[openib-general] Reregister Memory Region Verb

[Fab Tillier]

> From: Caitlin Bestler [mailto:caitlinb at broadcom.com]
> Sent: Wednesday, January 25, 2006 10:06 AM
> 
> Fab Tillier wrote:
> >> From: Caitlin Bestler [mailto:caitlinb at broadcom.com]
> >> Sent: Wednesday, January 25, 2006 9:22 AM
> >>
> >>>> although we would prefer that it wouldn't block if possible
> >>>
> >>> mmm. All the current memory registration verbs both user and kernel
> >>> are blocking, is it an issue for you?
> >>>
> >>
> >> If you need to do memory registrations in a context where blocking is
> >> not an option then you really need FMR work requests as in RDMAC and
> >> InfiniBand 1.2 verbs.
> >
> > No.  The blocking semantics of memory registration APIs is a
> > deliberate design choice and not a limitation of the
> > hardware.  It is possible (though more
> > complicated) to make the API asynchronous.  No existing IB
> > stack to date has ever done so, however.
> >
> > - Fab
> 
> If asynchronous memory registration (via work request) is
> such a bad idea then why is it part of both the RDMAC iWARP
> and InfiniBand 1.2 verb specifications?

You misunderstood me.  I didn't say anything about FMR being a bad idea, just
that regular MRs could be made to work in a non-blocking manner.  Non-blocking
calls don't require FMR, it could be done without.

- Fab