TEACA: Thread ProgrEss Aware Coherence Adaption for hybrid coherence protocols

Abstract

Hybrid coherence protocols can provide the scalability of directory protocols and low latency sharing miss handling in snooping protocols simultaneously. Unfortunately, how to adapt the hybrid protocols at runtime is not well studied. This paper proposes Thread ProgrEss Aware Coherence Adaption (TEACA) which utilizes the thread progress information as the hints to adapt hybrid coherence protocols. Specifically, TEACA fuses the memory system statistics to estimate the progress of threads. Based on the estimated thread progress information, TEACA dynamically categorizes threads into leader threads and laggard threads. The thread categorization decisions are then leveraged for efficient coherence adaption in hybrid coherence protocols. A case study on a recently proposed hybrid protocol (PATCH [29]) shows that, with the hints from TEACA, the enhanced hybrid protocol outperforms its baseline in both application execution time and energy dissipation.