The paper describes Nops, a conservatively synchronized process oriented parallelsimulation system. Nops is designed to support the programming model of the Telecommunications Description Language (TeD), with special...
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The paper describes Nops, a conservatively synchronized process oriented parallelsimulation system. Nops is designed to support the programming model of the Telecommunications Description Language (TeD), with special emphasis on scaling up to very large network models. We chronicle the decisions beyond Nops' design, describe that design, assess its raw performance relative to CSIM, Maisie, and GTW, and study its ability to scale to large models.
One of the key factors for efficiency in distributedsimulation is the detection of model-inherent concurrency, which is related on the prediction of the future behavior of each logical simulation process. We present ...
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One of the key factors for efficiency in distributedsimulation is the detection of model-inherent concurrency, which is related on the prediction of the future behavior of each logical simulation process. We present a generalization of traditional approaches to behavioral prediction which provides more accurate predictions in general and a high degree of scalability in terms of computational and communication overhead. We give a sequential implementation, prove its correctness using concepts from the analysis of real time process networks and then show how these results can be used in distributedsimulation.
One of the main reasons why parallel discrete event simulation has not been adopted more widely in industry is that the terminology used by the parallelsimulation community differs from that of industrial simulation ...
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One of the main reasons why parallel discrete event simulation has not been adopted more widely in industry is that the terminology used by the parallelsimulation community differs from that of industrial simulation practitioners. The paper shows how the gap between these two communities can be bridged by presenting a methodology for automating the parallelization of manufacturing simulations. Our approach provides a way of automatically generating a mapping from a sequential simulation model to an efficient parallel implementation. The results of this mapping can be expressed in a form which is independent of any particular parallelsimulation system or language. Since it is easy to generate code for different simulation systems, it is possible to evaluate alternative parallelsimulation protocols at an early stage of development. A prediction of the performance can thus be obtained by studying the behaviour of an abstraction of the simulation model with various strategies or on different computing platforms.
Circuit simulation is a critical bottleneck in VLSI design. The paper describes the implementation of an existing parallel switch level simulator called MIR-SIM on a shared memory multiprocessor architecture. The simu...
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Circuit simulation is a critical bottleneck in VLSI design. The paper describes the implementation of an existing parallel switch level simulator called MIR-SIM on a shared memory multiprocessor architecture. The simulator uses a set of three different conservative protocols: the null message protocol; the conditional event protocol and the accelerated null message protocol; and combinations of the preceding two algorithms. The paper describes the implementation of these protocols to exploit shared memory features, measures their relative performance for a set of six benchmark circuits ranging in size from 3000 to almost 70000 transistors, and compares the speedup obtained by each of the three protocols.
The implementation of a cloning mechanism that allows for the evaluation of multiple simulated futures is presented and its performance is analyzed. A running parallel discrete event simulation is dynamically cloned a...
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The implementation of a cloning mechanism that allows for the evaluation of multiple simulated futures is presented and its performance is analyzed. A running parallel discrete event simulation is dynamically cloned at decision points to explore different execution paths concurrently. In this way, what-if and alternative scenario analysis in gaming, tactical and strategic applications can be evaluated interactively or non-interactively. Performance results show that virtual logical processes, a new mechanism developed to avoid repeating common computations among clones improves efficiency.
The simulation of wireless systems such as cellular or personal communication systems comprises both discrete and continuous time processes. To accelerate these simulations, we propose the use of interval jumping, a n...
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The simulation of wireless systems such as cellular or personal communication systems comprises both discrete and continuous time processes. To accelerate these simulations, we propose the use of interval jumping, a novel technique that allows the execution of a continuous time model to proceed in irregularly sized jumps, rather than in the traditional time-stepped manner. The foundations for this mechanism are laid out in the light of the simulation of a complex simulation model which includes radio propagation, channel allocation, transmitter power control and user mobility. We conclude with experimental results comparing sequential and parallel execution of these accelerated simulations which indicate the potential of our technique.
The paper presents a sparse state saving scheme for Time Warp parallel discrete event simulation. The scheme bases the selection of the states to be recorded on the event history of the logical processes. To this purp...
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The paper presents a sparse state saving scheme for Time Warp parallel discrete event simulation. The scheme bases the selection of the states to be recorded on the event history of the logical processes. To this purpose, statistics on the virtual time advancement of the processes are collected for the prediction of virtual time intervals that are likely to contain rollback points; the states corresponding to the starting point of those intervals are recorded as checkpoints in order to reduce the average coasting forward. The percentage of states to be recorded is defined by a parameter whose value is dynamically recalculated on the basis of the online observation of the variation of a checkpointing rollback cost function. simulation results of synthetic workloads are presented for a performance comparison with previous schemes.
We describe the TED/C++ implementation of WIPPET, a parallelsimulation testbed for evaluating radio resource management algorithms and wireless transport protocols. Versions 0.3 and 0.4 of the testbed model radio pro...
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We describe the TED/C++ implementation of WIPPET, a parallelsimulation testbed for evaluating radio resource management algorithms and wireless transport protocols. Versions 0.3 and 0.4 of the testbed model radio propagation (long- and short-scale fading and interference) and protocols for integrated radio resource management in mobile wireless voice networks including the standards based AMPS, NA-TDMA and GSM protocols, and several research oriented protocol families. We provide parallel performance data verifying that the dominant computational demand due to received signal quality calculation can be partitioned geographically by orthogonal radio channels, or in a hybrid manner.
With the emerging of broadband networks based on ATM technology, performance evaluation tools that allow the study of large systems are desperately needed. We present our experiments in distributedsimulation of large...
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With the emerging of broadband networks based on ATM technology, performance evaluation tools that allow the study of large systems are desperately needed. We present our experiments in distributedsimulation of large and complex ATM network models with a conservative simulator. The goal here was not to achieve the maximum speedup with well shaped topologies bat rather to see what speedup can be obtained with a realistic model on a "state of the art" parallel computer. A network model with 78 switches is simulated on a Cray T3E using 3 different traffic loads. The performance results show that good speedups can be achieved but they also highlight partitioning problems and bottlenecks in the simulation model that can seriously limit the speedup of realistic model simulations.
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