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    SubjectRe: [openib-general] Re: RDMA memory registration
    On Tue, May 03, 2005 at 09:42:12AM +0100, David Addison wrote:
    > >This doesn't scale well as more cards are added to the box.
    > >I think I understand why it's good for single cards though.
    >
    > With the IOPROC patch the device driver hooks are registered on a per
    > process or perhaps better still, a per VMA basis.

    I was originally thinking the registrations are global (for all memory)
    and not per process. Per process or per VMA seems reasonable to me.

    > And for processes/VMAs where there are no registrations the overhead
    > is very low.

    Yes - thanks. I'm still reading the LKML thread you started:
    http://lkml.org/lkml/2005/4/26/198

    In particular, the comments from Brice Goglin:
    http://lkml.org/lkml/2005/4/26/222

    openib.org folks can find the IOPROC patch for 2.6.12-rc3 archived here:
    http://lkml.org/lkml/diff/2005/4/26/198/1

    > With multiple cards in a box, all using different device drivers,
    > I guess there could end up being multiple registrations per process/VMA.
    > But I'm not sure this will be a common case for RDMA use in real life.

    I agree. Gateways between fabrics is the only case I can think of.
    This won't be a problem until someone at a large national lab tries
    to connect two "legacy" fabrics together.

    thanks,
    grant
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