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 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.
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-...
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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.
We present two GVT computation algorithms for PDES techniques with event based activities, and relying on a space-time memory abstraction. Algorithm 2 involves a modification in the activity control, and is based on a...
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We present two GVT computation algorithms for PDES techniques with event based activities, and relying on a space-time memory abstraction. Algorithm 2 involves a modification in the activity control, and is based on an epoch coloring scheme. The effect of the modification is assessed through an experimental study on a simulator implemented in the Linda coordination language. Experiments are performed on a cluster of workstations, and show that the modified activity control discipline is able to enhance performances.
This paper describes a new, auto-adaptive algorithm for dead reckoning in DIS. In general dead-reckoning algorithms use a fixed threshold to control the extrapolation errors. Since a fixed threshold cannot adequately ...
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This paper describes a new, auto-adaptive algorithm for dead reckoning in DIS. In general dead-reckoning algorithms use a fixed threshold to control the extrapolation errors. Since a fixed threshold cannot adequately handle the dynamic relationships between moving entities, a multi-level threshold scheme is proposed. The definition of threshold levels is based on the concepts of area of interest (AOI) and sensitive region (SR), and the levels of threshold are adaptively adjusted based on the relative distance between entities during the simulation. Various experiments were conducted. The results show that the proposed auto-adaptive dead reckoning algorithm can achieve considerable reduction in update packets without sacrificing accuracy in extrapolation.
This paper presents the SEEDS simulation environment for the evaluation of distributed traffic control systems. Starting with an overview of the general simulator architecture, the software modules and the derived har...
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This paper presents the SEEDS simulation environment for the evaluation of distributed traffic control systems. Starting with an overview of the general simulator architecture, the software modules and the derived hardware architecture of the simulation environment are described with respect to performance requirements. The communication architecture of the SEEDS simulator is based on the OMG's CORBA standard and the DIS simulation protocol. With the SEEDS prototype simulating airport ground-traffic, performance measurements evaluating critical design and implementation decisions are described. The main aspects of the performance analysis are the attained application performance using CORBA and DIS as communication middle-ware, and the scalability of the overall approach. The evaluation shows the appropriateness of the design of the simulation environment and the derived hard- and software architecture, which is flexible and open to further extensions. Moreover, the combination of CORBA and DIS provides a suited platform for distributed interactive simulation purposes because of the adequate performance, high scalability, and the high-level programming model which allows to rapidly develop and maintain complex distributed applications with high-performance requirements.
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