Commit 0b013c85 authored Oct 01, 2014 by Syed Rameez Mustafa

sched: Stop task migration to busy CPUs due to power active balance

Power active balance should only be invoked when the destination CPU
is calling load balance with either a CPU_IDLE or a CPU_NEWLY_IDLE
environment. We do not want to push tasks towards busy CPUs even they
are a more power efficient place to run that task. This can cause
higher scheduling latencies due to the resulting load imbalance.

Change-Id: I8e0f242338887d189e2fc17acfb63586e7c40839
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>

parent c5564588

kernel/sched/fair.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -5833,7 +5833,7 @@ static bool update_sd_pick_busiest(struct lb_env *env,
		* seen a busy group yet. We want to prioritize spreading
		* work over power optimization. */
		if (!sds->busiest && sg->group_weight == 1 &&
		sgs->sum_nr_running &&
		sgs->sum_nr_running && (env->idle != CPU_NOT_IDLE) &&
		power_cost_at_freq(env->dst_cpu, 0) <
		power_cost_at_freq(cpumask_first(sched_group_cpus(sg)), 0)) {
		env->flags \|= LBF_PWR_ACTIVE_BALANCE;