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proceedings of the ninth workshop on parallel and distributed simulation

作者： David Bruce Defence Research Agency st. Andrews Road Malvern Worcestershire WR14 3PS United Kingdom

ISBN: (纸本)9780818671203

Optimistic computation methods typically save copies of objects' state information, so that they can recover from erroneous “over-optimistic” computations. Such state saving is generally time and space consuming, and can be rather complicated both to implement and to use.I show how the data structure community's theory of persistence can be used not only to analyse and explain the treatment of state in optimistic systems, but also as a simple yet general mechanism for performing the necessary state saving with minimal impact on application *** results based on a benchmark application and an existing optimistic simulator are presented, showing that providing support for fully general object states is a realistic and practical option. In addition, I show how some existing state saving techniques—including support for shared state—can be derived, and discuss a number of ways in which the model might be extended.

关键词： state saving optimistic methods parallel discrete event simulation persistent data structures

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SGTNE: semi-global time of the next event algorithm 95

SGTNE: semi-global time of the next event algorithm

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proceedings of the ninth workshop on parallel and distributed simulation

作者： Azzedine Boukerche Carl Tropper School of Computer Science McGill University Montreal Canada H3A-2A7

ISBN: (纸本)9780818671203

This paper describes an extension of the TNE algorithm, the objective of which is to increase its parallelism and to break the inter-processor deadlocks inherent with the use of TNE. The algorithm, which we call the SGTNE algorithm (Semi Global TNE), is executed over a cluster of processors as opposed to TNE, which is executed over a cluster of processes assigned to a single processor. SGTNE helps to break the inter-processor deadlocks by executing a shortest path algorithm over a snapshot of the LPs in a cluster of processors. This paper discusses the algorithm and its implementation and reports on the performance results of simulations of a partitioned FCFS queueing network model executed on the Intel Paragon A4 multiprocessor machine. We also examine the impact of partitioning on the efficient implementation of the SGTNE algorithm. The results obtained indicate that SGTNE yields good speedups and that a partitioning which makes use of a strongly connected component algorithm results in a reduction of 30% in the running time of a simulation when compared to simple partitioning strategies. The results also indicate that SGTNE outperforms TNE.

关键词： discrete event simulation SGTNE partitioning parallel algorithms FCFS queueing network model inter-processor deadlock parallelism shortest path algorithm performance results

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Buffer management in shared-memory Time Warp systems 95

Buffer management in shared-memory Time Warp systems

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proceedings of the ninth workshop on parallel and distributed simulation

作者： Richard M. Fujimoto Kiran S. Panesar College of Computing Georgia Institute of Technology Atlanta GA

ISBN: (纸本)9780818671203

Mechanisms for managing message buffers in Time Warp parallel simulations executing on cache-coherent shared-memory multiprocessors are studied. Two simple buffer management strategies called the sender pool and receiver pool mechanisms are examined with respect to their efficiency, and in particular, their interaction with multiprocessor cache-coherence protocols. Measurements of implementations on a Kendall Square Research KSR-2 machine using both synthetic workloads and benchmark applications demonstrate that sender pools offer significant performance advantages over receiver pools. However, it is also observed that both schemes, especially the sender pool mechanism, are prone to severe performance degradations due to poor locality of reference in large simulations using substantial amounts of message buffer memory. A third strategy called the partitioned buffer pool approach is proposed that exploits the advantages of sender pools, but exhibits much better locality. Measurements of this approach indicate that the partitioned pool mechanism yields substantially better performance than both the sender and receiver pool schemes for large-scale, small-granularity parallel simulation *** central conclusions from this study are: (1) buffer management strategies play an important role in determining the overall efficiency of multiprocessor-based parallel simulators, and (2) the partitioned buffer pool organization offers significantly better performance than the sender and receiver pool schemes. These studies demonstrate that poor performance may result if proper attention is not paid to realizing an efficient buffer management mechanism.

