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=-8.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 7B8EBC2D0A3 for ; Thu, 12 Nov 2020 13:05:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 300BB21D7F for ; Thu, 12 Nov 2020 13:05:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727942AbgKLNF6 (ORCPT ); Thu, 12 Nov 2020 08:05:58 -0500 Received: from foss.arm.com ([217.140.110.172]:49828 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727739AbgKLNF5 (ORCPT ); Thu, 12 Nov 2020 08:05:57 -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 2E43D101E; Thu, 12 Nov 2020 05:05:57 -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 B70873F718; Thu, 12 Nov 2020 05:05:55 -0800 (PST) Subject: Re: [PATCH v5 1/1] sched/uclamp: add SCHED_FLAG_UTIL_CLAMP_RESET flag to reset uclamp To: Peter Zijlstra Cc: Yun Hsiang , linux-kernel@vger.kernel.org, qais.yousef@arm.com, patrick.bellasi@matbug.net, kernel test robot References: <20201103023756.1012088-1-hsiang023167@gmail.com> <20201110122108.GG2594@hirez.programming.kicks-ass.net> <20201111180441.GJ2628@hirez.programming.kicks-ass.net> From: Dietmar Eggemann Message-ID: <82f26263-a5cd-bd5c-52bd-37b98663a2e5@arm.com> Date: Thu, 12 Nov 2020 14:05:46 +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: <20201111180441.GJ2628@hirez.programming.kicks-ass.net> 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 11/11/2020 19:04, Peter Zijlstra wrote: > On Wed, Nov 11, 2020 at 06:41:07PM +0100, Dietmar Eggemann wrote: >> diff --git a/include/uapi/linux/sched/types.h b/include/uapi/linux/sched/types.h >> index c852153ddb0d..b9165f17dddc 100644 >> --- a/include/uapi/linux/sched/types.h >> +++ b/include/uapi/linux/sched/types.h >> @@ -115,8 +115,8 @@ struct sched_attr { >> __u64 sched_period; >> >> /* Utilization hints */ >> - __u32 sched_util_min; >> - __u32 sched_util_max; >> + __s32 sched_util_min; >> + __s32 sched_util_max; > > So that's UAPI, not sure we can change the type here. Yes, will remove this chunk. Not needed. I probably should add some documentation there: diff --git a/include/uapi/linux/sched/types.h b/include/uapi/linux/sched/types.h index c852153ddb0d..f2c4589d4dbf 100644 --- a/include/uapi/linux/sched/types.h +++ b/include/uapi/linux/sched/types.h @@ -96,6 +96,8 @@ struct sched_param { * on a CPU with a capacity big enough to fit the specified value. * A task with a max utilization value smaller than 1024 is more likely * scheduled on a CPU with no more capacity than the specified value. + * + * A task utilization boundary can be reset by setting the attribute to -1. */ struct sched_attr { __u32 size; [...] >> + if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) { >> + util_max = attr->sched_util_max; >> + >> + if (util_max < -1 || util_max > SCHED_CAPACITY_SCALE) >> + return -EINVAL; >> + } > > Luckily we can write that range as a single branch like: > > if (util_{min,max} + 1 > SCHED_CAPACITY_SCALE+1) > > which assumes u32 :-) Cool, will change it. >> + >> + if (util_min != -1 && util_max != -1 && util_min > util_max) >> return -EINVAL; > > I think that will compile as is, otherwise write it like ~0u, which is > the same bit pattern. Yes, it compiles for me (arm64, gcc 9.2 and arm, gcc 8.3). Started a 0-Day build job to make sure. Will do some more testing before sending out the updated version.