I've just found this:

domiftune domain interface-device [[--config] [--live] | [--current]] [--inbound average,peak,burst] [--outbound average,peak,burst]
Set or query the domain's network interface's bandwidth parameters. interface-device can be the interface's target name (<target dev='name'/>), or the MAC address.
If no --inbound or --outbound is specified, this command will query and show the bandwidth settings. Otherwise, it will set the inbound or outbound bandwidth. average,peak,burst is the same as in command attach-interface.

If --live is specified, affect a running guest. If --config is specified, affect the next boot of a persistent guest. If --current is specified, affect the current guest state. Both --live and --current flags may be given, but --current is exclusive. If no flag is specified, behavior is different depending on hypervisor.


I'm gonna try it.

I thought the edit command was to perform on-the-fly editing of VMs 
I should have read the manual :)

On 13/feb/2013, at 14:58, Michal Privoznik <mprivozn@redhat.com> wrote:

On 13.02.2013 14:55, Davide Guerri wrote:
On 13/feb/2013, at 14:53, Eric Blake <eblake@redhat.com> wrote:

On 02/13/2013 04:17 AM, Davide Guerri wrote:

Which particular QoS settings in the XML are you trying to change, so I
can point out which virsh command is the hotplug for that setting?  For
example, 'virsh memtune' can be used to hotplug in new values for the
<memtune> XML element.


bandwidth, inbound and outbound

Thanks!

D.


I haven't gone through the code to tell for sure, but for now you can
only set the network part of QoS (via virsh net-update) while the
domain's interface is not supported yet. However, patches are welcome :)


Michal