A common benchmark request at Phoronix lately has been to compare the Xen PV (para-virtualization) performance to Xen HVM (Hardware-assisted virtualization). Well, now that Ubuntu 14.04 LTS has been released, here's some benchmarks from within Amazon's EC2 compute cloud when comparing Ubuntu 14.04 Server PV and HVM instances.
Xen has long supported para-virtualization (PV) as its means of virtualization support for best performance and stability while minimizing overhead between Dom0 and the hypervisor by the two operating system software stacks working more closely together. The "newer" option for Xen virtualization users is to act as a hardware-assisted virtual machine (HVM) whereby the host and guest kernels don't need to be patched, Windows can run as a HVM guest, and there's complete hardware isolation.
Generally speaking, for a single server performance the Xen PV method traditionally offered greater raw performance, but we have somenew PV vs. HVM benchmarks to share today. Amazon offers HVM and PV operating system options for the popular Linux distributions and for most instance types. With Amazon HVM instances, para-virtualization is still used for networking and storage drivers for improved performance. PV has traditionally been the recommended choice for instances within Amazon EC2, but as of late there's been more interest and recommendations around using HVM.
For today's benchmarks, we deployed an Amazon EC2 c3.large instance using Ubuntu Server 14.04 LTS PV and Ubuntu Server 14.04 LTS HVM. The c3.large instance is rated for 7 ECUs, provides 2 vCPUs, 3.75GB of memory, and is backed by dual 16GB SSDs. When deploying both the HVM and PV instances, they were running on Intel Xeon E5 2680 (Sandy Bridge EP) v2 2.80GHz CPUs.
Ubuntu 14.04 LTS on both the PV and HVM instances were configured the same with the Linux 3.13.0-24-generic x86_64 kernel, GCC 4.8.2, and using an EXT4 file-system. Xen 4.2 provided the underlying virtualization capabilities.
All of our Xen PV vs. HVM virtualization benchmarking was done in a fully-automated, reproducible, and extensible manner using the open-source Phoronix Test Suite benchmarking software.
Let's see the results from this brief Xen PV vs. HVM benchmarking that was done over the weekend in Amazon's cloud.