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Subject: Re: [OMPI users] Bug with 1.2.5?
From: George Bosilca (bosilca_at_[hidden])
Date: 2008-03-17 12:51:38

I'm not very familiar with Fortran 90, but the code looks wrong to me.
Here is a snippet from the code:

      call MPI_ISEND(VTMP,int(NCFACES(I)),MPI_FP,NZINT(I)-1, &


The problem seems to come from the fact that you start a non blocking
send and then you release the buffer, which is completely illegal !!!
The free should happen only once you know the send is completed, which
means after the MPI_Waitall.

This works with MPICH because they buffer data in some cases. And
works for Open MPI on small problem sizes, because then the message
can be send directly without buffering. However, once you're over the
eager limit, a rendez-vous message is required, and the MPI_Isend will
be completed only later.


On Mar 17, 2008, at 12:33 PM, Grismer, Matthew J Civ USAF AFMC AFRL/
RBAC wrote:

> I've attached the requested configuration and ompi_info output, as
> well
> as the actual error messages that appear (run.out) when the code is
> run.
> I traced it down to the section of code included that is in
> fail_section.F.
> The platform is a Mac Pro running Mac OS X 10.5.2, but I also tried it
> on Mac OS X Server 10.4.11 (Xserve Xeon) with the same result. Also
> tried compiling OpenMPI with the Intel C/C++ compilers (version
> 10.1.012), same result.
> The code has been run without issue on numerous HPC platforms, and
> runs
> with OpenMPI on this platform for small problems. Issue shows up when
> running larger problems. Using MPICH2 on this platform with same large
> problem runs fine.
> The issue appears to occur when calling the MPI_WAITALL statement at
> the
> end of the code section; the MPI_IRECV and MPI_ISEND statements
> complete.
> Any help is greatly appreciated.
> _____________________________________________________
> Matthew Grismer
> <
> run
> .out
> >
> <
> config
> .log
> .gz
> >
> <
> fail_section
> .F><mpi_info.txt.gz>_______________________________________________
> users mailing list
> users_at_[hidden]

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