Scalable and Efficient Reinforcement Learning for Virtual Machine Rescheduling in Cloud Data Centers

Managing a vast number of virtual machines (VMs) efficiently is a critical challenge in modern large-scale data centers. The continuous creation and termination of VMs lead to resource fragmentation across physical machines (PMs), necessitating periodic VM rescheduling to optimize resource utilization. Despite its significance, VM rescheduling has received limited attention in the literature. A key challenge is that, unlike conventional combinatorial optimization problems, the efficiency of rescheduling algorithms is heavily impacted by inference time, as VM states evolve dynamically during execution. This scalability bottleneck hampers existing methods. To address this, we propose VMR$^{2}$L, a reinforcement learning framework tailored for VM rescheduling. VMR$^{2}$L integrates a two-stage decision-making process to accommodate complex operational constraints, a feature extraction mechanism that captures critical relational information for rescheduling, and a risk-aware evaluation strategy that enables users to balance execution speed and rescheduling accuracy. Extensive experiments using real-world data from a production-scale data center demonstrate that VMR$^{2}$L achieves near-optimal performance while reducing inference time to a matter of seconds.