Clusters of symmetric shared memory multiprocessors (SMPs) are fast becomin
g a highly available platform for parallel computing. There is a need for a
uniform programming paradigm that allows users to transparently extend par
allelism across multiple SMP nodes. A shared memory paradigm leverages the
available hardware to handle sharing within an SMP, in addition to providin
g programming ease. Software distributed shared memory systems support the
illusion of shared memory across the cluster via a software runtime layer b
etween the application and the hardware. This approach can potentially prov
ide a cost-effective alternative to larger hardware shared memory systems f
or executing certain classes of workloads. We describe here one such system
and discuss its interface, performance and portability through an example
real-world application from the scientific domain.