[Beowulf] Sharing an array in an MPI program?

Tahir Malas tmalas at ee.bilkent.edu.tr
Thu May 24 08:05:03 PDT 2007

Hi all,
We have an 8-node cluster of SMP nodes, which have dual-quad core
processors. The network is Infiniband. Each process in our parallel FORTRAN
90 program holds an identical array that is used in all parts of the
program. However, when the size of the problem gets larger and larger, this
memory cost has started to become a memory bottleneck for us.
If all 8 processes in the same node could just read from the same memory
instead of holding their arrays, we would have significant memory gain. This
would be natural in a node if were to use OpenMP, but I wonder whether this
is somehow possible with only MPI? Distributing this array among the
processes is too expensive for us. We also know that passing to hybrid
programming (MPI + OpenMP) is a choice, but we look for simpler choices for
the time being.
Tahir Malas
Bilkent University 
Electrical and Electronics Engineering Department
Phone: +90 312 290 1385 

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