Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754739AbZKTRwg (ORCPT ); Fri, 20 Nov 2009 12:52:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753678AbZKTRwg (ORCPT ); Fri, 20 Nov 2009 12:52:36 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:49122 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753443AbZKTRwf (ORCPT ); Fri, 20 Nov 2009 12:52:35 -0500 Date: Fri, 20 Nov 2009 15:52:28 -0200 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: Li Zefan , Pekka Enberg , Frederic Weisbecker , Steven Rostedt , Peter Zijlstra , Eduard - Gabriel Munteanu , LKML , "linux-mm@kvack.org" 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> X-Url: http://oops.ghostprotocols.net:81/blog User-Agent: Mutt/1.5.19 (2009-01-05) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1797 Lines: 39 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 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/