Fabian Gomes

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SimKit is a C++ class library that is designed for fast discrete event simulation. SimKit presents a simple, elegant logical process view of simulation enabling both sequential and parallel execution without code changes to application models. The sequential executive performs well on a variety of UNIX platforms and facilitates debugging and testing. The(More)
Time Warp's optimistic scheduling requires the maintenance of simulation state history to support rollback in the event of causality violations. State history, and the ability to rollback the simulation, can provide unique functionality for human-in-the-loop simulation environments. This paper investigates the use of Time Warp to output valid simulation(More)
The design of an ATM traffic and network (ATM-TN) simulator which characterizes cell level network behavior is presented. The simulator incorporates three classes of ATM traffic source models: an aggregate ethernet model, an MPEG model and a World Wide Webb transactions model. Six classes of ATM switch architectures are modeled including output buffered,(More)
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(More)
One of the greatest challenges in making optimistic synchronization techniques such as Time Warp practical tools is making state saving efficient and easy to use. State saving is necessary so that when optimistic execution is found to be out of order, rollback can be used to recover an earlier execution state. Previous work has shown that the most robust(More)
Approaches to state saving and rollback for a shared memory, optimistically synchronized, simulation executive are presented. An analysis of copy state saving and incremental state saving is made and these two schemes are compared. Two benchmark programs are then described, one a simple, all overhead, model and one a performance model of a regional Canadian(More)
The use of shared memory computers to implement the TimeWarp algorithm for distributed discrete event simulation is discussed. Actual experience on an implementation for the KSR-1 is described and compared with another implementation on explicit message passing machines. Modifications necessary to achieve good speedup are described. Performance results on(More)
Optimistic parallel discrete event simulation (PDES) uses a state history trail to support rollback. State saving strategies range from making a complete copy of a model’s state after each event execution to recording a sequence of each state modification made during event execution. The former is called copy state saving (CSS) and the latter incremental(More)
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