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Commit 833883d9 authored by Dimitri Sivanich's avatar Dimitri Sivanich Committed by Thomas Gleixner
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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: default avatarDimitri Sivanich <sivanich@sgi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 833df317

kernel/hrtimer.c

+32 −32
Original line number Diff line number Diff line
@@ -1238,15 +1238,27 @@ void hrtimer_run_pending(void) 
/*

 * Called from hardirq context every jiffy

 */

static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base,

				     int index)

void hrtimer_run_queues(void)

{

	struct rb_node *node;

	struct hrtimer_clock_base *base = &cpu_base->clock_base[index];

	struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);

	struct hrtimer_clock_base *base;

	int index, gettime = 1;



	if (!base->first)

	if (hrtimer_hres_active())

		return;



	for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {

		base = &cpu_base->clock_base[index];



		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();
@@ -1260,7 +1272,8 @@ static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base, 
				break;



			if (timer->cb_mode == HRTIMER_CB_SOFTIRQ) {

			__remove_hrtimer(timer, base, HRTIMER_STATE_PENDING, 0);

				__remove_hrtimer(timer, base,

					HRTIMER_STATE_PENDING, 0);

				list_add_tail(&timer->cb_entry,

					&base->cpu_base->cb_pending);

				continue;
@@ -1270,19 +1283,6 @@ static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base, 
		}

		spin_unlock(&cpu_base->lock);

	}



void hrtimer_run_queues(void)

{

	struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);

	int i;



	if (hrtimer_hres_active())

		return;



	hrtimer_get_softirq_time(cpu_base);



	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)

		run_hrtimer_queue(cpu_base, i);

}



/*