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5th International Conference on Parallel Processing, Euro-Par 1999

作者： Sharma, Girindra D. Abu-Ghazaleh, Nael B. Rajasekaran, Umesh Kumar V. Wilsey, Philip A. Computer Architecture Design Laboratory Dept. of ECECS PO Box 210030 Cincinnati OH 45221-0030 United States

ISBN: (纸本)3540664432

Since the message delivery time of asynchronous applications is unpredictable, each asynchronous process must probe (or poll) the network for new messages regularly. If polling is carried out too aggressively, a majority of the probes will be unsuccessful. However, the cost for probing the network is similar to the cost of communication operations. Thus, optimizing the message reception behavior has a significant impact on the performance of the application. This paper studies this problem, and develops a cost model to optimize the polling frequency. We also develop strategies to optimize the message delivery behavior, and study their impact on the performance of a parallel discrete event simulator. © Springer-Verlag Berlin Heidelberg 1999.

关键词： Costs

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An object-oriented framework for parallel simulation of ultra-large communication networks 1

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3rd International Symposium on Computing in Object-Oriented Parallel Environments, ISCOPE 1999

作者： Rao, Dhananjai Madhava Wilsey, Philip A. Computer Architecture Design Laboratory Dept. Of ECECS University of Cincinnati P.O. Box 210030 CincinnatiOH45221-0030 United States

ISBN: (数字)9783540466970

ISBN: (纸本)3540668187

Communication networks have steadily increased in size and complexity to meet the growing demands of applications. Simulations have been used to model and analyze modern communication networks. Modeling and simulation of networks involving thousands of nodes is hard due to their sheer size and complexity. Complete models of the ultra- large networks need to be simulated in order to conduct in-depth studies of scalability and performance. Parallel simulation techniques need to be efficiently utilized to obtain optimal time versus resource tradeoffs. Due to the complexity of the system, it becomes critical that the design of such frameworks follow well established design principles such as object oriented (OO) design, so as to meet the diverse requirements of portability, maintainability, extensibility, and ease of use. This paper presents the issues involved in the design and implementation of an OO framework to enable parallel simulation of ultra-large communication networks. The OO techniques utilized in the design of the framework and the application program interfaces needed for model development are presented along with some experimental results. © Springer-Verlag Berlin Heidelberg 1999.

关键词： Complex networks

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OFC: A distributed fossil-collection algorithm for time-warp 12th

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12th International Symposium on Distributed Computing, DISC 1998

作者： Young, Christopher H. Abu-Ghazaleh, Nael B. Wilsey, Philip A. Computer Architecture Design Laboratory Dept. Of ECECS PO Box 210030 CincinnatiOH45221-0030 United States

ISBN: (纸本)3540650660

In the Time-Warp synchronization model, the processes must occasionally interrupt execution in order to reclaim memory space used by state and event histories that are no longer needed (fossil-collection). Traditionally, fossil-collection techniques have required the processes to reach a consensus on the Global Virtual-Time (GVT) — the global progress time. Events with time-stamps less than GVT are guaranteed to have been processed correctly;their histories can be safely collected. This paper presents Optimistic Fossil-Collection (OFC), a new fossil-collection algorithm that is fully distributed. OFC uses a local decision function to estimate the fossilized portion of the histories (and optimistically collects them). Because a global property is estimated using local information only, an erroneous estimate is possible. Accordingly, OFC must also include a recovery mechanism to be feasible. An uncoordinated distributed checkpointing algorithm for Time-Warp that is domino-effect free and lightweight is used. We show that, in addition to eliminating the overhead for GVT estimation, OFC has several desireable memory-management properties. © Springer-Verlag Berlin Heidelberg 1998.

