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4th International Workshop on High Performance Scientific and Engineering Computing with Applications

作者： Chaudhary, V Hase, WL Jiang, H Sun, L Thaker, D Wayne State Univ Inst Comp Sci Detroit MI 48202 USA Texas Tech Univ Dept Chem & Biochem Lubbock TX 79409 USA Northwestern Univ Dept Chem Evanston IL 60208 USA

Different parallelization methods vary in their system requirements, programming styles, efficiency of exploring parallelism, and the application characteristics they can handle. For different situations, they can exhibit totally different performance gains. This paper compares OpenMP, MPI, and Strings for parallelizing a complicated tribology problem. The problem size and computing infrastructure is changed to assess the impact of this on various parallelization methods. All of them exhibit good performance improvements and it exhibits the necessity and importance of applying parallelization in this field.

关键词： molecular dynamics OpenMP MPI distributed shared memory

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A hierarchical computation model for distributed shared-memory machines 9

A hierarchical computation model for distributed shared-memo...

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9th Euromicro Workshop on Parallel and distributed Processing

作者： Rauber, T Rünger, G Univ Halle Wittenberg Inst Informat D-06099 Halle Germany

ISBN: (纸本)0769509886

We present a computation model to describe a clustered memory hierarchy of distributed shared memory machines. The computation model includes the access to shared data stored in different levels of the hierarchy as well as the transfer of entire blocks of data between different levels of the memory. Pure shared memory machines and pure message passing machines can be expressed within the model. As example we use the model to analyze a hierarchical matrix multiplication algorithm.

关键词： shared-memory model distributed shared memory memory hierarchy hierarchical algorithm

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Data-race and concurrent-write freedom are undecidable

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COMPUTER LANGUAGES SYSTEMS & STRUCTURES 2003年第1-2期29卷 1-13页

作者： Campos, AE Suazo, DA Pontificia Univ Catolica Chile Dept Ciencia Computac Santiago 22 Chile

In a distributed shared memory system, sequential consistency is often assumed as the model for the memory, because it is a natural extension from multitasking in uniprocessor systems. Weaker consistency models allow greater concurrency, but programming is harder, because programs may produce unexpected results. Data-race-free (DRF) and concurrent-write-free (CWF) programs have the same set of possible executions both under a sequentially consistent memory and under some other, weaker model, memories. They can be written for a sequential memory and run unchanged under such a weaker-model memory. Since the sets of possible executions are the same, the run will only produce results that are possible under sequential consistency. This article proves the undecidability of both classes of concurrent programs in a language with if statements, loops, barriers, dynamic process creation, dynamic storage, and recursive data structures, under many models weaker than sequential consistency. Moreover, the article also proves that methods that only add synchronization statements to programs written for sequential consistency must produce some conservatively DRF or CWF programs. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： concurrent programming distributed shared memory static analysis data-race-free programs concurrent-write-free programs undecidability

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Performability evaluation of multipurpose multiprocessor systems: The "Separation of concerns" approach

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IEEE TRANSACTIONS ON COMPUTERS 2003年第2期52卷 223-236页

作者： Rabah, M Kanoun, K Univ Rochelle IUT INFO F-17026 La Rochelle France CNRS LAAS F-31077 Toulouse 4 France

The aim of our work is to provide a modeling framework for evaluating performability measures of Multipurpose, Multiprocessor Systems (MMSs). The originality of our approach is in the explicit separation between the architectural and environmental concerns of a system. The overall dependability model, based on Stochastic Reward Nets, is composed of 1) an architectural model describing the behavior of system hardware and software components, 2) a service-level model, and 3) a maintenance policy model. The two latter models are related to the system utilization environment. The results can be used for supporting the manufacturer design choices as well as the potential end-user configuration selection. We illustrate the approach on a particular family of MMSs under investigation by a system manufacturer for Internet and e-commerce applications. As the systems are scalable, we consider two architectures: a reference one composed of 16 processors and an extended one with 20 processors. Then, we use the obtained results to evaluate the performability of a clustered system composed of four reference systems. We evaluate comprehensive measures defined with respect to the end-user service requirements and specific measures in relation to the distributed shared memory paradigm.

