Stabilizing and boosting I/O performance for file systems with journaling on NVMe SSD  

作　　者：Lin QIAN Bin TANG Baoliu YE Jianyu WU Xiaoliang WANG Sanglu LU 

机构地区：[1]National Key Laboratory for Novel Software Technology,Nanjing 210023,China [2]State Grid Electric Power Research Institute,Nanjing 211000,China

出　　处：《Science China(Information Sciences)》2022年第3期91-105,共15页中国科学（信息科学）（英文版）

基　　金：supported in part by National Key R&D Program of China (Grant No. 2018YFB1004704);National Natural Science Foundation of China (Grant Nos. 61832005, 61872171);Natural Science Foundation of Jiangsu Province(Grant No. BK20190058);Key R&D Program of Jiangsu Province (Grant No. BE2017152);Science and Technology Program of State Grid Corporation of China (Grant No. 52110418001M);Collaborative Innovation Center of Novel Software Technology and Industrialization。

摘　　要：Many journaling file systems currently use non-volatile memory-express(NVMe) solid-state drives(SSDs) as external journal devices to improve the input and output(I/O) performance. However,when facing microwrite workloads, which are typical of many applications, they suffer from severe I/O fluctuations and the NVMe SSD utilization is extremely low. The experimental results indicate that this phenomenon arises mainly because writing back data to backend file systems on hard disk drives is much slower than journal writing, causing journal writing to frequently freeze because of the two-phase mechanism.We, therefore, propose a merging-in-memory(MIM) acceleration architecture to stabilize and boost the I/O performance for such journaling file systems. MIM employs an efficient data structure of hash-table-based multiple linked lists in memory, which not only merges random microwrites into sequential large blocks to speed up writebacks but also provides additional gains in terms of reducing the frequency of write addressing and object opening and closing. Using a prototype implementation in Ceph File Store, we experimentally show that MIM not only eliminates severe fluctuations but also improves the I/O operations per second by roughly 1×–12× and reduces the write latency by 75%–98%.

关 键 词：journaling file systems NVMe SSD microwrite merging hash table Ceph 

分 类 号：TP391.1[自动化与计算机技术—计算机应用技术]