[openib-general] [PATCH 0/4] Dispatch communication relatedevents to the IB CM

[Rimmer, Todd]

> Quoting r. Sean Hefty <sean.hefty at intel.com>:
> > Subject: RE: [PATCH 0/4] Dispatch communication relatedevents to the
IB
> CM
> >
> > >Perhaps we should pursue changing this in the IBTA spec.  Being
able to
> > >post to the SQ while in RTR makes handling of the Comm Est/RTU race
> with
> > >the CQ callback much easier to handle.
> > >
> > >It would be better if the IB spec permitted posting to the SQ in
RTR
> but
> > >indicated the SQ would not be processed until the QP moved to RTS.
I
> > >believe the present Mellanox silicon/firmware implements such
behavior.
> >
> > I think it would be simpler to transition the QP to RTS after
sending a
> REP,
> > with the restriction that a user may not post sends until an RTU is
> received, a
> > communication establish event occurs, or a receive message completes
on
> the QP.

This approach will not work.  If the QP is in RTS the Communication
established event will never be generated.  Hence the lost RTU case
would not be properly handled and the ULP would need to take on the
burden.  Its much better to isolate the solution to the CM and let the
ULP post to the send Q in RTR.

Todd Rimmer
Chief Systems Architect              SilverStorm Technologies
Voice: 610-233-4852                   Fax: 610-233-4777
TRimmer at SilverStorm.com        www.SilverStorm.com