Bandwidth optimal all-reduce algorithms for clusters of workstations

We consider an efficient realization of the all-reduce operation with large data sizes in cluster environments, under the assumption that the reduce operator is associative and commutative. We derive a tight lower bound of the amount of data that must be communicated in order to complete this operation and propose a ring-based algorithm that only requires tree connectivity to achieve bandwidth optimality. Unlike the widely used butterfly-like all-reduce algorithm that incurs network contention in SMP/multi-core clusters, the proposed algorithm can achieve contention-free communication in almost all contemporary clusters, including SMP/multi-core clusters and Ethernet switched clusters with multiple switches. We demonstrate that the proposed algorithm is more efficient than other algorithms on clusters with different nodal architectures and networking technologies when the data size is sufficiently large.     

物联网数据管理研究

物联网可实现物与物、人与物的智能交互,而物联网的广泛应用则要依赖有效的数据管理。文中针对物联网中数据的特点、组成和数据的流转过程,分析了物联网数据管理所面临的问题,并在对现有数据管理技术进行研究的基础上,提出了物联网环境下基于云计算平台的数据管理框架,同时指出了在此框架下应完成的功能和实现思路。     

一种保证服务品质的存储网络性能自调节方法

给不同的存储应用分配合适的存储资源是确保存储服务品质的首要条件,使用自动管理的方式可以有效地减少管理开销,提高管理效果。提出了一种根据系统状态和服务要求自动完成物理资源的分配和调整的方法,首先提出了存储集群框架和资源映射算法,并提出了性能分析优化算法和自管理结构,另外还补充了几个实现过程中提高管理效率的方法。在存储集群的基础上,该方法的实现对存储应用是透明的。     

PID算法及参数自整定在温控系统中的实现

对PID算法及参数自整定进行了研究，介绍了PID控制算法在温控系统中的应用，给出了以ASTROM提出的极限环法为基础实现PID参数自整定的原理及软件实现。在此基础上提出了一种基于PID算法控制，且带PID参数自整定的智能温控系统的硬软件实现方法。实践证明这种方法是切实可行的。     

High performance computing on networks of workstations through the exploitation of function parallelism

Network of workstations (NOW) has become a widely accepted form of high-performance parallel computing. As in conventional multicomputers, parallel programs running on such a platform are often written in an SPMD form to exploit data parallelism. Each workstation in a NOW is treated similarly to a processing element in a multicomputer system. However, workstations are far more powerful and flexible than the processing elements in conventional multicomputers. In this paper, we discuss how workstations in a NOW can be used to exploit more parallelism in an SPMD program, especially those induced from concurrent activities.     

基于自校正的供暖系统启动控制

供暖系统最佳启动控制的重点在于准确预测预热时间,获取供暖系统的准确预热时间,并以其控制供暖系统的启动,有助于整个供暖系统能耗最小化.针对具有间歇供暖系统供暖的建筑物,分析其内部温度在外界环境和热源影响下的变化过程和规律,从热力学角度建立了间歇供暖预热过程的数学模型.基于该模型,在间歇供暖的启动控制中引入了自校正控制,并进行了仿真和实验.结果表明,将自校正控制用于供暖系统的启动控制效果较好,能够节约能源.     

面向海量非结构化数据的非关系型存储管理机制

针对传统的关系数据存储系统性能不足、容错性差,无法适应海量非结构化数据管理的问题,提出一种高性能、高可用非关系型存储管理机制。首先,设计了良好的用户访问服务接口,通过高效的一致性哈希算法支持数据分发到多个存储节点;其次,采用可配置的数据副本机制改善存储系统的可用性;最后,提出查询故障处理机制,用以提升存储系统的容错性,避免节点失效导致服务中断问题。实验结果表明,在不同规模用户负载下,新的存储系统的并发访问请求能力和传统的文件系统、关系数据库相比,分别提升了30%和50%;同时,在合理响应时间内,故障状态下的存储系统的可用性损失小于14%。因此,该机制适用于海量非结构化数据的高效存储管理。     

Efficient scheduling of MPI applications on networks of workstations

The availability of a large number of workstations connected through a network can represent an attractive option for high-performance computing for many applications. The message-passing interface (MPI) software environment is an effort from many organisations to define a de facto message-passing standard. In other words, the original specification was not designed as a comprehensive parallel programming environment and some researchers agree that the standard should be preserved as simple and clean as possible. Nevertheless, a software environment such as MPI should have somehow a scheduling mechanism for the effective submission of parallel applications on network of workstations. This paper presents an alternative lightweight approach called Selective-MPI (S-MPI), which was designed to enhance the efficiency of the scheduling of applications on an MPI implementation environment.     

