Proving Correctness of a Distributed Shared Memory Implementation

DiSOM [3, 4, 2] is a distributed shared memory system that o ers users an atomic collection of memory cells provided they satisfy certain well-formedness conditions. This report proves the correctness of DiSOM. The system partitions memory into a set of objects and implicitly associates a read-write lock with each object. Users synchronize accesses to these objects explicitly executing synchronization operations on the associated locks. DiSOM's distributed read-write lock implementation guarantees progress and the usual read-write lock exclusion conditions. DiSOM guarantees an atomic view of memory provided: (1) all write accesses to an object's cells occur when the object's lock is acquired for writing; and (2) read accesses occur only when the lock is acquired for reading or writing. This model is similar to entry consistency [1] but it is simpler and provides an atomic memory instead of a sequentially consistent one.