Distributed shared memory for virtual environments

Bibliography: leaves 71-77.This work investigated making virtual environments easier to program, by designing a suitable distributed shared memory system. To be usable, the system must keep latency to a minimum, as virtual environments are very sensitive to it. The resulting design is push-based and non-consistent. Another requirement is that the system should be scaleable, over large distances and over large numbers of participants. The latter is hard to achieve with current network protocols, and a proposal was made for a more scaleable multicast addressing system than is used in the Internet protocol. Two sample virtual environments were developed to test the ease-of-use of the system. This showed that the basic concept is sound, but that more support is needed. The next step should be to extend the language and add compiler support, which will enhance ease-of-use and allow numerous optimisations. This can be improved further by providing system-supported containers

Algorithms for Dynamic Software Cache Coherence

In this paper, we investigate a class of cache coherence strategies in which an abstraction for shared data at the program-level, referred to as Shared Regions (SR), is used to manage caches dynamically through software. The practical value of these strategies is measured by their performance relative to existing hardware coherence protocols, and the complexity of the SR programming interface. We present detailed quantitative results highlighting the performance of a wide array of SR coherence algorithms, including some novel algorithms introduced in this paper that use direct cache-to-cache data transfers via software to improve performance. These algorithms are studied using execution-driven simulation and compared to a representative hardware strategy for a suite of parallel applications. We study the issue of programming complexity by analyzing the process of inserting Shared Regions program annotations into these applications. The experimental results show that the best SR coheren..