Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756877Ab3J1QYo (ORCPT ); Mon, 28 Oct 2013 12:24:44 -0400 Received: from mail-ee0-f54.google.com ([74.125.83.54]:59340 "EHLO mail-ee0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756441Ab3J1QYm (ORCPT ); Mon, 28 Oct 2013 12:24:42 -0400 Date: Mon, 28 Oct 2013 17:24:38 +0100 From: Ingo Molnar To: Neil Horman Cc: Eric Dumazet , linux-kernel@vger.kernel.org, sebastien.dugue@bull.net, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's Message-ID: <20131028162438.GB14350@gmail.com> References: <1381510298-20572-1-git-send-email-nhorman@tuxdriver.com> <20131012172124.GA18241@gmail.com> <20131014202854.GH26880@hmsreliant.think-freely.org> <1381785560.2045.11.camel@edumazet-glaptop.roam.corp.google.com> <1381789127.2045.22.camel@edumazet-glaptop.roam.corp.google.com> <20131017003421.GA31470@hmsreliant.think-freely.org> <20131017084121.GC22705@gmail.com> <20131028160131.GA31048@hmsreliant.think-freely.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131028160131.GA31048@hmsreliant.think-freely.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1188 Lines: 33 * Neil Horman wrote: > Looking at the specific cpu counters we get this: > > Base: > Total time: 0.179 [sec] > > Performance counter stats for 'perf bench sched messaging -- bash -c echo 1 > /sys/module/csum_test/parameters/test_fire' (20 runs): > > 1571.304618 task-clock # 5.213 CPUs utilized ( +- 0.45% ) > 14,423 context-switches # 0.009 M/sec ( +- 4.28% ) > 2,710 cpu-migrations # 0.002 M/sec ( +- 2.83% ) Hm, for these second round of measurements were you using 'perf stat -a -C ...'? The most accurate method of measurement for such single-threaded workloads is something like: taskset 0x1 perf stat -a -C 1 --repeat 20 ... this will bind your workload to CPU#0, and will do PMU measurements only there - without mixing in other CPUs or workloads. Thanks, Ingo -- 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/