On Thu, Dec 12, 2013 at 12:49 PM, Alex Thorlton <athorlton@xxxxxxx> wrote: > > > Is there a setting that will turn off the must-be-the-same-node > > behavior? There are workloads where TLB matters more than cross-node > > traffic (or where all the pages are hopelessly shared between nodes, > > but hugepages are still useful). > > That's pretty much how THPs already behave in the kernel, so if you want > to allow THPs to be handed out to one node, but referenced from many > others, you'd just set the threshold to 1, and let the existing code > take over. > Right. I like that behavior for my workload. (Although I currently allocate huge pages -- when I wrote that code, THP interacted so badly with pagecache that it was a non-starter. I think it's fixed now, though.) > > As for the must-be-the-same-node behavior: I'd actually say it's more > like a "must have so much on one node" behavior, in that, if you set the > threshold to 16, for example, 16 4K pages must be faulted in on the same > node, in the same contiguous 2M chunk, before a THP will be created. > What happens after that THP is created is out of our control, it could > be referenced from anywhere. In that case, I guess I misunderstood your description. Are saying that, once any node accesses this many pages in the potential THP, then the whole THP will be mapped? --Andy -- 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>