Latency, error finishing read, and IRQ affinity

 
Can you post the results of running this script:



to run

mv checkmask.txt checkmask
chmod +x checkmask

then

./checkmask enp2s0

Here the results from the Debian 12 system that is not working:

And here the results from the Debian 10 system that is working (same computer, just swapping HDD back and forth):

Can you try pinning the Ethernet IRQ to the last processor:

 

Use by

mv pinirq.txt pinirq
chmod +x pinirq

sudo ./pinirq enp2s0

and then try LinuxCNC again

NOTE: Look at the script before you run it as with any script
from unknown sources, especially scripts that need sudo...
 

Question, why and where did you get the info about using i915 in the kernel line?
Remove that, update grub and try again.
-
Pretty sure i read hundreds of times about i915 having to be blacklisted a few years back, so using it now seems really strange.
It was an intel chipset that lasted till i965 or i945, so that is superseded, probably 15 or more years ago.

Strange, for some reason I thought the rt_setup script had already done that.  Obviously I was mistaken as that does seem to have done the trick, have the original servo_thread value and have run multiple times through the test program. 

Really can not thank you enough and sorry that I missed that in all my other troubleshooting.

I do not know where the i915 came from, this is a vanilla install from the distro and the 2.8 was the same. Ah, I see, it is in the rt_setup script pinned to the start of this thread. I did run that in both setups trying to bring latency down.