Comparison of Hybrid and Hierarchical Swap Architectures in Android by using NVM

Abstract

As the application ranges supported by smartphones grow rapidly, the necessity of virtual memory swapping is becoming increasingly important. However, current Android platforms do not support swapping because flash memory does not provide consistent performance for swapping. In this paper, we present a novel swap architecture that adds a small size of NVM to efficiently hide the slow swap problem of Android. Specifically, we present an efficient hybrid swap scheme, which prevents the pollution of NVM from a large portion of single-access data that we observe in Android swapping traces. Experimental results show that our scheme reduces the number of flash I/Os by 6.2% on average and up to 24% by identifying cold data and prohibiting them from entering NVM. We also show the effectiveness of the proposed scheme under various swap architectures.