Virtualization has been a well-studied topic for traditional servers. As the demand for the support of virtualization on mobile devices emerged, it again became a popular research topic. However, most research work focused on the applications of mobile virtualization. Detailed knowledge of the characteristics of mobile devices is still lacking. In this paper, we focus on the memory management of mobile virtualization, and propose an optimized page translation oPT with hardware/software co-design. The usage pattern of mobile devices is also considered in the design so it is optimal in terms of the hit ratio of the second stage. The variability of translation time in the second stage is eliminated to provide nearly the same behavior as the non-virtualized architecture. We verify the correctness and feasibility of oPT with a formal proof and a comprehensive evaluation based on both software emulation and hardware implementation. The results indicate oPT can outperform the most popular method. The number of memory accesses is reduced by 51.38 to 56.01 percent, and the average translation time is reduced by 78.63 percent. In addition, the power consumption of the hardware unit in oPT is only about one third that of the traditional method.

Recently, the significant progress in embedded microprocessors made it practical to support virtualization on mobile devices. Unfortunately, memory management has not been well studied in consideration of the characteristics of mobile virtualization due to the challenging aspects on both hardware and software. With a formal proof on a novel design of page translation at the second stage, we propose a novel design of page translation on both hardware and software with higher translation speed, lower variance of latency, and lower hardware complexity. The experimental results suggest it can reduce memory access by 51.37% to 56.01% as compared with the traditional approach.

Virtualization has been widely adopted on servers for various purposes such as server consolidation, cloud computing, and so on. Recent years, the trend spreads on embedded systems, although it once seemed to be an impractical idea because of the limited capability of embedded processors. To further lower the overhead of adopting virtualization on embedded systems, we design an optimization technique, called inline emulation, to reduce the cost spending on paravirtualizing operating systems. Inline emulation can also be used in various virtualization environments to increase the performance of emulating privileged instructions. We implement inline emulation for ARMv5 architecture and evaluate in Android Emulator. The result shows it runs much faster, up to 7.4 times, than the common Para virtualization technique for cache-related operations and suggests that it not only lowers the development cost but also increases system responsiveness.