[dpdk-dev] [PATCH v4 00/10] VM Power Management

[Carew, Alan]

Hi Thomas,

> Hi Alan,
> 
> Did you make any progress in Qemu/KVM community?
> We need to be sync'ed up with them to be sure we share the same goal.
> I want also to avoid using a solution which doesn't fit with their plan.
> Remember that we already had this problem with ivshmem which was
> planned to be dropped.
> 
> Thanks
> --
> Thomas
> 
> 
> 2014-10-16 15:21, Carew, Alan:
> > Hi Thomas,
> >
> > > > However with a DPDK solution it would be possible to re-use the
> message bus
> > > > to pass information like device stats, application state, D-state requests
> > > > etc. to the host and allow for management layer(e.g. OpenStack) to
> make
> > > > informed decisions.
> > >
> > > I think that management informations should be transmitted in a
> management
> > > channel. Such solution should exist in OpenStack.
> >
> > Perhaps it does, but this solution is not exclusive to OpenStack and just a
> potential use case.
> >
> > >
> > > > Also, the scope of adding power management to qemu/KVM would be
> huge;
> > > > while the easier path is not always the best and the problem of power
> > > > management in VMs is both a DPDK problem (given that librte_power
> only
> > > > worked on the host) and a general virtualization problem that would be
> > > > better solved by those with direct knowledge of Qemu/KVM
> architecture
> > > > and influence on the direction of the Qemu project.
> > >
> > > Being a huge effort is not an argument.
> >
> > I agree completely and was implied by what followed the conjunction.
> >
> > > Please check with Qemu community, they'll welcome it.
> > >
> > > > As it stands, the host backend is simply an example application that can
> > > > be replaced by a VMM or Orchestration layer, by using Virtio-Serial it
> has
> > > > obvious leanings to Qemu, but even this could be easily swapped out
> for
> > > > XenBus, IVSHMEM, IP etc.
> > > >
> > > > If power management is to be eventually supported by Hypervisors
> directly
> > > > then we could also enable to option to switch to that environment,
> currently
> > > > the librte_power implementations (VM or Host) can be selected
> dynamically
> > > > (environment auto-detection) or explicitly via rte_power_set_env(),
> adding
> > > > an arbitrary number of environments is relatively easy.
> > >
> > > Yes, you are adding a new layer to workaround hypervisor lacks. And this
> layer
> > > will handle native support when it will exist. But if you implement native
> > > support now, we don't need this extra layer.
> >
> > Indeed, but we have a solution implemented now and yes it is a
> workaround, that is until Hypervisors support such functionality. It is possible
> that whatever solutions for power management present themselves in the
> future may require workarounds also, us-vhost is an example of such a
> workaround introduced to DPDK.
> >
> > >
> > > > I hope this helps to clarify the approach.
> > >
> > > Thanks for your explanation.
> >
> > Thanks for the feedback.
> >
> > >
> > > --
> > > Thomas
> >
> > Alan.

Unfortunately, I have not yet received any feedback:
http://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg01103.html

Alan.