From patchwork Thu Nov 9 16:41:14 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Bellasi X-Patchwork-Id: 118462 Delivered-To: patch@linaro.org Received: by 10.140.22.164 with SMTP id 33csp6815904qgn; Thu, 9 Nov 2017 08:41:43 -0800 (PST) X-Google-Smtp-Source: ABhQp+QMjW9En5mEXOfnO2bJ+WfpbEfG4gjtnDrRhELCGKX+1qH/bZ/Sn/VY8fCS/vUW1eqw5KlF X-Received: by 10.84.168.100 with SMTP id e91mr998314plb.430.1510245703350; Thu, 09 Nov 2017 08:41:43 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1510245703; cv=none; d=google.com; s=arc-20160816; b=Fh78s6lgjGhR4E36OJVeIv8kCaXyzvNOXi++OkP9lu3/0WBUJUNVmMQ9hc7nIh1Wfu Ok6TVLgWeB1cW9FWKAjNKRkV+drDE1YySqLnA3iP11oUWe26PKG4T6FSvVqlA1wuEBNt pQDCCI0KN78YrLnbcK6+OO1qHVxnY/uvpucXxV2fvlHkigkzXnpKIsbXERdRimriD6Vr wXI4t7gSPwweSkJxmCOYA1ct0no/d4IUgxXJsMgnDEQkkJEQH92W7yKeAIV76rjptNtn xBuJEFmjIRZwCK3tUCTPxOqSmtIE6TYZHZv5JqQUDtu/1vw5ixjDsqLuEmYtacDTuPXq 6weA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=nFtDdCaJEjvTDpwIkMZSRNO9Wo3MFMD097gWslC/r3U=; b=g9ZH2mr9UUobl4k2Km3DEDM5qPubGBL7kVEe4yhxEVnIs3Z0GqxvTvCA4EDE3GRmUG 2+PtsOEx9kJTnR7TMYZZa5xyfaB/dhQ30YjXbd85HP+Vif81g+8rPLX6+IKN0FrA12qE Vi/wFU0lgzQ2QKzveYgf9cjru7xajItS1+jwBFRL9snrX+JTSZfK7CYizbL+116aeUFy kmRo/Ni2dfHDslKzjVb3ouKs2iOWKLbs2gaM0vVm8yp6uLrAsxzXUt31qjNVzvmpjaFS WbnlDyh79o5LhXWzqW72iEqFiM9/wDWUkKkwdTU5yNyjpI8VkHy9XmABLKzDP/3+A0NP YvKA== ARC-Authentication-Results: i=1; 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 Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id e9si6431324pgo.708.2017.11.09.08.41.43; Thu, 09 Nov 2017 08:41:43 -0800 (PST) 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 S1753480AbdKIQlk (ORCPT + 23 others); Thu, 9 Nov 2017 11:41:40 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:49210 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753007AbdKIQlh (ORCPT ); Thu, 9 Nov 2017 11:41:37 -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 808B315A2; Thu, 9 Nov 2017 08:41:37 -0800 (PST) Received: from e110439-lin.cambridge.arm.com (e110439-lin.cambridge.arm.com [10.1.210.68]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 4A93D3F3DF; Thu, 9 Nov 2017 08:41:35 -0800 (PST) From: Patrick Bellasi To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Paul Turner , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes Subject: [PATCH 1/4] sched/fair: always used unsigned long for utilization Date: Thu, 9 Nov 2017 16:41:14 +0000 Message-Id: <20171109164117.19401-2-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171109164117.19401-1-patrick.bellasi@arm.com> References: <20171109164117.19401-1-patrick.bellasi@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Utilization and capacity are tracked as unsigned long, however some functions using them returns an int which is ultimately assigned back to unsigned long variables. Since there is not scope on using a different and signed type, this consolidate the signature of functions returning utilization to always use the native type. As well as improving code consistency this is expected also benefits code paths where utilizations should be clamped by voiding further type conversions or ugly type casts. Signed-off-by: Patrick Bellasi Reviewed-by: Chris Redpath Reviewed-by: Brendan Jackman Reviewed-by: Dietmar Eggemann Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Vincent Guittot Cc: Morten Rasmussen Cc: Dietmar Eggemann Cc: linux-kernel@vger.kernel.org --- kernel/sched/fair.