[virt-tools-list] How is CPU Usage % Calculated

[Richard W.M. Jones]

On Tue, Sep 28, 2010 at 04:27:02PM -0700, Tyrel Datwyler wrote:
> Hi,
> 
> Can anybody tell me how virt-manager calculates CPU Usage %? I'm
> assuming the difference in cpuTime obtained from libvirt for a virtual
> server over some interval.
> 
> cpuTime2 - cpuTime1 / sample interval

Don't know about virt-manager, but for virt-top it is documented here:

http://people.redhat.com/~rjones/virt-top/faq.html#calccpu

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/