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authorJohannes Weiner <hannes@cmpxchg.org>2013-12-20 14:54:12 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2013-12-20 12:19:18 -0800
commitfff4068cba484e6b0abe334ed6b15d5a215a3b25 (patch)
tree0357c201066f054adc06fb6e274bac1b981debc1
parent8798cee2f90292ca4ca84baccc757e4d06f8797f (diff)
downloadlinux-fff4068cba484e6b0abe334ed6b15d5a215a3b25.tar.gz
mm: page_alloc: revert NUMA aspect of fair allocation policy
Commit 81c0a2bb515f ("mm: page_alloc: fair zone allocator policy") meant to bring aging fairness among zones in system, but it was overzealous and badly regressed basic workloads on NUMA systems. Due to the way kswapd and page allocator interacts, we still want to make sure that all zones in any given node are used equally for all allocations to maximize memory utilization and prevent thrashing on the highest zone in the node. While the same principle applies to NUMA nodes - memory utilization is obviously improved by spreading allocations throughout all nodes - remote references can be costly and so many workloads prefer locality over memory utilization. The original change assumed that zone_reclaim_mode would be a good enough predictor for that, but it turned out to be as indicative as a coin flip. Revert the NUMA aspect of the fairness until we can find a proper way to make it configurable and agree on a sane default. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: <stable@kernel.org> # 3.12 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_alloc.c19
1 files changed, 9 insertions, 10 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 580a5f075ed0..5248fe070aa4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1816,7 +1816,7 @@ static void zlc_clear_zones_full(struct zonelist *zonelist)
static bool zone_local(struct zone *local_zone, struct zone *zone)
{
- return node_distance(local_zone->node, zone->node) == LOCAL_DISTANCE;
+ return local_zone->node == zone->node;
}
static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
@@ -1913,18 +1913,17 @@ zonelist_scan:
* page was allocated in should have no effect on the
* time the page has in memory before being reclaimed.
*
- * When zone_reclaim_mode is enabled, try to stay in
- * local zones in the fastpath. If that fails, the
- * slowpath is entered, which will do another pass
- * starting with the local zones, but ultimately fall
- * back to remote zones that do not partake in the
- * fairness round-robin cycle of this zonelist.
+ * Try to stay in local zones in the fastpath. If
+ * that fails, the slowpath is entered, which will do
+ * another pass starting with the local zones, but
+ * ultimately fall back to remote zones that do not
+ * partake in the fairness round-robin cycle of this
+ * zonelist.
*/
if (alloc_flags & ALLOC_WMARK_LOW) {
if (zone_page_state(zone, NR_ALLOC_BATCH) <= 0)
continue;
- if (zone_reclaim_mode &&
- !zone_local(preferred_zone, zone))
+ if (!zone_local(preferred_zone, zone))
continue;
}
/*
@@ -2390,7 +2389,7 @@ static void prepare_slowpath(gfp_t gfp_mask, unsigned int order,
* thrash fairness information for zones that are not
* actually part of this zonelist's round-robin cycle.
*/
- if (zone_reclaim_mode && !zone_local(preferred_zone, zone))
+ if (!zone_local(preferred_zone, zone))
continue;
mod_zone_page_state(zone, NR_ALLOC_BATCH,
high_wmark_pages(zone) -