一种基于双窗口的NAND闪存缓冲区管理算法

为提升NAND闪存使用寿命和存储性能,提出了一种基于双窗口的NAND闪存区管理算法DW-LRU。DW-LRU算法利用4个LRU链表来捕获访问次数和冷热特征,且根据访问新近度将页面分为了6类:冷干净页面、冷脏页面、旧热干净页面、非旧热干净页面、旧热脏页面、非旧热脏页面。算法在冷干净LRU链表上设置了一个静态窗口,避免最近写入缓存区中的冷干净页面被频繁置换出;在热脏LRU链表上设置了一个动态窗口,用来处理长时间没被访问的热脏页面。实验结果表明:与LRU、LRU-WSR、PR-LRU算法相比,DW-LRU算法缓冲区命中率平均提升了16.8%、12.3%、2.8%。DW-LRU算法可以提高缓冲区命中率,减少闪存写操作次数和算法运行时间。

A NAND Flash Buffer Management Algorithm Based on Double Windows

In order to improve the life and storage performance of NAND Flash, a NAND Flash buffer management algorithm called DW-LRU (Double Windows Least Recently Used) which is based on double windows is proposed. The proposed algorithm uses four LRU linked lists to capture the access frequency and cold/hot characters in the buffer. The buffer pages are divided into six categories by operation recency: cold clean pages, cold dirty pages, old hot clean pages, non-old hot clean pages, old hot dirty pages and non-old hot dirty pages. A static window is set to avoid frequent replacement of the cold clean pages written to the buffer recently. And a dynamic window is set to handle hot dirty pages that have not been accessed for a long time. The experimental results show that compared with LRU, LRU-WSR, PR-LRU, the proposed algorithm can improve the buffer hit ratio, reduce the number of write operations and the runtime of the algorithm.