From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id BF32F6B004D for ; Fri, 20 Nov 2009 12:52:40 -0500 (EST) Date: Fri, 20 Nov 2009 15:52:28 -0200 From: Arnaldo Carvalho de Melo Subject: Re: [RFC][PATCH 1/2] perf: Add 'perf kmem' tool Message-ID: <20091120175228.GD27926@ghostprotocols.net> References: <4B064AF5.9060208@cn.fujitsu.com> <20091120081440.GA19778@elte.hu> <84144f020911200019p4978c8e8tc593334d974ee5ff@mail.gmail.com> <20091120083053.GB19778@elte.hu> <4B0657A4.2040606@cs.helsinki.fi> <4B06590C.7010109@cn.fujitsu.com> <20091120090353.GE19778@elte.hu> <20091120144215.GH18283@ghostprotocols.net> <20091120164110.GA24183@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091120164110.GA24183@elte.hu> Sender: owner-linux-mm@kvack.org To: Ingo Molnar Cc: Li Zefan , Pekka Enberg , Frederic Weisbecker , Steven Rostedt , Peter Zijlstra , Eduard - Gabriel Munteanu , LKML , "linux-mm@kvack.org" List-ID: Em Fri, Nov 20, 2009 at 05:41:10PM +0100, Ingo Molnar escreveu: > > So we have a mechanism that is already present in several distros > > (build-id), that is in the kernel build process since ~2.6.23, and that > > avoids using mismatching DSOs when resolving symbols. > > But what do we do if we have another box that runs say on a MIPS CPU, > uses some minimal distro - and copy that perf.data over to an x86 box. There would be no problem, it would be just a matter of installing the right -debuginfo packages, for MIPS. Or the original, unstripped FS image sent to the machine with the MIPS cpu, if there aren't -debuginfo packages. Either one, the right DSOs would be found by the buildids. There are other scenarios, like a binary that gets updated while a long running perf record session runs, the way to differentiate between the two DSOs wouldn't be the name, but the buildid. > The idea is there to be some new mode of perf.data where all the > relevant DSO contents (symtabs but also sections with instructions for > perf annotate to work) are copied into perf.data, during or after data > capture - on the box that does the recording. > > Once we have everything embedded in the perf.data, analysis passes only > have to work based on that particular perf.data - no external data. Well, we can that, additionally, but think about stripped binaries, we would lose potentially a lot because the symtabs on that small machine would have poorer symtabs than the ones in an unstriped binary (or in a -debuginfo package). - Arnaldo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org