An efficient hybrid cache coherence protocol for shared memory multiprocessors

This paper presents a new tree-based cache coherence protocol which is a hybrid of the limited directory and the linked list schemes. By utilizing a limited number of pointers in the directory, the proposed protocol connects the nodes caching a shared block in a tree fashion. In addition to the low communication overhead, the proposed scheme also contains the advantages of the existing bit-map and tree-based linked list protocols, namely, scalable memory requirement and logarithmic invalidation latency. We evaluate the performance of our protocol by running four applications on an execution-driven simulator. Our simulation results show that the performance of the proposed protocol is very close to that of the full-map directory protocol.