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How to resolve Slow Hyper-V Guest Network Performance Microsoft Server 2012 R2 with Dell Server using Broadcom NetXtreme 1Gb NICs


ENVIRONMENT

My Hyper-V hosts are Dell PowerEdge R520, utilizing Broadcom NetXtreme 1Gb NICs and running Server 2008R2 SP2. Firmware/drivers all up to date. The issue has only ever existed on the guest VMs, never the host nor any other baremetal box.


RESOLUTION

There's this little thing called Virtual Machine Queues. In short, it increases overall throughput for VMs by offloading virtual network processing to the physical adapter. Read more here.


Prior to stumbling across that article, I had actually stumbled upon a resolution that basically solves the issue by simply disabling VMQ on the physical adapters assigned to the VMs. But I started reading about VMQ and I wanted it!
So I then found the above article and realized the problem:


Broadcom has VMQ enabled by default, however, there is a registry value that needs to be added first for VMQ to function properly. Without the registry value, you get the problem of slow network performance.


STEPS

Since Broadcom has VMQ enabled by default, I disable it in the configuration properties of all my physical adapters assigned to my guests, in the advanced tab. Intel NIC owners need not do this step, as Intel has it disabled by default.

  1. Since Broadcom has VMQ enabled by default, I disable it in the configuration properties of all my physical adapters assigned to my guests, in the advanced tab. Intel NIC owners need not do this step, as Intel has it disabled by default.

  2. On my Hyper-V host, I open Regedit and drill down to HKLM\SYSTEM\CurrentControlSet\Services\VMSMP\Parameters

  3. I then add to Parameters a DWORD value and name it BelowTenGigVmqEnabled (since I have a 1Gb adapter. 10Gb owners need TenGigVmqEnabled) and give it a value of 1.

  4. Finally, I go back to the physical adapters and enable Virtual Machine Queues.

Instantaneously, network performance issues are solved and my pings are all <1ms. This also actually sped up the OS in my VMs and they are no longer sluggish.


Please leave a comment if this helped you! 



Article ID: 122, Created On: 7/11/2016, Modified: 7/11/2016

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