Data Correlation Aware Buffer Cache Management for Improved I/O Performance on Log-Structured File System-based NAND Flash Storage Devices

Buffer cache was critical in bridging the access speed gap between main memory and disks. Conventional buffer cache management approaches focus on improving the cache hit ratio by exploiting the locality of I/O workloads. However, conventional buffer caching strategies do not take the write characteristics of log-structured file systems into consideration, and thus they would suffer from a poor cache hit ratio as well as the degraded I/O performance. This study proposes a novel buffer cache management strategy at SSD controllers to improve the data caching performance. It takes advantages of the I/O pattern of log-structured file systems, e.g., F2FS, by correlating the current block I/O address with its previous I/O address such that the I/O requests issued to the same file location can be efficiently managed by the buffer cache. Experimental results demonstrate that the proposed approach substantially improve the read I/O performance by 14.5%, write I/O performance by 92.4%, and enhance the flash lifetime by 92.0%.