a consistency architecture for hierarchical shared caches
Hierarchical Cache Consistency (HCC) is a scalable cache-consistency architecture for chip multiprocessors in which caches are shared hierarchically. HCC's cache-consistency protocol is embedded in the message-routing network that interconnects the caches, providing a distributed and scalable alternative to bus-based and directory-based consistency mechanisms. The HCC consistency protocol is "progressive" in that every message makes monotonic progress without timeouts, retries, negative acknowledgments, or retreating in any way. The latency is at most proportional to the diameter of the network. For HCC with a binary fat-tree network, the protocol requires at most 13 bits of additional state per cache line, no matter how large the system. We prove that the HCC protocol is deadlock free and provides sequential consistency.
shared caches cache consistency fat-tree deadlock sequential consistency memory hierarchy mapping collision progressive protocol message race