From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754891AbZHFL2c (ORCPT ); Thu, 6 Aug 2009 07:28:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753342AbZHFL2c (ORCPT ); Thu, 6 Aug 2009 07:28:32 -0400 Received: from viefep12-int.chello.at ([62.179.121.32]:20205 "EHLO viefep12-int.chello.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752828AbZHFL2b (ORCPT ); Thu, 6 Aug 2009 07:28:31 -0400 X-SourceIP: 213.93.53.227 Subject: Re: malloc() tracing in perf? From: Peter Zijlstra To: "Frank Ch. Eigler" Cc: Pekka Enberg , Ingo Molnar , acme , Steven Rostedt , =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Eduard-Gabriel Munteanu , roland , Christoph Hellwig , Masami Hiramatsu , Mathieu Desnoyers , linux-kernel@vger.kernel.org In-Reply-To: <20090806112059.GD18768@redhat.com> References: <4A7A8ADD.4080208@cs.helsinki.fi> <1249546610.32113.35.camel@twins> <20090806112059.GD18768@redhat.com> Content-Type: text/plain Date: Thu, 06 Aug 2009 13:28:14 +0200 Message-Id: <1249558094.32113.242.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2009-08-06 at 07:20 -0400, Frank Ch. Eigler wrote: > Hi - > > On Thu, Aug 06, 2009 at 10:16:50AM +0200, Peter Zijlstra wrote: > > [...] > > > But then it hit me, why can't I have kmemtrace + perf but for > > > user-space? Something like the "Malloc Trace" shown here: > > > [...] > > > I seem to have heard people are working on such a thing, but I can't > > seem to find a single LKML post with 'uprobe' in the subject in the > > past two years [...] > > That work is ongoing, and being discussed on utrace-devel@redhat.com, > since it is a prerequisite. Still hiding the discussion and the design never helped anybody. You might think it ready and then post it to LKML only to have it ripped apart -- have the discussion openly please. > > Now doing probes on userspace is hard because you need to know more > > about the userspace bits than a kernel really ought to be interested > > in. [...] Anyway, like you say, it has uses (potentially very > > powerful ones), Sun/Apple do it with Dtrace, Linux wants it but I > > don't think we quite agreed on how to do it :-) > > While these deliberations are ongoing, you can use systemtap. Probing > random places in userspace is about as casual as probing the kernel: Right, but that still doesn't tell us anything on how you're doing that, does it?