SMP Virtualization Performance Evaluation

Multiprocessor virtual machines (VMs) allow guest operating systems to use symmetric multiprocessing (SMP) in a VM. However, the use of SMP in a VM complicates CPU scheduling by the virtual machine monitor and can significantly increase the performance overhead of virtualization. This paper analyzes the performance of SMP virtualization used in two leading virtualization systems: VMware ESX 3.5 and Xen 3.2. Each is analyzed using single-threaded (SPEC CPU2006 445.gobmk) and multithreaded (SPEC OMP2001 332.ammp m) CPU bound workloads to measure how the virtualization overhead scales when running SMP VMs. ESX has more overhead, but performs equally well for both singlethreaded and multithreaded workloads. Xen has almost no virtualization overhead for single-threaded workloads, but performs poorly with synchronized multithreaded workloads.