Our program of research combines three related themes: the development of techniques for studying computer system performance; the use of these techniques to gain insight about significant computer system design issues; and the design and implementation of computer systems exploiting these insights.
The current focus of our attention, not surprisingly, is parallel computer systems. Our objective is to develop tools and techniques for building high-performance parallel programs and parallel systems.
One major area of recent work concerns scheduling techniques for multiprogrammed multiprocessors. This work has involved analysis (studying the properties of classes of disciplines), simulation (investigating specific disciplines using ``generic'' workloads), and experiment (using a scheduling ``testbench'' built on the department's Sequent Symmetry-81 system, and more recently a direct implementation of these ideas on the KSR-1).
Another area of work concerns communication scheduling in distributed memory parallel supercomputers, with the goal of reducing the runtime overhead of message passing programs. More broadly, we have several projects that are considering runtime support for targeted classes of scientific applications that are ``big enough'' to be interesting but ``small enough'' to have common characteristics that can be exploited to achieve improved performance without burdening the programmer.
A third area involves the use of ``imprecision'' for continuous media applications. Imprecision is a programming concept in which multiple versions of a computation are provided (or multiple parameterizations of an algorithm exist) that differ in the quality of the results provided and the amount of time required to obtain them. We are investigating system and application designs to exploit imprecision in building robust continuous media applications.
Our work in computer system performance is closely related to our work (with Brian Bershad and Hank Levy) in system support for advanced architectures.
Principal Investigators: Lazowska, Zahorjan