[mpich-devel] call PMI before MPI_Init_thread?

[Jeff Hammond]

Is it valid in _MPICH_ to make calls to PMI before MPI is initialized?
 I am interested in PMI_Init, PMI_Get_size and PMI_Get_rank.

The motivating use case is to initialize e.g. half my ranks with
MPI_THREAD_FUNNELED and the other half with MPI_THREAD_MULTIPLE but
not use MPMD launching.

I have two reasons for wanting to do it this way.  First, it is
otherwise unnecessary to use MPMD since I can branch at the top of my
code and meet the requirements of FUNNELED and MULTIPLE.  Second, I
might be interested in running my code on a supercomputer with an
MPICH-based MPI implementation that does not support MPMD launching in
an unrestricted manner.

If MPICH can handle this, then I will worry about whether or not the
aforementioned supercomputer can.  It is my assumption that, if MPICH
cannot handle this, then the MPICH derivative in question cannot
either.

Thanks,

Jeff

-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/