并行循环的乐观自调度模式

并行循环的自调度模式是研究以最小运行开销和最佳负载平衡将循环体分布到各处理器上做并行计算，早期的自调度模式基于悲观的思想，认为并行循环是非均匀分布的，因此为克服负载不平衡，循环体被分割成大量任务包，因而导致较大的调度开销，本文提出一类乐观自调度模式，假定循环是均匀分布的，按现有处理器数对循环做初始划分可取得较好的负载平衡，同时，乐观模式还提出克服初始划分不良引起负载不平衡的一种简单且有效的方法，模     

PC机群上共享存储与消息传递的比较

共享存储和消息传递是目前两种主流的并行编程模型.一般认为,消息传递的可编程性不及共享存储友好.OpenMP是目前共享存储编程的实际工业标准.机群OpenMP系统在机群上提供了OpenMP编程环境,具有易编程和可扩展的特点,但是其性能如何一直是关注的热点.以机群OpenMP系统OpenMP/JIAJIA和典型的消息传递系     

Comparing Processor Allocation Strategies in Multiprogrammed Shared-Memory Multiprocessors

Small-scale shared-memory multiprocessors are commonly used in a workgroup environment where multiple applications, both parallel and sequential, are executed concurrently while sharing the processors and other system resources. To utilize the processors efficiently, an effective allocation strategy is required. In this paper, we use performance data obtained from an SGI multiprocessor to evaluate several processor allocation strategies when running two parallel programs simultaneously. We examine gang scheduling (coscheduling), static space-sharing (space partitioning), and a dynamic allocation scheme called loop-level process control (LLPC) with three different dynamic allocation heuristics. We use regression analysis to quantify the measured data and thereby explore the relationship between the degree of parallelism of the application, specific system parameters (such as the size of the system), the processor allocation strategy, and the resulting performance. This study shows that dynamically partitioning the system using LLPC or similar heuristics provides better performance for applications with a high degree of parallelism than either gang scheduling or static space-sharing.     

共享存储多处理机系统在并行程序设计模式下的处理机分配法

该文在假定的系统结构和编程模型之上,分析了几种已有的基于共享存储的多处理机系统的处理机分配方法及其缺陷,提出了一种改进的方法,并对其实现进行了探讨。     

自适应区间配置在关联规则并行采掘中的作用

现行的采掘关联规则的并行算法基于经典的层次算法.该方法在每一次重复扫描数据库时都需要一次同步,这种同步运算对于共享内存多处理器并行机来说极大地降低了采掘性能,这种低效主要源于对共享的I/O通道的竞争.该文提出了在共享内存多处理机上采掘关联规则的异步算法APM.在APM中,所有参与计算的处理器能独立地产生备选集和计算支持度.而且,APM所需的扫描数据库的次数比层次方法所需的更少.该文还提出了一种增强APM的技术,使得该算法的性能对于数据分布更具有鲁棒性.文中实现了APM的变种算法,还实现了Apriori的并行版本Count Distribution算法.在SGI Power Challenge SMP并行机上,进行了性能分析,结果表明所提出的异步算法APM具有更好的性能和可扩展性.     

A Distributed Shared-Memory System on a Workstation Cluster Using Fast Serial Links

In this paper, a fast serial link, Serial Transparent Asynchronous First-in First-out Link (STAFF-Link), is introduced. Using such links, we construct a parallel processing system based on a workstation cluster. The workstation cluster implements a distributed sharedmemory mechanism for inter-process communication using a software controlled cache using a STAFF-Link router board. The board has a chained multicast capability with which we have implemented efficient invalidation protocol based on Eager Release Consistency (ERC) model in the DSM system. Performance results on several application programs from the SPLASH2 benchmark suites have been measured.     

针对特普利茨线性系统的多级并行算法

利用并行体系结构中不同层次级别的内存和计算单元,提出一种求解对称结构化特普利茨线性系统的多级并行算法。通过数学推导将特普利茨线性系统转换成柯西式线性系统,利用消息传递接口和开放多平台共享内存并行程序设计工具实现该算法,并通过实验验证其可行性。     

Efficient Integration of Compiler-Directed Cache Coherence and Data Prefetching

Cache coherence enforcement and memory latency reduction and hiding are very important and challenging problems in the design of large-scale distributed shared-memory (DSM) multiprocessors. We propose an integrated approach to solve these problems through a compiler-directed cache coherence scheme called the Cache Coherence with Data Prefetching (CCDP) scheme. The CCDP scheme enforces cache coherence by prefetching the potentially stale references in a parallel program. It also prefetches the non-stale references to hide their memory latencies. To optimize the performance of the CCDP scheme, some prefetch hardware support is provided to efficiently handle these two forms of data prefetching operations. We also developed the compiler techniques utilized by the CCDP scheme for stale reference detection, prefetch target analysis, and prefetch scheduling. We evaluated the performance of the CCDP scheme via execution-driven simulations of several numerical applications from the SPEC CFP95 and the Perfect benchmark suites. The simulation results show that the CCDP scheme provides significant performance improvements for the applications studied, comparable to that obtained with a full-map hardware cache coherence scheme.     

基于SMP集群系统的并行编程模式研究与分析

并行计算技术是计算机技术发展的重要方向之一,SMP与集群是当前主流的并行体系结构。当前并行程序设计方法主要采用基于消息传递模型的MPI和基于共享存储模型的OpenMP,两种编程模式各有特点和适用范围。对SMP集群以及MPI和OpenMP的特点进行了分析,介绍了在SMP集群系统中利用MPI和OpenMP混合编程的可行性方法。