supports a certain number of VMQs, and each VMQ was assigned (affinitized) in a
round-robin manner to the logical processors available to the host, and this would
never change. The assignment of VMQs is still on a first come, first served basis in
Windows Server 2012, but the allocation of processor cores is now dynamic and fluid.
This allows the queues to be moved between logical processors based on load. By
default, all queues start on the same logical processor, the home processor, but as the
load builds on a queue, Hyper-V can move the individual queues to a different logical
processor to handle the load more efficiently. As the load drops, the queues can be
coalesced back to a smaller number of cores and potentially all back to the home
processor.
Many modern network cards support VMQ, and this is easy to check by using the
PowerShell Get-NetAdapterVmq command. In the following example, you can see that
VMQ is enabled on two of the network adapters because they are currently connected
to a Hyper-V virtual switch and each has 125 queues. If network adapters are not
connected to a virtual switch, their VMQ capabilities will not be shown.
PS C:> Get‐NetAdapterVmq `
|ft Name, InterfaceDescription,Enabled,NumberOfReceiveQueues -AutoSize
Name InterfaceDescription Enabled
NumberOfReceiveQueues
—— —————————— ———-——————————-
Name InterfaceDescription Enabled
BaseVmqProcessor MaxProcessors NumberOfReceiveQ
ueues
—— —————————— ———-——————————————-————————
NIC4 Broadcom NetXtreme Gigabit E...#4 False
0:0 16
NIC3 Broadcom NetXtreme Gigabit E...#3 False
0:0 16
NIC2 Broadcom NetXtreme Gigabit E...#2 False
0:0 16
MGMT NIC Broadcom NetXtreme Gigabit Eth... False
0:0 16 16
VM NIC Mellanox ConnectX-3 Pro Ethern... True
0:0 8 125
VM NIC 2 Mellanox ConnectX-3 Pro Ethe. . .#2 True 0:0 8 125
By default, if a virtual network adapter is configured to be VMQ enabled, no manual
action is required. Based on the availability of VMQs, a VMQ may be allocated and
used by a virtual machine. Figure 3.39 shows the Hardware Acceleration setting for a
virtual network adapter. Remember that just because a network adapter is configured
to use VMQ does not mean that it will be allocated a VMQ. It depends on whether one
is available on the network adapter when the VM is started.