[ofw] Re: [ewg] RE: SC'09 BOF - Meeting notes and Final Slides

[Fab Tillier]

Hi Roland

Roland Dreier wrote on Thu, 19 Nov 2009 at 11:19:02

> 
>> WinOF has asynchronous interfaces for modify QP, and limited testing
>> has shown that it can improve connection times.  QP transitions are
>> probably the second largest component of connection setup after the SA.
>>  Since the RDMA CM already provides an asynchronous interface, even
>> existing apps may be able to be able to gain some benefit from this.
> 
> can't anyone get async modify QP today on any platform by just doing the
> operation in another thread (or thread pool)?  It seems that the
> operations themselves are heavy enough that thread dispatch, locking etc
> is going to be significant overhead.

Why should clients have to emulate asynchronous behavior when the (Mellanox) HCA command interface is already asynchronous?
 
I would prefer any threading be added to the HCA driver in the kernel, and not as threads in each process.  That would enable a seamless transition to a better driver model in the future.

-Fab