| This dissertation proposes a distributed simulation methodology that unifies the different aspects of the distributed simulation problem for discrete event models: model specification, synchronization and intercommunication, and distributed simulator design. The methodology proceeds as follows: first, the model is specified using a hierarchical modular formalism called Extended DEVS, second, this specification is transformed into a logical form called the abstract simulator, third, synchronization and intercommunication schema are applied to the abstract simulator and last, the resulting abstract simulator is mapped onto the hardware/software architecture. In the Extended DEVS, generic components are introduced to explicitly model timing, delay, and collection/distribution of input/output events. Algorithms are presented for both top-down and bottom-up model construction in this formalism and rules are presented for the transformation of the constructed model into the abstract simulator. The resulting structure is a hierarchy of coordinating processors (coordinators) with the simulators as leaves. The processors are modular and communication is done by message passing, where messages contain control signals for synchronization and input/output data. In this structure, the worst case delay due to synchronization is 0(dlog(,d)S) and that due to intercommunication is 0(log(,d)S) where d is the maximum branching of the hierarchy and S is the number of simulators. The deficit degree of parallelism in the execution of tasks is bounded above by 0(dlog(,d)S).;Finally, we propose a new logical design of a computer architecture, the Hierarchical Multi-Bus Multiprocessor Architecture (HM('2)A). Since the architecture design evolved from the sequence of steps of the methodology, it contains features closely reflecting the structure, behavior and modularity of the model components, and incorporates the synchronization and intercommunication properties of the abstract simulator. This approach improves on previous approaches since the architecture is designed to fit the model rather than the model being imposed on the architecture. |
