Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752057Ab3HUNj5 (ORCPT ); Wed, 21 Aug 2013 09:39:57 -0400 Received: from mail-oa0-f43.google.com ([209.85.219.43]:62579 "EHLO mail-oa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751995Ab3HUNj4 (ORCPT ); Wed, 21 Aug 2013 09:39:56 -0400 MIME-Version: 1.0 In-Reply-To: <520B7F6D.2000004@intel.com> References: <1376484517-5339-1-git-send-email-adrian.hunter@intel.com> <1376484517-5339-10-git-send-email-adrian.hunter@intel.com> <520B7F6D.2000004@intel.com> Date: Wed, 21 Aug 2013 15:39:55 +0200 Message-ID: Subject: Re: [PATCH V11 09/15] perf: make events stream always parsable From: Stephane Eranian To: Adrian Hunter Cc: Arnaldo Carvalho de Melo , LKML , David Ahern , Frederic Weisbecker , Jiri Olsa , Mike Galbraith , Namhyung Kim , Paul Mackerras , Peter Zijlstra , Ingo Molnar Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1699 Lines: 35 On Wed, Aug 14, 2013 at 3:00 PM, Adrian Hunter wrote: > On 14/08/13 15:48, Adrian Hunter wrote: >> The event stream is not always parsable because the format of a sample >> is dependent on the sample_type of the selected event. When there >> is more than one selected event and the sample_types are not the >> same then parsing becomes problematic. A sample can be matched to its >> selected event using the ID that is allocated when the event is opened. >> Unfortunately, to get the ID from the sample means first parsing it. >> >> This patch adds a new sample format bit PERF_SAMPLE_IDENTIFER that puts >> the ID at a fixed position so that the ID can be retrieved without >> parsing the sample. For sample events, that is the first position >> immediately after the header. For non-sample events, that is the last >> position. >> >> In this respect parsing samples requires that the sample_type and ID >> values are recorded. For example, perf tools records struct perf_event_attr >> and the IDs within the perf.data file. Those must be read first >> before it is possible to parse samples found later in the perf.data file. >> >> Signed-off-by: Adrian Hunter > > Forgot to add Peter's ack which is here: > > http://marc.info/?l=linux-kernel&m=137629757013526&w=2 Tested this patch via libpfm4 and per-event branch-stack. Works well. Tested-by: Stephane Eranian -- 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/