Re: [PATCH 0/7] Sparsemem Virtual Memmap V5

Christoph Lameter
2007-07-14T15:07:43Z

On Sat, 14 Jul 2007, Nick Piggin wrote:

> Isn't it still possible that you could have TLB pressure that would
> result in lower performance? I wonder why the large page support for
> ia64 was shelved?

16M Large memmap support was shelved because 16M is too large a size for
a vmemmap block. It results in the vmemmap overlapping multiple nodes.

The TLB pressure for the 16k support is the same since its the same
algorithm. We are measuring discontig/vmemmap 16k against sparse/vmemmap
16k here.

We would likely see a different if we would compare sparsemem vs.
sparse/vmemmap. Then there may be a difference in TLB pressure. But 16k
discontig/vmemmap is the current default on IA64.