Jump in CPU utilisation


My is running raspberry for at least 6yrs without any major issues and without any changes. So I simply don’t get enough practice in trouble shooting. I do feed flightaware as well as FR24 – no change here neither. Every now and then I do run upgrade/update commands.

Early this year I have installed software providing me with performance statistics. This helped me to identify a significant increase in CPU usage. Please see attached.

I have seen posts reporting similar problems, but I wasn’t smart enough in distilling a path forward out of the discussions/replies.

While I’m picking brains here one more observation. What the h… is the RPI downloading pretty much every night? Please see also attached.

Any advice is appreciated.


The demodulator was improved.

sudo apt install nethogs

Then during one of the dowloads

sudo nethogs

Should show you what is using the bandwidth.

Thx - so feature not a bug.

[quote=“wiedehopf, post:2, topic:78355”]

sudo apt install nethogs

Then during one of the dowloads

sudo nethogs

Should show you what is using the bandwidth.

Thanks - will do.

I’m guessing this is a Pi 1?

It claims to be Raspberry Pi 2 Model B Rev 1.1

pi@piaware:~ $ cat /proc/cpuinfo
processor       : 0
model name      : ARMv7 Processor rev 5 (v7l)
... ... ...
CPU revision    : 5
... ... ...
Hardware        : BCM2835
Revision        : a21041
... ... ...
Model           : Raspberry Pi 2 Model B Rev 1.1

Piaware SD Card image ver 5.0 with following ADS-B software runing:

  • dump1090-fa
  • dump978-fa
  • piaware
  • fr24feed
  • rbfeeder
  • pfclient
  • feed-adsbx
  • opensky-network feeder
  • fa-mlat-client (for piaware)
  • mlat-client (for radarbox24)
  • mlat-client (for adsbx)
  • graphs1090 & rrdtool



Thanks abcd567!
So I should consider a rebuild from scratch

Easier and cleaner than wasting time in debugging.
Better use a SPARE microSD Card for reimaging, leaving your current install intact.

Re-imaging Made Easy


Ah OK, I misread the CPU graph as being total system CPU (which is relative to the whole system) not just the dump1090 CPU stats (which are relative to a single CPU).

It’s a little unusual to see that much of a spike on a Pi 2 - usually you’d see that more on a Pi Zero / ZeroW or Pi 1 due to the older generation ARM core on those systems - but I suspect you have the gain cranked all the way up, which tends to make the demodulator see more false-positive preamble detections, and the demodulator changes mean that there’s more work to be done per preamble detection.

6.0 will have some options to turn off more of that extra work (at the expense of slightly worse decoding) if the extra CPU is a problem.

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