[openib-general] Re:[ULP] how to choose appropriate ULPs for application

[Libor Michalek]

On Wed, Jul 13, 2005 at 10:17:18AM -0700, Michael Krause wrote:
> At 06:39 AM 7/13/2005, James Lentini wrote:
> >On Tue, 12 Jul 2005, xg wang wrote:
> >
> >>     Frankly speaking, I can not distinguish the function of SDP and 
> >> DAPL. Since Lustre is a file system, it runs on kernel. So I think maybe 
> >> kDAPL is better.
> >
> >SDP stands for the Sockets Direct Protocol. The protocol is designed to 
> >support the Berkley Sockets API. This allows code already using the 
> >Sockets API to easily use InfiniBand by simply changing the socket type.
> 
> One clarification: SDP supports both synchronous and asynchronous 
> sockets.  The OpenGroup ICSC released the sockets extensions API a number 
> of months back that enables the full performance provided by SDP to be 
> tapped.  The SDP specifications can be found at the IBTA for IB and at the 
> RDMAC for RNIC web sites.

  I'd like to add that this SDP implementation does have asynchronous
sockets support in the form of linux 2.6 AIO, and there's even an
example of how to use AIO with sockets. Although I don't have time in
the immediate future it should be rather straight forward to implement
the OpenGroup ICSC sockets extensions API on top of linux AIO without
needing to make any kernel modifications. (with the possible exception
of the map/unmap calls) If anyones interested in doing this, I'd be
happy to discuss/help. 

  As you say the full performance only shows through when using
asynchronous sockets.


-Libor