linux-kernel - Re: [PATCH 3/3] sched: limit cpu search and rotate search window for scalability

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Message-ID: <20180424124855.GT4082@hirez.programming.kicks-ass.net>
Date:   Tue, 24 Apr 2018 14:48:55 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     subhra mazumdar <subhra.mazumdar@...cle.com>
Cc:     linux-kernel@...r.kernel.org, mingo@...hat.com,
        daniel.lezcano@...aro.org, steven.sistare@...cle.com,
        dhaval.giani@...cle.com, rohit.k.jain@...cle.com
Subject: Re: [PATCH 3/3] sched: limit cpu search and rotate search window for
 scalability

On Mon, Apr 23, 2018 at 05:41:16PM -0700, subhra mazumdar wrote:
> Lower the lower limit of idle cpu search in select_idle_cpu() and also put
> an upper limit. This helps in scalability of the search by restricting the
> search window. Also rotating the search window with help of next_cpu
> ensures any idle cpu is eventually found in case of high load.

So this patch does 2 (possibly 3) things, that's not good.