From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757532Ab0KJXrO (ORCPT ); Wed, 10 Nov 2010 18:47:14 -0500 Received: from www.tglx.de ([62.245.132.106]:56654 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757325Ab0KJXrK (ORCPT ); Wed, 10 Nov 2010 18:47:10 -0500 Date: Thu, 11 Nov 2010 00:45:59 +0100 (CET) From: Thomas Gleixner To: Steven Rostedt cc: Mathieu Desnoyers , "Luck, Tony" , Frederic Weisbecker , Ingo Molnar , Peter Zijlstra , "linux-kernel@vger.kernel.org" , "Huang, Ying" , "bp@alien8.de" , "akpm@linux-foundation.org" , "mchehab@redhat.com" , Arnaldo Carvalho de Melo , Arjan van de Ven Subject: Re: Tracing Requirements (was: [RFC/Requirements/Design] h/w error reporting) In-Reply-To: <1289431227.12418.211.camel@gandalf.stny.rr.com> Message-ID: References: <1289401781.12418.145.camel@gandalf.stny.rr.com> <1289403019.2084.17.camel@laptop> <20101110174852.GB4001@elte.hu> <1289412329.12418.177.camel@gandalf.stny.rr.com> <1289413460.2084.27.camel@laptop> <20101110184105.GH22410@elte.hu> <1289415645.12418.180.camel@gandalf.stny.rr.com> <20101110191127.GA6190@nowhere> <20101110202316.GA32396@Krystal> <987664A83D2D224EAE907B061CE93D5301649A71DC@orsmsx505.amr.corp.intel.com> <20101110225115.GB9299@Krystal> <1289431227.12418.211.camel@gandalf.stny.rr.com> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 10 Nov 2010, Steven Rostedt wrote: > On Thu, 2010-11-11 at 00:12 +0100, Thomas Gleixner wrote: > > > Cramming both into the same session is just insane. > > That just doubled the overhead of the tracer. > > > > > The first rule is "Keep It Simple!". Period. > > It's not that complex. Both Mathieu and I have implemented it. Really, > I've seen a lot more complex code. Just because it does not fit into the > CS101 course does not mean that it is totally complex. I know you have implemented it and it's not about CS101, it's about the insanity of what we have in the ftrace ringbuffer code. It does not fulfil in any way the "Keep it Simple" requirement. Period. And as I said earlier on IRC, you are trying to create the ZeroImpactFilteringMultiSessionFlightRecorderOverwriteFifoSplicePerfMmapTracer which is a nice wet dream, but completely unrealistic to achieve in one go. When I yelled at you folks in Boston last week and suggested to come up with a syscall for buffers and the corresponding configuration interfaces along with a unified record format, then I certainly did not ask for the ZIFMSFROFSPMT thingy and a rewrite the world approach. I told you back in 2008 that you need to think hard about the interfaces and start with a reasonable simple implementation. Then proceed from there. The overall achievement so far is an ongoing ringbuffer pissing contest, zero interfaces and lenghty explanations which kind of tracer madness is preferred by whom. I don't call this progress. If you did not get the message last week, then you have it in writing now to digest as long as it takes: Get your gear together and come up with sensible gradual approaches which bring us to a better progress ratio than 0/year. Thanks, tglx