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) -- 2.14.1 diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 5c09ddf8c832..83bc5d69fe3a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5438,8 +5438,8 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, return affine; } -static inline int task_util(struct task_struct *p); -static int cpu_util_wake(int cpu, struct task_struct *p); +static inline unsigned long task_util(struct task_struct *p); +static unsigned long cpu_util_wake(int cpu, struct task_struct *p); static unsigned long capacity_spare_wake(int cpu, struct task_struct *p) { @@ -5870,7 +5870,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) * capacity_orig) as it useful for predicting the capacity required after task * migrations (scheduler-driven DVFS). */ -static int cpu_util(int cpu) +static unsigned long cpu_util(int cpu) { unsigned long util = cpu_rq(cpu)->cfs.avg.util_avg; unsigned long capacity = capacity_orig_of(cpu); @@ -5878,7 +5878,7 @@ static int cpu_util(int cpu) return (util >= capacity) ? capacity : util; } -static inline int task_util(struct task_struct *p) +static inline unsigned long task_util(struct task_struct *p) { return p->se.avg.util_avg; } @@ -5887,7 +5887,7 @@ static inline int task_util(struct task_struct *p) * cpu_util_wake: Compute cpu utilization with any contributions from * the waking task p removed. */ -static int cpu_util_wake(int cpu, struct task_struct *p) +static unsigned long cpu_util_wake(int cpu, struct task_struct *p) { unsigned long util, capacity; From patchwork Thu Nov 9 16:41:15 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Bellasi X-Patchwork-Id: 118463 Delivered-To: patch@linaro.org Received: by 10.140.22.164 with SMTP id 33csp6816014qgn; Thu, 9 Nov 2017 08:41:49 -0800 (PST) X-Google-Smtp-Source: ABhQp+TjK3wYKCTCfTHuDpd6ZR/6PEjDyKzl8lQHV9VmwnzVXTgEajZYwEiEJgSuTZ+F+mMGKooI X-Received: by 10.84.131.111 with SMTP id 102mr1017304pld.178.1510245709342; Thu, 09 Nov 2017 08:41:49 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1510245709; cv=none; d=google.com; s=arc-20160816; b=fmU7Uu4QpORrQsFCM+YKt35qxmT1jiZOC9nSLQ4VSw6sHKNyHhjjylrYl6UKX8Lfvn 43ZMv5+S4zHGdF2m9BYTwAs3n/PDShcIk2DeMumOmr+h5smOJMztNF7Tex3XzlMLRtc9 Qs3/8Tc8xw3KZXOZso8QQ1GLSaqHdTqMy8LgzENS/Bjw2Y4xMlbxWr3Mxh+fOEKaNpWZ Jr2EmWDrWu+d7c2pqY0PKX2/vb8Cjo6cInXuRK2D0Ug0cQBAbXgLmepVYDaEAxMjUOzh o4BjW0WqeOaB1LFeRhnC/b3bEZAIF2cIDB3u0bl1Yobi8J+beX0xpT8CyGAaIhjK34F7 e5Ig== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=pkyWFvZvSp7wZqmzNlNeY5jRZmfIN16Nkm9rK/orS1w=; b=VAo8GskTICSjzvF/2T5mpCwDpyUIHOMm+yY+/k7Gvn+8XvBP6CMNrqxFUSYGATgngQ QcL4HFbYlJw3PmAickJWrAGMt1B86yhGFOdY0zQSaUxxQ1sVk+CLBzAtc1zjK9fu9Z+y VXbM/OWDhwQGm9QjefRwJhK6EsgTHMEeVbbwtDD3X4iIG0lgfVqlFgy3J80IWGHevyvD Oh2eje6or4vmqVMKamGIIyou41C99Wl9kKKHbOQTXtt4HxwDW53gY4J3DDndi/oQOPoy rKrLF/6lXDGdp3Gq2Y7n9NzkFb/uiTeVx+R/JgO5ulad1Pc5IeotNbCL3LBMoNtpU2O5 z8Tg== ARC-Authentication-Results: i=1; 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 Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id e9si6431324pgo.708.2017.11.09.08.41.49; Thu, 09 Nov 2017 08:41:49 -0800 (PST) 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 S1753551AbdKIQlq (ORCPT + 23 others); Thu, 9 Nov 2017 11:41:46 -0500 Received: from foss.arm.com ([217.140.101.70]:49222 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753007AbdKIQll (ORCPT ); Thu, 9 Nov 2017 11:41:41 -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 2936B1610; Thu, 9 Nov 2017 08:41:41 -0800 (PST) Received: from e110439-lin.cambridge.arm.com (e110439-lin.cambridge.arm.com [10.1.210.68]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C3AE13F3DF; Thu, 9 Nov 2017 08:41:38 -0800 (PST) From: Patrick Bellasi To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Paul Turner , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , linux-pm@vger.kernel.org Subject: [PATCH 2/4] sched/fair: add util_est on top of PELT Date: Thu, 9 Nov 2017 16:41:15 +0000 Message-Id: <20171109164117.19401-3-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171109164117.19401-1-patrick.bellasi@arm.com> References: <20171109164117.19401-1-patrick.bellasi@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The util_avg signal computed by PELT is too variable for some use-cases. For example, a big task waking up after a long sleep period will have its utilization almost completely decayed. This introduces some latency before schedutil will be able to pick the best frequency to run a task. The same issue can affect task placement. Indeed, since the task utilization is already decayed at wakeup, when the task is enqueued in a CPU, this can results in a CPU running a big task as being temporarily represented as being almost empty. This leads to a race condition where other tasks can be potentially allocated on a CPU which just started to run a big task which slept for a relatively long period. Moreover, the PELT utilization of a task can be updated every [ms], thus making it a continuously changing value for certain longer running tasks. This means that the instantaneous PELT utilization of a RUNNING task is not really meaningful to properly support scheduler decisions. For all these reasons, a more stable signal could probably do a better job of representing the expected/estimated utilization of a task/cfs_rq. Such a signal can be easily created on top of PELT by still using it as an estimator which produces values to be aggregated on meaningful events. This patch adds a simple implementation of util_est, a new signal built on top of PELT's util_avg where: util_est(task) = max(task::util_avg, f(task::util_avg@dequeue_times)) This allows to remember how big a task has been reported by PELT in its previous activations via the function: f(task::util_avg@dequeue_times). If a task should change its behavior and it runs even longer in a new activation, after a certain time its util_est will just track the original PELT signal (i.e. task::util_avg). The estimated utilization of cfs_rq is defined only for root ones. That's because the only sensible consumer of this signal are the scheduler and schedutil when looking for the overall CPU utilization due to FAIR tasks. For this reason, the estimated utilization or a root cfs_rq is simply defined as: util_est(cfs_rq) = max(cfs_rq::util_avg, cfs_rq::util_est_runnable) where: cfs_rq::util_est_runnable = sum(util_est(task)) for each RUNNABLE task on that root cfs_rq It's worth to note that the estimated utilization is tracked only for entities of interests, specifically: - Tasks: to better support tasks placement decisions - root cfs_rqs: to better both tasks placement decisions as well as to better support frequencies selection for a CPU Signed-off-by: Patrick Bellasi Reviewed-by: Brendan Jackman Reviewed-by: Dietmar Eggemann Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Rafael J. Wysocki Cc: Viresh Kumar Cc: Paul Turner Cc: Vincent Guittot Cc: Morten Rasmussen Cc: Dietmar Eggemann Cc: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org --- include/linux/sched.h | 21 ++++++++++ kernel/sched/debug.c | 4 ++ kernel/sched/fair.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++- kernel/sched/features.h | 5 +++ kernel/sched/sched.h | 1 + 5 files changed, 132 insertions(+), 1 deletion(-) -- 2.14.1 diff --git a/include/linux/sched.h b/include/linux/sched.h index fdf74f27acf1..bce77204c378 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -338,6 +338,21 @@ struct sched_avg { unsigned long util_avg; }; +/** + * Estimation Utilization for FAIR tasks. + * + * Support data structure to track an Exponential Weighted Moving Average + * (EWMA) of a FAIR task's utilization. New samples are added to the moving + * average each time a task completes an activation. Sample's weight is + * chosen so that