Persistent memory(PM)file systems have been developed to achieve high performance by exploiting the advanced features of PMs,including nonvolatility,byte addressability,and dynamic random access memory(DRAM)like perfo...Persistent memory(PM)file systems have been developed to achieve high performance by exploiting the advanced features of PMs,including nonvolatility,byte addressability,and dynamic random access memory(DRAM)like performance.Unfortunately,these PMs suffer from limited write endurance.Existing space management strategies of PM file systems can induce a severely unbalanced wear problem,which can damage the underlying PMs quickly.In this paper,we propose a Wear-leveling-aware Multi-grained Allocator,called WMAlloc,to achieve the wear leveling of PMs while improving the performance of file systems.WMAlloc adopts multiple min-heaps to manage the unused space of PMs.Each heap represents an allocation granularity.Then,WMAlloc allocates less-worn blocks from the corresponding min-heap for allocation requests.Moreover,to avoid recursive split and inefficient heap locations in WMAlloc,we further propose a bitmap-based multi-heap tree(BMT)to enhance WMAlloc,namely,WMAlloc-BMT.We implement WMAlloc and WMAlloc-BMT in the Linux kernel based on NOVA,a typical PM file system.Experimental results show that,compared with the original NOVA and dynamic wear-aware range management(DWARM),which is the state-of-the-art wear-leveling-aware allocator of PM file systems,WMAlloc can,respectively,achieve 4.11×and 1.81×maximum write number reduction and 1.02×and 1.64×performance with four workloads on average.Furthermore,WMAlloc-BMT outperforms WMAlloc with 1.08×performance and achieves 1.17×maximum write number reduction with four workloads on average.展开更多
Flash memory has limited erasure/program cycles. Hence, to meet their advertised capacity all the time, flash-based solid state drives (SSDs) must prolong their life span through a wear-leveling mechanism. As a very...Flash memory has limited erasure/program cycles. Hence, to meet their advertised capacity all the time, flash-based solid state drives (SSDs) must prolong their life span through a wear-leveling mechanism. As a very important part of flash translation layer (FTL), wear leveling is usually implemented in SSD controllers, which is called internal wear leveling. However, there is no wear leveling among SSDs in SSD-based redundant array of independent disks (RAIDs) systems, making some SSDs wear out faster than others. Once an SSD fails, reconstruction must be triggered immediately, but the cost of this process is so high that both system reliability and availability are affected seriously. We therefore propose cross-SSD wear leveling (CSWL) to enhance the endurance of entire SSD-based RAID systems. Under the workload of random access pattern, parity stripes suffer from much more updates because updating to a data stripe will cause the modification of other all related parity stripes. Based on this principle, we introduce an age-driven parity distribution scheme to guarantee wear leveling among flash SSDs and thereby prolong the endurance of RAID systems. Furthermore, age-driven lc,arity distribution benefits performance by maintaining better load balance the life span and performance of SSD-based RAID. With insignificant overhead, CSWL can significantly improve both展开更多
The unbanlanced updating frequency of data reduces the endurance of the whole non-volatile main memory that affects the system’s stability significantly. Wear-leveling techniques are effective methods to increase the...The unbanlanced updating frequency of data reduces the endurance of the whole non-volatile main memory that affects the system’s stability significantly. Wear-leveling techniques are effective methods to increase the endurance of non-volatile memory. In this paper, we propose a pure software based low cost wear-leveling method, called writing balance aware mandatory rewriting insertion optimization(WBAMRI), to improve the dynamic wear-leveling techniques.This method uses the mandatory rewriting operation combined with simple dynamic wear-leveling techniques to switch the code area to hot area dynamically. From the result of simulation, we can see that: 1) Compared with dynamic wear-leveling techniques, our ware-leveling method makes the endurance of non-volatile memory 6 times longer; 2) Compared with static wear-leveling techniques, our method nearly gets the same endurance but without the complex hardware design and the lose of memory access performance.展开更多
