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From: Chen Ridong <chenridong@huaweicloud.com>
To: akpm@linux-foundation.org, axelrasmussen@google.com,
	yuanchu@google.com, weixugc@google.com, hannes@cmpxchg.org,
	david@kernel.org, mhocko@kernel.org, zhengqi.arch@bytedance.com,
	shakeel.butt@linux.dev, lorenzo.stoakes@oracle.com,
	yuzhao@google.com, jaewon31.kim@samsung.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	lujialin4@huawei.com, chenridong@huawei.com
Subject: [PATCH -next] mm: vmscan: correct nr_requested tracing in scan_folios
Date: Wed,  3 Dec 2025 09:40:02 +0000	[thread overview]
Message-ID: <20251203094002.1745458-1-chenridong@huaweicloud.com> (raw)

From: Chen Ridong <chenridong@huawei.com>

When enabling vmscan tracing, it is observed that nr_requested is always
4096, which is confusing.

        mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ...
        mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ...
        mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ...
        mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ...
        mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ...
        mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ...
        mm_vmscan_lru_isolate: classzone=3 order=0 nr_requested=4096 ...

This is because it prints MAX_LRU_BATCH, which is meaningless as it's a
constant. To fix this, modify it to print nr_to_scan as isolate_lru_folios
does.

Fixes: 8c2214fc9a47 ("mm: multi-gen LRU: reuse some legacy trace events")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index fddd168a9737..8cfafd50a7a8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4601,7 +4601,7 @@ static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 	count_memcg_events(memcg, item, isolated);
 	count_memcg_events(memcg, PGREFILL, sorted);
 	__count_vm_events(PGSCAN_ANON + type, isolated);
-	trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, MAX_LRU_BATCH,
+	trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
 				scanned, skipped, isolated,
 				type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);
 	if (type == LRU_GEN_FILE)
-- 
2.34.1



             reply	other threads:[~2025-12-03  9:55 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-03  9:40 Chen Ridong [this message]
2025-12-03 11:33 ` David Hildenbrand (Red Hat)
2025-12-04  0:46   ` Chen Ridong
2025-12-04 11:54     ` David Hildenbrand (Red Hat)
2025-12-04 12:19       ` Chen Ridong
2025-12-04  9:05   ` [PATCH -next] mm: vmscan: correct nr_requested tracing in Lance Yang

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