the EWMA will be relatively insensitive to transient changes + * to the task's workload. + */ +struct util_est { + unsigned long last; + unsigned long ewma; +#define UTIL_EST_WEIGHT_SHIFT 2 +}; + struct sched_statistics { #ifdef CONFIG_SCHEDSTATS u64 wait_start; @@ -561,6 +576,12 @@ struct task_struct { const struct sched_class *sched_class; struct sched_entity se; + /* + * Since we use se.avg.util_avg to update util_est fields, + * this last can benefit from being close to se which + * also defines se.avg as cache aligned. + */ + struct util_est util_est; struct sched_rt_entity rt; #ifdef CONFIG_CGROUP_SCHED struct task_group *sched_task_group; diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 2f93e4a2d9f6..a4af385329b2 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -564,6 +564,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) cfs_rq->runnable_load_avg); SEQ_printf(m, " .%-30s: %lu\n", "util_avg", cfs_rq->avg.util_avg); + SEQ_printf(m, " .%-30s: %lu\n", "util_est_runnable", + cfs_rq->util_est_runnable); SEQ_printf(m, " .%-30s: %ld\n", "removed_load_avg", atomic_long_read(&cfs_rq->removed_load_avg)); SEQ_printf(m, " .%-30s: %ld\n", "removed_util_avg", @@ -1010,6 +1012,8 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns, P(se.avg.load_avg); P(se.avg.util_avg); P(se.avg.last_update_time); + P(util_est.ewma); + P(util_est.last); #endif P(policy); P(prio); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 83bc5d69fe3a..f14d199e81ed 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -739,6 +739,12 @@ void init_entity_runnable_average(struct sched_entity *se) sa->util_avg = 0; sa->util_sum = 0; /* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */ + + /* Utilization estimation */ + if (entity_is_task(se)) { + task_of(se)->util_est.ewma = 0; + task_of(se)->util_est.last = 0; + } } static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); @@ -4870,6 +4876,20 @@ static inline void hrtick_update(struct rq *rq) } #endif +static inline unsigned long task_util(struct task_struct *p); +static inline unsigned long task_util_est(struct task_struct *p); + +static inline void util_est_enqueue(struct task_struct *p) +{ + struct cfs_rq *cfs_rq = &task_rq(p)->cfs; + + if (!sched_feat(UTIL_EST)) + return; + + /* Update root cfs_rq's estimated utilization */ + cfs_rq->util_est_runnable += task_util_est(p); +} + /* * The enqueue_task method is called before nr_running is * increased. Here we update the fair scheduling stats and @@ -4922,9 +4942,84 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) if (!se) add_nr_running(rq, 1); + util_est_enqueue(p); hrtick_update(rq); } +static inline void util_est_dequeue(struct task_struct *p, int flags) +{ + struct cfs_rq *cfs_rq = &task_rq(p)->cfs; + unsigned long util_last = task_util(p); + bool sleep = flags & DEQUEUE_SLEEP; + unsigned long ewma; + long util_est; + + if (!sched_feat(UTIL_EST)) + return; + + /* + * Update root cfs_rq's estimated utilization + * + * If *p is the last task then the root cfs_rq's estimated utilization + * of a CPU is 0 by definition. + * + * Otherwise, in removing *p's util_est from its cfs_rq's + * util_est_runnable we should account for cases where this last + * activation of *p was longer then the previous ones. + * Also in these cases we need to set 0 the estimated utilization for + * the CPU. + */ + if (cfs_rq->nr_running > 0) { + util_est = cfs_rq->util_est_runnable; + util_est -= task_util_est(p); + if (util_est < 0) + util_est = 0; + cfs_rq->util_est_runnable = util_est; + } else { + cfs_rq->util_est_runnable = 0; + } + + /* + * Skip update of task's estimated utilization when the task has not + * yet completed an activation, e.g. being migrated. + */ + if (!sleep) + return; + + /* + * Skip