Re: Realtime Kernel, UHD 4.0, GNURadio

[John Sallay]

I have found that using chrt can make a big difference with USRP performance.    When using rx hardware I will run my flowgraph with chrt -f 99 python3 my_flowgraph.py.  Even when I run the ettus provided benchmarks, I have found that I will eventually drop data without realtime priority.  If you are using GRC, there is an RT setting that you can apply.  Either way, you have to have permissions set up properly to be able to elevate a process to have real time priority.

I don't know about GNURadio compatibility with realtime linux, but I have never needed it.  I've always been able to keep up using chrt and occasionally taskset.

On Thu, May 5, 2022 at 4:13 PM Dobler, Anton <anton.dobler@unibw.de> wrote:

Dear community,

I am running UHD 4.0 and GNURadio 3.10 on a Ubuntu 20.04 with a N310 as a SDR.

When I execute the benchmark_rate example with DPDK enabled, I do not see any under- or overruns even with the sampling rate set to 125 MHz, however using GNURadio - DPDK enabled here as well - I do not achieve that high sampling rate. The limit seems to be around 30MHz though. 

Do you know, apart from using taskset and isolcpus any other possibility to achieve higher sampling rates?

Would it be an option to use the realtime kernel available for Ubuntu 20.04 and is this kernel compatible with GNURadio?

Any help also with regards to the usage of taskset and isolcpus would be highly appreciated!

Thank you in advance!

BR,

Anton