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Subject: Re: [OMPI users] MPI_Init() and MPI_Init_thread()
From: Richard Treumann (treumann_at_[hidden])
Date: 2010-03-03 15:47:45


You are right Dave, FUNNELED allows the application to have multiple
threads but only the man thread calls MPI.

An OpenMP/MPI hybrid program that makes MPI calls only in between parallel
sections is usually a FUNNELED user of MPI

Thanks

Dick Treumann - MPI Team
IBM Systems & Technology Group
Dept X2ZA / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846 Fax (845) 433-8363

                                                                                                                             
  From: Dave Goodell <goodell_at_[hidden]>
                                                                                                                             
  To: Open MPI Users <users_at_[hidden]>
                                                                                                                             
  Date: 03/03/2010 03:08 PM
                                                                                                                             
  Subject: Re: [OMPI users] MPI_Init() and MPI_Init_thread()
                                                                                                                             
  Sent by: users-bounces_at_[hidden]
                                                                                                                             

On Mar 3, 2010, at 11:35 AM, Richard Treumann wrote:
> If the application will make MPI calls from multiple threads and
> MPI_INIT_THREAD has returned FUNNELED, the application must be
> willing to take the steps that ensure there will never be concurrent
> calls to MPI from the threads. The threads will take turns - without
> fail.
>
Minor nitpick: if the implementation returns FUNNELED, only the main
thread (basically the thread that called MPI_INIT_THREAD, see MPI-2.2
pg 386 for def'n) may make MPI calls. Dick's paragraph above is
correct if you replace FUNNELED with SERIALIZED.

-Dave

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