[Mpi3-hybridpm] MPI + threads / MPI +OpenMP

[Bronis R. de Supinski]

Marc:

Hmm. Interesting reading.

If the thread support level is MPI_THREAD_SINGLE,
must MPI_ENDPOINT_CREATE be called before more than
one thread exists in the process? I assume it is
erroneous to have more threads in the process than
generated (allocated?) endpoints.

The OpenMP part does not clearly incorporate that
OpenMP threads are distinct from kernel or user
threads. OpenMP threads go away when a parallel
region ends. An implementation can choose to
implement them on top of more permanent threads
(and most do). However, you are not guaranteed
any fixed relationship between the numbering
of threads in two distinct parallel regions
(there are good reasons for this that I could
go into if anyone cares). Maybe this does not matter
for your proposal (I have only skimmed the later
part and need to cogitate on it further). It may
be possible to have OpenMP extensions that change
this aspect of the language; do you require them
or at least find them useful?

Are there other extensions to OpenMP that would
be useful? We are actively working on OpenMP 4.0...

Bronis




On Wed, 5 Aug 2009, Snir Marc wrote:

> I attach a detailed proposal for a possible hybrid model that, I
> believe, would be easy to implement. The proposal draft is attached. I
> hope it can be discussed by this working group.
>
>
> Marc Snir
> Michael Faiman and Saburo Muroga Professor
> Department of Computer Science, University of Illinois at Urbana
> Champaign
> 4323 Siebel Center, 201 N Goodwin, IL 61801
> Tel (217) 244 6568
> Web http://*www.*cs.uiuc.edu/homes/snir
>
>