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Subject: [OMPI users] OpenMPI-1.2.8 issues on 64-bit Itanium platforms (IA64)
From: Ravi Manumachu (manumachu.reddy_at_[hidden])
Date: 2008-11-17 03:11:25

Dear Users, Support Engineers,

I am using OpenMPI-1.2.8 on two sets of machines. The first set has three 64-bit Itanium machines and the second set has three 32-bit i386 machines. The machines in the first set are multicores. All the machines are connected by 1 Gigabit Ethernet.

My complaint is I am observing large communication times between the machines, i.e., inter-node communications. My comparisions are with MPICH-1.2.7p1. I am attaching communication times for simple Ping experiments. The Ping application is attached in the file 'MPI_ping.c'. However, my real application is parallel matrix-matrix application where I am observing communication times some five times more than the computation times.

On both the sets of machines, OpenMPI is installed using the simplest configure command, which is "configure --prefix=<...>". Could you please tell me if I should provide any special installation options for efficient communications?

All the information related to the tests is present in the ZIP file attached.

The platform information of the machines obtained using "uname -a" is printed below:

ia64$ uname -a
Linux rosebud08 2.6.9-42.EL #1 SMP Wed Jul 12 23:25:09 EDT 2006 ia64 ia64 ia64 GNU/Linux

i386$ uname -a
Linux rosebud04 2.6.9-42.0.2.ELsmp #1 SMP Wed Aug 23 00:17:26 CDT 2006 i686 i686 i386 GNU/Linux

The compiler used on all these machines is Intel 'icc' 9.1.046.

The CPU information for the Itanium machines is attached in the text file 'cpuinfo_ia64.txt'.

The installation information for the machines (ia64, i386) are attached in the files 'config_ia64.log' and 'config_i386.log' respectively.

The output from the ompi_info command for the machines (ia64, i386) are attached in the files 'ompi_info_ia64.log' and 'ompi_info_i386.log' respectively.

The experiments results are shown at the end of the mail (also in the text file eresults.txt). I am also presenting below results using MPICH-1.2.7p1, whose inter-node communication times between two ia64 nodes are faster. As you can see, OpenMPI communications are expensive.

My question is are there any special installation options to use for ia64 platforms? I would be using a mix of ia64 and i386 platforms in the future. Are there any issues that need to be taken care of?

Thanking you for your cooperation.

Best regards
Ravi Reddy
School of Computer Science and Informatics
University College Dublin

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