For reclamation, it makes sense to reclaim folios from tail to head, as folios near the head are relatively hot. However, when moving folios from the oldest generation to the second-oldest generation, using the tail-to-head order would effectively cause a cold/hot inversion. Signed-off-by: Barry Song (Xiaomi) Reviewed-by: Baoquan He Tested-by: Xueyuan Chen Reviewed-by: Lian Wang --- mm/vmscan.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 1907a946840d..76dfa9575852 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -192,11 +192,27 @@ static inline void prefetchw_prev_lru_folio(struct folio *folio, prefetchw(&prev->flags); } } + +static inline void prefetchw_next_lru_folio(struct folio *folio, + struct list_head *base) +{ + if (folio->lru.next != base) { + struct folio *next; + + next = list_entry(folio->lru.next, struct folio, lru); + prefetchw(&next->flags); + } +} #else static inline void prefetchw_prev_lru_folio(struct folio *folio, struct list_head *base) { } + +static inline void prefetchw_next_lru_folio(struct folio *folio, + struct list_head *base) +{ +} #endif /* @@ -3938,10 +3954,11 @@ static bool inc_min_seq(struct lruvec *lruvec, int type, int swappiness) /* prevent cold/hot inversion if the type is evictable */ for (zone = 0; zone < MAX_NR_ZONES; zone++) { struct list_head *head = &lrugen->folios[old_gen][type][zone]; + struct list_head *pos = head->next; long delta = 0; - while (!list_empty(head)) { - struct folio *folio = lru_to_folio(head); + while (pos != head) { + struct folio *folio = list_entry(pos, struct folio, lru); long nr_pages = folio_nr_pages(folio); int refs = folio_lru_refs(folio); bool workingset = folio_test_workingset(folio); @@ -3952,6 +3969,8 @@ static bool inc_min_seq(struct lruvec *lruvec, int type, int swappiness) VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio); VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio); + prefetchw_next_lru_folio(folio, head); + pos = pos->next; new_gen = __folio_inc_gen(folio, old_gen, &gen_increased); /* * If gen_increased is false, this is a promotion. Put folios -- 2.34.1