From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752749AbYKMJo3 (ORCPT ); Thu, 13 Nov 2008 04:44:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751664AbYKMJoU (ORCPT ); Thu, 13 Nov 2008 04:44:20 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:43392 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751626AbYKMJoU (ORCPT ); Thu, 13 Nov 2008 04:44:20 -0500 Date: Thu, 13 Nov 2008 10:44:12 +0100 From: Ingo Molnar To: =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker Cc: Steven Rostedt , Linux Kernel Subject: Re: [PATCH 2/2] tracing/function-return-tracer: Call prepare_ftrace_return by registers Message-ID: <20081113094412.GL25479@elte.hu> References: <491B4F63.3090909@gmail.com> <20081112221623.GB6125@elte.hu> <20081113085949.GG25479@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00,DNS_FROM_SECURITYSAGE autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] 0.0 DNS_FROM_SECURITYSAGE RBL: Envelope sender in blackholes.securitysage.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Frédéric Weisbecker wrote: > 2008/11/13 Ingo Molnar : > > hm, function-exit is a quite bad name i think that tells nothing to > > the user. I like "function-cost tracer" because that tells the user > > what it's all about in the end. > > > > Or perhaps we could name it the "callgraph" tracer? (as opposed to the > > simpler function tracer which traces function entries) Note that we > > could use the output to build function call coverage graphs. > > But you can build a call graph with the function tracer, that what > does the script draw_trace.py in a bit loosely way for example. yes, but not reliably so - there's no guaranteed callgraph structure. With entry tracing we have entry+parent events, but especially across longer callchains there's no truly guaranteed way to preserve the full graph. > IMHO, function cost measurement or call graphs are particular uses > that can be made of this engine. You can also use it to trace > function return values for example. yes. The mockup output has place for that. > So perhaps naming it by thinking on the purpose it could be use at > most would be better that its "general" or "potential" purpose. I > don't know... i suggested "full-function" tracer name before, but that sounds a bit quirky too. Perhaps this should be the function-tracer, and the entry tracer would be the function-entry tracer? Ingo