update of task's estimated utilization when its EWMA is already + * ~1% close to its last activation value. + */ + util_est = p->util_est.ewma; + if (abs(util_est - util_last) <= (SCHED_CAPACITY_SCALE / 100)) + return; + + /* + * Update Task's estimated utilization + * + * When *p completes an activation we can consolidate another sample + * about the task size. This is done by storing the last PELT value + * for this task and using this value to load another sample in the + * exponential weighted moving average: + * + * ewma(t) = w * task_util(p) + (1 - w) ewma(t-1) + * = w * task_util(p) + ewma(t-1) - w * ewma(t-1) + * = w * (task_util(p) + ewma(t-1) / w - ewma(t-1)) + * + * Where 'w' is the weight of new samples, which is configured to be + * 0.25, thus making w=1/4 + */ + p->util_est.last = util_last; + ewma = p->util_est.ewma; + if (likely(ewma != 0)) { + ewma = util_last + (ewma << UTIL_EST_WEIGHT_SHIFT) - ewma; + ewma >>= UTIL_EST_WEIGHT_SHIFT; + } else { + ewma = util_last; + } + p->util_est.ewma = ewma; +} + static void set_next_buddy(struct sched_entity *se); /* @@ -4981,6 +5076,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) if (!se) sub_nr_running(rq, 1); + util_est_dequeue(p, flags); hrtick_update(rq); } @@ -5438,7 +5534,6 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, return affine; } -static inline unsigned long task_util(struct task_struct *p); static unsigned long cpu_util_wake(int cpu, struct task_struct *p); static unsigned long capacity_spare_wake(int cpu, struct task_struct *p) @@ -5883,6 +5978,11 @@ static inline unsigned long task_util(struct task_struct *p) return p->se.avg.util_avg; } +static inline unsigned long task_util_est(struct task_struct *p) +{ + return max(p->util_est.ewma, p->util_est.last); +} + /* * cpu_util_wake: Compute cpu utilization with any contributions from * the waking task p removed. diff --git a/kernel/sched/features.h b/kernel/sched/features.h index 9552fd5854bf..e9f312acc0d3 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -85,3 +85,8 @@ SCHED_FEAT(ATTACH_AGE_LOAD, true) SCHED_FEAT(WA_IDLE, true) SCHED_FEAT(WA_WEIGHT, true) SCHED_FEAT(WA_BIAS, true) + +/* + * UtilEstimation. Use estimated CPU utiliation. + */ +SCHED_FEAT(UTIL_EST, false) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index e1666b3e2fb2..3abd13e68655 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -444,6 +444,7 @@ struct cfs_rq { * CFS load tracking */ struct sched_avg avg; + unsigned long util_est_runnable; u64 runnable_load_sum; unsigned long runnable_load_avg; #ifdef CONFIG_FAIR_GROUP_SCHED From patchwork Thu Nov 9 16:41:16 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Bellasi X-Patchwork-Id: 118465 Delivered-To: patch@linaro.org Received: by 10.140.22.164 with SMTP id 33csp6816370qgn; Thu, 9 Nov 2017 08:42:12 -0800 (PST) X-Google-Smtp-Source: ABhQp+RQymCtuf/X3QUvreawTd+mQHtFezqHlk23SpoIVmqvpniW0gFj4/9xof4tBssQcaXSn7t+ X-Received: by 10.101.80.132 with SMTP id r4mr1009530pgp.428.1510245732800; Thu, 09 Nov 2017 08:42:12 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1510245732; cv=none; d=google.com; s=arc-20160816; b=vHxARhoQcOt/r7uD5kZtheF3A8kbeVCPW5HRICJhnBavqocOnPJ7RAHS9p0MQZg/K4 Wo8MjMnShd5ZOPGWEknul8m7+FZaayJ7WPEn7byQRpgBxutylnIIuFBY59nYizpPbMj5 FWN2I//Ync8iXNJ4syd5SyS4X8CapuwPOXyDkFZjEqf5aX0WaYI5Bg5h0jdLmn/qSZZs 6BP2mbwysSqAtrGX7gort12qvw5vX4vSWO/N6k0sqmLuBIYZG1JLtqrwYj0KRbpl+g1T fD8ACVMD0vUjPxZ9UPyFud1V1j5yyvMarkY+IVEgh3Bc9WPf6HtJv0vW3xt2EsxrGxEW AKXg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=qVUVZ2cS6UQYIOapviHUXO3bznUFJivkodQcsWFjHXw=; b=XcBlRamabEyhGoGESZv4oaXZxNy+d6FOMXSEdFmeorM8Q6aPtGRKiNP/iQMa2hqSap 1ok65LP8JsdkuBk850V4A/PxEIkMDkhFx64uf3g06UkjX/sL69ASjXqvFrtGZxwt9q7e