linux-kernel - Re: [PATCH 4/4] sched,fair: remove effective

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Message-ID: <20170626150401.GC4941@worktop>
Date:   Mon, 26 Jun 2017 17:04:01 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Rik van Riel <riel@...hat.com>
Cc:     linux-kernel@...r.kernel.org, jhladky@...hat.com, mingo@...nel.org,
        mgorman@...e.de
Subject: Re: [PATCH 4/4] sched,fair: remove effective_load

On Mon, Jun 26, 2017 at 10:55:41AM -0400, Rik van Riel wrote:
> On Mon, 2017-06-26 at 16:46 +0200, Peter Zijlstra wrote:
> > On Mon, Jun 26, 2017 at 04:44:37PM +0200, Peter Zijlstra wrote:
> > > On Fri, Jun 23, 2017 at 12:55:30PM -0400, riel@...hat.com wrote:
> > > > From: Rik van Riel <riel@...hat.com>
> > > > 
> > > > The function effective_load was only used by the NUMA balancing
> > > > code, and not by the regular load balancing code. Now that the
> > > > NUMA balancing code no longer uses it either, get rid of it.
> > > 
> > > Hmm,... funny. It used to be used by wake-affine. I'll have to go
> > > check
> > > what happened.
> > 
> > Ah, it fell pray to that LLC == NUMA confusion from the previous
> > patch.
> > 
> > That really looks buggered.
> 
> Do the changelog or comments of that patch need fixing,
> to avoid LLC / NUMA confusion?

Neither, I think the code is actually wrong for the case where LLC <
NUMA (a somewhat rare case these days, granted, but something that might
still happen on !x86 perhaps).