http://virt.kernelnewbies.org/TechComparison
TechComparison
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,lguest and KVM are
upstream.
For an explanation of the
technologies, please see the technology overview
page.
If you spot something that
is not up to date, or think of something missing, feel free to update
this page.
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full virt
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paravirt
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containers (OS
virt)
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license
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architectures
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performance
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SMP guests
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CPU / memory
hotplug
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standalone host
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notes
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Xen
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GPL
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i686, x86-64, IA64,
PPC
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paravirt very fast,
full virt medium
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full virt needs VT
/ AMD-V
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KVM
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GPL
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i686, x86-64, IA64,
PPC, S390
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paravirt very fast,
full virt medium
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full and para virt
need VT / AMD-V, upstream
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lguest
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GPL
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i686
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slow/medium
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upstream
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rhype
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GPL
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i686, x86-64, PPC
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fast
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(?)
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research project
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MoL
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GPL
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PPC
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fast
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32 bit only
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UML
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GPL
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i686, x86-64, PPC
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slow
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upstream
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L4Linux
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GPL
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i686, ARM
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medium
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qemu
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GPL
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i686, x86-64, IA64,
PPC, ARM, MIPS, SPARC (kQEMU only i686/x86-64)
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slow, medium with
kQEMU
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OpenVZ
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GPL
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i686, x86-64, IA64,
PPC, SPARC
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native
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live migration
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Linux-VServer
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GPL
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all where linux
goes
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native
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poor performance
isolation
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VirtualBox
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GPL/proprietary
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i686, x86-64
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fast/very fast
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kernel module GPL,
RDP and USB support proprietary
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VMware Server
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proprietary
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i686, x86-64
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medium/fast
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needs proprietary
kernel modules
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VMware
Workstation/Player
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proprietary
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i686, x86-64
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medium/fast
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needs proprietary
kernel modules
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VMware ESX
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proprietary
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i686, x86-64
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fast/very fast
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LPAR
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proprietary
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s390
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native
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z/VM
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proprietary
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s390
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very fast
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typically runs
under LPAR
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PHYP
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proprietary
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PPC
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fast
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used on all modern
IBM System p
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lv1
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proprietary
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PPC
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fast
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used on Sony PS3
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BEAT
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proprietary
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PPC
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fast
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(?)
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used on Toshiba
CellEB
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Notes:
-
Paravirtualization is
fundamentally faster than full virtualization, with the exception of
the userspace implementation in UML.
-
Containers (OS-level
virtualization) is yet faster than paravirtualization, achieving the
native speed.
-
Performance can vary
wildly depending on workload. This page
assumes system call intensive applications, since "fair weather"
performance numbers are not very useful.
-
Memory and CPU hotplug
is mostly useful because it allows one to
run more virtual machines on a system simultaneously, adjusting the
amount of memory allocated to each guest depending on load.
-
For an overview of the
other benefits of paravirtualization, see ParavirtBenefits.
-
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.
-
OpenVZ (Virtuozzo) and
Linux-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.
-
OpenVZ (Virtuozzo) can
change memory and CPU quota during runtime, there is no real hotplug
since there are no guest kernels.
-
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.
-
Parts of Qemu are used
in the full virtualization implementations of Xen and KVM.
-
The standalone
host column indicates whether or not the hypervisor (or host OS,
in the case of VM) is booted before Linux. See the comparison
of hypervisor based vs. Linux based virtualization for the debate
on whether or not this is an advantage.
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