Browsing by Author "Speight, William Evan"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Efficient runtime support for cluster-based distributed shared memory multiprocessors
    (1998) Speight, William Evan; Bennett, John K.
    Distributed shared memory (DSM) systems provide a shared memory programming paradigm on top of a physically distributed network of computers. The DSM system removes the necessity for programmers to move data explicitly between processors. The principle challenge in the development of an efficient DSM system lies in reducing the amount of communication necessary to maintain coherence to an absolute minimum. This thesis presents Brazos, a DSM system for use in an environment of symmetric multiprocessor (SMP) personal computers that are networked together by industry-standard 100 Mbps FastEthernet. Brazos is distinguished by its use of application-level multithreading, selective multicast, adaptive runtime mechanisms, and a unique performance history mechanism. Through the detailed analysis of twelve scientific programs, we show that Brazos outperforms the current state-of-the-art software DSM system by an average of 83%, and outperforms a version of the same DSM system that has been altered to take advantage of SMP personal computers by an average of 32%. Our results indicate that networks of commodity personal computers using available PC networks and operating systems can perform comparably on a wide variety of scientific applications to more traditional networks of high-end engineering workstations.
  • Thumbnail Image
    Item
    ParaView: Performance debugging through visualization of shared data
    (1994) Speight, William Evan; Bennett, John K.
    Performance debugging is the process of isolating and correcting performance problems in an otherwise correct parallel program. Problems not immediately visible to the parallel programmer often lead to poor application performance. This thesis describes the design, implementation, and use of ParaView, a tool to locate performance inefficiencies in programs written for shared-memory multiprocessors. ParaView supplies an intuitive, graphical interface based upon the X-windows system. ParaView aids parallel applications programmers in uncovering performance bugs relating to poor cache performance, load balancing, false sharing, and inefficient synchronization. Eleven parallel programs have been analyzed using ParaView, and performance limitations in five of these were improved. Reductions in overall execution times range from 25% to 86% for sixteen processor simulations. Our experience demonstrates that ParaView facilitates parallel program performance debugging by reducing the amount of time required to uncover and correct performance problems relating to poor data partitioning, false sharing, contention for shared data constructs, and unnecessary synchronization.