A computing device includes a storage device in which a program for operating a file system is stored, and a processor configured to execute the program stored in the storage device wherein, in response to execution of the program, if a write request upon a file to be stored in the storage device is generated, the processor calculates, based on one or more file write methods included in the file system, an overhead of each of the one or more write methods, selects a file write method having the smallest overhead among the one or more file write methods, and records the file in the storage device by using the selected file write method, the one or more file write methods include slack space recycling (SSR), internal-segment-copying-based garbage collection and external-segment-copying-based garbage collection.