A Fast Asynchronous GVT Algorithm for Shared Memory Multiprocessor Architectures.

Z. Xiao, F. Gomes, B. Unger and J. Cleary. Proceedings of the 1995 Workshop on Parallel and Distributed Simulation (PADS95), Lake Placid, New York, June 14-16, 1995.

Abstract: The computation of Global Virtual Time is of fundamental importance in Time Warp based Parallel Discrete Event Simulation Systems. Shared memory multiprocessor architectures can support interprocess communication with much smaller overheads than distributed memory systems. This paper presents a new, completely asynchronous, GVT algorithm which provides very fast and accurate GVT estimation with significantly lower overhead than previous approaches. The algorithm presented is able to support more efficient memory management, termination, and other global control mechanisms.

The GVT algorithm described enables any Time Warp entity to compute GVT at any time without slowing down other entities, in particular, those executing on the critical path. Experimental results are presented for a shared memory Time Warp system that employs a two tiered distributed memory management scheme.

The proof of the correctness and the accuracy of the algorithm are also presented. Finally, some suggestions on possible further optimization of the implementation are given.