From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35518) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bJNOY-0004dx-Bf for qemu-devel@nongnu.org; Sat, 02 Jul 2016 12:03:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bJNOT-0007GR-CX for qemu-devel@nongnu.org; Sat, 02 Jul 2016 12:03:49 -0400 Received: from mail-wm0-x241.google.com ([2a00:1450:400c:c09::241]:32888) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bJNOT-0007Fg-4Z for qemu-devel@nongnu.org; Sat, 02 Jul 2016 12:03:45 -0400 Received: by mail-wm0-x241.google.com with SMTP id r201so12001888wme.0 for ; Sat, 02 Jul 2016 09:03:43 -0700 (PDT) Sender: Paolo Bonzini References: <1467389770-9738-1-git-send-email-alex.bennee@linaro.org> <20160702005229.GC2295@flamenco> <87ziq0ikji.fsf@linaro.org> From: Paolo Bonzini Message-ID: <77b9df19-3666-e48e-5040-b370e3e64f62@redhat.com> Date: Sat, 2 Jul 2016 18:03:36 +0200 MIME-Version: 1.0 In-Reply-To: <87ziq0ikji.fsf@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH 0/2] Reduce lock contention on TCG hot-path List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?Q?Alex_Benn=c3=a9e?= , "Emilio G. Cota" Cc: mttcg@listserver.greensocs.com, peter.maydell@linaro.org, claudio.fontana@huawei.com, jan.kiszka@siemens.com, mark.burton@greensocs.com, a.rigo@virtualopensystems.com, qemu-devel@nongnu.org, serge.fdrv@gmail.com, bobby.prani@gmail.com, rth@twiddle.net, fred.konrad@greensocs.com On 02/07/2016 09:08, Alex Bennée wrote: > Hmm I was doing from memory but it should be the mean of the sum of the > squares of the deviation: > > # calculate deviation > deviation = 0 > for r in res: > deviation += (r.time - avg_time)**2 > > deviation = deviation / count This is the population variance. "Standard deviation" and "variance" usually refer to the sample standard deviation and sample variance, where you divide by count-1. For the population stdev and sample stdev you have to take the square root. LibreOffice agrees with Emilio, giving a sample stdev of 0.2742 and a population stdev of 0.2453 Paolo