I am using Hyper-V on a Surface Pro which runs Windows 10 (build 17134). There is a single guest VM running the latest Debian for development. This is a high spec Surface with 1TB SSD, i7 and 16GB RAM.

Network interfaces are built in:

  • "Marvell AVASTAR" wireless adapter, driver mrvlpcie8897.sys (version 15.68.9120.47, 18/10/2017).
  • "Surface Ethernet Adapter", driver msux64w10.sys (version, 27/02/2017).

Drivers are from Windows Update and the system firmware is up-to-date.

Network performance to the VM seems to be poor, especially when the host is connected to a wireless network. Please note this is internal network performance, between the host and virtual machine. Traffic is not exiting the host onto other networks.

Tests with ping

Statistics with networking disabled (no wired dock or wireless connection):

Ping statistics for
    Packets: Sent = 1000, Received = 998, Lost = 2 (0% loss)

Versus statistics connected to a local wireless network:

Ping statistics for
    Packets: Sent = 1000, Received = 958, Lost = 42 (4% loss)

Both tests were carried out sequentially under the same load, they are repeatable. The host is not stretched for performance. Two lost packets is unusual for a virtualised network, but 4% loss is remarkable. Before migrating to Hyper-V the same host ran multiple Windows & Linux VMs under VMware Workstation with no issue.

A typical sequence looks like:

Reply from bytes=32 time<1ms TTL=64
Request timed out.
Reply from bytes=32 time=1976ms TTL=64

The 2 second pause is evident as the console appears to freeze and forwarded X sessions become unresponsive. This makes interactive sessions frustrating, but not quite unusable.

Hyper-V networking information

The default virtual switch is used, which provides NAT to the internet. No changes have been made to network settings inside Hyper-V.

I have tried disabling the Virtual Machine Queue (VMQ) feature, which made no measurable difference.

Debugging inside VM

Debugging inside the VM shows that eth0 appears to connect regularly, suggesting the VM networking resets or temporarily disconnects:

Jun  7 21:35:34 vm NetworkManager[1327]: <info>  [1528403734.3473] device (eth0): carrier: link connected

Note the poor performance happens even when NetworkManager is not running.

Separately I have found that connections are reset when the host connections change, for example moving from wired to wireless or joining a VPN. In comparison to other hypervisor products this seems unusual.

Can anybody suggest further diagnostics or a potential solution for this performance?

  • Win10 version? Driver versions? – TomTom Jun 7 '18 at 14:15
  • Ok, and why do yo uconsider 4% packet loss bad on a Wireless? Do you have some reference information that shows it is not the fault of the wireless/interference? I have seen worse. – TomTom Jun 7 '18 at 14:32
  • No. This is traffic from the host to a VM. There should be practically zero loss as it’s all internal to the hypervisor. This traffic does not touch the external interfaces. – David Jun 7 '18 at 15:32
  • @David have you tried different wireless adapter? – Michal Sokolowski Jun 7 '18 at 16:39
  • I can try with a USB adapter. However, the problem is with internal traffic inside the machine. – David Jun 7 '18 at 16:41

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