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 283E4C2B9F7 for ; Wed, 26 May 2021 11:52:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0262661132 for ; Wed, 26 May 2021 11:52:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234559AbhEZLyY (ORCPT ); Wed, 26 May 2021 07:54:24 -0400 Received: from foss.arm.com ([217.140.110.172]:43426 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234573AbhEZLwV (ORCPT ); Wed, 26 May 2021 07:52:21 -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 5D54C1516; Wed, 26 May 2021 04:50:49 -0700 (PDT) Received: from [10.57.31.7] (unknown [10.57.31.7]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 675A13F73B; Wed, 26 May 2021 04:50:47 -0700 (PDT) Subject: Re: [PATCH v2 0/3] EM / PM: Inefficient OPPs From: Lukasz Luba To: Viresh Kumar Cc: Vincent Donnefort , peterz@infradead.org, rjw@rjwysocki.net, vincent.guittot@linaro.org, qperret@google.com, linux-kernel@vger.kernel.org, ionela.voinescu@arm.com, dietmar.eggemann@arm.com References: <1621616064-340235-1-git-send-email-vincent.donnefort@arm.com> <20210526034751.5fl4kekq73gqy2wq@vireshk-i7> <20210526090141.GA408481@e120877-lin.cambridge.arm.com> <20210526093807.sih5y4lgltsz3r74@vireshk-i7> <17d88121-4809-dc31-1b57-2134ec868c8b@arm.com> Message-ID: <4a3db514-bec5-394f-ec3f-15c23b44b8f6@arm.com> Date: Wed, 26 May 2021 12:50:45 +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 5/26/21 11:39 AM, Lukasz Luba wrote: > [snip] To summarize: - we don't want to disable some OPPs - we want to give a 'hint' from energy perspective - we rely on SchedUtil 2nd stage which clamps this freq hint value to allowed OPPs which might set actually not the one what we see as 'efficient' -- we don't harm some existing platform which might needs these 'inefficient' OPPs in some use cases - we pay some extra cost in this SchedUtil freq switch path, which shouldn't harm too much. -- we pay this cost only for arm/arm64 platforms which use EM -- this cost is balanced by the benefit that we see in benchmarks and measured energy -- the LUT might limit the impact I hope this would help to better understand the scope and impact of this patch set. Regards, Lukasz