From patchwork Fri Feb 8 10:05:53 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Bellasi X-Patchwork-Id: 10802627 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 C1A1C14E1 for ; Fri, 8 Feb 2019 10:07:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B18662DC81 for ; Fri, 8 Feb 2019 10:07:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A5BF52DCD4; Fri, 8 Feb 2019 10:07:14 +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 37CE32DC81 for ; Fri, 8 Feb 2019 10:07:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727847AbfBHKHB (ORCPT ); Fri, 8 Feb 2019 05:07:01 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:47694 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727841AbfBHKHB (ORCPT ); Fri, 8 Feb 2019 05:07:01 -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 2891FA78; Fri, 8 Feb 2019 02:07:00 -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 11B263F557; Fri, 8 Feb 2019 02:06:56 -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 14/15] sched/core: uclamp: Use TG's clamps to restrict TASK's clamps Date: Fri, 8 Feb 2019 10:05:53 +0000 Message-Id: <20190208100554.32196-15-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 When a task specific clamp value is configured via sched_setattr(2), this value is accounted in the corresponding clamp bucket every time the task is {en,de}qeued. However, when cgroups are also in use, the task specific clamp values could be restricted by the task_group (TG) clamp values. Update uclamp_cpu_inc() to aggregate task and TG clamp values. Every time a task is enqueued, it's accounted in the clamp_bucket defining the smaller clamp between the task specific value and its TG effective value. This allows to: 1. ensure cgroup clamps are always used to restrict task specific requests, i.e. boosted only up to the effective granted value or clamped at least to a certain value 2. implement a "nice-like" policy, where tasks are still allowed to request less then what enforced by their current TG This mimics what already happens for a task's CPU affinity mask when the task is also in a cpuset, i.e. cgroup attributes are always used to restrict per-task attributes. Do this by exploiting the concept of "effective" clamp, which is already used by a TG to track parent enforced restrictions. Apply task group clamp restrictions only to tasks belonging to a child group. While, for tasks in the root group or in an autogroup, only system defaults are enforced. Signed-off-by: Patrick Bellasi Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Tejun Heo --- kernel/sched/core.c | 42 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 41 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 35e9f06af08d..6f8f68d18d0f 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -823,10 +823,44 @@ static inline void uclamp_rq_update(struct rq *rq, unsigned int clamp_id, WRITE_ONCE(rq->uclamp[clamp_id].value, max_value); } +static inline bool +uclamp_tg_restricted(struct task_struct *p, unsigned int clamp_id, + unsigned int *clamp_value, unsigned int *bucket_id) +{ +#ifdef CONFIG_UCLAMP_TASK_GROUP + unsigned int clamp_max, bucket_max; + struct uclamp_se *tg_clamp; + + /* + * Tasks in an autogroup or the root task group are restricted by + * system defaults. + */ + if (task_group_is_autogroup(task_group(p))) + return false; + if (task_group(p) == &root_task_group) + return false; + + tg_clamp = &task_group(p)->uclamp[clamp_id]; + bucket_max = tg_clamp->effective.bucket_id; + clamp_max = tg_clamp->effective.value; + + if (!p->uclamp[clamp_id].user_defined || *clamp_value > clamp_max) { + *clamp_value = clamp_max; + *bucket_id = bucket_max; + } + + return true; +#else + return false; +#endif +} + /* * The effective clamp bucket index of a task depends on, by increasing * priority: * - the task specific clamp value, when explicitly requested from userspace + * - the task group effective clamp value, for tasks not either in the root + * group or in an autogroup * - the system default clamp value, defined by the sysadmin * * As a side effect, update the task's effective value: @@ -841,7 +875,13 @@ uclamp_effective_get(struct task_struct *p, unsigned int clamp_id, *bucket_id = p->uclamp[clamp_id].bucket_id; *clamp_value = p->uclamp[clamp_id].value; - /* Always apply system default restrictions */ + /* + * If we have task groups and we are running in a child group, system + * default are already affecting the group's clamp values. + */ + if (uclamp_tg_restricted(p, clamp_id, clamp_value, bucket_id)) + return; + if (unlikely(*clamp_value > uclamp_default[clamp_id].value)) { *clamp_value = uclamp_default[clamp_id].value; *bucket_id = uclamp_default[clamp_id].bucket_id;