A great deal of research in the area of distributed discrete event simulation has focussed on evaluating the performance of variants of conservative and optimistic methods on different types of applications. Applicati...
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ISBN:
(纸本)1565550277
A great deal of research in the area of distributed discrete event simulation has focussed on evaluating the performance of variants of conservative and optimistic methods on different types of applications. Application characteristics like lookahead, communication patterns, etc. have been found to affect the suitability of a specific protocol to simulate a given model. For many systems, it may be the case that different subsystems possess contradictory characteristics such that whereas some subsystems may be simulated efficiently using a conservative protocol, others may be more amenable to optimistic methods. Furthermore, the suitability of a protocol for a given subsystem may change dynamically. We propose a parallelsimulation protocol that allows different parts of a system to be simulated using different protocols, allowing these protocols to be switched dynamically. A proof of correctness is presented, along with some preliminary performance discussion.
In distributedsimulations, such as multi-player distributed virtual environments (DVE), power consumption traditionally has not been a major design factor. However, emerging battery-operated mobile computing platform...
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ISBN:
(纸本)0769519709
In distributedsimulations, such as multi-player distributed virtual environments (DVE), power consumption traditionally has not been a major design factor. However, emerging battery-operated mobile computing platforms require revisiting DVE implementation approaches for maximizing power efficiency. In this paper we explore some implications of power considerations in DVE implementation over mobile handhelds connected by wireless networks. We focus on the state dissemination problem in DVEs and propose a new power-aware dead reckoning framework for power-efficient state dissemination. We highlight a fundamental tradeoff between state consistency and power consumption, and present an adaptive dead reckoning algorithm that attempts to dynamically optimize the tradeoff at runtime. We present a quantitative evaluation of our approach using a synthetic DVE benchmark application.
The proceedings contain 69 papers. The topics discussed include: exploiting the parallel divide-and-conquer method to solve the symmetric tridiagonal eigenproblem;biological sequence analysis on distributed-shared mem...
ISBN:
(纸本)0818683325
The proceedings contain 69 papers. The topics discussed include: exploiting the parallel divide-and-conquer method to solve the symmetric tridiagonal eigenproblem;biological sequence analysis on distributed-shared memory multiprocessors;scheduling tasks in DAG to heterogeneous processor system;effective scheduling in a mixed parallel and sequential computing environment;distributed computation in a three-dimensional mesh with communication delays;automatic performance evaluation of parallel programs;architecture-dependent partitioning of dependence graphs;modeling and simulation of integrated modular avionics;improving parallel computer communication: dynamic routing balancing;using channel pipelining in reconfigurable interconnection networks;and exploiting write semantics in implementing partially replicated casual objects.
The proceedings contain 18 papers. The topics discussed include: new approaches to protein functional inference and ligand screening with application to the human kinome;federate fault tolerance in HLA-based simulatio...
ISBN:
(纸本)9781424472918
The proceedings contain 18 papers. The topics discussed include: new approaches to protein functional inference and ligand screening with application to the human kinome;federate fault tolerance in HLA-based simulation;continuous matching algorithm for interest management in distributed virtual environments;a methodology to predict the performance of distributedsimulations;optimizing a business process model by using simulation;selecting simulation algorithm portfolios by genetic algorithms;on validation of semantic composability in data-driven simulation;integrative models of the hepatitis C virus infection: modeling wicked problems;functional level hardware simulation with pull-model data flow;flow: a stream processing system simulator;reversible parallel discrete-event execution of large-scale epidemic outbreak models;validation of radio channel models using an anechoic chamber;and explicit spatial scattering for load balancing in conservatively synchronized parallel discrete-event simulations.
Excessive rollback recoveries due to overoptimistic event execution in Time Warp simulators often degrade their runtime performance. This paper presents a two-sided throttling scheme to dynamically adjust the event ex...
