Semantic-Aware Hot Data Selection Policy for Flash File System in Android-Based Smartphones

Flash memory has different characteristics from traditional hard disk drives. Therefore, the traditional file systems such as EXT4 are not well-optimized for flash memory storage. Recently, a flash memory-aware file system, called F2FS, is announced, which is based on the log-structured file system considering the poor random write performance of flash memory. Although F2FS uses a heuristic for separating hot and cold data, the heuristic is not aware of file type. In this paper, we observe the lifetime of different types of files in Android platform and propose a semantic-aware hot data selection policy for F2FS. Experimental results show that the proposed technique reduces the garbage collection cost by up to 31%.