Live migration of virtual machines relocates running VM across physical hosts with unnoticeable service downtime. However, propagating changing VM memory at low cost, especially for write-intensive applications or at relatively low network bandwidth, is still uncovered. This paper presents Microwiper, an improvement of memory propagation in live migration. Our idea is twofold. We propose ordered propagation to transfer dirty memory pages according to their rewriting rates. We factor available network bandwidth in sending pages to throttle hot spot; after the accumulated rewriting rate exceeds the estimated bandwidth, next iteration is started immediately. The combination of these novel methods can not only reduce dirtied pages, but also shorten service downtime and total migration time. We implemented Microwiper by retrofitting the pre-copy approach in Xen hypervisor. We conducted detailed experiments to evaluate its efficacy on various workloads. The experimental results show that Microwiper can significantly reduce downtime and transferred pages by more than 50%. Microwiper has good adaptivity, and hence can be applied to other virtualization platforms easily.
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