faster: Xen or qemu+kvm?

[Felipe Alfaro Solana]

On 1/2/07, Mihamina Rakotomandimby
<mihamina.rakotomandimby at etu.univ-orleans.fr> wrote:
> Hi,
> Question for those who tried:
> Who is faster: Xen or qemu+kvm?

With no doubt at all, Xen is faster than anything else on earth. Xen
implements paravirtualization which requires support from the OS or,
in the case of operating systems that can't be modified (like the
family of Windows pseudo-operating systems), Xen requires hardware
assistance (in the form of processor extensions called Pacifica for
AMD and VT for Intel). Thus, the paravirtualized OS and Xen act
together to provide the most optimal performance possible.

Other full virtualization solutions (like QEMU, VMware, etc.) are
inherently slower since the gues OS runs unmodified and it requires a
lot of "magic" being done by the hypervisor to virtualize hardware and
privileged access.