Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761309AbZLJR5v (ORCPT ); Thu, 10 Dec 2009 12:57:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761038AbZLJR5s (ORCPT ); Thu, 10 Dec 2009 12:57:48 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:36318 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760962AbZLJR5r (ORCPT ); Thu, 10 Dec 2009 12:57:47 -0500 Date: Thu, 10 Dec 2009 18:57:37 +0100 From: Ingo Molnar To: "Frank Ch. Eigler" Cc: Steven Rostedt , Frederic Weisbecker , Tim Bird , Andrew Morton , Peter Zijlstra , Arnaldo Carvalho de Melo , Li Zefan , Thomas Gleixner , linux kernel Subject: Re: [PATCH 2/4] ftrace - add function_duration tracer Message-ID: <20091210175737.GB5256@elte.hu> References: <4B202778.4030801@am.sony.com> <20091210070800.GB16874@elte.hu> <20091210120332.GA5042@nowhere> <20091210141121.GB1436@elte.hu> <1260456803.2146.167.camel@gandalf.stny.rr.com> <20091210153845.GA28230@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 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 Content-Length: 1627 Lines: 44 * Frank Ch. Eigler wrote: > Ingo Molnar writes: > > > [...] > > Just off the top of my head we want to be able to trace: > > > > - max irq service latencies for a given IRQ > > - max block IO completion latencies for a app > > - max TLB flush latencies in the system > > - max sys_open() latencies in a task > > - max fork()/exit() latencies in a workload > > - max scheduling latencies on a given CPU > > - max page fault latencies > > - max wakeup latencies for a given task > > - max memory allocation latencies > > > > - ... and dozens and dozens of other things where there's a "start" > > and a "stop" event and where we want to measure the time between > > them. > > [...] > > FWIW, those who want to collect such measurements today can do so with > a few lines of systemtap script for each of the above. Well, i dont think stap can do workload instrumentation. It can do system-wide (and user local / task local) - but can it do per task hierarchies? Also, i dont think stap supports proper separation of per workload measurements either. I.e. can you write a script that will work properly even if multiple monitoring tools are running, each trying to measure latencies? Also, i personally find built-in kernel functionality more trustable than dynamically built stap kernel modules that get inserted. 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/