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IEEE workshop on Computers in Power Electronics

作者： V.P. Guzik V.E. Zolotovsky Yu.V. Chemukhin S.V. Tretyakov O.A. Muntyan R.A. Dougal Taganrog State Univ. of Radio-Eng. Russia Taganrog State University of Radio Engineering Taganrog Russia University of South Carolina Columbia SC USA

ISBN: (纸本)0780365615

Power electronic systems are described by nonlinear differential equations, typically of high order. simulation of such systems increasingly requires the high speeds available only on multiprocessor computing systems. However, the traditional methods for partitioning the system are rather inconvenient, primarily because of the additional burden created by the current operation associated with distributed systems. The concepts and methods of structural modeling provide a way to overcome this difficulty. The essence of structural modeling is the assignment of some specific computing resource to each object of the simulated physical system. The simulation of each object then operates as a formal independent procedure, and interactions between objects are implemented on a data link level. This allows parallel execution of the separate procedures on the allocated multiprocessor computing hardware. This provides two advantages: (1) a decrease in simulation time, and (2) simplification of the programming process.

关键词： Power system modeling Computational modeling Circuit simulation Power electronics Differential equations Multiprocessing systems Power system interconnection Power system simulation Libraries Physics computing

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Removing the latency overhead of the ITB mechanism in COWs with source routing

Removing the latency overhead of the ITB mechanism in COWs w...

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Euromicro Conference on parallel, distributed and Network-Based Processing

作者： J. Flich M.P. Malumbres P. Lopez J. Duato Dpto. of Computer Engineering (DISCA) Universidad Politécnica de Valencia Valencia Spain

ISBN: (纸本)0769514448

Clusters of workstations (COWs) are becoming increasingly popular as a cost-effective alternative to parallel computers. The in-transit buffer (ITB) mechanism can improve network performance when applied to COWs with irregular topology and source routing. This mechanism considerably improves the performance of this kind of network when compared to current source routing algorithms; however, it introduces a latency penalty. An implementation of this mechanism was performed, showing that the latency overhead of the mechanism may be noticeable, especially for short messages and at low network loads. In this paper, we analyze in detail the latency overhead of ITBs, proposing several mechanisms to reduce, hide and remove it. Firstly, we show, by simulation, the effect of an ITB implementation that is much slower than the one implemented. Then we propose three mechanisms that try to overcome the latency penalty. All the mechanisms are simple and can be easily implemented; also, they are out of the critical path of the ITB packet-processing procedure. The results show very good behaviour of the proposed mechanisms, considerably reducing or even completely removing the latency overhead.

关键词： Delay Cows Routing Network topology Concurrent computing Workstations Local area networks Telecommunication traffic Large-scale systems parallel processing

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Fast-software-checkpointing in optimistic simulation: embedding state saving into the event routine instructions 99

Fast-software-checkpointing in optimistic simulation: embedd...

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proceedings of the thirteenth workshop on parallel and distributed simulation

作者： Francesco Quaglia Dipartimento di Informatica e Sistemistica Università di Roma "La Sapienza" Via Salaria 113 00198 Roma Italy

ISBN: (纸本)9780769501550

In this paper we present a software approach, namely Fast-Software-Checkpointing (FSC), to reduce the running time of the state saving protocol in optimistic parallel discrete event simulation. The idea behind FSC is to use the instructions performed during the execution of an event as part of the state saving protocol, hence the total number of instructions due to state saving is reduced. Under FSC the time for saving the state of a logical process prior to the execution of an event e requires an amount of time proportional to the amount of state variables not updated by e's execution, as only these variables must be copied. This outlines that FSC shows some dualism with respect to incremental state saving. We show, however, that there exists a basic difference between the two solutions as in FSC some of the state saving instructions are actually event routine instructions, while in incremental state saving they are only added and mixed to the latter ones. We also present a simple software architecture to support FSC and simulation results to demonstrate the effectiveness of such solution. The obtained data show that FSC, combined with a sparse state saving strategy, may represent the best checkpointing solution in case of both medium/small state granularity simulations and large state granularity simulations even with small (but non-minimal) portions of the state updated by event execution. FSC may result therefore suited for a wide class of simulation problems.

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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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Semi-asynchronous checkpointing for optimistic simulation on a Myrinet based NOW 01

Semi-asynchronous checkpointing for optimistic simulation on...

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proceedings of the fifteenth workshop on parallel and distributed simulation

作者： Francesco Quaglia Andrea Santoro Dipartimento di Informatica e Sistemistica Università di Roma "La Sapienza" Via Salaria 113 00198 Roma Italy

ISBN: (纸本)9780769511047

Great effort has been devoted to the design of optimized checkpointing strategies for optimistic parallel discrete event simulators. On the other hand there is less work in the direction to improve the execution mode of any single checkpoint operation. Specifically, checkpoint operations are typically charged to the CPU, thus leading to freezing of the simulation application while checkpointing is in progress, i.e. the execution mode of the checkpointing protocol is typically synchronous. In this paper we focus on improvements of the execution mode and present a software architecture, designed for myrinet based Network of Workstations (NOWs), to avoid application freezing during any checkpoint operation, thus moving the execution itself towards an asynchronous mode. This is done by charging checkpoint operations to a hardware component distinct from the CPU, namely a DMA engine. On the other hand, totally asynchronous checkpointing could suffer from data inconsistency whenever the content of a state buffer is accessed for further modifications while a checkpoint operation involving it is not yet completed. To avoid this, the architecture includes functionalities for resynchronization on demand. We have used these functionalities to implement an execution mode of the checkpointing protocol we refer to as semi-asynchronous. By the results of an experimental study we argue that the semi-asynchronous mode can be an effective solution to almost completely remove the delay associated with any checkpoint operation from the completion time of the simulation.

