Exploiting Early Tag Access for Reducing L1 Data Cache Energy in Embedded Processors

In this paper, we propose a new cache design technique, referred to as early tag access (ETA) cache, to improve the energy efficiency of data caches in embedded processors. The proposed technique performs ETAs to determine the destination ways of memory instructions before the actual cache accesses. It, thus, enables only the destination way to be accessed if a hit occurs during the ETA. The proposed ETA cache can be configured under two operation modes to exploit the tradeoffs between energy efficiency and performance. It is shown that our technique is very effective in reducing the number of ways accessed during cache accesses. This enables significant energy reduction with negligible performance overheads. Simulation results demonstrate that the proposed ETA cache achieves over 52.8% energy reduction on average in the L1 data cache and translation lookaside buffer. Compared with the existing cache design techniques, the ETA cache is more effective in energy reduction while maintaining better performance.