From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761417AbZBYJMj (ORCPT ); Wed, 25 Feb 2009 04:12:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756668AbZBYJMU (ORCPT ); Wed, 25 Feb 2009 04:12:20 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:40326 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752597AbZBYJMT (ORCPT ); Wed, 25 Feb 2009 04:12:19 -0500 Date: Wed, 25 Feb 2009 10:10:41 +0100 From: Ingo Molnar To: Pekka Enberg Cc: Andrew Morton , Steven Rostedt , LKML , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Theodore Tso , Arjan van de Ven , Pekka Paalanen , Arnaldo Carvalho de Melo , Jason Baron , Martin Bligh , Mathieu Desnoyers , "Frank Ch. Eigler" , KOSAKI Motohiro , Jens Axboe , Masami Hiramatsu , Steven Rostedt Subject: Re: [PATCH 2/4] tracing: add event trace infrastructure Message-ID: <20090225091041.GB30940@elte.hu> References: <20090225025608.956691460@goodmis.org> <20090225025753.798204550@goodmis.org> <20090224194548.3effb746.akpm@linux-foundation.org> <20090224203308.8d623e0b.akpm@linux-foundation.org> <20090225081118.GC15303@elte.hu> <20090225002852.5ef5b869.akpm@linux-foundation.org> <84144f020902250100k41e55dd7w8a9c8d2ca96908ea@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <84144f020902250100k41e55dd7w8a9c8d2ca96908ea@mail.gmail.com> 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 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Pekka Enberg wrote: > Hi Andrew, > > On Wed, Feb 25, 2009 at 10:28 AM, Andrew Morton > wrote: > > A better approach would be to design simple, robust kernel interfaces > > which make sense and which aren't made all complex by putting the user > > interface in kernel space.  And to maintain corresponding userspace > > tools which manipulate and present the IO from those kernel interfaces. > > We did this for kmemtrace and quite frankly, I usually end up > spending more time figuring out how to export the data from a > virtual machine than actually analyzing the results. What > makes ftrace so cool is the fact that it has almost > zero-overhead for setup and that the text-based data format > plays well with simple scripting tools available everywhere. I just tried to write a similar reply - and ended up with a long 5 page mail which was just repeating points others and me made before. Instead i'll now print out your reply and will hang it on the wall ... ;-) Ingo