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Excessive rollback recoveries due to overoptimistic event execution in Time Warp simulators often degrade their runtime performance. This paper presents a two-sided throttling scheme to dynamically adjust the event execution speed of Time Warp simulators. The proposed throttle is based on a new concept called global progress window, which allows the individual simulation process to be positioned on a global time scale, thereby to accelerate or suspend their event execution. As each simulation process can be throttled to a steady state, excessive rollback recoveries due to causality errors can be avoided. To quantify the effect of rollbacks and for purpose of comparing different Time Warp implementations, we propose two new measures called RPE (number of Rollback events Per committed Event), and Ε (relative Effectiveness in reducing rollback overhead). Our implementation results show that the proposed throttle effectively regulates the proceeding of each simulation process, resulting in a significant reduction in rollback thrashing and elapsed time.
This paper investigates issues concerning federations of sequential and/or parallel simulators. An approach is proposed for creating federated simulations by defining a global conceptual model of the entire simulation...
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This paper investigates issues concerning federations of sequential and/or parallel simulators. An approach is proposed for creating federated simulations by defining a global conceptual model of the entire simulation, and then mapping individual entities of the conceptual model to implementations within individual federates. Proxy entities are defined as a means for linking entities that are mapped to different federates. Using this approach, an implementation of a federation of optimistic simulators is examined. Issues concerning the adaptation of optimistic simulators to a federated system are discussed. The performance of the federated system utilizing runtime infrastructure (RTI) software executing on a shared memory multiprocessor (SMP) is compared with a native (non-federated) SMP-based optimistic parallel simulator. It is demonstrated that a well designed federated simulation system can yield performance comparable to a native, parallelsimulation engine, but important implementation issues must be properly addressed.
The unthrottled optimism underlying the Time Warp (TW) parallelsimulation protocol can lead to excessive aggressiveness in memory consumption due to saving state histories, and waste of CPU cycles due to overoptimist...
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ISBN:
(纸本)081867931X
The unthrottled optimism underlying the Time Warp (TW) parallelsimulation protocol can lead to excessive aggressiveness in memory consumption due to saving state histories, and waste of CPU cycles due to overoptimistically progressing simulations that eventually have to be ''rolled back''. Furthermore, in TW simulations executing in distributed memory environments, the communication overhead induced by the rollback mechanism can cause pathological overall simulation performance. In this work direct optimism control mechanisms are used to overcome these shortcomings by probabilistically controlling simulation progression based on the forecasted time stamp of forthcoming messages. Several forecast methods are presented and their performance is compared for very large Petri net simulation models executed with the TW protocol on the Meiko CS-2.
Performance models exist that reliably describe the execution time and efficiency of parallel discrete-event simulations executed in a synchronous iterative fashion. These performance models incorporate the effects of...
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Performance models exist that reliably describe the execution time and efficiency of parallel discrete-event simulations executed in a synchronous iterative fashion. These performance models incorporate the effects of processor heterogeneity, other processor load due to shared computational resources, application workload imbalance, and the use of speculative computation. This includes modeling the effects of predictive optimism, a technique for improving the accuracy of speculative assumptions. We extend these models to incorporate correlated workloads across the set of processors and validate the models with two different applications.
In mobile ad hoc network (MANET) studies, it is imperative to use highly detailed device models as they provide high layer protocols with good prediction of underlying wireless communication performance. However, such...
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ISBN:
(纸本)0769521118
In mobile ad hoc network (MANET) studies, it is imperative to use highly detailed device models as they provide high layer protocols with good prediction of underlying wireless communication performance. However, such studies often utilize abstract models for execution speed and simplicity. This paper first shows that physical layer variables including path loss, shadowing, multipath, Doppler have significant effects on the predicted overall networking performance. It then proposes an approach to simulate details of wireless propagation and radio characteristics in networking studies while still maintaining a reasonable simulation execution time. Through our runtime performance studies with detailed OFDM Simulink / MATLAB models and QualNet network simulator, it is shown that the proposed approach can improve the simulation runtime performance by three to four orders of magnitudes without compromising the fidelity of simulation results.
In order to guarantee correctness of simulations, conventional parallel Discrete Event simulation models impose a sequential mode of execution on the events belonging to a logical process (LP). This constraint, which ...
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