[Mpi3-hybridpm] First cut at slides

Jeff Squyres (jsquyres) jsquyres at cisco.com
Fri Jun 21 07:35:34 CDT 2013

On Jun 20, 2013, at 6:20 PM, Steve Oyanagi <sko at cray.com> wrote:

> 1. Can slides be expanded or can some one explain why the items in
>   question are desirable?  (i.e. use cases)  One case is libraries,
>   but I suspect there are others.

Sorry, yes, these slides assume that the reader has been attending the hybrid working group calls; they are not meant for the general forum.  :-)

The main motivating issue is the mixing of *multiple* MPI-aware libraries in a single application.  Such libraries may or may not be aware of the other MPI-aware libraries.

> 2. What does it mean if the first thread calls MPI_Init_thread with
>   required=MPI_THREAD_FUNNELD, then a later thread calls MPI_Init_thread
>   (MPI already initialized, now in "epoch" in slide-speak) with
>   required=MPI_THREAD_MULTIPLE?  Does the second call see an error?
>   What does second call return for provided?

That is up to the implementation, but I suspect that most will return in provided whatever was returned at the first call to MPI_INIT_THREAD.

> 3. Slide 13 seems to imply that the implementation doesn't need to
>   actually implement an intermediate finalize/initialization, just
>   allow the calls.  Is that correct?  Does that satisfy the use
>   cases?

Yes, that is one possible implementation.

Jeff Squyres
jsquyres at cisco.com
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