From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753450AbaJQHaP (ORCPT ); Fri, 17 Oct 2014 03:30:15 -0400 Received: from shelob.surriel.com ([74.92.59.67]:35990 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753337AbaJQHaG (ORCPT ); Fri, 17 Oct 2014 03:30:06 -0400 From: riel@redhat.com To: linux-kernel@vger.kernel.org Cc: chegu_vinod@hp.com, peterz@infradead.org, mingo@redhat.com, mgorman@suse.de Subject: [PATCH 6/6] sched,numa: check all nodes when placing a pseudo-interleaved group Date: Fri, 17 Oct 2014 03:29:54 -0400 Message-Id: <1413530994-9732-7-git-send-email-riel@redhat.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1413530994-9732-1-git-send-email-riel@redhat.com> References: <1413530994-9732-1-git-send-email-riel@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rik van Riel In pseudo-interleaved numa_groups, all tasks try to relocate to the group's preferred_nid. When a group is spread across multiple NUMA nodes, this can lead to tasks swapping their location with other tasks inside the same group, instead of having the group converge on a few nodes. When placing a task in a pseudo-interleaved numa_group, it pays to examine all nodes, to see if it isn't better to move to eg. the #2 node, so the group locality can be improved. Signed-off-by: Rik van Riel Tested-by: Chegu Vinod --- kernel/sched/fair.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b973d77..00c1137 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1425,8 +1425,15 @@ static int task_numa_migrate(struct task_struct *p) /* Try to find a spot on the preferred nid. */ task_numa_find_cpu(&env, taskimp, groupimp); - /* No space available on the preferred nid. Look elsewhere. */ - if (env.best_cpu == -1) { + /* + * Look at other nodes in these cases: + * - there is no space available on the preferred_nid + * - the task is part of a numa_group that is interleaved across + * multiple NUMA nodes; in order to better consolidate the group, + * we need to check other locations. + */ + if (env.best_cpu == -1 || (p->numa_group && + nodes_weight(p->numa_group->active_nodes) > 1)) { for_each_online_node(nid) { if (nid == env.src_nid || nid == p->numa_preferred_nid) continue; -- 1.9.3