Fast locks in distributed shared memory systems

Synchronization and remote memory access delays cause staggering inefficiency in most shared memory programs if run on thousands of processors. The authors introduce efficient lock synchronization using the combination of group write consistency, which guarantees write ordering within groups of processors, and eagersharing distributed memory, which sends newly written data values over fast network links whenever shared data are written locally. This fast locking method uses queue-based locks and a group root as a lock manager. Write ordering allows lock grants and releases to immediately follow final shared data writes. Most other consistency models need shared writes to be completed globally before lock release. Program execution times are much shorter using group write consistency than weak, release, or entry consistency.<>