j934cCfahjSJAisX9IrHKA3euIKAZ654O92KcVAcxVIwDoH26R9tkdlDq9t+2fCNs6wi 1Gtc0nn5dDC5SkY521j64A1Apt+ynY3lEOZaSrGdNnD7O2jfE4euNFDO0UPAzE7q1lz6 LqcqFctcN+N+7UmWSJgDM/vRq/h9rsxxFDuCRCgjaGvHR12h26X1eS0lJg9wt2Z01LbA YcbA== ARC-Authentication-Results: i=1; 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 Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id w12si6816071pgp.482.2017.11.09.08.42.12; Thu, 09 Nov 2017 08:42:12 -0800 (PST) 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 S1753726AbdKIQmL (ORCPT + 23 others); Thu, 9 Nov 2017 11:42:11 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:49242 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753288AbdKIQlo (ORCPT ); Thu, 9 Nov 2017 11:41:44 -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 9C0BF164F; Thu, 9 Nov 2017 08:41:44 -0800 (PST) Received: from e110439-lin.cambridge.arm.com (e110439-lin.cambridge.arm.com [10.1.210.68]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 42C2B3F3DF; Thu, 9 Nov 2017 08:41:42 -0800 (PST) From: Patrick Bellasi To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Paul Turner , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , linux-pm@vger.kernel.org Subject: [PATCH 3/4] sched/fair: use util_est in LB and WU paths Date: Thu, 9 Nov 2017 16:41:16 +0000 Message-Id: <20171109164117.19401-4-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171109164117.19401-1-patrick.bellasi@arm.com> References: <20171109164117.19401-1-patrick.bellasi@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When the scheduler looks at the CPU utilization, the current PELT value for a CPU is returned straight away. In certain scenarios this can have undesired side effects on task placement. For example, since the task utilization is decayed at wakeup time, when a long sleeping big task is enqueued it does not add immediately a significant contribution to the target CPU. As a result we generate a race condition where other tasks can be placed on the same CPU while is still considered relatively empty. In order to reduce these kind of race conditions, this patch introduces the required support to integrate the usage of the CPU's estimated utilization in cpu_util_wake as well as in update_sg_lb_stats. The estimated utilization of a CPU is defined to be the maximum between its PELT's utilization and the sum of the estimated utilization of the tasks currently RUNNABLE on that CPU. This allows to properly represent the expected utilization of a CPU which, for example it has just got a big task running since a long sleep period. Signed-off-by: Patrick Bellasi Reviewed-by: Brendan Jackman Reviewed-by: Dietmar Eggemann Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Rafael J. Wysocki Cc: Viresh Kumar Cc: Paul Turner Cc: Vincent Guittot Cc: Morten Rasmussen Cc: Dietmar Eggemann Cc: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org --- kernel/sched/fair.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 68 insertions(+), 6 deletions(-) -- 2.14.1 diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index f14d199e81ed..76626e1a7645 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5973,6 +5973,41 @@ static unsigned long cpu_util(int cpu) return (util >= capacity) ? capacity : util; } +/** + * cpu_util_est: estimated utilization for the specified CPU + * @cpu: the CPU to get the estimated utilization for + * + * The estimated utilization of a CPU is defined to be the maximum between its + * PELT's utilization and the sum of the estimated utilization of the tasks + * currently RUNNABLE on that CPU. + * + * This allows to properly represent the expected utilization of a CPU which + * has just got a big task running since a long sleep period. At the same time + * however it preserves the