From patchwork Mon Dec 3 09:56:26 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Quentin Perret X-Patchwork-Id: 10709025 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 C7E4813AD for ; Mon, 3 Dec 2018 09:57:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B89392AC64 for ; Mon, 3 Dec 2018 09:57:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AC4DF2AE2D; Mon, 3 Dec 2018 09:57:41 +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 319B22AC64 for ; Mon, 3 Dec 2018 09:57:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726315AbeLCJ5z (ORCPT ); Mon, 3 Dec 2018 04:57:55 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:32910 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725888AbeLCJ5y (ORCPT ); Mon, 3 Dec 2018 04:57:54 -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 348721682; Mon, 3 Dec 2018 01:57:35 -0800 (PST) Received: from queper01-lin.cambridge.arm.com (queper01-lin.cambridge.arm.com [10.1.195.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 185FA3F59C; Mon, 3 Dec 2018 01:57:30 -0800 (PST) From: Quentin Perret To: peterz@infradead.org, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Cc: gregkh@linuxfoundation.org, mingo@redhat.com, dietmar.eggemann@arm.com, morten.rasmussen@arm.com, chris.redpath@arm.com, patrick.bellasi@arm.com, valentin.schneider@arm.com, vincent.guittot@linaro.org, thara.gopinath@linaro.org, viresh.kumar@linaro.org, tkjos@google.com, joel@joelfernandes.org, smuckle@google.com, adharmap@codeaurora.org, skannan@codeaurora.org, pkondeti@codeaurora.org, juri.lelli@redhat.com, edubezval@gmail.com, srinivas.pandruvada@linux.intel.com, currojerez@riseup.net, javi.merino@kernel.org, quentin.perret@arm.com Subject: [PATCH v10 13/15] sched/fair: Introduce an energy estimation helper function Date: Mon, 3 Dec 2018 09:56:26 +0000 Message-Id: <20181203095628.11858-14-quentin.perret@arm.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181203095628.11858-1-quentin.perret@arm.com> References: <20181203095628.11858-1-quentin.perret@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 In preparation for the definition of an energy-aware wakeup path, introduce a helper function to estimate the consequence on system energy when a specific task wakes-up on a specific CPU. compute_energy() estimates the capacity state to be reached by all performance domains and estimates the consumption of each online CPU according to its Energy Model and its percentage of busy time. Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Quentin Perret --- kernel/sched/fair.c | 76 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c3b2dad72c9c..a20018ad9236 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6377,6 +6377,82 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu) return !task_fits_capacity(p, min_cap); } +/* + * Predicts what cpu_util(@cpu) would return if @p was migrated (and enqueued) + * to @dst_cpu. + */ +static unsigned long cpu_util_next(int cpu, struct task_struct *p, int dst_cpu) +{ + struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs; + unsigned long util_est, util = READ_ONCE(cfs_rq->avg.util_avg); + + /* + * If @p migrates from @cpu to another, remove its contribution. Or, + * if @p migrates from another CPU to @cpu, add its contribution. In + * the other cases, @cpu is not impacted by the migration, so the + * util_avg should already be correct. + */ + if (task_cpu(p) == cpu && dst_cpu != cpu) + sub_positive(&util, task_util(p)); + else if (task_cpu(p) != cpu && dst_cpu == cpu) + util += task_util(p); + + if (sched_feat(UTIL_EST)) { + util_est = READ_ONCE(cfs_rq->avg.util_est.enqueued); + + /* + * During wake-up, the task isn't enqueued yet and doesn't + * appear in the cfs_rq->avg.util_est.enqueued of any rq, + * so just add it (if needed) to "simulate" what will be + * cpu_util() after the task has been enqueued. + */ + if (dst_cpu == cpu) + util_est += _task_util_est(p); + + util = max(util, util_est); + } + + return min(util, capacity_orig_of(cpu)); +} + +/* + * compute_energy(): Estimates the energy that would be consumed if @p was + * migrated to @dst_cpu. compute_energy() predicts what will be the utilization + * landscape of the * CPUs after the task migration, and uses the Energy Model + * to compute what would be the energy if we decided to actually migrate that + * task. + */ +static long +compute_energy(struct task_struct *p, int dst_cpu, struct perf_domain *pd) +{ + long util, max_util, sum_util, energy = 0; + int cpu; + + for (; pd; pd = pd->next) { + max_util = sum_util = 0; + /* + * The capacity state of CPUs of the current rd can be driven by + * CPUs of another rd if they belong to the same performance + * domain. So, account for the utilization of these CPUs too + * by masking pd with cpu_online_mask instead of the rd span. + * + * If an entire performance domain is outside of the current rd, + * it will not appear in its pd list and will not be accounted + * by compute_energy(). + */ + for_each_cpu_and(cpu, perf_domain_span(pd), cpu_online_mask) { + util = cpu_util_next(cpu, p, dst_cpu); + util = schedutil_energy_util(cpu, util); + max_util = max(util, max_util); + sum_util += util; + } + + energy += em_pd_energy(pd->em_pd, max_util, sum_util); + } + + return energy; +} + /* * select_task_rq_fair: Select target runqueue for the waking task in domains * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,