Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757118AbZABHX1 (ORCPT ); Fri, 2 Jan 2009 02:23:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751624AbZABHXS (ORCPT ); Fri, 2 Jan 2009 02:23:18 -0500 Received: from e28smtp06.in.ibm.com ([59.145.155.6]:40818 "EHLO e28smtp06.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751426AbZABHXR (ORCPT ); Fri, 2 Jan 2009 02:23:17 -0500 Date: Fri, 2 Jan 2009 12:56:00 +0530 From: Vaidyanathan Srinivasan To: Ingo Molnar Cc: Balbir Singh , linux-kernel@vger.kernel.org, Peter Zijlstra , Andrew Morton Subject: Re: [PATCH v7 0/8] Tunable sched_mc_power_savings=n Message-ID: <20090102072600.GA13412@dirshya.in.ibm.com> Reply-To: svaidy@linux.vnet.ibm.com References: <20081218175313.29812.4781.stgit@drishya.in.ibm.com> <28c262360812291543ia322a13g6af854a685ce7632@mail.gmail.com> <20081230024819.GA23301@balbir.in.ibm.com> <20081230062139.GA30038@elte.hu> <20081230180722.GA29060@dirshya.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20081230180722.GA29060@dirshya.in.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4234 Lines: 118 * Vaidyanathan Srinivasan [2008-12-30 23:37:22]: > * Ingo Molnar [2008-12-30 07:21:39]: > > > > > * Balbir Singh wrote: > > > > > > > KERNBENCH Runs: make -j4 on a x86 8 core, dual socket quad core cpu > > > > > package system > > > > > > > > > > SchedMC Run Time Package Idle Energy Power > > > > > 0 81.68 52.83% 54.71% 1.00x J 1.00y W > > > > > 1 80.70 36.62% 70.11% 0.95x J 0.96y W > > > > > 2 74.95 19.53% 85.92% 0.90x J 0.98y W > > > > > > Your result is very interesting. > > > > level 2 is more fast and efficient of power. > > > > > > > > What's major contributor to use less time in level 2? > > > > I think it's cache bounce is less time than old. > > > > Is right ? > > > > > > Yes, correct > > > > yes, i too noticed that runtime improved so dramatically: +7.5% on > > kernbench is a _very_ big deal. > > > > So i wanted to ask you to re-test whether this speedup is reproducible, > > and if yes, please check a few other workloads (for example sysbench on > > postgresql / mysqld) and send a patch that changes the > > sched_mc_power_savings default to POWERSAVINGS_BALANCE_WAKEUP (2). > > The speedup for kernbench is reproducible. I will post a more > detailed test report on kernbench soon. The power-performance benefit > is for an under-utilised system (nr_cpus/2) run of kernbench which is > very ideal to demonstrate the power savings feature. I will also try > sysbench and update results little later. As Balbir mentioned, I am > on vacation and traveling. I will post more benchmark results as soon > as possible. Hi Ingo, I ran my kernbench test setup over multiple iterations with several thread counts. The performance will almost max out at 8-10 threads of kernbench since the system has total of 8 logical CPUs. The power saving benefits is expected to be maximum around 30-50% system utilisation (3-5 threads). I have posted the normalised results in various tables below. Apparently the sched_mc=2 settings is helping at 8 threads case also due to better cache line sharing. I will work with Balbir to see if we can prove this assertion using performance counters. I will start looking at sysbench and try to get benchmark results and power/energy data in similar configurations. --Vaidy All these tests were done on sched-tip at commit: fe235c6b2a4b9eb11909fe40249abcce67f7d45d uname -a is 2.6.28-rc8-tip-sv-05664-gfe235c6-dirty Kernbench was run on source 2.6.28 while the previous tests used 2.6.25 kernel which had far less stuff to compile in defconfig :) System configuration is x86 quad core dual socket system with 8 logical CPUs Each result is an average of 5 iterations. Kernbench threads = 2 SchedMC Run Time Package Idle(%) Energy(J) Power(W) 0 217.37 73.30 76.93 1.00 1.00 1 204.68 50.86 99.91 0.95 1.01 2 204.49 50.69 99.93 0.95 1.01 Kernbench threads = 4 SchedMC Run Time Package Idle(%) Energy(J) Power(W) 0 109.11 51.99 54.91 1.00 1.00 1 109.71 35.86 71.88 0.96 0.96 2 102.95 25.02 82.47 0.92 0.97 Kernbench threads = 6 SchedMC Run Time Package Idle(%) Energy(J) Power(W) 0 74.77 35.29 36.37 1.00 1.00 1 74.54 28.83 40.90 0.99 0.99 2 73.38 21.09 47.29 0.98 1.00 Kernbench threads = 8 SchedMC Run Time Package Idle(%) Energy(J) Power(W) 0 63.18 26.23 28.67 1.00 1.00 1 56.89 19.85 22.38 0.93 1.02 2 55.27 17.65 19.84 0.91 1.03 Relative measures for sched_mc=1 compared to baseline sched_mc=0 Threads=> 2 4 6 8 10 12 KernbenchTime 0.94 1.01 1.00 0.90 0.93 0.95 Energy 0.95 0.96 0.99 0.93 0.95 0.97 Power 1.01 0.96 0.99 1.02 1.02 1.01 Relative measures for sched_mc=2 compared to baseline sched_mc=0 Threads=> 2 4 6 8 10 12 KernbenchTime 0.94 0.94 0.98 0.87 0.92 0.94 Energy 0.95 0.92 0.98 0.91 0.94 0.96 Power 1.01 0.97 1.00 1.03 1.02 1.02 -- 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/