From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Doug Smythies" Subject: RE: [PATCH v1 2/2] intel_pstate: Change the setpoint for the cores Date: Sat, 21 Nov 2015 08:22:24 -0800 Message-ID: <001801d12478$ceb35630$6c1a0290$@net> References: <1446542840-14982-1-git-send-email-philippe.longepe@linux.intel.com> <1446542840-14982-2-git-send-email-philippe.longepe@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from cmta11.telus.net ([209.171.16.84]:37152 "EHLO cmta11.telus.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761228AbbKUQW0 (ORCPT ); Sat, 21 Nov 2015 11:22:26 -0500 In-Reply-To: <1446542840-14982-2-git-send-email-philippe.longepe@linux.intel.com> Content-Language: en-ca Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: 'Philippe Longepe' , 'Stephane Gasparini' Cc: srinivas.pandruvada@linux.intel.com, linux-pm@vger.kernel.org On 2015.11.03 01:27 Philippe Longepe wrote: > Change the setpoint to 60 accordingly to the new core busy scaled formula. > The new formaula is based on the number of cycles per seconds > (average frequency) divided by the requested frequency. So, we need to > chose a setpoint more aggressive to improve performance. Myself, and so as to improve response to some games and such that use many threads and such but often a lower overall CPU load, I think the setpoint should be set a little lower. There is a tradeoff in reducing the setpoint further as it increases the noise and tendency to oscillate in the response curve. Ultimately, it may be desirable to introduce a little slope in the load / CPU frequency response curve. I have a bunch of graphs comparing response curves. [1] > > Measured with this parameter, we noticed an improvement in Browsermark > for power and perf compared to the old formula: I would like to try this test on my system. What is the exact test? Do I understand correctly, that I need a browser to do the test? (my test system is a server, and it doesn't have a browser.) > > Score without the patch: 3517 > Power without the patch: 6856 mW > > Score with the patch: 3719 > Power with the patch: 6265 mW There are some other Phoronix tests that we (the original maintainer and the a couple of others working with him used to use. See [1]. Please be aware that the last time I tried to bring back load based calculations, Kristen tested the proposed solution on some intel "specpower test bed and experienced a regression on haswell based server platforms vs. Dirks algorithm." I don't have any details. Your response curve, and in particular your step function response time, is different, so it might worth re-testing. References: [1] double u double u double u dot smythies dot com/~doug/linux/intel_pstate/philippe_longepe/index.html