Improving the Boot Time of the Android OS

Increasing application requirements in embedded systems demand additional software initialization and configuration during startup, which adversely affects system boot time. The demand for fast startup is motivated by embedded systems, not only for consumer electronics such as digital TV and mobile phones but also for devices in automotive, medical and other applications. This paper presents novel approaches to reduce the startup time of complex embedded systems, using Android OS as an example. The startup latency of Android is analyzed in order to find ways to reduce the boot time. Then to reduce startup time, we propose a better U-boot Fast-Boot based on Suspend-Resume techniques, improve the read speed of SD cards, and try to reduce the size of suspend images. Our measurements show that these methods can reduce the total startup time by 83%. Index Terms — Android, boot time, fast-boot, U-boot, suspend-resume Advances in computing technology, enhanced communication bandwidth, and innovative software have brought increased functionality and capabilities to consumer electronics. Television sets now have embedded microprocessors and operating systems that allow internet access, streaming media and a wide variety of multimedia applications. Tablet PCs and smart phones come loaded with a wide variety of apps. Unfortunately, the addition of new features; support for multiple services and data formats; complex and sometimes proprietary multimedia libraries; and increased hardware complexity has driven an increase in the complexity of the software that controls these embedded systems. In the early days of TV, we had to wait for vacuum tubes to warm up, before we could use the TV, but advances in electronics brought us to the day where devices could be turned on almost instantly, and you could readily switch between channels and quickly view the screen. As we moved to digital television, and especially smart televisions, consumers lost that access speed. One of the delays seen by consumers is the delay in starting the device from an off state. The demand for fast startup is mostly motivated by embedded systems, because it is one of the most important factors affecting the decisions of buyers. A long waiting time will alienate users, especially, the users of consumer devices such as digital TV. We address that delay in this paper, and suggest ways that system designers can improve device start time. Size, power and price constraints of embedded systems make software design and implementation uniquely difficult for engineers. Traditionally, the demand for embedded software was met by only a few proprietary platforms. In 2008, an open source software platform primarily for smart mobile phones, Android, was launched by the Open Handset alliance led by Google . Android has found great success since it entered the mobile terminal market. It is a complete embedded software stack, comprising of a modified Linux-based kernel, middleware, application framework and applications. As an open platform with free and convenient tools offered to application developers, Android Operating System is now also being used in digital TVs and tablet pcs and other devices. Android’s complicated software stack architecture can yield great returns for hardware and supply rich software services. However, in order to support converging applications, Android comes packed with features, resulting in considerably large code size. These advantages also delay the boot-up time of android devices up to an average of 30 seconds, therefore it is a great platform for our research. This paper reports the results of our investigations into improving the boot time of Android devices. Based on our measurements and analysis of the Android boot procedure, we found that the most of time during the boot process is spent on the Android service and application. Using these results, we developed a new approach for booting which improves the startup time. This approach is based on the Suspend-Resume technique, but it is very different from that. When a user powers off a device it first suspends a running system and makes a system image including copies of CPU registers, memory and device state that is then stored on disk or Flash memory, after that the system will shut down all power to the device, not just enter a sleep mode. When the user powers on the device, it reloads the stored image from external disk and resumes the system with the suspended image instead of cycling through a full boot procedure. This technique is very useful for non-battery-powered devices and frequently rebooted devices such as Digital TV. It also can save battery for battery-powered devices like mobile phones and Improving the Boot Time of the Android OS Digital Object Indentifier 10.1109/MC.2013.264 0018-9162/$26.0