Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754173Ab3J2LUo (ORCPT ); Tue, 29 Oct 2013 07:20:44 -0400 Received: from charlotte.tuxdriver.com ([70.61.120.58]:36224 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751237Ab3J2LUn (ORCPT ); Tue, 29 Oct 2013 07:20:43 -0400 Date: Tue, 29 Oct 2013 07:20:22 -0400 From: Neil Horman To: Ingo Molnar 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: <20131029112022.GA24477@neilslaptop.think-freely.org> References: <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> <20131028162438.GB14350@gmail.com> <20131028174630.GB31048@hmsreliant.think-freely.org> <20131028182913.GD31048@hmsreliant.think-freely.org> <20131029082542.GA24625@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131029082542.GA24625@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Spam-Score: -2.9 (--) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1693 Lines: 48 On Tue, Oct 29, 2013 at 09:25:42AM +0100, Ingo Molnar wrote: > > * Neil Horman wrote: > > > Heres my data for running the same test with taskset restricting > > execution to only cpu0. I'm not quite sure whats going on here, > > but doing so resulted in a 10x slowdown of the runtime of each > > iteration which I can't explain. As before however, both the > > parallel alu run and the prefetch run resulted in speedups, but > > the two together were not in any way addative. I'm going to keep > > playing with the prefetch stride, unless you have an alternate > > theory. > > Could you please cite the exact command-line you used for running > the test? > > Thanks, > > Ingo > Sure it was this: for i in `seq 0 1 3` do echo $i > /sys/module/csum_test/parameters/module_test_mode taskset -c 0 perf stat --repeat 20 -C 0 -ddd perf bench sched messaging -- /root/test.sh done >> counters.txt 2>&1 where test.sh is: #!/bin/sh echo 1 > /sys/module/csum_test/parameters/test_fire As before, module_test_mode selects a case in a switch statement I added in do_csum to test one of the 4 csum variants we've been discusing (base, prefetch, parallel ALU or both), and test_fire is a callback trigger I use in the test module to run 100000 iterations of a checksum operation. As you requested, I ran the above on cpu 0 (-C 0 on perf and -c 0 on taskset), and I removed all irq affinity to cpu 0. Regards Neil -- 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/