AW: Realtime Kernel, UHD 4.0, GNURadio
Dear Community, Thank you for your suggestions and information. I will give all of it a try! I really appreciate the spirit of this mailing list! Best regards, Anton Von: Discuss-gnuradio im Auftrag von Johannes Demel Gesendet: Freitag, 6. Mai 2022 09:01 An: discuss-gnuradio@gnu.org Betreff: Re: Realtime Kernel, UHD 4.0, GNURadio Hi Anton, This guide may help you: https://kb.ettus.com/USRP_Host_Performance_Tuning_Tips_and_Tricks I usually use the CPU Governor, Thread Priority Scheduling, Adjust Network Buffers, and Adjust Ethernet MTU sections. I can run flowgraphs at 30.72MSps without hiccups. Thus, I suggest you check your host capabilities and probably more important: Check that GR is compiled and installed with `CMAKE_BUILD_TYPE=Release`. Besides, you may want to investigate which thread (and thus GR block) is the culprit. A first simple approach would be to use htop and find out which thread is close to 100% CPU load. If you change the htop Display Options to "Show custom thread names" it should be fairly simple to get a better understanding of your issue. Cheers Johannes On 05.05.22 20:52, Dobler, Anton 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 >
Re: Realtime Kernel, UHD 4.0, GNURadio
Hi Anton, This guide may help you: https://kb.ettus.com/USRP_Host_Performance_Tuning_Tips_and_Tricks I usually use the CPU Governor, Thread Priority Scheduling, Adjust Network Buffers, and Adjust Ethernet MTU sections. I can run flowgraphs at 30.72MSps without hiccups. Thus, I suggest you check your host capabilities and probably more important: Check that GR is compiled and installed with `CMAKE_BUILD_TYPE=Release`. Besides, you may want to investigate which thread (and thus GR block) is the culprit. A first simple approach would be to use htop and find out which thread is close to 100% CPU load. If you change the htop Display Options to "Show custom thread names" it should be fairly simple to get a better understanding of your issue. Cheers Johannes On 05.05.22 20:52, Dobler, Anton 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
Re: Realtime Kernel, UHD 4.0, GNURadio
On 2022-05-05 14:52, Dobler, Anton 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. There's a very very large difference between the amount of "stuff" done with a typical Gnu Radio flow-graph, and the "benchmark_rate" example. The benchmark_rate example measures the *absolute maximum* you can expect to achieve while simply consuming/emitting samples that you otherwise do nothing with. Gnu Radio, even for a "trivial" example flow-graph tends to "touch" samples a lot more than benchmark_rate would. Just the nature of the framework. 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? I have never found the real-time options to be globally optimal, but, your mileage may vary. Any help also with regards to the usage of taskset and isolcpus would be highly appreciated! Thank you in advance! BR, Anton
Re: Realtime Kernel, UHD 4.0, GNURadio
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 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 >
Realtime Kernel, UHD 4.0, GNURadio
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
