An energy-delay efficient 2-level data cache architecture for embedded system

Abstract

We propose a 2-level data cache architecture with a low energy-delay product tailored for the embedded systems. The L1 data cache is small and direct-mapped, and employs a write-through policy. In contrast, the L2 data cache is set-associative and adopts a write-back policy. Consequently, the L1 data cache is accessed fast and is able to provide high cache bandwidth while the L2 data cache is effective in reducing global miss rate. To reduce the penalty of high miss rates caused by the small L1 data cache, we propose an ECP (Early Cache hit Predictor) scheme. The ECP predicts if the L1 cache has the requested data using both partial address generation and L1 cache hit prediction. If so, the L2 data cache is directly accessed. To reduce high energy cost of accessing the L2 data cache due to heavy write-through traffic between the two cache levels, we propose a one-way write scheme. From our simulation-based experiments, the proposed 2-level data cache architecture shows average 3.6% and 50% improvements in overall system performance and energy consumption of the data cache and address generation, respectively.