[Mpi3-hybridpm] First cut at slides

Steve Oyanagi sko at cray.com
Fri Jun 21 09:36:13 CDT 2013

Hi Jeff,

Thanks for the use case info, that was really helpful.

Your response to the rest of the questions makes me realize
that I am reading too much into the proposal and not
catching where decisions are left to the implementation.

	- Steve

On 06/21/2013 07:35 AM, Jeff Squyres (jsquyres) wrote:
> 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.

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