - touch_softlockup_watchdog(); - ts->idle_jiffies++; - } - - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING); + tick_sched_handle(ts, regs); while (tick_nohz_reprogram(ts, now)) { now = ktime_get(); @@ -818,23 +822,8 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) * Do not call, when we are not in irq context and have * no valid regs pointer */ - if (regs) { - /* - * When we are idle and the tick is stopped, we have to touch - * the watchdog as we might not schedule for a really long - * time. This happens on complete idle SMP systems while - * waiting on the login prompt. We also increment the "start of - * idle" jiffy stamp so the idle accounting adjustment we do - * when we go busy again does not account too much ticks. - */ - if (ts->tick_stopped) { - touch_softlockup_watchdog(); - if (is_idle_task(current)) - ts->idle_jiffies++; - } - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING); - } + if (regs) + tick_sched_handle(ts, regs); hrtimer_forward(timer, now, tick_period); From 94a571402012e0dfaa23bbbdd64d033f48477d86 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Mon, 15 Oct 2012 16:17:16 +0200 Subject: [PATCH 3/3] tick: Conditionally build nohz specific code in tick handler This optimize a bit the high res tick sched handler. Signed-off-by: Frederic Weisbecker Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Peter Zijlstra --- kernel/time/tick-sched.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 68a873af09a85..766d4c47a4a49 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -122,6 +122,7 @@ static void tick_sched_do_timer(ktime_t now) static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) { +#ifdef CONFIG_NO_HZ /* * When we are idle and the tick is stopped, we have to touch * the watchdog as we might not schedule for a really long @@ -135,6 +136,7 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) if (is_idle_task(current)) ts->idle_jiffies++; } +#endif update_process_times(user_mode(regs)); profile_tick(CPU_PROFILING); }