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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 904BBC282DD for ; Tue, 7 Jan 2020 19:30:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6934B2077B for ; Tue, 7 Jan 2020 19:30:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728697AbgAGTal (ORCPT ); Tue, 7 Jan 2020 14:30:41 -0500 Received: from foss.arm.com ([217.140.110.172]:33626 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728307AbgAGTal (ORCPT ); Tue, 7 Jan 2020 14:30:41 -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 53C4330E; Tue, 7 Jan 2020 11:30:40 -0800 (PST) Received: from [192.168.0.7] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CDE953F534; Tue, 7 Jan 2020 11:30:37 -0800 (PST) Subject: Re: [PATCH] sched/rt: Add a new sysctl to control uclamp_util_min To: Quentin Perret , Qais Yousef Cc: Ingo Molnar , Peter Zijlstra , Steven Rostedt , Luis Chamberlain , Kees Cook , Iurii Zaikin , Juri Lelli , Vincent Guittot , Ben Segall , Mel Gorman , valentin.schneider@arm.com, Patrick Bellasi , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-team@android.com References: <20191220164838.31619-1-qais.yousef@arm.com> <20200107134234.GA158998@google.com> From: Dietmar Eggemann Message-ID: <8bb17e84-d43f-615f-d04d-c36bb6ede5e0@arm.com> Date: Tue, 7 Jan 2020 20:30:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200107134234.GA158998@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/01/2020 14:42, Quentin Perret wrote: > Hi Qais, > > On Friday 20 Dec 2019 at 16:48:38 (+0000), Qais Yousef wrote: [...] >> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c >> index e591d40fd645..19572dfc175b 100644 >> --- a/kernel/sched/rt.c >> +++ b/kernel/sched/rt.c >> @@ -2147,6 +2147,12 @@ static void pull_rt_task(struct rq *this_rq) >> */ >> static void task_woken_rt(struct rq *rq, struct task_struct *p) >> { >> + /* >> + * When sysctl_sched_rt_uclamp_util_min value is changed by the user, >> + * we apply any new value on the next wakeup, which is here. >> + */ >> + uclamp_rt_sync_default_util_min(p); > > The task has already been enqueued and sugov has been called by then I > think, so this is a bit late. You could do that in uclamp_rq_inc() maybe? That's probably better. Just to be sure ...we want this feature (an existing rt task gets its UCLAMP_MIN value set when the sysctl changes) because there could be rt tasks running before the sysctl is set? >> + >> if (!task_running(rq, p) && >> !test_tsk_need_resched(rq->curr) && >> p->nr_cpus_allowed > 1 && >> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h >> index 280a3c735935..337bf17b1a9d 100644 >> --- a/kernel/sched/sched.h >> +++ b/kernel/sched/sched.h >> @@ -2300,6 +2300,8 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {} >> #endif /* CONFIG_CPU_FREQ */ >> >> #ifdef CONFIG_UCLAMP_TASK >> +void uclamp_rt_sync_default_util_min(struct task_struct *p); >> + >> unsigned int uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id); >> >> static __always_inline >> @@ -2330,6 +2332,8 @@ static inline unsigned int uclamp_util(struct rq *rq, unsigned int util) >> return uclamp_util_with(rq, util, NULL); >> } >> #else /* CONFIG_UCLAMP_TASK */ >> +void uclamp_rt_sync_default_util_min(struct task_struct *p) {} -void uclamp_rt_sync_default_util_min(struct task_struct *p) {} +static inline void uclamp_rt_sync_default_util_min(struct task_struct *p) {} [...]