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author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-12 03:22:46 +0100 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-12 03:22:46 +0100 |
commit | b64c5fda3868cb29d5dae0909561aa7d93fb7330 (patch) | |
tree | 2ac4be822f32fe5a8e8f33138be81b221ff52384 /kernel/time/tick-sched.c | |
parent | Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/ker... (diff) | |
parent | Merge branch 'fortglx/3.8/time' of git://git.linaro.org/people/jstultz/linux ... (diff) | |
download | linux-b64c5fda3868cb29d5dae0909561aa7d93fb7330.tar.xz linux-b64c5fda3868cb29d5dae0909561aa7d93fb7330.zip |
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core timer changes from Ingo Molnar:
"It contains continued generic-NOHZ work by Frederic and smaller
cleanups."
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: Kill xtime_lock, replacing it with jiffies_lock
clocksource: arm_generic: use this_cpu_ptr per-cpu helper
clocksource: arm_generic: use integer math helpers
time/jiffies: Make clocksource_jiffies static
clocksource: clean up parse_pmtmr()
tick: Correct the comments for tick_sched_timer()
tick: Conditionally build nohz specific code in tick handler
tick: Consolidate tick handling for high and low res handlers
tick: Consolidate timekeeping handling code
Diffstat (limited to 'kernel/time/tick-sched.c')
-rw-r--r-- | kernel/time/tick-sched.c | 131 |
1 files changed, 58 insertions, 73 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 80e061a9ed09..d58e552d9fd1 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -31,7 +31,7 @@ static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched); /* - * The time, when the last jiffy update happened. Protected by xtime_lock. + * The time, when the last jiffy update happened. Protected by jiffies_lock. */ static ktime_t last_jiffies_update; @@ -49,14 +49,14 @@ static void tick_do_update_jiffies64(ktime_t now) ktime_t delta; /* - * Do a quick check without holding xtime_lock: + * Do a quick check without holding jiffies_lock: */ delta = ktime_sub(now, last_jiffies_update); if (delta.tv64 < tick_period.tv64) return; - /* Reevalute with xtime_lock held */ - write_seqlock(&xtime_lock); + /* Reevalute with jiffies_lock held */ + write_seqlock(&jiffies_lock); delta = ktime_sub(now, last_jiffies_update); if (delta.tv64 >= tick_period.tv64) { @@ -79,7 +79,7 @@ static void tick_do_update_jiffies64(ktime_t now) /* Keep the tick_next_period variable up to date */ tick_next_period = ktime_add(last_jiffies_update, tick_period); } - write_sequnlock(&xtime_lock); + write_sequnlock(&jiffies_lock); } /* @@ -89,15 +89,58 @@ static ktime_t tick_init_jiffy_update(void) { ktime_t period; - write_seqlock(&xtime_lock); + write_seqlock(&jiffies_lock); /* Did we start the jiffies update yet ? */ if (last_jiffies_update.tv64 == 0) last_jiffies_update = tick_next_period; period = last_jiffies_update; - write_sequnlock(&xtime_lock); + write_sequnlock(&jiffies_lock); 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 + * jiffies_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); +} + +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 + * 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++; + } +#endif + update_process_times(user_mode(regs)); + profile_tick(CPU_PROFILING); +} + /* * NOHZ - aka dynamic tick functionality */ @@ -282,11 +325,11 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, /* Read jiffies and the time when jiffies were updated last */ do { - seq = read_seqbegin(&xtime_lock); + seq = read_seqbegin(&jiffies_lock); last_update = last_jiffies_update; last_jiffies = jiffies; time_delta = timekeeping_max_deferment(); - } while (read_seqretry(&xtime_lock, seq)); + } while (read_seqretry(&jiffies_lock, seq)); if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || printk_needs_cpu(cpu) || arch_needs_cpu(cpu)) { @@ -652,40 +695,12 @@ 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); - - /* - * 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_do_timer(now); + tick_sched_handle(ts, regs); while (tick_nohz_reprogram(ts, now)) { now = ktime_get(); @@ -806,45 +821,15 @@ 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 * 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); @@ -878,7 +863,7 @@ void tick_setup_sched_timer(void) /* Get the next period (per cpu) */ hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); - /* Offset the tick to avert xtime_lock contention. */ + /* Offset the tick to avert jiffies_lock contention. */ if (sched_skew_tick) { u64 offset = ktime_to_ns(tick_period) >> 1; do_div(offset, num_possible_cpus()); |