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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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.
This paper describes an approach to discrete event simulation modeling that appears to be effective for developing portable and efficient parallel execution of models of large distributed systems and communication net...
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This paper describes an approach to discrete event simulation modeling that appears to be effective for developing portable and efficient parallel execution of models of large distributed systems and communication networks. In this approach, the modeler develops sub-models using an existing sequential simulation modeling tool, using the full expressive power of the tool. A set of modeling language extensions permit automatically synchronized communication between sub-models;however, the automation requires that any such communication must take a non-zero amount of simulation time. Within this modeling paradigm, a variety of conservative synchronization protocols can transparently support conservative execution of sub-models on potentially different processors. A specific implementation of this approach, U.P.S. (Utilitarian parallel Simulator), is described, along with performance results on the Intel Paragon.
This paper reports on the performance of four parallel algorithms for simulating an associative cache operating under the LRU (Least-Recently-Used) replacement policy. Three of the algorithms are implemented on the Ma...
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This paper reports on the performance of four parallel algorithms for simulating an associative cache operating under the LRU (Least-Recently-Used) replacement policy. Three of the algorithms are implemented on the MasPar MP-2. Another algorithm is a parallelization of an efficient serial algorithm on the Intel Paragon. We assess the strengths and weaknesses of these algorithms as a function of problem size and characteristics, and compare their performance on traces derived from execution of three SPEC92 benchmark programs.
This paper presents an approach for speculative parallel execution of rendezvous-synchronized simulations. Rendezvous-synchronized simulation is based on the notions of processes and gates and on the rendezvous mechan...
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This paper presents an approach for speculative parallel execution of rendezvous-synchronized simulations. Rendezvous-synchronized simulation is based on the notions of processes and gates and on the rendezvous mechanism defined in the basic process algebra of Lotos - a standard formal specification language for temporal ordering[2]. Time is introduced via a mechanism similar to the delay behaviour annotation provided by the Topo toolset[4-6]. The algorithm allows speculative gate activations. This increases the available parallelism while ensuring correct execution of the computation. The model is used to describe closed stochastic queueing network simulations. Analysis of their execution results suggests that the model makes available a promising degree of parallelism.
Distributing computation among multiple processors is one approach to reducing simulation time for large VLSI circuit designs. However, parallelsimulation introduces the problem of how to partition the logic gates an...
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Distributing computation among multiple processors is one approach to reducing simulation time for large VLSI circuit designs. However, parallelsimulation introduces the problem of how to partition the logic gates and system behaviors of the circuit among the available processors in order to obtain maximum speedup. A complicating factor that is often ignored is the effect of the time-synchronization protocol (conservative [1] or optimistic [2]). Inherent in the partitioning problem is the question of how to effectively measure the relative quality of a partition. This paper describes an objective cost function for measuring the relative quality of a task partition that includes a synchronization factor for a conservative NULL-message protocol. A graph-based partitioning tool based on this cost function is used to perform the static task allocation for parallelsimulation of a structural VHDL circuit. Results for two 1000 - 4000 gate circuits demonstrate that the additional consideration of the synchronization protocol in the cost function generates partitions that exhibit improved speedup.
This paper analyzes three previous techniques for dynamically sizing checkpoint intervals and presents a new, heuristic algorithm for this purpose. All four techniques are implemented in a common application domain an...
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This paper analyzes three previous techniques for dynamically sizing checkpoint intervals and presents a new, heuristic algorithm for this purpose. All four techniques are implemented in a common application domain and a direct comparison between the algorithms is performed. The results show a significant difference in the performance of the implemented algorithms. However, in virtually all cases, the dynamic algorithms performed near or better that the best static value. Moreover, the best algorithms performed as much as 12% better the best static value.
In optimistic simulations, Global Virtual Time (GVT) is considered to be the fundamental synchronization concept. During the recent years, a number of methods have been proposed for determining GVT, however most of th...
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In optimistic simulations, Global Virtual Time (GVT) is considered to be the fundamental synchronization concept. During the recent years, a number of methods have been proposed for determining GVT, however most of these methods have been found to either focus on specific types of simulation problems or assume specific hardware support. In this study, the GVT problem is addressed in the context of scalability, efficiency, portability, flow control, interactive support and real time use. Additionally, a new GVT algorithm called SPEEDES GVT that provides flow control by processing events risk-free while flushing out messages during the GVT computation is proposed.
In the present paper, we present some experimental results about the parallel numerical simulation of a time dependent partial differential equation, the two dimensional nonlinear Schrödinger equation, on a messa...
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