distributed memory, message passing (DMMP) parallel architectures, such as the intel iPSC(R) computer system, provide the processing power and memory to solve very large parallel programming problems. However, their l...
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distributed memory, message passing (DMMP) parallel architectures, such as the intel iPSC(R) computer system, provide the processing power and memory to solve very large parallel programming problems. However, their large grain process model and distributed memory complicate the programmer's view of the system. Extensions have been created for interwork II's global object name space in order to support arrays of objects;interwork II distributes the element objects among the processing nodes so as to balance the number on each node. Indexed objects simplify the programmer's view of parallel architectures by enabling related data to be automatically partitioned among the processing nodes. They also speedup computations by allowing these data to be operated on in parallel. This mechanism has proved useful as the basis for constructing a large, parallelsimulation.
With two examples we show the suitability of the bulk-synchronous parallel (BSP) model for discrete-event simulation of homogeneous large-scale systems. This model provides a unifying approach for general purpose para...
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ISBN:
(纸本)9780818679650
With two examples we show the suitability of the bulk-synchronous parallel (BSP) model for discrete-event simulation of homogeneous large-scale systems. This model provides a unifying approach for general purpose parallel computing which in addition to efficient and scalable computation, ensures portability across different parallel architectures. A valuable feature of this approach is a simple cost model that enables precise performance prediction of BSP algorithms. We show both theoretically and empirically that systems with uniform event occurrence among their components, such as colliding hard-spheres and ising-spin models, can be efficiently simulated in practice on current parallel computers supporting the BSP model.
The partitioning of systems for parallelsimulation is a complex task, requiring consideration of both computational load requirements and communications activity. Typically, this information is not accurately known p...
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ISBN:
(纸本)9780818671203
The partitioning of systems for parallelsimulation is a complex task, requiring consideration of both computational load requirements and communications activity. Typically, this information is not accurately known prior to execution. This paper investigates the use of historical information for the prediction of future requirements, both for computation and communications. In addition, for optimistic simulation algorithms, we present a novel technique (which we call predictive optimism) whereby binary prediction schemes can be used to increase the accuracy of optimistic assumptions, thereby decreasing rollbacks and potentially improving overall simulator performance.
In a distributedsimulation, simulation components of various types are executed at geographically different locations, forming a simulation federation to create a common virtual environment. Under the High Level Arch...
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ISBN:
(纸本)9780769511047
In a distributedsimulation, simulation components of various types are executed at geographically different locations, forming a simulation federation to create a common virtual environment. Under the High Level Architecture (HLA), information that will be produced and consumed by a simulation component is defined in its object model, and how that information is produced and consumed is well encapsulated inside the simulation component's implementation. However, in the current implementation of the HLA's Runtime Infrastructure (RTI), information hiding between groups of simulation components in a simulation federation is not addressed. In this paper, we discuss how hierarchical federations architectures can be used to tackle this problem. The hierarchical federations architecture adopted in this paper differs from the existing architectures in that it is based on a hybrid approach for inter-operability between simulation federations. To demonstrate the information hiding using the architecture, a distributed semiconductor supply-chain simulation is also described in the paper.
While the PADS community has traditionally focused on—and done a greater job with—the technical aspects of developing simulations that run fast and can be connected to other simulations, it has paid little or no att...
ISBN:
(纸本)9780769506678
While the PADS community has traditionally focused on—and done a greater job with—the technical aspects of developing simulations that run fast and can be connected to other simulations, it has paid little or no attention to the overall strategies required to produce a marketable, useful, and successful parallelsimulation. This lack of market focus has led to many fears of the demise of the PADS community, complaints of its lack of general acceptance by the broader simulation community, and predictions that it will become merely another venue for simulation *** fears, complaints, and predictions are unnecessary. There are several examples of successful parallelsimulations—in domains as far apart as aviation modeling and wargames. What can we learn from their successes? How can we translate their general acceptance into other parallelsimulation domains? Are there market opportunities that we are missing? In short, what is the parallelsimulation community lacking, and what does it need to do in order to be more successful?The purpose of this talk is to begin a discussion on the answers to these questions (as opposed to definitively answering them). We will draw on numerous examples of successful applications, and make some concrete suggestions for furthering the community.
