From 9682468747390c14962114f261cd76ba188ed987 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Wed, 3 Jun 2020 16:02:46 -0700 Subject: [PATCH] mm: remove use-once cache bias from LRU balancing When the splitlru patches divided page cache and swap-backed pages into separate LRU lists, the pressure balance between the lists was biased to account for the fact that streaming IO can cause memory pressure with a flood of pages that are used only once. New page cache additions would tip the balance toward the file LRU, and repeat access would neutralize that bias again. This ensured that page reclaim would always go for used-once cache first. Since e9868505987a ("mm,vmscan: only evict file pages when we have plenty"), page reclaim generally skips over swap-backed memory entirely as long as there is used-once cache present, and will apply the LRU balancing when only repeatedly accessed cache pages are left - at which point the previous use-once bias will have been neutralized. This makes the use-once cache balancing bias unnecessary. Signed-off-by: Johannes Weiner Signed-off-by: Andrew Morton Acked-by: Michal Hocko Acked-by: Minchan Kim Cc: Joonsoo Kim Cc: Rik van Riel Link: http://lkml.kernel.org/r/20200520232525.798933-7-hannes@cmpxchg.org Signed-off-by: Linus Torvalds --- mm/swap.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/mm/swap.c b/mm/swap.c index 6196d79..116b609 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -293,7 +293,6 @@ static void __activate_page(struct page *page, struct lruvec *lruvec, void *arg) { if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { - int file = page_is_file_lru(page); int lru = page_lru_base_type(page); del_page_from_lru_list(page, lruvec, lru); @@ -303,7 +302,6 @@ static void __activate_page(struct page *page, struct lruvec *lruvec, trace_mm_lru_activate(page); __count_vm_event(PGACTIVATE); - update_page_reclaim_stat(lruvec, file, 1, hpage_nr_pages(page)); } } @@ -975,9 +973,6 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec, if (page_evictable(page)) { lru = page_lru(page); - update_page_reclaim_stat(lruvec, is_file_lru(lru), - PageActive(page), - hpage_nr_pages(page)); if (was_unevictable) count_vm_event(UNEVICTABLE_PGRESCUED); } else { -- 2.7.4