Re: Suspending with kvm and kvm_loaded

[Muli Ben-Yehuda <muli-7z/5BgaJwgfQT0dZR+AlfA@public.gmane.org>]

On Sat, Jun 16, 2007 at 07:36:18PM +0200, Luca wrote:
> On 6/16/07, Richard Hughes <hughsient-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >On Sat, 2007-06-16 at 15:30 +0300, Muli Ben-Yehuda wrote:
> >>
> >> > Is there any easy way we can detect if virtual machines are running?
> >>
> >> The module use counts will be elevanted and they'll refuse to unload
> >> (or there's a nasty bug somewhere).
> >
> >Nahh, that's too brutal. Is there a way to (hypothetically) read:
> >
> ># cat /sys/module/kvm/parameters/number_of_running_vms
> >2
> 
> cat /sys/module/kvm_intel/refcnt (or kvm_amd) will tell you how many
> VMs are running.

... were running at the moment when you queried the kernel. Once you
get back the answer, it's irrelevant --- a new VM could've been
launched inbetween reading the refcnt and acting upon it. Really the
only safe way to do this sort of thing is to try and rmmod the module.

Cheers,
Muli

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