基于群机系统的并行程序的最大加速比计算

加速比是并行程序的重要指标之一。在大多数并行系统中,在数据规 模确定的情况下,程序的加速比随节点工作站的增加而增加,但是大多数群机 系统的节点工作站是共享物理传输介质的,这使得许多并行程序的加速比在节 点机数目超过某一个值之后会随着节,点机的增加而减少。本文通过对群机系统 上并行程序执行时间的分析,论述了在数据规模确定的情况下,程序能够获得 的最大加速比和最短的计算时间,以及获得这个加速比和计算时间的节点机个 数。     

基于大数据的电力企业财务数据管理系统研究

当前,在各类电力生产经营财务数据管理活动中产生的海量、高频数据,具有实时性、突发性、易失性、无序性、无限性等特征。为解决电力企业接入的财务数据的不一致、不规范的问题,以及如何快速从这些海量高频数据中获取有价值的信息、提高数据资产带来的经济效益和数据管理效率,本文在分析目前电力大数据应用现状的基础上,构建了基于大数据的电力企业财务数据管理系统,同时从基于NoSQL的大数据存储管理、基于Hadoop的财务大数据预处理以及财务大数据分析挖掘算法3个方面详细描述了电力企业财务数据管理的关键技术,大幅提升了电力企业财务数据的管理效率和准确性,为在线决策分析提供理论依据及基础技术支撑。     

模糊自校正控制器在多温区温度控制系统中的应用

本文介绍了一种模糊自校正控制器，它能对一个系统中不同温区的温度进行精确控制。作者给出了该模糊控制系统的结构，着重讨论了补偿系数与调整因子的计算与确定方法。实验表明，该控制器具有良好的自适应性和动、静态特性。     

A generalized histogram clustering scheme for multidimensional image data

A clustering procedure called HICAP (HIstogram Cluster Analysis Procedure) was developed to perform an unsupervised classification of multidimensional image data. The clustering approach used in HICAP is based upon an algorithm described by Narendra and Goldberg to classify four-dimensional Landsat Multispectral Scanner data. HICAP incorporates two major modifications to the scheme by Narendra and Goldberg. The first modification is that HICAP is generalized to process up to 32-bit data with an arbitrary number of dimensions. The second modification is that HICAP uses more efficient algorithms to implement the clustering approach described by Narendra and Goldberg.(¹) This means that the HICAP classification requires less computation, although it is otherwise identical to the original classification. The computational savings afforded by HICAP increases with the number of dimensions in the data.     

多维数据的Z-Ordering存储映射算法及其缓存调度优化

多维数据以线性形式在存储系统中进行访问操作,二维及以上维度空间中的相邻节点被不同的映射算法映射到一维空间的不相邻位置。高维空间中进行相邻节点访问时,其一维存储映射位置有着不同的访问距离和访问延迟。提出了基于空间填充曲线Z-Ordering的存储映射方法及其访问距离的度量指标,并和常规优先算法进行了对比,发现能更好地将高维相邻的数据节点簇集到一维存储位置,加强了局部性。调整缓存空间中用于预取的空间大小,可以利用增强的局部性,提高了缓存命中率。实验结果表明,改善了多维数据的访问速度,优化了系统性能。     

Self-tuning and stable adaptive control of a batch polymerization reactor

Two adaptive control techniques are evaluated by application to a realistic mathematical model of a suspension polyvinyl chloride (PVC) reactor. Both techniques, the self-tuning regulator and a globally stable adaptive control algorithm, prove to be very robust and give excellent control of the temperature or the rate of conversion in the PVC reactor by manipulating the heat removal rate from the reactor jacket. Satisfactory regulation and setpoint changes in the temperature and the conversion rate are obtained in each case even in the presence of measurement noise and highly nonlinear reactor dynamics. The performance of the two adaptive techniques is compared with the performance of a classical, PID controller. The adaptive controllers are shown to always outperform the PID controller.     

