一种基于双窗口的NAND闪存缓冲区管理算法

A NAND Flash Buffer Management Algorithm Based on Double Windows

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。

To improve the life and storage performance of NAND Flash,a NAND Flash buffer management algorithm called double windows least recently used(DW-LRU)was proposed based on double windows.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.In addition,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 algorithms of LRU,LRU-write sequence reordering(LRU-WSR),and probability of reference LRU(PR-LRU),the proposed algorithm can respectively improve the buffer hit rate by an average of 16.8%,12.3%,2.8%.DW-LRU improves the buffer hit ratio,reduces the number of write operations,and the runtime of the algorithm.