Building parallel simulations from serial simulators

In order for parallel discrete event simulation (PDES) to have practical impact, PDES tools must hide the complexities of time synchronisation from users and provide capabilities approaching those of industrial quality serial simulators. Typically, PDES tools have been started from scratch thereby requiring a modeler to learn a new and unfamiliar modeling tool. This note describes a parallel simulation tool, the Utilitarian Parallel Simulator, U.P.S. that is distinguished from the above mentioned tools in that it is built on top of an existing, industrial quality serial simulator, CSIM. U.P.S. extends the standard CSIM modeling language by providing a simple and natural mechanism for submodels running on different processors to communicate with one another. The user need not be concerned with time synchronisation, save for specifying which algorithm to use, nor need the user make calls to a low level interprocessor communications library (e.g. a message-passing library such as MPI). U.P.S. was implemented without making any changes to the existing CSIM simulation engine. As such, it implements conservative time synchronisation algorithms. As CSIM has been ported to many uniprocessor platforms, and since U.P.S. is implemented using the MPI standard, U.P.S. is potentially portable to many multiple processor systems. It has been tested and run on two such platforms: the IBM SP2 and the Intel Paragon.