No VT? No fair to *any* of the platforms reviewed.

The first generation of VT enabled hardware is not really focused on performance - it is more
about enablement - ie it allows you to run unmodified guests, with the minimal software
tricks. There are many ways to virtualize without hardware support and many of them will
outperform current VT hardware. eg paravirtualized Xen will easily outperform VT enabled
fullyvirtualized Xen. 2nd generation VT enabled hardware is starting to add some interesting
features (NPT on AMD, EPT on Intel) that can make a huge difference to performance bringing
fullyvirtualized guests closer to being on a par with paravirtualized ones. You still need to
have paravirtualized drivers inside your fullyvirtualized guests though - without it I/O will
be terrible. 

The article in question is really quite badly done. Plain QEMU is not really interesting
unless you need to do cross-architecture virtualization, eg PPC on x86 - no one will claim you
should use it for native x86 on x86 because emulation is simply never going to be fast enough.


KVM's future is very bright indeed, but if there's no VT then it reduces to just QEMU
emulation, so the review was rather worthless wrt to KVM. If you're talking state of art, then
KVM should be compared against Xen paravirt and Xen fullyvirt since that's the most commonly
used open source virt out there today, and for all its flaws Xen (eg not being in upstream
LKML) does work pretty well in terms of performance. 

Finally, paravirtualized drivers should be used in all tests, since I/O performance will
inevitably suck without it and anyone seriously deploying virtualization in production will
use paravirtualized drivers.