針對多核心Android系統之低耗能排程機制設計

隨著可攜式設備的功能日趨繁複，系統效能的需求漸趨提高，使用多核心處理器架構的可攜式裝置亦日漸增加。由於可攜式設備多以電池供電，在電池容量受限的狀況下，多核心系統的能源管理機制將成為影響設備操作時間的主要因素。目前主要的嵌入式系統電源管理如Linux電源管理、Android週邊管理等機制，多以自動管理週邊與處理器工作頻率，無法因應使用者的期待與需求，配合實際工作負載，節省系統能源，且無法動態開啟或關閉處理器核心，以符合實際使用需求。有鑑於此，本研究提出新式BPM-DFS(Bounded-Power Multi-core Dynamic Frequency Scaling)電源管理機制。此機制整合了一精確的系統組態選擇演算法、工作重新排程機制、與耗能預估模型，針對多核心的電腦系統，依使用者指定之電源預算(Power Budget)，藉由核心開啟與否、核心工作頻率調整、與工作的重新配置，在不高於電源預算下，儘可能提高工作速度。本研究並將BPM-DFS電源管理機制實現於四核心x86 Android系統，並與其他低耗能排程機制如SCA-ICA、Linux/Android內建管理機制，比較實際執行時的功耗差異，並探討調整功耗造成之效能變化。實驗結果指出，BPM-DFS與Linux Performance模式相比，可節省25%總功耗，與SCA-ICA相比可節省至21%總功耗，若Linux/Android最低耗能的的Linux Powersave模式相比，BPM-DFS可節省至約2%總功耗。

關鍵字

電源管理；動態頻率調整； Android ；多核心； Linux ；工作排程

並列摘要

As the growing functionality of modern hand-held devices, the requirement of system performance is increased. The multicore processors are widely adopted in the hand-held systems accordingly. Since the hand-held systems are powered by battery, the battery life will become the dominated limitation of these high-performance multicore hand-held devices. Therefore an efficient power management mechanism for hand-held multicore system is become important today. Conventional power management systems of embedded systems, such as Linux power CPU power manager, Android peripheral manager, adopt an automatic scheme to control the usage of peripheral operations and processor frequency. It can not consider the requirement of user, actually task loading, and power-on/shutdown processors in the multicore system, to meet the actual operating situation. Therefore, this paper propose a novel power management mechanism, called Bounded-Power Multi-core Dynamic Frequency Scaling (BPM-DFS), which integrates a system configuration selection algorithm, a task re-scheduling mechanism, and a predictive power model. According to the assigned power budget by the user, BPM-DFS can dynamically adjust the configuration of the multicore system to control the suitable alive core number, working frequency, and task reassignment, to achieve good performance and under the limitation of power consumption. The proposed BPM-DFS has been implemented on quad-core x86 Android system to compare the actual capabilities of other power management schemes, such as SCA-ICA, Linux/Android build-in power managers. The experimental results reveal that BPM-DFS can save 25 % power consumption than Linux performance mode; save 21% power consumption than SCA-ICA. It also can save 2% power consumption than the most low-power Linux operation mode, Linux powersave mode.

並列關鍵字

Task Scheduling ； Multi-core ； Linux ； Android ； Dynamic Frequency Scaling (DFS) ； Power Management

參考文獻

[1] C. Xian and Y.-H. Lu, “Dynamic voltage scaling for multitasking realtime systems with uncertain execution time,” in ACM Great Lakes Symp. VLSI (GLSVLSI), 2006, pp. 392–397.

[2] E. Talpes and D. Marculescu, “Toward a multiple clock/voltage island design style for power-aware processors,” IEEE Trans. Very Large Scale Integr. (VLSI) Syst., vol. 13, no. 5, pp. 591–603, 2005.

[3] G. Magklis, G. Semeraro, D. H. Albonesi, S. G. Dropsho, S. Dwarkadas, and M. L. Scott, “Dynamic frequency and voltage scaling for a multipleclock-domain microprocessor,” IEEE Micro, vol. 23, no. 6, pp. 62–68, 2003.

[4] Advanced Configuration and Power Interface,[Available Online]:http://www.acpi.info/

[7] Haisang Wu, Binoy Ravindran, E. Douglas Jenseny, and Peng Li, “CPU Scheduling for Statistically-Assured Real-Time Performance and Improved Energy Efficiency” , CODES+ISSS’04, September 8–10, 2004, Stockholm, Sweden.

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針對多核心Android系統之低耗能排程機制設計

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