Commit 4e85876a authored Jul 04, 2016 by Thomas Gleixner Committed by Ingo Molnar Jul 07, 2016

timers: Only wake softirq if necessary



With the wheel forwading in place and with the HZ=1000 4ms folding we can
avoid running the softirq at all.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.607650550@linutronix.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent a683f390

kernel/time/timer.c

+11 −0

Original line number	Original line	Diff line number	Diff line
	@@ -1608,7 +1608,18 @@ static void run_timer_softirq(struct softirq_action *h)
	*/		*/
	void run_local_timers(void)		void run_local_timers(void)
	{		{
			struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);

	hrtimer_run_queues();		hrtimer_run_queues();
			/* Raise the softirq only if required. */
			if (time_before(jiffies, base->clk)) {
			if (!IS_ENABLED(CONFIG_NO_HZ_COMMON) \|\| !base->nohz_active)
			return;
			/* CPU is awake, so check the deferrable base. */
			base++;
			if (time_before(jiffies, base->clk))
			return;
			}
	raise_softirq(TIMER_SOFTIRQ);		raise_softirq(TIMER_SOFTIRQ);
	}		}

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