[openib-general] [PATCH] [RFC] dapltest change for iwarp

[Steve Wise]

On Fri, 2006-04-28 at 11:32 -0700, Sean Hefty wrote:
> Steve Wise wrote:
> > This patch changes the dapltest transaction test to force the client
> > side (the side that dat_ep_connect()) to send the first RDMA message.
> > This ensures that the IWARP MPA protocol requirements are met.
> > 
> > I'm presenting this for discussion and possible inclusion in the
> > trunk.  
> > 
> > A transport independent application should be designed to work over all
> > transports and should therefore utilize the only the common features.
> > This implies that the application should always initiate RDMA exchanges
> > starting with the client, to avoid MPA problems.
> 
> What if someone comes up with an RDMA transport that requires the server side to 
> send the first message?
> 

We shoot them. ;-)

Seriously... Good point.

The Chelsio RNIC has this issue.  If the server sends the first FPDU
_before_ the client driver has moved the connection/qp into RDMA mode,
then the data is placed as streaming data and the connection must be
terminated (dapltest 6 exposes this intermittently).  Ammasso doesn't
have this issue, but other RNIC's probably will.  

One thing I'm experimenting with is to delay the ESTABLISHED event on
the server side until the first FPDU is received.  However, we still
probably need a way for an application to know whether the client has to
send first (or the server as you pointed out).

I believe rnic-pi has an attribute that indicated this behavior...

 
Steve.