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mm: fix remote numa hits statistics

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Jia He has noticed that commit b9f00e147f ("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 b9f00e147f already.

Fixes: b9f00e147f ("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 <mhocko@suse.com>
Reported-by: Jia He <hejianet@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz> # with cbmc[1] superpowers
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michal Hocko 2017-01-10 16:57:39 -08:00 committed by Linus Torvalds
parent f931ab479d
commit 2df26639e7
1 changed files with 4 additions and 11 deletions
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15
mm/page_alloc.c
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@ -2583,30 +2583,23 @@ 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
}