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Subject: Re: [OMPI users] mpirun hangs when used on more than 2 CPUs
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2012-01-17 16:53:05


You should probably also run the ompi_info command; it tells you details about your installation, and how it was configured.

Is it known that OpenFoam uses threads with MPI?

On Jan 17, 2012, at 9:08 AM, Ralph Castain wrote:

> You might first just try running a simple MPI "hello" to verify the installation. I don't know if OF is threaded or not.
>
> Sent from my iPad
>
> On Jan 17, 2012, at 5:22 AM, John Hearns <hearnsj_at_[hidden]> wrote:
>
>> Andre,
>> you should not need the OpenMPI sources.
>>
>> Install the openmpi-devel package from the same source
>> (zypper install openmpi-devel if you have that science repository enabled)
>> This will give you the mpi.h file and other include files, libraries
>> and manual pages.
>>
>> That is a convention in Suse-style distros - the devel package
>> contains the stuf you need to 'develop'
>>
>> On 17/01/2012, Theiner, Andre <andre.theiner_at_[hidden]> wrote:
>>> Hi Devendra,
>>> thanks for your interesting answer, up to now I expected to get a fully
>>> operational openmpi installation package
>>> by installing openmpi from the “science” repository (
>>> http://download.opensuse.org/repositories/science/openSUSE_11.3%94 ).
>>> To compile your script I need to have the openmpi sources which I do not
>>> have at present, I will try to get them.
>>> How do I compile and build using multiple processors?
>>> Is there a special flag which tells the compiler to care for multiple CPUs?
>>>
>>> Andre
>>>
>>>
>>> From: users-bounces_at_[hidden] [mailto:users-bounces_at_[hidden]] On
>>> Behalf Of devendra rai
>>> Sent: Montag, 16. Januar 2012 13:25
>>> To: Open MPI Users
>>> Subject: Re: [OMPI users] mpirun hangs when used on more than 2 CPUs
>>>
>>> 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
>>>
>>>
>>> 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.
>>>
>>> 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.
>>>
>>> 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 –parallel”.
>>> Do you have an idea where the problem is or how I can narrow it down?
>>> Thanks much for any help.
>>>
>>> Andre
>>>
>>>
>>> _______________________________________________
>>> users mailing list
>>> users_at_[hidden]<mailto:users_at_[hidden]>
>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>
>>
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>
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-- 
Jeff Squyres
jsquyres_at_[hidden]
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