From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757504Ab3LWOog (ORCPT ); Mon, 23 Dec 2013 09:44:36 -0500 Received: from mail-pd0-f171.google.com ([209.85.192.171]:45055 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753518Ab3LWOof (ORCPT ); Mon, 23 Dec 2013 09:44:35 -0500 Message-ID: <52B84C49.70001@gmail.com> Date: Mon, 23 Dec 2013 09:44:25 -0500 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Frederic Weisbecker CC: Joseph Schuchart , Ingo Molnar , Peter Zijlstra , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , thomas.ilsche@tu-dresden.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Perf: Correct Assumptions about Sample Timestamps in Passes References: <528484CB.7@tu-dresden.de> <20131114083930.GC16543@gmail.com> <528490DE.4080204@tu-dresden.de> <20131114100552.GA5064@gmail.com> <528E1EE6.9040407@tu-dresden.de> <20131127135137.GA24403@gmail.com> <52B437AA.4090102@tu-dresden.de> <52B479E1.7020204@gmail.com> <20131223131051.GB585@localhost.localdomain> In-Reply-To: <20131223131051.GB585@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/23/13, 8:10 AM, Frederic Weisbecker wrote: > On Fri, Dec 20, 2013 at 10:09:53AM -0700, David Ahern wrote: >> On 12/20/13, 5:27 AM, Joseph Schuchart wrote: >>> I know this comes late, but: As far as I can see, your change does not >>> preserve the logic of the code I suggested. The idea was to first gather >>> all the maximum timestamps of all cpus (that is, the last timestamp seen >>> on each cpu) and then determine the minimum of these maxima. These are >>> two distinct steps that I think cannot be combined in one update. Your >> >> A number of people have reported similar problems -- timestamps >> below last flush time. This approach would solve that problem for >> data processed from files, so it would be a good improvement. > > Could it be near what you're looking for? > > https://lkml.org/lkml/2012/2/18/53 > Forgot about that patch. It is similar to what Joseph wants for analyzing a file. I was carrying that patch while working on perf-kvm-stat-live last Fall. It does not solve the problem for live commands, so ended up dropping it and going with local (to the command) hacks. I still think for live commands getting a perf_clock timestamp at the start of a round and using that as the flush time will work best. David