On Thu, Dec 12, 2013 at 12:49 PM, Alex Thorlton <[email protected]> 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
