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

[Josh Blum]

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 <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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