| Virtualization is a hot topic in current research. Through virtualization，it is possible to reducethe space occupied by the physical infrastructure, achieve dynamic management of the entire servercomputing assets pool and reduce data center energy demand.All these can cut the cost and lowerthe demand for energy.As one ofthe important applications of cloud computing, the live migration of virtualmachine(VM) can move a VM from one host to another without shutting it down. The key of livemigration is to reduce the total migration time and its downtime.This paper focuses on the processesof live migration of virtual machine and the Pre-copy algorithm used in memory migration. Opensource project Xen is the experimental platform.Current Pre-copy algorithm transfers too many zero pages which reduces the transmissionefficiency. Besides, default algorithm does not work well when memory pages are dirtiedrapidly.Dirtied pages are transferred repeatedly until it reaches the maximum number ofiteration.All these lead to longer total migration time and downtime.To solve these problems, thispaper proposes the ZRLE(Zero Run Length Encoding) first round of iteration compressionalgorithm and DPDT(dirty page delayed transfer) algorithm. Later analysis and experiments showthat the ZRLE first round of iteration compression algorithm can reduce the overall time of livemigration effectively. Besides, the improved DPDT algorithm reduces the total migration time anddowntime efficiently with a high dirtying page rate environment. |
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