Xunify -- A Performance Debugger for a Distributed Shared Memory System

Distributed shared memory (DSM) offers advantages over message passing systems by allowing programmers to use a shared memory programming model. However, distributed shared memory systems present new challenges to performance evaluation and debugging. While programmers write programs using a shared memory model, the processes in the distributed system share information via messages. This abstraction can make it difficult to identify the sources of performance problems. We have developed an instrumentation system and performance evaluation tool called Xunify for monitoring and performance debugging of a DSM system. Xunify provides information in terms of the DSM program level, logical message level, and the transport protocol level