Time predictability is difficult to achieve in the complex, layered execution environments that are common in modern embedded devices such as smartphones. We explore adopting the Android programming model for a range of embedded applications that extends beyond mobile devices, under the constraint that changes to widely used libraries should be minimized. The challenges we explore include the interplay between real-time activities and the rest of the system, how to express the timeliness requirements of components, and how well those requirements can be met on stock embedded platforms. We detail the design and implementation of our modifications to the Android framework along with a real-time VM and OS, and we provide experimental data validating feasibility over five applications.

Since the introduction of the smartphone, mobile computing has become pervasive in our society. Meanwhile, Mobile devices have evolved far beyond the stereotypical personal devices and been employed in various traditional real-time embedded domains. Of the currently available mobile systems, Android has seen the most widespread deployment outside of the consumer electronics market. Its open source nature has prompted its ubiquitous adoption in sensing, medical, robotics, and autopilot applications. However, it is not surprising that Android does not provide any real-time guarantee since it is designed as a mobile system and optimised for mobility, user experience, and energy efficiency. Although there has been much interest in adopting Android in real-time contexts, surprisingly little work has been done to examine the suitability of Android for real-time systems. Existing work only provides solutions to traditional problems, including real-time garbage collection at the virtual machine layer, real-time OS scheduling and resource management. While it is critical to address these issues, it is by no means sufficient. After all, Android is a vast system that is more than a Java virtual machine and a kernel.

Time predictability is difficult to achieve in the complex, layered execution environments that are common in modern embedded devices. We consider the possibility of adopting the Android programming model for a range of embedded applications that extends beyond mobile devices, under the constraint that changes to widely used libraries should be minimized. The challenges we explore include: the interplay between real-time activities and the rest of the system, how to express the timeliness requirements of components, and how well those requirements can be met on stock embedded platforms. We report on the design and implementation of an Android virtual machine with soft-real-time support, and provides experimental data validating feasibility over three case studies.

This paper presents our work on the inception of RTDroid, a variant of Android that provides predictability to Android applications. Although there has been much interest in adopting Android in real-time contexts, surprisingly little work has been done to examine the suitability of the Android franework layer for real-time systems. Existing work only provides solutions to traditional problems, including adding support for real-time garbage collection at the virtual machine layer as well as kernel-level real-time scheduling and resource management. While it is critical to address these issues, it is by no means sufficient. After all, Android is a vast system that is more than a Java virtual machine and a kernel. Thus, this paper goes beyond existing work and examines the internals of Android, the Android programming model, libraries, and core systems services. We discuss the implications and challenges of adapting Android constructs and core system services for real-time and present a solution for each. Our system is unique in that it redesigns Androids internal components, replaces Androids Dalvik VM with a real-time VM, and leverages off-the-shelf real-time OSes. We demonstrate the feasibility and predictability of our solution on three different platforms. The evaluation results show that our design can successfully provide predictability to Android applications even under heavy loads.

This paper presents RTDroid, a variant of Android that provides predictability to Android applications. Although there has been much interest in adopting Android in real-time contexts, surprisingly little work has been done to examine the suitability of Android for real-time systems. Existing work only provides solutions to traditional problems, including real-time garbage collection at the virtual machine layer and kernel-level real-time scheduling and resource management. While it is critical to address these issues, it is by no means sufficient. After all, Android is a vast system that is more than a Java virtual machine and a kernel.