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Quantum neurocomputation and signal processing

Quantum neurocomputation and signal processing

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IEEE workshop on Neural Networks for Signal Processing

作者： H. Eghbalnia A. Assadi University of Wisconsin Madison USA

We consider a quantum computational algorithm that can be used to determine (probabilistically) how close a given signal is to one of a set of previously observed signals stored in the state of a quantum neurocomputional machine. The realization of a new quantum algorithm for factorization of integers by Shor and its implication to cryptography has created a rapidly growing field of investigation. Although no physical realization of a quantum computer is available, a number of software systems simulating a quantum computation process exist. In light of the rapidly increasing power of desktop computers and their ability to carry out these simulations, it is worthwhile to investigate possible advantages as well as realizations of quantum algorithms in signal processing applications. The algorithm presented offers a glimpse of the potential of this approach. Neural networks (NN) provide a natural paradigm for parallel and distributed processing of a wide class of signals. Neural networks within the context of classical computation have been used for approximation and classification tasks with some success. We propose a model for quantum neurocomputation (QN) and explore some of its properties and potential applications to signal processing in an information theoretic context.

关键词： Signal processing Quantum computing Signal processing algorithms Neural networks Physics computing Computational modeling Computer simulation Cryptography Software systems Application software

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proceedings of the 16th international workshop on high-level parallel programming models and supportive environments

IEEE International Symposium on Parallel and Distributed Pro...

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IEEE International Symposium on parallel and distributed Processing workshops and Phd Forum 2011年 1139-1140页

作者： Hoefler, Torsten Eigenmann, Rudolf Gerndt, Michael Müller, Frank Rasmussen, Craig Schulz, Martin Alam, Sadaf Balaji, Pavan Barrett, Richard Bode, Brett Bosilca, George Bronevetsky, Greg Danalis, Anthony De Supinski, Bronis Ding, Chen Fahringer, Thomas Ishikawa, Yutaka Knüpfer, Andreas Mohr, Bernd Scholz, Sven-Bodo Skjellum, Tony Snir, Marc Tillier, Fabian Larsson, Jesper Willcock, Jeremiah Wolf, Felix Blue Waters Directorate NCSA University of Illinois Urbana-Champaign United States Purdue University United States Technische Universität München Germany North Carolina State University United States Los Alamos National Laboratory United States Lawrence Livermore National Laboratory United States Swiss National Supercomputing Centre Switzerland Argonne National Laboratory United States Sandia National Laboratories United States National Center for Supercomputing Applications United States University of Tennessee Knoxville United States University of Rochester United States University of Innsbruck Austria University of Tokyo Japan Technische Universität Dresden Germany Forschungszentrum Jülich Germany University of Herfordshire United Kingdom University of Alabama Birmingham United States University of Illinois Urbana-Champaign United States Microsoft United States Träff University of Vienna Austria Indiana University United States German Research School for Simulation Sciences Germany

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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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State saving for interactive optimistic simulation 97

State saving for interactive optimistic simulation

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proceedings of the eleventh workshop on parallel and distributed simulation

作者： Steve Franks Fabian Gomes Brian Unger John Cleary Department of Computer Science University of Waikato Te Whare Wananga o Waikato Hamilton New Zealand and Department of Computer Science The University of Calgary 2500 University Drive N.W. Calgary Alberta T2N 1N4 Canada Department of Computer Science The University of Calgary 2500 University Drive N.W. Calgary Alberta T2N 1N4 Canada Department of Computer Science University of Waikato Te Whare Wananga o Waikato Hamilton New Zealand

ISBN: (纸本)9780818679650

Time Warp's optimistic scheduling requires the maintenance of simulation state history to support rollback in the event of causality violations. State history, and the ability to rollback the simulation, can provide unique functionality for human-in-the-loop simulation environments. This paper investigates the use of Time Warp to output valid simulation state in a near real-time manner, re-execute portions of the simulation, and interactively probe simulation values to ascertain underlying causes of transient behavior.A shared-memory, multi-threaded interactive simulation architecture is presented and the additional state saving requirements imposed by interactivity are examined. The shortcomings of existing state saving schemes lead us to propose Multiplexed State Saving (MSS). By interleaving checkpointing and incremental state logs MSS provides bounded rollback costs and asynchronous access to prior simulation state. The interaction algorithms and MSS form a scalable, bounded cost component suitable for use in a real-time interactive Time Warp system.

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Identifying and localizing robots in a multi-robot system environment

Identifying and localizing robots in a multi-robot system en...

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IEEE International workshop on Intelligent Robots and Systems (IROS)

作者： K. Kato H. Ishiguro M. Barth Department of Computer and Communication Sciences Wakayama University Wakayama Japan Department of Social Informatics Kyoto University Sakyo Kyoto Japan Department of Electrical Engineering University of California Riverside CA USA

Development of multiple robot systems which solve complex and dynamic problems in parallel and distributed manners is one of the key issues in robotics research. The multiple robot systems require robust methods to identify robots for collaborative behaviors. This paper proposes a method using omnidirectional vision sensors for the identification between the robots. In addition to the several advantages of the omnidirectional vision sensor as a vision of a mobile robot, the omnidirectional vision sensor brings a significant benefit for realizing collaborative behaviors in multiple robot systems. After discussing on the algorithm, this paper shows several simulation results and real experimental results in a real environment.

关键词： Multirobot systems Robot sensing systems Robot vision systems Mobile robots parallel robots Sensor systems Cameras Mirrors Concurrent computing Informatics

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