mm, vmscan: only wakeup kswapd once per node for the requested classzone
kswapd is woken when zones are below the low watermark but the wakeup
decision is not taking the classzone into account. Now that reclaim is
node-based, it is only required to wake kswapd once per node and only if
all zones are unbalanced for the requested classzone.
Note that one node might be checked multiple times if the zonelist is
ordered by node because there is no cheap way of tracking what nodes
have already been visited. For zone-ordering, each node should be
checked only once.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Hillf Danton <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Rik van Riel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0f92e04..a34d9fc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3367,10 +3367,14 @@
{
struct zoneref *z;
struct zone *zone;
+ pg_data_t *last_pgdat = NULL;
for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
- ac->high_zoneidx, ac->nodemask)
- wakeup_kswapd(zone, order, ac_classzone_idx(ac));
+ ac->high_zoneidx, ac->nodemask) {
+ if (last_pgdat != zone->zone_pgdat)
+ wakeup_kswapd(zone, order, ac_classzone_idx(ac));
+ last_pgdat = zone->zone_pgdat;
+ }
}
static inline unsigned int
