[ofa-general] Re: [ewg] Re: [OMPI devel] Re: OMPI over ofed udapl - bugs opened

[Michael S. Tsirkin]

> Quoting Jeff Squyres <jsquyres at cisco.com>:
> Subject: Re: [ewg] Re: [OMPI devel] Re: OMPI over ofed?udapl -?bugs?opened
> 
> On May 10, 2007, at 10:28 AM, Michael S. Tsirkin wrote:
> 
> >>What is the advantage of this approach?
> >
> >Current ipoib cm uses this approach to simplify the implementation.
> >Overhead seems insignificant.
> 
> I think MPI's requirements are a bit different than IPoIB.  See  
> Gleb's response. It is not uncommon for MPI apps to have connections  
> open to many peers simultaneously.

You mean, hundreds of QPs between the same pair of hosts?
Yes, in this case you might start running out of QPs.

> Registered memory / internal  
> buffering usage is a Big Deal in the MPI / HPC community.

I don't see the connection with the # of QPs.
They are very cheap in memory.

-- 
MST