From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757777AbcASJiU (ORCPT ); Tue, 19 Jan 2016 04:38:20 -0500 Received: from outbound-smtp07.blacknight.com ([46.22.139.12]:41114 "EHLO outbound-smtp07.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757321AbcASJiQ (ORCPT ); Tue, 19 Jan 2016 04:38:16 -0500 Date: Tue, 19 Jan 2016 09:38:12 +0000 From: Mel Gorman To: Jiri Olsa Cc: Jiri Olsa , Arnaldo Carvalho de Melo , LKML Subject: Re: perf stat stddev reporting broken since "perf stat: Introduce read_counters function" Message-ID: <20160119093812.GD10802@techsingularity.net> References: <20160118175946.GC10802@techsingularity.net> <20160119074228.GB20358@krava.brq.redhat.com> <20160119081623.GC20358@krava.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20160119081623.GC20358@krava.brq.redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 19, 2016 at 09:16:23AM +0100, Jiri Olsa wrote: > On Tue, Jan 19, 2016 at 08:42:28AM +0100, Jiri Olsa wrote: > > SNIP > > > > > > > Performance counter stats for 'sleep 1' (5 runs): > > > > > > 0.583178 task-clock (msec) # 0.001 CPUs utilized > > > 1 context-switches # 0.002 M/sec > > > 0 cpu-migrations # 0.000 K/sec > > > 67 page-faults # 0.141 M/sec > > > 1,224,416 cycles # 2.585 GHz > > > stalled-cycles-frontend > > > stalled-cycles-backend > > > 892,568 instructions # 0.68 insns per cycle > > > 184,975 branches # 390.554 M/sec > > > 8,512 branch-misses # 4.57% of all branches > > > > > > 1.000889249 seconds time elapsed ( +- 0.01% ) > > > > > > I checked and current master in Linus' tree is also broken. Is this > > > change in documented perf stat behaviour intentional? > > > > nope, not intentional.. I'll check on that, thanks for reporting > > for some reason we initialized the stat every iteration, > (the call is also wrong because it's called only over the > first res_stats[0]) > > attached patch works for me, could you please test? > I'll run more tests and put it in my queue > That works for me too, thanks. Feel free to put this on the patch; Tested-by: Mel Gorman When you send it through, can you make sure it has the following please? Cc: stable@vger.kernel.org # v4.2+ -- Mel Gorman SUSE Labs