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 2C9D2C2D0A3 for ; Thu, 12 Nov 2020 16:01:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DDC1022227 for ; Thu, 12 Nov 2020 16:01:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728753AbgKLQBu (ORCPT ); Thu, 12 Nov 2020 11:01:50 -0500 Received: from foss.arm.com ([217.140.110.172]:53392 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728430AbgKLQBt (ORCPT ); Thu, 12 Nov 2020 11:01:49 -0500 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 5CDBF142F; Thu, 12 Nov 2020 08:01:49 -0800 (PST) Received: from [192.168.178.2] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C1F843F73C; Thu, 12 Nov 2020 08:01:47 -0800 (PST) Subject: Re: [PATCH v5 1/1] sched/uclamp: add SCHED_FLAG_UTIL_CLAMP_RESET flag to reset uclamp To: Qais Yousef Cc: Peter Zijlstra , Yun Hsiang , linux-kernel@vger.kernel.org, patrick.bellasi@matbug.net, kernel test robot References: <20201103023756.1012088-1-hsiang023167@gmail.com> <20201110122108.GG2594@hirez.programming.kicks-ass.net> <20201112144131.7gqglj435bs6otwm@e107158-lin.cambridge.arm.com> From: Dietmar Eggemann Message-ID: Date: Thu, 12 Nov 2020 17:01:46 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201112144131.7gqglj435bs6otwm@e107158-lin.cambridge.arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/11/2020 15:41, Qais Yousef wrote: > On 11/11/20 18:41, Dietmar Eggemann wrote: >> On 10/11/2020 13:21, Peter Zijlstra wrote: >>> On Tue, Nov 03, 2020 at 10:37:56AM +0800, Yun Hsiang wrote: [...] > I assume we agree then that we don't want to explicitly document this quirky > feature and keep it for advanced users? > > I am wary of the UAPI change that is both explicit and implicit. It explicitly > requests a reset, but implicitly requests a cgroup behavior change. > > With this magic value at least we can more easily return an error if we decided > to deprecate it, which has been my main ask so far. I don't want us to end up > not being able to easily modify this code in the future. Another advantage for this 'magic value' approach. > I don't have strong opinion too though. > > If you or Yun would still like to send the patch to protect > SCHED_FLAG_UTIL_CLAMP and SCHED_FLAG_ALL with __kernel__ that'd be great. Ah yes! Can add an extra patch for this when sending out the next version. [...]