10G NIC performance: VFIO vs virtio: Difference between revisions

Latest revision as of 15:52, 16 May 2015

We did some experiment trying to measure network performance overhead in virtualization environment, comparing between VFIO passthrough and virtio approaches.

Test Topology

2 Intel Grantley-EP platforms (Xeon E5-2697 v3) connected by 10G link; memory 96 G.
NIC: Intel 82599ES [1]
Test Tool: iperf
OS: RHEL 7.1

Result summary

In native environment, iperf can get 9.4 Gbps throughput. Since iperf is a SW packet generator and normal process shall it be, this a reasonable number.
With VFIO passthrough, network performance is also 9.4 Gbps; i.e., we cannot observe overhead in virtualization environment with VFIO passthrough method, in context of typical SW network user application.
With virtio approach, if proper configured (details see below), network performance can also achieve 9.4 Gbps; otherwise, poor performance will be 3.6 Gbps.

Some references first

SR-IOV[2]
vt-d assignmentHow_to_assign_devices_with_VT-d_in_KVM

Here is the details about each kind of configuration.

VFIO passthrough VF (SR-IOV) to guest

Requirements

You NIC supports SR-IOV (how to check? see below)
driver (usually igb or ixgb) loaded with 'max_vfs=<num>' (better to modinfo to check accurate parameter name)
kernel modules needed: NIC driver, vfio-pci module, intel-iommu module

Check if your NIC supports SR-IOV

lspci -s <NIC_BDF> -vvv | grep -i "Single Root I/O Virtualization"

Assign the VF to a guest

Unbind from igbvf driver and Bind to VFIO driver

unbind from previous driver (take igbvf device for example)
echo <vf_BDF> > /sys/bus/pci/device/<vf_BDF>/driver/unbind

lspci -s <vf_BDF> -n //to get its number

//it will return like below

0a:13.3 0200: 8086:1520 (rev 01)

//8086 1520 is its numeric number
bind to vfio-pci driver
echo 8086 1520 > /sys/bus/pci/drivers/vfio-pci/new_id

Now you can see this device is bound to vfio-pci driver
lspci -s <vf_BDF> -k

Create guest with direct passthrough via VFIO framework
qemu-kvm -m 16G -smp 8 -net none -device vfio-pci,host=81:10.0 -drive file=/var/lib/libvirt/images/rhel7.1.img,if=virtio -nographic
'-net none' tells qemu not emulate network devices
'-device vfio-pci,host=' designate a vfio-pci device and the device's host BDF

Virtio

Requirements

virtio compiled in kernel (RHEL7.1 native kernel already have them) CONFIG_VIRTIO=m CONFIG_VIRTIO_RING=m CONFIG_VIRTIO_PCI=m CONFIG_VIRTIO_BALLOON=m CONFIG_VIRTIO_BLK=m CONFIG_VIRTIO_NET=m

Create guest with direct passthrough via VFIO framework
qemu-kvm -m 16G -smp 8 -device virtio-net-pci,netdev=net0 -netdev tap,id=net0,script=/etc/qemu-ifup -drive file=/var/lib/libvirt/images/rhel7.1.img,if=virtio –nographic

Poor performance configuration

qemu-kvm -m 16G -smp 8 -net nic,model=virtio -net tap,script=/etc/qemu-ifup -drive file=/var/lib/libvirt/images/rhel7.1.img,if=virtio –nographic
If not use '-device virtio-net-pci' option, performance will be 3.6 Gbps.

@@ Line 4: / Line 4: @@
 Intel Grantley-EP platforms (Xeon E5-2697 v3) connected by 10G link; memory 96 G.<br />
-NIC: Intel 82599ES<br />
+NIC: Intel 82599ES [http://ark.intel.com/products/41282/Intel-82599ES-10-Gigabit-Ethernet-Controller]<br />
 Test Tool: iperf <br />
 OS: RHEL 7.1 <br />
@@ Line 13: / Line 13: @@
 *With virtio approach, if proper configured (details see below), network performance can also achieve '''9.4''' Gbps; otherwise, poor performance will be '''3.6''' Gbps.
+=== Some references first ===
+SR-IOV[http://www.intel.com/content/www/us/en/network-adapters/virtualization.html]<br />
+vt-d assignment[[How_to_assign_devices_with_VT-d_in_KVM]]
 ----
@@ Line 62: / Line 65: @@
 <br />'''<nowiki>qemu-kvm -m 16G -smp 8 -net nic,model=virtio -net tap,script=/etc/qemu-ifup -drive file=/var/lib/libvirt/images/rhel7.1.img,if=virtio –nographic</nowiki>'''
 <br />If not use <nowiki>'-device virtio-net-pci'</nowiki> option, performance will be 3.6 Gbps.
+[[Category:VFIO]][[Category:Results]][[Category:Virtio]][[Category:Networking]]