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DPM: A Demand-driven Virtual Disk Prefetch Mechanism for Mobile Personal Computing Environments

In this paper, we propose a demand-driven virtual disk (VD) prefetch mechanism-DPM to improve the performance of virtual machine (VM) at destination site for mobile personal computing environments. DPM uses an optimized COW (Copy-on-Write) virtual block device to split the traditional one-piece large-sized VD image into multiple small-sized SVDs (Software Virtual Disk) at a basic granularity of a single kind of software. Based on the fine-grained VD splitting, DPM uses an access frequency and priority-based prefetch target identifying-APTI algorithm to identify the SVDs of the being-used software by the user in real-time mode at destination site, and prefetches those SVDs by utilizing P2P transportation mechanism at background. We have built a prototype to realize DPM on Xen virtual machine monitor (VMM). Experiments on the prototype show that DPM can effectively improve the VM performance at an unexpected destination site without any cached VD state, supporting agile mobility of personal computing environments.