On Tue, Apr 08, 2014 at 09:14:05AM -0500, Christoph Lameter wrote: > On Mon, 7 Apr 2014, Mel Gorman wrote: > > > zone_reclaim_mode causes processes to prefer reclaiming memory from local > > node instead of spilling over to other nodes. This made sense initially when > > NUMA machines were almost exclusively HPC and the workload was partitioned > > into nodes. The NUMA penalties were sufficiently high to justify reclaiming > > the memory. On current machines and workloads it is often the case that > > zone_reclaim_mode destroys performance but not all users know how to detect > > this. Favour the common case and disable it by default. Users that are > > sophisticated enough to know they need zone_reclaim_mode will detect it. > > Ok that is going to require SGI machines to deal with zone_reclaim > configurations on bootup. Dimitri? Any comments? > The SGI machines are also likely to be managed by system administrators who are both aware of zone_reclaim_mode and know how to evaluate if it should be enabled or not. The pair of patches is really aimmed at the common case of 2-8 socket machines running workloads that are not NUMA aware. -- Mel Gorman SUSE Labs -- 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>