A Directory Access Accelerating Mechanism Of NVM File Systems

Memory computing provides a new computing model for current big data computing,putting all data in non-volatile memory to help with data calculations,and exploiting highspeed computing performance for large-scale computing.However,the storage of data on the traditional memory medium is power-off,so many memory systems are still based on the design of disk I / O,which greatly limits the performance of memory computing.Non-volatile memory is a low-read,low-power,non-volatile storage medium that can replace traditional external memory and be handled in the same way as normal memory.Therefore,how to design a file system suitable for non-volatile memory has become a new challenge.The academic community has developed several new non-volatile memory-based file systems.The optimization of these new file systems mainly focuses on the structural optimization of metadata,the storage of file data,and the mechanism of consistency guarantee.They rarely optimize the directory access mechanism.The traditional directory mechanism can not effectively utilize the advantages of non-volatile memory.Therefore,how to improve the directory access mechanism of the non-volatile memory file system is the main focus of this paper.There are two kinds of traditional directory mechanisms: a multi-level directory tree mechanism and a fullpath directory mechanism.Both of these mechanisms are designed and implemented based on the disk I/O,and cannot utilize the characteristics of non-volatile memory.The mechanism of a multi-level directory tree mechanism introduces a large amount of redundancy overhead,such as recursive scan of the parent directory and tight coupling of metadata and directory entries.The full path directory mechanism introduces a lot of renaming overhead,especially in disk file systems.The overhead of this renaming greatly affects the overall performance of the system.In this paper,a multi-level directory tree mechanism and a full-path directory mechanism are comprehensively analyzed,and a new directory access mechanism(ADAM)for non-volatile memory file systems is proposed.ADAM optimizes the storage of file directory entries,and utilizes the byte addressing nature of non-volatile memory to store directory entries of files in an directory space(AFDN)manner,which reduces the latency of directory entry access.In the mechanism of this paper,we perceive the state of the file,and propose an adaptive migration strategy to dynamically adjust the partition of the directory space so that the file system can adapt to the mutual changes of the different states of the file during the operation and reduce the file.The cost of renaming.In addition,this paper analyzes the indexing mechanism of the storage system,and designs a hybrid indexing mechanism.This mechanism can efficiently utilize the mixed architecture mode of common memory(DRAM)and non-volatile memory(NVM),which reduces the index of files.Overhead,improving the overall performance of the system.Finally,we conducted a variety of experimental test file access,including the creation and deletion of catalog files and common files.Experimental results show that ADAM can greatly improve the access performance of the file system.The file access latency can be reduced up to 43%.This paper also tests the effect of the adaptive migration strategy of the directory space.Under the same file system and experimental conditions,the strategy proposed in this paper can greatly reduce the overhead of the system rename operation.In addition,for different delays of non-volatile memory,we conducted a number of experiments,the experimental results show that the ADAM mechanism proposed in this paper can be more stable to different NVMs than other non-volatile memory file system.