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 D2637C433FE for ; Wed, 16 Nov 2022 11:53:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233659AbiKPLxt (ORCPT ); Wed, 16 Nov 2022 06:53:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233393AbiKPLxP (ORCPT ); Wed, 16 Nov 2022 06:53:15 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 1F1953F056; Wed, 16 Nov 2022 03:43:56 -0800 (PST) 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 876AC1477; Wed, 16 Nov 2022 03:44:02 -0800 (PST) Received: from [10.57.6.51] (unknown [10.57.6.51]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3DA443F663; Wed, 16 Nov 2022 03:43:52 -0800 (PST) Message-ID: <880b7332-562c-4934-4e92-493b112568c9@arm.com> Date: Wed, 16 Nov 2022 11:43:49 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH v1] Revert "cpufreq: schedutil: Move max CPU capacity to sugov_policy" Content-Language: en-US To: Saravana Kannan , Sam Wu Cc: "Rafael J. Wysocki" , Viresh Kumar , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , "Isaac J . Manjarres" , kernel-team@android.com, "Rafael J. Wysocki" , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20221110195732.1382314-1-wusamuel@google.com> From: Lukasz Luba In-Reply-To: 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 11/15/22 22:35, Saravana Kannan wrote: > On Thu, Nov 10, 2022 at 11:57 AM Sam Wu wrote: >> >> This reverts commit 6d5afdc97ea71958287364a1f1d07e59ef151b11. >> >> On a Pixel 6 device, it is observed that this commit increases >> latency by approximately 50ms, or 20%, in migrating a task >> that requires full CPU utilization from a LITTLE CPU to Fmax >> on a big CPU. Reverting this change restores the latency back >> to its original baseline value. >> >> Fixes: 6d5afdc97ea7 ("cpufreq: schedutil: Move max CPU capacity to sugov_policy") >> Cc: Lukasz Luba >> Cc: Saravana Kannan >> Cc: Isaac J. Manjarres >> Signed-off-by: Sam Wu > > Rafael, can we pick this up please? > > Lukasz, no objections to the idea itself, but it's causing regression > and we'd like to revert and then fix it. If you see this in mainline kernel, then I'm fine with reverting it. Then I will have to trace why this CPU capacity value can change over time in mainline kernel (while it shouldn't, because we register the cpufreq policy and the governor later, after we calculate the capacity in arch_topology.c). Maybe something has changed in mainline in the meantime in this CPU capacity setup code, which caused this side effect. I know that android-mainline has some different setup code for those custom vendor governors. I just want to eliminate this bit and be on the same page. Regards, Lukasz > > -Saravana >