An innovative implementation for directory-based cache coherence in shared memory multiprocessors

Abstract

Directory-based cache coherence protocol is accepted as the common technique in large scale shared memory multiprocessors because of its scalability. Although it was extensively studied in the past, however, the memory overhead and long miss penalty entailed by this protocol are the major obstacles to scale for large scale multiprocessors. On the other hand, the ever-increasing cache line size makes the false sharing problem more serious than before, which will lead to high miss rate. Based on the scope consistency, we propose a lock-specific home-based cache coherence protocol. In this new cache coherence protocol, all directory memory overhead are eleminated completely and false sharing problem and high miss rate will be sloved greatly at the cost of small write notice buffer in each processor.