[ofa-general] Re: [ewg] RFC: Do we wish to take MPI out of OFED?

[Jeff Squyres]

On Jun 8, 2009, at 6:59 AM, Todd Rimmer wrote:

> I agree with DK from OSU.  There are clear advantages to having MPI  
> included with OFED.  Not only will it make testing of a complete  
> solution easier by both OFED and MPI suppliers,
>

Can you specify how, specifically?

Remember that all that Open MPI and MVAPICH do is provide SRPMs.   
There is no co-mingling of development / source trees, for example.   
You seem to be blurring the distinction between co-development of MPI 
+OpenFabrics and shipping OFED.  Developing the two together is a Good  
Thing -- and that happens.  But that is unrelated to shipping the  
MPI's in OFED.

As has been specified multiple times on this thread, using MPI to test  
verbs is a Good Thing and it can easily be maintained without  
distributing MPI in OFED.

> but it will also improve ease of use for end users.
>

Can you specify how, specifically?

Recall that:

- Open MPI users get a stripped-down version with several important  
features disabled
- At least one user has chimed in that they install MPI separately  
from OFED for a variety of reasons (I have seen this at customer sites  
as well)

> As DK points out there are continual improvements in MPIs which may  
> depend on bug fixes and/or new features in newer versions of OFED.  
> Identifying a known good combination will be important to most end  
> users, etc.
>

Easy to do in documentation and/or in the technology of the MPI  
implementations themselves.  The verbs API should allow this kind of  
run-time checking as a matter of course (and it seems to allow it well  
enough).

Additionally -- and your later comments seemed to support it --  
possibly the most important combination that needs to work is that of  
<latest OFED> + <latest MPI>, which will continue to work because OFED  
would be insane to remove MPI from its testing/QA/release process.

-- 
Jeff Squyres
Cisco Systems