From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756703Ab2GYMLg (ORCPT ); Wed, 25 Jul 2012 08:11:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53658 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756630Ab2GYMLe (ORCPT ); Wed, 25 Jul 2012 08:11:34 -0400 Date: Wed, 25 Jul 2012 14:11:21 +0200 From: Jiri Olsa To: David Ahern Cc: acme@ghostprotocols.net, linux-kernel@vger.kernel.org, Ingo Molnar , Namhyung Kim , Frederic Weisbecker , Peter Zijlstra Subject: Re: [PATCH 04/11] perf kvm: fix bug resolving guest kernel syms - v2 Message-ID: <20120725121121.GB946@krava.brq.redhat.com> References: <1342826756-64663-1-git-send-email-dsahern@gmail.com> <1342826756-64663-5-git-send-email-dsahern@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1342826756-64663-5-git-send-email-dsahern@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 20, 2012 at 05:25:49PM -0600, David Ahern wrote: > Guest kernel symbols are not resolved despite passing the information > needed to resolve them. e.g., > > perf kvm --guest --guestmount=/tmp/guest-mount record -a -- sleep 1 > perf kvm --guest --guestmount=/tmp/guest-mount report --stdio > > 36.55% [guest/11399] [unknown] [g] 0xffffffff81600bc8 > 33.19% [guest/10474] [unknown] [g] 0x00000000c0116e00 > 30.26% [guest/11094] [unknown] [g] 0xffffffff8100a288 > 43.69% [guest/10474] [unknown] [g] 0x00000000c0103d90 > 37.38% [guest/11399] [unknown] [g] 0xffffffff81600bc8 > 12.24% [guest/11094] [unknown] [g] 0xffffffff810aa91d > 6.69% [guest/11094] [unknown] [u] 0x00007fa784d721c3 > > which is just pathetic. > > After a maddening 2 days sifting through perf minutia I found it -- > id_hdr_size is not initialized for guest machines. This shows up on the > report side as random garbage for the cpu and timestamp, e.g., > > 29816 7310572949125804849 0x1ac0 [0x50]: PERF_RECORD_MMAP ... > > That messes up the sample sorting such that synthesized guest maps are > processed last. > > With this patch you get a much more helpful report: > > 12.11% [guest/11399] [guest.kernel.kallsyms.11399] [g] irqtime_account_process_tick > 10.58% [guest/11399] [guest.kernel.kallsyms.11399] [g] run_timer_softirq > 6.95% [guest/11094] [guest.kernel.kallsyms.11094] [g] printk_needs_cpu > 6.50% [guest/11094] [guest.kernel.kallsyms.11094] [g] do_timer > 6.45% [guest/11399] [guest.kernel.kallsyms.11399] [g] idle_balance > 4.90% [guest/11094] [guest.kernel.kallsyms.11094] [g] native_read_tsc > ... > > v2: > - changed rbtree walk to use rb_first per Namhyung's suggestion > > Signed-off-by: David Ahern > Cc: Arnaldo Carvalho de Melo > Cc: Ingo Molnar > Cc: Jiri Olsa Tested-by: Jiri Olsa