| From | Morten Rasmussen <> | Subject | [RFCv3 PATCH 44/48] sched: Tipping point from energy-aware to conventional load balancing | Date | Wed, 4 Feb 2015 18:31:21 +0000 |
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From: Dietmar Eggemann <dietmar.eggemann@arm.com>
Energy-aware load balancing bases on cpu usage so the upper bound of its operational range is a fully utilized cpu. Above this tipping point it makes more sense to use weighted_cpuload to preserve smp_nice. This patch implements the tipping point detection in update_sg_lb_stats as if one cpu is over-utilized the current energy-aware load balance operation will fall back into the conventional weighted load based one.
cc: Ingo Molnar <mingo@redhat.com> cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> --- kernel/sched/fair.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 6b79603..4849bad 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6723,6 +6723,10 @@ static inline void update_sg_lb_stats(struct lb_env *env, sgs->sum_weighted_load += weighted_cpuload(i); if (idle_cpu(i)) sgs->idle_cpus++; + + /* If cpu is over-utilized, bail out of ea */ + if (env->use_ea && cpu_overutilized(i, env->sd)) + env->use_ea = false; } /* Adjust by relative CPU capacity of the group */ -- 1.9.1
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