Microsoft® Windows Server® 2012 Hyper-V Dynamic Virtual Machine Queues
This blog post was originally written by Michael Schroeder.
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Introduction
Microsoft® Windows Server® 2012 introduces Dynamic Virtual Machine Queues (D-VMQ) for Hyper-V. VMQ is a hardware virtualization technology that increases the efficiency of network processing when packets are received on a Hyper-V host. This optimizes the networking performance of the host and reduces overhead as packets are delivered to virtual machines. This blog demonstrates some of the benefits of using VMQ technology with Windows Server® 2012 on your Dell™ PowerEdge™ servers.
With a Hyper-V host with dozens of VMs, which processor is responsible for handling the incoming network traffic to the VMs? Without VMQ technology and RSS, a majority of the network processing would burden CPU0 and would ultimately limit the scale of the solution. With D-VMQs, processor cores are dynamically assigned to distribute the workload. Today, with the large number of processor cores available on PowerEdge™ servers you can leverage Dynamic VMQs to get the most out of your hardware and increase the scale of your Hyper-V solutions.
“Diagram Provide by Microsoft”
VMQ Technology
Without VMQ, the Hyper-V virtual switch is responsible for routing and sorting of packets that are inbound to the VMs. This can lead to a lot of CPU processing for the virtual switch on heavily loaded Hyper-V hosts. With VMQs, this function has been moved down into the network card minimizing the burden for the virtual switch. In the silicon, queues are created for the virtual machine NICs where the routing and sorting of MAC addresses and VLAN tags are processed on the VMQ enabled NIC. Processor cores are dynamically allocated to the queues and can recruit and release processors based on the network load. This results in better processor use for adaptive network workloads.
“Diagram Provide by Microsoft”
Note: Static VMQs are offered on Windows Server® 2008 R2. Windows Server 2012® offers Dynamic Virtual Machine Queues.
VMQs and the Intel® X520 in Action
Using the Intel® X520 Dual Port 10G DA/SFP+ Server Adapter, we’ll configure virtual machine queues for our Hyper-V VMs running on the PowerEdge® R820. Intel uses the term Virtual Machine Device queues (VMDq) when referring to the hardware virtualization technology.
In my setup, the Hyper-V role is already installed, the virtual switch created and an Intel NIC port assigned. The Intel drivers have been updated to version 14.0.0 from support.dell.com.
1. Within Device Manager, we can select the network adapter port properties then under the Advanced tab we see we have performance profiles that are available to help optimize the adapter settings for a specific type of workload (Figure 1). In this case, the Intel driver detected Hyper-V and automatically designated the Virtualization Server (Hyper-V*) performance profile. Selecting a profile changes the advanced options set for the adapter.
Figure 1. NIC Performance Profiles
With the Virtualization Server profile set, we can view the Virtualization properties to see the virtual machine queues that have been assigned to processor cores (Figure 2). With VMQ technology, CPU assignment applies only to physical processor cores not logical cores. In Figure 2, we have three VMs assigned to Queue IDs 2, 3, 4. From this dialog box, you can also balance the distribution of the queues available between VMQ and SR-IOV technology depending on your Hyper-V solution needs.
Figure 2. Virtualization Properties
2. Within Hyper-V Manager, the virtual machine network adapter settings must be enabled for virtual machine queues under Network Adapter -> Hardware Acceleration.
3. To verify the VMQs allocated for my three running VMs, the following command can be run from an elevated PowerShell prompt:
Get-NetAdapterVMQQueue
Note: The R820HV1 VmFriendlyName refers to the host system.
To view the virtual machine queue properties of the Intel NIC port assigned:
Get-NetAdapterVmq | Where Enabled
From Hyper-V Manager, you can also verify that VMQ is active for a VM from the Networking tab.
Utilizing Dynamic Virtual Machine Queues (D-VMQ) in Windows Server® 2012 with a VMQ capable network adapter helps you get the most out of your PowerEdge™ systems by dynamically distributing the VM network traffic across processor cores. This is a big advantage when you have changing network demands on your Hyper-V hosts. The majority of 10 Gigabit network adapters today support the VMQ feature and can help you achieve greater scalability with your Hyper-V solutions. When shopping for network cards make sure you also check out the virtualization capabililities as well.
Additional Resources:
Dell PowerEdge 12th Generation Servers