libvirt users - Mar 2016 - Re: Incorrect memory usage returned from virsh

When I run `virsh dominfo <domain>` I get the following:

Id:             455
Name:           instance-000047e0
UUID:           50722aa0-d5c6-4a68-b4ef-9b27beba48aa
OS Type:        hvm
State:          running
CPU(s):         4
CPU time:       123160.4s
Max memory:     33554432 KiB
Used memory:    33554432 KiB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: apparmor
Security DOI:   0
Security label: libvirt-50722aa0-d5c6-4a68-b4ef-9b27beba48aa (enforcing)

The domain is not at 100% memory capacity. How can I diagnose this further?

On 03/18/2016 01:36 PM, Connor Osborn wrote:
> When I run `virsh dominfo <domain>` I get the following:
> 
> Id:             455
> Name:           instance-000047e0
> UUID:           50722aa0-d5c6-4a68-b4ef-9b27beba48aa
> OS Type:        hvm
> State:          running
> CPU(s):         4
> CPU time:       123160.4s
> Max memory:     33554432 KiB
> Used memory:    33554432 KiB
That says that the host allows up to 32G memory to be consumed by the
guest, and that no ballooning has taken place so the guest is free to
use it all.  It doesn't mean that the guest is actually using it, though.
> The domain is not at 100% memory capacity. How can I diagnose this further?
You're asking the wrong interface.  dominfo only tells you how much of
the memory balloon is in use (here, none), and does not ask how much
memory the guest claims to be using.

'virsh memtune' and 'virsh dommemstat' ask different questions,
and may
be able to give you more insight into the guest's current memory usage
(but it might also be something you can't learn without guest cooperation).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

Thanks for the clarification. I will probe more into dommemstat.

On Fri, Mar 18, 2016, 3:21 PM Eric Blake <eblake@redhat.com> wrote:
> On 03/18/2016 01:36 PM, Connor Osborn wrote:
> > When I run `virsh dominfo <domain>` I get the following:
> >
> > Id:             455
> > Name:           instance-000047e0
> > UUID:           50722aa0-d5c6-4a68-b4ef-9b27beba48aa
> > OS Type:        hvm
> > State:          running
> > CPU(s):         4
> > CPU time:       123160.4s
> > Max memory:     33554432 KiB
> > Used memory:    33554432 KiB
>
> That says that the host allows up to 32G memory to be consumed by the
> guest, and that no ballooning has taken place so the guest is free to
> use it all.  It doesn't mean that the guest is actually using it,
though.
>
> > The domain is not at 100% memory capacity. How can I diagnose this
> further?
>
> You're asking the wrong interface.  dominfo only tells you how much of
> the memory balloon is in use (here, none), and does not ask how much
> memory the guest claims to be using.
>
> 'virsh memtune' and 'virsh dommemstat' ask different
questions, and may
> be able to give you more insight into the guest's current memory usage
> (but it might also be something you can't learn without guest
cooperation).
>
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>
>