Analysis And Improvement Of Storage IO Performance In Linux Mobile Terminal

Linux operating system, with its open source, high portability, low cost of software licensing, and flexible customization, has been widely used in mobile device market. With respect to a general purpose computer, the mobile terminal brings new challenges to the operate system, especially in volume and mobility. Flash has become a standard configuration in mobile terminal because of its small size, simple structure and low energy consumption. Therefore, improving IO performance of flash storage is of great significance for mobile terminals.In order to optimize storage IO performance of linux in mobile terminals, this paper makes a detailed study of some related technologies in Linux file system IO framework, including: page caching mechanism, file read-ahead mechanism, scheduling algorithms, IO Qos and etc. An optimization scheme for storage IO performance is put forward. Specifically, The main results obtained in this paper are outlined as follows:1. The working principle and kernel implementation of VFS layer, general block layer and device driver layer in the IO framework of Linux kernel file system have been analyzed. The Cgroup framework of the Linux kernel which is used for resource management, blkio subsystem in Cgroup which is specifically for IO Qos control and the implementation of IO Qos in CFQ algorithms are also studied.2. The open-source file systems of linux which are widely used for flash devices, including EXT4, F2 FS and BTRFS, are studied. the general parameters and file system specific parameters in Linux kernel that affecting the file system IO performance have been explained in detail. The method to optimize the file system IO performance by adjusting parameters under different scenarios has been proposed.3. The realization of Linux kernel page cache and file read-ahead mechanism have been studied. IO performance of Linux storage devices is optimized by adjusting the file read-ahead kernel parameters in different application scenarios.4. The basic idea and implementation details of CFQ, NOOP and DEADLINE scheduling algorithms in linux kernel, and kernel parameters related to various scheduling algorithms have been studied. The method to optimize the IO performance of mobile terminal storage device by adjusting scheduling algorithm and parameters in different scenarios has been proposed.5. The read and write characteristics of flash storage devices have been studied. the method of how to create an eraser block aligned file system based on physical characteristics of flash devices has been proposed, which can greatly enhance the write performance and is helpful for the life of flash devices.6. The optimization scheme has been tested and verified on and Pandaboard ES platform with Linux V3.8 kernel. SD card is used as storage medium. The proposed schemes are tested in different IO scenarios simulated by FIO and practical applications. The results are given and analyzed in depth.