行內仿真：嵌入式系統上虛擬化的優化技術

Inline Emulation: An Optimization Technique for Virtualization on Embedded Systems

李沅臻(Yuan-Cheng Lee)

指導教授 ： 薛智文

國立臺灣大學/電機資訊學院/資訊工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.03141

摘要

以往受限於嵌入式處理器的計算能力，在嵌入式系統中採用虛擬化技術曾是個不切實際的想法。然而在現今的嵌入式系統中，虛擬化的需求卻日益增加。採用虛擬化技術可以完整地運用多核心的資源，也可增進與雲端計算的整合運作。然而，目前有關於嵌入式系統虛擬化的研究並不多，使用的技術也多半是基於過去 x86 平台發展而來。在這篇論文中，我們提出名為行內仿真的優化技術，以降低在嵌入式系統中採用虛擬化所產生的額外成本，並增進模擬權限指令的效能。同時，我們在 Android 仿真器中實作適用於 ARMv5 架構的行內仿真，以驗證其設計的正確性及適用性。在微觀層次的分析中，其結果指出行內仿真在模擬特定的指令時，最快可比一般半虛擬化技術快 7.1 倍。對於整個系統而言，實驗結果也證實行內仿真不但可以降低開發成本，同時也可以增加系統效能。

關鍵字

虛擬化 ； 行內仿真 ； 嵌入式系統 ； 優化 ； 敏感指令 ； Xen

並列摘要

For embedded systems, virtualization once seemed to be an impractical idea because of the limited capability of embedded processors and it is very challenging to design an efficient virtualization environment. In addition, the development cost is usually high for porting operating systems to adopt virtualization on embedded systems. However, the demand for virtualization on embedded systems is growing in these days. The main reasons of adopting virtualization include fully utilizing multi-core processors, cloud computing collaboration, and so on. Nevertheless, there are currently few researches about virtualization on embedded systems and most techniques are developed based on x86 platform. In this paper, we present a new optimization technique called inline emulation to lower overhead of adopting virtualization on embedded systems and increase the performance of emulating privileged instructions. We also implement inline emulation for ARMv5 architecture and evaluate the prototype in Android Emulator, which is an emulator of ARM platform. According to the experiment result, it suggests that inline emulation not only lowers the development cost but also increases system performance.

並列關鍵字

virtualization ； inline ； emulation ； embedded systems ； optimization ； sensitive instruction ； Xen

參考文獻

[9] Gerald J. Popek and Robert P. Goldberg. Formal requirements for virtualizable third generation architectures. Commun. ACM, 17(7):412–421, July 1974.

[10] Muli B. Yehuda, Michael D. Day, Zvi Dubitzky, Michael Factor, Nadav Har’El, Abel Gordon, Anthony Liguori, Orit Wasserman, and Ben A. Yassour. The turtles project: design and implementation of nested virtualization. In Proceedings of the 9th USENIX conference on Operating systems design and implementation, OSDI’10, pages 1–6, Berkeley, CA, USA, 2010. USENIX Association.

[16] Joo-Young Hwang, Sang-Bum Suh, Sung-Kwan Heo, Chan-Ju Park, Jae-Min Ryu, Seong-Yeol Park, and Chul-Ryun Kim. Xen on ARM: System Virtualization Using Xen Hypervisor for ARM-Based Secure Mobile

[1] Fabrice Bellard. QEMU, a fast and portable dynamic translator. In ATEC’05: Proceedings of the annual conference on USENIX Annual Technical Conference, page 41, Berkeley, CA, USA, 2005. USENIX Association.

[2] Splashtop Inc. Splashtop website, 2011. http://www.splashtop.com.