From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756650Ab2I0Kot (ORCPT ); Thu, 27 Sep 2012 06:44:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10100 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756215Ab2I0Kor (ORCPT ); Thu, 27 Sep 2012 06:44:47 -0400 Message-ID: <50642E0C.6030105@redhat.com> Date: Thu, 27 Sep 2012 12:44:28 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120828 Thunderbird/15.0 MIME-Version: 1.0 To: Andrew Jones CC: Raghavendra K T , dlaor@redhat.com, Chegu Vinod , Peter Zijlstra , "H. Peter Anvin" , Marcelo Tosatti , Ingo Molnar , Rik van Riel , Srikar , "Nikunj A. Dadhania" , KVM , Jiannan Ouyang , "Andrew M. Theurer" , LKML , Srivatsa Vaddagiri , Gleb Natapov Subject: Re: [PATCH RFC 0/2] kvm: Improving undercommit,overcommit scenarios in PLE handler References: <20120921115942.27611.67488.sendpatchset@codeblue> <505C691D.4080801@hp.com> <505CA5BA.4020801@linux.vnet.ibm.com> <50601CE7.60801@redhat.com> <50604BF0.1070607@linux.vnet.ibm.com> <5061C70E.2090308@redhat.com> <50642139.80309@linux.vnet.ibm.com> <20120927102832.GA4106@turtle.usersys.redhat.com> In-Reply-To: <20120927102832.GA4106@turtle.usersys.redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/27/2012 12:28 PM, Andrew Jones wrote: >> No, I am not there yet. >> >> So In summary, we are suffering with inconsistent benchmark result, >> while measuring the benefit of our improvement in PLE/pvlock etc.. > > Are you measuring the combined throughput of all running guests, or > just looking at the results of the benchmarks in a single test guest? > > I've done some benchmarking as well and my stddevs look pretty good for > kcbench, ebizzy, dbench, and sysbench-memory. I do 5 runs for each > overcommit level (1.0 - 3.0, stepped by .25 or .5), and 2 runs of that > full sequence of tests (one with the overcommit levels in scrambled > order). The relative stddevs for each of the sets of 5 runs look pretty > good, and the data for the 2 runs match nicely as well. > > To try and get consistent results I do the following > - interleave the memory of all guests across all numa nodes on the > machine > - echo 0 > /proc/sys/kernel/randomize_va_space on both host and test > guest > - echo 3 > /proc/sys/vm/drop_caches on both host and test guest before > each run > - use a ramdisk for the benchmark output files on all running guests > - no periodically running services installed on the test guest > - HT is turned off as you do, although I'd like to try running again > with it turned back on > > Although, I still need to run again measuring the combined throughput > of all running vms (including the ones launched just to generate busy > vcpus). Maybe my results won't be as consistent then... > Another way to test is to execute perf stat -e 'kvm_exit exit_reason==40' sleep 10 to see how many PAUSEs were intercepted in a given time (except I just invented the filter syntax). The fewer we get, the more useful work the system does. This ignores kvm_vcpu_on_spin overhead though, so it's just a rough measure. -- error compiling committee.c: too many arguments to function