Supporting NUMA-Aware I/O in Virtual Machines

In a nonuniform memory access (NUMA) system, I/O to a local interconnect is more efficient than I/O to a remote interconnect. Managing resources of virtual machines (VMs) is complex in a virtualized NUMA system because multiple VMs are competing for CPU, memory, and devices spread across NUMA nodes. In this article, the authors study how to schedule VMs for better I/O on a NUMA system. They discuss the design of a NUMA-aware I/O hypervisor scheduler that aligns VMs and hypervisor threads on NUMA boundaries while extracting the most benefit from local device I/O.