On Sat, 30 Apr 2022 10:10:32 +0900 Wonhyuk Yang <vvghjk1234@xxxxxxxxx> wrote:
> To spread dirty page, nodes are checked whether
> it reached the dirty limit using the expensive
> node_dirty_ok(). To reduce the number of calling
> node_dirty_ok(), last node that hit the dirty
> limit is cached.
>
> Instead of caching the node, caching both node
> and it's result of node_dirty_ok() can reduce
> the number of calling node_dirty_ok() more than
> before.
>
> ...
>
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4068,7 +4068,8 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
> {
> struct zoneref *z;
> struct zone *zone;
> - struct pglist_data *last_pgdat_dirty_limit = NULL;
> + struct pglist_data *last_pgdat = NULL;
> + bool last_pgdat_dirty_limit = false;
> bool no_fallback;
>
> retry:
> @@ -4107,13 +4108,13 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
> * dirty-throttling and the flusher threads.
> */
> if (ac->spread_dirty_pages) {
> - if (last_pgdat_dirty_limit == zone->zone_pgdat)
> - continue;
> + if (last_pgdat != zone->zone_pgdat) {
> + last_pgdat = zone->zone_pgdat;
> + last_pgdat_dirty_limit = node_dirty_ok(zone->zone_pgdat);
> + }
>
> - if (!node_dirty_ok(zone->zone_pgdat)) {
> - last_pgdat_dirty_limit = zone->zone_pgdat;
> + if (!last_pgdat_dirty_limit)
> continue;
> - }
> }
>
> if (no_fallback && nr_online_nodes > 1 &&
Looks reasonable to me. Hopefully Mel and Johannes can review.
I think last_pgdat_dirty_limit isn't a great name. It records the
dirty_ok state of last_pgdat. So why not call it last_pgdat_dirty_ok?
--- a/mm/page_alloc.c~mm-page_alloc-cache-the-result-of-node_dirty_ok-fix
+++ a/mm/page_alloc.c
@@ -4022,7 +4022,7 @@ get_page_from_freelist(gfp_t gfp_mask, u
struct zoneref *z;
struct zone *zone;
struct pglist_data *last_pgdat = NULL;
- bool last_pgdat_dirty_limit = false;
+ bool last_pgdat_dirty_ok = false;
bool no_fallback;
retry:
@@ -4063,10 +4063,10 @@ retry:
if (ac->spread_dirty_pages) {
if (last_pgdat != zone->zone_pgdat) {
last_pgdat = zone->zone_pgdat;
- last_pgdat_dirty_limit = node_dirty_ok(zone->zone_pgdat);
+ last_pgdat_dirty_ok = node_dirty_ok(zone->zone_pgdat);
}
- if (!last_pgdat_dirty_limit)
+ if (!last_pgdat_dirty_ok)
continue;
}
_
