Slow network speed in Windows HVM?

[Jarle Thorsen]

In Qubes 3.2 I have a Windows 7 HVM (with windows tools installed) connected to a NetVM with a 10Gbe network card.

The Windows VM has plenty of memory and cpu-cores allocated. I use iperf to test the bandwith to an external server using similar iperf settings in both VM's. (Trying different -w and -P settings)

In the netvm I get around 9Gbits/sec as expected, but in the Windows VM it maxes out at about 2Gbit/sec?

Is this a known limit in a Windows HVM?

[Tai...@gmx.com]

Single file network transfers aren't multi-threaded and you have the
overhead from emulated VM>VM networking.

Try assigning an SR-IOV VF to that VM if you want better speed (SR-IOV
VF is more secure than simply assigning the whole card)