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Highly parallel structured adaptive mesh refinement using parallel language-based approaches

PARALLEL COMPUTING 2001年第1-2期27卷 37-70页

作者： Balsara, DS Norton, CD NASA Jet Prop Lab CALTECH MS 168-5224800 Oak Grove Dr Pasadena CA 91109 USA Univ Illinois NCSA Champaign IL 61820 USA Univ Illinois CSAR Champaign IL 61820 USA

Adaptive Mesh Refinement (AMR) calculations carried out on structured meshes play an exceedingly important role in several areas of science and engineering. This is so not just because AMR techniques allow us to carry out calculations very efficiently but also because they model very precisely the multi-scale fashion in which nature itself works. Many AMR applications are also amongst the most computationally intensive calculations undertaken making it necessary to use parallel supercomputers for their solution. While class library-based approaches are being attempted for parallel AMR we point out here that recent advances in the Fortran 90/95 standard and the OpenMP standard now make it possible to carry out highly parallel AMR calculations using language-based approaches, The language-based approaches offer several advantages over library-based approaches, the two principal ones being portability across parallel platforms and the best possible utilization of distributed shared memory (DSM) hardware on machines that have such hardware. They also free up the applications scientist from being constrained by the static features of a class library. The choice of Fortran also ensures maximal reuse of pre-existing Fortran 77 applications and full Fortran 77-based processing efficiency on each computational node. Our implementation of the ideas presented here in the first author's RIEMANN framework essentially permits any serial, uniform grid, stencil-based Fortran code to be turned into a parallel AMR code, In this paper we first describe our strategy for using Fortran 90 in an object-oriented fashion, This permits AMR applications to be expressed in terms of familiar abstractions that are natural to the process of solving AMR hierarchies. We then describe the OpenMP features that are useful for parallel processing of AMR hierarchies in a load balanced fashion on multiprocessors. The automatic. parallel regridding of AMR hierarchies is also described. We then present a v

关键词： parallel adaptive mesh refinement fortran 90 distributed shared memory load balancer finite difference methods

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Or-parallel Prolog on a distributed memory architecture

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JOURNAL OF LOGIC PROGRAMMING 2000年第2期43卷 173-186页

作者： Silva, F Watson, P Univ Porto DCC FC P-4150 Porto Portugal Univ Porto LIACC P-4150 Porto Portugal Univ Newcastle Upon Tyne Dept Comp Newcastle Upon Tyne NE1 7RU Tyne & Wear England

This paper discusses the design of Dorpp, an or-parallel Prolog system for distributed memory architectures, The problem of sharing the environment across a set of nodes that do not physically share memory is addressed in a novel manner by designing a Virtual shared memory (VSM) scheme to specifically meet the requirements of or-parallelism The aim is to avoid the overheads of a general VSM scheme that would provide a stricter level of memory coherence than is actually required, The paper identifies the requirements for memory coherence in or-parallel Prolog, and describes how they can be met cheaply, Simulation results are presented and analyzed in order to highlight key aspects of the system's run-time behavior. (C) 2000 Elsevier Science Inc. All rights reserved.

关键词： or-parallelism distributed shared memory memory coherency

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memory management for multi-threaded software DSM systems

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PARALLEL COMPUTING 2004年第1期30卷 121-138页

作者： Kee, YS Kim, JS Ha, S Seoul Natl Univ Sch Elect Engn & Comp Sci Seoul 151742 South Korea Korea Adv Inst Sci & Technol Div Comp Sci Taejon 305701 South Korea

When software distributed shared memory (SDSM) systems provide multithreading to exploit cluster of symmetric multiprocessors (SMPs), a challenge is how to preserve memory consistency in a thread-safe way, which is known as "atomic page update problem". In this paper, we show that this problem can be solved by creating two independent access paths to a physical page and by assigning different access permissions to them. Especially, we propose three new methods using System V shared memory inter-process communication (IPC), a new mdup0 system call, and a fork0 system call in addition to a known method using file mapping. The main contribution of this paper is to introduce various solutions to the atomic page update problem and to compare their characteristics extensively. Experiments carried out on a Linux-based cluster of SMPs and an IBM SP Night Hawk system show that the proposed methods overcome the drawbacks of the file mapping method such as high initialization cost and buffer cache flushing overhead. In particular, the method using a fork0 system call preserves the whole address space to the application. (C) 2003 Elsevier B.V. All rights reserved.

