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

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

Link: https://lkml.kernel.org/r/20210308112809.26107-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 87104dc..c3d47af 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5682,6 +5682,12 @@ 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]--;