Commit 49d921b4 authored by Chen Ridong's avatar Chen Ridong Committed by Andrew Morton
Browse files

mm: vmscan: correct nr_requested tracing in scan_folios 

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 capped valued.

Link: https://lkml.kernel.org/r/20251204122355.1822919-1-chenridong@huaweicloud.com


Fixes: 8c2214fc ("mm: multi-gen LRU: reuse some legacy trace events")
Signed-off-by: default avatarChen Ridong <chenridong@huawei.com>
Acked-by: default avatarDavid Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: default avatarLance Yang <lance.yang@linux.dev>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Jaewon Kim <jaewon31.kim@samsung.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Lu Jialin <lujialin4@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 12c1fa8d

mm/vmscan.c

+3 −2
Original line number Diff line number Diff line
@@ -4541,7 +4541,8 @@ static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec, 
	int scanned = 0;

	int isolated = 0;

	int skipped = 0;

	int remaining = min(nr_to_scan, MAX_LRU_BATCH);

	int scan_batch = min(nr_to_scan, MAX_LRU_BATCH);

	int remaining = scan_batch;

	struct lru_gen_folio *lrugen = &lruvec->lrugen;

	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
@@ -4601,7 +4602,7 @@ 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, scan_batch,

				scanned, skipped, isolated,

				type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);

	if (type == LRU_GEN_FILE)