Distributed shared memory for high performance networks

This paper describes the design and implementation of a distributed shared memory facility for high performance networks. Distributed Shared Memory (DSM) also known as a distributed global address space (DGAS) is a term in computer science that refers to a wide class of software and hardware implementations in which each node of a cluster has access to a large shared memory in addition to each node's limited non-shared private memory. DSM systems can be implemented within an operating system or as a programming library. DSM systems implemented in the operating system can be thought of as extensions of the underlying virtual memory architecture. Such systems are transparent to the developer which means that the underlying distributed memory is completely hidden from the users. This paper describes the design and implementation of a page based distributed shared memory facility for high performance networks which organizes the shared memory into pages of fixed size. The aspects of implementation of Distributed Shared Memory are (1) The consistency model used is sequential consistency model which is a light weight, distributed protocol, the strongest consistency that is practicable when there are communication delays over the network; (2) Provides the clean interface between the user-level server and the kernel; (3) The facility extends the FreeBSD VM system in a very non-intrusive way.