From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759823AbZAWKUK (ORCPT ); Fri, 23 Jan 2009 05:20:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753499AbZAWKT6 (ORCPT ); Fri, 23 Jan 2009 05:19:58 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:41256 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753480AbZAWKT5 (ORCPT ); Fri, 23 Jan 2009 05:19:57 -0500 Date: Fri, 23 Jan 2009 11:19:49 +0100 From: Ingo Molnar To: Frederic Weisbecker Cc: Steven Rostedt , Linux Kernel Mailing List Subject: Re: [PATCH 1/2 v2] tracing/function-graph-tracer: various fixes and features Message-ID: <20090123101949.GD15188@elte.hu> References: <497917b5.09cc660a.5f4c.ffffc568@mx.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <497917b5.09cc660a.5f4c.ffffc568@mx.google.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: 1.0 X-ELTE-SpamLevel: s X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=1.0 required=5.9 tests=BAYES_50 autolearn=no SpamAssassin version=3.2.3 1.0 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.4425] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Frederic Weisbecker wrote: > > This patch brings various bugfixes: > > _ Drop the first irrelevant task switch on the very beginning of a trace. > _ Drop the OVERHEAD word from the headers, the DURATION word is sufficient and will not > overlap other columns. > _ Make the headers fit well their respective columns whatever the selected options. > About features, one can now disable the duration (this will hide the > overhead too for convenient reasons and because on doesn't need overhead > if it hasn't the duration very nice! I've applied this to tip/tracing/function-graph-tracer, thanks Frederic! this: > I guess no one needs the nanosec precision here, the main goal is to > find when happened the events on a cpu when the trace switches from one > cpu to another. > > ie: > > 274.874760 | 1) 0.676 us | _spin_unlock(); > 274.874762 | 1) 0.609 us | native_load_sp0(); > 274.874763 | 1) 0.602 us | native_load_tls(); > 274.878739 | 0) 0.722 us | } > 274.878740 | 0) 0.714 us | native_pmd_val(); > 274.878741 | 0) 0.730 us | native_pmd_val(); > > Here there is a 4000 usecs difference when we switch the cpu. Still needs a solution - if we do cross-CPU traces we want to have a global trace clock with 'seemless' transition between CPUs. Ingo