On Tue 22-10-19 10:47:56, Johannes Weiner wrote:
> This function currently takes the node or lruvec size and subtracts
> the zones that are excluded by the classzone index of the
> allocation. It uses four different types of counters to do this.
>
> Just add up the eligible zones.
The original intention was to optimize this for GFP_KERNEL like
allocations by reducing the number of zones to reduce. But considering
this is not called from hot paths I do agree that a simpler code is more
preferable.
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/vmscan.c | 21 +++++----------------
> 1 file changed, 5 insertions(+), 16 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 1154b3a2b637..57f533b808f2 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -351,32 +351,21 @@ unsigned long zone_reclaimable_pages(struct zone *zone)
> */
> unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx)
> {
> - unsigned long lru_size = 0;
> + unsigned long size = 0;
> int zid;
>
> - if (!mem_cgroup_disabled()) {
> - for (zid = 0; zid < MAX_NR_ZONES; zid++)
> - lru_size += mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
> - } else
> - lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
> -
> - for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
> + for (zid = 0; zid <= zone_idx; zid++) {
> struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid];
> - unsigned long size;
>
> if (!managed_zone(zone))
> continue;
>
> if (!mem_cgroup_disabled())
> - size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
> + size += mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
> else
> - size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid],
> - NR_ZONE_LRU_BASE + lru);
> - lru_size -= min(size, lru_size);
> + size += zone_page_state(zone, NR_ZONE_LRU_BASE + lru);
> }
> -
> - return lru_size;
> -
> + return size;
> }
>
> /*
> --
> 2.23.0
--
Michal Hocko
SUSE Labs
