From 52b7b8a37c3da55885a9b7e60b2c4db6cf2dbeff Mon Sep 17 00:00:00 2001 From: Dietmar Eggemann Date: Sun, 10 May 2015 15:17:32 +0100 Subject: [PATCH] sched: Consider a not over-utilized energy-aware system as balanced In case the system operates below the tipping point indicator, introduced in ("sched: Add over-utilization/tipping point indicator"), bail out in find_busiest_group after the dst and src group statistics have been checked. There is simply no need to move usage around because all involved cpus still have spare cycles available. For an energy-aware system below its tipping point, we rely on the task placement of the wakeup path. This works well for short running tasks. The existence of long running tasks on one of the involved cpus lets the system operate over its tipping point. To be able to move such a task (whose load can't be used to average the load among the cpus) from a src cpu with lower capacity than the dst_cpu, an additional rule has to be implemented in need_active_balance. Signed-off-by: Dietmar Eggemann --- kernel/sched/fair.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 682b4ae9ebd7..ae4f1ee9cf0c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7194,6 +7194,10 @@ static struct sched_group *find_busiest_group(struct lb_env *env) * this level. */ update_sd_lb_stats(env, &sds); + + if (energy_aware() && !env->dst_rq->rd->overutilized) + goto out_balanced; + local = &sds.local_stat; busiest = &sds.busiest_stat; -- 2.20.1