[ofa-general] RDS flow control

[Olaf Kirch]

On Monday 12 May 2008 18:57:38 Jon Mason wrote:
> As part of my effort to get RDS working for iWARP, I will be working on the 
> RDS flow control.  Flow control is needed for iWARP due to the fact that 
> iWARP connections terminate if there is no posted recv for an incoming 
> packet.  IB connections do not have this limitation if setup in a certain 
> way.  In its current implementation, RDS sets the connection attribute 
> rnr_retry to 7.  This causes IB to retransmit until there is a posted recv 
> buffer. 

I think for the initial implementation, it is fine for iWARP to just
fail the connect when that happens, and re-establish the connection.

If you use reasonable defaults for the send and recv queues, receiver
overruns should be relatively rare.

Once everything else works, let's revisit the flow control part.

> I am still in the very early stages of implementing this.  So any pointers to 
> RDS documentation (or a RDS git tree) would be very helpful.  I have a small 
> IB setup to test this on, so anyone willing to test it when I am done would 
> be helpful as well.

The main RDS repo is the OFED tree. If you want to integrate with my work tree,
let me know and I'll feed your patches into my tree at
http://www.openfabrics.org/git/?p=~okir/ofed_1_3/linux-2.6.git

Olaf
-- 
Olaf Kirch  |  --- o --- Nous sommes du soleil we love when we play
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