利用页面重构与数据温度识别的闪存缓存算法

基于闪存的固态盘(SSD)具有比磁盘更加优越的性能,并且在桌面系统中逐渐替代磁盘.但是,尽管在SSD中嵌入了DRAM作为缓存,闪存在不断写入的过程中也可能产生不稳定的写性能,主要是因为逻辑页写入时会频繁引发非覆盖写和垃圾回收操作.针对此问题,提出了一种叫作PRLRU的新型闪存缓存管理方法,通过页面重构机制以及数据温度识...

Constructing Cache Algorithm for Flash by Leveraging Page Reconstruction and Data Temperature Recognition

NAND flash based solid state disks(SSD)have better performance than magnetic disks and are gradually replacing hard disks in desktop systems.However,although DRAM is embedded in SSD as a buffer,SSD may also produce unstable write performance with continuous writing,because non-overwrite write and garbage collection(GC)operations are frequently triggered when physical pages are written.Aiming at this problem,a new flash buffer management strategy called PRLRU(least recently used algorithm by page reconstruction)is proposed,which manages the buffer through the page reconstruction mechanism and the data temperature recognition mechanism.The page reconfiguration mechanism combines pages with valid data that are less than one page size with other pages and then writes back to the flash memory to reduce the actual write operation by minimizing the number of non-overwrite write operations.The data temperature recognition mechanism performs temperature level marking on the cached pages,and then writes back the pages in a predetermined priority order.Test it with real workloads,the experimental results show that PRLRU can effectively improve SSD performance and prolong SSD lifetime.Compared with LRU,BPLRU and 2QW-Clock,the write performance of PRLRU is increased by 34.5%,22.8%and 28.8%,respectively on average,the read performance increased by 12.5%,10.6%and 8.3%,respectively on average,and the amount of garbage collection decreased by 10.5%,8.7%and 6.3%,respectively on average.