并行程序设计环境的研究

MPI（Message Passing Interface）是目前一种比较著名的应用于并行环境的消息传递标准。MPICH是MPI1．2标准的一个完全实现，也是应用范围最广的一种并行及分布式环境。MPICH除包含MPI函数库之外，还包含了一套程序设计以及运行环境．本文将简要介绍如何应用MPICH的Windows版本，建立一个基于Windows的并行程序设计及运行环境．     

The Effect of Process Topology and Load Balancing on Parallel Programming Models for SMP Clusters and Iterative Algorithms

This article focuses on the effect of both process topology and load balancing on various programming models for SMP clusters and iterative algorithms. More specifically, we consider nested loop algorithms with constant flow dependencies, that can be parallelized on SMP clusters with the aid of the tiling transformation. We investigate three parallel programming models, namely a popular message passing monolithic parallel implementation, as well as two hybrid ones, that employ both message passing and multi-threading. We conclude that the selection of an appropriate mapping topology for the mesh of processes has a significant effect on the overall performance, and provide an algorithm for the specification of such an efficient topology according to the iteration space and data dependencies of the algorithm. We also propose static load balancing techniques for the computation distribution between threads, that diminish the disadvantage of the master thread assuming all inter-process communication due to limitations often imposed by the message passing library. Both improvements are implemented as compile-time optimizations and are further experimentally evaluated. An overall comparison of the above parallel programming styles on SMP clusters based on micro-kernel experimental evaluation is further provided, as well.     

A Parallel Implementation of the Katsevich Algorithm for 3-D CT Image Reconstruction

Yu and Wang [1, 2] implemented the first theoretically exact spiral cone-beam reconstruction algorithm developed by Katsevich [3, 4]. This algorithm requires a high computational cost when the data amount becomes large. Here we study a parallel computing scheme for the Katsevich algorithm to facilitate the image reconstruction. Based on the proposed parallel algorithm, several numerical tests are conducted on a high performance computing (HPC) cluster with thirty two 64-bit AMD-based Opteron processors. The standard phantom data [5] is used to establish the performance benchmarks. The results show that our parallel algorithm significantly reduces the reconstruction time, achieving high speedup and efficiency.     

基于PROFIBUS的快锻机组网络系统

杜亚宁（1973-），女，助理工程师，主要从事设备的自动化控制技术及相关管理工作，电话：029-86514525，E-Mail：dyn@c-wst.com     

MPI全互换通信的性能优化

MPI全互换操作是集群计算机上进行仿真计算时常用的通信操作之一,用于各计算节点间交换上一步骤的中间计算结果。由于全互换通信的密集多对多通信容易产生接收端的阻塞从而增加通信延时,因此通过形成环状的多次规律且有序的通信过程来优化全互换通信操作过程,在大数据量的全互换通信中可以获得明显的性能提升。     

使用MPI的并行I/O实现及性能分析

论文讨论了并行环境中I/O的基本方法——串行I/O方法和并行I/O方法,并使用MPI-1及MPI-2对这两种方法进行了实现。分析了不同的实现方法对I/O带宽产生的影响。通过理论分析和实验表明,基于MPI-2的并行I/O实现方法与其它I/O实现方法相比,可得到更高的I/O带宽,是解决I/O性能问题的有效途径。     

基于InfiniBand网络的MPI实现与分析

近年来,利用普通PC和高速网络搭建集群已经成为构建高性能计算环境的一种趋势。虽然InfiniBand在高性能计算领域还是相对比较新的技术,但是它的丰富特性使得它在高性能领域所占份额日趋扩大。InfiniBand Architecture(IBA)这种工业标准的主要设计思想是采用支持多并发链接的“转换线缆”技术提供高性能和高可靠性.这篇文章介绍了InfiniBand的体系结构和在InfiniBand上实现MPI的有关技术。最后在集群环境中,用MPI对InfiniBand网络的各项性能指标进行了测试。     

Maximum Likelihood Estimation Using Parallel Computing: An Introduction to MPI

The computational difficulty of econometric problems has increased dramatically in recent years as econometricians examine more complicated models and utilize more sophisticated estimation techniques. Many problems in econometrics are `embarrassingly parallel' and can take advantage of parallel computing to reduce the wall clock time it takes to solve a problem. In this paper I demonstrate a method that can be used to solve a maximum likelihood problem using the MPI message passing library. The econometric problem is a simple multinomial logit model that does not require parallel computing but illustrates many of the problems one would confront when estimating more complicated models.     

Linux机群系统并行程序调试器的设计与实现

介绍了在基于Linux的机群系统中，并行程序调试工具XBUSTER的设计与实现，包括调试器的基本结构及在实现时所涉及的一些关键技术。XBUSTER具有一般调试器的基本调试功能，可以调试用C／Fortran语言编写的PVM或MPI，对并行程序的各个进程能够单独或同时进行调试，并且能够实现进程的动态调试。该系统已在运行Linux系统的清华集群计算机系统上运行，具有较好的实用性。     

Scalability of hybrid programming for a CFD code on the Earth Simulator

The Earth Simulator (ES) is an SMP cluster system. There are two types of parallel programming models available on the ES. One is a flat programming model, in which a parallel program is implemented by MPI interfaces only, both within an SMP node and among nodes. The other is a hybrid programming model, in which a parallel program is written by using thread programming within an SMP node and MPI programming among nodes simultaneously. It is generally known that it is difficult to obtain the same high level of performance using the hybrid programming model as can be achieved with the flat programming model.

In this paper, we have evaluated scalability of the code for direct numerical simulation of the Navier–Stokes equations on the ES. The hybrid programming model achieves the sustained performance of 346.9 Gflop/s, while the flat programming model achieves 296.4 Gflop/s with 16 PNs of the ES for a DNS problem size of 256³. For small scale problems, however, the hybrid programming model is not as efficient because of microtasking overhead. It is shown that there is an advantage for the hybrid programming model on the ES for the larger size problems.