Date: Sat, 15 Aug 2015 11:33:32 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: mingo@redhat.com, vincent.guittot@linaro.org, daniel.lezcano@linaro.org,
        Dietmar Eggemann <Dietmar.Eggemann@arm.com>, yuyang.du@intel.com,
        mturquette@baylibre.com, rjw@rjwysocki.net,
        Juri Lelli <Juri.Lelli@arm.com>, sgurrappadi@nvidia.com,
        pang.xunlei@zte.com.cn, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org
Subject: Re: [RFCv5 PATCH 35/46] sched: Disable energy-unfriendly nohz kicks
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On Tue, Jul 07, 2015 at 07:24:18PM +0100, Morten Rasmussen wrote:
> With energy-aware scheduling enabled nohz_kick_needed() generates many
> nohz idle-balance kicks which lead to nothing when multiple tasks get
> packed on a single cpu to save energy. This causes unnecessary wake-ups
> and hence wastes energy. Make these conditions depend on !energy_aware()
> for now until the energy-aware nohz story gets sorted out.

The patch does slightly more; it also allows the kick if over utilized.

But disabling this will allow getting 'stuck' in certain over loaded
situations because we're not kicking the balancer.

I think you need more justification for doing this.

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