Each time a cpu goes to sleep on a NOHZ=y system the timer
wheel is searched for the next timer interrupt. It can take
quite a few cycles to find the next pending timer.
This patch adds a field to tvec_base that caches the result of
__next_timer_interrupt.
The hit ratio is around 80% on my thinkpad under normal use, on
a server I've seen hit ratios from 5% to 95% dependent on the
workload.
-v2: jiffies wrap fixes
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com>
LKML-Reference: <
20090721202505.
7d56a079@skybase>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
spinlock_t lock;
struct timer_list *running_timer;
unsigned long timer_jiffies;
spinlock_t lock;
struct timer_list *running_timer;
unsigned long timer_jiffies;
+ unsigned long next_timer;
struct tvec_root tv1;
struct tvec tv2;
struct tvec tv3;
struct tvec_root tv1;
struct tvec tv2;
struct tvec tv3;
if (timer_pending(timer)) {
detach_timer(timer, 0);
if (timer_pending(timer)) {
detach_timer(timer, 0);
+ if (timer->expires == base->next_timer &&
+ !tbase_get_deferrable(timer->base))
+ base->next_timer = base->timer_jiffies;
ret = 1;
} else {
if (pending_only)
ret = 1;
} else {
if (pending_only)
}
timer->expires = expires;
}
timer->expires = expires;
+ if (time_before(timer->expires, base->next_timer) &&
+ !tbase_get_deferrable(timer->base))
+ base->next_timer = timer->expires;
internal_add_timer(base, timer);
out_unlock:
internal_add_timer(base, timer);
out_unlock:
spin_lock_irqsave(&base->lock, flags);
timer_set_base(timer, base);
debug_timer_activate(timer);
spin_lock_irqsave(&base->lock, flags);
timer_set_base(timer, base);
debug_timer_activate(timer);
+ if (time_before(timer->expires, base->next_timer) &&
+ !tbase_get_deferrable(timer->base))
+ base->next_timer = timer->expires;
internal_add_timer(base, timer);
/*
* Check whether the other CPU is idle and needs to be
internal_add_timer(base, timer);
/*
* Check whether the other CPU is idle and needs to be
base = lock_timer_base(timer, &flags);
if (timer_pending(timer)) {
detach_timer(timer, 1);
base = lock_timer_base(timer, &flags);
if (timer_pending(timer)) {
detach_timer(timer, 1);
+ if (timer->expires == base->next_timer &&
+ !tbase_get_deferrable(timer->base))
+ base->next_timer = base->timer_jiffies;
ret = 1;
}
spin_unlock_irqrestore(&base->lock, flags);
ret = 1;
}
spin_unlock_irqrestore(&base->lock, flags);
ret = 0;
if (timer_pending(timer)) {
detach_timer(timer, 1);
ret = 0;
if (timer_pending(timer)) {
detach_timer(timer, 1);
+ if (timer->expires == base->next_timer &&
+ !tbase_get_deferrable(timer->base))
+ base->next_timer = base->timer_jiffies;
unsigned long expires;
spin_lock(&base->lock);
unsigned long expires;
spin_lock(&base->lock);
- expires = __next_timer_interrupt(base);
+ if (time_before_eq(base->next_timer, base->timer_jiffies))
+ base->next_timer = __next_timer_interrupt(base);
+ expires = base->next_timer;
spin_unlock(&base->lock);
if (time_before_eq(expires, now))
spin_unlock(&base->lock);
if (time_before_eq(expires, now))
INIT_LIST_HEAD(base->tv1.vec + j);
base->timer_jiffies = jiffies;
INIT_LIST_HEAD(base->tv1.vec + j);
base->timer_jiffies = jiffies;
+ base->next_timer = base->timer_jiffies;
timer = list_first_entry(head, struct timer_list, entry);
detach_timer(timer, 0);
timer_set_base(timer, new_base);
timer = list_first_entry(head, struct timer_list, entry);
detach_timer(timer, 0);
timer_set_base(timer, new_base);
+ if (time_before(timer->expires, new_base->next_timer) &&
+ !tbase_get_deferrable(timer->base))
+ new_base->next_timer = timer->expires;
internal_add_timer(new_base, timer);
}
}
internal_add_timer(new_base, timer);
}
}