Hello,
I have noticed that if I run the ofdm benchmark_tx.py and benchmark_rx.py programs on both 3.6 and 3.7 versions of gnuradio, I get drastically different performance. I have been using the 3.7 live dvd to evaluate the newer version.
When running on 3.6 I can use a bandwidth of 5MHz and the receiver is able to keep up. If I use the same settings on a clean install of 3.7, after a few seconds, the buffers for multiple blocks start to overflow.
Also, on 3.6 if I use the top command to observe the CPU usage, I notice that it sits around 500-600% on an i7 machine. On the same machine with 3.7, the program only uses 200-300%.
It would appear that for some reason, in 3.7, gnuradio is not making full use of the available processors and thus is unable to keep up with the large sampling rate of 5MHz. If I drop the sampling rate to 500KHz, everything works fine on 3.7. I've used the control port programs to observe the buffers and the runtime graphs and it appears that a lot of time is being taken up by FFT filters. Did something change in 3.7 that would account for the observed differences?
Thank you in advance.
Regards,
Dirk