在即時系統上，動態電壓調變演算法是目前最有效率且最重要的降低處理器耗能的方法。目前有許許多多的學術單位，都投入動態電壓調變演算法的研究工作，討論如何在不同的系統組態與模型上，執行動態變壓調變演算法，使得到最低的耗能。在此篇論文中，我們將提出一個全面且完整的比較，探討現今幾個最重要的低耗能靜態優先權分配即時系統排程兼動態電壓調變演算法。
我們的分析將著重在各演算法於系統的耗能效率。我們的論文將是提供給設計低耗能即時系統研究的參考標準。除了理論上的分析，我們還從兩個角度上，做了各演算法的模擬實驗，客觀的比較其耗能效率。最後，經由這些測試與比較，我們可以明確的知道，每個演算法最適合用在哪一種系統，做為低耗能靜態優先權分配即時系統排程兼動態變壓調變演算法的評介。

Dynamic voltage scaling (DVS) has become the most efficient and im-portant technique for reducing energy consumption of processors, es-pecially in embedded hard real-time systems. A number of approaches have been proposed by different research groups to utilize DVS on different task models and system configurations. In this paper, we provide a comprehensive comparison of DVS-capable low-power real-time scheduling algorithms for a periodic fixed-priority task model. Our analysis focuses on their energy efficiency and performance com-parison. This paper intends to serve as a reference guild in the design of a low-power real-time system. In addition to qualitative analysis, we also conducted experiments to quantitatively compare the perfor-mance of these algorithms on two practical scenarios. Finally, we give the definition of a task set suitable for each algorithm.

[1] H. Aydin, R. Melhem, D. Moss´e, and P. M.-Alvarez. Dynamic and aggressive scheduling techniques for power-aware real-time systems. In Proceedings of the 22nd IEEE Real-Time Systems Symposium, pages 95–105, 2001.
[2] H. Aydin, R. Melhem, D. Mosse, and P. M.-Alvarez. Power-aware scheduling for periodic real-time tasks. IEEE Transactions on Computers, VOL. 53(5):p584– 600, May 2004.
[3] C. Im, S. Ha, and H. Kim. Dynamic voltage scheduling with buffers in low-power multimedia applications. ACM Transations on Embedded Computing Systems, 3(4):686–705, 2004.
[4] R. Jejurikar and R. Gupta. Procrastination scheduling in fixed priority real-time systems. In Language, Compiler and Tool Support for Embedded Systems, 2004.
[5] R. Jejurikar, C. Pereira, and R. Gupta. Leakage aware dynamic voltage scaling for real time embedded systems. In 41th Design Automation Conference, 2004.
[6] N. Kim, M. Ryu, S. Hong, M. Saksena, C.-H. Choi, and H. Shin. Visual assessment of a real-time system design: a case study on a cnc controller. In Proceedings of the 17th IEEE Real-Time Systems Symposium, 1996.
[7] W. Kim, J. Kim, and S. L. Min. A dynamic voltage scaling algorithm for dynamic-priority hard real-time systems using slack time analysis. In Pro-ceedings of the Conference on Design, Automation and Test in Europe, pages 788–794, 2002.
[8] W. Kim, J. Kim, and S. L. Min. Dynamic voltage scaling algorithm for fixed-priority real-time systems using work-demand analysis. In Proceedings of the 2003 International Symposium on Low Power Electronics and Design, pages 396–401. ACM Press, 2003.
[9] W. Kim, D. Shin, H.-S. Yun, J. K., and S. L. Min. Performance comparison of dynamic voltage scaling algorithms for hard real-time systems. In Proceed-ings of the 8th IEEE Real-Time and Embedded Technology and Applications Symposium, page 219. IEEE Computer Society, 2002.
[10] C.-H. Lee and K. G. Shin. On-line dynamic voltage scaling for hard real-time systems using the edf algorithm. In Proceedings of the 25th IEEE Real-Time Systems Symposium, December 2004.
[11] C. L. Liu and J. Layland. Scheduling algorithms for multiprogramming in a hard real-time environment. Journal of the ACM, 10(1):46–61, 1973.
[12] C. D. Locke, D. R. Vogel, and T. J. Mesler. Building a predictable avionics platform in ada: a case study. In Proceedings of the 12th IEEE Real-Time Systems Symposium, 1991.
[13] B. Mochocki, X. Sharon Hu, and G. Quan. Practical on-line dvs scheduling for fixed-priority real-time systems. In The 11th IEEE Real-Time and Embedded Technology and Applications Symposium, 2005.
[14] P. Pillai and K. G. Shin. Real-time dynamic voltage scaling for low-power embedded operating systems. In 18th ACM Symposium on Operating Systems Principles, 2001.
[15] G. Quan and X. S. Hu. Energy efficient fixed-priority scheduling for real-time systems on variable voltage processors. In Annual ACM IEEE Design Automation Conference, pages 828–833, 2001.
[16] G. Quan and X. S. Hu. Minimum energy fixed-priority scheduling for variable voltage processors, 2003.
[17] G. Quan, L. Niu, X. S. Hu, and B. Mochocki. Fixed priority scheduling for reducing overall energy on variable voltage procassors. In Proceedings of the 25th IEEE Real-Time Systems Symposium, 2004.
[18] S. Saewong and R. Rajkumar. Practical voltage-scaling for fixed-priority rt-systems. In The 9th IEEE Real-Time and Embedded Technology and Applica-tions Symposium, page 106, 2003.
[19] Y. Shin and K. Choi. Power conscious fixed priority scheduling for hard real-time systems. In Annual ACM IEEE Design Automation Conference, pages 134–139, 1999.
[20] Y. Shin, K. Choi, and T. Sakurai. Power optimization of real-time embedded systems on variable speed processors. In International Conference on Computer
Aided Design, pages 365–368. IEEE Press, 2000.
[21] F. Yao, A. Demers, and S. Shenker. A scheduling model for reduced cpu energy. In IEEE Annual Foundations of Computer Science, pages 374–382, 1995.
[22] H.-S. Yun and J. Kim. On energy-optimal voltage scheduling for fixed-priority hard real-time systems. ACM Transactions on Embedded Computing Systems, 2:393–430, 2003.