Research Of Post-Copy Algorithm Based Live Virtual Machine Migration

Virtual machine dynamic migration technology is one of the key technologies of virtualization,and virtual machine dynamic migration technology can realize load balance,system fault tolerance,on-line maintenance and energy management and other functions.At present,there are two kinds of live virtual machine algorithms,Post-Copy and Pre-Copy.Post-Copy algorithm is better than Pre-Copy algorithm in the amount of network transmission and total migration,but Post-Copy algorithm makes the virtual machine's execution time longer than Pre-Copy algorithm because of the frequently missing pages on target node.This thesis presents a Post-Copy algorithm based on the AMPX(memory Prefecting in Xen adaptive)page for the Post-Copy frequent page problem.Firstly,this thesis introduces pre-execution mechanism aiming at the problem of frequent page fault when the Virtual Machine recovery on the target mode.The source host pre-executes the Virtual Machine while transferring a minimal portion of the address space(the currently-accessed code,stack,and data pages)to the destination node.In this way,the source host accurately predicts the memory pages which will be accessed by the destination host,and reducing the page fault rate obviously.Secondly,according to the memory pages which are visited by Virtual Machine in pre-execution period on the source,this thesis presents AMPX algorithm which bases on the locality principle of program.This algorithm not only can dynamically adjust the predict page according to the lack of the target host,but also can adjust the number of pages dynamically according to the running environment of the current target host.Through this algorithm can improve the page prediction accuracy and reduce the destination host's page fault rate.Finally,this thesis realizes the Post-Copy algorithm based on AMPX page prediction by analyzing the flow of Post-Copy algorithm.This thesis chose the HPC Challenge(HPCC)benchmark suite to evaluate the performance of AMPX.The results show that the Post-Copy algorithm based on AMPX page prediction outperforms the standard Post-Copy algorithm both in total migration time and in page fault rate.