[openib-general] rdma_cm branch

[Steve Wise]

On Wed, 2006-10-04 at 10:17 -0700, Sean Hefty wrote:
> >Guys, I must be confused.  I thought the private data _was_ passed up in
> >the ESTABLISHED event on the active side.  We have tools in the
> >perftools directory that utilize this.   What am I missing here?
> 
> When a user calls rdma_connect(), they specific connection parameters (like
> responder_resources and initiator_depth) through a struct rdma_conn_param.
> These parameters are NOT given to the user when the connect request event is
> reported.
> 
> The issue is: are these values needed by the user during connection
> establishment?  If yes, then how do we export them to the user.
> 

I understand now.  

For iWARP, the key parameter is setting your local QP's ORD (initiator
resources) to <= your peer's IRD (responder resources) to avoid
overflowing the peers incoming rdma read queue.  I think the iWARP
devices must support setting ORD even after the connection is setup and
the QP is in RTS, so the connection _could_ be setup (qp moved to RTS)
and then the QP modified to the appropriate settings after querying to
get the peer's params.  But I think it seems more natural to deal with
this at connection setup time.

It would be nice, IMO, for the RDMA CM to handle this under the covers
and setup the QP appropriately.  Thus the parameters need not be passed
to the consumer... 

My 2 cents.