Distributed Shared Memory (DSM) systems have been proposed to combine the programmability of traditional shared memory and the scalability of message-passing systems. Eager DSM systems can greatly reduce access latencies for remote data by keeping copies of shared values in local memory and updating them immediately whenever a shared datum changes. However, sharing all changes globally can limit the system performance. It is usually possible to transform a program into an equivalent form that generates much less traffic, and therefore executes much more efficiently. This paper describes a compile-time analysis model for transforming simple shared memory programs with parallelized loop structures into programs that are optimized for efficient execution on eager DSM systems.>

Introduces optimistic lock synchronization using the group write consistency (GWC) model. GWC guarantees strict ordering of all shared writes in a processor group. In optimistic synchronization, if a lock-requesting processor can assume that the lock is free, execution of mutually exclusive code starts immediately. A wrong assumption results in rollback. Shared variable updates remain in the group until the lock manager grants the lock to the requesting processor. By evaluating the time needed for three processors to execute mutually exclusive code, GWC can out-perform weak, release, and even entry consistency. Simulations of task management using exclusive access to a shared queue, also show much faster mutual exclusion with GWC. Optimistic mutual exclusion may further halve total delays in accessing shared resources.>