基于闪存特性的EXT4文件系统读写性能优化研究

Research on Performance Optimiazation of EXT4 File System Based on Flash Memory

摘要:

Android智能手机普遍采用闪存作为本地存储介质，这导致使用的EXT4文件系统存在读写性能损耗问题，间接影响了应用程序的使用体验，在分析性能损耗原因的基础上，提出一种针对EXT4文件系统日志功能优化方法。首先对EXT4文件系统日志功能进行研究，分析其如何维护日志数据，对比传统磁盘及闪存的不同特性提出性能损耗问题产生的原因，并给出解决方法，优化EXT4日志数据存取流程，以EXT4事务状态作为依据主动删除无用的日志数据，在不破坏原有日志功能的基础上，减少闪存设备垃圾回收过程中不必要的数据拷贝。通过对比实验证明，该方法能够提升Android手机中Ext4文件系统约11.8%的读写性能。

关键词:EXT4;日志;闪存设备;垃圾回收;Android系统

Abstract:

Android mobile phones generally use flash as a local storage medium, which leads to the use of EXT4 file system has the problem of loss of read and write performance, indirectly affecting the application experience. Based on the analysis of the causes of performance loss, this paper presents a method for optimizing the log function of EXT4 file system. First of all, EXT4 file system log function research, analysis of how to maintain journal data. By comparing the different characteristics of traditional disk and flash memory, we put forward the reasons for the performance loss problem and give the solution. This method takes EXT4 transaction status as a basis to actively delete useless log data, and reduces unnecessary data copy in flash device garbage collection process without destroying the original journal function. Through the comparative experiments show that this method can improve about 11.8% read and write performance of Ext4 file system in Android mobile phone.

Key words:EXT4;Journal;Flash Memory;Garbage Collection;Android System