MultiCache: Multilayered Cache Implementation for I/O Virtualization

摘要

As the virtual machine technology is becoming the essential component in the cloud environment, VDI is receiving explosive attentions from IT market due to its advantages of easier software management, greater data protection, and lower expenses. However, I/O overhead is the critical obstacle to achieve high system performance in VDI. Reducing I/O overhead in the virtualization environment is not an easy task, because it requires scrutinizing multiple software layers of guest-to-hypervisor and also hypervisor-to-host. In this paper, we propose multilayered cache implementation, called MultiCache, which combines the guest-level I/O optimization with the hypervisor-level I/O optimization. The main objective of the guest-level optimization is to mitigate the I/O latency between the back end, shared storage, and the guest VM by utilizing history logs of I/O activities in VM. On the other hand, the hypervisor-level I/O optimization was implemented to minimize the latency caused by the "passing I/O path to the host" and the "contenting physical I/O device among VMs" on the same host server. We executed the performance measurement of MultiCache using the postmark benchmark to verify its effectiveness.