SwapBench: The Easy Way to Demystify Swapping in Mobile Systems

Mobile systems such as smartphones and tablets are re-adopting swapping -- a mature but by rarely used OS feature -- to extend memory capacity without adding more DRAM, especially low-end devices. This resurgence of swapping in mobile systems has inspired both traditional "off-the-rack" schemes and new approaches based on compression and new hardware. Their vastly different designs, however, make them difficult for system designers to measure, compare and revise. In this paper, we propose an evaluation framework, SwapBench, to appraise swap schemes and focus on two important but overlooked metrics: application launch and switch. Cross-validation with microbenchmarks shows that SwapBench is accurate. Based on the findings from SwapBench, we further discuss the impacts of different approaches to swapping in mobile systems.