随机模式匹配并行算法在工作站机群上的实现

对随机模式匹配算法进行了改进,并根据MPICH并行编程环境中任务间通信的特点,设计了一种基于MPICH的改进的随机模式匹配并行算法。根据运行在COW（工作站机群）上的进程数目将文本串进行重叠划分,每个进程完成一个文本子串的模式匹配。实验结果表明,该改进的随机模式匹配并行算法有效地加快了模式匹配的速度,提高了工作站机群的资源利用率。     

Coupling hundreds of workstations for parallel molecular sequence analysis

We present a highly scalable approach to distributed parallel computing on workstations in the Internet which provides significant speed-up to molecular biology sequence analysis. Recent developments show that smaller numbers of workstations connected via a local area network can be used efficiently for parallel computing. This work emphasizes scalability with respect to the number of workstations employed. We show that a massively parallel approach using several hundred workstations, dispersed over all continents, can successfully be applied for solving problems with low requirements on communication bandwidth. We calculated the optimal local alignment scores between a single genetic sequence and all sequences of a genetic sequence database using the ssearch code that is well known among molecular biologists. In a heterogeneous network with more than 800 workstations this job terminated after several minutes, in contrast to several days it would have taken on a single machine.     

基于Web的远程集群监控系统的设计与实现

集群系统的商品化部件构成特点在具有高性价比优点的同时,也带来了可用性和可管理性差的缺点,因此集群系统的监控就变得特别重要。该文结合国家高性能计算中心(西安)的Linux集群系统给出了一种基于Web的集群监控系统的体系结构框架以及实现策略,详细介绍了数据采集、信息收集和存储以及状态的可视化各个模块的具体实现,基于WEB的实现策略使该系统具有平台无关性和监控远程性的优点。     

基于自适应模糊控制的Web带宽区分服务

基于线程/进程分配的Web区分服务策略仅仅关注连接延迟,而在服务器带宽受限的情况下,由于处理延迟成为客户端总延迟的主导部分,因此区分效果很差.提出的基于带宽调节的区分服务策略,通过两级自适应模糊控制,调整服务于不同优先级请求的虚拟主机的带宽配额,从而控制处理延迟,实现比例延迟保证.经稳定性分析与实验验证,这种方法取得了良好的效果,相对于静态模糊控制,其延迟比与期望值的方差减少了40%.     

Auto-CFD-NOW: A pre-compiler for effectively parallelizing CFD applications on networks of workstations

Computational Fluid Dynamics (CFD) applications are highly demanding for parallel computing. Many such applications have been shifted from expensive MPP boxes to cost-effective Networks of Workstations (NOW). Auto-CFD-NOW is a pre-compiler that transforms Fortran CFD sequential programs to efficient message-passing parallel programs running on NOW. Our work makes the following three unique contributions. First, this pre-compiler is highly automatic, requiring a minimum number of user directives for parallelization. Second, we have applied a dependency analysis technique for the CFD applications, called analysis after partitioning. We propose a mirror-image decomposition technique to parallelize self-dependent field loops that are hard to parallelize by existing methods. Finally, traditional optimizations of communication focus on eliminating redundant synchronizations. We have developed an optimization scheme which combines all the non-redundant synchronizations in CFD programs to further reduce the communication overhead. The Auto-CFD-NOW has been implemented on networks of workstations and has been successfully used for automatically parallelizing structured CFD application programs. Our experiments show its effectiveness and scalability for parallelizing large CFD applications. This work is supported in part by the China National Aerospace Science Foundation, and by the U.S. National Science Foundation under grants CCR-9812187, CCR-0098055, CCF-0325760, CCF 0514078, and CNS 0549006.