Date: Fri, 23 Aug 2013 13:51:54 +0900
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Turner <pjt@google.com>, Ingo Molnar <mingo@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, Mike Galbraith <efault@gmx.de>,
        Alex Shi <alex.shi@intel.com>,
        Preeti U Murthy <preeti@linux.vnet.ibm.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Morten Rasmussen <morten.rasmussen@arm.com>,
        Namhyung Kim <namhyung@kernel.org>, Lei Wen <leiwen@marvell.com>,
        Rik van Riel <riel@surriel.com>
Subject: Re: [PATCH 02/10] sched: Factor out code to should_we_balance()
Message-ID: <20130823045154.GB22605@lge.com>
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On Thu, Aug 22, 2013 at 12:42:57PM +0200, Peter Zijlstra wrote:
> > >
> > > +redo:
> > 
> > One behavioral change worth noting here is that in the redo case if a
> > CPU has become idle we'll continue trying to load-balance in the
> > !new-idle case.
> > 
> > This could be unpleasant in the case where a package has a pinned busy
> > core allowing this and a newly idle cpu to start dueling for load.
> > 
> > While more deterministically bad in this case now, it could racily do
> > this before anyway so perhaps not worth worrying about immediately.
> 
> Ah, because the old code would effectively redo the check and find the
> idle cpu and thereby our cpu would no longer be the balance_cpu.
> 
> Indeed. And I don't think this was an intentional change. I'll go put
> the redo back before should_we_balance().

Ah, yes.
It isn't my intention. Please fix it.

Thanks.
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