Re: [PATCH 4/9] mm: remove unnecessary reclaimability check from NUMA balancing target

From: Michal Hocko
Date: Wed Mar 01 2017 - 14:25:14 EST


On Tue 28-02-17 16:40:02, Johannes Weiner wrote:
> NUMA balancing already checks the watermarks of the target node to
> decide whether it's a suitable balancing target. Whether the node is
> reclaimable or not is irrelevant when we don't intend to reclaim.

I guess the original intention was to skip nodes which are under strong
memory pressure but I agree that this is questionable heuristic.

> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

> ---
> mm/migrate.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 2c63ac06791b..45a18be27b1a 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1718,9 +1718,6 @@ static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
> {
> int z;
>
> - if (!pgdat_reclaimable(pgdat))
> - return false;
> -
> for (z = pgdat->nr_zones - 1; z >= 0; z--) {
> struct zone *zone = pgdat->node_zones + z;
>
> --
> 2.11.1

--
Michal Hocko
SUSE Labs