The proliferation of mobile devices and the fact that high-bandwidth and continuous connectivity is not available everywhere, has led to the creation of hoarding algorithms that attempt to mitigate the problems relate...
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ISBN:
(纸本)159593488X
The proliferation of mobile devices and the fact that high-bandwidth and continuous connectivity is not available everywhere, has led to the creation of hoarding algorithms that attempt to mitigate the problems related with disconnected operation and with the operation in areas where bandwidth is either scarce or expensive. In this paper, we present a hoarding scheme for location-based data in semi-structured information spaces, such as the World Wide Web, which relies on clustering of semantically related data items. We show by means of experimental evaluation that our clustering-based approach outperforms existing hoarding techniques that do not make use of clustering by a factor of more than 2 in terms of hoard cache hit ratio. Copyright 2006 ACM.
Copyright and Reprint Permissions: Abstracting is permitted with credit to the source. Libraries may photocopy beyond the limits of US copyright law, for private use of patrons, those articles in this volume that carr...
Copyright and Reprint Permissions: Abstracting is permitted with credit to the source. Libraries may photocopy beyond the limits of US copyright law, for private use of patrons, those articles in this volume that carry a code at the bottom of the first page, provided that the per-copy fee indicated in the code is paid through the Copyright Clearance Center. The papers in this book comprise the proceedings of the meeting mentioned on the cover and title page. They reflect the authors' opinions and, in the interests of timely dissemination, are published as presented and without change. Their inclusion in this publication does not necessarily constitute endorsement by the editors or the Institute of Electrical and Electronics Engineers, Inc.
Monte Carlo is a powerful and versatile derivative pricing tool, with the main drawback of requiring a large amount of computing time to generate enough realisations of the stochastic process. However, since realisati...
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parallel and distributedsimulations enable the analysis of complex systems by concurrently exploiting the aggregate computation power and memory of clusters of execution units. In this paper we investigate a new dire...
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ISBN:
(纸本)0769523838
parallel and distributedsimulations enable the analysis of complex systems by concurrently exploiting the aggregate computation power and memory of clusters of execution units. In this paper we investigate a new direction for increasing both the speedup of a simulation process and the utilization Of computation and communication resources. Many simulation-based investigations require to collect independent observations for a correct and significant statistical analysis of results. The execution of many independent parallel or distributedsimulation runs may suffer the speedup reduction due to rollbacks under the optimistic approach, and due to idle CPU times originated by synchronization and communication bottlenecks under the conservative approach. We present a parallel and distributedsimulation framework supporting Concurrent Replication of parallel and distributedsimulations (CR-PADS), as an alternative to the execution of a linear sequence of multiple parallel or distributedsimulation runs. Results obtained from tests executed under variable scenarios show that speedup and resource utilization gains could be obtained by adopting the proposed replication approach in addition to the pure parallel and distributedsimulation.
A novel micro-kernel approach to building parallel/distributedsimulation systems is presented. Using this approach, a unified system architecture is developed for incorporating, multiple types of simulation processes...
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ISBN:
(纸本)0769523838
A novel micro-kernel approach to building parallel/distributedsimulation systems is presented. Using this approach, a unified system architecture is developed for incorporating, multiple types of simulation processes. The processes hold potential to employ a variety of synchronization mechanisms, and could even alter their choice of mechanism dynamically. Supported mechanisms include traditional lookahead-based conservative and state saving-based optimistic execution approaches. Also supported are newer mechanisms such as reverse computation-based optimistic execution and aggregation-based event processing, all within a single parsimonious application programming interface. The internal implementation and a preliminary performance evaluation of this interface are presented in mu sik, which is an efficient parallel/distributed realization of the microkernel architecture in C++.
Neural systems are composed of a large number of highly-connected neurons and are widely simulated within the neurological community. In this paper, we examine the application of parallel discrete event simulation tec...
