LinuxVirt:

This table compares the features and performance of the various virtualization technologies available for Linux. Hopefully this table also explains why many Linux distributions today ship Xen, even though UML and KVM are upstream and lhype is getting pretty close to inclusion into the upstream kernel.

For an explanation of the technologies, please see the [:TechOverview:technology overview] page.

If you spot something that is not up to date, or think of something missing, feel free to update this page.

full virt

paravirt

license

x86

x86-64

IA64

PPC

s390

performance

SMP guests

notes

Xen

(./)

(./)

GPL

(./)

(./)

(./)

(./)

paravirt very fast, full virt slow/medium

(./)

full virt needs VT / AMD-V

KVM

(./)

GPL

(./)

(./)

still slow

requires VT / AMD-V, upstream

lhype

(./)

GPL

(./)

slow/medium

rhype

(./)

(?)

(./)

(./)

(./)

fast

(?)

research project

MoL

(./)

GPL

(./)

fast

32 bit only

UML

(./)

GPL

(./)

(./)

??

(./)

slow

upstream

qemu

(./)

GPL

(./)

(./)

??

(./)

slow/medium

runs in userspace, kQEMU not GPL

OpenVZ

GPL

(./)

(./)

(./)

(./)

very fast

shared kernel

VServer

GPL

(./)

(./)

(./)

(./)

very fast

shared kernel, no performance isolation

VMware

(./)

proprietary

(./)

(./)

medium

(./)

LPAR

(./)

proprietary

(./)

native

(./)

z/VM

(./)

(./)

proprietary

(./)

very fast

(./)

typically runs under LPAR

PHYP

(./)

proprietary

(./)

fast

(./)

used on all modern IBM System p

lv1

(./)

proprietary

(./)

fast

(./)

used on Sony PS3

BEAT

(./)

proprietary

(./)

fast

(?)

used on Toshiba CellEB

Notes:

  1. Paravirtualization is fundamentally faster than full virtualization, with the exception of the userspace implementation in UML.
  2. For an overview of the other benefits of paravirtualization, see ParavirtBenefits.

  3. Full virtualization performance in KVM and Xen is largely limited by the overhead of trap & emulate. Emulating multiple instructions at once at the time of a trap should bring it up to speed with VMware.

  4. OpenVZ (Virtuozo) and VServer are not virtualization technologies per se. They carve up a single system in "super chroot" jails. All the containers run on top of the same kernel.
  5. Qemu can emulate different guest architectures, eg. running an x86 virtual machine on a PPC guest. Qemu also has the distinction of being the only full virtualization technology that can run without root privileges.
  6. Parts of Qemu are used in the full virtualization implementations of Xen and KVM.

LinuxVirt: TechComparison (last edited 2006-12-29 06:16:48 by arnd)