linux-kernel - Re: [PATCH v2 04/13] sched: Introduce SD_ASYM_CPUCAPACITY sched

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Message-ID: <20160711104218.GG12540@e105550-lin.cambridge.arm.com>
Date:	Mon, 11 Jul 2016 11:42:18 +0100
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	mingo@...hat.com, dietmar.eggemann@....com, yuyang.du@...el.com,
	vincent.guittot@...aro.org, mgalbraith@...e.de,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 04/13] sched: Introduce SD_ASYM_CPUCAPACITY
 sched_domain topology flag

On Mon, Jul 11, 2016 at 11:55:23AM +0200, Peter Zijlstra wrote:
> On Wed, Jun 22, 2016 at 06:03:15PM +0100, Morten Rasmussen wrote:
> > Add a topology flag to the sched_domain hierarchy indicating
> > sched_groups at this sched_domain level having different per cpu
> > capacity (e.g. big.LITTLE big-only and little-only groups) or groups in
> > sibling domains with different capacity.
> 
> >                                          IOW, domains not spanning cpus
> > of all available capacities up until and including the first level
> > spanning cpus of all capacities available system wide.
> 
> This ^, which would be SD1 below, why? I would expect only SD2 to be
> tagged, since that does indeed have asymmetric capacities.

That would make most sense, but it complicates how we can use the flag.
See reply to your related question for patch #5.