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

[Hal Rosenstock]

On Tue, 2005-09-20 at 19:39, Sean Hefty wrote:
> > What application/ULP are you running ?
> 
> He's running a modified version of dtest over DAPL that times RDMA reads from 
> the post time to poll CQ completion.
> 
> The test setup is actually a little more complex.  The latencies for the runs 
> with the various PSNs were:
> 
> 1 - 60us
> 0x10000 - 60us (first run)
> 0x10000 - 100us (subsequent runs)
> 0x20000 - 100us (first run)
> 0x20000 - 140us (subsequent runs)
> 0x40000 - 140us (first run)
> 0x40000 - 220us (subsequent runs)
> 
> The application halts and is re-started between each run, and the QP is 
> different each time.  The only change from run to run is the PSN.

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.

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

-- Hal