From 14a4dfaadb2529002298944b371c1c6c80b7fd39 Mon Sep 17 00:00:00 2001 From: Jia He Date: Fri, 17 Feb 2017 01:52:15 -0500 Subject: [PATCH 1/2] mm: fix remote numa hits statistics Jia He has noticed that commit b9f00e147f27 ("mm, page_alloc: reduce branches in zone_statistics") has an unintentional side effect that remote node allocation requests are accounted as NUMA_MISS rathat than NUMA_HIT and NUMA_OTHER if such a request doesn't use __GFP_OTHER_NODE. There are many of these potentially because the flag is used very rarely while we have many users of __alloc_pages_node. Fix this by simply ignoring __GFP_OTHER_NODE (it can be removed in a follow up patch) and treat all allocations that were satisfied from the preferred zone's node as NUMA_HITS because this is the same node we requested the allocation from in most cases. If this is not the local node then we just account it as NUMA_OTHER rather than NUMA_LOCAL. One downsize would be that an allocation request for a node which is outside of the mempolicy nodemask would be reported as a hit which is a bit weird but that was the case before b9f00e147f27 already. Fixes: b9f00e147f27 ("mm, page_alloc: reduce branches in zone_statistics") Link: http://lkml.kernel.org/r/20170102153057.9451-2-mhocko@kernel.org Signed-off-by: Michal Hocko Reported-by: Jia He Reviewed-by: Vlastimil Babka # with cbmc[1] superpowers Acked-by: Mel Gorman Cc: Johannes Weiner Cc: Joonsoo Kim Cc: Taku Izumi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Jia He --- mm/page_alloc.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 212a017..0a9bda6 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2532,30 +2532,23 @@ int __isolate_free_page(struct page *page, unsigned int order) * Update NUMA hit/miss statistics * * Must be called with interrupts disabled. - * - * When __GFP_OTHER_NODE is set assume the node of the preferred - * zone is the local node. This is useful for daemons who allocate - * memory on behalf of other processes. */ static inline void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags) { #ifdef CONFIG_NUMA - int local_nid = numa_node_id(); enum zone_stat_item local_stat = NUMA_LOCAL; - if (unlikely(flags & __GFP_OTHER_NODE)) { + if (z->node != numa_node_id()) local_stat = NUMA_OTHER; - local_nid = preferred_zone->node; - } - if (z->node == local_nid) { + if (z->node == preferred_zone->node) __inc_zone_state(z, NUMA_HIT); - __inc_zone_state(z, local_stat); - } else { + else { __inc_zone_state(z, NUMA_MISS); __inc_zone_state(preferred_zone, NUMA_FOREIGN); } + __inc_zone_state(z, local_stat); #endif } -- 2.7.4