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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 EF149C433E6 for ; Tue, 26 Jan 2021 20:36:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C224522B3F for ; Tue, 26 Jan 2021 20:36:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727175AbhAZFK0 (ORCPT ); Tue, 26 Jan 2021 00:10:26 -0500 Received: from outbound-smtp25.blacknight.com ([81.17.249.193]:36159 "EHLO outbound-smtp25.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726703AbhAYJcc (ORCPT ); Mon, 25 Jan 2021 04:32:32 -0500 Received: from mail.blacknight.com (pemlinmail01.blacknight.ie [81.17.254.10]) by outbound-smtp25.blacknight.com (Postfix) with ESMTPS id 00B59CAFD0 for ; Mon, 25 Jan 2021 08:59:10 +0000 (GMT) Received: (qmail 12136 invoked from network); 25 Jan 2021 08:59:10 -0000 Received: from unknown (HELO stampy.112glenside.lan) (mgorman@techsingularity.net@[84.203.22.4]) by 81.17.254.9 with ESMTPA; 25 Jan 2021 08:59:10 -0000 From: Mel Gorman To: Peter Zijlstra , Ingo Molnar Cc: Vincent Guittot , Li Aubrey , Qais Yousef , LKML , Mel Gorman Subject: [PATCH 4/4] sched/fair: Merge select_idle_core/cpu() Date: Mon, 25 Jan 2021 08:59:09 +0000 Message-Id: <20210125085909.4600-5-mgorman@techsingularity.net> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210125085909.4600-1-mgorman@techsingularity.net> References: <20210125085909.4600-1-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra From: Peter Zijlstra (Intel) Both select_idle_core() and select_idle_cpu() do a loop over the same cpumask. Observe that by clearing the already visited CPUs, we can fold the iteration and iterate a core at a time. All we need to do is remember any non-idle CPU we encountered while scanning for an idle core. This way we'll only iterate every CPU once. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Mel Gorman --- kernel/sched/fair.c | 101 ++++++++++++++++++++++++++------------------ 1 file changed, 61 insertions(+), 40 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index fe587350ea14..52a650aa2108 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6006,6 +6006,14 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p return new_cpu; } +static inline int __select_idle_cpu(int cpu) +{ + if (available_idle_cpu(cpu) || sched_idle_cpu(cpu)) + return cpu; + + return -1; +} + #ifdef CONFIG_SCHED_SMT DEFINE_STATIC_KEY_FALSE(sched_smt_present); EXPORT_SYMBOL_GPL(sched_smt_present); @@ -6064,48 +6072,51 @@ void __update_idle_core(struct rq *rq) * there are no idle cores left in the system; tracked through * sd_llc->shared->has_idle_cores and enabled through update_idle_core() above. */ -static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target) +static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu) { - struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask); - int core, cpu; + bool idle = true; + int cpu; if (!static_branch_likely(&sched_smt_present)) - return -1; - - if (!test_idle_cores(target, false)) - return -1; - - cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); + return __select_idle_cpu(core); - for_each_cpu_wrap(core, cpus, target) { - bool idle = true; - - for_each_cpu(cpu, cpu_smt_mask(core)) { - if (!available_idle_cpu(cpu)) { - idle = false; - break; + for_each_cpu(cpu, cpu_smt_mask(core)) { + if (!available_idle_cpu(cpu)) { + idle = false; + if (*idle_cpu == -1) { + if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, p->cpus_ptr)) { + *idle_cpu = cpu; + break; + } + continue; } + break; } - - if (idle) - return core; - - cpumask_andnot(cpus, cpus, cpu_smt_mask(core)); + if (*idle_cpu == -1 && cpumask_test_cpu(cpu, p->cpus_ptr)) + *idle_cpu = cpu; } - /* - * Failed to find an idle core; stop looking for one. - */ - set_idle_cores(target, 0); + if (idle) + return core; + cpumask_andnot(cpus, cpus, cpu_smt_mask(core)); return -1; } #else /* CONFIG_SCHED_SMT */ -static inline int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target) +static inline void set_idle_cores(int cpu, int val) { - return -1; +} + +static inline bool test_idle_cores(int cpu, bool def) +{ + return def; +} + +static inline int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu) +{ + return __select_idle_cpu(core); } #endif /* CONFIG_SCHED_SMT */ @@ -6118,10 +6129,11 @@ static inline int select_idle_core(struct task_struct *p, struct sched_domain *s static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int target) { struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask); + int i, cpu, idle_cpu = -1, nr = INT_MAX; + bool smt = test_idle_cores(target, false); + int this = smp_processor_id(); struct sched_domain *this_sd; u64 time; - int this = smp_processor_id(); - int cpu, nr = INT_MAX; this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc)); if (!this_sd) @@ -6129,7 +6141,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); - if (sched_feat(SIS_PROP)) { + if (sched_feat(SIS_PROP) && !smt) { u64 avg_cost, avg_idle, span_avg; /* @@ -6149,18 +6161,31 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t } for_each_cpu_wrap(cpu, cpus, target) { - if (!--nr) - return -1; - if (available_idle_cpu(cpu) || sched_idle_cpu(cpu)) - break; + if (smt) { + i = select_idle_core(p, cpu, cpus, &idle_cpu); + if ((unsigned int)i < nr_cpumask_bits) + return i; + + } else { + if (!--nr) + return -1; + i = __select_idle_cpu(cpu); + if ((unsigned int)i < nr_cpumask_bits) { + idle_cpu = i; + break; + } + } } - if (sched_feat(SIS_PROP)) { + if (smt) + set_idle_cores(this, false); + + if (sched_feat(SIS_PROP) && !smt) { time = cpu_clock(this) - time; update_avg(&this_sd->avg_scan_cost, time); } - return cpu; + return idle_cpu; } /* @@ -6289,10 +6314,6 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) if (!sd) return target; - i = select_idle_core(p, sd, target); - if ((unsigned)i < nr_cpumask_bits) - return i; - i = select_idle_cpu(p, sd, target); if ((unsigned)i < nr_cpumask_bits) return i; -- 2.26.2