A DVFS-aware cache bypassing technique for multiple clock domain mobile SoCs

Multiple clock domains mobile SoCs typically adopt dynamic voltage and frequency scaling (DVFS) for flexible power/energy management. However, adoption of system-level cache under DVFS-enabled CPU may incur abnormal cache hierarchy (i.e., a delay reversal between the high-level and low-level caches). It may lead to performance- and energy-inefficiency due to slower data delivery and meaningless accesses to intermediate levels of caches. To resolve this problem, we propose a DVFS-aware cache bypassing technique. Our technique profiles latencies of the various levels of the caches. Based on the profiled information, our technique adaptively bypasses intermediate levels of caches in the case of abnormal cache hierarchy and applies power-gating to that cache memory for better energy efficiency. According to our evaluation, our technique reduces L2 and system-level cache energy consumption by up to 14.5% while improving performance by up to 0.13% compared to the baseline.