Efficient and intelligent garbage collection policy for NAND flash-based consumer electronics

Abstract

Because NAND flash memory provides the out-of-place update scheme to address its erase-before-write hardware constraint, garbage collection policy is included in the flash-aware file systems and flash translation layer (FTL) to reclaim garbage and obtain free space. In this paper, an efficient and intelligent garbage collection policy is proposed for NAND flash-based consumer electronics, which is called EIGC. EIGC introduces an efficient grey prediction model for forecasting the future I/O workload during the next garbage collection operation execution time interval and determines the number of victim blocks that should be selected for evicting according to the predicted I/O workload. In order to reduce the cleaning cost in terms of the cost for copying the valid pages to the free space of NAND flash memory and improve the degree of wear leveling, an efficient victim block selection scheme is included in the proposed EIGC policy. Trace-driven simulations show that the proposed EIGC policy is superior to the state-of-the-art policies in terms of the number of copy operations, the number of erase operations, and the degree of wear leveling.