A Decentralized Computational Infrastructure for Grid-Based Parallel Asynchronous Iterative Applications

Parallel asynchronous iterative algorithms relax synchronization and communication requirements, and can potentially extend Desktop Grids beyond embarrassingly parallel applications to support a broader class of parallel iterative applications. This paper presents the design and implementation of CometG, a decentralized (peer-to-peer) computational infrastructure that extends Desktop Grid environments to support these applications. CometG provides a decentralized and scalable tuple space, efficient communication and coordination support, and application-level abstractions that can be used to implement Desktop Grid applications based on parallel asynchronous iterative algorithms using the master-worker/BOT paradigm. The deployment and evaluations of CometG and a CometG-based application in a wide-area environment using the PlanetLab [7] test bed, as well as a campus network are presented.     

面向特定应用的计算加速器虚拟化

近年来,专用指令集处理器(application specific instruction set processor,ASIP)在嵌入式系统中得到了越来越广泛的应用.这些ASIP提供了面向某个领域定制硬件计算加速器的功能.通过利用加速器提供的扩展指令,可以大幅提升ASIP面向领域的处理能力.然而,这些计算加速器只能加速那些在编译时加入了扩展指令的应用程序.对于在编译时没有加入扩展指令的应用而言,得不到任何性能提升.利用软件动态二进制翻译来解决这一问题,即将计算加速器虚拟化.与传统的静态编译方法所不同的是,以动态虚拟化方式利用计算加速器面临许多新的问题.针对这些问题,提出了一系列解决方法,并用实验加以验证.     

轨道交通联锁领域特定语言的形式化

作为轨道交通系统的核心子系统之一,对联锁系统进行形式化建模与分析,是保证其安全性的重要手段.形式化建模需要领域知识和形式化知识的结合,由于形式化知识难以掌握,领域专家在建模整个过程中都需要形式化专家的帮助.为了解决这个问题,针对联锁系统的故障随机性、行为实时性、构件可重用的特点,提出设计联锁领域特定语言IS-DSL描述具体的联锁系统的参数,并基于随机混成自动机模板自动生成联锁系统的形式化模型,以进一步在此基础上进行安全分析.首先对联锁系统模型进行分析,根据不同案例设计其领域特定语言;其次,确定联锁系统的系统模型模板,包括环境构件模板和控制器模板,并举例抽取其随机混成自动机模板;在模板基础上定义系统模型生成过程,让领域专家可以通过领域特定语言,输入参数自动生成具体的随机混成自动机系统模型;最后以某站联锁系统为例,展示了基于模板的具体系统模型的生成过程,并通过基于系统模型的事故预测分析,证明了该方法的可行性与有效性.     

基于Drools的领域专用语言应用研究

首先介绍了Drools规则引擎和领域专用语言DSL的基本概念,然后通过实例说明了DSL以类自然语言的方式来构建业务层代码,详细阐述了领域专用语言在Drools中的应用来说明它的优点。通过DSL的应用不仅降低了业务逻辑与应用程序的耦合度,而且能以更好的方式来处理业务需求和数据模型的变化,便于系统的维护。     

Automatic Task-Based Code Generation for High Performance Domain Specific Embedded Language

Providing high level tools for parallel programming while sustaining a high level of performance has been a challenge that techniques like Domain Specific Embedded Languages try to solve. In previous works, we investigated the design of such a DSEL—NT\(^2\)—providing a Matlab -like syntax for parallel numerical computations inside a C++ library. In this paper, we show how NT\(^2\!\) has been redesigned for shared memory systems in an extensible and portable way. The new NT\(^2\!\) design relies on a tiered Parallel Skeleton system built using asynchronous task management and automatic compile-time taskification of user level code. We describe how this system can operate various shared memory runtimes and evaluate the design by using two benchmarks implementing linear algebra algorithms.     

