[PATCH -V8 07/10] mm/vmscan: add helper for querying ability to age anonymous pages
From: Huang Ying <hidden>
Date: 2021-06-18 06:20:50
Also in:
lkml
Subsystem:
memory management, memory management - mglru (multi-gen lru), memory management - reclaim, the rest · Maintainers:
Andrew Morton, Johannes Weiner, Linus Torvalds
From: Dave Hansen <dave.hansen@linux.intel.com> Anonymous pages are kept on their own LRU(s). These lists could theoretically always be scanned and maintained. But, without swap, there is currently nothing the kernel can *do* with the results of a scanned, sorted LRU for anonymous pages. A check for '!total_swap_pages' currently serves as a valid check as to whether anonymous LRUs should be maintained. However, another method will be added shortly: page demotion. Abstract out the 'total_swap_pages' checks into a helper, give it a logically significant name, and check for the possibility of page demotion. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: "Huang, Ying" <redacted> Reviewed-by: Yang Shi <redacted> Reviewed-by: Greg Thelen <redacted> Cc: Michal Hocko <mhocko@suse.com> Cc: Wei Xu <weixugc@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Dan Williams <redacted> Cc: David Hildenbrand <redacted> Cc: osalvador <osalvador@suse.de> --- mm/vmscan.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7d5c7216a4b7..8654cec65522 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c@@ -2706,6 +2706,26 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, } } +/* + * Anonymous LRU management is a waste if there is + * ultimately no way to reclaim the memory. + */ +bool anon_should_be_aged(struct lruvec *lruvec) +{ + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + + /* Aging the anon LRU is valuable if swap is present: */ + if (total_swap_pages > 0) + return true; + + /* Also valuable if anon pages can be demoted: */ + if (next_demotion_node(pgdat->node_id) >= 0) + return true; + + /* No way to reclaim anon pages. Should not age anon LRUs: */ + return false; +} + static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) { unsigned long nr[NR_LRU_LISTS];
@@ -2815,7 +2835,8 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) * Even if we did not try to evict anon pages at all, we want to * rebalance the anon lru active/inactive ratio. */ - if (total_swap_pages && inactive_is_low(lruvec, LRU_INACTIVE_ANON)) + if (anon_should_be_aged(lruvec) && + inactive_is_low(lruvec, LRU_INACTIVE_ANON)) shrink_active_list(SWAP_CLUSTER_MAX, lruvec, sc, LRU_ACTIVE_ANON); }
@@ -3644,10 +3665,11 @@ static void age_active_anon(struct pglist_data *pgdat, struct mem_cgroup *memcg; struct lruvec *lruvec; - if (!total_swap_pages) + lruvec = mem_cgroup_lruvec(NULL, pgdat); + + if (!anon_should_be_aged(lruvec)) return; - lruvec = mem_cgroup_lruvec(NULL, pgdat); if (!inactive_is_low(lruvec, LRU_INACTIVE_ANON)) return;
--
2.30.2