From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnaldo Carvalho de Melo Subject: Re: [PATCH 3/3] perf events: add timehist option to record and report Date: Sat, 19 Feb 2011 12:38:25 -0200 Message-ID: <20110219143825.GA2729@ghostprotocols.net> References: <1298008433-22911-1-git-send-email-daahern@cisco.com> <1298008433-22911-4-git-send-email-daahern@cisco.com> <20110218070657.GA11404@elte.hu> <4D5E8204.2090501@cisco.com> <20110218175926.GA3445@nowhere> <4D5EB564.6030504@cisco.com> <1298054399.5226.779.camel@laptop> <4D5EBE2C.7000701@cisco.com> <20110219093216.GA30331@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-yw0-f46.google.com ([209.85.213.46]:45878 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754368Ab1BSOid (ORCPT ); Sat, 19 Feb 2011 09:38:33 -0500 Content-Disposition: inline In-Reply-To: <20110219093216.GA30331@elte.hu> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Ingo Molnar Cc: David Ahern , Peter Zijlstra , Frederic Weisbecker , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, paulus@samba.org, Thomas Gleixner Em Sat, Feb 19, 2011 at 10:32:16AM +0100, Ingo Molnar escreveu: > * David Ahern wrote: > > > On 01/23/11 at 03:45:67 a syslog event noted an application restart. > > Checking the applications logs it went silent. Why? What does perf say? > > > > Oh, 2 days have gone by before said event is reported to engineering, > > and the server was been rebooted to 'clear' the problem - hence > > resetting monotonic clock. > > I think that's a valid usecase and the feature you are suggestion is very useful. > > Why not extend the regular trace output to also (optionally) output GTOD timestamps? That is how this this feature request/submission originally started. David tried with an extra header, then a synthesized event, then after some discussion with Peter I started working on a monotonic clock event, but got sidetracked with other stuff, he tried picking up from where I left and here we are. I think the summary is: we need a clock_gettime like interface so that users can pick and choose what clock matches best whatever app they're trying to merge logs. - Arnaldo