異質雙核心嵌入式即時系統之有效低能源消耗排程演算法

Abstract

近年來，異質雙核心嵌入式即時系統，如個人數位助理及手機越來越受到歡迎。為了達到即時以及低能源的耗損，低能源消耗排程成為一個值得重視的研究課題。大多數現有低能源消耗排程的動態電壓調整演算法，其目標多在單一CPU或是在同質性的多核心系統上。本論文中，在異質性的雙核心嵌入式即時系統上，我們提出一個較長共同執行時間(LCET)演算法，以適用在具動態電壓調整能力的異質雙核心。本演算法包含兩個階段：第一，運用所提出的排班演算法來縮短在異質雙核心嵌入式即時系統上的工作總執行時間；第二，我們更進一步探討利用縮短過後的總執行時間來調整電壓及頻率以達到低能量的耗損。模擬結果顯示，相較於Kim et al. 方法，在使用(不使用)動態電壓調整之下，我們所提出的方法分別在可插隊的LCET (P-LCET)及不可插隊的LCET (NP-LCET)，各節省了8%及16% ~ 25% (13%及33% ~ 38%)的總能量耗損。

In recent years, heterogeneous dual-core embedded real-time systems, such as personal digital assistants (PDAs) and cellular phones, have become more and more popular. In order to achieve real time performance and low energy consumption, low power scheduling becomes a critical issue. Most researches on low power scheduling with dynamic voltage scaling (DVS) were targeted at only one CPU or homogeneous multi-core systems. In this thesis, we propose a low power scheduling algorithm called Longer Common Execution Time (LCET) for DVS enabled heterogeneous dual-core embedded real-time systems, which includes two steps. First, we reduce total execution time of tasks by using LCET in heterogeneous dual-core embedded real-time systems. Second, we further exploit the reduced total execution time to adjust voltage and frequency levels in order to reduce the total energy consumption. Simulation results show that the proposed P-LCET (a preemptive version) and NP-LCET (a non-preemptive version) can effectively reduce the total energy consumption by 8% and 16% ~ 25% (13% and 33% ~ 38%) compared with the work by Kim et al. with (without) dynamic voltage scaling.