Linuxcnc & the Raspberry Pi (4 & 5) Official Images Only!!!

so it's perfect! if I think how much time I wasted with a nuc i3 to improve the latency without succeeding... I need it to tune up some drives that I recovered 2 years ago, now I also have the servos. if anyone knows these maybe they can give me some advice on how to use them in the best way.
drive Sanmotion rs2aa03a0al0 motor r2aa06040fxp

I haven't been on the Forum for ages but today I noticed that someone asked if I could post my RPi 5 ethernet settings on this thread.

I think they have been posted a few pages back by someone else, nevertheless the following wider context may be helpful.

As an aside, my RPi 5 and Mesa setup has worked perfectly since the ethernet issue (below) was fixed.

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The following is copied from another thread.
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I ran my RPi 5 and 7i96s overnight and completed 40 million pings with zero errors.

sudo chrt 99 ping -i .001 10.10.10.10 -c 40000000

At the same time in the background, I ran Latency Histogram and two Glxgears. I have attached photos in case anybody is interested in seeing the results.

I’m not sure what to make of the maximum ping time of just over 10 ms.

It seems that "hardware-irq-coalesce-rx-usecs 0" has fixed the issues I was having (aside from the 10 ms issue) at least on RPi 5 * GB with LinuxCNC 2.9.2.

======================================

What is this "coalesce" thing?

Interrupt coalesce settings ( access.redhat.com/documentation/en-us/re...ing_networking/index )

"By using interrupt coalescing, the system collects network packets and generates a single interrupt for multiple packets. This increases the amount of data sent to the kernel with one hardware interrupt, which reduces the interrupt load, and maximizes the throughput."

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My /etc/network/interfaces looks like this:
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source /etc/network/interfaces.d/*

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
address 10.10.10.11
hardware-irq-coalesce-rx-usecs 0

=========================== 

Looks like the Trixie issues repo got nuked, does anyone know what happened?

fenton06 wrote:

Looks like the Trixie issues repo got nuked, does anyone know what happened?

Mental health issues.

Who creates the RPi4/5 image here:

linuxcnc.org/downloads/

Not me.

tommylight wrote:

Not me.

But surely someone knows who does it.

I created the original 2.9.2 image, but have not touched it since. I don't have a pi to do anything further. I think Andy may have rebuilt later versions.
We had no choice but to build the kernel from the official pi source back then.
I think there could be better ways to do this as preempt_rt is now supported.

I tried this method (but did RIP instead):

forum.linuxcnc.org/9-installing-linuxcnc...th-preempt-rt-kernel

and the latency was horrid. The thread is from Dec 2022 thought it seems, so maybe there is a better way?

The latency isn't very good on the 2.9.8 image from the downloads page either, but not as bad as it was following the above guide. Maybe that's to be expected?

Everything just feels sluggish, and "jerky".

Is it a Pi5 or 4b? the 4b was always a bit marginal but some say the 5 is flawless for them.

You could try the Respberry way perhaps. Once you get the RT kernel sorted, just compile linuxcnc

forums.raspberrypi.com/viewtopic.php?t=396623