From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751081AbdEaVJ2 (ORCPT ); Wed, 31 May 2017 17:09:28 -0400 Received: from semfq01.mfg.siteprotect.com ([64.26.60.182]:35494 "EHLO semfq01.mfg.siteprotect.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751000AbdEaVJ0 (ORCPT ); Wed, 31 May 2017 17:09:26 -0400 Date: Wed, 31 May 2017 17:08:59 -0400 (EDT) From: Vince Weaver X-X-Sender: vince@pianoman.cluster.toy To: Peter Zijlstra cc: Andi Kleen , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Stephane Eranian , Alexander Shishkin , Arnaldo Carvalho de Melo , Jiri Olsa Subject: Re: perf group read for inherited events In-Reply-To: <20170530185300.ej763qvmsw5aldhg@hirez.programming.kicks-ass.net> Message-ID: References: <20170526205601.GA5271@tassilo.jf.intel.com> <20170530094512.dy2nljns2uq7qa3j@hirez.programming.kicks-ass.net> <20170530135714.GJ24144@tassilo.jf.intel.com> <20170530170150.cx554x7nmbrzv7nc@hirez.programming.kicks-ass.net> <20170530185300.ej763qvmsw5aldhg@hirez.programming.kicks-ass.net> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Originating-IP: 64.26.60.144 X-SpamExperts-Domain: hostwaytestmfg.com X-SpamExperts-Username: 64.26.60.144/30 Authentication-Results: mfg.siteprotect.com; auth=pass smtp.auth=64.26.60.144/30@hostwaytestmfg.com X-SpamExperts-Outgoing-Class: ham X-SpamExperts-Outgoing-Evidence: SB/global_tokens (0.00466272748779) X-Recommended-Action: accept X-Filter-ID: s0sct1PQhAABKnZB5plbIZI2LH29AsuM4TsCPQ0vJ/KtnDbhsDtLos9bWjuA0y73Pg+QrxY6gq7D fa72IS1maIqPuKEgMyfBW022v5adAIlR7gKuJOz6hvTOYnc+46Eet4lP0GR8jfSinTz1pajzuyEb xxLK3QENjMlUnGz2Ts/0gG1hPdLzTaFExS1OwEYjG1jNTo7prMIsiwedh0XXVWDV88RyIP3Z/ugs w79W/v1m4zuNRcgRKiGg7nXFaZTx2B4cyavYByCDIrGB4AiivDa54X7NDQdCrusTtKstkOSTJZHV Q843cFe33i1fsUekT0RQPBMJ9tK+MUeAepXrrQvOyDEqSAXOZUizIyP3vjQdxk1T1rVpnJ/TmIoU Wx0G72fnF2uEjzDLLyL0NObZ/C/nvx8LppikJvKEsVBRnmok4Ndu06h2Q8QP5GQeNUYflVNBaAXX saBm5MwURYe8uc9QMYWgwLNGIAFhfV8d/usQQeK5qlAG+woRW+D4rhlkaZcLF2fTvXJeVF6TV53t HVyXZSdgIUgeuaJEDiNYFY41L2BCjmuu+A8N5iObUIKGidKaNO3e5seKdxvZHxxxAYOoT5f9zNwj lArtXM+EHVIO+g74mld0gKAHrVBDjoRzOIC5tVKTOIfrOHhSUO0PTJK26BeeacqgL3zj/T0YhZOu FRRhxi+muAIr9B6Z/rL5VoFlrH85nRAcZP8OPs9l1vKVGSLuj9DXGsUWwvqOKITbt1e1b/UOn4W+ pGG3F3eLOnLVDfnAkYJZVF/3BKFU4RjDkgHw6Yt/5N28Wb0VLOd0NoRILEegs8sFpdNUCUuStGfj F6RxkG/nQ6sQOEj8lSyjxUXbxlc+hWrYZDq70lXFI+MLRf6e3nrQvQgroVaKx2r8YfOV0YJl9JVB km7JeCQYQv8AW5lEPXFsFVjtM4GGGWUvw1ASwOZxjenCJ9c/jpXAWX2jXcyp6owTDRb/+8GR39PC wrPgAfwKpFLVNcOfbO96r2VMfvmfuwyWTnnBagRc0p+cJuvCpfQamYLO6sKt9+MHCUigiU7g43wm 9HLpyiM2ZpLzq1HhjcfywaX6dSmeixTuI/sZqW8uHn+M9ec97M9InMfTuoXigHW7HPlwn9LVzZX5 NxrjoDqao8l87uDjV/sFUXQr+CDrNQuIHmU1PMV382d9nr/Sqz9xuQIUeLrZz7zvqjG0GLqTHFj3 X-Report-Abuse-To: spam@semfq02.mfg.siteprotect.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 30 May 2017, Peter Zijlstra wrote: > On Tue, May 30, 2017 at 01:55:33PM -0400, Vince Weaver wrote: > > So the issue is currently if you were sampling, and you were sampling on > > an event group, and you had set PERF_SAMPLE_READ to get all counts for a > > group, and the event was also inherited.... > > No, anything PERF_SAMPLE_READ (group or not) on inherited events is > wrong. ah, yes. I should fix the wording in the manpage as it's a bit confusing. > > perf_event_open() would let > > you do this even though the results would probably be wrong? > > Right, currently we have the filter on PERF_FORMAT_GROUP, but it should > be PERF_SAMPLE_READ. > > So a !group SAMPLE_READ on inherited is currently allowed but returns > 'interesting' values. I'm not aware of anything that will break on fixing this. Especially if we are always returning bad results then it would be better to break things so we find people (if any) who are depending on the wrong results. Vince