In a hierarchically structured ring-based COMA(Cache Only Memory Architecture) system, processing nodes generate a large amount of traffic in order to maintain cache consistency. It is known that such communication traffic is a major factor that cause the bottleneck in a high level interconnection network, restricting the scalability and performance of the system. In this thesis, we propose a new cache coherence protocol that minimizes the communication traffic generated for maintaining cache coherence. This protocol restricts the propagation of network traffic by differentiating cache states among locally shared and globally shared. The performance gain is measured by execution-driven simulation and the results show that the network traffic is reduced by average 12%.
