On 12/11/2013 01:09 PM, Johannes Weiner wrote: > Dave Hansen noted a regression in a microbenchmark that loops around > open() and close() on an 8-node NUMA machine and bisected it down to > 81c0a2bb515f ("mm: page_alloc: fair zone allocator policy"). That > change forces the slab allocations of the file descriptor to spread > out to all 8 nodes, causing remote references in the page allocator > and slab. > > The round-robin policy is only there to provide fairness among memory > allocations that are reclaimed involuntarily based on pressure in each > zone. It does not make sense to apply it to unreclaimable kernel > allocations that are freed manually, in this case instantly after the > allocation, and incur the remote reference costs twice for no reason. > > Only round-robin allocations that are usually freed through page > reclaim or slab shrinking. > > Bisected-by: Dave Hansen <dave.hansen@xxxxxxxxx> > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: <stable@xxxxxxxxxx> 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>