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Subject: Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to
 3.6-rc5 on AMD chipsets - bisected
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>, Borislav Petkov <bp@alien8.de>,
        Nikolay Ulyanitsky <lystor@gmail.com>, Mike Galbraith <efault@gmx.de>,
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        Andreas Herrmann <andreas.herrmann3@amd.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>
Date: Mon, 24 Sep 2012 18:07:43 +0200
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On Mon, 2012-09-24 at 08:52 -0700, Linus Torvalds wrote:
> Your patch looks odd, though. Why do you use some complex initial
> value for 'candidate' (nr_cpu_ids) instead of a simple and readable
> one (-1)? 

nr_cpu_ids is the typical no-value value for cpumask operations -- yes
this is annoying and I keep doing it wrong far too often.