Installing LinuxCNC 2.9 or Master on Linux Mint 21

royka wrote:

Since the rt patched kernels from Debian has PREEMPT_DYNAMIC=y in its config, shouldn't we use preempt=full as bootarg parameter?
I'm testing it now and got a max jitter of 30us instead of 40us, could be a coincident but I could not get it higher yet. I'm curious if others would see an improvement too.

I have tried your latest kernel 6.2 rc3 and I have managed to lower 15us.

How can I test PREEMPT_DYNAMIC=y?

"PREEMPT_DYNAMIC=y" is an option you could set before you compile which is also set at that kernel, From what I understand it means that you then need to add the boot parameter preempt=full to get the lowest latency, but I could not find a lot info about that.

The easy way to test without a permanent change is when you're in grub @ boot, press "E". Then you could add preempt=full in probably the second last line, in front of "quiet splash". Then press CTRL + X to boot. After a reboot that setting is gone.

if you type uname -v is PREEMPT_DYNAMIC still reported after you install the linux-image-rt and reboot?

 I had a feeling it showed preempt_rt on a reboot.

It showed preempt_rt indeed.
I couldn't find anywhere that it should show preempt_dynamic otherwise, but it seems logically that it should. I was searching about that config option and found that boot parameter, tried that and it showed a latency of 10us less than before with whatever I tried.
But perhaps the higher latency before that boot parameter was an incident.

tommylight post=263286 userid=17274Updated original post as this no longer works due to Python versions.
If anything changes, i will update again.

It looks to me that the python dependency is based on the system that made the deb.
I tried to make a deb on a lower python version but something failed with translations.
Linuxcnc seems to be getting harder

Python, QT, Wayland, what's next?
At one point in time, the buildbot version of LinuxCNC required Python under 3.6 and over 3.9 at the same time! I am sure i posted about that here somewhere, it is astonishing how much mess Python 3.n has made, with everything, not just with LinuxCNC.
I did waste quite some time trying to figure out how to make an appimage for LinuxCNC, from experience with plenty of apps in that format, they do work perfectly, no installation, no dependencies as everything is included, etc etc, but the tutorials online are useless and copied/pasted from the same source, information's are all about what i do not need, and none mention dependencies. Or my search-fu has failed miserably.
This would have been the best solution as it would run on almost anything, just download, make executable, run.
And since uspace version works as sim if there is no real time kernel, all would be good with the world!
Need realtime? Install kernel.
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Before anyone takes off at a tangent, no "snaps" and no "flatpak", but definitely NO SNAPS! Flatpak is bearable, somehow, maybe.