benefits of the "blocked load" in describing the + * potential for other tasks waking up on the same CPU. + * + * Return: the estimated utlization for the specified CPU + */ +static inline unsigned long cpu_util_est(int cpu) +{ + unsigned long util, util_est; + unsigned long capacity; + struct cfs_rq *cfs_rq; + + if (!sched_feat(UTIL_EST)) + return cpu_util(cpu); + + cfs_rq = &cpu_rq(cpu)->cfs; + util = cfs_rq->avg.util_avg; + util_est = cfs_rq->util_est_runnable; + util_est = max(util, util_est); + + capacity = capacity_orig_of(cpu); + util_est = min(util_est, capacity); + + return util_est; +} + static inline unsigned long task_util(struct task_struct *p) { return p->se.avg.util_avg; @@ -5989,16 +6024,43 @@ static inline unsigned long task_util_est(struct task_struct *p) */ static unsigned long cpu_util_wake(int cpu, struct task_struct *p) { - unsigned long util, capacity; + long util, util_est; /* Task has no contribution or is new */ if (cpu != task_cpu(p) || !p->se.avg.last_update_time) - return cpu_util(cpu); + return cpu_util_est(cpu); - capacity = capacity_orig_of(cpu); - util = max_t(long, cpu_rq(cpu)->cfs.avg.util_avg - task_util(p), 0); + /* Discount task's blocked util from CPU's util */ + util = cpu_util(cpu) - task_util(p); + util = max(util, 0L); - return (util >= capacity) ? capacity : util; + if (!sched_feat(UTIL_EST)) + return util; + + /* + * These are the main cases covered: + * - if *p is the only task sleeping on this CPU, then: + * cpu_util (== task_util) > util_est (== 0) + * and thus we return: + * cpu_util_wake = (cpu_util - task_util) = 0 + * + * - if other tasks are SLEEPING on the same CPU, which is just waking + * up, then: + * cpu_util >= task_util + * cpu_util > util_est (== 0) + * and thus we discount *p's blocked utilization to return: + * cpu_util_wake = (cpu_util - task_util) >= 0 + * + * - if other tasks are RUNNABLE on that CPU and + * util_est > cpu_util + * then we use util_est since it returns a more restrictive + * estimation of the spare capacity on that CPU, by just considering + * the expected utilization of tasks already runnable on that CPU. + */ + util_est = cpu_rq(cpu)->cfs.util_est_runnable; + util = max(util, util_est); + + return util; } /* @@ -7525,7 +7587,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, load = source_load(i, load_idx); sgs->group_load += load; - sgs->group_util += cpu_util(i); + sgs->group_util += cpu_util_est(i); sgs->sum_nr_running += rq->cfs.h_nr_running; nr_running = rq->nr_running; From patchwork Thu Nov 9 16:41:17 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Bellasi X-Patchwork-Id: 118464 Delivered-To: patch@linaro.org Received: by 10.140.22.164 with SMTP id 33csp6816157qgn; Thu, 9 Nov 2017 08:41:57 -0800 (PST) X-Google-Smtp-Source: ABhQp+TRm9l8DHGxWLHvmlKL9v8rJcxek/JoO18NYwwJRwMJi73UZf92SAVY7eATgj2Us+LNLGAo X-Received: by 10.99.158.17 with SMTP id s17mr1024800pgd.218.1510245717022; Thu, 09 Nov 2017 08:41:57 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1510245717; cv=none; d=google.com; s=arc-20160816; b=Jg3bV8J43KwvzyYgtamKOXjxW43MIZfim5XOzvsvaWXE2zeEGu3JOgFkIiI2x39O3V EJJv/VKA0jaVZtffzb12mia7Fsj4hTbBwHLH/p0m+ahzBIU+ZPMTGmpEsVctJ3j5NIla tJ/VjTgsSDeKdSC+wMpffvEef4+J+SQIfvJVylwOKMJbTcuGY0gNBEY6Mn13YmeM50+V 8y3TF2Cfe7sQctlgvmIPAsE1aGuKnBk0UllGcMGdcCDJaUEZQIwDwMABNjA2j1lKmZYH Vnr7tvIa/P8nhKXYh9OVpy3a1UFZuYsMxkgXR/W5kKZQEwo4/5IvhmYP46d0qCddSW/O 7H5Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=29DKg49i1ma6XeEBwDbATjytt/YzfRmPvJnXjkYYqzU=; b=vljhe1oc7cBhO1K4WuI44Z5FLiG0uc6QzARqCtPCd9N1Sy6lMuqsqNkPW3Je0HDDmd KDJLARgJzxaasdnb6ov4vWKUaE8d6jGy7tUGTQfcv+mhr3PzK7qObFmQhz1wqA+quF+f Rogd2NvEmZD5p8kBCEk0yHSCQZsz8fRvVNER3Rdz25qCgbePYuxA/UcV3aQfZAfOS1PA