[PATCH 1/7] sched,numa: use group's max nid as task's preferred nid

From: riel
Date: Mon Jun 23 2014 - 11:44:11 EST


From: Rik van Riel <riel@xxxxxxxxxx>

>From task_numa_placement, always try to consolidate the tasks
in a group on the group's top nid.

In case this task is part of a group that is interleaved over
multiple nodes, task_numa_migrate will set the task's preferred
nid to the best node it could find for the task, so this patch
will cause at most one run through task_numa_migrate.

Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
---
kernel/sched/fair.c | 17 +----------------
1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1f9c457..4a58e79 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1594,23 +1594,8 @@ static void task_numa_placement(struct task_struct *p)

if (p->numa_group) {
update_numa_active_node_mask(p->numa_group);
- /*
- * If the preferred task and group nids are different,
- * iterate over the nodes again to find the best place.
- */
- if (max_nid != max_group_nid) {
- unsigned long weight, max_weight = 0;
-
- for_each_online_node(nid) {
- weight = task_weight(p, nid) + group_weight(p, nid);
- if (weight > max_weight) {
- max_weight = weight;
- max_nid = nid;
- }
- }
- }
-
spin_unlock_irq(group_lock);
+ max_nid = max_group_nid;
}

if (max_faults) {
--
1.8.5.3

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