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ISBN:
(纸本)0769523838
Neural systems are composed of a large number of highly-connected neurons and are widely simulated within the neurological community. In this paper, we examine the application of parallel discrete event simulation techniques to networks of a complex model called the Hodgkin-Huxley neuron[1]. We describe the conversion of this model into an event-driven simulation, a technique that offers the potential of much greater performance in parallel and distributedsimulations compared to time-stepped techniques. We report results of an initial set of experiments conducted to determine the feasibility of this parallel event-driven Hodgkin-Huxley model and analyze its viability for large-scale neural simulations.
As an alternative to spatial parallelization of simulation models, time-parallelsimulation offers the potential for massive parallelism with a high level of independence between the parallel processes. Unfortunately,...
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ISBN:
(纸本)0769523838
As an alternative to spatial parallelization of simulation models, time-parallelsimulation offers the potential for massive parallelism with a high level of independence between the parallel processes. Unfortunately, due to inherent problems, the applicability of time-parallelsimulation is restricted. Therefore, it has been proposed recently, to use approximation with time-parallelsimulation in order to facilitate its application and to extend the class of models suitable for time-parallelsimulation. As a proof-of-concept, this work shows how approximate temporal parallelization can be applied to the simulation of road traffic. Traffic simulation is used extensively in transportation research for various purposes, e.g. analysis of traffic phenomena, traffic forecast, and optimization of traffic flow. Depending on the level of fidelity, a traffic model exhibits a state space of moderate to high complexity. This paper is intended to discuss the basic properties of time-parallel traffic simulation and to examine its feasibility. Experiments with a sequential microscopic traffic simulator that emulates important aspects of a corresponding time-parallel simulator suggest this feasibility.
The widespread use of sequential simulation in large scale parameter studies means that large cost savings can be made by improving the performance of these simulators. Sequential discrete event simulation systems usu...
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ISBN:
(纸本)0769523838
The widespread use of sequential simulation in large scale parameter studies means that large cost savings can be made by improving the performance of these simulators. Sequential discrete event simulation systems usually employ a central event list to manage future events. This is a priority queue ordered by event timestamps. Many different priority queue algorithms have been developed with the aim of improving simulator performance. Researchers developing asynchronous conservative parallel discrete event simulations have reported exceptional performance for their systems running sequentially in certain cases. This paper compares the performance of simulations using a selection of high performance central event list implementations to that achieved using techniques borrowed from the parallelsimulation community. Theoretical and empirical analysis of the algorithms is presented demonstrating the range of performance that can be achieved, and the benefits of employing parallelsimulation techniques in a sequential execution environment.
The proceedings contain 30 papers from the workshop on Principles of Advanced and distributedsimulation, PADS 2005. The topics discussed include: modeling and simulating the brain as a system;towards time-parallel ro...
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The proceedings contain 30 papers from the workshop on Principles of Advanced and distributedsimulation, PADS 2005. The topics discussed include: modeling and simulating the brain as a system;towards time-parallel road traffic simulation;parallel event-driven neural network simulations using the Hodgkin-Huxley Neuron model;optimistic protocol analysis in a performance analyzer and prediction tool;distributed worm simulation with a realistic internet model;mobile contagion: simulation of infection and defense;efficient simulation of Wireless Networks Using Lazy MAC state update;the WarpIV simulation kernel;preliminary simulation of the effect of scanning worm activity on multicast;and merging parallelsimulation programs.
parallel discrete event simulation (PDES) of models with fine-grained computation remains a challenging problem. We explore the usage of POSE, our parallel Object-oriented simulation Environment, for application perfo...
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ISBN:
(纸本)0769523838
parallel discrete event simulation (PDES) of models with fine-grained computation remains a challenging problem. We explore the usage of POSE, our parallel Object-oriented simulation Environment, for application performance prediction on large parallel machines such as BlueGene. This study involves the simulation of communication at the packet level through a detailed network model. This presents an extremely fine-grained simulation: events correspond to the transmission and receipt of packets. Computation is minimal, communication dominates, and strong dependencies between events result in a low degree of parallelism. There is limited look-ahead capability since the outcome of many events is determined by the application whose performance the simulation is predicting. Thus conservative synchronization approaches are challenging for this type of problem. We present recent experiences and performance results for our network simulator and illustrate the utility of our simulator through prediction and validation studies for a molecular dynamics application.(1)
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