I.3 Multiqueue on IPFE (OL/KVM)

To be enabled on the KVM flavor and glance image for IPFE instance. This improves the network throughput of a VM.

You need to update the flavor and the image to enable multiqueue. All guests using that image is created with multiqueue. By default, the combined number of queues for a VM is 1. The KVM only supports a maximum of 8 queues per VM in it is TAP devices.

Note:

The max can be increased in the VM's configuration XML but must be set to max inside the VM during runtime.

1. Enabling Multiqueue on IPFE:Increase the number of multi queues.
   Increase the number of multi queues on the VM, by default the combined number of queues for a VM is 1.

   The KVM only supports a maximum of eight queues per VM in its TAP devices.

   Note:

   The max can be increased in the VM's configuration XML but must be set to max inside the VM during runtime.
2. View the list of all the VMs:

   # virsh list --all

3. Edit the XML configuration of the VM that needs to be modified for the maximum number of combined RX and TX queues.

   # virsh edit <VM Name>

   For example: virsh edit DSRMP
4. Find the XML tag for <interface ..> .. </interface>

   Note:

   Follow this process for all the interfaces in the XML.

   The existing interface tag appears as below:
   
   

5. Modify the XML and add the following line to the interface.

   <driver name='vhost' queues='6'/>

   Here, 6 represents the number of queues and can be maximum upto 8.

   The updated tag appears as below:

   <interface type='bridge'>
       <mac address='52:54:00:bf:2f:a0'/>
       <source bridge='xsi1'/>
       <model type='virtio'/>
       <driver name='vhost' queues='6'/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
   </interface>

6. Once the XML has been modified, reboot the VM for the changes to take effect.
7. Log in to the VM using the IP or virsh console and set the number of multiqueues as required for the interfaces.

   # virsh console <VM Name>

8. Set the number of combined queues to 6:

   # ethtool -L eth2 combined 6

   Note:

   Perform this for all the interfaces (xsi1 and xsi2). The number of combined queues can vary from 1 to the value set in the guest XML in Step 5.
9. To verify, list the current number of combined queues for the interface:

   [root@DSR-Gen10-ol7 administrator]# ethtool -l eth2