An improvement technique for hybrid protocol for software distributed shared memory

Recently, many different protocols have been proposed for software Distributed Shared Memory (DSM) that provides a shared-memory programming model on distributed memory hardware. This paper identifies two problems that deteriorate the performance of a hybrid protocol, an adaptive invalidate/update protocol, and then proposes an improved hybrid protocol to solve these problems. At the point of synchronization, the proposed protocol applies an update protocol not only to the processors previously accessing the page, as in the existing protocol, but also to all processors if the number of processors previously accessing the page is more than a given parameter value. The proposed protocol was implemented in CVM, a software DSM system, and evaluated on eight Sun-ultra 1 workstations.