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Date: Thu, 14 Nov 2013 09:30:37 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        Preeti Murthy <preeti.lkml@gmail.com>, mingo@kernel.org, hpa@zytor.com,
        linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        mikey@neuling.org, linux-tip-commits@vger.kernel.org
Subject: Re: [PATCH v2] sched: Check sched_domain before computing group
 power.
Message-ID: <20131114083037.GT21461@twins.programming.kicks-ass.net>
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On Thu, Nov 14, 2013 at 11:36:27AM +0530, Preeti U Murthy wrote:
> However I was thinking that a better fix would be to reorder the way we call
> update_group_power() and cpu_attach_domain(). Why do we need to do
> update_group_power() of the groups of the sched domains that would probably
> degenerate in cpu_attach_domain()? So it seemed best to move update_group_power()
> to after cpu_attach_domain() so that it saves unnecessary iterations over
> sched domains which could degenerate, and it fixes the issue that you have brought out
> as well. See below for the patch:

So how is publishing the domain tree before we've set these values at
all going to help avoid the divide-by-zero problem?

Also its just terribly bad form to publish something before you're done
with initialization.