simulation of particle systems is time consuming. However, many particle system applications require fast interactive animations. For example, simulation of physically realistic complex dust behaviors is very useful i...
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Virtual spaces based on the metaphor of shared network places are becoming a well accepted implementation approach for multiuser, multimedia, distributed cooperative work environments to support the work activities an...
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Traditionally, parallel discrete-event simulators based on the Time Warp synchronization protocol have been implemented using either the shared memory programming model or the distributed memory, message passing progr...
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Traditionally, parallel discrete-event simulators based on the Time Warp synchronization protocol have been implemented using either the shared memory programming model or the distributed memory, message passing programming model. This was because the preferred hardware platform was either a shared memory multiprocessor workstation or a network of uniprocessor workstations. However, with the advent of clumps (cluster of shared memory multiprocessors), a change in this dichotomous view becomes necessary. This paper explores the design and implementation issues involved in exploiting this new platform for Time Warp simulations. Specifically, this paper presents two generic strategies for implementing Time Warp simulators on clumps. In addition, we present our experiences in implementing these strategies on an extant distributed memory, message passing Time Warp simulator (WARPED). Preliminary performance results comparing the modified clump-specific simulation kernel to the unmodified distributed memory, message passing simulation kernel are also presented.
Most successful examples of parallelsimulation models were developed for parallel execution, from the beginning. A number of simulation models are designed only for sequential simulation, even in languages like PARSE...
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Most successful examples of parallelsimulation models were developed for parallel execution, from the beginning. A number of simulation models are designed only for sequential simulation, even in languages like PARSEC, that support both sequential and parallelsimulation algorithms. Converting such simulation models to a form that yields good performance with a parallel implementation can be non-trivial. In this paper we describe a case study showing this conversion process for a simulation model of replicated file systems. The details of the major steps taken in converting the simulation into a parallelsimulation are presented: correctness changes;performance changes such as communication topology simplification and lookahead specification;and modeling changes to eliminate performance bottlenecks. The details and performance improvements of each step are presented in this paper.
The article addresses a problem of optimal query processing in heterogeneous and distributed multidatabase systems. The objective is to find a method for optimization of global query processing plans. Two generic stra...
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The article addresses a problem of optimal query processing in heterogeneous and distributed multidatabase systems. The objective is to find a method for optimization of global query processing plans. Two generic strategies of query processing in heterogeneous and distributed systems include entirely sequential and entirely parallel approaches. The paper describes a hybrid strategy where some of the subqueries are submitted and processed sequentially while the others are processed in parallel. Optimization of query postprocessing is proposed and described in order to reduce an impact of errors in estimation of processing costs at the local systems.
The Scalable simulation Framework (SSF) is an effort established to address the concern about tool quality. This work addresses the concern over unpredictable behavior. It is shown how the internal overheads of the Da...
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The Scalable simulation Framework (SSF) is an effort established to address the concern about tool quality. This work addresses the concern over unpredictable behavior. It is shown how the internal overheads of the Dartmouth implementation of the SSF API (DaSSF) have been measured, and how such measurements can be used to predict the performance of a given model, using given features of the simulator, without having to run, or even build, the model.
The High Level Architecture (HLA) provides the specification of a software architecture for distributedsimulation. The baseline definition of the HLA includes the HLA Rules, The HLA Interface Specification, and the H...
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The High Level Architecture (HLA) provides the specification of a software architecture for distributedsimulation. The baseline definition of the HLA includes the HLA Rules, The HLA Interface Specification, and the HLA Object Model Template. The HLA Rules are a set of 10 basic rules that define the responsibilities and relationships among the components of an HLA federation. The HLA Interface Specification provides a specification of the functional interfaces between HLA federates and the HLA Runtime Infrastructure. The HLA OMT provides a common presentation format for HLA simulation and Federation Object Models. The HLA was developed over the past three years. It is currently in the process of being applied with simulations developed for analysis, training and test and evaluation and incorporated into industry standards for distributedsimulation by both the Object Management Group and the IEEE. This paper provides a discussion of key areas where there are technology challenges in the future implementation and application of the HLA.
In this paper, we present a parallel simulator (SWiMNet) for PCS networks using a combination of optimistic and conservative paradigms. The proposed methodology exploits event precomputation permitted by model indepen...
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In this paper, we present a parallel simulator (SWiMNet) for PCS networks using a combination of optimistic and conservative paradigms. The proposed methodology exploits event precomputation permitted by model independence within the PCS components. The low percentage of blocked calls is exploited in the channel allocation simulation of precomputed events by means of an optimistic approach. Experiments were conducted with various call arrival rates and mobile host densities on a cluster of Pentium workstations. Performance results indicate that the SWiMNet achieves a speedup of 6 employing 8 workstations, and a speedup of 12 with 16 workstations.
Environment aware, self adaptive Time Warp logical processes (LPs) implementing a pro-active performance control scheme, thus addressing the timeliness of control decisions, are introduced. The ability of these pro-ac...
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Environment aware, self adaptive Time Warp logical processes (LPs) implementing a pro-active performance control scheme, thus addressing the timeliness of control decisions, are introduced. The ability of these pro-active TW LPs to adapt to sudden load changes is examined. Experimental results show that the protocol is able to capture abrupt changes in both computational and communication resource availability.
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