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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 B3435C433F5 for ; Tue, 28 Aug 2018 13:56:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6E5B22087C for ; Tue, 28 Aug 2018 13:56:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6E5B22087C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728144AbeH1Rq7 (ORCPT ); Tue, 28 Aug 2018 13:46:59 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:38486 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726439AbeH1Rq6 (ORCPT ); Tue, 28 Aug 2018 13:46:58 -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 BC5F81682; Tue, 28 Aug 2018 06:54:17 -0700 (PDT) Received: from e110439-lin.Cambridge.arm.com (e110439-lin.emea.arm.com [10.4.12.126]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CAF4C3F5BD; Tue, 28 Aug 2018 06:54:14 -0700 (PDT) From: Patrick Bellasi To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , Tejun Heo , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Paul Turner , Quentin Perret , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan Subject: [PATCH v4 06/16] sched/cpufreq: uclamp: add utilization clamping for FAIR tasks Date: Tue, 28 Aug 2018 14:53:14 +0100 Message-Id: <20180828135324.21976-7-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180828135324.21976-1-patrick.bellasi@arm.com> References: <20180828135324.21976-1-patrick.bellasi@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Each time a frequency update is required via schedutil, a frequency is selected to (possibly) satisfy the utilization reported by the CFS class. However, when utilization clamping is in use, the frequency selection should consider the requirements suggested by userspace, for example, to: - boost tasks which are directly affecting the user experience by running them at least at a minimum "required" frequency - cap low priority tasks not directly affecting the user experience by running them only up to a maximum "allowed" frequency These constraints are meant to support a per-task based tuning of the frequency selection thus allowing to have a fine grained definition of performance boosting vs energy saving strategies in kernel space. Let's add the required support to clamp the utilization generated by FAIR tasks within the boundaries defined by their aggregated utilization clamp constraints. On each CPU the aggregated clamp values are obtained by considering the maximum of the {min,max}_util values for each task. This max aggregation responds to the goal of not penalizing, for example, high boosted (i.e. more important for the user-experience) CFS tasks which happens to be co-scheduled with high capped (i.e. less important for the user-experience) CFS tasks. For FAIR tasks both the utilization as well as the IOWait boost values are clamped according to the CPU aggregated utilization clamp constraints. The default values for boosting and capping are defined to be: - util_min: 0 - util_max: SCHED_CAPACITY_SCALE which means that by default no boosting/capping is enforced on FAIR tasks, and thus the frequency will be selected considering the actual utilization value of each CPU. Signed-off-by: Patrick Bellasi Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Rafael J. Wysocki Cc: Viresh Kumar Cc: Suren Baghdasaryan Cc: Todd Kjos Cc: Joel Fernandes Cc: Juri Lelli Cc: Quentin Perret Cc: Dietmar Eggemann Cc: Morten Rasmussen Cc: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org --- Changes in v4: Message-ID: - use *rq instead of cpu for both uclamp_util() and uclamp_value() Message-ID: <20180816135300.GC2960@e110439-lin> - remove uclamp_value() which is never used outside CONFIG_UCLAMP_TASK Others: - rebased on v4.19-rc1 Changes in v3: Message-ID: - rename UCLAMP_NONE into UCLAMP_NOT_VALID Others: - rebased on tip/sched/core Changes in v2: - rebased on v4.18-rc4 --- kernel/sched/cpufreq_schedutil.c | 23 +++++++++++++-- kernel/sched/sched.h | 50 ++++++++++++++++++++++++++++++++ 2 files changed, 71 insertions(+), 2 deletions(-) diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 3fffad3bc8a8..949082555ee8 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -222,8 +222,13 @@ static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu) * CFS tasks and we use the same metric to track the effective * utilization (PELT windows are synchronized) we can directly add them * to obtain the CPU's actual utilization. + * + * CFS utilization can be boosted or capped, depending on utilization + * clamp constraints configured for currently RUNNABLE tasks. */ util = cpu_util_cfs(rq); + if (util) + util = uclamp_util(rq, util); util += cpu_util_rt(rq); /* @@ -307,6 +312,7 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, unsigned int flags) { bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT; + unsigned int max_boost; /* Reset boost if the CPU appears to have been idle enough */ if (sg_cpu->iowait_boost && @@ -322,11 +328,24 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, return; sg_cpu->iowait_boost_pending = true; + /* + * Boost FAIR tasks only up to the CPU clamped utilization. + * + * Since DL tasks have a much more advanced bandwidth control, it's + * safe to assume that IO boost does not apply to those tasks. + * Instead, since RT tasks are not utiliation clamped, we don't want + * to apply clamping on IO boost while there is blocked RT + * utilization. + */ + max_boost = sg_cpu->iowait_boost_max; + if (!cpu_util_rt(cpu_rq(sg_cpu->cpu))) + max_boost = uclamp_util(cpu_rq(sg_cpu->cpu), max_boost); + /* Double the boost at each request */ if (sg_cpu->iowait_boost) { sg_cpu->iowait_boost <<= 1; - if (sg_cpu->iowait_boost > sg_cpu->iowait_boost_max) - sg_cpu->iowait_boost = sg_cpu->iowait_boost_max; + if (sg_cpu->iowait_boost > max_boost) + sg_cpu->iowait_boost = max_boost; return; } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 411635c4c09a..1b05b38b1081 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2293,6 +2293,56 @@ static inline unsigned int uclamp_none(int clamp_id) return SCHED_CAPACITY_SCALE; } +#ifdef CONFIG_UCLAMP_TASK +/** + * uclamp_value: get the current CPU's utilization clamp value + * @rq: the CPU's RQ to consider + * @clamp_id: the utilization clamp index (i.e. min or max utilization) + * + * The utilization clamp value for a CPU depends on its set of currently + * RUNNABLE tasks and their specific util_{min,max} constraints. + * A max aggregated value is tracked for each CPU and returned by this + * function. + * + * Return: the current value for the specified CPU and clamp index + */ +static inline unsigned int uclamp_value(struct rq *rq, int clamp_id) +{ + struct uclamp_cpu *uc_cpu = &rq->uclamp; + + if (uc_cpu->value[clamp_id] == UCLAMP_NOT_VALID) + return uclamp_none(clamp_id); + + return uc_cpu->value[clamp_id]; +} + +/** + * clamp_util: clamp a utilization value for a specified CPU + * @rq: the CPU's RQ to get the clamp values from + * @util: the utilization signal to clamp + * + * Each CPU tracks util_{min,max} clamp values depending on the set of its + * currently RUNNABLE tasks. Given a utilization signal, i.e a signal in + * the [0..SCHED_CAPACITY_SCALE] range, this function returns a clamped + * utilization signal considering the current clamp values for the + * specified CPU. + * + * Return: a clamped utilization signal for a given CPU. + */ +static inline unsigned int uclamp_util(struct rq *rq, unsigned int util) +{ + unsigned int min_util = uclamp_value(rq, UCLAMP_MIN); + unsigned int max_util = uclamp_value(rq, UCLAMP_MAX); + + return clamp(util, min_util, max_util); +} +#else /* CONFIG_UCLAMP_TASK */ +static inline unsigned int uclamp_util(struct rq *rq, unsigned int util) +{ + return util; +} +#endif /* CONFIG_UCLAMP_TASK */ + #ifdef arch_scale_freq_capacity # ifndef arch_scale_freq_invariant # define arch_scale_freq_invariant() true -- 2.18.0