Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756682AbZKEI2H (ORCPT ); Thu, 5 Nov 2009 03:28:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755728AbZKEI2F (ORCPT ); Thu, 5 Nov 2009 03:28:05 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:35913 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756026AbZKEI2E (ORCPT ); Thu, 5 Nov 2009 03:28:04 -0500 Date: Thu, 5 Nov 2009 09:27:33 +0100 From: Ingo Molnar To: Masami Hiramatsu Cc: Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo , Ananth N Mavinakayanahalli , Christoph Hellwig , "Frank Ch. Eigler" , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , "H. Peter Anvin" , Jason Baron , Jim Keniston , "K. Prasad" , Peter Zijlstra , Roland McGrath , Srikar Dronamraju , Steven Rostedt Subject: Re: [PATCH 1/1] perf symbols: Use the buildids if present Message-ID: <20091105082733.GA18011@elte.hu> References: <1257367843-26224-1-git-send-email-acme@infradead.org> <4AF24681.1060504@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AF24681.1060504@redhat.com> User-Agent: Mutt/1.5.19 (2009-01-05) X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.5 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2745 Lines: 67 * Masami Hiramatsu wrote: > Arnaldo Carvalho de Melo wrote: >> From: Arnaldo Carvalho de Melo >> >> Now 'perf record' will intercept PERF_RECORD_MMAP calls, creating a >> linked list of DSOs, then when the session finishes, it will traverse >> this list and read the buildids, stashing them at the end of the file >> and will set up a new feature bit in the header bitmask. >> >> 'perf report' will then notice this feature and populate the 'dsos' list >> and set the build ids. >> >> When reading the symtabs it will refuse to load from a file that doesn't >> have the same build id. >> >> Example: >> >> [root@doppio ~]# perf report | head >> /home/acme/bin/perf with build id b1ea544ac3746e7538972548a09aadecc5753868 not found, continuing without symbols >> # Samples: 2621434559 >> # >> # Overhead Command Shared Object Symbol >> # ........ ............... ............................. ...... >> # >> 7.91% init [kernel] [k] read_hpet >> 7.64% init [kernel] [k] mwait_idle_with_hints >> 7.60% swapper [kernel] [k] read_hpet >> 7.60% swapper [kernel] [k] mwait_idle_with_hints >> 3.65% init [kernel] [k] 0xffffffffa02339d9 >> [root@doppio ~]# >> >> In this case the 'perf' binary was an older one, vanished, so it the symbols >> probably wouldn't match. >> >> Next patches will support the kernel as well, reading the build id notes for it >> and the modules from /sys. > > Great! then I can use it on 'perf probe' to check the dwarf binary is > same as running kernel. > >> Another patch should also introduce a new plumbing command: >> >> 'perf list-buildids' >> >> that will then be used in porcelain that is distro specific to >> fetch -debuginfo packages where such buildids are present. This will in turn >> allow for one to run 'perf record' in one machine and 'perf report' in another. > > Hmm, so, will this command list up all debuginfo files with buildids? > If so, can it also find a kernel binary built locally? Arnaldo, how about adding the kernel binary's build path to /sys/kernel/notes, during the kernel build? (With perhaps a .config override as well, for package builds.) That object might or might not exist, and if it does not exist, or if there is a buildid mismatch, we can fall back to 'well known' places for kernel/module binaries. 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/