On 05/13/2015 04:10 AM, Mel Gorman wrote: > NUMA balancing is meant to be disabled by default on UMA machines but > the check is using nr_node_ids (highest node) instead of num_online_nodes > (online nodes). The consequences are that a UMA machine with a node ID of 1 > or higher will enable NUMA balancing. This will incur useless overhead due > to minor faults with the impact depending on the workload. These are the > impact on the stats when running a kernel build on a single node machine > whose node ID happened to be 1; > > vanilla patched > NUMA base PTE updates 5113158 0 > NUMA huge PMD updates 643 0 > NUMA page range updates 5442374 0 > NUMA hint faults 2109622 0 > NUMA hint local faults 2109622 0 > NUMA hint local percent 100 100 > NUMA pages migrated 0 0 > > Signed-off-by: Mel Gorman <mgorman@xxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> #v3.8+ Reviewed-by: Rik van Riel <riel@xxxxxxxxxx> -- All rights reversed -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>