Linked list cache coherence for scalable shared memory multiprocessors

This paper presents a singly-linked distributed directory (SDD) cache coherence protocol and compares the performance of the SDD protocol with the fully mapped centralized directory protocol and the IEEE SCI Standard protocol. To maintain coherence, the SDD protocol uses a linked list of cache lines that contain shared copies of the data. The protocol has scalable cost. Coherency related messages are not required to be delivered in order, thus allowing adaptive routing, making the performance more robust in the presence of congested networks. The authors analysis shows that the SDD protocol has generally better performance in the presence of memory and interconnect contention. They discuss the various factors, such as memory reference behavior and interconnect traffic, that affect the performance of these protocols