From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx193.postini.com [74.125.245.193]) by kanga.kvack.org (Postfix) with SMTP id CF6C56B0036 for ; Fri, 28 Jun 2013 05:04:54 -0400 (EDT) Date: Fri, 28 Jun 2013 11:04:47 +0200 From: Peter Zijlstra Subject: Re: [PATCH 5/8] sched: Favour moving tasks towards the preferred node Message-ID: <20130628090447.GD28407@twins.programming.kicks-ass.net> References: <1372257487-9749-1-git-send-email-mgorman@suse.de> <1372257487-9749-6-git-send-email-mgorman@suse.de> <20130628081120.GE17195@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130628081120.GE17195@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Srikar Dronamraju Cc: Mel Gorman , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML On Fri, Jun 28, 2013 at 01:41:20PM +0530, Srikar Dronamraju wrote: Please trim your replies. > > +/* 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 && > > Lets say even if the numa_migrate_seq is greater than settle_count but running > on a wrong node, then shouldnt this be taken as a good opportunity to > move the task? I think that's what its doing; so this stmt says; if seq is large and we're trying to move to the 'right' node; move it noaw. > > + p->numa_preferred_nid == dst_nid) > > + return true; > > + > > + return false; > > +} > > + > > + > > /* > > * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? > > */ > > @@ -3945,10 +3977,14 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env) > > > > /* > > * Aggressive migration if: > > - * 1) task is cache cold, or > > - * 2) too many balance attempts have failed. > > + * 1) destination numa is preferred > > + * 2) task is cache cold, or > > + * 3) too many balance attempts have failed. > > */ > > > > + if (migrate_improves_locality(p, env)) > > + return 1; > > Shouldnt this be under tsk_cache_hot check? > > If the task is cache hot, then we would have to update the corresponding schedstat > metrics. No; you want migrate_degrades_locality() to be like task_hot(). You want to _always_ migrate tasks towards better locality irrespective of local cache hotness. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org