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author | Thomas Gleixner <tglx@linutronix.de> | 2012-05-25 22:08:58 +0000 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2012-06-06 13:49:01 +0200 |
commit | 99d5f3aac674fe081ffddd2dbb8946ccbc14c410 (patch) | |
tree | d4a6cb5f0d4906f2ce983d2db8b4046b96706f53 /kernel/timer.c | |
parent | facbb4a7efbd658046bf615f03cd97a1504785d8 (diff) | |
download | linux-stable-99d5f3aac674fe081ffddd2dbb8946ccbc14c410.tar.gz linux-stable-99d5f3aac674fe081ffddd2dbb8946ccbc14c410.tar.bz2 linux-stable-99d5f3aac674fe081ffddd2dbb8946ccbc14c410.zip |
timers: Add accounting of non deferrable timers
The code in get_next_timer_interrupt() is suboptimal as it has to run
through the cascade to find the next expiring timer. On a completely
idle core we should only do that when there is an active timer
enqueued and base->next_timer does not give us a fast answer.
Add accounting of the active timers to the now consolidated
attach/detach code. I deliberately avoided sanity checks because the
code is fully symetric and any fiddling with timers w/o using the API
functions will lead to cute explosions anyway. ulong is big enough
even on 32bit and if we really run into the situation to have more
than 1<<32 timers enqueued there, then we are definitely not in a
state to go idle and run through that code.
This allows us to fix another shortcoming of get_next_timer_interrupt().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Gilad Ben-Yossef <gilad@benyossef.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20120525214819.236377028@linutronix.de
Diffstat (limited to 'kernel/timer.c')
-rw-r--r-- | kernel/timer.c | 31 |
1 files changed, 23 insertions, 8 deletions
diff --git a/kernel/timer.c b/kernel/timer.c index 7207690b5353..7fada698bd1a 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -77,6 +77,7 @@ struct tvec_base { struct timer_list *running_timer; unsigned long timer_jiffies; unsigned long next_timer; + unsigned long active_timers; struct tvec_root tv1; struct tvec tv2; struct tvec tv3; @@ -377,11 +378,13 @@ static void internal_add_timer(struct tvec_base *base, struct timer_list *timer) { __internal_add_timer(base, timer); /* - * Update base->next_timer if this is the earliest one. + * Update base->active_timers and base->next_timer */ - if (time_before(timer->expires, base->next_timer) && - !tbase_get_deferrable(timer->base)) - base->next_timer = timer->expires; + if (!tbase_get_deferrable(timer->base)) { + if (time_before(timer->expires, base->next_timer)) + base->next_timer = timer->expires; + base->active_timers++; + } } #ifdef CONFIG_TIMER_STATS @@ -678,6 +681,14 @@ static inline void detach_timer(struct timer_list *timer, bool clear_pending) entry->prev = LIST_POISON2; } +static inline void +detach_expired_timer(struct timer_list *timer, struct tvec_base *base) +{ + detach_timer(timer, true); + if (!tbase_get_deferrable(timer->base)) + timer->base->active_timers--; +} + static int detach_if_pending(struct timer_list *timer, struct tvec_base *base, bool clear_pending) { @@ -685,9 +696,11 @@ static int detach_if_pending(struct timer_list *timer, struct tvec_base *base, return 0; detach_timer(timer, clear_pending); - if (timer->expires == base->next_timer && - !tbase_get_deferrable(timer->base)) - base->next_timer = base->timer_jiffies; + if (!tbase_get_deferrable(timer->base)) { + timer->base->active_timers--; + if (timer->expires == base->next_timer) + base->next_timer = base->timer_jiffies; + } return 1; } @@ -1175,7 +1188,7 @@ static inline void __run_timers(struct tvec_base *base) timer_stats_account_timer(timer); base->running_timer = timer; - detach_timer(timer, true); + detach_expired_timer(timer, base); spin_unlock_irq(&base->lock); call_timer_fn(timer, fn, data); @@ -1701,6 +1714,7 @@ static int __cpuinit init_timers_cpu(int cpu) base->timer_jiffies = jiffies; base->next_timer = base->timer_jiffies; + base->active_timers = 0; return 0; } @@ -1711,6 +1725,7 @@ static void migrate_timer_list(struct tvec_base *new_base, struct list_head *hea while (!list_empty(head)) { timer = list_first_entry(head, struct timer_list, entry); + /* We ignore the accounting on the dying cpu */ detach_timer(timer, false); timer_set_base(timer, new_base); internal_add_timer(new_base, timer); |