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Re: [Xen-users] who comes from kvm?

On Fri, 11 Feb 2011, Javier Guerra Giraldez wrote:

On Fri, Feb 11, 2011 at 12:24 PM, Steve Sapovits <steves06@xxxxxxxxxxx> wrote:
(Xen is a type 1, KVM is a type 2)

that's not exact since KVM doesn't run 'on top of' the Linux kernel;
it's part of the Linux kernel.  as such, it has the same 'bare metal'
access to hardware as the rest of the kernel or the Xen hypervisor.

IMHO, the main difference is that Xen has its own scheduler and
arbitration logic, while KVM reuses existing Linux code.  pro: it can
be tuned to the specific case of handling VMs.  con: a little
duplication of code

I second this. I have used KVM extensively and find it is very stable and useful in case we are running a dissimlar OS (like windows and SunOS). KVM is really good in a lot of respects (for eg:- in case of USB if you want to send a raw USB device to the guest machine). I have found KVM very stable. As Javier told, KVM is _not_ running on top of kernel. It is a totaly different sub-system and gives near-baremetal performance if properly configured with virtio drivers.

Almost everything which can be done on Xen can be done on KVM (but IMO vice-versa is not totally true).


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