关键词： Artificial intelligence

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An active layer extension to MPI 5th

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5th European Meeting of the Parallel Virtual Machine and Message Passing Interface, EuroPVM/MPI 1998

作者： Chetlur, Malolan Sharma, Girindra D. Abu-Ghazaleh, Nael Rajasekaran, Umesh Kumar V. Wilsey, Philip A. Computer Architecture Design Laboratory Dept. of ECECS University of Cincinnati PO Box 210030 CincinnatiOH45221-0030 United States

ISBN: (纸本)3540650415

Communication costs represent a significant portion of the execution time of most distributed applications. Thus, it is important to optimize the communication behavior of the algorithm to match the capabilities of the underlying communication fabric. Traditionally, optimizations to the communication behavior have been carried out statically and at the application level (optimizing partitioning, using the most appropriate communication protocols, etc). This paper introduces a new class of optimizations to communication: active run-time matching between the application communication behavior and the communication layer. We propose an active layer extension to the Message Passing Interface (MPI) that dynamically reduces the average communication overhead associated with message sends and receives. The active layer uses dynamic message aggregation to reduce the send overheads and infrequent polling to reduce the receive overhead of messages. The performance of the active layer is evaluated using a number of applications. © Springer-Verlag Berlin Heidelberg 1998.

关键词： Message passing

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Unsynchronized parallel discrete event simulation

Unsynchronized parallel discrete event simulation

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Simulation Winter Conference

作者： D.M. Rao N.V. Thondugulam R. Radhakrishnan P.A. Wilsey Computer Architecture Design Laboratory Cincinnati OH USA

Distributed synchronization for parallel simulation is generally classified as being either optimistic or conservative. While considerable investigations have been conducted to analyze and optimize each of these synchronization strategies, very little study on the definition and strictness of causality have been conducted. Do we really need to preserve causality in all types of simulations? The paper attempts to answer this question. We argue that significant performance gains can be made by reconsidering this definition to decide if the parallel simulation needs to preserve causality. We investigate the feasibility of unsynchronized parallel simulation through the use of several queuing model simulations and present a comparative analysis between unsynchronized and Time Warp simulation.

关键词： Discrete event simulation Computational modeling Analytical models Time warp simulation computer architecture Queueing analysis Parallel processing Laboratories Performance gain Performance analysis

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On-line configuration of a time warp parallel discrete event simulator

On-line configuration of a time warp parallel discrete event...

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International Conference on Parallel Processing (ICPP)

作者： R. Radhakrishnan N. Abu-Ghazaleh M. Chetlur P.A. Wilsey Department of ECECS Computer Architecture Design Laboratory Cincinnati OH USA

In time warp simulations, the overheads associated with rollbacks, state-saving and the communication induced by rollbacks are the chief contributors to the cost of the simulation; thus, these aspects of the simulation have been primary targets for optimizations. Unfortunately, the behavior of the time warp simulation is highly dynamic and greatly influenced by the application being simulated. Thus, the suggested optimizations are only effective for certain intervals of the simulation. This paper argues that the performance of time warp simulators benefits from a dynamic on-line decision process that selects and configures the sub-algorithms implementing the different aspects of the simulator to best match the current behavior of the simulation. In particular we study control strategies to dynamically: (i) adjust the checkpointing (or state-saving) interval (ii) select the cancellation strategy (lazy or aggressive), and (iii) determine the policy for aggregating the application messages (an optimization that significantly improves the performance in message passing environments). The strategies have been implemented in the WARPED time warp simulation kernel and the performance obtained via the dynamically controlled optimizations is shown to surpass that of their best performing static counterparts.

关键词： Discrete event simulation Time warp simulation Computational modeling Kernel computer architecture Laboratories Cost function design optimization Read only memory Message passing

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SAVANT/TyVIS/WARPED: components for the analysis and simulation of VHDL

SAVANT/TyVIS/WARPED: components for the analysis and simulat...

