linux-kernel - [PATCH 04/12] mm/swap: skip scanning cluster range if it's empty cluster

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Message-ID: <20250205092721.9395-5-bhe@redhat.com>
Date: Wed,  5 Feb 2025 17:27:13 +0800
From: Baoquan He <bhe@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	akpm@...ux-foundation.org,
	ryncsn@...il.com,
	chrisl@...nel.org,
	Baoquan He <bhe@...hat.com>
Subject: [PATCH 04/12] mm/swap: skip scanning cluster range if it's empty cluster

Since ci->lock has been taken when isolating cluster from
si->free_clusters or taking si->percpu_cluster->next[order],
it's unnecessary to scan and check the cluster range availability
if i'ts empty cluster, and this can accelerate the huge page
swapping.

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 mm/swapfile.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 9c9a4ec6d4c6..61efde853eea 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -729,6 +729,9 @@ static bool cluster_scan_range(struct swap_info_struct *si,
 	unsigned long offset, end = start + nr_pages;
 	unsigned char *map = si->swap_map;
 
+	if (cluster_is_empty(ci))
+		return true;
+
 	for (offset = start; offset < end; offset++) {
 		switch (READ_ONCE(map[offset])) {
 		case 0:
-- 
2.41.0