Network Speed Test (IPerf) in KVM (Virtio-net, emulated, vt-d)

Note: Some of the numbers are too big, so the numbers on top of the bars shows their actual number. So they won't mess up the scale.

Summary of Results:

• One should use Virtio in favor of VT-d pass-through, or emulated Network Driver
• Emulated NICs are much slower than Virtio or VT-d
• The MAX bandwidth of Virtio connecting to a remote is very close to VT-d or Native
• Using Virtio to connect to Dom0 is much faster than using VT-d (since in our setup VT-d is a second NIC)
  

Type of Setup:

[a] Emulation (rtl8139)
Emulating an rtl8139 100Mbps-NIC, this is the default if you don't change anything with virt-install. (I.E. eucalyptus might get this one).

[b] Emulation (e1000)
Emulating an e1000 1Gbps-NIC, set in libvirt xml file, which produces a "-net nic,macaddr=xxx,vlan=0,model=e1000" in kvm arguements.

[c] VT-d (e1000 PCI Passthrough)
Passing a e1000 NIC from host to guest via VT-d. Need to be specified at virt-install "--host-device=pci_8086_3a20" (otherwise you need to handle the complex pci driver loading/unloading), where "pci_8086_3a20" is the name of the NIC. Use lspci -v and virsh nodedev-list to see them.

[d] Virtio
Using the virtio_net driver, set in libvirt xml file, which produces a "-net nic,macaddr=xxx,vlan=0,model=virtio" in kvm arguements.
Note: to load the virtio_net driver correctly in SLC5 DomU (guest) one need to remake an initrd image like below:
mkinitrd -f --with=virtio --with=virtio_pci --with=virtio_ring --with=virtio_blk --with=virtio_net initrd-2.6.18-164.15.1.el5.virtio.img 2.6.18-164.15.1.el5

[z] Native (Run in Dom0 - e1000)
This is the control setup, in this case all test commands are run within Dom0 (the host computer).


Server Command:
iperf -s -w 65536 -p 12345

Client Command:

[1] Link to dom0
iperf -c dom0 -w 65536 -p 12345 -t 60

[2] Link to dom0 with 4 spontaneous threads
iperf -c dom0 -w 65536 -p 12345 -t 60 -P 4

[3] Link to a remote box on the same switch
iperf -c remote -w 65536 -p 12345 -t 60 -P 4

[4] Link to a remote box on the same switch with 4 spontaneous threads
iperf -cremote -w 65536 -p 12345 -t 60 -P 4