Research On Lightweight Dynamic Lazy Page Wear-leveling Mechanism

The emerging non-volatile memory devices(NVM,Non-volatile Memory)have the advantages of durability,byte addressing,high integration,low energy consumption,and low price.They have a broader development prospect than traditional memory devices such as DRAM.However,the NVM device cell generally can only withstand 10⁸?10¹² writes,which is far less than the service life of traditional DRAM devices.The uneven distribution of the application load also accelerates the aging of the device.How to ensure the service life of the NVM device is one of the difficulties in current application research.In view of the problems of high additional write overhead,poor adaptability of different applications,and low universality after modification of the hardware architecture in existing NVM device wear-leveling schemes,a lightweight dynamic lazy page wear-leveling mechanism based on the hot page identification technology of write load capacity is proposed(LDL-WL for short).It is loaded in the form of a shared library,and the change of the PTE's soft-dirty bit in the Linux system is used to obtain the write counts increment of the page.It designs and implements a hashmap mapping slots structure to store data related to counting.Different from the existing wear leveling scheme that uses the change of write frequency as the migration threshold,it is proposed to use the index of the page's write load capacity to evaluate the current load operating state rather than predict the future write change.It solves the problems of low migration gain,high additional writes,and poor ability to adapt to different applications in the current page wear mechanism.The benchmark is based on no-swap without a wear leveling scheme.The fixed-swap,quail and the proposed LDL-WL were compared and tested.The results show that the fixed-swap scheme has the strongest dependence on the set threshold.LDL-WL and quail have similar performance overhead,but LDL-WL can better balance the write operation of NVM devices.The average standard deviation of the write distribution of fixed-swap,quail and LDL-WL schemes is reduced by 41%,80%and 91%.The additional write overhead is24%,14%and 3%respectively,and the additional execution time is 16%,11%and 4%respectively.Compared with the no-swap,fixed-swap,and quail schemes,the average write times of NVM devices in the LDL-WL scheme are reduced by 86%,57%,and 11%.