关键词： dependability and performability evaluation stochastic reward nets modular modeling multipurpose multiprocessors systems distributed shared memory clustered systems

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Modeling and evaluating the time overhead induced by BER in COMA multiprocessors

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JOURNAL OF SYSTEMS ARCHITECTURE 2003年第13-15期48卷 377-385页

作者： Sharifi, M Zolfaghari, B Iran Univ Sci & Technol Dept Comp Engn Tehran Iran

Designing multiprocessors based on distributed shared memory (DSM) architecture considerably increases their scalability. But as the number of nodes in a multiprocessor increases, the probability of encountering failures in one or more nodes of the system raises as a serious problem. Thus, every large-scale multiprocessor should be equipped. with mechanisms that tolerate node failures. Backward error recovery (BER) is one of the most feasible strategies to build fault tolerant multiprocessors and it can be shown that among various DSM-based architectures, cache only memory architecture (COMA) is the most suitable for implementing BER. The main reason is the existence of built-in mechanisms for data replication in COMA memory system. BER is applicable to COMA multiprocessors with minor hardware redundancy, but it will obviously cause some other kinds of overheads. The most important overhead induced by BER is the time required to produce and store recovery data. This paper introduces an analytical model for predicting the amount of this time overhead and then verifies the correctness of the model through comparing the results predicted from this model with the previously published simulation results. Both the analytical model and simulation results show that the overhead is nearly independent of the number of nodes. The immediate result is that BER is a cost-effective strategy for tolerating node failures in large-scale COMA multiprocessors with large numbers of nodes. (C) 2003 Elsevier Science B.V. All rights reserved.

关键词： BER strategy COMA fault tolerance distributed shared memory

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Message passing and shared address space parallelism on an SMP cluster

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PARALLEL COMPUTING 2003年第2期29卷 167-186页

作者： Shan, HZ Singh, JP Oliker, L Biswas, R NASA Ames Res Ctr Adv Supercomp NAS Div Moffett Field CA 94035 USA Univ Calif Berkeley Lawrence Berkeley Lab NERSC Berkeley CA 94720 USA Princeton Univ Dept Comp Sci Princeton NJ 08544 USA

Currently, message passing (MP) and shared address space (SAS) are the two leading parallel programming paradigms. MP has been standardized with MPI, and is the more common and mature approach;however, code development can be extremely difficult, especially for irregularly structured computations. SAS offers substantial ease of programming, but may suffer from performance limitations due to poor spatial locality and high protocol overhead. In this paper, we compare the performance of and the programming effort required for six applications under both programming models on a 32-processor PC-SMP cluster, a platform that is becoming increasingly attractive for high-end scientific computing. Our application suite consists of codes that typically do not exhibit scalable performance under shared-memory programming due to their high communication-to-computation ratios and/or complex communication patterns. Results indicate that SAS can achieve about half the parallel efficiency of MPI for most of our applications, while being competitive for the others. A hybrid MPI + SAS strategy shows only a small performance advantage over pure MPI in some cases. Finally, improved implementations of two MPI collective operations on PC-SMP clusters are presented. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： PC cluster message passing distributed shared memory benchmark applications parallel performance

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On the design of global object space for efficient multi-threading Java computing on clusters

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PARALLEL COMPUTING 2003年第11-12期29卷 1563-1587页

作者： Fang, WJ Wang, CL Lau, FCM Univ Hong Kong Dept Comp Sci & Informat Syst Syst Res Grp Hong Kong Hong Kong Peoples R China

The popularity of Java and recent advances in compilation and execution technology for Java are making the language one of the preferred ones in the field of high-performance scientific and engineering computing. A distributed Java Virtual Machine supports transparent parallel execution of multi-threaded Java programs on a cluster of computers. It provides an alternative platform for high-performance scientific computations. In this paper, we present the design of a global object space for a distributed JVM. It virtualizes a single Java object heap across machine boundaries to facilitate transparent object accesses. We leverage runtime object connectivity information to detect distributed shared objects (DSOs) that are reachable from threads at different nodes to facilitate efficient memory management in the distributed JVM. Based on the concept of DSO, we propose a framework to characterize object access patterns, along three orthogonal dimensions. With this framework, we are able to effectively calibrate the runtime memory access patterns and dynamically apply optimized cache coherence protocols to minimize consistency maintenance overhead. The optimization devices include an object home migration method that optimizes the single-writer access pattern, synchronized method migration that allows the execution of a synchronized method to take place remotely at the home node of its locked object, and connectivity-based object pushing that uses object connectivity information to optimize the producer-consumer access pattern. Several benchmark applications in scientific computing have been tested on our distributed JVM. We report the performance results and give an in-depth analysis of the effects of the proposed adaptive solutions. (C) 2003 Elsevier B.V. All rights reserved.

