On Tue, 8 Apr 2014, Vlastimil Babka wrote: > On 04/08/2014 12:34 AM, Mel Gorman wrote: > > When it was introduced, zone_reclaim_mode made sense as NUMA distances > > punished and workloads were generally partitioned to fit into a NUMA > > node. NUMA machines are now common but few of the workloads are NUMA-aware > > and it's routine to see major performance due to zone_reclaim_mode being > > disabled but relatively few can identify the problem. > ^ I think you meant "enabled" here? > > Just in case the cover letter goes to the changelog... Correct. Another solution here would be to increase the threshhold so that 4 socket machines do not enable zone reclaim by default. The larger the NUMA system is the more memory is off node from the perspective of a processor and the larger the hit from remote memory. On the other hand: The more expensive we make reclaim the less it makes sense to allow zone reclaim to occur. -- 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>