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[209.132.180.67]) by mx.google.com with ESMTP id 2-v6si15385624pfd.39.2018.08.06.09.44.56; Mon, 06 Aug 2018 09:45:10 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387477AbeHFSuj (ORCPT + 99 others); Mon, 6 Aug 2018 14:50:39 -0400 Received: from foss.arm.com ([217.140.101.70]:41792 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727561AbeHFSui (ORCPT ); Mon, 6 Aug 2018 14:50:38 -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 0A31880D; Mon, 6 Aug 2018 09:40:45 -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 3CF563F5D0; Mon, 6 Aug 2018 09:40:42 -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 , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan Subject: [PATCH v3 05/14] sched/cpufreq: uclamp: add utilization clamping for FAIR tasks Date: Mon, 6 Aug 2018 17:39:37 +0100 Message-Id: <20180806163946.28380-6-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180806163946.28380-1-patrick.bellasi@arm.com> References: <20180806163946.28380-1-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: Dietmar Eggemann Cc: Morten Rasmussen Cc: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org --- 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 | 71 ++++++++++++++++++++++++++++++++ 2 files changed, 92 insertions(+), 2 deletions(-) diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 3fffad3bc8a8..a7affc729c25 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(cpu_of(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 currently 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(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 c9df61d39a03..bb305e3d5737 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2293,6 +2293,77 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {} #endif /* CONFIG_CPU_FREQ */ +/** + * uclamp_none: default value for a clamp + * + * This returns the default value for each clamp + * - 0 for a min utilization clamp + * - SCHED_CAPACITY_SCALE for a max utilization clamp + * + * Return: the default value for a given utilization clamp + */ +static inline unsigned int uclamp_none(int clamp_id) +{ + if (clamp_id == UCLAMP_MIN) + return 0; + return SCHED_CAPACITY_SCALE; +} + +#ifdef CONFIG_UCLAMP_TASK +/** + * uclamp_value: get the current CPU's utilization clamp value + * @cpu: the CPU 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(unsigned int cpu, int clamp_id) +{ + struct uclamp_cpu *uc_cpu = &cpu_rq(cpu)->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 + * @cpu: the CPU 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(unsigned int cpu, unsigned int util) +{ + unsigned int min_util = uclamp_value(cpu, UCLAMP_MIN); + unsigned int max_util = uclamp_value(cpu, UCLAMP_MAX); + + return clamp(util, min_util, max_util); +} +#else /* CONFIG_UCLAMP_TASK */ +static inline unsigned int uclamp_value(unsigned int cpu, int clamp_id) +{ + return uclamp_none(clamp_id); +} + +static inline unsigned int uclamp_util(unsigned int cpu, 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