USRP N210 overflows in virtual machine using GnuRadio

I am using the USRP N210 through a Debian (4.19.0-6-amd64 #1 SMP Debian 4.19.67-2+deb10u1) VM and run very quickly into processing overflow. GnuRadio-Companion is printing the letter “D” the moment one of the CPUs load is reaching 100 %. This was tested by increasing the number of taps for a low-pass filter, as shown in the picture with a sampling rate of 6.25 MHz.

I have done all instructions on How to tune an USRP, except the CPU governor. This is because I am not able to do this due to a missing driver reported by cpufreq-info. The exact output is

No or unknown cpufreq driver is active on this CPU.

The output of the lscpu command is also shown in a picture.

Has anyone an idea how I can resolve the problem? Or is GnuRadio just not fully supported for VMs?

image

I’ve tried that years ago … even with XCP virtual host … same result
I think the problem is the low performance of the visualized USB 3.0 port