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

From: Miaohe Lin
Date: Wed Feb 10 2021 - 02:14:06 EST


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

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 da347047ea10..4f2c92ddbca4 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5632,6 +5632,12 @@ 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