linux-kernel - Re: [PATCH 3/4] sched/fair: Add REBALANCE

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Message-ID: <20160701082442.GO30921@twins.programming.kicks-ass.net>
Date:	Fri, 1 Jul 2016 10:24:42 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	James Hartsock <hartsjc@...hat.com>,
	Rik van Riel <riel@...hat.com>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Kirill Tkhai <ktkhai@...allels.com>
Subject: Re: [PATCH 3/4] sched/fair: Add REBALANCE_AFFINITY rebalancing code

On Fri, Jul 01, 2016 at 09:35:46AM +0200, Jiri Olsa wrote:
> well this is issue our partner met in the setup,
> and I'm not sure what was their motivation for that,
> perhaps James could clarify in here..
> 
> I tried to make the 'scratch that itch' solution as
> mentioned in earlier discussion.
> 
> So IIUIC what you say is that it needs to be more generic
> solution..?  I'll continue staring at it then ;-)

I just want to know what problem we're trying to solve..

Because it appears this is running 1 task each on a 'weird' subset of
cpus and things going badly. If this really is the case, then teaching
active balance to only move tasks to idle cpus or something should also
cure things.

Also, I'm curious why people set such weird masks.