Suspend-aware Segment Cleaning in Log-structured File System

Abstract

The suspend feature of the modern smart device practically suppresses the background segment cleaning of the log-structured file system. In this work, we develop Suspend-aware Segment Cleaning for the log-structured file system. We seamlessly integrate the segment cleaning into the suspend module of the smartphone OS so that the log-structured file system can reclaim the free segments without interfering with the foreground user activity. The Suspend-aware Segment Cleaning consists of two key ingredients: (i) Virtual Segment Cleaning and (ii) Utilization-based Segment Cleaning. We implement Suspend-aware Segment Cleaning in commodity smartphone which uses the log-structured file system, F2FS, as its stock file system (Moto G). F2FS with Suspend-aware Segment Cleaning consolidates 6 more segments than stock smartphone does. With Suspend-aware Segment Cleaning, the F2FS consolidates 2 more segments even with suspend mode on than the case where the phone is always on.