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IEEE International Conference on Verilog HDL

作者： P.A. Wilsey D.E. Martin K. Subramani Department of ECECS Computer Architecture Design Laboratory Cincinnati OH USA

The SAVANT, QUEST II, and HEPE research programs at the University of Cincinnati include the development and distribution of VHDL analysis and simulation capabilities. These capabilities are being freely distributed for non-commercial use. The SAVANT project is underway specifically to develop a VHDL analyzer with a well-documented, extensible intermediate form; the main objective is to smooth the integration of VHDL technology into university and industrial research programs. The SAVANT project is funded through the Air Force SBIR program and is a joint activity between the University of Cincinnati and MTL Systems, Inc. The QUEST II program is investigating parallel algorithms and architectures for simulation, behavioral synthesis, and ATPG. The HEPE program is investigating (in part) novel strategies for relaxing causal orders in the parallel simulation of active networks. As part of the QUEST II/HEPE simulation activities, a VHDL simulation kernel is being developed that will operate with the SAVANT intermediate form for sequential or parallel execution of VHDL models (a C++ code generator from the SAVANT intermediate is being jointly developed by the SAVANT and QUEST II programs). All of the software from the QUEST and HEPE simulation programs is freely available for use (commercial or otherwise).

关键词： Analytical models Computational modeling Electrical capacitance tomography Read only memory Contracts Discrete event simulation Kernel computer architecture Laboratories Automatic test pattern generation

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Unsynchronized parallel discrete event simulation 98

Unsynchronized parallel discrete event simulation

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Proceedings of the 30th conference on Winter simulation

作者： Dhananjai Madhava Rao Narayanan V. Thondugulam Radharamanan Radhakrishnan Philip A. Wilsey Computer Architecture Design Laboratory P.O. Box 210030 Cincinnati Ohio

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The SAVANT project

The SAVANT project

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IEEE National Conference on Aerospace and Electronics (NAECON)

作者： P.A. Wilsey D.E. Martin H. Hirsch Computer Architecture Design Laboratory Department of ECECS University of Cincinnati Cincinnati OH USA MTL Systems Inc. Dayton OH USA

The SAVANT project is a joint program between the Air Force, MTL Systems, Inc. and the University of Cincinnati to develop a VHDL analyzer that is freely redistributable for noncommercial use. The goal is to facilitate the insertion of VHDL technology into the government, industrial, and university research and development programs. The analyzer validates the correctness of the input VHDL and builds an intermediate representation in memory for manipulation by backend analysis tools (e.g., behavioral synthesis, fault modeling, and simulation code generators). The intermediate (called AIRE/CE) is well-documented, in review for standardization, and in use by other commercial vendors. The SAVANT technology is freely available in source code form and, under separate programs, the University of Cincinnati is also developing a backend code generator and simulation kernel so that complete front-to-back analysis and simulation activities can be performed with nearly free software.

关键词： Analytical models Object oriented modeling Performance analysis Contracts computer architecture Laboratories Plasma welding Research and development Standardization Kernel

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Variable instruction scheduling for MIMD interpretation on pipelined SIMD machines and for compositional instruction sets

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Concurrency and Computation: Practice and Experience 1998年第1期9卷

作者： NAEL B. ABU-GHAZALEH PHILIP A. WILSEY Computer Architecture Design Laboratory Department of ECECS PO Box 210030 University of Cincinnati Cincinnati OH 45221–0030 USA

Functional parallelism may be supported on SIMD machines by interpretation. The programs and data of each function are loaded on the processing elements (PEs), and the control unit of the machine executes a central control algorithm that causes the concurrent interpretation of these functions. The performance of this paradigm has been shown to benefit considerably from a variable instruction issue schedule that delays execution of expensive and rarely occurring operations. Two new features of the interpretation paradigm, namely pipelined SIMD machines and compositional instruction sets, change the nature of the mathematical model used for variable instruction scheduling significantly. In the paper, a previously developed mathematical model of the interpretation process is extended to allow for compositional instructions and pipelining. We develop and present algorithms that produce variable instruction schedules for the extended model and investigate whether the variable instruction issue is useful for these cases. We show that the variable instruction issue improves the performance of pipelined machines but is not very effective for compositional instruction sets, especially when the composition matrix is not sparse. © 1997 by John Wiley & Sons, Ltd.

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