[PATCH 2/2] mm: page_alloc: Do not cache reclaim distances

From: Mel Gorman
Date: Tue Apr 08 2014 - 04:24:37 EST


pgdat->reclaim_nodes tracks if a remote node is allowed to be reclaimed by
zone_reclaim due to its distance. As it is expected that zone_reclaim_mode
will be rarely enabled it is unreasonable for all machines to take a penalty.
Fortunately, the zone_reclaim_mode() path is already slow and it is the path
that takes the hit.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 1 -
mm/page_alloc.c | 15 +--------------
2 files changed, 1 insertion(+), 15 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 9b61b9b..564b169 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -757,7 +757,6 @@ typedef struct pglist_data {
unsigned long node_spanned_pages; /* total size of physical page
range, including holes */
int node_id;
- nodemask_t reclaim_nodes; /* Nodes allowed to reclaim from */
wait_queue_head_t kswapd_wait;
wait_queue_head_t pfmemalloc_wait;
struct task_struct *kswapd; /* Protected by lock_memory_hotplug() */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a256f85..574928e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1863,16 +1863,7 @@ static bool zone_local(struct zone *local_zone, struct zone *zone)

static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
{
- return node_isset(local_zone->node, zone->zone_pgdat->reclaim_nodes);
-}
-
-static void __paginginit init_zone_allows_reclaim(int nid)
-{
- int i;
-
- for_each_online_node(i)
- if (node_distance(nid, i) <= RECLAIM_DISTANCE)
- node_set(i, NODE_DATA(nid)->reclaim_nodes);
+ return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) < RECLAIM_DISTANCE;
}

#else /* CONFIG_NUMA */
@@ -1906,9 +1897,6 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
return true;
}

-static inline void init_zone_allows_reclaim(int nid)
-{
-}
#endif /* CONFIG_NUMA */

/*
@@ -4917,7 +4905,6 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size,

pgdat->node_id = nid;
pgdat->node_start_pfn = node_start_pfn;
- init_zone_allows_reclaim(nid);
#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
#endif
--
1.8.4.5

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