From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753053Ab3F0QLi (ORCPT ); Thu, 27 Jun 2013 12:11:38 -0400 Received: from merlin.infradead.org ([205.233.59.134]:60971 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752648Ab3F0QLh (ORCPT ); Thu, 27 Jun 2013 12:11:37 -0400 Date: Thu, 27 Jun 2013 18:11:27 +0200 From: Peter Zijlstra To: Mel Gorman Cc: Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML Subject: Re: [PATCH 5/8] sched: Favour moving tasks towards the preferred node Message-ID: <20130627161127.GZ28407@twins.programming.kicks-ass.net> References: <1372257487-9749-1-git-send-email-mgorman@suse.de> <1372257487-9749-6-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1372257487-9749-6-git-send-email-mgorman@suse.de> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 26, 2013 at 03:38:04PM +0100, Mel Gorman wrote: > +/* Returns true if the destination node has incurred more faults */ > +static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env) > +{ > + int src_nid, dst_nid; > + > + if (!p->numa_faults || !(env->sd->flags & SD_NUMA)) > + return false; > + > + src_nid = cpu_to_node(env->src_cpu); > + dst_nid = cpu_to_node(env->dst_cpu); > + > + if (src_nid == dst_nid) > + return false; > + > + if (p->numa_migrate_seq < sysctl_numa_balancing_settle_count && > + p->numa_preferred_nid == dst_nid) > + return true; > + > + return false; > +} Also, until I just actually _read_ that function; I assumed it would compare p->numa_faults[src_nid] and p->numa_faults[dst_nid]. Because even when the dst_nid isn't the preferred nid; it might still have more pages than where we currently are. Idem with the proposed migrate_degrades_locality(). Something like so I suppose --- --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3969,6 +3969,7 @@ task_hot(struct task_struct *p, u64 now, return delta < (s64)sysctl_sched_migration_cost; } +#ifdef CONFIG_NUMA_BALANCING /* Returns true if the destination node has incurred more faults */ static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env) { @@ -3983,13 +3984,50 @@ static bool migrate_improves_locality(st if (src_nid == dst_nid) return false; - if (p->numa_migrate_seq < sysctl_numa_balancing_settle_count && - p->numa_preferred_nid == dst_nid) + if (p->numa_migrate_seq >= sysctl_numa_balancing_settle_count) + return false; + + if (p->numa_preferred_nid == dst_nid) + return true; + + if (p->numa_faults[src_nid] < p->numa_faults[dst_nid]) + return true; + + return false; +} + +static vool migrate_degrades_locality(struct task_struct *p, struct lb_env *env) +{ + int src_nid, dst_nid; + + if (!p->numa_faults || !(env->sd->flags & SD_NUMA)) + return false; + + src_nid = cpu_to_node(env->src_cpu); + dst_nid = cpu_to_node(env->dst_cpu); + + if (src_nid == dst_nid) + return false; + + if (p->numa_faults[src_nid] > p->numa_faults[dst_nid]) return true; return false; } +#else + +static inline bool migrate_improves_locality(struct task_struct *p, struct lb_env *env) +{ + return false; +} + +static inline bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env) +{ + return false; +} + +#endif /* CONFIG_NUMA_BALANCING */ /* * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? @@ -4055,8 +4093,10 @@ int can_migrate_task(struct task_struct return 1; tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq), env->sd); + if (!tsk_cache_hot) + tsk_cache_hot = migrate_degrades_locality(p, env); if (!tsk_cache_hot || - env->sd->nr_balance_failed > env->sd->cache_nice_tries) { + env->sd->nr_balance_failed > env->sd->cache_nice_tries) { if (tsk_cache_hot) { schedstat_inc(env->sd, lb_hot_gained[env->idle]);