Commit bbc8cb5b authored Jul 09, 2010 by Peter Zijlstra Committed by Ingo Molnar Jul 17, 2010

sched: Reduce update_group_power() calls



Currently we update cpu_power() too often, update_group_power() only
updates the local group's cpu_power but it gets called for all groups.

Furthermore, CPU_NEWLY_IDLE invocations will result in all cpus
calling it, even though a slow update of cpu_power is sufficient.

Therefore move the update under 'idle != CPU_NEWLY_IDLE &&
local_group' to reduce superfluous invocations.

Reported-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1278612989.1900.176.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 5343bdb8

kernel/sched_fair.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -2425,13 +2425,13 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
		* domains. In the newly idle case, we will allow all the cpu's
		* to do the newly idle load balance.
		*/
		if (idle != CPU_NEWLY_IDLE && local_group &&
		balance_cpu != this_cpu) {
		if (idle != CPU_NEWLY_IDLE && local_group) {
		if (balance_cpu != this_cpu) {
		*balance = 0;
		return;
		}

		update_group_power(sd, this_cpu);
		}

		/* Adjust by relative CPU power of the group */
		sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) / group->cpu_power;

Admin message