A Scalable Signalling Mechanism for VM Migration with SR-IOV over Infiniband

Single Root I/O Virtualization (SR-IOV) is a promising I/O virtualization approach for achieving high performance in the virtualization over InfiniBand (IB) network. One challenge is related to the hardware address assignment for each virtual IB device. There are two schemes for the hardware address assignment, static assignment and dynamic assignment. Static assignment always preserves the hardware address of a virtual IB device that is attached to a VM, but the dynamic assignment does not. A drawback, however, using static assignment is that its communication will be disconnected after VM migration. In this paper, we point out the problem related to SR-IOV over IB that breaks the network connections after VM migration when the static assignment is deployed. Then, we propose a signalling mechanism that can maintain the network connectivity after VM migration. The performance evaluation using an experimental test bed shows that the proposed signalling mechanism does not increase the service downtime during hot migration. We also optimize the signalling method, where the same event can only be forwarded to a physical server once regardless of the hosted VMs, to reduce the management message overhead from O(n*m) to O(n).