Mini PC for LinuxCNC/CPU Realtime Performance

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28 Jan 2026 11:57 #342074 by giaviv
this is great, thanks for the info! what do these results indicate regarding how good this setup is for the linuxcnc application? im new to linuxcnc so the raw data doesn't mean much to me...

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28 Jan 2026 12:33 #342077 by tommylight
Replied by tommylight on topic Mini PC for LinuxCNC/CPU Realtime Performance
@NVE,
can you do the latency test with no base period and with added --show at the end as there are excursions on both periods on your screenshot, and base period is not used for Mesa boards.
Thank you.
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28 Jan 2026 12:46 #342078 by unknown
Replied by unknown on topic Mini PC for LinuxCNC/CPU Realtime Performance
With Mesa cards latency isn't such as issue as with using the Parallel port. I think the rule of thumb is under 100000ns is good for a mesa card, for about 99% of uses, cos I know someone will have an example that breaks the rule of thumb. Or my numbers may be wrong.
Unlike one forum I can think of we dont have p*$##&€ contests. ;)
If it works and does the job reliably that's the goal.
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28 Jan 2026 17:00 #342087 by OttoDidact
Replied by OttoDidact on topic Mini PC for LinuxCNC/CPU Realtime Performance
I just watched your YouTube video on reducing latency.

People were talking about isolating cores, and I think that your PC has 8 cores, not 7. Counting from zero gives you 8.

Could this be causing mischief with isolation?

Good video, that grub editor is good to know about.

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29 Jan 2026 04:35 - 29 Jan 2026 04:55 #342139 by NWE
More screenshots; for the first run I left it running for a bit without teasing it much. Then I restarted the test and let it run a bit, occationally taking a screenshot, then opening more apps.

Wow, I just noticed the load average numbers in btop. I was noticing how glxgears is not showing a lot of cpu usage, now I notice it showing up in the load average. I will go back and find out what it takes to bump that load average over 16! I will post it.

When I'm building something like LinuxCNC from source I make sure I have the build terminal and btop open so I can watch it rip! Especially on the 10yr old server with two Xeon 14 core CPU's = 56 threads.
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Last edit: 29 Jan 2026 04:55 by NWE. Reason: load average

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29 Jan 2026 05:22 - 29 Jan 2026 06:18 #342141 by NWE
Now it's bogging down. Toward the end I had to close some stuff so I could get screenshot to open. Boy, this thing is really throttling down.

Oh No! now I remember, a bit ago I was running this thing on a power tool battery+inverter , so I had changed the power limit in bios as low as it can be set! I will try one more time.
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29 Jan 2026 05:52 #342142 by NWE
I like this better. I went in the bios and changed cpu power limit back from 10W to the default 35W "performance" setting.
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29 Jan 2026 06:04 #342143 by NWE
For what it's worth, I've used $200 to $400 USD mini-pc's with way worse latency than this with ethercat and Mesa card setups and never bothered optimizing for latency. It seems to work great.

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29 Jan 2026 11:08 #342156 by rodw
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...
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