Re: [Xen-users] Why HVM?

Frédéric VANNIÈRE
Tue, 31 Aug 2010 08:40:28 -0000

Hello,

Le 27 août 2010 à 08:41, Jonathan Tripathy a écrit :
> I''ve noticed some VPS hosting companies offering a Xen
"HVM" option. What are the advantages of a Linux HVM VPS over a PV
one?

I''m working for a hosting company and seriously considering switching
to HVM instead of PV.

We are using PV x86_64 linux guests for several years (100+ VMs) and
I''ve just discovered that PV guest where very bad on some benchmarks
involving many process creation (unixbench).

The Host : Xeon L5530 (HT disabled) , 24 GB mémory
The guest : 4 vCPUS, 20 GB memory.

Unixbench  :     host = 4000,       PV guest = 1500,        HVM guest = 3900


With modern CPUs (Xeon 5500 and 5600 here) and new PV drivers on the guest
(Linux 2.6.36)  HVM gives very low overhead and the performances of HVM guests
are very closed to PV guests.

With HVM you can use Remus and memory sharing.



Regards,

Frederic.