[openib-general] QP with large starting sequence adds latency to RDMA READ???

[Sean Hefty]

Hal Rosenstock wrote:
> Might it be some timeout being hit before this starts working ?
> 
> Not sure I understand it but it looks like the 
> CM starting_psn is set to ep_ptr->qp_handle->qp_num in the uDAPL CM.

He is over-riding this value before modifying the QP.

> Don't know if that has anything to do with this but shouldn't this be
> the same PSN set for the QP ?

Not sure what the problem is.  Initially, he was seeing a steady increase in 
RDMA read latency of 40 us per run.  He narrowed it down to setting the PSN. 
Hard-coding the PSN to 1 eliminated the latency issue.  Setting it to higher 
values cause the RDMA read latency to increase.

- Sean