An Efficient Garbage Collection Policy for Flash Memory Based Swap Systems

Abstract

Mobile computing devices use flash memory as a secondary storage because it has many attractive features such as small size, fast access speeds, shock resistance, and light weight. Mobile computing devices exploit a swap system to extend a limited main memory space and use flash memory as a swap system. Although flash memory has the attractive features, it should perform garbage collection, which includes erase operations. The erase operations are very slow, and usually decrease the performance of the system. Besides, the number of the erase operations allowed to each block is also limited. To minimize the garbage collection time and evenly wear out, our proposed garbage collection policy focuses on minimizing the garbage collection time and wear-leveling. Trace-driven simulations show that the proposed policy performs better than existing garbage collection policies in terms of the number of erase operation, the garbage collection time, total amount of energy consumption and the endurance of flash memory.