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Subject: Re: [PATCH] sched: fix updating sd->balance_interval in
 idle_balance()
From: Peter Zijlstra <peterz@infradead.org>
To: Nikhil Rao <ncrao@google.com>
Cc: Ingo Molnar <mingo@elte.hu>, Mike Galbraith <efault@gmx.de>,
       Venkatesh Pallipadi <venki@google.com>, linux-kernel@vger.kernel.org
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Date: Thu, 20 May 2010 09:16:49 +0200
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On Wed, 2010-05-19 at 16:45 -0700, Nikhil Rao wrote:
> sd->balance_interval is updated incorrectly when SD_BALANCE_NEWIDLE is not set
> in sd->flags. This patch updates sd->balance_interval only when we balance the
> domain. 

I really need more than that.

Why is it wrong, what are the (measurable) effects of changing it and
how did it come to be this way.

I could of course go and try to reverse engineer your patch, but it
would be awesome if I didn't have to.