A hierarchical memory directory scheme via extending SCI for large-scale multiprocessors

SCI (scalable coherent interface) is a pointer-based coherent directory scheme for large-scale multiprocessors. Large message latency is one of the problems with SCI because of its linked list structure: the searching latency can grow as a linear order of the number of processors. The authors focus on a hierarchical architecture to propose a new scheme-EST (extending SCI-tree), which may reduce the message traffic and also take advantage of the topology property. Simulation results show that the EST scheme is effective in reducing message latency and communication cost when compared with other schemes.