In this paper we discuss and compare three differentcausality inconsistency tracking mechanisms in support ofpreemptive rollback in optimistic parallelsimulation onmyrinet clusters. These mechanisms exhibit different...
ISBN:
(纸本)9780769518534
In this paper we discuss and compare three differentcausality inconsistency tracking mechanisms in support ofpreemptive rollback in optimistic parallelsimulation onmyrinet clusters. These mechanisms exhibit different communication/processing overhead and also different effectivenessin revealing causality inconsistency of the currentlyexecuted simulation event. By the results of an empiricalstudy on a classical simulation benchmark we have foundsome trade-offs between these mechanisms, pointing out indicationsof application contexts for which each mechanismis expected to be well tailored.
A technique called updateable simulations is proposed to reduce the time to complete multiple executions of a discrete event simulation program. This technique updates the results of a prior simulation run rather than...
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ISBN:
(纸本)9780769516080
A technique called updateable simulations is proposed to reduce the time to complete multiple executions of a discrete event simulation program. This technique updates the results of a prior simulation run rather than re-execute the entire simulation to take into account variations in the underlying simulation model. A framework for creating updateable simulations is presented. This framework is applied to the problem of simulating a set of cascaded ATM multiplexers and a network of ATM switches. Performance measurements of sequential and parallel implementations of these simulations on a shared memory multiprocessor are presented, demonstrating that updateable simulations can yield substantial reductions in the time required to complete multiple simulation runs if there is much similarity among the runs.
distributedsimulation enables participants situated in different geographical locations to share a common virtual world, which is called a distributed virtual environment (DVE). Among the different research topics co...
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ISBN:
(纸本)9780769520360
distributedsimulation enables participants situated in different geographical locations to share a common virtual world, which is called a distributed virtual environment (DVE). Among the different research topics concerned with DVE, there is a current trend of linking multi-agent systems and DVE together. With the properties of autonomy, social ability, reactivity and proactiveness, agents can be used to represent entities in DVE, where fast and accurate decision making is a determining factor of the whole environment. This paper provides a description of integrating agents into an HLA-based distributedsimulation. It focuses on how to construct the sensor of an agent with different interest management schemes. Using the JADE (Java agent development framework) agent toolkit and the high level architecture (HLA) in our prototype, a minesweeping game, we outline two different implementations of this game. Due to the dynamic characteristics of agents, a problem of overdue information from the environment is discussed, and we propose an enlarged subscription region method to solve this problem. Moreover, advisories provided by the HLA are adopted to reduce the overheads. Conclusions are drawn based on the experimental results of these implementations.
Rapid growth in wireless communication systems motivates the development of technology supporting the simulation of large-scale wireless systems. However, it is widely recognized that wireless communications do not ha...
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ISBN:
(纸本)9780769516080
Rapid growth in wireless communication systems motivates the development of technology supporting the simulation of large-scale wireless systems. However, it is widely recognized that wireless communications do not have substantial "lookahead" needed by conservative synchronization protocols. This paper focuses on identifying and exploiting lookahead for such models. We find lookahead in three ways, exploiting characteristics of low power networks, the transceiver logic, and the way in which protocol stacks are typically constructed. We show how these observations allow a variety of conservative synchronization protocols to take advantage of lookahead, describe a synchronization method we use, and empirically examine the performance this method offers on a large-scale simulation of a sensor network intended for homeland defense scenarios
We describe a novel approach to scalability and efficiency of parallel network simulation that partitions the networks into domains and simulation time into intervals. Each domain is simulated independently of and con...
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ISBN:
(纸本)9780769516080
We describe a novel approach to scalability and efficiency of parallel network simulation that partitions the networks into domains and simulation time into intervals. Each domain is simulated independently of and concurrently with the others over the same simulation time interval. At the end of each interval, packet delays and drop rates for each inter-domain flow are exchanged between domain simulators. The simulators iterate over the same time interval until the exchanged information converges to a constant value within the prescribed precision. After convergence, all the domain simulators progress to the next time interval. This approach allows the parallelization with infrequent *** biggest challenge for this method is to ensure iteration convergence for protocols, such as TCP, that adjust source rate to the current network conditions. The main contribution of this paper is to demonstrate that by judicious design of the domain processing and information exchange, the proposed approach efficiently parallelizes network simulation with TCP flows.
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