While benchmarks are a very difficult exercie and as such the results must be considered carefully, they are still interesting to compare the respective performance between the solutions for different workloads.

This page will try to keep an eye on the relative performance of Xen and KVM. Until 2.6.25, virtio was not part of the mainstream linux kernel, so the tests compared performance of HVM systems (the guest system was an "unmodified OS").

Future tests should continue to test hvm performance as they are obviously important for OS without Paravirtualized drivers, but also try to add to the picture the benefits of paravirtualized drivers (PV xen, virtio) and even PV CPU in the case of Xen.

The kernel compilation tests should use kernbench instead of "make clean && make allnoconfig && time make" as it provide a statistical value.

13 Feb 2008

Intel system

Tests on an Intel based system with an Intel Core2 2Ghz and 2GB RAM. The test VM for both Xen and KVM is the same image: an unmodified Debian Lenny kernel 2.6.22 amd64 w/512 MB RAM

The test is still the "make clean && make allnoconfig && time make" of a 2.6.24 kernel

• Host is an opensource Xen-3.2 (from xen.org) with a Dom0 running a kernel-2.6.18.8-xen, Dom0 userspace is a 64bits Ubuntu Feisty

dbench 10: 243 MB/s

• Host is a Ubuntu feisty amd64 kernel 2.6.20 and KVM 60

dbench 10: 255 MB/s

• Result on host Ubuntu feisty amd64 kernel 2.6.20 (not in a VM)

dbench 10: 505 MB/s

AMD system

Tests on an AMD based system with an AMD X2 4400+ and 4GB RAM. The test VM for both Xen and KVM is the same image: an unmodified Debian Lenny kernel 2.6.22 amd64 w/512 MB RAM

The test is still the "make clean && make allnoconfig && time make" of a 2.6.24 kernel

• Host is an opensource Xen-3.2 (from xen.org) with a Dom0 running a kernel-2.6.18-xen, Dom0 userspace is a 64bits Ubuntu Gutsy

• Host in Ubuntu gutsy amd64 kernel 2.6.22-14-generic with KVM 60

12 Feb 2008

Thanks for Dan Berrange who pointed me on xen.org instead of xensource.com as a source of download for the latest Xen.

The tests consists of the compilation of a linux kernel 2.6.24 with allnoconfig (make allnoconfig && time make). The host hardware is a 1.86Ghz Intel Core2duo.

unmodified VM: 64bits Debian Etch

The first two tests run the same Virtual Machine with an unmodified 64bits Debian Etch.

• Host is an opensource Xen-3.2 (from xen.org) with a Dom0 running a kernel-2.6.18-xen, Dom0 userspace is a 64bits Debian Lenny

• Host is a 64bits Debian Lenny with a 2.6.24 kernel and KVM-60

paravirtualised VM: 64bits Debian Etch with xenified kernel

The following test runs on the same hardware than the previous one. The kernel used in the DomU is the same as in Dom0:

• Host is an opensource Xen 3.2 (from xen.org) with a Dom0 running a kernel-2.6.18-xen, Dom0 userspace is a 64bits Debian Lenny

11 Feb 2008

For the following 2 tests, the system is an Intel core 2 duo 2.4Ghz w/ 2GB RAM running the latest available versions:

• for Xen: opensource Xen 3.1.0 (from xen.xensource.com) + Dom0 kernel based on kernel.org 2.6.18
• for KVM: kvm-60 on a 2.6.23

The guest used in both case is the exact same VM (non-paravirtualised 64 bit Debian etch with 256 MB RAM).

Guest system boot-up time

Kernel compilation benchmark

Time to compile a 2.6.24 allnoconfig

• first try - cold cache

• second try - w/ cache