[Openstack-operators] User Survey usage of QEMU (as opposed to KVM) ?

Kashyap Chamarthy kchamart at redhat.com
Wed May 11 15:51:58 UTC 2016

On Tue, May 03, 2016 at 02:27:00PM -0500, Sergio Cuellar Valdes wrote:


> I'm confused too about the use of KVM or QEMU In the computes the
> file​/etc/nova/nova-compute.conf has:
> virt_type=kvm
> The output of:
> nova hypervisor-show <id> | grep hypervisor_type
> is:
> hypervisor_type           | QEMU

As Dan noted in his response, it's because it is reporting the libvirt driver
name (which is reported as QEMU).

Refer below if you want to double-confirm if your instances are using KVM.

> The virsh dumpxml of the instances shows:
> <domain type='kvm' id='44'>

That means, yes, you using KVM.  You can confirm that by checking your QEMU
command-line of the Nova instance, you'll see something like "accel=kvm":

	# This is on Fedora 23 system
	$ ps -ef | grep -i qemu-system-x86_64
	[...] /usr/bin/qemu-system-x86_64 -machine accel=kvm [...]

> ....
> <emulator>/usr/bin/qemu-system-x86_64</emulator>
> ​But according to ​this document [1], it is using QEMU emulator instead of
> KVM, because it is not using /usr/bin/qemu-kvm
> So I really don't know if it's using KVM or QEMU.

As noted above, a sure-fire way to know is to see if the instance's QEMU
command-line has "accel=kvm".

A related useful tool is `virt-host-validate` (which is part of libvirt-client
package, at least on Fedora-based systems):

   $ virt-host-validate | egrep -i 'kvm'
    QEMU: Checking if device /dev/kvm exists                                   : PASS
    QEMU: Checking if device /dev/kvm is accessible                            : PASS

> [1] https://libvirt.org/drvqemu.html


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