Counting sort for the live migration of virtual machines

The live migration of virtual machines is an important technique in the area of virtualization, and it has been used for load balancing, fault tolerance, and system maintenance in modern data centers, clusters, and cloud computing. The pre-copy algorithm is the most used method for the live migration of virtual machines. However, the existing problem of repeatedly transferring dirty memory pages leads the increase of the transferring data amount, delays of the total migration time as well as the downtime. By analyzing the iteration process of the pre-copy algorithm, we find that the transferring order of memory pages during every middle round has a huge impact on the generation and transferring of dirty memory pages. Further we put forward the concept of the live migration of virtual machines based on the counting sort. During every middle round of the iteration process, we do not transfer the memory pages according to their original order, instead we transfer the memory pages according to their times of being dirty. Experiment results show that with different workloads the counting sort method could simultaneously decrease the transferring data amount, the total migration time, and the downtime to improve the performance of the live migration.