Raspberry Pi 4 and bad latency.. SOLUTIONS?

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23 Mar 2025 08:13 #324635 by hitchhiker
Replied by hitchhiker on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?
and what does this mean? thanks

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23 Mar 2025 11:30 #324648 by tommylight
Replied by tommylight on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?
Latency excursions beyond the visible graph area.
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23 Mar 2025 21:24 #324696 by hitchhiker
Replied by hitchhiker on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?
aaaah ok... i dont undeestand because i see in the middle the big Mountain.. but left and right only 2 small stripes...

i trust what you say but dont understand in all.

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23 Mar 2025 21:37 #324698 by tommylight
Replied by tommylight on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?
When not using --show , the stripes on both sides of the graph will show that there are latency excursions beyond the visible area, meaning the latency is so big it can not be shown on the graph.
Using --show will add two more fields where the number of excursions is shown.
In short:
-stripes on both sides = bad latency that can not be shown in the graph
-no stripes = latency is only as shown in the graph.

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23 Mar 2025 21:58 #324699 by hitchhiker
Replied by hitchhiker on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?
ok and the stripes on the sides are indicator for bad latency and the middle doesnt interrest?!

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23 Mar 2025 22:31 #324705 by tommylight

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25 Mar 2025 17:39 #324899 by faeluke
Replied by faeluke on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?
So... 

What if LinuxCNC complains while starting...?

When running the latency test Tommy suggested, I saw a similar graph.

I migrated my working configuration to the PI4.. Then, I was visited by the dreaded latency complaint. 

Everything appears to work. I am running a Mesa ethernet card. What are the steps to debug and rectify the situation on a PI? 

Frank.hal attached. Do you need to see any more files?


 
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25 Mar 2025 17:42 #324900 by tommylight
Replied by tommylight on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?
Set the servo period in the ini file to 2000000 (2 million) and set the P value for each joint/axis to 500.

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25 Mar 2025 19:09 #324904 by faeluke
Replied by faeluke on topic Raspberry Pi 4 and bad latency.. SOLUTIONS?
Well, that was easy! Thank you sirl
I think I'll make some chips!
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