D'après la FAQ de Xen, il semblerait que la virtualisation hardware couplée à la paravirtualisation (pour les entrées/sorties) permette d'obtenir des performances quasi-natives sur processeurs Intel VT sans modifier l'OS invité. Mais ils ne donnent pas de chiffres vérifiables.
Q: How does Xen differ from other virtualization technologies?
A : [...] Xen runs unmodified guests such as Windows, on “the bare metal” at native processor speed on Intel VT enabled hardware. Paravirtualization in this case provides I/O performance that Intel VT cannot provide, while still using the best in hardware support for accelerated performance of virtualization.
Q: What is paravirtualization?
A : [...] For Windows and other guests that are unaware of Xen, the hardware virtualization of Intel VT, combined with paravirtualizing device drivers in Windows, allows Xen to achieve the same high level of performance as virtualized Linux guests.
Par contre, en paravirtualisation (donc sans assistance matérielle et avec modification du système invité), il y a des chiffres, et là Xen offre des performances quasi-natives.
[^] # Re: Performances de la virtualisation hardware
Posté par Frédéric Lopez . En réponse à la dépêche Xen 3.0.4 et la virtualisation matérielle. Évalué à 2.
Source : http://www.xensource.com/xen/xen/faqs.html
Q: How does Xen differ from other virtualization technologies?
A : [...] Xen runs unmodified guests such as Windows, on “the bare metal” at native processor speed on Intel VT enabled hardware. Paravirtualization in this case provides I/O performance that Intel VT cannot provide, while still using the best in hardware support for accelerated performance of virtualization.
Q: What is paravirtualization?
A : [...] For Windows and other guests that are unaware of Xen, the hardware virtualization of Intel VT, combined with paravirtualizing device drivers in Windows, allows Xen to achieve the same high level of performance as virtualized Linux guests.
Par contre, en paravirtualisation (donc sans assistance matérielle et avec modification du système invité), il y a des chiffres, et là Xen offre des performances quasi-natives.
Source : http://www.cl.cam.ac.uk/research/srg/netos/xen/performance.h(...)