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mm/vmscan: add pgrotate_anon and pgrotate_file vmstat counters

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Reclaim can spend substantial work on an LRU type without immediately
reclaiming or demoting a corresponding amount of memory.  Record this work
in PGROTATE_ANON and PGROTATE_FILE.

For classic LRU reclaim:

  - Inactive-list reclaim adds nr_scanned - nr_reclaimed to the
    corresponding anon/file counter when isolation succeeds.
  - Active-list reclaim adds referenced executable file folios that
    are retained on the active list to PGROTATE_FILE. Active anon
    reclaim does not contribute this component.

For MGLRU, add the number of initially isolated pages that remain
unreclaimed after both the initial and retry passes to the counter for the
selected anon/file type.

These counters are distinct from the existing pgrotated vm event. 
pgrotated records an actual move to the inactive-list tail, primarily
after reclaim-marked writeback completes or failed invalidation leaves a
folio for accelerated reclaim.  PGROTATE_ANON and PGROTATE_FILE measure
reclaim cost and do not imply that a folio moved to an LRU tail.

A subsequent patch will consume these counters for anon/file scan
balancing.

Link: https://lore.kernel.org/20260727162550.2032-3-usama.arif@linux.dev
Signed-off-by: Usama Arif <usama.arif@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Usama Arif 2026-07-27 09:23:24 -07:00 committed by Andrew Morton
parent a69797fb36
commit 1b089def0f
4 changed files with 19 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/mmzone.h
View File

@ -323,6 +323,8 @@ enum node_stat_item {
PGSCAN_PROACTIVE,
PGSCAN_ANON,
PGSCAN_FILE,
PGROTATE_ANON,
PGROTATE_FILE,
PGREFILL,
#ifdef CONFIG_HUGETLB_PAGE
NR_HUGETLB,

2
mm/memcontrol.c
View File

@ -425,6 +425,8 @@ static const unsigned int memcg_node_stat_items[] = {
PGSCAN_PROACTIVE,
PGSCAN_ANON,
PGSCAN_FILE,
PGROTATE_ANON,
PGROTATE_FILE,
PGREFILL,
#ifdef CONFIG_HUGETLB_PAGE
NR_HUGETLB,

14
mm/vmscan.c
View File

@ -2038,6 +2038,9 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
item = PGSTEAL_KSWAPD + reclaimer_offset(sc);
mod_lruvec_state(lruvec, item, nr_reclaimed);
mod_lruvec_state(lruvec, PGSTEAL_ANON + file, nr_reclaimed);
if (nr_scanned > nr_reclaimed)
mod_lruvec_state(lruvec, PGROTATE_ANON + file,
nr_scanned - nr_reclaimed);
lruvec_lock_irq(lruvec);
lru_note_cost_unlock_irq(lruvec, file, stat.nr_pageout,
@ -2147,6 +2150,8 @@ static void shrink_active_list(unsigned long nr_to_scan,
count_vm_events(PGDEACTIVATE, nr_deactivate);
count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);
mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
if (nr_rotated)
mod_lruvec_state(lruvec, PGROTATE_ANON + file, nr_rotated);
lruvec_lock_irq(lruvec);
lru_note_cost_unlock_irq(lruvec, file, 0, nr_rotated);
@ -4828,7 +4833,8 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
struct reclaim_stat stat;
struct lru_gen_mm_walk *walk;
int scanned, reclaimed;
int isolated = 0, type, type_scanned;
int isolated = 0, nr_isolated = 0, type, type_scanned;
unsigned long total_reclaimed = 0;
bool skip_retry = false;
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
@ -4840,6 +4846,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
scanned = isolate_folios(nr_to_scan, lruvec, sc, swappiness,
&list, &isolated, &type, &type_scanned);
nr_isolated = isolated;
/* Scanning may have emptied the oldest gen, flush it */
if (scanned)
@ -4852,6 +4859,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
retry:
reclaimed = shrink_folio_list(&list, pgdat, sc, &stat, false, memcg);
sc->nr_reclaimed += reclaimed;
total_reclaimed += reclaimed;
/* Retry pass is only meant for clean folios without new isolation */
if (isolated)
handle_reclaim_writeback(isolated, pgdat, sc, &stat);
@ -4903,6 +4911,10 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
goto retry;
}
if (nr_isolated > total_reclaimed)
mod_lruvec_state(lruvec, PGROTATE_ANON + type,
nr_isolated - total_reclaimed);
return scanned;
}

2
mm/vmstat.c
View File

@ -1301,6 +1301,8 @@ const char * const vmstat_text[] = {
[I(PGSCAN_PROACTIVE)] = "pgscan_proactive",
[I(PGSCAN_ANON)] = "pgscan_anon",
[I(PGSCAN_FILE)] = "pgscan_file",
[I(PGROTATE_ANON)] = "pgrotate_anon",
[I(PGROTATE_FILE)] = "pgrotate_file",
[I(PGREFILL)] = "pgrefill",
#ifdef CONFIG_HUGETLB_PAGE
[I(NR_HUGETLB)] = "nr_hugetlb",