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Hello,
I am now trying to get LinuxCNC to run stably on my fourth computer. It didn't work at all with the first two. The third and weakest one ran reasonably well but that was only a loaner.
The new one is now a Dell OptiPlex 3050 SFF with an i7. The histogram looks quite good +-30. Unfortunately, I'm having problems with the max ping times again (see attachment).

I have filmed the BIOS and network settings and you can see them here:


Are they OK or do I need to change something there?
PCW had written the following on page 1:
"If your PC has an Intel Ethernet chip make sure you disable IRQ coalescing
(man hm2_eth)"
However, my network card (enp1s0) is not listed in the networks file (see attachment). Where should I insert the entry described in man hm2_eth?
How can I determine whether the computer uses an Intel Ethernet chi at all?

Are there any other possibilities for the origin of the high ping times?
Could it also be due to the MESA card?
Best regards






 

I would disable turbo-boost in the BIOS as anything that changes the CPU clock
can cause major latencies.

The interfaces file is an alternate way to setup a network connection.
to use it, you must add the required lines to the interfaces file, something like:

       auto enp1s0
       iface enp1s0 inet static
           address 192.168.1.120/24
           hardware-irq-coalesce-rx-usecs 0


The last line only makes sense if you have a Intel Ethernet chip

One way to check for this is:

dmesg | grep -i eth

(you may need sudo dmesg | grep -i eth on some systems

or

 lspci | grep -i eth

Also check that you have ethtool installed with:

man ethtool

or the " hardware-irq-coalesce-rx-usecs 0" line will not do anything

 

Thank you for your efforts and the quick reply.
I will test it tomorrow.
I have also just ordered a network card:
Intel Gigabit CT Desktop Adapter 893647 Network Card EXPI9301CT 
Perhaps this will work better than the onboard network card.

VG Anton

Thank you again for your support.
The problem was the onboard NIC.
After I installed a PCI NIC LinuxCNC runs stable.
VG Anton

What type of Ethernet chip is used on the motherboard?

dmesg | grep -i eth
(or sudo dmesg | grep -i eth)

should show this
 

Attached is a screenshot of the output.
Realtek is the onboard NIC.
The Intel NIC works well and has a MAX ping of 0.36 after one hour. 
This command 
 hardware-irq-coalesce-rx-usecs 0
I have not yet tested this command for the new Intel NIC.

Apparently others have already had a problem with the driver!?
groups.google.com/g/linux.debian.kernel/c/HJQTXTdpBJo?pli=1

Addendum
I have just looked again at my laptop, i.e. the first device on which I installed LinuxCNC, to see which NIC driver is installed there. The r8169 RTL8168 is also listed there. I also had the problem with the laptop with the long ping time.  I have also attached a screenshot of the laptop.

I have installed the driver mentioned here
(groups.google.com/g/linux.debian.kernel/c/HJQTXTdpBJo?pli=1)
on my laptop (see attachment) and was able to reduce the max ping time from 14ms to 0.155ms for long-term ping.
This one line
# sudo apt-get install r8168-dkms
 would have saved me a lot of installation and configuration work.
Now LinuxCNC runs stable on my laptop.

Anton wrote:

I have installed the driver mentioned here
(groups.google.com/g/linux.debian.kernel/c/HJQTXTdpBJo?pli=1)
on my laptop (see attachment) and was able to reduce the max ping time from 14ms to 0.155ms for long-term ping.
This one line
# sudo apt-get install r8168-dkms
 would have saved me a lot of installation and configuration work.
Now LinuxCNC runs stable on my laptop.

I forgot how hard i tried to get Debian to acknowledge some flaws in their distro. I also raised issues with the PREEMPT_RT development team. In the end noone cares.

I think in the end the fault lies with the Linux kernel as the R8168 is poorly supported by the R8169 kernel driver and the R8168 driver is not in the kernel. This is where DKMS comes in as it allows installation of kernel modules which are recompiled if you use another kernel (most of the time)

Sorry I did not read your post earlier. This is all covered in my Debian config document. I need to add a bit on IRQ pinning which is in a sticky on the forum here
docs.google.com/document/d/1jeV_4VKzVmOI...diY/edit?usp=sharing

Hello rodw,
the document
docs.google.com/document/d/1jeV_4VKzVmOI...m1x7oiw8VcLFdiY/edit
is really great and would have helped me a lot as a beginner.
In your document there is a section "QtPyVCP, Probe Basic and EtherCAT" in which you recommend QtDragon. Do you know whether a version for lathes is also being planned?
I would like to familiarise myself with a GUI in the near future. I don't find Axis and Gmoccapy particularly appealing. My choice would now be Probe Basic Lathe, unless there is a QtDragon Lathe version.
Greetings from Marburg

I don't know about lathes. Is it mentioned in the docs? I thought one might be under way.