隨著科技的進步，手機的功能也日益增加，近年來成為人們生活中不可或缺的物品；除此之外人們與手機的互動性也逐漸增加，更大量地使用社群軟體、遊戲等等，造成使用者對於手機效能、電池壽命的需求也逐漸增大。DVFS是在使用過程當中調整手機CPU頻率的一種方法，調整頻率通常是根據當下的硬體狀況作調整，達到省電的效果，然而這種方法並沒有考慮到手機與使用者互動的狀況。在這篇論文當中，我們針對社群軟體Facebook，透過蒐集使用過程中資料，發現使用者的互動行為與手機硬體變化的關係，並建立一套新的調整頻率方法實際在Android系統上執行。實驗過程與現有的手機的調整機制做比較，結果發現新的機制僅增加CPU 3.43%使用率、可達到9.2%省電效果。

With the fast growing technology, the abilities of smartphones become more. In recent years, smartphone is one of the necessities in our daily life. Besides, people tend to use interactive application on their smartphones, such as, social network application, game. People become more care about their smartphone performance and battery life. DVFS (Dynamic voltage and frequency scaling) is an efficient energy saving policy while using smartphones. The policy of frequency scaling usually based on the hardware workload to achieve energy saving. However, this method does not consider the user interaction with the smartphone. In this paper, we collect the user behavior and CPU usage during using Facebook and find out the correlation. Our studies indicate that user behavior would influence the CPU usage during using smartphones. We also implement a user-based policy to scale CPU frequency. Our experiment result shows that it would have 9.2% energy saving and only increase 3.43% CPU usage.

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