HM2_ETH >> iptables >> hm2−eth−rules−output

For example my times. I have approx 10m cat 7 S/ftp cable to mesa card.
3 network cards in PC. Outside, Simulator and Machine.
and it works out of the box with debian stretch. Simple config over network-manager-app in Xfce.
I would try to start with another cable..

thanks, new. cable awaited

confirmed my suspicions that something. is wrong

hmm.... no change..... cat8 patch cable (not necessary but thought it would be better quality given the higher speed rating capability) no other network devices straight from pc to 7i76e

maybe I've turned off something in the bios, but it's set to.full duplex 100

ping starts at 2.03 and second ping at 1.02/3 ms and hovers at that

hardware-irq-coalesce-rx-usecs 0 {I tried typing it in so there was no mistakes as seems to have been common on other posts}

did not work for me using the linuxcnc 2.8 iso

however installing ethtool and using within the interfaces file

post-up ethtool -C <adapter> rx-usecs 0

did work. {my intel card has a 3us rx-usecs setting as default}
Note: there was some trial and error about the location of adding the string to the interfaces file as it seemed sensitive as sometimes it was applied and sometimes not {given I have two inbuilt NIC's / ethernet ports} the best I found was to add them at the end of the file.... some posts suggested adding a sleep 5 to allow the cards and network to come up, I had success with "up-post" and putting them at the end of the interfaces file at present. I have also set speed 100, duplex full, mdix off and autoneg off..... although that does not seem to improve anything connection wise in my investigattion to lower the ping latency below ~0.200mSec latency

hardware-irq-coalesce-rx-usecs 0
was interesting as it did seem to apply (given ethtool -c <adapter> listed all values as zero)
but the ping times were high at 1.02/1.03 ms plus.

they have now dropped down to around 0.200 ISH (0.230 to about 0.175 and an occasional regular blip of 0.075 msec).... does not matter which ethernet cables I use between 300mm and 1m long (1-3 ft)

..... still investigating options....

wondering what other possible latency issues there may be to do with the sending and receiving of data packets across a wired network

{I'm going to have a look at flow control and see if it makes any other difference.

I have been through the bios 10's of time changing settings and retrying. At the moment for linuxcnc the best linuxcnc latency I have is with hyperthreading turned ON, c-states off, EIST / Speedstep off, virtualization off etc, anything ACPI / saving / throttling off, soundcard off etc.
I then used isolcpus=1,3 within grub and I get stable +/- 20 jitter with just running 5x glxgears and surfing the net (not that I intend to do that when machining...., and it rises to +/-50 jitter with youtube running and 5x glxgears

Note that disabling RT CPUs with isolcpus may in fact make your
Ethernet and LinuxCNC latency worse.

The latency test really only tests dispatch latency, overall LinuxCNC latency
actually doing things will typically be significantly worse. Watching the
.tmax values shows the actual latency

PCW wrote: Note that disabling RT CPUs with isolcpus may in fact make your
Ethernet and LinuxCNC latency worse.

The latency test really only tests dispatch latency, overall LinuxCNC latency
actually doing things will typically be significantly worse. Watching the
.tmax values shows the actual latency

Thanks.... more investigation required. (seem to have got rid of the "hm2/hm2_7176e.0: error finishing red! iter=6" once ethtool -C worked and the ping times dropped from 1.02msec to 0.200mSec).

I'll try this evening

All part of the learning process for me and I'm happy to learn.

{I've not tried it, but I was wondering if intel_pstate=disable.... etc mce=ignore_ce make any difference}