Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932241AbWIPAFP (ORCPT ); Fri, 15 Sep 2006 20:05:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932243AbWIPAFP (ORCPT ); Fri, 15 Sep 2006 20:05:15 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:4534 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S932241AbWIPAFN (ORCPT ); Fri, 15 Sep 2006 20:05:13 -0400 Date: Sat, 16 Sep 2006 01:57:07 +0200 From: Ingo Molnar To: Nicholas Miell Cc: Roman Zippel , Thomas Gleixner , karim@opersys.com, Andrew Morton , Paul Mundt , Jes Sorensen , Mathieu Desnoyers , linux-kernel@vger.kernel.org, Christoph Hellwig , Ingo Molnar , Greg Kroah-Hartman , Tom Zanussi , ltt-dev@shafik.org, Michel Dagenais Subject: Re: [PATCH 0/11] LTTng-core (basic tracing infrastructure) 0.5.108 Message-ID: <20060915235707.GB29929@elte.hu> References: <1158348954.5724.481.camel@localhost.localdomain> <450B0585.5070700@opersys.com> <1158351780.5724.507.camel@localhost.localdomain> <20060915204812.GA6909@elte.hu> <20060915215112.GB12789@elte.hu> <20060915231419.GA24731@elte.hu> <1158364161.2352.9.camel@entropy> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1158364161.2352.9.camel@entropy> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -2.9 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.9 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.5 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5000] -0.1 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1571 Lines: 37 * Nicholas Miell wrote: > You're going to want to be able to trace every function in the kernel, > which means they'd all need a __trace -- and in that case, a > -fpad-functions-for-tracing gcc option would make more sense then > per-function attributes. the __trace attribute would be a _specific_ replacement for a _specific_ static markup at the entry of a function. So no, we would not want to add __trace to _every_ function in the kernel: only those which get commonly traced. And note that SystemTap can trace the rest too, just with slighly higher overhead. In that sense __trace is not an enabling infrastructure, it's a performance tuning infrastructure. > The option could also insert NOPs before RETs, not just before the > prologue so that function returns are equally easy to trace. (It might > also inhibit tail calls, assuming being able to trace all function > returns is more important than that optimization.) yeah. __trace_entry and __trace_exit [or both] attributes. Makes sense. > And SystemTap can already hook into sock_sendmsg() (or any other > function) and examine it's arguments -- all of this GCC extension talk > is just performance enhancement. yes, yes, yes, exactly!!! Finally someone reads my mails and understands my points. There's hope! ;) Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/