From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's Date: Mon, 28 Oct 2013 17:24:38 +0100 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 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 To: Neil Horman Return-path: Content-Disposition: inline In-Reply-To: <20131028160131.GA31048@hmsreliant.think-freely.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org * 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