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authorRik van Riel <riel@redhat.com>2014-10-09 17:27:47 -0400
committerIngo Molnar <mingo@kernel.org>2014-10-28 10:47:52 +0100
commit9de05d48711cd5314920ed05f873d84eaf66ccf1 (patch)
treebd03884dd93b59f151b78c674f444354fb46a918
parent54009416ac3b5f219c0df68559ce534287ae97b1 (diff)
sched/numa: Check all nodes when placing a pseudo-interleaved group
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 swapping location with tasks from other NUMA groups. This can keep NUMA groups from converging. Examining all nodes, when dealing with a task in a pseudo-interleaved NUMA group, avoids this problem. Note that only CPUs in nodes that improve the task or group score are examined, so the loop isn't too bad. Tested-by: Vinod Chegu <chegu_vinod@hp.com> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: "Vinod Chegu" <chegu_vinod@hp.com> Cc: mgorman@suse.de Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20141009172747.0d97c38c@annuminas.surriel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/sched/fair.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7760c2ad3162..ec32c26d7fb6 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1436,8 +1436,15 @@ 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;

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