A Measurement Study of ARM Virtualization Performance

ARM servers are becoming increasingly common, making server technologies such as virtualization for ARM of growing importance. We present the first in-depth study of ARM virtualization performance on ARM server hardware, including measurements of two popular ARM and x86 hypervisors, KVM and Xen. We show how the ARM hardware support for virtualization can support much faster transitions between the VM and the hypervisor, a key hypervisor operation. However, current hypervisor designs, including both KVM (Type 1) and Xen (Type 2), are not able to lever- age this performance benefit in practice for real application workloads. We discuss the reasons why and show that other factors related to hypervisor software design and implementation have a larger role in overall performance than the speed of micro architectural operations. Based on our measurements, we discuss changes to ARM's hardware virtualization support that can potentially bridge the gap to bring its faster virtual machine exit mechanism to modern Type 2 hypervisors running real applications. These changes have been incorporated into the latest ARM architecture