2017-03-01 07:56:17

by Johannes Weiner

Subject: [PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling

PF_MEMALLOC direct reclaimers get throttled on a node when the sum of
all free pages in each zone fall below half the min watermark. During
the summation, we want to exclude zones that don't have reclaimables.
Checking the same pgdat over and over again doesn't make sense.

Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node")
Signed-off-by: Johannes Weiner <[email protected]>
---
mm/vmscan.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 407b27831ff7..f006140f58c6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2838,8 +2838,10 @@ static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)

for (i = 0; i <= ZONE_NORMAL; i++) {
zone = &pgdat->node_zones[i];
- if (!managed_zone(zone) ||
- pgdat_reclaimable_pages(pgdat) == 0)
+ if (!managed_zone(zone))
+ continue;
+
+ if (!zone_reclaimable_pages(zone))
continue;

pfmemalloc_reserve += min_wmark_pages(zone);
--
2.11.1

2017-03-01 15:04:07

by Michal Hocko

Subject: Re: [PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling

On Tue 28-02-17 16:40:00, Johannes Weiner wrote:
> PF_MEMALLOC direct reclaimers get throttled on a node when the sum of
> all free pages in each zone fall below half the min watermark. During
> the summation, we want to exclude zones that don't have reclaimables.
> Checking the same pgdat over and over again doesn't make sense.
>
> Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node")
> Signed-off-by: Johannes Weiner <[email protected]>

Acked-by: Michal Hocko <[email protected]>

> ---
> mm/vmscan.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 407b27831ff7..f006140f58c6 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2838,8 +2838,10 @@ static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)
>
> for (i = 0; i <= ZONE_NORMAL; i++) {
> zone = &pgdat->node_zones[i];
> - if (!managed_zone(zone) ||
> - pgdat_reclaimable_pages(pgdat) == 0)
> + if (!managed_zone(zone))
> + continue;
> +
> + if (!zone_reclaimable_pages(zone))
> continue;
>
> pfmemalloc_reserve += min_wmark_pages(zone);
> --
> 2.11.1

--
Michal Hocko
SUSE Labs

2017-03-02 03:26:01

by Hillf Danton

Subject: Re: [PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling

On March 01, 2017 5:40 AM Johannes Weiner wrote:
>
> PF_MEMALLOC direct reclaimers get throttled on a node when the sum of
> all free pages in each zone fall below half the min watermark. During
> the summation, we want to exclude zones that don't have reclaimables.
> Checking the same pgdat over and over again doesn't make sense.
>
> Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node")
> Signed-off-by: Johannes Weiner <[email protected]>
> ---
Acked-by: Hillf Danton <[email protected]>