On 03/08/2013 02:44 PM, Tom Hendrick wrote: > Hi Josh, > > Would you happen to suggest any more setting changes I could try before just > deciding I need to depend on the older libusrp/gnuradio for recording 4 > channels to disk from a USRP?
On this particular machine, are you able to sustain one channel at 8Msps but not 4 channels at 2Msps? That might indicate that there isnt enough headroom for the deinterleaving. The old driver just output interleaved data, and you would deinterleave samples in a separate block. -josh > Thanks, - Tom > > > > > > ________________________________ > From: Josh Blum <j...@ettus.com> > To: Tom Hendrick <sdtom...@yahoo.com> > Cc: "discuss-gnuradio@gnu.org" <discuss-gnuradio@gnu.org> > Sent: Saturday, March 2, 2013 9:18 AM > Subject: Re: [Discuss-gnuradio] LibUSRP vs LibUHD Performance on older > machines > > > > On 03/01/2013 05:16 PM, Tom Hendrick wrote: >> Josh, >> >> Thank you so much for the suggestion. I will try this. I have 4GB of >> ram and a 4GB swapfile size. Do you recommend any particular setting >> for set_max_output_buffer(long max_output_buffer)? >> >> > > Make it 10s of megabytes, see if it helps. > >> Should I leave tb.run() as is, or modify the number of n_output_items >> in conjunction with the > > I think that part of the API is deprecated (the argument to run). There > is a similar call on top block, but Im recommending just the usrp source > block. > >> >> void set_max_output_buffer(long max_output_buffer)? >> >> >> Also, do you recommend any particular settings using uhd_usrp_probe >> --args="serial=123456, recv_frame_size=XXXX,num_recv_frames=XXXX", >> send_frame_size=XXXX,send_recv_frames=XXX" >> >> >> or should I leave it default? The custom 4 channel usrp block in the >> older gnuradio version had the fusb_block and fusb_nblocks both set >> to 512*32 >> > > Go with the default while trying the above. > > -josh > >> Thanks, -Tom >> >> >> >> >> ________________________________ From: Josh Blum <j...@ettus.com> To: >> discuss-gnuradio@gnu.org Sent: Friday, March 1, 2013 2:55 PM Subject: >> Re: [Discuss-gnuradio] LibUSRP vs LibUHD Performance on older >> machines >> >> >> >> On 03/01/2013 04:51 PM, Tom Hendrick wrote: >>> Hello all, >>> >>> I've had trouble making a 4 channel USRP samples at 1Ms/s write to >>> file at 500 kS/s with ubuntu 12.04 and libuhd. I am getting >>> several overruns and I had tried adjusting some of the parameters >>> using usrd_probe_devices but with no success. I have a laptop with >>> a duo core centrino processor which should be enough. >>> >>> I've made this 4 channel work successfully with the same exact >>> laptop and with ubuntu 10.04 and the older version of gnuradio that >>> uses libusrp. I get no underruns at all even for an entire hour of >>> writing to file. >>> >>> >>> Has anyone else experienced performance differences between libusrp >>> and libuhd? I just want to make sure it isn't a configuration >>> problem or something I'm doing wrong causing the overruns. If its >>> likely an issue with libuhd, I guess I will just keep a backup of >>> ubuntu 10.04 and gnuradio libusrp version installation files and >>> leave my dual boot setup intact. >>> >>> Thank you very much, - Tom >>> >>> >> >> You might try setting a very large output buffer on the usrp source >> block. I heard this helps (you should be able to call this in python >> after the block constructs): >> >> /*! * \brief Sets max buffer size on all output ports. */ void >> set_max_output_buffer(long max_output_buffer) >> >> -josh >> >>> >>> _______________________________________________ Discuss-gnuradio >>> mailing list Discuss-gnuradio@gnu.org >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >> >> _______________________________________________ Discuss-gnuradio >> mailing list Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
