From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48933C43334 for ; Thu, 9 Jun 2022 12:54:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244683AbiFIMx4 (ORCPT ); Thu, 9 Jun 2022 08:53:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343641AbiFIMx1 (ORCPT ); Thu, 9 Jun 2022 08:53:27 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 884867DE33 for ; Thu, 9 Jun 2022 05:53:26 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1BB7412FC; Thu, 9 Jun 2022 05:53:26 -0700 (PDT) Received: from [10.57.39.144] (unknown [10.57.39.144]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 070143F73B; Thu, 9 Jun 2022 05:53:23 -0700 (PDT) Message-ID: <6099583c-c986-e1f3-1eee-33b504286757@arm.com> Date: Thu, 9 Jun 2022 13:53:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v10 0/7] feec() energy margin removal Content-Language: en-US To: Vincent Donnefort Cc: linux-kernel@vger.kernel.org, dietmar.eggemann@arm.com, morten.rasmussen@arm.com, chris.redpath@arm.com, qperret@google.com, tao.zhou@linux.dev, kernel-team@android.com, peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org References: <20220607123254.565579-1-vdonnefort@google.com> From: Lukasz Luba In-Reply-To: <20220607123254.565579-1-vdonnefort@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Vincent, On 6/7/22 13:32, Vincent Donnefort wrote: > Hi, > > Here's a new version of the patch-set to get rid of the energy margin in > feec(). Many thanks to all for the insightful comments I got. > > find_energy_efficient() (feec()) will migrate a task to save energy only if > it saves at least 6% of the total energy consumed by the system. This > conservative approach is a problem on a system where a lot of small tasks > create a huge load on the overall: very few of them will be allowed to > migrate to a smaller CPU, wasting a lot of energy. Instead of trying to > determine yet another margin, let's try to remove it. > > The first elements of this patch-set are various fixes and improvement that > stabilizes task_util and ensures energy comparison fairness across all CPUs > of the topology. Only once those fixed, we can completely remove the margin > and let feec() aggressively place task and save energy. > I've run this patch set on pixel6 (android-mainline) and gathered energy values from the meter during the PCmark 3.0. It looks good, with these patches we have ~10% lower energy usage and only ~3% lower score. There are no other issues, everything works fine. Feel free to add: Tested-by: Lukasz Luba to the whole patch set. Regards, Lukasz