From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933211AbaE3OEd (ORCPT ); Fri, 30 May 2014 10:04:33 -0400 Received: from service87.mimecast.com ([91.220.42.44]:50085 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751529AbaE3OEc convert rfc822-to-8bit (ORCPT ); Fri, 30 May 2014 10:04:32 -0400 Message-ID: <53888FF0.4020403@arm.com> Date: Fri, 30 May 2014 15:04:32 +0100 From: Dietmar Eggemann User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Vincent Guittot , "peterz@infradead.org" , "mingo@kernel.org" , "linux-kernel@vger.kernel.org" , "linux@arm.linux.org.uk" , "linux-arm-kernel@lists.infradead.org" CC: "preeti@linux.vnet.ibm.com" , Morten Rasmussen , "efault@gmx.de" , "nicolas.pitre@linaro.org" , "linaro-kernel@lists.linaro.org" , "daniel.lezcano@linaro.org" Subject: Re: [PATCH v2 04/11] sched: Allow all archs to set the power_orig References: <1400860385-14555-1-git-send-email-vincent.guittot@linaro.org> <1400860385-14555-5-git-send-email-vincent.guittot@linaro.org> In-Reply-To: <1400860385-14555-5-git-send-email-vincent.guittot@linaro.org> X-OriginalArrivalTime: 30 May 2014 14:04:27.0648 (UTC) FILETIME=[11C50800:01CF7C10] X-MC-Unique: 114053015043010801 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23/05/14 16:52, Vincent Guittot wrote: > power_orig is only changed for system with a SMT sched_domain level in order to > reflect the lower capacity of CPUs. Heterogenous system also have to reflect an > original capacity that is different from the default value. > > Create a more generic function arch_scale_cpu_power that can be also used by > non SMT platform to set power_orig. > > The weak behavior of arch_scale_cpu_power is the previous SMT one in order to > keep backward compatibility in the use of power_orig. > > Signed-off-by: Vincent Guittot As you know, besides uarch scaled cpu power for HMP, freq scaled cpu power is important for energy-aware scheduling to achieve freq scale invariance for task load. I know that your patch-set is not about introducing freq scaled cpu power, but we were discussing how this can be achieved w/ your patch-set in place, so maybe you can share your opinion regarding the easiest way to achieve freq scale invariance with us? (1) We assume that the current way (update_cpu_power() calls arch_scale_freq_power() to get the avg power(freq) over the time period since the last call to arch_scale_freq_power()) is suitable for us. Do you have another opinion here? (2) Is the current layout of update_cpu_power() adequate for this, where we scale power_orig related to freq and then related to rt/(irq): power_orig = scale_cpu(SCHED_POWER_SCALE) power = scale_rt(scale_freq(power_orig)) or do we need an extra power_freq data member on the rq and do: power_orig = scale_cpu(SCHED_POWER_SCALE) power_freq = scale_freq(power_orig)) power = scale_rt(power_orig)) In other words, do we consider rt/(irq) pressure when calculating freq scale invariant task load or not? Thanks, -- Dietmar [...]