performance improvement suggestions

I'm finally getting linuxcnc working (almost....). .... on a working setup.

however with a 1000000 servo loop I get this message for both the 7i76e and the 7i92h

hm2/hm2_7i92.0: error finishing read

and the GUI locks up

if I change the servo loop to 2000000 the message goes away


7i76E (plasma, mill and router) + 7i92 & 7i76 (lathe)

fanless pc i7-5500u, dual SSD (Samsung 860 Evo), 8gb ram, dual intel gigabit Ethernet ports (wg82583v)., configured for 10.10.10.10 and 10.10.10.11 for Mesa hardware.

linuxcnc is installed via 2.8 iso, upgraded to 2.9 master via buildbot.

latency jitter hovers around 32,000 and the highest I've seen is 50,000.

the fanless pc does not have an onboard WiFi, but it's provided via pcie card (intel WiFi link N 6200. I have removed it and used a usb WiFi dongle and it made no change to latency.

I have an "AC " usb dongle and also an AX200 pcie WiFi card.... but the 4.xxx RT-Preempt kernel just won't recognise them.

I suspect my problem is network port settings related....

all steedstep, hyperthreading, etc etc are disabled in the bios.

network manager is installed and wicd is removed.

I also tried editing the etc/..../ interfaces file with the sections pcw suggests adding for intel cards (didn't seem to make any difference)

should I try a newer precompiled kernel from buster backports (5.xxx) I think is available as it may better match my newer hardware?

happy to provide screenshots or try anything.

thanks for your time and directions in advance

In your ini file, did you follow this advice?

That has caused following error issues for me.

Do you have IRQ coalescing disabled?
(man hm2_eth)
This is important when using Intel Ethernet chips on the host
(and wg82583v's are Intel chips)

You can check whether you have successfully disabled IRQ coalescing with

ethtool -c DEVNAME

Where DEVNAME is the name of your real time Ethernet interface
(I suggest doing to verify this as errors in the interfaces file are simply ignored)

Also are you running both cards at once? this requires special hal file setup
using read-request to allow overlapping response times rather than adding them

Check the cooler temperature while LinuxCNC is running, it might get to hot causing the processor to throttle down.
On that note, does the error occur at the start or after a while ?
Installing some type of temp monitoring will help eliminate temperature as a cause.
Did you also disable the C states in BIOS ?

PCW wrote: Do you have IRQ coalescing disabled?
(man hm2_eth)
This is important when using Intel Ethernet chips on the host
(and wg82583v's are Intel chips)

I had to look hard to find that in the man page

There is no discussion about intel NIC's I wonder if the docs could be improved?

It applies to a number of chips but Inlel is by far the most common
chip that has a driver with this option

I guess the manual could mention that intel MACs requires this option

(Realteks driver does not have this option)

rodw wrote: In your ini file, did you follow this advice?

Code:

[AXIS_X] # The values below should be 25% larger than MAX_VELOCITY and MAX_ACCELERATION # If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger. STEPGEN_MAXVEL = 700 STEPGEN_MAXACCEL = 2000

That has caused following error issues for me.

Yes, they are +25% greater, not using Backlash comp.

______________________________________________________________________

PCW wrote: Do you have IRQ coalescing disabled?
(man hm2_eth)
This is important when using Intel Ethernet chips on the host
(and wg82583v's are Intel chips)

You can check whether you have successfully disabled IRQ coalescing with

ethtool -c DEVNAME

Where DEVNAME is the name of your real time Ethernet interface
(I suggest doing to verify this as errors in the interfaces file are simply ignored)

Also are you running both cards at once? this requires special hal file setup
using read-request to allow overlapping response times rather than adding them

Can you elaborate on the use of 2x NICs / ethernet ports please?

My plan was to use on for the 7i76E (plasma, mill, router [5xateppers]), and the 2nd for the 7i92H+7i76 (lathe [2x steppers + a step & dir servo spindle])

________________________________________________________________________________________________

tommylight wrote: Check the cooler temperature while LinuxCNC is running, it might get to hot causing the processor to throttle down.
On that note, does the error occur at the start or after a while ?
Installing some type of temp monitoring will help eliminate temperature as a cause.
Did you also disable the C states in BIOS ?

yes c-states are disabled (I've taken a load of photos, ill upload them later when I've got them all in a PDF off my phone)

Thanks very much all for the comments / suggestions and pointers.

Oh, I've monitored the temperature and the fanless PC is fine (it gets warm after a while [many hours])

The error comes up at boot time onwards, I don't believe it is temperature related / throttling related.

any merit in messing around with the cpu govenor scaling (sure something similar exists in debian) wiki.archlinux.org/index.php/CPU_frequen...#Switching_threshold

I am running debian buster, I upgraded the kernel to the backports:


The Max jitter got worse 69937

I know there have been some issues listed with 5.9 rt kernel, but I thought it as worth a shot given I'm just learning what works and what doesn't plus trying to get a bit conversant with linux and terminal etc