Network quotas are ignored by libvirt when Open vSwitch is used

[Victor Stinner]

I created a flavor with quotas on the network bandwidth and created a VM with this flavor: upload limited 1 MB/sec, download limited to 500 kB/sec. The limits are ignored: copy from DevStack to the VM is faster than 13 MB/sec.

I'm using Neutron with Open vSwitch (OVS) for the network.

It looks like a regression in nova/virt/libvirt/vif.py. According to a colleague, it was maybe introduced when the OVS, LinuxBridge and HyperV classes were merged into one LibvirtGenericVIFDriver class. designer.set_vif_bandwidth_config() is only called for bridge types:

- get_config_ovs_hybrid()
- get_config_ivs_hybrid()
- network_model.VIF_TYPE_BRIDGE

Command to create the flavor and create a VM with this flavor:
---
nova flavor-create --ephemeral=1 victor_test_vif 50 256 1 1
nova flavor-key victor_test_vif set quota:vif_inbound_average=1000
nova flavor-key victor_test_vif set quota:vif_inbound_peak=1000
nova flavor-key victor_test_vif set quota:vif_outbound_peak=500
nova flavor-key victor_test_vif set quota:vif_outbound_average=500
nova boot --flavor=victor_test_vif --image=cirros-0.3.1-x86_64-uec victor_test
---

Command to start a small and fast TCP server on DevStack, uploading a file of 10 MB:
---
ip netns
# copy the qrouter-xxx name
sudo ip netns exec qrouter-128db593-a0db-40c3-84c7-e6383d40c75f bash

# following commands are executed in the qrouter namespace to reach the VM network
dd if=/dev/urandom of=random10MB bs=1024 count=10240
nc -l 0.0.0.0 12345 < random
---

Command to download the file on the VM:
---
time nc 10.0.0.1 12345 > /dev/null
---

Current result: timing smaller than 1 second (faster than 10 MB/sec)

Expected result: timing higher than 10 second (1 MB/sec or slower)

The problem is that the <bandwidth> tag is not generated in the libvirt.xml file of the VM.

I will provide a patch.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/58290

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/58290
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=497bdfec93d696c7200a71b85a0680d99ce07bb9
Submitter: Jenkins
Branch: master

commit 497bdfec93d696c7200a71b85a0680d99ce07bb9
Author: Victor Stinner <email address hidden>
Date: Fri Nov 22 17:47:05 2013 +0100

    Fix LibvirtGenericVIFDriver.get_config() for quota

    When Nova is used with Neutron and Open vSwitch, network quotas on the
    bandwidth are ignored by libvirt: the "<bandwidth>" tag is not generated in
    libvirt.xml of the virtual machine. This change fixes this issue but also for
    the network types: "bridge", "network" and "direct".

    Commands to create the flavor with download limited to 1 MB/sec and create a
    virtual machine with this flavor:
    ---
    nova flavor-create --ephemeral=1 victor_test_vif 50 256 1 1
    nova flavor-key victor_test_vif set quota:vif_inbound_average=1000
    nova boot --flavor=victor_test_vif --image=cirros-0.3.1-x86_64-uec victor_test
    ---

    Commands to upload a file to this virtual machine with SCP to check that the
    bandwidth is limited to 1 MB/sec (replace 10.0.0.3 with the IP of the virtual
    machine):
    ---
    ip netns
    sudo ip netns exec qrouter-128db593-a0db-40c3-84c7-e6383d40c75f bash

    dd if=/dev/urandom of=random10MB bs=1024 count=10240
    scp random10M cirros@10.0.3:
    ---

    Change-Id: I0f0111fc79fe90900e38df022034b208f1129088
    Closes-Bug: #1254664