Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753378Ab0KYOCK (ORCPT ); Thu, 25 Nov 2010 09:02:10 -0500 Received: from casper.infradead.org ([85.118.1.10]:41766 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752490Ab0KYOCI convert rfc822-to-8bit (ORCPT ); Thu, 25 Nov 2010 09:02:08 -0500 Subject: Re: [RFC PATCHv3] perf tools: add event grouping capability to "perf stat" From: Peter Zijlstra To: Stephane Eranian Cc: Corey Ashford , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , Frederic Weisbecker , Julia Lawall , Tom Zanussi , linux-kernel@vger.kernel.org, Matt Fleming In-Reply-To: References: <1290650053-3486-1-git-send-email-cjashfor@linux.vnet.ibm.com> <1290666760.2072.539.camel@laptop> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Thu, 25 Nov 2010 15:02:00 +0100 Message-ID: <1290693720.2145.34.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1075 Lines: 25 On Thu, 2010-11-25 at 14:19 +0100, Stephane Eranian wrote: > I think using PERF_SAMPLE_READ may expose a problem in the > perf.data format. To correctly parse a sample created with SAMPLE_READ, > you need to know the attr.read_format. But for that you need to know the > event which caused the sample, but for that you need the SAMPLE_ID, > and you don't know if it's there or not. In other words, there is a chicken > and egg problem. > > I think the issue is that PERF_RECORD_SAMPLE is missing a mandatory > piece of information: overflow event ID. This must a mandatory field, not > optional as it is today. It is okay when you have only one group, but we'd > like to go beyond that. I'm not sure I get it, there's both PERF_FORMAT_ID and PERF_SAMPLE_ID, so afaict there's a working combination for what you want to do. -- 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/