[ofa-general] post_recv question

[Ralph Campbell]

On Thu, 2008-02-21 at 13:32 -0600, Steve Wise wrote:

> > I think you are making sense.  There is an indeterminate race
> > between post_recv() returning to the application and when
> > a packet being received by the HCA might be able to use
> > that buffer. There are no ordering guarantees
> > between messages sent on one QP and another so the application
> > can't easily use a different QP to advertise posted buffers (credits).
> > That is why the IB RC protocol does this for you in band if the RC QP
> > is using a dedicated receive queue but not a shared receive queue.
> > 
> 
> Do you mean the IB RC protocol advertises credits as part of the 
> transport protocol?

Yes. See chapter 9.7.7.2 in Rel 1.2 vol. 1.