hrtimer: reduce calls to hrtimer_get_softirq_time()
It seems that hrtimer_run_queues() is calling hrtimer_get_softirq_time() more
often than it needs to. This can cause frequent contention on systems with
large numbers of processors/cores.
With this patch, hrtimer_run_queues only calls hrtimer_get_softirq_time() if
there is a pending timer in one of the hrtimer bases, and only once.
This also combines hrtimer_run_queues() and the inline run_hrtimer_queue()
into one function.
[ tglx@linutronix.de: coding style ]
Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index c642ef7..70d4adc 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1238,51 +1238,51 @@
/*
* Called from hardirq context every jiffy
*/
-static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base,
- int index)
-{
- struct rb_node *node;
- struct hrtimer_clock_base *base = &cpu_base->clock_base[index];
-
- if (!base->first)
- return;
-
- if (base->get_softirq_time)
- base->softirq_time = base->get_softirq_time();
-
- spin_lock(&cpu_base->lock);
-
- while ((node = base->first)) {
- struct hrtimer *timer;
-
- timer = rb_entry(node, struct hrtimer, node);
- if (base->softirq_time.tv64 <= timer->expires.tv64)
- break;
-
- if (timer->cb_mode == HRTIMER_CB_SOFTIRQ) {
- __remove_hrtimer(timer, base, HRTIMER_STATE_PENDING, 0);
- list_add_tail(&timer->cb_entry,
- &base->cpu_base->cb_pending);
- continue;
- }
-
- __run_hrtimer(timer);
- }
- spin_unlock(&cpu_base->lock);
-}
-
void hrtimer_run_queues(void)
{
+ struct rb_node *node;
struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
- int i;
+ struct hrtimer_clock_base *base;
+ int index, gettime = 1;
if (hrtimer_hres_active())
return;
- hrtimer_get_softirq_time(cpu_base);
+ for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
+ base = &cpu_base->clock_base[index];
- for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
- run_hrtimer_queue(cpu_base, i);
+ if (!base->first)
+ continue;
+
+ if (gettime) {
+ hrtimer_get_softirq_time(cpu_base);
+ gettime = 0;
+ }
+
+ if (base->get_softirq_time)
+ base->softirq_time = base->get_softirq_time();
+
+ spin_lock(&cpu_base->lock);
+
+ while ((node = base->first)) {
+ struct hrtimer *timer;
+
+ timer = rb_entry(node, struct hrtimer, node);
+ if (base->softirq_time.tv64 <= timer->expires.tv64)
+ break;
+
+ if (timer->cb_mode == HRTIMER_CB_SOFTIRQ) {
+ __remove_hrtimer(timer, base,
+ HRTIMER_STATE_PENDING, 0);
+ list_add_tail(&timer->cb_entry,
+ &base->cpu_base->cb_pending);
+ continue;
+ }
+
+ __run_hrtimer(timer);
+ }
+ spin_unlock(&cpu_base->lock);
+ }
}
/*