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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFEF4C07E9C for ; Wed, 7 Jul 2021 10:29:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C63561CBD for ; Wed, 7 Jul 2021 10:29:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231367AbhGGKcS (ORCPT ); Wed, 7 Jul 2021 06:32:18 -0400 Received: from foss.arm.com ([217.140.110.172]:33952 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231137AbhGGKcR (ORCPT ); Wed, 7 Jul 2021 06:32:17 -0400 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 70EC1ED1; Wed, 7 Jul 2021 03:29:37 -0700 (PDT) Received: from [10.57.1.129] (unknown [10.57.1.129]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 64A7C3F694; Wed, 7 Jul 2021 03:29:34 -0700 (PDT) Subject: Re: [PATCH 1/3] sched/fair: Prepare variables for increased precision of EAS estimated energy To: Vincent Guittot Cc: linux-kernel , Chris Redpath , Dietmar Eggemann , Morten Rasmussen , Quentin Perret , "open list:THERMAL" , Peter Zijlstra , "Rafael J. Wysocki" , Viresh Kumar , Ingo Molnar , Juri Lelli , Steven Rostedt , segall@google.com, Mel Gorman , Daniel Bristot de Oliveira , CCj.Yeh@mediatek.com References: <20210625152603.25960-1-lukasz.luba@arm.com> <20210625152603.25960-2-lukasz.luba@arm.com> <2f43b211-da86-9d48-4e41-1c63359865bb@arm.com> <297df159-1681-f0a7-843d-f34d86e51d4c@arm.com> <27916860-33b1-f0a0-acff-4722a733c81b@arm.com> From: Lukasz Luba Message-ID: Date: Wed, 7 Jul 2021 11:29:32 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/7/21 11:11 AM, Vincent Guittot wrote: > On Wed, 7 Jul 2021 at 12:06, Lukasz Luba wrote: >> [snip] >> No. It's in 0.1uW scale, so 800Watts. Which is 16 CPUs * 64Watts > > Oh! you want 0.1uW precision .... This doesn't seem realistic at all. > I'm not even sure that the power model can even reach an accuracy of > 1mW > True, the EM is registering platform with 1mW precision, but 1uW precision makes more sense for internal EAS calculation. I don't force platforms to report 1uW power, I just want to operate on it internally. PowerCap and DTPM also operate internally on 1uW, so it's not that unrealistic that some kernel components want better resolution. But as Peter suggested, we might skip 32bit platforms for this issue. I have to discussed this internally.