标题：DS-Cache: A Refined Directory Entry Lookup Cache with Prefix-Awareness for Mobile Devices
作者：Han, Lei ;Xiao, Bin ;Dong, Xuwei ;Shen, Zhaoyan ;Shao, Zili
作者机构：[Han, Lei ;Xiao, Bin ] Department of Computing, Hong Kong Polytechnic University, Hong Kong;[Shen, Zhaoyan ] School of Computer Science and Technology 更多
会议名称：22nd Design, Automation and Test in Europe Conference and Exhibition, DATE 2019
会议日期：March 25, 2019 - March 29, 2019
来源：Proceedings of the 2019 Design, Automation and Test in Europe Conference and Exhibition, DATE 2019
摘要：Our modern devices are filled with files, directories upon directories. Applications generate huge I/O activities in mobile devices. Directory cache is adopted to accelerate file lookup operations in the virtual file system. However, the original directory cache recursively walks all the components of a path for each lookup, leading to inefficient lookup performance and lower cache hit ratio. In this paper, we for the first time fully investigate the characteristics of the directory entry lookup in mobile devices. Based on our findings, we further propose a new directory cache scheme, called Dynamic Skipping Cache, which adopts an ASCII-based hash table to simplify the path lookup complexity by skipping the common prefixes of paths. We also design a novel lookup scheme to optimize the directory cache hit ratio. We have implemented and deployed DS-Cache on a Google Nexus 6P smartphone. Experimental results show that we can significantly reduce the latency of invoking system calls by up to 57.4%, and further reduce the completion time of real-world mobile applications by up to 64%.
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