Re: Demand paging for memory regions

Jesse Barnes
2008-02-14T00:14:08Z

On Wednesday, February 13, 2008 3:43 pm 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?
>
> The example I am thinking about is rawio (Oracle's
> mlock'ed SHM regions are handed to rawio, isn't it?).
> My understanding of how rawio works in Linux is quite
> dated though ...

We're doing something similar in the DRM these days... We need big chunks of
memory to be pinned so that the GPU can operate on them, but when the
operation completes we can allow them to be swappable again. I think with
the current implementation, allocations are always pinned, but we'll
definitely want to change that soon.

Dave?

Jesse