Messages in this thread | | | Date | Tue, 3 May 2005 08:36:51 -0700 | From | Grant Grundler <> | Subject | Re: [openib-general] Re: RDMA memory registration |
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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.
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