From patchwork Tue Oct 16 10:15:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Quentin Perret X-Patchwork-Id: 10643337 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 565E21057 for ; Tue, 16 Oct 2018 10:16:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 488462856D for ; Tue, 16 Oct 2018 10:16:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3CD6F29212; Tue, 16 Oct 2018 10:16:51 +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 CBEB92856D for ; Tue, 16 Oct 2018 10:16:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727298AbeJPSFq (ORCPT ); Tue, 16 Oct 2018 14:05:46 -0400 Received: from foss.arm.com ([217.140.101.70]:33962 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726760AbeJPSFq (ORCPT ); Tue, 16 Oct 2018 14:05:46 -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 74F43ED1; Tue, 16 Oct 2018 03:16:03 -0700 (PDT) Received: from queper01-lin.local (unknown [10.1.195.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 637C93F59C; Tue, 16 Oct 2018 03:15:59 -0700 (PDT) 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 v8 09/15] sched: Introduce sched_energy_present static key Date: Tue, 16 Oct 2018 11:15:07 +0100 Message-Id: <20181016101513.26919-10-quentin.perret@arm.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181016101513.26919-1-quentin.perret@arm.com> References: <20181016101513.26919-1-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 order to make sure Energy Aware Scheduling (EAS) will not impact systems where no Energy Model is available, introduce a static key guarding the access to EAS code. Since EAS is enabled on a per-root-domain basis, the static key is enabled when at least one root domain meets all conditions for EAS. Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Quentin Perret --- kernel/sched/sched.h | 4 ++++ kernel/sched/topology.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index cba77f619e4e..9d6cf58a8aff 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2278,3 +2278,7 @@ unsigned long scale_irq_capacity(unsigned long util, unsigned long irq, unsigned #else #define perf_domain_span(pd) NULL #endif + +#ifdef CONFIG_SMP +extern struct static_key_false sched_energy_present; +#endif diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 8f5efab1c058..58bfda46ac07 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -201,6 +201,7 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) return 1; } +DEFINE_STATIC_KEY_FALSE(sched_energy_present); #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) DEFINE_MUTEX(sched_energy_mutex); bool sched_energy_update; @@ -273,6 +274,35 @@ static void destroy_perf_domain_rcu(struct rcu_head *rp) free_pd(pd); } +static void sched_energy_start(int ndoms_new, cpumask_var_t doms_new[]) +{ + /* + * The conditions for EAS to start are checked during the creation of + * root domains. If one of them meets all conditions, it will have a + * non-null list of performance domains. + */ + while (ndoms_new) { + if (cpu_rq(cpumask_first(doms_new[ndoms_new - 1]))->rd->pd) + goto enable; + ndoms_new--; + } + + if (static_branch_unlikely(&sched_energy_present)) { + if (sched_debug()) + pr_info("%s: stopping EAS\n", __func__); + static_branch_disable_cpuslocked(&sched_energy_present); + } + + return; + +enable: + if (!static_branch_unlikely(&sched_energy_present)) { + if (sched_debug()) + pr_info("%s: starting EAS\n", __func__); + static_branch_enable_cpuslocked(&sched_energy_present); + } +} + /* * EAS can be used on a root domain if it meets all the following conditions: * 1. an Energy Model (EM) is available; @@ -2187,6 +2217,7 @@ void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], match3: ; } + sched_energy_start(ndoms_new, doms_new); #endif /* Remember the new sched domains: */