Reducing the Overhead of Migratory-Sharing Accesses for the Linked-Based Directory Coherence Protocols in Shared-Memory Multiprocessor systems

Abstract

Migratory-sharing objects are the data structures manipulated by only a single processor at any given time [1]. This type of accessed by the merge of the invalidation/update requests and the cache misses. P. Stenstrom et al. proposed a mechanism to optimize the migratory-sharing accesses for the central directory coherence protocols [2]. However, their mechanism can not support the linked-based directory protocols. Therefore, in this paper, we proposed a technique to reduce the overhead of migratory-sharing accesses for the linked-based directory protocols in some degree. Our mechanism can be implemented in various write policies, including the write-invalidate, write-update, and the write-competitive policies. Based on a program-driven simulation environment and a set of benchmarks, we have evaluated the performances for the various write policies. As a result, it can be shown that our method can effectively reduce the overhead of the migratory-sharing accesses.