关键词： distributed shared memory atomic page update memory consistency cluster of symmetric multiprocessors

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Minimizing Context Migration in Mobile Code Offload

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2017年第4期16卷 1005-1018页

作者： Li, Yong Gao, Wei Univ Tennessee Dept Elect & Comp Sci 1520 Middle Dr Knoxville TN 37996 USA

Mobile Cloud Computing (MCC) is of particular importance to address the conflict between the increasing complexity of user applications and the limited lifespan of mobile device's battery, by offloading the computational workloads from local devices to the remote cloud. Current offloading schemes either require the programmer's annotations, which restricts its wide application;or transmits too much unnecessary data, resulting bandwidth, and energy waste. In this paper, we propose a novel method-level offloading methodology to offload local computational workload with as least data transmission as possible. Our basic idea is to identify the contexts which are necessary to the method execution by parsing application binaries in advance and applying this parsing result to selectively migrate heap data while allowing successful method execution remotely. To further improve the efficiency of such offline parsing of application binaries, our scheme also conducts one-time parsing to all the mobile OS libraries and reuses these parsing results for different user applications. We have implemented our design over the Dalvik Virtual Machine of Android OS. Our experiments and evaluation against applications downloaded from Google Play show that our approach can save data transmission significantly comparing to existing schemes.

关键词： Mobile cloud computing code offload context migration distributed shared memory virtual machine

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Improved RMS for the PC environment

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MICROPROCESSORS AND MICROSYSTEMS 1995年第10期19卷 609-619页

作者： Savic, S Tomasevic, M Milutinovic, V Gupta, A Natale, M Gertner, I ENCORE COMP CORP FT LAUDERDALE FL 33313 USA ENCORE COMP CORP MARLBOROUGH MA 01752 USA

The Reflective memory System (RMS) represents a modular bus-based architecture that belongs to the class of distributed shared memory (DSM) systems with a hardware-implemented mechanism for maintenance of memory consistency. The RMS is characterized with an update consistency mechanism for shared data in the 'mirrored' memory regions. The goal of the research presented here was to achieve a relatively large global performance and scalability improvement, using a number of relatively small particular enhancements on independent and relatively non-correlated system components (a RISC-style methodology applied to DSM). This work analyses five proposed improvements to the existing RMS. Simulation analysis using a functional simulator based on a convenient and flexible synthetic workload model was carried out, in order to evaluate each proposed idea for a wide variety of workload parameters. Besides simulation results, each presented idea is also considered from the implementational point of view. Finally, the entire fully implemented prototype design is briefly mentioned.

关键词： distributed shared memory HDL-based simulation

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Software transactional memory

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distributed COMPUTING 1997年第2期10卷 99-116页

作者： Shavit, N Touitou, D School of Mathematical Sciences Tel-Aviv University Ramat Aviv Tel-Aviv 69978 Israel IL

As we learn from the literature, flexibility in choosing synchronization operations greatly simplifies the task of designing highly concurrent programs. Unfortunately, existing hardware is inflexible and is at best on the level of a Lond-Linked/Store-Conditional operation on a single word. Building on the hardware based transactional synchronization methodology of Herlihy and Moss, we offer software transactional memory (STM), a novel software method for supporting flexible transactional programming of synchronization operations. STM is non-blocking, and can be implemented on existing machines using only a Load-Linked/Store-Conditional operation. We use STM to provide a general highly concurrent method for translating sequential object implementations to non-blocking ones based on implementing a k-word compare & swap STM-transaction. Empirical evidence collected on simulated multiprocessor architectures shows that our method always outperforms the non-blocking translation methods in the style of Barnes, and outperforms Herlihy's translation method for sufficiently large numbers of processors. The key to the efficiency of our software-transactional approach is that unlike Barnes style methods, it is not based on a costly ''recursive helping'' policy.

