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

[Cownie, James H]

A simpler change which would seem to achieve the desired clarification
would be :- 

   MPI_THREAD_FUNNELED The process may be multi-threaded, but only the
main             
   thread is allowed to make MPI calls.

(and you could add 
   If other threads make MPI calls the behavior is undefined.
 if you want to be verbose about it).

-- Jim

James Cownie <james.h.cownie_at_[hidden]>
SSG/DPD/PAT
Tel: +44 117 9071438

> -----Original Message-----
> From: mpi-21-bounces_at_[hidden] [mailto:mpi-21-bounces_at_[hidden]]
On
> Behalf Of Rolf Rabenseifner
> Sent: 31 January 2008 14:31
> To: mpi-21_at_[hidden]
> Subject: [mpi-21] Ballot 4 - MPI_THREAD_FUNNELED - was Re: Attending,
> topics, etc
> 
> 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)
> _______________________________________________
> mpi-21 mailing list
> mpi-21_at_[hidden]
> http://lists.cs.uiuc.edu/mailman/listinfo/mpi-21
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