Hello Andre,
It may be possible that your openmpi does not support threaded MPI-calls (if these are happening). I had a similar problem, and it was traced to this cause. If you installed your openmpi from available repositories, chances are that you do not have thread-support.
Here's a small script that you can use to determine whether or not you have thread support:
#include <mpi.h>
#include <iostream>
int main(int argc, char **argv)
{
 int myrank;
 int desired_thread_support = MPI_THREAD_MULTIPLE;
 int provided_thread_support;
 MPI_Init_thread(&argc, &argv, desired_thread_support, &provided_thread_support);
 /* check if the thread support has been provided */
 if (provided_thread_support!=desired_thread_support)
   {
     std::cout << "MPI thread support not available! Aborted. " << std::endl;
     exit(-1);
   }
 MPI_Finalize();
 return 0;
}
Compile and build as usual, using multiple processors.
Maybe this helps. If you do discover that you do not have support available, you will need to rebuild MPI with --enable-mpi-threads=yes flag.
HTH.
Devendra
________________________________
From: "Theiner, Andre" <andre.theiner_at_[hidden]>
To: "users_at_[hidden]" <users_at_[hidden]>
Sent: Monday, 16 January 2012, 11:55
Subject: [OMPI users] mpirun hangs when used on more than 2 CPUs
Â
Hi everyone,
may I have your help on a strange problem?
High performance computing is new to me and I have not much idea about OpenMPI and OpenFoam (OF) which uses the “mpirun†command.
I have to support the OF application in my company and have been trying to find the problem since about 1 week.
The versions are openmpi-1.3.2 and OF 2.0.1 which are running on openSUSE 11.3 x86_64.
The computer is brand new, has 96 GB RAM, 12 CPUs and was installed with Linux some weeks ago.
I installed OF 2.0.1 according to the vendors instructions at http://www.openfoam.org/archive/2.0.1/download/suse.php.
Â
Here the problem:
The experienced user tested the OF with a test case out of one of the vendors tutorials.
He only used the computing power of his local machine “caelde04†, no other computers were accessed by mpirun.
Â
He found no problem when testing in single “processor mode†but in “multiprocessor mode†his calculations hangs when he distributes
the calculations to more than 2 CPUs. The OF vendor thinks this is an OpenMPI problem somehow and that is why I am trying to get
help from this forum here.
I attached 2 files, one is the “decomposeParDict†which resides in the “system†subdirectory of his test case and the other is the log file
from the “decomposePar†command and the mpirun command “mpirun -np 9 interFoam –parallelâ€.
Do you have an idea where the problem is or how I can narrow it down?
Thanks much for any help.
Andre
Â
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