关键词： multiprocessor synchronization lock-free transactional memory distributed shared memory

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Adaptive software prefetching in scalable multiprocessors using cache information

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PARALLEL COMPUTING 2001年第9期27卷 1173-1195页

作者： Park, D Seong, BH Saavedra, RH Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea Univ So Calif Dept Comp Sci Los Angeles CA 90089 USA

Scalable multiprocessors present special challenges to static software prefetching because on these systems the memory access latency is not completely determined at compile time. Furthermore, dynamic software prefetching cannot do much better because individual nodes on large-scale multiprocessors would tend to experience different remote memory delays over time. A fixed prefetch distance, even when computed at run-time, cannot perform well for the whole duration of a software pipeline. Here we present an adaptive scheme for software prefetching that makes it possible for nodes to dynamically change, not only the amount of prefetching, but the prefetch distance as well. We show how simple performance data collected by hardware monitors can allow programs to observe, evaluate and change their prefetching policies. Our results show that adaptive prefetching (APF) was capable of improving performance over static and dynamic prefetching by 10%60%. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： multiprocessor distributed shared memory software prefetching adaptive prefetching adaptive execution

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A platform-independent distributed runtime for standard multithreaded java

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INTERNATIONAL JOURNAL OF PARALLEL PROGRAMMING 2006年第2期34卷 113-142页

作者： Factor, Michael Schuster, Assaf Shagin, Konstantin Technion Israel Inst Technol Dept Comp Sci IL-32000 Haifa Israel IBM Res Lab Haifa IL-31905 Haifa Israel

JavaSplit is a portable runtime environment for distributed execution of standard multithreaded Java programs. It gains augmented computational power and increased memory capacity by distributing the threads and objects of an application among the available machines. Unlike previous works, which either forfeit Java portability by using a nonstandard Java Virtual Machine (JVM) or compromise transparency by requiring user intervention in making the application suitable for distributed execution, JavaSplit automatically executes standard multithreaded Java on any heterogenous collection of Java-enabled machines. Each machine carries out its part of the computation using nothing but its local standard (unmodified) JVM. Neither the programmer nor the person submitting the program for execution needs to be aware of JavaSplit or its distributed nature. We evaluate the efficiency of JavaSplit on several combinations of operating systems, JVM implementations, and communication hardware.

关键词： distributed computing Java bytecode instrumentation distributed shared memory

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A flexible framework for consistency management

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2002年第1期14卷 33-53页

作者： Weber, S Nixon, PA Tangney, B Trinity Coll Dublin Dept Comp Sci Distributed Syst Grp Dublin 2 Ireland

Recent distributed shared memory (DSM) systems provide increasingly more support for the sharing of objects rather than portions of memory. However, like earlier DSM systems these distributed shared object systems (DSO) still force developers to use a single protocol, or a small set of given protocols, for the sharing of application objects. This limitation prevents the applications from optimizing their communication behaviour and results in unnecessary overhead. A current general trend in software systems development is towards customizable systems, for example frameworks, reflection, and aspect-oriented programming all aim to give the developer greater flexibility and control over the functionality and performance of their code. This paper describes a novel object-oriented framework that defines a DSM system in terms of a consistency model and an underlying coherency protocol. Different consistency models and coherency protocols can be used within a single application because they can be customized, by the application programmer, on a per-object basis. This allows application specific semantics to be exploited at a very fine level of granularity and with a resulting improvement in performance. The framework is implemented in JAVA and the speed-up obtained by a number of applications that use the framework is reported. Copyright (C) 2002 John Wiley Sons, Ltd.

关键词： distributed shared memory consistency model coherency protocol flexibility costumizability

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Refinement verification of the lazy caching algorithm

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ACTA INFORMATICA 2006年第3期43卷 195-222页

作者： Hesselink, Wim H. Univ Groningen Dept Math & Comp Sci NL-9700 AV Groningen Netherlands

The lazy caching algorithm of Afek et al. (ACM Trans. Program. Lang. Syst. 15, 182-206, 1993) is a protocol that allows the use of local caches with delayed updates. It results in a memory model that is not atomic (linearizable) but only sequentially consistent as defined by Lamport. In distributed Computing 12 (1999), specifying and proving sequential consistency for the lazy caching algorithm was made into a benchmark for verification models. The present note contains such a specification and proof. It provides a simulation from the implementation to the abstract specification. The concrete verification only relies on the state space and the next-state relation. All behavioural aspects are treated in theories independent of the specific algorithm. The proofs of the underlying theories and of the concrete algorithm have been verified with the proof assistant PVS.

关键词： distributed computing distributed shared memory FORMALISM (Art) ALGORITHMS BOOLEAN algebra

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