[PATCH 2/5] mm/hugetlb: optimize the surplus state transfer code in move_hugetlb_state()

[Miaohe Lin]

We should not transfer the per-node surplus state when we do not cross the
node in order to save some cpu cycles

Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
 mm/hugetlb.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 33a3edf79022..695603071f2c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5621,6 +5621,12 @@ void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason)
 		SetHPageTemporary(oldpage);
 		ClearHPageTemporary(newpage);
 
+		/*
+		 * There is no need to transfer the per-node surplus state
+		 * when we do not cross the node.
+		 */
+		if (new_nid == old_nid)
+			return;
 		spin_lock(&hugetlb_lock);
 		if (h->surplus_huge_pages_node[old_nid]) {
 			h->surplus_huge_pages_node[old_nid]--;
-- 
2.19.1