Re: [Discuss-gnuradio] Flowgraph stop execution when changing sample rate of uhd_single_usrp_source

[Josh Blum]

On 12/05/2010 08:17 AM, Alexandru Csete wrote:
> Greetings,
> 
> Yesterday I updated my gnuradio/next and UHD installations to:
> UHD_0001.20101204162446.a51fb2e
> v3.3.1git-322-ge92f2cb6
> 
> I noticed that when changing USRP sample rates using
> uhd_single_usrp_source the flowgraph will suspend execution and CPU
> load drops to 0.
> The flowgraph is still alive in the sense that it is responsive to UI
> commands and sometimes even resumes execution for 5-10 seconds then
> stops again. No error message appears in the terminal.
> 
> The previous versions I have installed don't have this problem:
> UHD_0001.20101124180824.2568efd
> v3.3.1git-227-gb245c628
> 
> I also tried the combination UHD_0001.20101124180824.2568efd +
> v3.3.1git-322-ge92f2cb6 and it also has this problem which lead me to
> suspect gr-uhd rather than uhd.
> 

There was a change to the uhd single usrp source to support the tags. It
might be getting into a condition that gets stuck in the work function.

size_t total_samps = 0;
        while(total_samps + 362 < (size_t)noutput_items) {
          size_t num_samps = _dev->get_device()->recv(
              output_items, noutput_items, metadata,
              //_type, uhd::device::RECV_MODE_FULL_BUFF
              _type, uhd::device::RECV_MODE_ONE_PACKET
          );

This code looks really wrong. It will loop and the output_items pointer
doesnt increase. There is also some magic constant in there. Tom?

-Josh