Performance of a mixed shared/distributed memory parallel network simulator

Designing fast parallel discrete event simulation systems for shared-memory parallel computers is simplified by the efficient communication operations enabled by the common memory space. The difficulties involved in designing large shared-memory computers and the resulting high cost of even modest size systems has led to the proliferation of computer systems consisting of small shared-memory computers connected via low-latency message-passing interconnection networks. This paper describes how a network simulation system using a simulation kernel optimized for high performance operation on shared-memory parallel computers has been extended to operate on computers that mix shared-memory and message-passing paradigms. Results are presented showing that the system can achieve over 60 million simulated packet transmissions per second on 32 4-processor nodes. The results demonstrate the advantage of using a mixture of shared-memory and message-passing over using only message-passing in many cases.