Hi, this weekend I took a closer look at KVM. I think that the paravirtualized XEN or Hyper-V-Approach is superior to the full virtualization. Red Hat 6 will have XEN-Support (propably XEN 3.4 with power-consumption savings). The only drawback is that you need modified Kernels for paravirtualization to work. Fully virtualized systems might be simpler if you have a very mixed environment without dedicated Administrators for every operating system. Kind regards Nils > -----Original Message----- > From: centos-virt-bounces at centos.org > [mailto:centos-virt-bounces at centos.org] On Behalf Of Filipe > Brandenburger > Sent: Monday, September 14, 2009 9:24 PM > To: Discussion about the virtualization on CentOS > Subject: Re: [CentOS-virt] High CPU usage when running a > CentOSguestinVirtualBox > > Hi, > > On Mon, Sep 14, 2009 at 11:18, Dennis J. > <dennisml at conversis.de> wrote: > > On 09/14/2009 04:53 PM, Akemi Yagi wrote: > >> On Mon, Sep 14, 2009 at 7:24 AM, Hildebrand, Nils, 232 > <Nils.Hildebrand at bamf.bund.de> wrote: > >>> KVM uses a para-virtualized approach? > >> > >> Not at this moment according to this Red Hat virtualization guide: > > > > Ugh, I guess that means my plans to switch from Xen to KVM have to > > wait until RHEL 6 is released. > > I don't believe KVM will *ever* support para-virtualization > in the same sense that Xen does. > > For instance, see this FAQ in KVM's website: > http://www.linux-kvm.org/page/FAQ#What_is_the_difference_betwe > en_KVM_and_Xen.3F > > I believe the point is that current support for VT in recent > processors is good enough to be able to run VMs with a native > kernel at the same speed that could only be achieved with a > para-virtualized kernel before. Therefore, the > para-virtualized approach is being discontinued as "a hack" > and the tendency is to improve VM technologies to run native > code only. > > On the other hand, there is now talk about para-virtualized > device drivers, which mean drivers that are optimized to run > in a VM environment, which I believe are important in getting > good performance from native kernels in VMs. The same concept > exists in Xen, when you run Windows in Xen you do it using > HVM (non-para-virtualized) mode, in which case you will only > get good performance by loading the Xen drivers on the > Windows machine, I believe the concept is the same there. > > HTH, > Filipe > _______________________________________________ > CentOS-virt mailing list > CentOS-virt at centos.org > http://lists.centos.org/mailman/listinfo/centos-virt >