No abstract

Mobile devices have become the most important devices in our life. However, they are limited in battery capacity. Therefore, low-power computing is crucial for their long lifetime. A spin-transfer torque RAM (STT-RAM) has become emerging memory technology because of its low leakage power consumption. We herein propose MH cache, a multi-retention STT-RAM-based cache management scheme for last-level caches (LLC) to reduce their power consumption for mobile hardware rendering systems. We analyzed the memory access patterns of processes and observed how rendering methods affect process behaviors. We propose a cache management scheme that measures write-intensity of each process dynamically and exploits it to manage a power-efficient multi-retention STT-RAM-based cache. Our proposed scheme uses variable threshold for a process’ write-intensity to determine cache line placement. We explain how to deal with the following issue to implement our proposed scheme. Our experimental results show that our techniques significantly reduce the LLC power consumption by 32% and 32.2% in single- and quad-core systems, respectively, compared to a full STT-RAM LLC.

No abstract

Conventional 2-level cache architecture is not efficient in mobile systems when small programs that do not require the large L2 cache run. Bypassing the L2 cache for those small programs has two benefits. When only a single program runs, bypassing the L2 cache allows to power it down removing its leakage energy consumption. When multiple programs run simultaneously on multiple cores, small programs bypass the L2 cache while large programs use it. This decreases conflicts in the L2 cache among those programs increasing overall performance. From our experiments using cycle-accurate performance and energy simulators, our proposed L2 cache architecture supporting bypassing is shown to be effective in reducing L2 cache energy consumption and increasing overall performance of programs.