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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 85C98C4360F for ; Tue, 2 Apr 2019 10:42:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 61264208E4 for ; Tue, 2 Apr 2019 10:42:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730173AbfDBKmr (ORCPT ); Tue, 2 Apr 2019 06:42:47 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:48408 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729935AbfDBKmp (ORCPT ); Tue, 2 Apr 2019 06:42:45 -0400 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 E13961688; Tue, 2 Apr 2019 03:42:44 -0700 (PDT) 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 C9D4A3F59C; Tue, 2 Apr 2019 03:42:41 -0700 (PDT) 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 v8 08/16] sched/core: uclamp: Set default clamps for RT tasks Date: Tue, 2 Apr 2019 11:41:44 +0100 Message-Id: <20190402104153.25404-9-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190402104153.25404-1-patrick.bellasi@arm.com> References: <20190402104153.25404-1-patrick.bellasi@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. the task is switched to the RT class and it does not already have a user-defined clamp value assigned. 2. an RT 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 bdebdabe9bc4..71c9dd6487b1 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1042,6 +1042,28 @@ 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) { + struct uclamp_se *uc_se = &p->uclamp_req[clamp_id]; + unsigned int clamp_value = uclamp_none(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; @@ -1077,6 +1099,10 @@ static void uclamp_fork(struct task_struct *p) 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_req[clamp_id].user_defined = false; p->uclamp_req[clamp_id].value = clamp_value; p->uclamp_req[clamp_id].bucket_id = uclamp_bucket_id(clamp_value); -- 2.20.1