A Buffer Cache Algorithm for Hybrid Memory Architecture in Mobile Devices

In general computing environments including mobile devices, buffer cache algorithm is generally used to mitigate the performance gap between CPU and secondary storage. However, traditional DRAM-based buffer cache architecture reveals a power consumption problem in mobile devices, because it periodically performs the refresh operations to maintain data in DRAM. In addition, traditional buffer cache algorithms never consider the states of mobile applications (e.g., foreground and background state). In this paper, we propose a novel buffer cache algorithm, which efficiently addresses the above issues based on hybrid main memory architecture that is comprised of DRAM and PCM. Our algorithm is motivated by key observation that background applications on mobile device rarely issue I/O requests as well as they can degrade the performance of foreground applications because of the interferences among the I/O requests of applications. For evaluation, we implemented our algorithm and compared its performance against two other algorithms. Our experimental results show that our algorithm reduces the elapsed time of the foreground applications by 53 % on average and the power consumption by 23 % on average without any negative performance effects on background applications.