Android經過多年的考驗逐漸成熟，現在許多智慧型手機或平板電腦都採用此系統，使用者逐漸增加。此系統是使用在行動裝置上，為了防震、省電等需求，所以採用快閃記憶體當作儲存元件。但快閃記憶體在資料覆寫時必須要先做抹除的動作，而每個區塊有抹除次數的限制，所以需要有耗損均衡演算法來做管理，讓抹除次數平均分散在每個區塊。Hot-Cold File Filter可偵測出經常修改的檔案，耗損均衡演算法利用此資訊可有效減少記憶體的使用量，除此之外，還可用在許多地方。例如：在混合式儲存裝置的應用，系統必須將常用的檔案放在速度較快的儲存裝置上，以加速存速度，而Hot-Cold File Filter可提供常用檔案的資訊，應用在這技術上。在此篇研究中，我們將Hot-Cold File Filter實作的更完整，在Kernel內實作List儲存熱檔案資訊，上層應用程式也可以透過我們實作的Library來快速取得熱檔案資訊。最後實驗會再呈現Hot-Cold File Filter的效能和Overhead的分析還有使用我們的Library開發出的應用程式。這些實驗都是在Nexus7平台上實機測量，可觀察實際使用情形。實驗結果顯示Hot-old File Filter可以正常的運作，也可判斷出熱資料，且測量出的Overhead也不大，說明了這個架構是有可行性。

Android system is widely used in smartphones and tablet PCs, and many people use the system in their daily lives. Because smartphones and tablet PCs should consider energy consumption and device size into designing, flash memory is a suitable storage medium for the devices. According to the previous studies, we know that hot files could have an important impact on the flash memory (i.e., the wear-leveling algorithm and hybrid storages). In the thesis, we will implement a hot-cold file filter in the Android system. We add a hot file list and an Android library to the hot-cold file filter. With the hot file list and library, developers can quickly get information about hot files and help upper applications to use. In the experiments, we have built an Android kernel in a real mobile device, and run the hot-cold file filter in the device. We can also demonstrate the hot-cold file filter will not cause significant overhead and can correctly reflect the real information about hot files.

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