[arch-general] qemu-kvm vs. qemu upstream

Mauro Santos registo.mailling at gmail.com
Thu Feb 24 12:32:30 EST 2011

On 24-02-2011 17:07, C Anthony Risinger wrote:

> hmm, soo qemu doesn't actually use the VT extensions?  wtf is the
> point then?  this is what i don't understand; if qemu supports KVM via
> the `-enable-kvm` switch why does it suck so much -- it seems just as
> slow to me as no KVM support at all.  I have a server that runs
> several KVM/libvirt instances (windows being one of them purely for
> ... i dont even know) so i'm pretty familiar with it all, but i'm just
> trying to get solid info why there is such a huge performance gap when
> the both "use KVM".  i thought KVM itself did all the VT handling.
> C Anthony

AFAIK qemu-kvm is the 'plain' qemu patched to have a more up-to-date and
complete kvm support. At least it's what is on the great arch wiki [1] :p

There are also other small tweaks, such as kvm support being enabled by
default in qemu-kvm so you don't need to specify -enable-kvm, it will
still fallback to using emulation is kvm support is not found or can't
be used.


Mauro Santos

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