From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751302AbdKURH3 (ORCPT ); Tue, 21 Nov 2017 12:07:29 -0500 Received: from mga14.intel.com ([192.55.52.115]:52244 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750794AbdKURH1 (ORCPT ); Tue, 21 Nov 2017 12:07:27 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,432,1505804400"; d="scan'208";a="151846432" Date: Tue, 21 Nov 2017 09:07:14 -0800 From: Andi Kleen To: Jiri Olsa Cc: Andi Kleen , acme@kernel.org, jolsa@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 3/3] perf, tools, script: Allow computing metrics in perf script Message-ID: <20171121170714.GI28112@tassilo.jf.intel.com> References: <20171117214300.32746-1-andi@firstfloor.org> <20171117214300.32746-4-andi@firstfloor.org> <20171120090419.GB5684@krava> <20171120153505.GJ2482@two.firstfloor.org> <20171120155345.GB13495@krava> <20171120160306.GG28112@tassilo.jf.intel.com> <20171121092806.GA25279@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171121092806.GA25279@krava> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 21, 2017 at 10:28:06AM +0100, Jiri Olsa wrote: > On Mon, Nov 20, 2017 at 08:03:06AM -0800, Andi Kleen wrote: > > > > Yes it is. > > > > > > > > It's for the complete sampling period because it is computed > > > > over the delta from the last sample to the previous sample. > > > > > > > > There isn't really a metric at a point, it is always over a interval. > > > > > > agreed, it's the count we meassured from the last sample.. but the > > > 'averaged' word above implies to me we compute some average over the > > > 'sampling' period, which we dont do > > > > Do you have a better word in mind? > > > > AFAIK average is the right word for this because it's the summary > > for that time period. > > the way I understand it is that we take the values from the current > sample and count the metric value.. so the phrase: > > .. the metric computed is averaged over the whole sampling period, > not just for the sample point ... > > does not make sense to me.. because we take the value of that > single 'sample point'.. I dont see any average sum in there The current samples contains the sum of event counts for a sampling period. EventA-1 EventA-2 EventA-3 EventA-4 EventB-1 EventB-2 EventC-3 gap with no events overflow |-----------------------------------------------------------------| period-start period-end ^ ^ | | previous sample current sample So EventA = 4 and EventB = 3 at the sample point I generate a metric, let's say EventA / EventB. It applies to the whole period. But the metric is over a longer time which does not have the same behavior. For example the gap above doesn't have any events, while they are clustered at the beginning and end of the sample period. But we're summing everything together. The metric doesn't know that the gap is different than the busy period. That's what I'm trying to express with averaging. If you still don't like the word I will remove the sentence. I don't have a better term to describe the above. -Andi