Thread ID based power reduction mechanism for multi-thread shared set-associative caches

In this paper, we propose a brand-new cache power reduction mechanism, Thread ID Cache (TID Cache), aiming to reduce dynamic power consumption of set-associative caches shared by multiple threads. TID tables are implemented at different levels of cache hierarchy to record thread IDs. When a thread accesses a cache way, the thread ID is updated to the corresponding entry in TID table. When the same thread accesses cache again, irrelevant ways owned by other threads can be avoided being accessed through comparing thread IDs in TID table. Experiments are conducted on TID Cache with the configuration of a 32KB 8-way L1 cache and a 128KB 8-way L2 cache. The results reveal that, when caches are shared by 16 threads, the proposed TID cache achieves 34% dynamic power reduction of L1 and 36% of L2 under the CloudSuite benchmarks, and the corresponding results are 42% of L1 and 48% of L2 under the SPLASH-2 benchmarks. Accordingly, the same proportion of dynamic power can be saved at the price of less than 0.8% area overhead of cache data arrays.