Re: [patch] mm, vmscan: avoid thrashing anon lru when free + file is low

From: David Rientjes
Date: Wed Apr 19 2017 - 19:25:02 EST


On Wed, 19 Apr 2017, Minchan Kim wrote:

> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 24efcc20af91..5d2f3fa41e92 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2174,8 +2174,17 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
> }
>
> if (unlikely(pgdatfile + pgdatfree <= total_high_wmark)) {
> - scan_balance = SCAN_ANON;
> - goto out;
> + /*
> + * force SCAN_ANON if inactive anonymous LRU lists of
> + * eligible zones are enough pages. Otherwise, thrashing
> + * can be happen on the small anonymous LRU list.
> + */
> + if (!inactive_list_is_low(lruvec, false, NULL, sc, false) &&
> + lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, sc->reclaim_idx)
> + >> sc->priority) {
> + scan_balance = SCAN_ANON;
> + goto out;
> + }
> }
> }
>

Hi Minchan,

This looks good and it correctly biases against SCAN_ANON for my workload
that was thrashing the anon lrus. Feel free to use parts of my changelog
if you'd like.

Tested-by: David Rientjes <rientjes@xxxxxxxxxx>