Messages in this thread Patch in this message | | | From | Huang Ying <> | Subject | [PATCH -V9 6/9] mm/vmscan: add helper for querying ability to age anonymous pages | Date | Fri, 25 Jun 2021 15:32:01 +0800 |
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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" <ying.huang@intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Greg Thelen <gthelen@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Wei Xu <weixugc@google.com> Cc: osalvador <osalvador@suse.de> Cc: Zi Yan <ziy@nvidia.com> Cc: David Rientjes <rientjes@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Hildenbrand <david@redhat.com>
Changes since 20210618: * Rename function per Oscar's comments. * Change parameter per Wei's comments. * Make the function static. * Consider whether demotion is disabled. --- mm/vmscan.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c index 78b3bae71520..55f6192b2a51 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2716,6 +2716,26 @@ 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. + */ +static bool anon_can_be_aged(struct pglist_data *pgdat, + struct scan_control *sc) +{ + /* 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 (!sc->no_demotion && + next_demotion_node(pgdat->node_id) != NUMA_NO_NODE) + 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]; @@ -2825,7 +2845,8 @@ 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_can_be_aged(lruvec_pgdat(lruvec), sc) && + inactive_is_low(lruvec, LRU_INACTIVE_ANON)) shrink_active_list(SWAP_CLUSTER_MAX, lruvec, sc, LRU_ACTIVE_ANON); } @@ -3654,7 +3675,7 @@ static void age_active_anon(struct pglist_data *pgdat, struct mem_cgroup *memcg; struct lruvec *lruvec; - if (!total_swap_pages) + if (!anon_can_be_aged(pgdat, sc)) return; lruvec = mem_cgroup_lruvec(NULL, pgdat); -- 2.30.2
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