libvirt users - Nov 2015 - regard limiting network bandwidth

hi  all
i am a kvm , qemu  user newbie , i am  using libvirt and virsh to mange my KVM
VMs , i want to  limit the network bandwidth of each VM , i come across libvirt
 xml format option :
<forward mode='nat' dev='eth0'/>
  <bandwidth>
    <inbound average='1000' peak='5000'
burst='5120'/>
    <outbound average='128' peak='256'
burst='256'/>
  </bandwidth>to limit the bandwidth of each vm , however i have a
question how does these option applied limit on  kvm vm ?  through using of
linux cgroub or its a qemu network bandwidth  limit functionality ?  

On 03.11.2015 13:21, asw Anose wrote:
> hi  all
> i am a kvm , qemu  user newbie , i am  using libvirt and virsh to mange my
KVM VMs , i want to  limit the network bandwidth of each VM , i come across
libvirt  xml format option :
> <forward mode='nat' dev='eth0'/>
>   <bandwidth>
>     <inbound average='1000' peak='5000'
burst='5120'/>
>     <outbound average='128' peak='256'
burst='256'/>
>   </bandwidth>to limit the bandwidth of each vm , however i have a
question how does these option applied limit on  kvm vm ?  through using of
linux cgroub or its a qemu network bandwidth  limit functionality ?
> 
> 
This is currently implemented per nic calling set of 'tc' commands to
construct some structure that in the end limits the traffic through nic
as requested. If you want to get your hands dirty you may look over this:

http://libvirt.org/git/?p=libvirt.git;a=blob;f=src/util/virnetdevbandwidth.c;h=da3a0d327ea21879e2da5f10701015f38eec0297;hb=HEAD#l149

Michal