Hey everyone I'm creating an application to transmit pulses for a radar system. All pulses are given a time_spec in the future. I send out all pulses in a row, each as their own burst, and then I wait for the async_metadata messages to know when they are all completed. About every 1 in 1000 sequences something causes a huge delay in the call to send. Typical timing to send pulses:
TRANSMIT time to send pulse 0 to USRP: 251us TRANSMIT time to send pulse 1 to USRP: 214us TRANSMIT time to send pulse 2 to USRP: 203us TRANSMIT time to send pulse 3 to USRP: 202us TRANSMIT time to send pulse 4 to USRP: 201us TRANSMIT time to send pulse 5 to USRP: 198us TRANSMIT time to send pulse 6 to USRP: 195us TRANSMIT time to send pulse 7 to USRP: 189us Timing when lates occur: TRANSMIT time to send pulse 0 to USRP: 46950us TRANSMIT time to send pulse 1 to USRP: 289us TRANSMIT time to send pulse 2 to USRP: 295us TRANSMIT time to send pulse 3 to USRP: 280us TRANSMIT time to send pulse 4 to USRP: 295us TRANSMIT time to send pulse 5 to USRP: 233us TRANSMIT time to send pulse 6 to USRP: 202us TRANSMIT time to send pulse 7 to USRP: 200us I understand that there is some system delay to account for when sending, which is why I do add some delay into the future for all my pulses, but these occurrences of 40-50ms delays in the call to send() seem way too long to be caused by scheduling or random kernel operations. This problem seems to happen regardless of the sample rate or number of USRPs I use. I ideally would like to run 16xN200s at a rate of 5MHz, but I still have this issue even running 1 USRP at 1MHz for testing. I've had this issue on multiple computers and multiple Linux OSes. I can attach code, however the code is very close to the implementation of tx_bursts. Anyone see anything like this when operating using timed bursts? I've tried this code on both Ubuntu and OpenSUSE operating systems. Intel(R) Core(TM) i9-7900X CPU @ 3.30GHz overclocked and ungoverned to 4.5GHz 16GB of ram overclocked to 3600MHz Intel X540-AT2 network card, 3x Netgear XS708E switches 16x USRP N200 Thanks for the help -- -Keith Kotyk
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