Performance analysis of distributed systems may be performed on different levels of abstraction. An accurate but time-consuming method is the construction of a simulation model which includes the different subsystems,...
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ISBN:
(纸本)0818680970
Performance analysis of distributed systems may be performed on different levels of abstraction. An accurate but time-consuming method is the construction of a simulation model which includes the different subsystems, the communication system, and the load profile. In particular, this approach seems to be very powerful for real-time systems because of the inherent possibility of precise calculations of delays and processing times. A VHDL-based approach is presented which supports the performance analysis of mixed discrete-continuous, distributed systems.
In this paper we address the problem of efficiently performing parallel discrete-event simulation in the case that events elaboration is dependent of other processes' local states. We propose a parallelsimulation...
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ISBN:
(纸本)0818679654
In this paper we address the problem of efficiently performing parallel discrete-event simulation in the case that events elaboration is dependent of other processes' local states. We propose a parallelsimulation policy, called State Query Time Warp (SQTW), based on the Time Warp mechanism. We present experiments performed by means of a SQTW-based parallel simulator on a T-800 transputer machine for solving performance models based on state-dependent routing queueing network models. The experiments are used for assessing overheads and efficiency involved by SQTW;results show that high efficiency is achievable, and surprisingly reveal SQTW is able to globally reduce rollback overheads with respect to corresponding Time Warp simulations.
In this paper we revisit the notion of event simultaneity in the context of parallel and distributedsimulation. Although the simulation community has recognized this problem for years, it has focused mainly on the me...
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In this paper we revisit the notion of event simultaneity in the context of parallel and distributedsimulation. Although the simulation community has recognized this problem for years, it has focused mainly on the mechanics of breaking event-time ties and has neither measured its extent nor considered its implications. Extant simulators (both serial and parallel) prohibit simultaneity either by user-specified event priorities or by an arbitrary (but well-documented) tie-breaking mechanism. We shall show, theoretically and empirically, that these strategies may lead to an invalid simulation. In doing so, we shall introduce the threshold of event simultaneity and use it to understand the semantics of simultaneity.
The Hierarchical Tool HIT is a software tool for hierarchical modeling and performance evaluation of discrete event systems. Besides analytical and numerical solution techniques HIT provides the evaluation of models b...
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ISBN:
(纸本)0818679654
The Hierarchical Tool HIT is a software tool for hierarchical modeling and performance evaluation of discrete event systems. Besides analytical and numerical solution techniques HIT provides the evaluation of models by sequential simulation. Here we present concepts for optimistic distributedsimulation of HIT-models by partitioning them with respect to subhierarchies. The main goals of the concept being presented are the preservation of model structure even in lower levels of the realization (e.g. use of the process view of simulation throughout all levels of abstraction) and distribution transparency on the modeling level (homogeneous model specification for all solution techniques).
Large-scale ecological simulations are natural candidates for distributed discrete event simulation. In optimistic simulation of spatially explicit models, a difficult problem arises when individuals migrate between p...
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ISBN:
(纸本)0818679654
Large-scale ecological simulations are natural candidates for distributed discrete event simulation. In optimistic simulation of spatially explicit models, a difficult problem arises when individuals migrate between physical regions simulated by different logical processes. We present a solution to this problem that uses shared object states. Shared states allow for efficient communication between LPs and for early detection of canceled events. We briefly describe an optimistic simulation environment called EcoKit, which operates on top of the WarpKit implementation of Time Warp. Our experiments with this system on a shared memory multiprocessor show that EcoKit promises to scale well both with the number of processors and the number of individuals simulated.
This paper presents the results of an experimental study to evaluate the effectiveness of multiple synchronization protocols and partitioning algorithms in reducing the execution time of switch-level models of VLSI ci...
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This paper presents the results of an experimental study to evaluate the effectiveness of multiple synchronization protocols and partitioning algorithms in reducing the execution time of switch-level models of VLSI circuits. Specific contributions of this paper include: (i) parallelizing an existing switch-level simulator such that the model can be executed using conservative and optimistic simulation protocols with minor changes, (ii) evaluating effectiveness of several partitioning algorithms for parallelsimulation, and (iii) demonstrating speedups with both consecutive and optimistic simulation protocols for seven circuits, ranging in size from 3 K transistors to about 87 K transistors.
In this paper an approach to provide Web-based framework for distributed execution of collaborative applications is presented. The work is a part of a wider on-going project whose aim is to make environmental simulati...
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ISBN:
(纸本)0818680431
In this paper an approach to provide Web-based framework for distributed execution of collaborative applications is presented. The work is a part of a wider on-going project whose aim is to make environmental simulation models publicly available to the Internet users. The Web computing skeleton has been constructed from prefabricated Web-enabled components with the ability to open and maintain Web connections and provide collaboration over the Internet. The case study illustrates how a single-user simulation system can be embedded in the skeleton, thus becoming widely available distributed application.
distributed computing systems making available large memories and powerful computational resources, allow the analysis of problems of unprecedented complexity. The exploitation of the potential offered by these system...
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ISBN:
(纸本)081867931X
distributed computing systems making available large memories and powerful computational resources, allow the analysis of problems of unprecedented complexity. The exploitation of the potential offered by these systems highly depends upon the availability of efficient tools devoted to the solution of specific problems. The paper describes a distributed approach to the analysis of large GSPN models whose applicability to real systems was often constrained by the explosion in the size of the underlying state space representation. A performing algorithm for distributed construction of large state space graphs generated by GSPN models is described in detail The subsequent distributed numerical solution of the Markov chain is then presented and discussed, along with its current limitations. The implementation of the complete distributed solution tool is integrated with the well known GreatSPN package. The use of the widespread MPI Message Passing library makes the tool portable on a large class of distributed and parallel architectures. Performance results in the case of nets with large state space cardinalities are discussed, considering an experimental low-cost, general purpose PC cluster.
The IDES project at Sandia National Laboratories is developing a large scale portable parallel simulator for use in stockpile stewardship. IDES will use the Breathing-Time-Buckets synchronization protocol;to support I...
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The IDES project at Sandia National Laboratories is developing a large scale portable parallel simulator for use in stockpile stewardship. IDES will use the Breathing-Time-Buckets synchronization protocol;to support IDES development, this paper studies a performance model and describes performance experiments on expected workload and architectural parameters. A new parallel algorithm for terminating the window quickly is also described and analyzed.
The process interaction world view is widely used in the general simulation community for its expressive power and is supported by most modem simulation languages. In parallel discrete event simulation, however its us...
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ISBN:
(纸本)0818679654
The process interaction world view is widely used in the general simulation community for its expressive power and is supported by most modem simulation languages. In parallel discrete event simulation, however its use remains comparatively rare due to the perceived inefficiency (and difficulty) of parallel implementations. We present a new implementation strategy for parallel process-oriented simulation languages. This innovative, semantics-based approach directly addresses two common concerns of such languages. By concentrating on the intrinsic threads of control, we avoid the proliferation of simulation objects (and their associated costs) that might result from a naive translation. More fundamentally, the primary costs associated with process-oriented languages - those of context switching between stacks and, in an optimistic setting, of saving the state of these stacks - are entirely eliminated since our explicit use of continuations avoids the need for stacks in the first place. We similarly obtain cheap and natural thread pre-emption.
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