Latency issue with 2.9 + bookworm + (kernel 6.1.0-13-rt-amd64)

 Hi all-I've been running 2.7 for years quite happily (and linuxcnc of one sort or another for...well, lets just say a very long time!), and I've recently installed linuxcnc 2.9 with Debian 12 (bookworm) on a 'development' machine because I'm very interested in customizing qtdragon_hd with qtdesigner etc.

But when I run this new combination on the same Gigabyte motherboard that (with 2.7) had sub-10k ns latencies, I'm now seeing 50-100k ns.  And, apparently much higher numbers less frequently.

I seem to recall someone posting that somehow re-organizing what cpu cores are in charge of what helps, but for the life of me I cannot find the thread.  I have also been sifting thorough threads related to using different kernels, but so far that has been slightly more confusing than helpful.  If anybody has any advice for me I'd greatly appreciate it!   Thanks.

Patrick

   

I would suggest to have a look at the 'official' "getting LinuxCnc" page here: linuxcnc.org/docs/2.9/html/getting-start...etting-linuxcnc.html

This should answer questions about real time performance (see section 11) as well as isolating cpu cores (section 6)... But then I strongly suggest to read the whole thing.

Thanks for the quick reply...the page you suggested is the one that I followed to install 2.9 in the first place, making it that much more embarrassing that I didn't read the parts relevant to latency etc. the first time, and didn't think to go back there later! Sheesh...if I had another brain, it would be lonely! Getting ~20k ns now, with a couple of cores isolated.

Anyway, now I can attack qtdesigner properly...

Patrick

Hi, I am having the same issue, I updated from debian 10 where I had no latency warnings and now I get warnings complaining about 1000000 ns.
Can you tell me what you've changed? I tried to isolate to cores but didn't seem to make any difference.

Thanks,
Vasi

"sudo dpkg -i linux-image-6.6.7-rt18-linuxcnc_6.6.7-1_amd64.deb "
und wenn es nicht gut ist wieder mit löschen
"sudo apt purge linux-image-6.6.7-rt18-linuxcnc "

drive.google.com/drive/folders/1HceAcPQd...u4zS9?usp=share_link

Pleaase review my how to
docs.google.com/document/d/1jeV_4VKzVmOI...diY/edit?usp=sharing

i've also had latency issues with 2.9, but it could be the pc. i went through every step i could find to speed it up. I get errors even with 1500000ns servo thread. lots of weird glitches, but could be on my end.
can't maximize Axis
positioning errors where it seems to just shift the "grid" by several hundred thousands randomly (servos, mesa serial hardware).
various other weird occurrences that i'm forgetting

Try this:
forum.linuxcnc.org/38-general-linuxcnc-q...ead-and-irq-affinity