Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753370AbcJCQtL (ORCPT ); Mon, 3 Oct 2016 12:49:11 -0400 Received: from mga14.intel.com ([192.55.52.115]:41403 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752815AbcJCQtC (ORCPT ); Mon, 3 Oct 2016 12:49:02 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,438,1473145200"; d="scan'208";a="175880957" Date: Mon, 3 Oct 2016 09:49:01 -0700 From: Tim Chen To: Nilay Vaish Cc: Srinivas Pandruvada , rjw@rjwysocki.net, tglx@linutronix.de, mingo@redhat.com, bp@suse.de, x86 , linux-pm@vger.kernel.org, Linux Kernel list , linux-acpi@vger.kernel.org, peterz@infradead.org, jolsa@redhat.com Subject: Re: [PATCH v5 1/9] sched: Extend scheduler's asym packing Message-ID: <20161003164901.GA14994@linux.intel.com> Reply-To: tim.c.chen@linux.intel.com References: <1475322326-160112-1-git-send-email-srinivas.pandruvada@linux.intel.com> <1475322326-160112-2-git-send-email-srinivas.pandruvada@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.7.0 (2016-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6145 Lines: 190 On Sat, Oct 01, 2016 at 11:38:04AM -0500, Nilay Vaish wrote: > On 1 October 2016 at 06:45, Srinivas Pandruvada > wrote: > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > index e86c4a5..08135ca 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -6237,7 +6237,25 @@ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) > > WARN_ON(!sg); > > > > do { > > + int cpu, max_cpu = -1, prev_cpu = -1; > > + > > sg->group_weight = cpumask_weight(sched_group_cpus(sg)); > > + > > + if (!(sd->flags & SD_ASYM_PACKING)) > > + goto next; > > + > > + for_each_cpu(cpu, sched_group_cpus(sg)) { > > + if (prev_cpu < 0) { > > + prev_cpu = cpu; > > + max_cpu = cpu; > > It seems that you can drop prev_cpu and put the check on max_cpu instead. > The usage of prev_cpu was an artifact of the evolution of this patch. It can indeed be dropped and I've updated this change in the patch below. Thanks. Tim --->8--- commit 90955f87f228ee2fe7eeffcab851eb3141a783b4 Author: Tim Chen Subject: [PATCH v5 1/9 update] sched: Extend scheduler's asym packing sched: Extend scheduler's asym packing We generalize the scheduler's asym packing to provide an ordering of the cpu beyond just the cpu number. This allows the use of the ASYM_PACKING scheduler machinery to move loads to preferred CPU in a sched domain. The preference is defined with the cpu priority given by arch_asym_cpu_priority(cpu). We also record the most preferred cpu in a sched group when we build the cpu's capacity for fast lookup of preferred cpu during load balancing. Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Srinivas Pandruvada diff --git a/include/linux/sched.h b/include/linux/sched.h index 62c68e5..aeea288 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1052,6 +1052,8 @@ static inline int cpu_numa_flags(void) } #endif +int arch_asym_cpu_priority(int cpu); + struct sched_domain_attr { int relax_domain_level; }; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e86c4a5..b2e22de 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6237,7 +6237,22 @@ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) WARN_ON(!sg); do { + int cpu, max_cpu = -1; + sg->group_weight = cpumask_weight(sched_group_cpus(sg)); + + if (!(sd->flags & SD_ASYM_PACKING)) + goto next; + + for_each_cpu(cpu, sched_group_cpus(sg)) { + if (max_cpu < 0) + max_cpu = cpu; + else if (sched_asym_prefer(cpu, max_cpu)) + max_cpu = cpu; + } + sg->asym_prefer_cpu = max_cpu; + +next: sg = sg->next; } while (sg != sd->groups); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 039de34..8e2a078 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -100,6 +100,16 @@ const_debug unsigned int sysctl_sched_migration_cost = 500000UL; */ unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; +#ifdef CONFIG_SMP +/* + * For asym packing, by default the lower numbered cpu has higher priority. + */ +int __weak arch_asym_cpu_priority(int cpu) +{ + return -cpu; +} +#endif + #ifdef CONFIG_CFS_BANDWIDTH /* * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool @@ -6862,16 +6872,18 @@ static bool update_sd_pick_busiest(struct lb_env *env, if (env->idle == CPU_NOT_IDLE) return true; /* - * ASYM_PACKING needs to move all the work to the lowest - * numbered CPUs in the group, therefore mark all groups - * higher than ourself as busy. + * ASYM_PACKING needs to move all the work to the highest + * prority CPUs in the group, therefore mark all groups + * of lower priority than ourself as busy. */ - if (sgs->sum_nr_running && env->dst_cpu < group_first_cpu(sg)) { + if (sgs->sum_nr_running && + sched_asym_prefer(env->dst_cpu, sg->asym_prefer_cpu)) { if (!sds->busiest) return true; - /* Prefer to move from highest possible cpu's work */ - if (group_first_cpu(sds->busiest) < group_first_cpu(sg)) + /* Prefer to move from lowest priority cpu's work */ + if (sched_asym_prefer(sds->busiest->asym_prefer_cpu, + sg->asym_prefer_cpu)) return true; } @@ -7023,8 +7035,8 @@ static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) if (!sds->busiest) return 0; - busiest_cpu = group_first_cpu(sds->busiest); - if (env->dst_cpu > busiest_cpu) + busiest_cpu = sds->busiest->asym_prefer_cpu; + if (sched_asym_prefer(busiest_cpu, env->dst_cpu)) return 0; env->imbalance = DIV_ROUND_CLOSEST( @@ -7365,10 +7377,11 @@ static int need_active_balance(struct lb_env *env) /* * ASYM_PACKING needs to force migrate tasks from busy but - * higher numbered CPUs in order to pack all tasks in the - * lowest numbered CPUs. + * lower priority CPUs in order to pack all tasks in the + * highest priority CPUs. */ - if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu) + if ((sd->flags & SD_ASYM_PACKING) && + sched_asym_prefer(env->dst_cpu, env->src_cpu)) return 1; } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c64fc51..b6f449d 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -532,6 +532,11 @@ struct dl_rq { #ifdef CONFIG_SMP +static inline bool sched_asym_prefer(int a, int b) +{ + return arch_asym_cpu_priority(a) > arch_asym_cpu_priority(b); +} + /* * We add the notion of a root-domain which will be used to define per-domain * variables. Each exclusive cpuset essentially defines an island domain by @@ -884,6 +889,7 @@ struct sched_group { unsigned int group_weight; struct sched_group_capacity *sgc; + int asym_prefer_cpu; /* cpu of highest priority in group */ /* * The CPUs this group covers.