While benchmarks are a very difficult exercice 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.
22 Jul 2008
All tests where realised on the same system :AMD X2 4400+/4GB RAM/sata drive.
Host is running Ubuntu Desktop 8.04 amd64, kernel 2.6.24-19-generic (when values are given for the host, it was started with mem=3072M) All the runs with the guests use the same image based on a basic install of ubuntu server 8.04 amd64, with 3072M and smp 2.
Versions of the KVM module (manually compiled against host kernel) is either 70 or 71 (default is 71 when non specified)BR Version of Xen is 3.3 unstable retrieved from git (7 Jul 2008)
| kvm hvm | kernel 2.6.24-16-server |
| kvm hvm virtio | same as above, booted using -drive file=<image>,if=virtio,boot=on (initrd contains modules virtio_pci, virtio_blk) |
| xen hvm | kernel 2.6.24-16-server, same as kvm hvm above |
| xen pv | kernel 2.6.18.8-xen (same as Dom0), same image as all vm above |
dbench 3.04
The best of 2 runs for dbench 10
| platform | Throughput in MB/sec | % of native |
| host (native) | 544.403 | 100 |
| kvm vm | 543.041 | 100 |
| kvm virtio disk cache=on | 567.623 | 104 |
| kvm virtio disk cache=off | 574.813 | 106 |
| xen hvm | 522.167 | 96 |
| xen pv | 365.44 | 67 |
kernbench 0.42
One run of kernbench -M (available memory being below 4GB)
Results present time in s at load -j 8 with standard deviation being in parenthesis
| platform | Elapsed Time | System Time | User Time | Percent CPU | Context Switches | Sleeps | Elapsed time /native |
| host (native) | 54.214 (0.174442) | 93.348 (0.266964) | 10.634 (0.265104) | 191 (0.707107) | 17898.4 (65.9758) | 13341.8 (39.8522) | 1.00 |
| kvm vm (kvm 70) | 84.664 (0.397781) | 107.48 (0.501348) | 53.692 (0.234883) | 190 (0.707107) | 15756.4 (66.4139) | 16633.6 (92.4868) | 1.56 |
| kvm vm (kvm 71) | 84.158 (0.16769) | 107.826 (0.307782) | 52.924 (0.33894) | 190.6 (0.547723) | 15754 (50.2544) | 16518.6 (71.8213) | 1.57 |
| kvm virtio disk cache=on | 83.676 (0.461877) | 107.838 (0.766988) | 52.13 (1.02242) | 190.8 (0.447214) | 15650 (68.4142) | 16515.2 (107.183) | 1.54 |
| kvm virtio disk cache=off | 89.41 (0.91169) | 110.73 (0.976627) | 57.85 (1.06104) | 188 (0.707107) | 16143.6 (55.9178) | 16746.2 (38.2583) | 1.65 |
| xen hvm | 101.046 (6.3364) | 127.176 (5.13701) | 55.446 (1.5455) | 181.2 (16.331) | 17114.4 (613.934) | 16993.8 (388.987) | 1.86 |
| xen pv | 62.812 (0.458443) | 94.474 (0.592182) | 20.082 (0.387001) | 182 (1.22474) | 9545.2 (39.6573) | 10872.2 (78.1326) | 1.12 |
| xen dom0 | 60.924 (0.43558) | 94.616 (0.261687) | 20.294 (0.282011) | 188.4 (1.34164) | 10330 (232.204) | 10976.2 (86.9897) | 1.12 |
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
| run | 1 | 2 | 3 |
| real | 2m34 | 2m24 | 2m25 |
| user | 1m23 | 1m22 | 1m22 |
| sys | 1m0 | 1m0 | 1m1 |
dbench 10: 243 MB/s
- Host is a Ubuntu feisty amd64 kernel 2.6.20 and KVM 60
| run | 1 | 2 | 3 |
| real | 2m12 | 2m13 | 2m12 |
| user | 1m27 | 1m28 | 1m27 |
| sys | 0m43 | 0m43 | 0m43 |
dbench 10: 255 MB/s
- Result on host Ubuntu feisty amd64 kernel 2.6.20 (not in a VM)
| real | 1m31 |
| user | 1m11 |
| sys | 0m10 |
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
| run | 1 | 2 | 3 |
| real | 2m28 | 2m17 | 2m16 |
| user | 1m27 | 1m27 | 1m27 |
| sys | 0m51 | 0m49 | 0m49 |
- Host in Ubuntu gutsy amd64 kernel 2.6.22-14-generic with KVM 60
| run | 1 | 2 | 3 |
| real | 2m31 | 2m29 | 2m29 |
| user | 1m36 | 1m36 | 1m36 |
| sys | 0m52 | 0m53 | 0m52 |
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
| run | 1 | 2 | 3 |
| real | 2m26 | 2m19 | 2m20 |
| user | 1m21 | 1m22 | 1m21 |
| sys | 1m02 | 0m58 | 1m00 |
- Host is a 64bits Debian Lenny with a 2.6.24 kernel and KVM-60
| run | 1 | 2 | 3 |
| real | 2m11 | 2m07 | 2m07 |
| user | 1m26 | 1m26 | 1m26 |
| sys | 0m45 | 0m40 | 0m40 |
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
| run | 1 | 2 | 3 |
| real | 1m34 | 1m33 | 1m33 |
| user | 1m17 | 1m18 | 1m18 |
| sys | 0m15 | 0m15 | 0m15 |
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
| platform | time in seconds |
| Xen | 23 |
| KVM | 20 |
Kernel compilation benchmark
Time to compile a 2.6.24 allnoconfig
- first try - cold cache
| platform | real time | user time | sys time |
| Xen | 1m53 | 1m06 | 0m43 |
| KVM | 1m03 | 1m06 | 0m33 |
- second try - w/ cache
| platform | real time | user time | sys time |
| Xen | 1m52 | 1m07 | 0m43 |
| KVM | 0m56 | 1m07 | 0m31 |