The design of a scalable, hierarchical-bus, shared-memory multiprocessor

The hierarchical-bus architecture is an attractive solution to many of the problems associated with connecting processors together into a multiprocessing system but it also poses a number of design challenges. This thesis evaluates several architectural features of a hierarchical-bus multiprocessor. Our results show that applications with significant amounts of shared data achieve higher performance when run on a multiprocessor with a hierarchy of buses than on a single-bus multiprocessor. Also, applications with a significant number of write accesses to private data perform better using a cache protocol that modifies data within the cache (a copy-back protocol). This thesis describes a copy-back protocol for a hierarchical-bus multiprocessor and compares it with a cache protocol that broadcasts writes on the bus (a write-through protocol)