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Date: Fri, 1 Jul 2016 20:52:29 -0400
From: "Emilio G. Cota" <cota@braap.org>
Message-ID: <20160702005229.GC2295@flamenco>
References: <1467389770-9738-1-git-send-email-alex.bennee@linaro.org>
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Subject: Re: [Qemu-devel] [PATCH 0/2] Reduce lock contention on TCG hot-path
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To: Alex =?iso-8859-1?Q?Benn=E9e?= <alex.bennee@linaro.org>
Cc: mttcg@listserver.greensocs.com, qemu-devel@nongnu.org, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, serge.fdrv@gmail.com, bobby.prani@gmail.com, rth@twiddle.net, mark.burton@greensocs.com, pbonzini@redhat.com, jan.kiszka@siemens.com, peter.maydell@linaro.org, claudio.fontana@huawei.com

On Fri, Jul 01, 2016 at 17:16:08 +0100, Alex Bennée wrote:
(snip)
> run 1: ret=0 (PASS), time=4.755824 (1/1)
> run 2: ret=0 (PASS), time=4.756076 (2/2)
> run 3: ret=0 (PASS), time=4.755916 (3/3)
> run 4: ret=0 (PASS), time=4.755853 (4/4)
> run 5: ret=0 (PASS), time=4.755929 (5/5)
> Results summary:
> 0: 5 times (100.00%), avg time 4.755920 (0.000000 deviation)

(snip)
> run 1: ret=0 (PASS), time=9.761559 (1/1)
> run 2: ret=0 (PASS), time=9.511616 (2/2)
> run 3: ret=0 (PASS), time=9.761713 (3/3)
> run 4: ret=0 (PASS), time=10.262504 (4/4)
> run 5: ret=0 (PASS), time=9.762059 (5/5)
> Results summary:
> 0: 5 times (100.00%), avg time 9.811890 (0.060150 deviation)

This is a needless diversion, but I was explaining this stuff today
to a student so couldn't help but notice.

The computed deviations seem overly small. For instance, the corrected sample
standard deviation ( https://en.wikipedia.org/wiki/Standard_deviation )
(which is usually referred to as "standard deviation", or "error")
for the last test should be 0.2742 instead of 0.06.

How are they being computed? I tried to find the source of your script
(in the kvm-unit-tests repo) but couldn't find it.

Thanks,

		Emilio