关键词： message buffers multiprocessor-based parallel simulators buffer management message buffer memory multiprocessor cache-coherence protocols Kendall Square Research KSR-2 machine mall-granularity parallel simulation applications discrete event simulation cache-coherent shared-memory multiprocessors multiprocessing programs shared memory systems buffer storage message passing severe performance degradations sender pool time warp simulation receiver pool storage management partitioned pool mechanism shared-memory time warp systems partitioned buffer pool approach

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Comparative analysis of periodic state saving techniques in time warp simulators 95

Comparative analysis of periodic state saving techniques in ...

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proceedings of the ninth workshop on parallel and distributed simulation

作者： Josef Fleischmann Philip A. Wilsey Institute of Electronic Design Automation Technical University of Munich D-80290 Munich Germany Center for Digital Systems Engineering Dept of ECECS PO Box 210030 Cincinnati Ohio

ISBN: (纸本)9780818671203

Checkpointing in a time warp synchronized parallel simulator is a necessary and potentially expensive operation. In the simple case, a time warp simulator checkpoints every χ events, for some fixed value χ. For larger values of χ, the simulator requires less overhead for saving the state, but incurs an increased latency during rollback. Thus, the problem is to balance the time to save states against the time to coast forward upon rollback. Unfortunately, a static determination of a optimal value for χ is very difficult and can vary widely, even between closely related instances of a time warp simulator. Furthermore, the optimal checkpoint interval may actually vary over the lifetime of the *** address these problems, several investigators have proposed dynamically adjusting the checkpoint interval χ as the simulation progresses. 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 (digital system simulation from VHDL descriptions) 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 than the best static value. Furthermore, the best algorithms performed as much as 12% better than the best static value.

关键词： latency discrete event simulation time warp simulation periodic state saving techniques hardware description languages heuristic algorithm VHDL descriptions checkpointing rollback time warp simulators

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Clustered time warp and logic simulation 95

Clustered time warp and logic simulation

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proceedings of the ninth workshop on parallel and distributed simulation

作者： Hervé Avril Carl Tropper School of Computer Science McGill University Montréal Canada H3A 2A7 and Hutchison Avenue Software Corporation Montréal Canada School of Computer Science McGill University Montréal Canada H3A 2A7

ISBN: (纸本)9780818671203

We present, in this paper, a hybrid algorithm which makes use of Time Warp between clusters of LPs and a sequential algorithm within the cluster. Time Warp is, of course, traditionally implemented between individual LPs. The algorithm was implemented in a digital logic simulator, and its performance compared to that of Time *** upon this platform we develop a family of three checkpointing algorithms, each of which occupies a different point in the spectrum of possible trade-offs between memory usage and execution time. The algorithms were implemented on several digital logic circuits and their speed, number of states saved and maximal memory consumption were compared to those of Time Warp. One of the algorithms saved between 35 and 50% of the maximal memory consumed by Time Warp (depending upon the number of processors used), while the other two decreased the maximal usage up to 30%. The latter two algorithms exhibited a speed comparable to Time Warp, while the first algorithm was 30-60% *** algorithms are also simpler to implement than optimal checkpointing algorithms.

关键词： circuit analysis computing digital logic circuits hybrid algorithm sequential algorithm clustered time warp logic CAD time warp simulation checkpointing algorithms digital logic simulator logic simulation maximal memory consumption

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proceedings of the 8th workshop on parallel and distributed simulation, PADS 1994

Proceedings of the 8th Workshop on Parallel and Distributed ...

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8th workshop on parallel and distributed simulation, PADS 1994

ISBN: (纸本)1565550277

The proceedings contain 25 papers. The topics discussed include: paralilel proximity detection and the distribution list algorithm;a unified framework for conservative and optimistic distributed simulation;investigations in adaptive distributed simulation;ports: a parallel, optimistic, real-time simulator;a distributed memory lapse: parallel simulation of message-passing programs;discrete-event simulation and the event horizon;a generalized carrier-null method for conservative parallel simulation;cooperative acceleration: robust conservative distributed discrete event simulation;and stability of event synchronization in distributed discrete event simulation.