基于领域专用语言的应用软件自动生成

在领域专用语言、领域专用库和应用产生器的基础上,提出一种自动生成应用软件的设计框架,详细论述了该设计框架的设计原理和具体的实现过程。该设计框架由三级组成:首先设计一种该应用领域的领域专用语言,它将该应用领域的应用系统作为领域分析的对象,语言上集数据、功能和界面于一体;其次实现该应用领域的一个领域专用库,它提供应用系统级的复用;在这两者的基础上,最后实现一个集工具、语言和库于一体的可视化应用产生器,用它可以快速地开发完整的应用软件。已成功地将该设计框架运用于GIS应用系统领域。用应用产生器开发应用软件,不仅加强了应用系统开发过程的集成,提高了软件的开发效率,实现了软件过程的复用,而且达到了系统级的软件复用。     

Log File Formats for Parallel Applications: A Review

The objective of this paper is the review of the log file formats that allow the performance visualization of parallel applications based on the usage of message passing interface (MPI) standard. These file formats have been designed by the LANS (Laboratory for Advanced Numerical Software) group of the Argonne National Laboratory and they are distributed together with the corresponding viewers as part of the MPE (multipurpose environment) library of the MPICH implementation of the MPI. The formats studied in this paper is the ALOG, CLOG, SLOG1 and SLOG2 file formats—the formats are studied in chronological order and the main features of their structures are presented.     

CC$:一种面向分布式众核平台的并行编程语言

CC$是一种并行编程语言,目的是解决分布式众核并行计算机的编程困难。CC$的编程模型以Multi BSP 模型为基础,将分布式众核并行计算机的硬件架构抽象为3层。数据按照存储的层次和共享范围分为5类,以便在不 同层次上提供共享。LL$还提出一类虚拟指令来解决不同层次之间的数据交换,实现数据访问的逻辑化描述。并行 程序按照3层Multi BSP超步嵌套执行。CC$具有统一的编程风格、内建的多层会共地址空间、数据访问请求的表达 式描述和数据传输编译优化4大特点。测试表明,CC$程序的运行效率高,易学易用,大幅地缩短了开发周期。     

一个面向网络并行环境的需求规约语言

提出了一个面向网络并行环境的需求规约语言ＯＯＲＳＬ。ＯＯＲＳＬ支持面向对象的分析方法,可以定义并行成分一进程,可以使用前后断言来表达用户的功能需求,允许将非经和半形式化的需求定义嵌入形式化的需求定义中。因此,ＯＯＲＳＬ语言是一个半形式化的语言,它为网络并行环境下的软件自动化和软件形式化开发提供了支持介绍了ＯＯＲＳＬ的设计思想和主要语法成分。给出了一个实例。     

A Novel Parallel Manipulator Architecture for Manufacturing Applications

This paper proposes a new type of a six-degree-of-freedom parallelmanipulator with six prismatic legs for manufacturing applications. Eachleg is connected to a base by universal and prismatic joints, and to amoving platform by spherical joints. Based on the complete kinematicsmodel developed in this paper, analytical expressions are derived forthe displacement, velocity and accelerations. The dynamic equations ofthe manipulator are obtained from the kinematic model using the NOCmethod. The implementation of the model in an algorithm is shown throughsimulations to compute the required actuator forces for a sampletrajectory.     

一种用计算域分解的等几何分析并行化方法

提出一种按照计算域分解的并行化方法来构建等几何分析的刚度矩阵和右侧向量.将计算域分解成为若干个不相交的子区域,然后为每个区域分配一个处理器,所有处理器并行进行子区域上面的计算,所有处理器完成子区域的计算以后,使用一个快速的归并算法完成线性系统的装配.实验表明,本文提出的方法在8核的机器上可以达到6.46的加速比,能够在4秒左右的时间计算680万个矩阵元素个数.使用Intel MKL稀疏求解器来求解线性系统,本文的等几何分析求解器能够在大约10秒的时间内求解52万的自由度,本文的方法比ISOGAT速度要快上万倍.     

FORTRAN M - A Language for Modular Parallel Programming

FORTRAN M is a small set of extensions to FORTRAN 77 that supports a modular approach to the design of message-passing programs. It has the following features. (1) Modularity. Programs are constructed by using explicitly declared communication channels to plug together program modules called processes. A process can encapsulate common data, subprocesses, and internal communication. (2) Safety. Operations on channels are restricted so as to guarantee deterministic execution, even in dynamic computations that create and delete processes and channels. Channels are typed, so a compiler can check for correct usage. (3) Architecture Independence. The mapping of processes to processors can be specified with respect to a virtual computer with size and shape different from that of the target computer. Mapping is specified by annotations that influence performance but not correctness. (4) Efficiency. FORTRAN M can be compiled efficiently for uniprocessors, shared-memory computers, distributed-memory computers, and networks of workstations. Because message passing is incorporated into the language, a compiler can optimize communication as well as computation.     

