A hypercube algorithm for GVT computation and its application in optimistic parallel simulation

We present an algorithm for computing the global virtual time (GVT) in an optimistic parallel discrete event simulation, on the distributed memory hypercube architecture. Our algorithm uses only 3N messages and runs in O(log N) time where N is the number of logical processors (LP´s) representing components of the simulation system. It is based on the construction of a spanning binomial tree in the hypercube. In most simulation systems, there is an LP designated for GVT computation, called the GVT manager. Failure of the physical processor running this LP causes the simulation process to stop, and in such a case reorganization of LPs is necessary so that another logical processor take the roll of the GVT manager. In our algorithm, any LP in the system can elect itself to be the GVT manager and hence such reorganization is not necessary. We show how our algorithm can be used for memory management and hierarchical load balancing in a hypercube machine, and suggest a new technique to handle transient messages