[Libvir] Virtual networking

Daniel Veillard veillard at redhat.com
Wed Jan 17 11:50:47 UTC 2007


On Tue, Jan 16, 2007 at 07:35:37PM +0000, Daniel P. Berrange wrote:
> On Tue, Jan 16, 2007 at 07:09:30PM +0000, Daniel P. Berrange wrote:
> > On Tue, Jan 16, 2007 at 05:21:15PM +0000, Mark McLoughlin wrote:
> > >   - Or perhaps, libvirt would *always* talk to a daemon ... whether 
> > >     local or remote. That way you don't have the race condition where 
> > >     multiple apps can create a guest of the same name or uuid at once.
> > 
> > Possibly :-) I think I'll draw another diagram...
> 
> One way is to move the entire driver model out of libvirt and into a daemon,
> so that libvirt itself is just a very thin layer which marshalls APIs calls
> onto the wire. So whether local or remote the diagram looks the same:
> 
> http://people.redhat.com/berrange/libvirt/libvirt-arch-local-1.png
> http://people.redhat.com/berrange/libvirt/libvirt-arch-remote-3.png
> 
> Now you might say this will make the Xen stack inefficient, because there
> will be yet another daemon in the stack. This could certainly be true if
> the libvirt daemon only ever talked to XenD, but all our performance
> critical calls go straight to the HV. So when talking to a remote daemon
> I think libvirt -> libvirt daemon -> HV ought to be faster than libvirt ->
> XenD -> HV, simply by virtue of not involving python. It would also make
> it practical to run virt-manager as an unprivileged app even when managing
> the local Xen instance. So we could remove the need to su to root for
> the local instance.

  Hum, honnestly I would *really* prefer to avoid systematically going though
an RPC. No I don't like this idea, I prefer to keep the driver in libvirt
linked in the user's space. Thibgs which were dirt cheap become way more
expensive when they don't need to, this is a severe regression from a
library user standpoint.

Daniel

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Daniel Veillard      | virtualization library  http://libvirt.org/
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