并行面向对象语言综述

近年来,面向对象语言的并行化技术取得了许多重要进展.以Mentat,CC++,pC++,HPC++和ICC++等几个典型系统为代表,从并行执行模型、语言并行设施、优化技术和运行时支持等几个方面归纳、总结了近年来这些语言和编译器支持并行的新技术.同时,还给出了对这些技术的分析和评价,总结了需要进一步研究和解决的问题.     

A Data Parallel Scientific Modeling Language

The data parallel meta language (DPML) and its associated Fortran source code rewriter (DP77) support architecture independent, high performance climate and weather prediction models. The language allows the data domains over which a program operates, the communication patterns required between elements of those data domains, and some or all of the calculations of a program to be expressed at a very high level. DPML uses explicit data parallelism to express the inherent parallelism of the models, with the result that programs are easily compilable into target machine code. DP77 uses information from the DPML program to translate Fortran routines into the host specific Fortran form required for their parallel execution within the model. This paper describes the general strategy behind the development of DPML, discusses its language features using examples drawn from climate modelling, and provides details of the mechanism it uses for incorporating Fortran into data parallel programs. Encouraging results are reported for DPML versions of the standard weather benchmark models executing on vector, SIMD, and MIMD (shared memory) machines. While the paper is set within the framework of climate modelling, the technique has obvious wider implications.     

ZENTURIO: A Grid Service-Based Tool for Optimising Parallel and Grid Applications

ZENTURIO [R. Prodan and T. Fahringer, ZENTURIO: A Grid Middleware-based Tool for Experiment Management of Parallel and Distributed Applications, Journal of Parallel and Distributed Computing, 2003. http://authors.elsevier.com/sd/article/S0743731503001977 (to appear)] is a semi-automatic experiment management tool for performance and parameter studies of parallel and distributed applications on cluster and Grid architectures. ZENTURIO has been designed as an Open Grid Services Architecture (OGSA) – compliant Grid application built on top of standard Web and Grid services technologies. In this paper we first comparatively present various issues from our transition to an Open Grid Services Infrastructure (OGSI) – compliant prototype. Then we introduce a generic framework for solving NP-complete optimisation problems for parallel and Grid applications. We present a case study on high throughput scheduling for large sets of computational tasks on the Grid using genetic algorithms. Our algorithm has a complexity of and delivers a fivefold improvement in solution over 500 generations in a Grid with uniformly distributed computational resources. This research is supported by the Austrian Science Fund as part of the Aurora project under contract SFBF1104.     

面向垂直领域的阅读理解数据增强方法

阅读理解问答系统是利用语义理解等自然语言处理技术,根据输入问题,对非结构化文档数据进行分析,生成一个答案,具有很高的研究和应用价值。在垂直领域应用过程中,阅读理解问答数据标注成本高且用户问题表达复杂多样,使得阅读理解问答系统准确率低、鲁棒性差。针对这一问题,该文提出一种面向垂直领域的阅读理解问答数据的增强方法,基于真实用户问题,构造阅读理解训练数据,一方面降低标注成本,另一方面增加训练数据多样性,提升模型的准确率和鲁棒性。该文用汽车领域数据对本方法进行实验验证,其结果表明,该方法对垂直领域中阅读理解模型的准确率和鲁棒性均得到有效提升。     

面向特定领域的汉语句法主干分析

本文提出了一种面向特定领域的汉语句法主干分析方法。该方法中包括浅层句法分析、模板匹配两个关键环节,形成用模板表示的句法主干。在浅层句法分析中,本文使用了级联的隐马尔可夫模型进行了短语的归并;而后以已有的汉语句子模板为基础,进行模板匹配以达到句法主干分析的目标。在针对体育新闻领域语料的开放测试中,模板匹配的精确率和召回率分别达到了98.04%和81.43% ,句子级的精确率和召回率分别达到了96.97%、84.85% ,实验表明该方法在特定领域是有效的。     

基于领域模型的网页搜索排序算法

通用搜索引擎在检索过程中会出现查询结果与关键词所属领域无关的主题漂移现象.本文提出了面向特定领域的网页重排序算法-TSRR(Topic Sensitive Re-Ranking)算法,从一个新的视角对主题漂移问题加以解决. TSRR算法设计一种独立于网页排序的模型,用来表示领域,然后建立网页信息模型,在用户检索过程中结合领域向量模型和网页信息模型对网页搜索结果进行重排序.在爬取的特定领域的数据集上,以用户满意度和准确率为标准进行评估,实验结果表明,本文中提出的TSRR算法性能优异,比经典的基于Lucene的排序算法在用户满意度上平均提高17.3%,在准确率上平均提高41.9%.