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

[Tom Hendrick]

Josh thanks so much for the suggestion. 
I left the tb.run() alone, and used the default settings for the uhd_usrp_probe --args call for setting the frame size and number of frames.

I also just changed the buffer size for the usrp_source block by setting the following before the tb.run():

tb.uhd_usrp_source_0.set_max_output_buffer(50000000)  and I was getting overruns still.  I also tried setting it higher to
500000000 and still got overruns within about 10-20 seconds.

Do you have any other quick suggestions?  I just went back to testing on the older gnuradio libusrp 4 channel version and ubuntu 10.04 for longer durations. It gives no overruns up until about 30 minutes of running.  This is at least usable. I wonder if the buffer settings on the older setup is higher then newer one.  I'm not sure how to determine this.

Thanks, -Tom

---

From: Josh Blum <address@hidden>
To: Tom Hendrick <address@hidden>
Cc: "address@hidden" <address@hidden>
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 <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
>
>>
>> _______________________________________________ Discuss-gnuradio
>> mailing list address@hidden
>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>
>
> _______________________________________________ Discuss-gnuradio
> mailing list address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>