[libvirt-users] Network speed between two guests on same host.

[Dominique Ramaekers]

Hi,

I've got two hosts. Most of my guests are Windows systems. I'm using LANBench to test network performance.

1) From an physical PC to a guest (it doesn't matter on which host), I get almost 1Gb/s. They are connected through a 1Gb/s swich => very good!

2) From a guest on one host to a guest on the other host => plusminus 1Gb/s => Okay!

3) Between two guests on the same host => plusminus 230Mb/s ???

The guests have network over a bridged interface, so I tried the same test over a NAT interface => The same 230Mb/s...

Is there a way to tweak connection speeds between two guest running on the same host?

Thanks in advance...

An piece of the xml dump of one of the guests:
<domain type='kvm' id='17'>
  <name>PCVIRTdra</name>
  <uuid>925e4f9b-2c27-406d-bdd9-f3e0b44f28bb</uuid>
  <title>PCVIRTdra - PC voor dra</title>
  <description></description>
  <memory unit='KiB'>2097152</memory>
  <currentMemory unit='KiB'>2097152</currentMemory>
  <memoryBacking>
    <hugepages/>
  </memoryBacking>
  <vcpu placement='static'>8</vcpu>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='x86_64' machine='pc-i440fx-utopic'>hvm</type>
    <bootmenu enable='yes'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <hyperv>
      <relaxed state='on'/>
      <vapic state='on'/>
      <spinlocks state='on' retries='8191'/>
    </hyperv>
  </features>
  <cpu mode='custom' match='exact'>
    <model fallback='allow'>cpu64-rhel6</model>
    <topology sockets='2' cores='2' threads='2'/>
  </cpu>
  <clock offset='localtime'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
    <timer name='hypervclock' present='yes'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <pm>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='no'/>
  </pm>
  <devices>
    ....
    <interface type='bridge'>
      <mac address='52:54:00:b1:41:b3'/>
      <source bridge='br0'/>
      <target dev='vnet4'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
.....