Foundational questions about my setup

rodw wrote:

Try
sudo apt install r8168-dkms
You need the linux headers for your RT kernel installed

More info here 
docs.google.com/document/d/1jeV_4VKzVmOI...diY/edit?usp=sharing
 

Wonderful hint, thank you.

PCW wrote:

To get an idea of where you are is to run the command:

halcmd show param *.tmax

When LinuxCNC is running.

These times will be in CPU clocks on X86 CPUs

Also the ping times (pinging the Mesa card) will help
 

Thank you very much PCW, you've been very helpful with this machine in private emails in the past as well.

Small note for anyone in the future, the dkms driver actually made my latency worse and lcnc unusable. I guess I should always test.

Kernel 6.6.13 In-tree driver:

linuxcnc@linuxcnc:~$ sudo taskset -c 3 chrt 99 ping 192.168.1.121
PING 192.168.1.121 (192.168.1.121) 56(84) bytes of data.
64 bytes from 192.168.1.121: icmp_seq=1 ttl=64 time=0.170 ms
64 bytes from 192.168.1.121: icmp_seq=2 ttl=64 time=0.103 ms
64 bytes from 192.168.1.121: icmp_seq=3 ttl=64 time=0.103 ms
64 bytes from 192.168.1.121: icmp_seq=4 ttl=64 time=0.103 ms
64 bytes from 192.168.1.121: icmp_seq=5 ttl=64 time=0.105 ms
64 bytes from 192.168.1.121: icmp_seq=6 ttl=64 time=0.101 ms
64 bytes from 192.168.1.121: icmp_seq=7 ttl=64 time=0.101 ms

linuxcnc@linuxcnc:~$ halcmd show param hm2*.tmax
Parameters:
Owner   Type  Dir         Value  Name
    45  s32   RW              0  hm2_7i95.0.read-request.tmax
    45  s32   RW         479510  hm2_7i95.0.read.tmax
    45  s32   RW          93556  hm2_7i95.0.write.tmax

DKMS Realtek Driver 8.053:

linuxcnc@linuxcnc:~$ sudo taskset -c 3 chrt 99 ping 192.168.1.121
PING 192.168.1.121 (192.168.1.121) 56(84) bytes of data.
64 bytes from 192.168.1.121: icmp_seq=1 ttl=64 time=1.17 ms
64 bytes from 192.168.1.121: icmp_seq=2 ttl=64 time=1.18 ms
64 bytes from 192.168.1.121: icmp_seq=3 ttl=64 time=1.19 ms
64 bytes from 192.168.1.121: icmp_seq=4 ttl=64 time=1.18 ms
64 bytes from 192.168.1.121: icmp_seq=5 ttl=64 time=1.18 ms

linuxcnc@linuxcnc:~$ halcmd show param hm2*.tmax
Parameters:
Owner   Type  Dir         Value  Name
    45  s32   RW              0  hm2_7i95.0.read-request.tmax
    45  s32   RW        1290884  hm2_7i95.0.read.tmax
    45  s32   RW          85734  hm2_7i95.0.write.tmax

And I got a joint following error and a read error almost instantly from hostmot2.

The listed read.tmax (479510) is not enough to cause a problem (~300 usec),
but if you get read errors its means you have had a burst of timeout errors
with read  times > 800 usec. (Tmax > 1200000 with a 1.5 GHz CPU)

I would first verify that you have the usual suspects eliminated by
disabling all power management in the BIOS (Turbo modes, EIST, C states > C1,
PCIE and network power management) and disable any Intel spyware like AMT
and hyperthreading if applicable.

If this does not help, the next step is to pin the Ethernet IRQ to the last processor (3)
and set isolcpus=3 in grub

I had similar issues with a small PC with Realtek NICs. In my case it was an early board revision and a bios update fixed it. Messing with the NIC drivers and everything else wasn't really helping. Can't say that a bios update would help in your case but you should definately see if something is available or see what bios settings are possible in regards to the NICs.

hachi wrote:

Small note for anyone in the future, the dkms driver actually made my latency worse and lcnc unusable. I guess I should always test.
following error and a read error almost instantly from hostmot2.

Sorry about that. Very odd it did not work. Its been a while since i tried it.