linux-kernel - [PATCH v2 2/5] maple_tree: Avoid ascending when mas->min is also the parent's minimum

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Message-Id: <20231120070937.35481-3-zhangpeng.00@bytedance.com>
Date:   Mon, 20 Nov 2023 15:09:34 +0800
From:   Peng Zhang <zhangpeng.00@...edance.com>
To:     Liam.Howlett@...cle.com, dan.carpenter@...aro.org,
        akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        maple-tree@...ts.infradead.org,
        Peng Zhang <zhangpeng.00@...edance.com>
Subject: [PATCH v2 2/5] maple_tree: Avoid ascending when mas->min is also the parent's minimum

When the child node is the first child of its parent node, mas->min does
not need to be updated. This can reduce the number of ascending times
in some cases.

Signed-off-by: Peng Zhang <zhangpeng.00@...edance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 lib/maple_tree.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 067b186202d7..cc928b5f753d 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1088,14 +1088,16 @@ static int mas_ascend(struct ma_state *mas)
 		return 0;
 	}
 
-	if (!mas->min)
+	min = 0;
+	max = ULONG_MAX;
+	if (!mas->offset) {
+		min = mas->min;
 		set_min = true;
+	}
 
 	if (mas->max == ULONG_MAX)
 		set_max = true;
 
-	min = 0;
-	max = ULONG_MAX;
 	do {
 		p_enode = a_enode;
 		a_type = mas_parent_type(mas, p_enode);
-- 
2.20.1