Directory Cache Coherence Scheme using the Number-Balanced Binary Tree

The directory-based cache coherence scheme is an attractive approach to solve the caceh coherence problem in a large-scale shared-memory multiprocessor.However, the exsting directory-based schemes have some problens such as the enormous storage overhead for a directory, the long invalidation latency, the heavy network condes-tion, and the low scalability.For resolving these problems, we propose a new directroy- based caceh coherence scheme which is suitable for building scalable, shred-memory multiprocessors.In this scheme, each directory en-try ofr a given memory block is a number-balanced binaty tree(NBBT) stucture.The NBBT has several proper-ties to effciently maintain the directory for the cache consistency such that the shape is unique, the maximum depth is [logn], and the tree has the minimum number of leaf nodes among the binarry tree with n nodes.Therefore, this scheme can reduce the storage overhead, the network traffic, and the inbalidation latency and can ensutr the high- scalability the large-scale shared-memory multiprocessors.