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

Message ID 20210210071251.44084-1-linmiaohe@huawei.com
State Accepted
Commit 5af1ab1d24e0842e2ca72c1fd0833864f6fa458a
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Series
  • mm/hugetlb: optimize the surplus state transfer code in move_hugetlb_state()
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Commit Message

Miaohe Lin Feb. 10, 2021, 7:12 a.m. UTC
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@huawei.com>
---
 mm/hugetlb.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Mike Kravetz Feb. 13, 2021, 12:51 a.m. UTC | #1
On 2/9/21 11:12 PM, Miaohe Lin wrote:
> 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@huawei.com>
> ---
>  mm/hugetlb.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Thanks,

I was going to comment that the usual case is migrating to another node
and old_nid != new_nid.  However, this really is workload and system
configuration dependent.  In any case, the quick check is worth potentially
saving a lock/unlock cycle.

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

Patch
diff mbox series

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]--;