Design of hierarchical cache coherence protocol based on Chiplet architecture

This paper proposes a directory-based hierarchical cache coherence protocol for highly scalable Chiplet architectures. The proposed protocol can be seamlessly divided into two independent levels, the first level handling the inter-core cache coherency within a single Die while the second level dealing with the intra-Die cache coherency across multiple Dies. The proposed protocol is implemented using a two-level directory structure which exhibits superior scalability in terms of storage overhead. Simulation results indicate our approach using a two-level directory structure reduces the miss rate of the shared last-level cache (LLC) as compared to conventional approach using a single-level directory structure. This reduction enhances overall cache performance as the average memory access latency is reduced.