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From: Ray Lee <ray-lk@madrabbit.org>
Date: Fri, 17 Jun 2011 12:05:29 -0700
Message-ID: <BANLkTimNQm+Cq3nrHpWpBXTvDyDcreLPeg@mail.gmail.com>
Subject: Re: REGRESSION: Performance regressions from switching anon_vma->lock
 to mutex
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Andi Kleen <ak@linux.intel.com>, Shaohua Li <shaohua.li@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        David Miller <davem@davemloft.net>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Russell King <rmk@arm.linux.org.uk>, Paul Mundt <lethal@linux-sh.org>,
        Jeff Dike <jdike@addtoit.com>, Richard Weinberger <richard@nod.at>,
        "Luck, Tony" <tony.luck@intel.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>,
        Namhyung Kim <namhyung@gmail.com>, "Shi, Alex" <alex.shi@intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "Rafael J. Wysocki" <rjw@sisk.pl>
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On Fri, Jun 17, 2011 at 11:22 AM, Tim Chen <tim.c.chen@linux.intel.com> wrote:
> For this patch, I've run it 10 times and got an average throughput of
> 104.9% compared with 2.6.39 vanilla baseline.  Wide variations are seen
> run to run and the difference between max and min throughput is 52% of
> average value.

If the variations are that drastic, it's useful to include the
standard deviation of the mean for each kernel as well. I know it's
only 10 runs, but it's often useful to know if a slow but reliable
process is being replaced by a sometimes faster but more erratic one,
for example.

Just a thought.

~r.
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