LinuxCNC compatible industrial PC

sudo apt install lm-sensors

(Optional, but recommended): sudo sensors-detect

sensors

I did some configuration and testing on the Fitlet3.

I made changes in the BIOS, ran the script created by mozmck ( forum.linuxcnc.org/38-general-linuxcnc-q...ead-and-irq-affinity ) and did the latency test (results in the thread forum.linuxcnc.org/38-general-linuxcnc-q...ead-and-irq-affinity ). It doesn't look too good so far for the Fitlet3.

Does anyone have ideas on how to improve it because I'm all out of ideas (for now)

Just run the latency tests that come with linuxcnc. If they look ok go with it.
But I've never had much faith with the Atom platform for Linuxcnc.

I started with the latency tests, but then I found the script to run latency tests.

The best result I got with with latency-histogram --nobase was about 230000

 

I logged every change I made and the results after the change, which gives me some nice insights what happens, but I cannot get the latency any lower. 

I mentioned the "Atom platform", but I don't have enough experience with hardware to know exactly what you mean by that. I can make an educated guess, but that's basically it. 
So instead of looking for PC's of a specific brand and type, would it be better to look at platforms that work well?
 

try isolcpus=2,3

Atom is the cpu.

I've had good results with 3rd gen 4 core i5s, specifically Lenovo M73 tower, works well enough for software step generation.

Ex corporate PCs (x86/64 platforms)seem to be best bang for buck, RPi5 with a NVMe drive are quite quick, latency is usable, I've had one on the test bench communicating with a 7i92 for a few weeks with no issues. Spent a few weeks in January putting together the RPi Linuxcnc images that are for upload.
Odroid have a good range of compact x86/64 boards, I have an earlier model H3 plus that's been in for 4 or 5 years.

Asrok J series MB work well, either 4 or dual core.

I tried your suggestion, but that didn't work either.

I decided to follow the advice you guys gave me earlier and just buy and old PC (a Lenovo ThinkCentre M83 SFF). Let's hope that will yield better results.

Note that for Mesa Ethernet cards the latency test is not terribly useful.
What is much more important is network latency. Default Mesa driver settings
will drop (timeout) packets if the return data takes more than 80% of the
servo period. As long as you do not drop packets due to these timeouts, latency is
relatively unimportant/

if you have a mesa card, try this:

sudo chrt 99 ping -i .001 -q -c 60000 10.10.10.10

(this will run for 1 minute and print delay statistics)
 
Change the IP address if you use 192.168.1.121

 

Try this:
askubuntu.com/questions/1021748/set-cpu-...performance-in-18-04

It reduced latency for me.

Make sure your PC is not home to vast quantities of dust, it will block fans and airflow, and makes stuff work less well.

Thanks PCW,

I'll give that a try.