A Migrating-Home Protocol for Implementing Scope Consistency Model on a Cluster of Workstations

The performance of a software Distributed Shared Memory relies on an efficient memory consistency model, and a suitable protocol for implementing the model. This paper studies a new concept of a migrating-home protocol for implementing the scope consistency model. In this protocol, the home, which is the location of the most up-to-date copy of each memory page, can change among processors. We implement this idea on a cluster of UltraSPARC I model 140 workstations with ATM network. The migrating-home protocol outperforms the home-based approach and adapts better to the memory access patterns for most applications. It reduces communication overheads in forwarding page updates among the processors. Page faults can also be handled in a more efficient way. These factors reduce a considerable amount of data communicating within the cluster.