[Discuss-gnuradio] Getting one or more Ds after hours of running a GRC app on Ubuntu

[John Shields]

Hi,
   I am using Ubunutu 14.04 LTS with GNURadio 3.7.9.1 and have a USRP 
N200 with SBXv3. I have been using the aptly-named and highly useful 
Simple_ra though I believe this is orthogonal to the issues I am seeing.

when I run simple_ra with :

 simple_ra  --srate 2e6 --freq 848e6 --gain 37 --dcg 10000 --devid 
uhd=a,type=usrp2,addr=192.168.20.2,lo_offset=10e6,subdev=A:0 --longitude 
172.570277777 --latitude -43.519444444 --spde

the system runs along happily for several maybe even up to 20 odd hours 
but, as below, I start to see one or more Ds. In one run of 23 hours, I 
had 10 Ds and eventually a segmentation fault - not sure if it is 
coincident with issuing of the final 'D'. Sometimes the D is not 
accompanied by UHD errors

here is the terminal output from the last run:

linux; GNU C++ version 4.8.4; Boost_105400; UHD_003.010.git-156-g2d68f228

Using Volk machine: avx_64_mmx_orc
gr-osmosdr v0.1.4-72-g164a09fc (0.1.5git) gnuradio 3.7.9.1
built-in source types: file fcd rtl rtl_tcp uhd hackrf bladerf rfspace 
airspy redpitaya
-- Opening a USRP2/N-Series device...
-- Current recv frame size: 1472 bytes
-- Current send frame size: 1472 bytes
-- Detecting internal GPSDO.... Found an internal GPSDO
-- Setting references to the internal GPSDO
-- Using subdev spec 'A:0'.
-- Using LO offset of 1e+07 Hz.
WARNING: Overriding original sample rate of 1e+07 with 2e+06
-- Loaded /home/john/.uhd/cal/rx_iq_cal_v0.2_E2R10Z1XS.csv
D
UHD Error:
    Control packet attempt 0, sequence number 10594:
    RuntimeError: no control response, possible packet loss

UHD Error:
    Control packet attempt 1, sequence number 10595:
    RuntimeError: no control response, possible packet loss

UHD Error:
    Control packet attempt 2, sequence number 10596:
    RuntimeError: no control response, possible packet loss

UHD Error:
    An unexpected exception was caught in a task loop.
    The task loop will now exit, things may not work.
    RuntimeError: link dead: timeout waiting for control packet ACK
Terminated


I have a fairly powerful cpu Intel® Core™ i7-2600 CPU @ 3.40GHz × 8, 
15.6 GiB of memory and run 64-bit os and have the USRP on it's own 
subnet and NIC.
Apart from setting:
net.core.rmem_max = 50000000
net.core.wmem_max = 1048576

I have not 'tuned' any os settings. When the application is running, the 
8 cores are between 40-50% utilised.

When I restart simple_ra after the error, it runs again fine until it 
hits an issue n-hours in the future.

Any ideas of how I can narrow down the cause of this?

          Kind Regards,

                   John