Open Stack

2014-03-03 23:44 GMT-03:00 Steve Gordon <sgordon at redhat.com>:

> ----- Original Message -----
> > Hi everyone,
> >
> > I'm currently taking part of a project at the Federal University of
> Campina
> > Grande called fogbow, which aims on providing an energy efficient
> scheduler
> > and an opportunistic compute node (which deactivates the service if the
> > host isn't idle) on top of openstack.
>
> Hi Marcos,
>

Hi Steve, thank you very much for the reply,

>
> This sounds like an interesting idea - have you had a look at the way this
> functionality is implemented in the oVirt (http://ovirt.org) scheduler
> [1] in case there are any ideas there that could be leveraged? I believe
> the determination there is also made by examining pCPU load (albeit with
> some additional computations applied) though it does not use powernap.
>

Regarding oVirt, thanks for the pointer. We'll take a look on how it
implements this feature.


>
> > Regarding the opportunistic aspect of the project, we're planning on
> using
> > powernap (http://manpages.ubuntu.com/manpages/lucid/man8/powernap.8.html
> )
> > to tell if the host is idle or not.
> >
> > Finally, my question is: what do you guys think would be the best way
> for a
> > powernap action script to interact with nova-compute in order to stop all
> > running instances and disable the host?
>
> If I understand correctly your suggestion here is that the powernap action
> script would run when powernapd on the host has determined it to be at low
> CPU usage at which point it would stop the instances and disable/poweroff
> the host, rather than having one of the other nova components monitor the
> load and initiate the required action?
>

Actually we want nova-compute to run opportunistically, in the sense that
it should *only* run when the host is idle. Btw, by reading my previous
message again, I realized it doesn't seem very clear.


>
> > Would killing and respawning the nova-compute be an elegant way of doing
> > that in your opinion? Or do RPC calls sound better?
>
> Is the desire necessarily to *stop* all instances, or evacuate/migrate
> them to another host so that you can consolidate instances on a subset of
> your compute hosts and either power the remainder down and/or disable the
> compute service on them? Another consideration here might be how much
> available pCPU you want to keep as a buffer in case of a burst in instance
> activity (probably something to make configurable?)?
>

Instances' migration is definitely a desirable feature, but we are not
putting much effort on this for now. When we notice that the host is being
actively used by a local user, we want to simply kill all running instances.



>
> Thanks,
>
> Steve
>
> [1] http://www.ovirt.org/Features/oVirtSchedulerAPI#Balance
>
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