基金Project supported by the National Natural Science Foundation of China(No.62162011)the Doctor Funds of Guizhou University,China(Nos.2020(13)and 2022(44))。
文摘Persistent memory(PM)file systems have been developed to achieve high performance by exploiting the advanced features of PMs,including nonvolatility,byte addressability,and dynamic random access memory(DRAM)like performance.Unfortunately,these PMs suffer from limited write endurance.Existing space management strategies of PM file systems can induce a severely unbalanced wear problem,which can damage the underlying PMs quickly.In this paper,we propose a Wear-leveling-aware Multi-grained Allocator,called WMAlloc,to achieve the wear leveling of PMs while improving the performance of file systems.WMAlloc adopts multiple min-heaps to manage the unused space of PMs.Each heap represents an allocation granularity.Then,WMAlloc allocates less-worn blocks from the corresponding min-heap for allocation requests.Moreover,to avoid recursive split and inefficient heap locations in WMAlloc,we further propose a bitmap-based multi-heap tree(BMT)to enhance WMAlloc,namely,WMAlloc-BMT.We implement WMAlloc and WMAlloc-BMT in the Linux kernel based on NOVA,a typical PM file system.Experimental results show that,compared with the original NOVA and dynamic wear-aware range management(DWARM),which is the state-of-the-art wear-leveling-aware allocator of PM file systems,WMAlloc can,respectively,achieve 4.11×and 1.81×maximum write number reduction and 1.02×and 1.64×performance with four workloads on average.Furthermore,WMAlloc-BMT outperforms WMAlloc with 1.08×performance and achieves 1.17×maximum write number reduction with four workloads on average.
基金Supported by the National High Technology Research and Development 863 Program of China under Grant No.2013AA013201the National Natural Science Foundation of China under Grant Nos.61025009,61232003,61120106005,61170288
文摘Flash memory has limited erasure/program cycles. Hence, to meet their advertised capacity all the time, flash-based solid state drives (SSDs) must prolong their life span through a wear-leveling mechanism. As a very important part of flash translation layer (FTL), wear leveling is usually implemented in SSD controllers, which is called internal wear leveling. However, there is no wear leveling among SSDs in SSD-based redundant array of independent disks (RAIDs) systems, making some SSDs wear out faster than others. Once an SSD fails, reconstruction must be triggered immediately, but the cost of this process is so high that both system reliability and availability are affected seriously. We therefore propose cross-SSD wear leveling (CSWL) to enhance the endurance of entire SSD-based RAID systems. Under the workload of random access pattern, parity stripes suffer from much more updates because updating to a data stripe will cause the modification of other all related parity stripes. Based on this principle, we introduce an age-driven parity distribution scheme to guarantee wear leveling among flash SSDs and thereby prolong the endurance of RAID systems. Furthermore, age-driven lc,arity distribution benefits performance by maintaining better load balance the life span and performance of SSD-based RAID. With insignificant overhead, CSWL can significantly improve both
基金Supported by the Natural Science Foundation of Jiangsu Province(15KJB520019)High Level Talent Project of"Six Talents Summit"in Jiangsu Provincethe Priority Academic Program Development Project of Jiangsu Higher Education Institution
文摘The unbanlanced updating frequency of data reduces the endurance of the whole non-volatile main memory that affects the system’s stability significantly. Wear-leveling techniques are effective methods to increase the endurance of non-volatile memory. In this paper, we propose a pure software based low cost wear-leveling method, called writing balance aware mandatory rewriting insertion optimization(WBAMRI), to improve the dynamic wear-leveling techniques.This method uses the mandatory rewriting operation combined with simple dynamic wear-leveling techniques to switch the code area to hot area dynamically. From the result of simulation, we can see that: 1) Compared with dynamic wear-leveling techniques, our ware-leveling method makes the endurance of non-volatile memory 6 times longer; 2) Compared with static wear-leveling techniques, our method nearly gets the same endurance but without the complex hardware design and the lose of memory access performance.