linux-kernel - Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for BALANCE

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Date:	Thu, 28 May 2015 10:27:22 -0400
From:	Josef Bacik <jbacik@...com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	<riel@...hat.com>, <mingo@...hat.com>,
	<linux-kernel@...r.kernel.org>, <umgwanakikbuti@...il.com>,
	<morten.rasmussen@....com>
Subject: Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for
 BALANCE_WAKE

On 05/28/2015 07:05 AM, Peter Zijlstra wrote:
>
> So maybe you want something like the below; that cures the thing Morten
> raised, and we continue looking for sd, even after we found affine_sd.
>
> It also avoids the pointless idle_cpu() check Mike raised by making
> select_idle_sibling() return -1 if it doesn't find anything.
>
> Then it continues doing the full balance IFF sd was set, which is keyed
> off of sd->flags.
>
> And note (as Mike already said), BALANCE_WAKE does _NOT_ look for idle
> CPUs, it looks for the least loaded CPU. And its damn expensive.
>

Sorry I was just assuming based on the commit message when WAKE_IDLE was 
removed, this isn't my area.

>
> Rewriting this entire thing is somewhere on the todo list :/

Thanks I'm building and deploying this so I can run our perf test, I'll 
have results in ~3 hours.

Josef
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