John Ousterhout Partitioning and Cooperation in a Distributed Multiprocessor Operating System: MEDUSA Degree Type: Ph.D. in Computer Science Advisor(s): Nico Habermann Graduated: May 1980 Abstract: This dissertation is an analysis of the design of Medusa, an operating system with a highly distributed control structure that runs on the Cm* multimicroprocessor. In order to gain an understanding of how to exploit distributed hardware, the system's structure was allowed to derive directly from the constraints of the underlying machine. The Cm* hardware is distributed, yet extremely flexible in the kinds of interprocessor communication it permits. Thus Medusa's structure arose from a consideration of two issues: partitioning and cooperation. How should the system be partitioned in order to enhance its modularity and make use of the distributed hardware? How should the separate subunits communicate so as to function together in a robust way as a single logical entity? The resulting system combines several structural features that make it unique among existing operating systems. Thesis Committee: Nico Habermann Nico Habermann, Head, Computer Science Department