A reuse distance based precopy approach to improve live migration of virtual machines

Virtualization enables data centers to share physical resources between virtual private servers (VPS) cost-effectively. Live migration of virtual machines (VM) is one of the most important capabilities that have been provided by the virtualization. It enables the data center´s administrators to apply the load balancing properly. Sending large number of VM´s memory pages wastes the data center´s bandwidth. It also decreases the quality of service during live migration. By reducing the number of sent pages, live migration time is reduced. Using an effective approach for sending VM´s pages leads to shorter downtime and migration time compared to pre-copy. This paper proposes an algorithm for tracking updated memory pages and making decision for transferring dirty pages during each iterated migration phase. In this paper, the concept of reuse distance is adopted to reduce the transferring number of dirtied pages. According to the experimental results, when the system is under heavy workload or running applications inside the VM are write-intensive; the reuse-distance approach has better performance than traditional pre-copy in terms of the number of transferred pages, total migration time and downtime. Experiments show that with increasing workload, reduction in the number of sent pages reaches 68% without increasing systems´ overhead during live migration.