[mpi-21] Ballot 4 - MPI_THREAD_FUNNELED - was Re: Attending, topics, etc

[Rolf Rabenseifner]

This is a proposal for MPI 2.1, Ballot 4.

I'm asking especially 
  Greg Lindahl,
the participants of the email-discussion in 2007, to review this proposal.

This is a follow up to:
  Which thread is the funneled thread?
  in http://www.cs.uiuc.edu/homes/wgropp/projects/parallel/MPI/mpi-errata/index.html
with mail discussion in
  http://www.cs.uiuc.edu/homes/wgropp/projects/parallel/MPI/mpi-errata/discuss/funneled/
___________________________________

Proposal:
MPI-2.0 Sect. 8.7.3, MPI_Init_thread, page 196, lines 25-26 read:

  MPI_THREAD_FUNNELED The process may be multi-threaded, but only 
  the main thread will make MPI calls (all MPI calls are "funneled" 
  to the main thread).

but should read:

  MPI_THREAD_FUNNELED The process may be multi-threaded, but only 
  the main thread will make MPI calls (all MPI calls are "funneled" 
  to the main thread, e.g., by using the OpenMP directive "master"
  in the application program).
___________________________________
Rationale for this clarification from the email from Greg Lindahl:
  The existing document doesn't make it clear that
  the MPI user has to funnel the calls to the main thread; 
  it's not the job of the MPI library. I have seen multiple 
  MPI users confused by this issue, and when I first read 
  this section, I was confused by it, too.
___________________________________

 
Best regards
Rolf

Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner_at_[hidden]
High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)