lgP8EbXBjBwnCEznzbx4xHZIUne5G8VSgzalVPzMBDXdlHI3E1z9p7xqZ18TIRdIvqp2 HGlAEXKHzpz9HuKV/xi2PlsiCiiH6tP45/TQH2jSXtY21Vss5roS/AUqOZQN42KlmYru I2OQ== ARC-Authentication-Results: i=1; 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 Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id e9si6431324pgo.708.2017.11.09.08.41.55; Thu, 09 Nov 2017 08:41:57 -0800 (PST) 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 S1753605AbdKIQlx (ORCPT + 23 others); Thu, 9 Nov 2017 11:41:53 -0500 Received: from foss.arm.com ([217.140.101.70]:49260 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753007AbdKIQls (ORCPT ); Thu, 9 Nov 2017 11:41:48 -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 114D51650; Thu, 9 Nov 2017 08:41:48 -0800 (PST) Received: from e110439-lin.cambridge.arm.com (e110439-lin.cambridge.arm.com [10.1.210.68]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id AC3D43F3DF; Thu, 9 Nov 2017 08:41:45 -0800 (PST) From: Patrick Bellasi To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Paul Turner , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , linux-pm@vger.kernel.org Subject: [PATCH 4/4] sched/cpufreq_schedutil: use util_est for OPP selection Date: Thu, 9 Nov 2017 16:41:17 +0000 Message-Id: <20171109164117.19401-5-patrick.bellasi@arm.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171109164117.19401-1-patrick.bellasi@arm.com> References: <20171109164117.19401-1-patrick.bellasi@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When schedutil looks at the CPU utilization, the current PELT value for that CPU is returned straight away. In certain scenarios this can have undesired side effects and delays on frequency selection. For example, since the task utilization is decayed at wakeup time, a long sleeping big task newly enqueued it does not add immediately a significant contribution to the target CPU. This introduces some latency before schedutil will be able to detect the best frequency required by that task. Moreover, the PELT signal building up time is function of the current frequency, because of the scale invariant load tracking support. Thus, starting from a lower frequency, the utilization build-up time will increase even more and further delays the selection of the actual frequency which better serves the task requirements. In order to reduce these kind of latencies, this patch integrates the usage of the CPU's estimated utilization in the sugov_get_util function. The estimated utilization of a CPU is defined to be the maximum between its PELT's utilization and the sum of the estimated utilization of each currently RUNNABLE task on that CPU. This allows to properly represent the expected utilization of a CPU which, for example, it has just got a big task running after a long sleep period, and ultimately it allows to select the best frequency to run a task right after its wakes up. Signed-off-by: Patrick Bellasi Reviewed-by: Brendan Jackman Reviewed-by: Dietmar Eggemann Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Rafael J. Wysocki Cc: Viresh Kumar Cc: Paul Turner Cc: Vincent Guittot Cc: Morten Rasmussen Cc: Dietmar Eggemann Cc: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org --- kernel/sched/cpufreq_schedutil.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) -- 2.14.1 diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 137733db6727..d72231e30d44 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -183,7 +183,11 @@ static void sugov_get_util(unsigned long *util, unsigned long *max, int cpu) cfs_max = arch_scale_cpu_capacity(NULL, cpu); - *util = min(rq->cfs.avg.util_avg, cfs_max); + *util = rq->cfs.avg.util_avg; + if (sched_feat(UTIL_EST)) + *util = max(*util, rq->cfs.util_est_runnable); + *util = min(*util, cfs_max); + *max = cfs_max; }