关键词： Java cluster computing distributed Java virtual machine distributed shared memory adaptive cache coherence protocol

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An extended coherence protocol for recoverable DSM systems with causal consistency

An extended coherence protocol for recoverable DSM systems w...

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International Conference on Parallel and distributed Processing Techniques and Applications

作者： Brzezinski, J Szychowiak, M Poznan Univ Tech Inst Comp Sci PL-60965 Poznan Poland

ISBN: (纸本)1892512459

This paper presents a coherence protocol for recoverable distributed shared memory, (DSM) systems with causally consistent read-write objects. It uses independent checkpointing tightly integrated with coherence operations. That integration results in high availability of shared objects and ensures fast restoration of the consistent state of DSM in spite of multiple node failures, introducing little overhead. Moreover, in case of network partitioning, the extended protocol ensures that all the processes in a majority partition of the DSM system can continuously access all the objects. The integration can, in some circumstances, also improve the efficiency of the coherence operations.

关键词： fault tolerance distributed shared memory replication recovery check-pointing

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Adding memory resource consideration into workload distribution for software DSM systems

Adding memory resource consideration into workload distribut...

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IEEE International Conference on Cluster Computing

作者： Liang, TY Liu, YT Shieh, CK Natl Kaohsiung Univ Appl Sci Dept Elect Engn Kaohsiung Taiwan

ISBN: (纸本)0769520669

Workload distribution is an important issue for user applications to obtain a good performance on software distributed shared memory (DSM) systems. The workload distribution methods that were previously proposed for DSM systems always considered only CPU power and data sharing but ignored memory availability of processors. However, the cost of memory accesses is also an important factor of determining program performance especially when processors have not sufficient memory space to cache all the data needed by program threads. Therefore, the past methods might make wrong decisions in workload distribution to degrade program performance. To resolve this problem, this paper is dedicated to adding memory resource consideration into workload distribution for software DSM systems. Our experimental result shows that one workload distribution method with memory resource consideration is indeed more effective for minimizing the execution time of DSM applications than another without memory resource consideration.

关键词： workload distribution distributed shared memory memory availability CPU power data sharing

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distributed interactive ray tracing for large volume visualization 03

Distributed interactive ray tracing for large volume visuali...

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IEEE Symposium on Parallel and Large-Data Visualization and Graphics

作者： DeMarle, DE Parker, S Hartner, M Gribble, C Hansen, C Univ Utah Salt Lake City UT 84112 USA

ISBN: (纸本)078038122X

We have constructed a distributed parallel ray tracing system that interactively produces isosurface renderings from large data sets on a cluster of commodity PCs. The program was derived from the SCI Institute's interactive ray tracer (*-Ray), which utilizes small to large shared memory platforms, such as the SGI Origin series, to interact with very large-scale data sets. Making this approach work efficiently on a cluster requires attention to numerous system-level issues, especially when rendering data sets larger than the address space of each cluster node. The rendering engine is an image parallel ray tracer with a supervisor/workers organization. Each node in the cluster runs a multi-threaded application. A minimal abstraction layer on top of TCP links the nodes, and enables asynchronous message handling. For large volumes, render threads obtain data bricks on demand from an object-based software distributed shared memory. Caching improves performance by reducing the amount of data transfers for a reasonable working set size. For large data sets, the cluster-based interactive ray tracer performs comparably with an SGI Origin system. We examine the parameter space of the renderer and provide experimental results for interactive rendering of large (7.5 GB) data sets.

关键词： visualization interactive ray tracing large data cluster computing distributed shared memory

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