From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Olsa Subject: Re: Two questions on perf dwarf callchains Date: Wed, 29 Jan 2014 12:18:44 +0100 Message-ID: <20140129111844.GA1869@krava.brq.redhat.com> References: <1389954083.1125.23.camel@nb-andreolini.mat.unimo.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx1.redhat.com ([209.132.183.28]:51770 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751002AbaA2LSr (ORCPT ); Wed, 29 Jan 2014 06:18:47 -0500 Content-Disposition: inline In-Reply-To: <1389954083.1125.23.camel@nb-andreolini.mat.unimo.it> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Mauro Andreolini Cc: linux-perf-users@vger.kernel.org On Fri, Jan 17, 2014 at 11:21:23AM +0100, Mauro Andreolini wrote: > Hi all, hi > > No kallsyms or vmlinux with build-id 4c6ab941f31dde04c2a481430218994849927c8d was found > [ext4] with build id 4c6ab941f31dde04c2a481430218994849927c8d not found, continuing without symbols > No kallsyms or vmlinux with build-id 21f163b0a8a8b924efdd173b8f83ad723d378958 was found > [drm] with build id 21f163b0a8a8b924efdd173b8f83ad723d378958 not found, continuing without symbols > No kallsyms or vmlinux with build-id d0bd7dd69886c2dccde18dee760b6d39cc0b5a55 was found[qxl] with build id d0bd7dd69886c2dccde18dee760b6d39cc0b5a55 not found, continuing without symbols > No kallsyms or vmlinux with build-id 8d13e6f0c4d4f8b4628c8c4bd6c660b0a00576df was found[ttm] with build id 8d13e6f0c4d4f8b4628c8c4bd6c660b0a00576df not found, continuing without symbols hum, do you have kernel-debuginfo* packages installed? SNIP > > Problem n.2: sometimes perf prints bogus callchains (in particular > when the various printf() variants are involved). > > |--1.46%-- 0xffffffffa048a275 > | 0xffffffffa048c110 > | 0xffffffffa04909e7 > | | > | |--80.00%-- 0xffffffffa0490afa > | | 0xffffffffa048ee8b > | | 0xffffffffa048ba8f > | | bit_bmove > | | fbcon_redraw_blit.isra.22 > | | fbcon_scroll > | | scrup > | | lf > | | do_con_trol > | | do_con_write.part.18 > | | con_write > | | do_output_char > | | n_tty_write > | | tty_write > | | vfs_write > | | sys_write > | | system_call_fastpath > | | __GI___libc_write > | | | > | | |--50.00%-- vfprintf > | | | 0x0 <---HERE > | | | > | | |--25.00%-- main > | | | __libc_start_main > | | | _start > | | | 0x0 <---HERE > | | | > | | --25.00%-- 0x7facc1df12a0 HERE this one could be caused by: http://marc.info/?l=linux-kernel&m=134934717011451&w=2 I never managed to push this change through.. need to revisit it ;-) if you want to try, I rebased the patch and put it in here: git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git branch perf/rsp_fix1 commit: https://git.kernel.org/cgit/linux/kernel/git/jolsa/perf.git/commit/?h=perf/rsp_fix1&id=5eed39431f9b1e65e740a2e3e197c79f0a1bcf6b it still fixies some of the backtraces for me jirka