From patchwork Thu Jul 18 18:17:45 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Bellasi X-Patchwork-Id: 11049403 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 AE3D713B1 for ; Thu, 18 Jul 2019 18:19:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9FEC128820 for ; Thu, 18 Jul 2019 18:19:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 943AF28884; Thu, 18 Jul 2019 18:19:00 +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 2C4512883B for ; Thu, 18 Jul 2019 18:18:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728153AbfGRSSX (ORCPT ); Thu, 18 Jul 2019 14:18:23 -0400 Received: from foss.arm.com ([217.140.110.172]:33434 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391116AbfGRSSW (ORCPT ); Thu, 18 Jul 2019 14:18:22 -0400 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 ABE22152F; Thu, 18 Jul 2019 11:18:21 -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 056E03F71A; Thu, 18 Jul 2019 11:18:18 -0700 (PDT) From: Patrick Bellasi To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-api@vger.kernel.org, cgroups@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , Tejun Heo , "Rafael J . Wysocki" , Vincent Guittot , Viresh Kumar , Paul Turner , Michal Koutny , Quentin Perret , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan , Alessio Balsini Subject: [PATCH v12 3/6] sched/core: uclamp: Propagate system defaults to root group Date: Thu, 18 Jul 2019 19:17:45 +0100 Message-Id: <20190718181748.28446-4-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190718181748.28446-1-patrick.bellasi@arm.com> References: <20190718181748.28446-1-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 The clamp values are not tunable at the level of the root task group. That's for two main reasons: - the root group represents "system resources" which are always entirely available from the cgroup standpoint. - when tuning/restricting "system resources" makes sense, tuning must be done using a system wide API which should also be available when control groups are not. When a system wide restriction is available, cgroups should be aware of its value in order to know exactly how much "system resources" are available for the subgroups. Utilization clamping supports already the concepts of: - system defaults: which define the maximum possible clamp values usable by tasks. - effective clamps: which allows a parent cgroup to constraint (maybe temporarily) its descendants without losing the information related to the values "requested" from them. Exploit these two concepts and bind them together in such a way that, whenever system default are tuned, the new values are propagated to (possibly) restrict or relax the "effective" value of nested cgroups. Signed-off-by: Patrick Bellasi Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Tejun Heo --- Changes in v12: Message-ID: <20190716143417.us3xhksrsaxsl2ok@e110439-lin> - add missing RCU read locks across cpu_util_update_eff() call from uclamp_update_root_tg() --- kernel/sched/core.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 08f5a0c205c6..e9231b089d5c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1017,10 +1017,30 @@ static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) uclamp_rq_dec_id(rq, p, clamp_id); } +#ifdef CONFIG_UCLAMP_TASK_GROUP +static void cpu_util_update_eff(struct cgroup_subsys_state *css); +static void uclamp_update_root_tg(void) +{ + struct task_group *tg = &root_task_group; + + uclamp_se_set(&tg->uclamp_req[UCLAMP_MIN], + sysctl_sched_uclamp_util_min, false); + uclamp_se_set(&tg->uclamp_req[UCLAMP_MAX], + sysctl_sched_uclamp_util_max, false); + + rcu_read_lock(); + cpu_util_update_eff(&root_task_group.css); + rcu_read_unlock(); +} +#else +static void uclamp_update_root_tg(void) { } +#endif + int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { + bool update_root_tg = false; int old_min, old_max; int result; @@ -1043,12 +1063,17 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, if (old_min != sysctl_sched_uclamp_util_min) { uclamp_se_set(&uclamp_default[UCLAMP_MIN], sysctl_sched_uclamp_util_min, false); + update_root_tg = true; } if (old_max != sysctl_sched_uclamp_util_max) { uclamp_se_set(&uclamp_default[UCLAMP_MAX], sysctl_sched_uclamp_util_max, false); + update_root_tg = true; } + if (update_root_tg) + uclamp_update_root_tg(); + /* * Updating all the RUNNABLE task is expensive, keep it simple and do * just a lazy update at each next enqueue time.