Efficient implementation of mutual exclusion locks in large multiprocessors

To ensure proper mutual exclusion, a lock is often employed to determine the processor among those which compete for the critical section. Accesses to such a mutual exclusion lock may create heavy synchronization traffic and/or serious contention over the network, thereby degrading system performance considerably. In this paper, we introduce an efficient lock scheme which keeps synchronization traffic low and avoids serious hot-spot contention. This is made possible by constructing a ring of the processors waiting for the critical section and by dispersing accesses to the lock. Our simulation results demonstrate that the proposed scheme indeed achieves better performance than prior techniques, promising good scalability