Lazy home-based protocol: Combining homeless and home-based distributed shared memory protocols

This paper presents our novel protocol design and implementation of an all-software page-based DSM system. The protocol combines the advantages of homeless and home-based protocols. During lock synchronization, it uses a homeless diff-based memory update using the update coherence protocol. The diff-based update during lock synchronization can reduce the time in a critical section since it reduces page faults and costly data fetching inside the critical section. Other than the update in lock synchronization, it uses a home-based page-based memory update using the invalidation coherence protocol. The protocol is called "lazy home-based" since the home update is delayed until the next barrier time. The lazy home update has many advantages such as less interruption in home nodes as well as less data traffic and a smaller number of messages. We present an in-depth analysis of the effects of the protocol on DSM applications.