Transparent Implementation Of Conservative Algorithms In Parallel Simulation Languages

Parallel discrete event simulation offers significant speedup over the traditional sequential event list algorithm. A number of conservative and optimistic algorithms have been proposed and studied for parallel simulation. We examine the problem of transparent execution of a simulation model using conservative algorithms, and present experimental results on the performance of these transparent implementations. The conservative algorithms implemented and compared include the null message algorithm, the conditional-event algorithm, and a new algorithm which is a combination of these. We describe how dynamic topology can be supported by conservative algorithms. Language constructs to express lookahead are discussed. Finally, performance measurements on a variety of benchmarks are presented, along with a study of the relationship between model characteristics like lookahead, communication topology and the performance of conservative algorithms. 1 INTRODUCTION Distributed(or parallel) simu..

Parallel Hybrid Models in System Design

A parallel hybrid model is a partially implemented design, where some components exist as simulation models and others as operational subsystems, which executes on a parallel 1 architecture. It supports an evolutionary design approach for complex, distributed systems such that an initial simulation model of the proposed design is iteratively refined and elaborated into an implemented system. It also supports hybrid simulation of physical modules and simulation models to facilitate rapid prototyping of complex, distributed systems. The paper describes the use of parallel hybrid models in system design, and discusses their execution issues including cyclic dependency, event causality, and real-time constraints. 1 INTRODUCTION Our research is motivated by the following two observations. (1) Design Methodology. The conventional big bang approach to designing complex, time-critical distributed systems usually consists of the following three steps: (a) given the specifications, construct..

Path Lookahead: a Data Flow View of PDES Models

The performance of parallel discrete event simulation protocols is heavily dependent on the lookahead of the simulation model. Identifying and expressing correct lookahead for a model isn't easy, nor is it a well-defined process. In this paper, a global view of a PDES model as a set of data flows is presented. Using this view, we show how the lookahead of the model can be optimized, and we present various simplified implementations of this global view and the significant performance improvements generated when applied to real world models. 1 Introduction The complexity of many modern systems, ranging from wireless networking, internetworking, wargaming, to computer architecture design, defies analytical modeling techniques. A scalable simulation environment, with features such as object aggregation, varying levels of abstraction, and parallel model execution, is necessary to model these systems. Further, in some of these domains, there is a distinct need for real-time responsiveness..

Building Parallel Time-Constrained HLA Federates: A Case Study with the PARSEC Parallel Simulation Language

International audienceBased on the DIS result, the HLA framework has been defined to achieve interoperability of independent simulators. Concurrently, and for the most part, independent of that effort, the parallel and distributed simulation community has attempted to define synchronization protocols for the correct execution of parallel simulation as-fast-as possible. Building parallel time-constrained federates within an HLA framework is not an easy task. We identify the potential difficulties: one or several federates, when and how to advance the federate's time, how to handle RTI notifications, etc., and present our experiences with adding HLA features into the PARSEC parallel simulation language

HLA Support in a Discrete Event Simulation Language

International audienceThere has been a growing interest in the HLA proposal as a common framework for real-time, distributed and interactive simulations. Although most of HLA compliant federates are for the moment developed with general purpose languages, the development of HLA federates with an existing simulation language would enable the rapid porting of a large number of existing simulations into the HLA framework. The difficulties of supporting the HLA features in a discrete event simulation language come from the different way the two approaches manage the simulation time and the interactions between objects in the simulation. This paper addresses these problems and uses the PARSEC discrete event simulation language as a test case. \textcopyright 1999 IEEE

Improving Lookahead in Parallel Wireless Network Simulation.

Simulation of large sets of mobile computers or other wireless communication devices is difficult because of the computationally intensive models of wireless channels. Parallel simulation would seem to be applicable here because of the large computation granularity, but the location based communication topology makes conservative methods difficult to implement. This paper considers a novel approach to improving lookahead in conservative parallel simulations by differentiating between data flow paths in the simulation. An experimental study shows that for this application, the technique produces a 70% reduction in null message traffic, with only a 25% increase in null message computation overhead, and a consistent improvement in parallel performance. 1 Introduction The exploding demand for nomadic computing and communication has led to significant interest in the design of large wireless, mobile systems. This in turn has resulted in a number of new protocols for wireless networks that ..