Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760336AbaGYOOT (ORCPT ); Fri, 25 Jul 2014 10:14:19 -0400 Received: from mail.kernel.org ([198.145.19.201]:58794 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751877AbaGYOOS (ORCPT ); Fri, 25 Jul 2014 10:14:18 -0400 Date: Fri, 25 Jul 2014 11:14:13 -0300 From: Arnaldo Carvalho de Melo To: Jiri Olsa Cc: Jiri Olsa , linux-kernel@vger.kernel.org, Adrian Hunter , Corey Ashford , David Ahern , Frederic Weisbecker , Ingo Molnar , Jean Pihet , Namhyung Kim , Paul Mackerras , Peter Zijlstra Subject: Re: [PATCH 17/19] perf tools: Always force PERF_RECORD_FINISHED_ROUND event Message-ID: <20140725141413.GK7831@kernel.org> References: <1405893363-21967-1-git-send-email-jolsa@kernel.org> <1405893363-21967-18-git-send-email-jolsa@kernel.org> <20140724213451.GH7831@kernel.org> <20140725113426.GC1214@krava.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140725113426.GC1214@krava.brq.redhat.com> X-Url: http://acmel.wordpress.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 Em Fri, Jul 25, 2014 at 01:34:26PM +0200, Jiri Olsa escreveu: > On Thu, Jul 24, 2014 at 06:34:51PM -0300, Arnaldo Carvalho de Melo wrote: > > I think both changes are OK, but should be split in different patches, > right, I'll split it Thanks! > > [root@zoo /]# perf stat -r 5 perf report --no-ordered-samples > /dev/null > > 101,171,572,553 instructions # 1.10 insns per cycle > > 30.249514999 seconds time elapsed ( +- 0.48% ) > > [root@zoo /]# perf stat -r 5 perf report --ordered-samples > /dev/null > > 105,982,144,263 instructions # 1.04 insns per cycle > > 32.636483981 seconds time elapsed ( +- 0.41% ) > so those 2 extra seconds is the ordering time, right? sounds ok Yeah, but I think its worth investigating if using it is a strict requirement in all cases, i.e. is it possible to receive out of order events when sampling on a single CPU? Or a single CPU socket with a coherent time source? etc. Providing a way to disable this ordering to be used in corner cases where it is not a strict requirement and the volume of samples is so high that reducing processing time like shown above seems to be a sensible thing to do. We're in the business of optimizing stuff, huh? :-) - Arnaldo -- 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/