Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754728Ab3GATKl (ORCPT ); Mon, 1 Jul 2013 15:10:41 -0400 Received: from mail-oa0-f47.google.com ([209.85.219.47]:43986 "EHLO mail-oa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751889Ab3GATKj convert rfc822-to-8bit (ORCPT ); Mon, 1 Jul 2013 15:10:39 -0400 MIME-Version: 1.0 In-Reply-To: <51D1D043.5030509@gmail.com> References: <1372319707-13892-1-git-send-email-adrian.hunter@intel.com> <1372319707-13892-13-git-send-email-adrian.hunter@intel.com> <51CC6AAF.4030404@gmail.com> <51D14CB6.206@intel.com> <51D1D043.5030509@gmail.com> Date: Mon, 1 Jul 2013 21:10:38 +0200 Message-ID: Subject: Re: [PATCH V2 12/15] perf tools: allow non-matching sample types From: Stephane Eranian To: David Ahern Cc: Adrian Hunter , Arnaldo Carvalho de Melo , LKML , Frederic Weisbecker , Jiri Olsa , Mike Galbraith , Namhyung Kim , Paul Mackerras , Peter Zijlstra Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1745 Lines: 32 On Mon, Jul 1, 2013 at 8:53 PM, David Ahern wrote: > > On 7/1/13 3:32 AM, Adrian Hunter wrote: >> >> Snip >> >>> >>> While this works for a combined S/W and tracepoint events session, I do not >>> like promoting sample types to the minimum compatible level for all events >>> in the session. perf needs to allow each event to have its own sample_type >>> and not force a minimal compatibility. >> >> >> Why? The impact is small. The kernel API is completely unchanged. > > > I'd like to see libperf become a stable, usable library - usable by more than the perf binary and its builtin commands. I have already done this once for a daemon, and it was a PITA to get the specific use functional without memory leaks/growth in the libperf part. > > With respect to this specific patch it means appropriate flexibility in the data collected for events. ie., each event can have its own sample_type. For example if the tracepoint already contains task information TID is not needed - and IP may not be wanted either. The code processing the samples should not require all events to have some minimum data format - that just wastes buffer space. > I agree. This kernel needs to allow for any bit combination on sample_type and yet provide enough info to parse the buffer in the case of multi-event sampling. This is kernel bug. Tools should not have to handle this. Because it'd have to be repeated for each tool. Later this week, I'll post a patch that address the kernel limitation. -- 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/