From patchwork Fri Feb 8 10:05:46 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Bellasi X-Patchwork-Id: 10802621 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2154614E1 for ; Fri, 8 Feb 2019 10:06:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0FE5F2DC81 for ; Fri, 8 Feb 2019 10:06:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0381A2DCD4; Fri, 8 Feb 2019 10:06:40 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 94F252DC81 for ; Fri, 8 Feb 2019 10:06:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727713AbfBHKGi (ORCPT ); Fri, 8 Feb 2019 05:06:38 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:47570 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726598AbfBHKGh (ORCPT ); Fri, 8 Feb 2019 05:06:37 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A481FA78; Fri, 8 Feb 2019 02:06:36 -0800 (PST) Received: from e110439-lin.cambridge.arm.com (e110439-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8DAE43F557; Fri, 8 Feb 2019 02:06:33 -0800 (PST) From: Patrick Bellasi To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-api@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , Tejun Heo , "Rafael J . Wysocki" , Vincent Guittot , Viresh Kumar , Paul Turner , Quentin Perret , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan Subject: [PATCH v7 07/15] sched/core: uclamp: Set default clamps for RT tasks Date: Fri, 8 Feb 2019 10:05:46 +0000 Message-Id: <20190208100554.32196-8-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190208100554.32196-1-patrick.bellasi@arm.com> References: <20190208100554.32196-1-patrick.bellasi@arm.com> MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP By default FAIR tasks start without clamps, i.e. neither boosted nor capped, and they run at the best frequency matching their utilization demand. This default behavior does not fit RT tasks which instead are expected to run at the maximum available frequency, if not otherwise required by explicitly capping them. Enforce the correct behavior for RT tasks by setting util_min to max whenever: 1. a task is switched to the RT class and it does not already have a user-defined clamp value assigned. 2. a task is forked from a parent with RESET_ON_FORK set. NOTE: utilization clamp values are cross scheduling class attributes and thus they are never changed/reset once a value has been explicitly defined from user-space. Signed-off-by: Patrick Bellasi Cc: Ingo Molnar Cc: Peter Zijlstra --- kernel/sched/core.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8b282616e9c9..569564012ddc 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1049,6 +1049,28 @@ static int uclamp_validate(struct task_struct *p, static void __setscheduler_uclamp(struct task_struct *p, const struct sched_attr *attr) { + unsigned int clamp_id; + + /* + * On scheduling class change, reset to default clamps for tasks + * without a task-specific value. + */ + for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) { + unsigned int clamp_value = uclamp_none(clamp_id); + struct uclamp_se *uc_se = &p->uclamp[clamp_id]; + + /* Keep using defined clamps across class changes */ + if (uc_se->user_defined) + continue; + + /* By default, RT tasks always get 100% boost */ + if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) + clamp_value = uclamp_none(UCLAMP_MAX); + + uc_se->bucket_id = uclamp_bucket_id(clamp_value); + uc_se->value = clamp_value; + } + if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP))) return; @@ -1087,6 +1109,10 @@ static void uclamp_fork(struct task_struct *p, bool reset) for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) { unsigned int clamp_value = uclamp_none(clamp_id); + /* By default, RT tasks always get 100% boost */ + if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) + clamp_value = uclamp_none(UCLAMP_MAX); + p->uclamp[clamp_id].user_defined = false; p->uclamp[clamp_id].value = clamp_value; p->uclamp[clamp_id].bucket_id = uclamp_bucket_id(clamp_value);