Greedy page replacement algorithm for flash-aware swap system

Abstract

Because of the attractive features, flash memory replaces magnetic disk as swap storage. All page write operations to flash-memory-based swap storage are requested during the page replacement algorithm in terms of swapping out dirty pages to obtain free page frames. Due to out-of-place update scheme, intensive write operations could result in using up the flash-memory-based swap storage quickly and incurring frequent garbage collection operations with high energy consumption. Moreover, the cost of flash page write operation is much higher than that of flash page read operation. Therefore, in this paper, we propose a greedy page replacement algorithm, called GDLRU, for flash-aware swap system. In order to reduce the number of flash page write operations, GDLRU introduces a clean-aware victim page selection method called CPS which evicts clean page preferentially. If there is no clean page, CPS evicts the dirty page with the least dirty data preferentially. To further reduce the number of flash page write operations, GDLRU also introduces a clean-aware victim page update scheme called CPU which only writes back the dirty flash pages within the victim dirty page. The simulation results indicate that our proposed algorithm outperforms other existing page replacement algorithms in terms of replacement cost.