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Thanks a lot for the useful information !

Cheers, Massimo

On Wed, Nov 28, 2018 at 10:20 PM Sean Mooney <smooney at redhat.com> wrote:

> On Wed, 2018-11-28 at 12:14 -0500, Jay Pipes wrote:
> > On 11/28/2018 10:38 AM, Massimo Sgaravatto wrote:
> > > Hi
> > >
> > > I was wondering if nova allows to get the CPUtime and wallclocktime
> > > consumed by a project in a certain time period, without using
> ceilometer
> > >
> > > Among the data returned by the command "openstack usage show" there is
> > > also a "CPU Hours" but, if I am not wrong, this is actually the
> > > WallClockTime. Did I get it right ?
> >
> > It's neither. It's the calculated time that the VM has been "up"
> > multiplied by the number of vCPUs the VM consumes.
> >
> > It's basically worthless as anything more than a simplistic indicator of
> > rough resource consumption.
> >
> > You can see how the calculation is done by following the fairly
> > convoluted code in the os-simple-tenant-usage API:
> >
> > This calculates the "hours used":
> >
> >
> https://github.com/openstack/nova/blob/62245235bc15da6abcdfd3df1c24bd856d69fbb4/nova/api/openstack/compute/simple_tena
> > nt_usage.py#L51-L82
> >
> > And here is where that is multiplied by the VM's vCPUs:
> >
> >
> https://github.com/openstack/nova/blob/62245235bc15da6abcdfd3df1c24bd856d69fbb4/nova/api/openstack/compute/simple_tena
> > nt_usage.py#L213
> >
> > > If so, it is also possible to get the CPUTime ?
> >
> > If you are referring to getting the amount of time a *physical host CPU*
> > has spent performing tasks for a particular VM, the closest you can get
> > to this would be the "server diagnostics" API:
> >
> >
> https://github.com/openstack/nova/blob/master/nova/api/openstack/compute/views/server_diagnostics.py
> >
> > That said, the server diagnostics API is a very thin shim over a
> > virt-driver-specific interface:
> >
> >
> https://github.com/openstack/nova/blob/62245235bc15da6abcdfd3df1c24bd856d69fbb4/nova/compute/manager.py#L4698
> >
> > The libvirt driver's get_server_diagnostics() (host-specific) and
> > get_instance_diagnostics() (VM-specific) implementation is here:
> >
> >
> https://github.com/openstack/nova/blob/62245235bc15da6abcdfd3df1c24bd856d69fbb4/nova/virt/libvirt/driver.py#L8543-L867
> > 8
> >
> > You might want to look at that code and implement a simple
> > collectd/statsd/fluentd/telegraf collector to grab those stats directly
> if you go the collectd route the libvirt plugin was modifed about 2 years
> ago to be able to use the domain uuid
> instaed the domain instance name when reporting stats and since we set the
> domain uuid to the nova uuid it makes it
> really easy to map back to the instance later. so ihink the colloectd
> libvirt plugin may be able to give you this info
> already and you can then just export that ot influxdb or gnnoci use later.
> the other monitoring solution can proably do
> the same but nova does not really track vm cpu usage that closely.
> > from the libvirt daemon on the compute nodes themselves.
> >
> > Best,
> > -jay
> >
>
>
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