Re: [ofa-general] Re: Demand paging for memory regions

Christoph Lameter
2008-02-14T19:35:48Z

On Wed, 13 Feb 2008, Kanoj Sarcar wrote:

> Oh ok, yes, I did see the discussion on this; sorry I
> missed it. I do see what notifiers bring to the table
> now (without endorsing it :-)).
>
> An orthogonal question is this: is IB/rdma the only
> "culprit" that elevates page refcounts? Are there no
> other subsystems which do a similar thing?

Yes there are actually two projects by SGI that also ran into the same
issue that motivated the work on this. One is XPmem which allows
sharing of process memory between different Linux instances and then
there is the GRU which is a kind of DMA engine. Then there is KVM and
probably multiple other drivers.