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

Thu Jan 31 09:54:55 CST 2008

Because that's how it's always been. We're not adding a restriction with
the change, merely clarifying the existing restriction.

-- Jim

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

________________________________

From: mpi-21-bounces_at_[hidden] [mailto:mpi-21-bounces_at_[hidden]] On
Behalf Of Richard Graham
Sent: 31 January 2008 15:51
To: Mailing list for discussion of MPI 2.1
Subject: Re: [mpi-21] Ballot 4 - MPI_THREAD_FUNNELED - was Re:
Attending, topics, etc

Why restrict this to a standard specified thread (main thread), why not
word it
 as a singe thread, and let the app decide what thread this is, based on
what
 ever criteria it wants to use to select this thread ?

Rich

On 1/31/08 10:27 AM, "Richard Treumann" <treumann_at_[hidden]> wrote:

How about::
MPI_THREAD_FUNNELED The process may be multi-threaded, but the
application
must insure that only the main thread makes MPI calls.

Dick Treumann  -  MPI Team/TCEM            
IBM Systems & Technology Group
Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846         Fax (845) 433-8363

mpi-21-bounces_at_[hidden] wrote on 01/31/2008 09:44:08 AM:

> 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]]
<mailto:mpi-21-bounces_at_[hidden]%5d> 
> 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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