From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753783AbaHAIAe (ORCPT ); Fri, 1 Aug 2014 04:00:34 -0400 Received: from mga14.intel.com ([192.55.52.115]:16190 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753459AbaHAIAd (ORCPT ); Fri, 1 Aug 2014 04:00:33 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,778,1400050800"; d="scan'208";a="570360617" Date: Fri, 1 Aug 2014 07:58:25 +0800 From: Yuyang Du To: Peter Zijlstra Cc: Aaron Lu , Rik van Riel , LKML , lkp@01.org, jhladky@redhat.com, Fengguang Wu Subject: Re: [LKP] [sched/numa] a43455a1d57: +94.1% proc-vmstat.numa_hint_faults_local Message-ID: <20140731235825.GH28673@intel.com> References: <53d70ee6.JsUEmW5dWsv8dev+%fengguang.wu@intel.com> <53D72FF5.90908@intel.com> <20140729023940.37b6aebc@annuminas.surriel.com> <20140731104241.GA9918@twins.programming.kicks-ass.net> <20140801020330.GA30211@aaronlu.sh.intel.com> <20140801072911.GE19379@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20140801072911.GE19379@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 01, 2014 at 09:29:11AM +0200, Peter Zijlstra wrote: > On Fri, Aug 01, 2014 at 10:03:30AM +0800, Aaron Lu wrote: > > > > > ebe06187bf2aec1 a43455a1d572daf7b730fe12e > > > > > --------------- ------------------------- > > > > > 94500 ~ 3% +115.6% 203711 ~ 6% ivb42/hackbench/50%-threads-pipe > > > > > 67745 ~ 4% +64.1% 111174 ~ 5% lkp-snb01/hackbench/50%-threads-socket > > > > > 162245 ~ 3% +94.1% 314885 ~ 6% TOTAL proc-vmstat.numa_hint_faults_local > > > It means, for commit ebe06187bf2aec1, the number for > > num_hint_local_faults is 94500 for ivb42 machine and 67745 for lkp-snb01 > > machine. The 3%, 4% following that number means the deviation of the > > different runs to their average(we usually run it multiple times to > > phase out possible sharp values). We should probably remove that > > percentage, as they cause confusion if no detailed explanation and may > > not mean much to the commit author and others(if the deviation is big > > enough, we should simply drop that result). > > Nah, variance is good, but the typical symbol would be +- or the fancy > ±. > > ~ when used as a unary op means 'approx' or 'about' or 'same order' > ~ when used as a binary op means equivalence, a weaker equal, often in > the vein of the unary op meaning. > > Also see: http://en.wikipedia.org/wiki/Tilde#Mathematics > > So while I think having a measure of variance is good, I think you > picked entirely the wrong symbol. Or, maybe you can use σ (lower case sigma) to indicate stddev, :)