Mini PC for LinuxCNC/CPU Realtime Performance

Yes, I think people get carried away chasing the minimum. If it works without error its fine, up to about 200 usec of latency works mostly, I used 130 usec for years...

I'll hijack this thread, as my use-case is a "mini PC" NUC gen-11 i3, modest performance but which should more than adequate for LinuxCNC. Running 2.9.0 (though able to update... however same behaviour verified with another user here with standard desktop and 2.9..

With a Mesa 7i76e (other user: 7i92) - just observing HAL pins, whilst rebuilding an old Boxford 160 set-up I noticed that the HAL Write.Time pin was bubbling around 10,000-12,000 (so, 10us-12us) - which looked quite respectable given that the HM2 is scheduled on servo thread at 1ms. The hm2.read, however, was around 800,000-900,000 (verified on other user's 7i92 also), That, to my uneducated mind is getting a bit close to the limits of the 1ms servo thread. Do other people see similar performance / behaviour with Mesa cards?

I'll dig deeper and Wireshark the set-up. I should say that my particular environment the NUC wired interface is hooked to the Mesa, and I use WiFi for internet. Other user is dedicated wired interface to the machine without internet.

Probably Intel network card, so have a look here for use of ethtool to set the rx to 0
forum.linuxcnc.org/27-driver-boards/4750...i96s-a-little-jitter

Many thanks for the reply. Just SSH'd onto the machine - yes, Intel Ethernet controller. I'll wait for morning (and for the icicles to disappear) and try the recommended settings in that link, and report back.

a kernel trace also provides interesting data. when I did that on a 4 core i5, the servo thread was using about 200 usec and slept for 800 usec. Its the random incursions that take the servo-thread beyond 1000 usec that are the issue. I don't think Wireshark will show the full picture.