The Research On A Lightweight Object Persistence Technology Based On SCM

The process of data type conversion between dram and disk of program cost so much because of the volatile-persistent boundary and performance gap which in original computer storage system.The new emerging Storage Class Memory(SCM)combines feature of non-volatile and byte-addressable,it can be attached to memory bus directly and accessed by memory load/store instructions,these make program's data persistence on SCM directly to be possible,it eliminates the process of data type conversion from dram to disk(serialization)and the reverse process(structuralization),and also reduces cost of write amplify within block interface system.So it makes a big sense of research of lightweight object persistence technology based on SCM.This paper present a Lightweight Object Persistence Technology based on SCM(LOPT).Firstly,LOPT eliminates time of serialization and structuralization of program's data type conversion by abstracting SCM into object and map these objects to program's address space,it also provides a series of object programming interfaces to users to make program bypass redundant kernel layers and use load/store instructions to manipulate SCM objects directly to reduce parts of system calls' cost.Then,LOPT utilizes hierarchical method to manage SCM objects and adopt an object buffer in user space.this method reduces cost of system calls of object management effectively.Finally,LOPT takes full advantage of byte-addressable future and adopts fine-grained log which has 64 bytes log entry to reduce write amplify of original journal technology.LOPT also adopts Intel hardware primitives to keep data consistency of CPU cache and employs preallocation for each transaction to improve write speed by reducing cost of program's data consistency.In comparison with original program,LOPT can accelerate program's data process by reducing time of data construction 94%,96% and 75% for list,B-Tree and hash table data structure.In comparison with Berkeley DB,LOPT can reduce write latency from 5%to 72%.