[PATCH v2 10/11] sched: move cfs task on a CPU with higher capacity
From: peterz@infradead.org (Peter Zijlstra)
Date: 2014-05-29 14:04:34
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On Fri, May 23, 2014 at 05:53:04PM +0200, Vincent Guittot wrote:
quoted hunk ↗ jump to hunk
@@ -7282,6 +7289,12 @@ static inline int nohz_kick_needed(struct rq *rq) if (nr_busy > 1) goto need_kick_unlock; + + if ((rq->cfs.h_nr_running >= 1) + && ((rq->cpu_power * sd->imbalance_pct) < + (rq->cpu_power_orig * 100))) + goto need_kick_unlock; + } sd = rcu_dereference(per_cpu(sd_asym, cpu));
So what happens when a cpu is consistently low on power (say due to a pinned RT task) the balancer would quickly adjust the load level, but this would endlessly kick things into action, even though we're balanced just fine.