UHD Warning: Unable to set the thread priority

I’d like to ask for help when I am using GRC and the USRP source to plot
signal to a FFT.
My system is Ubuntu 11.04.


linux; GNU C++ version 4.5.2; Boost_104200; UHD_003.001.002-bc87971

– Loading firmware image: /usr/local/share/uhd/images/usrp1_fw.ihx…
– Opening a USRP1 device…
– Loading FPGA image: /usr/local/share/uhd/images/usrp1_fpga.rbf…

UHD Warning:
Unable to set the thread priority. Performance may be negatively
Please see the general application notes in the manual for
EnvironmentError: OSError: error in pthread_setschedparam

UHD Warning:
The hardware does not support the requested RX sample rate:
Target sample rate: 32.000000 MSps
Actual sample rate: 16.000000 MSps

On 04/07/2011 9:54 AM, Howard wrote:

EnvironmentError: OSError: error in pthread_setschedparam

The inability to set real-time scheduling shouldn’t be a show-stopper,
in fact, I tend to not run with realtime on my systems, and
it’s just fine. But assuming that you’ve added your userid to
“usrp”, you can add the following line to /etc/security/limits.conf:

@usrp - rtprio 50

Then log out and back in, and you’ll have real-time priority

What may be an issue is that you’re running at 16Msps, which may be
higher than your CPU hardware can handle. Also, since this is
a USRP1, I think that 16Msps is only supported with 8-bit samples,
which requires that a special version of the firmware get downloaded
into the USRP1, and I’m not sure that UHD takes care of that