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MEMORY MANAGEMENT ALGORITHMS FOR OPTIMISTIC parallel simulation (REPRINTED FROM proceedings OF 1992 workshop ON parallel AND distributed simulation)

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INFORMATION SCIENCES 1994年第1-2期77卷 119-140页

作者： LIN, YB Bell Communications Research Rm. 2D297 445 South St. Morristown New Jersey 07962-1910 USA

This paper studies the space complexity of an optimistic parallel simulation protocol called Time Warp. We evaluate four Time Warp memory management algorithms: fossil collection, message sendback. cancelback, and artificial rollback. We identify two criteria in designing Time Warp memory management algorithms. Criterion 1 tests if a memory management algorithm ensures that Time Warp simulation always stops (either completes or terminates when memory is exhausted). If an algorithm does not satisfy this criterion, then the simulation may be trapped in an infinite loop. Criterion 2 tests if a memory management algorithm is independent of processor parameters (e.g., number of processors available for the parallel simulation, processor speed, and interprocessor communication costs). We show that if an algorithm satisfies this second criterion, then the amount of memory consumed by Time Warp simulation is bounded by the amount consumed by sequential simulation. For algorithms that do not have full control of uncommitted objects (e.g., fossil collection and message sendback), Criterion 2 is not satisfied in general. For algorithms that have full control of uncommitted objects (e.g., cancelback and artificial rollback), special treatments are necessary to satisfy Criterion 1 (i.e., to ensure that the algorithms do not cancel future objects such that global virtual time never advances).

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parallel independent replicated simulation on a network of workstations 94

Parallel independent replicated simulation on a network of w...

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8th workshop on parallel and distributed simulation, PADS 1994

作者： Lin, Yi-Bing Bellcore MorristownNJ United States

ISBN: (纸本)1565550277

parallel independent replicated simulation (PIRS) is an effective approach to speed up the simulation processes. In a PIRS, a single simulation run is executed by multiple computers in parallel. The statistical properties for a PIRS may be affected by the scheduling policies. For an unbiased PIRS scheduling policy, a reliable distributed computing environment is required. We consider an unbiased PIRS scheduling policy on a distributed platform such as a network of workstations. We observe that including more computing resources may degrade the performance of PIRS. Simple rules are proposed to select processors for PIRS.

关键词： Scheduling

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Maya: A simulation platform for distributed shared memories 94

Maya: A simulation platform for distributed shared memories

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8th workshop on parallel and distributed simulation, PADS 1994

作者： Agrawal, Divyakant Choy, Manhoi Leong, Hong Va Singh, Ambuj K. Department of Computer Science University of California at Santa Barbara Santa BarbaraCA93106 United States

ISBN: (纸本)1565550277

Maya is a simulation platform for evaluating the performance of parallel programs on parallel architectures. It allows the rapid prototyping of memory protocols with varying degrees of coherence and facilitates the study of the impact of these protocols on application programs. The design of Maya and its simulation mechanism are discussed. Performance results on architectural simulation with different memory coherence protocols are presented. parallel discrete event simulation techniques are adopted for the executiondriven simulation of parallel architectures.

关键词： parallel architectures

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Investigations in adaptive distributed simulation 94

Investigations in adaptive distributed simulation

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8th workshop on parallel and distributed simulation, PADS 1994

作者： Hamnes, Donald O. Tripathi, Anand Department of Computer Science University of Minnesota MinneapolisMN55455 United States

ISBN: (纸本)1565550277

A new adaptive protocol for distributed discrete event simulation is proposed. This protocol spans the continuum of protocols from conservative to optimistic allowing each process in a distributed simulation to adapt to the specific simulation problem at runtime. An actual implementation of the protocol has been tested on a network of workstations for a closed queueing system. The results are very favorable and the algorithm has outperformed a conservative and an optimistic protocol in some cases.

关键词： Discrete event simulation

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