Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755725Ab0ANMXh (ORCPT ); Thu, 14 Jan 2010 07:23:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755622Ab0ANMXh (ORCPT ); Thu, 14 Jan 2010 07:23:37 -0500 Received: from ey-out-2122.google.com ([74.125.78.25]:1574 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755580Ab0ANMXg (ORCPT ); Thu, 14 Jan 2010 07:23:36 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=SKZnrnod4+vP6t2V80AwOkRn5SqL4FX3sr3DhDwQ502c2lMkG2IgLTSoakpNla2DUw 3SN+vBSRqhy7lOLonXOmKbtwRgZmmA9/jYYvaWFHJcvrxUQRwrNJHDwHjzphiGCNoonz Exzta1sSCiSLx27rxyE2RS6EfL/vXXK11lnog= Date: Thu, 14 Jan 2010 13:23:31 +0100 From: Frederic Weisbecker To: Peter Zijlstra Cc: Srikar Dronamraju , Ingo Molnar , Arnaldo Carvalho de Melo , Ananth N Mavinakayanahalli , utrace-devel , Jim Keniston , Masami Hiramatsu , Maneesh Soni , Mark Wielaard , LKML Subject: Re: [RFC] [PATCH 7/7] Ftrace plugin for Uprobes Message-ID: <20100114122329.GC5033@nowhere> References: <20100111122521.22050.3654.sendpatchset@srikar.in.ibm.com> <20100111122608.22050.94088.sendpatchset@srikar.in.ibm.com> <1263468191.4244.300.camel@laptop> <20100114113509.GB5033@nowhere> <1263469381.4244.308.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1263469381.4244.308.camel@laptop> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1711 Lines: 51 On Thu, Jan 14, 2010 at 12:43:01PM +0100, Peter Zijlstra wrote: > On Thu, 2010-01-14 at 12:35 +0100, Frederic Weisbecker wrote: > > On Thu, Jan 14, 2010 at 12:23:11PM +0100, Peter Zijlstra wrote: > > > On Mon, 2010-01-11 at 17:56 +0530, Srikar Dronamraju wrote: > > > > This patch implements ftrace plugin for uprobes. > > > > > > Right, like others have said, trace events is a much saner interface. > > > > > > So the easiest way I can see that working is to register uprobes against > > > a file (not a pid). Then on creation it uses rmap to find all current > > > maps of that file and install the probe if there is a consumer for that > > > map. > > > > > > Then for each new mmap() of that file, we also need to check if there's > > > a consumer ready and install the probe. > > > > > > > > That looks racy. > > > > Say you first create a probe on /bin/ls: > > > > perf probe p addr_in_ls /bin/ls > > > > then something else launches /bin/ls behind you, probe > > is set on it > > > > then you launch: > > > > perf record -e "probe:...." /bin/ls > > > > Then it goes recording the previous instance. > > Uhm, why? Only the perf /bin/ls instance has a consumer and will thus > have a probe installed. > > (Or if you want to use ftrace you need to always have all instances > probed anyway) I see, so what you suggest is to have the probe set up as generic first. Then the process that activates it becomes a consumer, right? Would work, yeah. -- 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/