linux-kernel - Re: [PATCH v8 1/2] sched/deadline: Add support for SD_PREFER_SIBLING on find_later

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Message-ID: <20170822055530.GF20323@X58A-UD3R>
Date:   Tue, 22 Aug 2017 14:55:30 +0900
From:   Byungchul Park <byungchul.park@....com>
To:     Juri Lelli <juri.lelli@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>, mingo@...nel.org,
        joel.opensrc@...il.com, linux-kernel@...r.kernel.org,
        juri.lelli@...il.com, rostedt@...dmis.org, kernel-team@....com
Subject: Re: [PATCH v8 1/2] sched/deadline: Add support for SD_PREFER_SIBLING
 on find_later_rq()

On Mon, Aug 21, 2017 at 03:07:57PM +0100, Juri Lelli wrote:
> > Consider a 4 core, SMT2 system:
> > 
> > LLC	[0         -         7]
> > 
> > SMT	[0,1] [2,3] [4,5] [6,7]
> > 
> > If we do a wake-up on CPU0, we'll find CPU1, mark that as fallback,
> > continue up the domain tree, exclude 0,1 from 0-7 and find CPU2.
> > 
> > A next wakeup on CPU0 does the same and will find CPU3, fully loading
> > that core, instead of considering CPU4 first.
> > 
> 
> Ah, right, I see. Thanks for explaining.
> 
> Byungchul, maybe you could add this explanation as a comment?

Yes. Good idea. I will add it.

Thank you,
Byungchul