From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: Re: [Results] [RFC PATCH v4 00/40] mm: Memory Power Management Date: Tue, 12 Nov 2013 13:32:35 +0530 Message-ID: <5281E09B.3060303@linux.vnet.ibm.com> References: <20130925231250.26184.31438.stgit@srivatsabhat.in.ibm.com> <52437128.7030402@linux.vnet.ibm.com> <20130925164057.6bbaf23bdc5057c42b2ab010@linux-foundation.org> <52442F6F.5020703@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from e28smtp08.in.ibm.com ([122.248.162.8]:49327 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754753Ab3KLIHL (ORCPT ); Tue, 12 Nov 2013 03:07:11 -0500 Received: from /spool/local by e28smtp08.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 12 Nov 2013 13:37:09 +0530 In-Reply-To: <52442F6F.5020703@linux.vnet.ibm.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Andrew Morton Cc: mgorman@suse.de, dave@sr71.net, hannes@cmpxchg.org, tony.luck@intel.com, matthew.garrett@nebula.com, riel@redhat.com, arjan@linux.intel.com, srinivas.pandruvada@linux.intel.com, willy@linux.intel.com, kamezawa.hiroyu@jp.fujitsu.com, lenb@kernel.org, rjw@sisk.pl, gargankita@gmail.com, paulmck@linux.vnet.ibm.com, svaidy@linux.vnet.ibm.com, andi@firstfloor.org, isimatu.yasuaki@jp.fujitsu.com, santosh.shilimkar@ti.com, kosaki.motohiro@gmail.com, linux-pm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, maxime.coquelin@stericsson.com, loic.pallardy@stericsson.com, amit.kachhap@linaro.org, thomas.abraham@linaro.org, markgross@thegnar.org On 09/26/2013 06:28 PM, Srivatsa S. Bhat wrote: > On 09/26/2013 05:10 AM, Andrew Morton wrote: >> On Thu, 26 Sep 2013 04:56:32 +0530 "Srivatsa S. Bhat" wrote: >> >>> Experimental Results: >>> ==================== >>> >>> Test setup: >>> ---------- >>> >>> x86 Sandybridge dual-socket quad core HT-enabled machine, with 128GB RAM. >>> Memory Region size = 512MB. >> >> Yes, but how much power was saved ;) >> > > I don't have those numbers yet, but I'll be able to get them going forward. > Hi, I performed experiments on an IBM POWER 7 machine and got actual power-savings numbers (upto 2.6% of total system power) from this patchset. I presented them at the Kernel Summit but forgot to post them on LKML. So here they are: Hardware-setup: -------------- IBM POWER 7 machine: 4 socket (NUMA), 32 cores, 128GB RAM - 4 NUMA nodes with 32 GB RAM each - Booted with numa=fake=1 and treated them as 4 memory regions Software setup: -------------- Workload: Run modified ebizzy for half an hour, which allocates and frees large quantities of memory frequently. The modified ebizzy touches every allocated page a number of times (4 times) before freeing it up. This ensures that allocating a page in the "wrong" memory region makes it very costly in terms of power-savings, since every allocated page is accessed before getting freed (and accesses cause energy consumption). Thus, with this modified benchmark, sub-optimal MM decisions (in terms of memory power-savings) get magnified and hence become noticeable. Power-savings compared to mainline (3.12-rc4): --------------------------------------------- With this patchset applied, the average power of the system reduced by 2.6% compared to the mainline kernel during the benchmark run. The total system power is an excellent metric for such evaluations, since it brings out the overall power-efficiency of the patchset. (IOW, if the patchset shoots up the CPU or disk power-consumption while causing memory power savings, then the total system power will not show much difference). So these numbers indicate that the patchset performs quite well in reducing the power-consumption of the system as a whole. This is not the most ideal hardware configuration to test on, since I had only 4 memory regions to play with, but this gives a good initial indication of the kind of power savings that can be achieved with this patchset. I am expecting the same patchset to give us power-savings of upto 5% of the total system power on a newer prototype hardware that I have (since it has more memory regions and lower base power consumption). Regards, Srivatsa S. Bhat