[Discuss-gnuradio] Strange uhd::device::send execution times

[Gaetano Mendola]

Hi all,
I'm observing strange execution times calling the method uhd::device::send.
The tx rate I'm using is 12.5 Mega samples per seconds and the method send
is called with 45000 samples, given the sample rate and the amount of samples
passed to this function I expect an execution time less than 0.0036 seconds per
call.
However as you can see in the attached image, the execution time is either
around 0.0026 or around 0.005 seconds. When this (still strange to me this dual
value) happens the transmissions is a successful transmission.
Some time however the executions times are much higher than those as you can
see in the second image attached (corrupted_tx.gif), when this happens I see
some "U" in the console and the transmission is corrupted. As you can see the
execution times have a singular pattern: 0.1, 0.2, 0.3, 0.4 seconds or normal
values ( < 0.0036 ).

I use the send method with  io_type equal to COMPLEX_FLOAT32 and send mode
equal to SEND_MODE_FULL_BUFF.

Is there a way to optimize the send execution time (not giving float32
but int16 for
example) ?
And why sometime the send lasts all that time ?


Regards
Gaetano Mendola

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cpp-today.blogspot.com

send_response_time.gif
Description: GIF image

corrupted_tx.gif
Description: GIF image