Re: [Discuss-gnuradio] LibUSRP vs LibUHD Performance on older machines

[Tom Hendrick]

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)?


Should I leave tb.run() as is, or modify the number of n_output_items in conjunction with the

  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

Thanks, -Tom

---

From: Josh Blum <address@hidden>
To: address@hidden
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

>
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