Research And Achieve About The Optimization Of Android Fast Boot Technique

With the advent of the mobile web era, the mobile terminals equipped with smart operating system have been become a crucial entrance of the Internet and innovation platform. Currently, the global mobile device market is experiencing explosive development. The smart operating system Android developed by Google has nearly 80% share of market worldwide, and it is undoubtedly the dominant system in this area. Due to its openness and versatility character, as well as free open source, Android is not only used in traditional areas,such as phones, tablets, smart TVs, but also will be applied to other fields such as industrial control, medical, transportation in the future. However, with the development of Android, it provides more and more functions and needs to adopt to increasing number of peripherals, it becoming increasingly complex. As a consequence, Android device takes a long time to boot, which is very negative to the user experience.Aiming at solve this problem, this thesis proposed a strategy, called fast-boot program based on Swsusp(software suspend), to accelerate the boot process of Android based on the analysis of Android boot process and Android power management. In the meantime, based on this program, an optimization program to improve the startup speed further was studied. The related theory such as Android system architecture, Android power management, and Android boot process was studied. After the process of bootloader and Linux kernel, Android system boot Android applications system, the load process of Android local service and classes is very time expensive, which contributes to the result that the load time of Android applications system occupies 80% time of the Android startup. According to the hibernation and resume strategys of Android power management mechanism, fast-boot technology means suspending the whole system, saving the system snapshot of some moment as an image stored to the external memory devicee. After booting Linux kernel in the next boot process, the system does not boot Android application, instead, it read system snapshot stored before to restore the system. This startup stratege skips the boot process of Android system and faster the whole startup process by 50%. Two major bottlenecks that impact the boot speed was obtained by analysising the above fast boot strategy. One is the image size, reading the image occupying 50% of the boot time. The size of image is around 170 M, and read speed is storage media related(15M/s for SD card). Thus, reducie the image size is a feasible way to improve boot speed. By analysising the Linux memory manages strategy, optimizing the memory allocation methods in the process of generating the image is reclaiming those memories which are non-critical for system. This optimization results a 40 M size of image, which will greatly reduce the time to read image as well as the system boot time. The other one is kernel boot, because many parts of the kernel boot is redundant to restore system. Optimizing the kernel boot process can reduce the kernel boot time. It only takes 10 s for system boot process after the proposed optimization method is applied which improves the system boot speed greatly.