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Proceedings Fourteenth Workshop on Parallel and Distributed Simulation (2000)
Bologna, Italy
May 28, 2000 to May 31, 2000
ISSN: 1087-4097
ISBN: 0-7695-0677-1
pp: 23
Thom McLean , Georgia Institute of Technology
Richard Fujimoto , Georgia Institute of Technology
Real-time distributed simulations, such as on-line gaming or military training simulations are normally considered to be non-deterministic. Analysis of these simulations is therefore difficult, depending solely on logging and runtime observations. This paper explores an approach for removing one major source of non-determinism in these simulations, thereby allowing repeatable executions. Specifically, we use a synchronization protocol to ensure repeatable delivery of messages. Through limited instrumentation of the simulation code, we maintain a virtual time clock, by which message delivery is governed. The additional overhead imposed by the scheme is shown to be reasonable, although additional reductions in this overhead are anticipated. The results are demonstrated in the context of a simple combat model, whose only source of non-determinism is communications latency. The simulation is shown to be made repeatable, and the perturbation on the execution compared to the non-repeatable execution small. The paper is one step in bridging the gap between the traditional PDES perspective and real-time simulation world.

T. McLean and R. Fujimoto, "Repeatability in Real-Time Distributed Simulation Executions," Proceedings Fourteenth Workshop on Parallel and Distributed Simulation(PADS), Bologna, Italy, 2000, pp. 23.
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