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 71042C001B0 for ; Mon, 3 Jul 2023 16:09:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230515AbjGCQJf (ORCPT ); Mon, 3 Jul 2023 12:09:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229885AbjGCQJd (ORCPT ); Mon, 3 Jul 2023 12:09:33 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 53A51138; Mon, 3 Jul 2023 09:09:32 -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 2F6172F4; Mon, 3 Jul 2023 09:10:14 -0700 (PDT) Received: from [10.57.27.93] (unknown [10.57.27.93]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E6DFF3F663; Mon, 3 Jul 2023 09:09:28 -0700 (PDT) Message-ID: Date: Mon, 3 Jul 2023 17:09:46 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v2 14/17] Documentation: EM: Add a new section about the design Content-Language: en-US To: Dietmar Eggemann Cc: rui.zhang@intel.com, amit.kucheria@verdurent.com, amit.kachhap@gmail.com, daniel.lezcano@linaro.org, viresh.kumar@linaro.org, len.brown@intel.com, pavel@ucw.cz, Pierre.Gondois@arm.com, ionela.voinescu@arm.com, rostedt@goodmis.org, mhiramat@kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rafael@kernel.org References: <20230512095743.3393563-1-lukasz.luba@arm.com> <20230512095743.3393563-15-lukasz.luba@arm.com> <0968c915-0344-b08f-7117-5b1ff6b126fd@arm.com> From: Lukasz Luba In-Reply-To: <0968c915-0344-b08f-7117-5b1ff6b126fd@arm.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 On 5/30/23 11:33, Dietmar Eggemann wrote: > On 12/05/2023 11:57, Lukasz Luba wrote: >> Add a new section 'Design' which covers the information about Energy >> Model. It contains the design decisions, describes models and how they >> reflect the reality. Add description of the basic const. EM. Change the >> other section IDs. > > I would vote for coalescing the 4 doc patches into 1. OK, I can make that. I will be a big one patch, though. > >> >> Signed-off-by: Lukasz Luba >> --- >> Documentation/power/energy-model.rst | 36 +++++++++++++++++++++------- >> 1 file changed, 27 insertions(+), 9 deletions(-) >> >> diff --git a/Documentation/power/energy-model.rst b/Documentation/power/energy-model.rst >> index ef341be2882b..e97c7f18d8bd 100644 >> --- a/Documentation/power/energy-model.rst >> +++ b/Documentation/power/energy-model.rst >> @@ -72,16 +72,34 @@ required to have the same micro-architecture. CPUs in different performance >> domains can have different micro-architectures. >> >> >> -2. Core APIs >> +2. Design >> +----------------- >> + >> +2.1 Basic EM >> +^^^^^^^^^^^^ > > Can we make sure that people get the relation between 'basic' and > 'default' easier? > > It should be obvious that `pd->default_table->state` refers to this > `basic (const.) EM. Using the same identifier always helps in this > situation. OK, how about adding this: "The basic EM is built around const. power information for each performance state, which is accessible in: 'dev->em_pd->default_table->state'. This model can be derived based..." > >> + >> +The basic EM is built around const. power information for each performance >> +state. This model can be derived based on power measurements of the device >> +e.g. CPU while running some benchmark. The benchmark might be integer heavy >> +or floating point computation with a data set fitting into the CPU cache or >> +registers. Bare in mind that this model might not be covering all possible >> +workloads running on CPUs. Thus, please run a few different benchmarks and >> +verify with some real workloads your power model values. The power variation >> +due to the workload instruction mix and data set is not modeled. >> +Also static power which can change during runtime due to variation of SOC >> +temperature is not modeled in EM. >> + >> +