Single Program Multiple Data (SPMD)

The development of the first SPMD version of Radioss is started in 1994. The version became a real alternative to SMP version after a long period of parallelization and optimization of the code. In fact, the scalability of the version is much better than the SPM version. The SPMD version allows using more processors with a better efficiency. It makes possible to use up to 64 processors. In addition, all Radioss Crash options are available in this version including "Arithmetic Parallel" option.

The principle of program is based on Single Program Multiple Data, where the same program runs with different data. Radioss Starter carries out domain decomposition. Then, Radioss Engine has just to send data to different processors in an initialization step. Thereafter, each program runs over each sub domain. It is necessary to communicate information between processors to manage data on the border of domains. This is carried out in Radioss using MPI (Message Passing Interface) library.

図 1 illustrates the architecture of multi-processor computers with distributed memory. The Radioss SPMD version runs independently to architecture of memory as well on the computers with shared memory or distributed memory or a set of work stations in a network.

図 1. Architecture with Distributed Memory