PiAware Zero Processor Load


#1

Folks,

I’ve been running PiAware now for some months on a Pi Zero, no obvious problems.

Reading another thread suggested the Zero might not be ideal.

Now I am not sure if this is dependent on how much aircraft traffic the Pi device spots but with an ordinary indoor aerial setup and recording around 1600 aircraft daily the TOP command shows around 32% processor used by dump1090-fa which I assume is comfortable.

It is only processing data - no GUI so would have thought this is well within capabilities of the Pi.

Geffers


#2

The raspberry pi zero and zero W boards can handle any amount of ADSB only message decoding. When you have a large amount of MLAT message decoding you might start to see problems. I would say around 1400 messages/second with MLAT is the max for the raspberry pi zero.

You can find your current message rate on your sky view map. While not clicked on a plane the messages decoded per second is displayed near the top right corner of the webpage.


#3

Showing less that 200 per second.

I am around 12/15 miles from Heathrow and about 3 miles from a reasonably busy (weekends) local airport. Standard indoor aerial so maybe that is a factor.

I generally show around 25000 to 30000 mlat messages daily.

Geffers


#4

My error, MLAT is around 1500 daily, was looking at ‘others’.

Geffers


#5

You have a lot of overhead. The Raspberry pi Zero is a great way to cheaply make a flight tracking site.

I noticed you also posted on the older thread on the Raspberry Pi zero. There were some software improvements since 2016 to speed up dump1090. It would be fairly hard to overwork the processor now.

My error, MLAT is around 1500 daily, was looking at ‘others’.

The 200 message/sec is how much your actual system is working. PiAware software sends about 5-10% of the message to FlightAware which are counted in your FlightAware stats. This was done to greatly lower the amount of bandwidth needed.


#6

David,

Thank you for info. Your first comment about a lot overhead - is that referring to aircraft or Pi overheads?

I have a couple of ‘spare’ Pis that could be used but the Zero was an initial experiment and being close to Heathrow I get enough air traffic without needing to get external aerials etc.

Seems FlightAware and the Raspberry Pi project compliment each other.

Geffers


#7

The CPU overhead is more than enough for your message rates. You are around 200 messages per second and the pi zero can easily do 5x as much data decoding. This setup is good for the RPI Zero board.

The PiAware CPU usage is about 30-40% base CPU with no messages decoded and then is quite linear increases in CPU usage as you decode more messages.

The system will start to drop messages instead of decode messages once you get closer to 90%+ of CPU usage. There is going to be a warning on your FlightAware ADSB stats page if PiAware is dropping messages due to CPU.