Re: [Discuss-gnuradio] UHD Warning: Unable to set the thread priority.

[Marcus D. Leech]

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

Hi,

I'd like to ask for help when I am using GRC and the USRP source to plot the signal to a FFT.

My system is Ubuntu 11.04.    

Thanks!

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... done

-- Opening a USRP1 device...

-- Loading FPGA image: /usr/local/share/uhd/images/usrp1_fpga.rbf... done

UHD Warning:

    Unable to set the thread priority. Performance may be negatively affected.

    Please see the general application notes in the manual for instructions.

    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

OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

>>> Done

_______________________________________________

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 permissions.

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 automagically.