Messages in this thread Patch in this message | | | Date | Mon, 16 Dec 2013 15:25:07 -0500 | From | Johannes Weiner <> | Subject | Re: [PATCH 3/7] mm: page_alloc: Use zone node IDs to approximate locality |
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On Fri, Dec 13, 2013 at 02:10:03PM +0000, Mel Gorman wrote: > zone_local is using node_distance which is a more expensive call than > necessary. On x86, it's another function call in the allocator fast path > and increases cache footprint. This patch makes the assumption zones on a > local node will share the same node ID. The necessary information should > already be cache hot. > > Signed-off-by: Mel Gorman <mgorman@suse.de> > --- > mm/page_alloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 64020eb..fd9677e 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 zone_to_nid(zone) == numa_node_id();
Why numa_node_id()? We pass in the preferred zone as @local_zone:
return zone_to_nid(local_zone) == zone_to_nid(zone)
Or even just compare the ->zone_pgdat pointers?
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