From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx126.postini.com [74.125.245.126]) by kanga.kvack.org (Postfix) with SMTP id 70EB76B0032 for ; Thu, 11 Jul 2013 08:31:32 -0400 (EDT) Date: Thu, 11 Jul 2013 14:30:38 +0200 From: Peter Zijlstra Subject: Re: [PATCH 08/16] sched: Reschedule task on preferred NUMA node once selected Message-ID: <20130711123038.GH25631@dyad.programming.kicks-ass.net> References: <1373536020-2799-1-git-send-email-mgorman@suse.de> <1373536020-2799-9-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1373536020-2799-9-git-send-email-mgorman@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML On Thu, Jul 11, 2013 at 10:46:52AM +0100, Mel Gorman wrote: > @@ -829,10 +854,29 @@ static void task_numa_placement(struct task_struct *p) > } > } > > - /* Update the tasks preferred node if necessary */ > + /* > + * Record the preferred node as the node with the most faults, > + * requeue the task to be running on the idlest CPU on the > + * preferred node and reset the scanning rate to recheck > + * the working set placement. > + */ > if (max_faults && max_nid != p->numa_preferred_nid) { > + int preferred_cpu; > + > + /* > + * If the task is not on the preferred node then find the most > + * idle CPU to migrate to. > + */ > + preferred_cpu = task_cpu(p); > + if (cpu_to_node(preferred_cpu) != max_nid) { > + preferred_cpu = find_idlest_cpu_node(preferred_cpu, > + max_nid); > + } > + > + /* Update the preferred nid and migrate task if possible */ > p->numa_preferred_nid = max_nid; > p->numa_migrate_seq = 0; > + migrate_task_to(p, preferred_cpu); > } > } Now what happens if the migrations fails? We set numa_preferred_nid to max_nid but then never re-try the migration. Should we not re-try the migration every so often, regardless of whether max_nid changed? -- 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