Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760124Ab3EXIvf (ORCPT ); Fri, 24 May 2013 04:51:35 -0400 Received: from mail-oa0-f41.google.com ([209.85.219.41]:49509 "EHLO mail-oa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759956Ab3EXIvb (ORCPT ); Fri, 24 May 2013 04:51:31 -0400 MIME-Version: 1.0 In-Reply-To: <20130524103007.7bb206ee@amdc308.digital.local> References: <1367590072-10496-1-git-send-email-jonghwa3.lee@samsung.com> <20130522122700.104ca5cd@amdc308.digital.local> <20130522164453.29cd3a7d@amdc308.digital.local> <20130524075640.0a5b80ff@amdc308.digital.local> <20130524103007.7bb206ee@amdc308.digital.local> Date: Fri, 24 May 2013 14:21:30 +0530 Message-ID: Subject: Re: [RFC v2 0/3][TESTS] LAB: Support for Legacy Application Booster governor - tests results From: Viresh Kumar To: Lukasz Majewski Cc: Jonghwa Lee , "Rafael J. Wysocky" , linux-kernel@vger.kernel.org, cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, Vicent Guittot , Daniel Lezcano , MyungJoo Ham , Lukasz Majewski Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1975 Lines: 50 On 24 May 2013 14:00, Lukasz Majewski wrote: > The overclock frequency (1.5 GHz) is possible to set as an ordinary, > available frequency (policy->max) for ondemand. > > Unfortunately with our load patterns, this frequency rapidly increases > internal chip temperature (chip goes out of available power/thermal > dissipation range), and consumes extra power when not needed. > > The core idea with overclock is to increase ("boost") the frequency > when conditions allow to do it (for example load is affined to a single > core, other are idle). Then we will not exceed power/thermal budget, but > increase performance (and even save power). > > > Overclocking is efficiently utilized by LAB, which relies on a number of > idle cpus. Thus, we can easily asses if we can enable it. > > I also foresee potential use of overclocking, when scheduler will take a > major role of power saver for mobile (ARM) linux. Since it will try to > pack as much tasks as possible to a single core - it will need a > framework/API to "boost" their execution. Okay.. so its exactly what I thought the reason would be. What I would have done if I was in your place is: Add following sysfs tunables to ondemand governor: - overdrive_freq: We will go over this frequency only when number of busy cores is <= overdrive_cores.. For your case it will be 1.4 GHz - overdrive_cores: We will enable overdrive frequencies only if no. of busy cores is <= overdrive_cores. Zero by default (So, that this feature is disabled by default) and 1 for your case. And your driver will include all the available frequencies in the freq table. I hope this will be the most generic solution to your problem.. What do you say? -- viresh -- 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/