Installing LinuxCNC On HP T610 Thin Client

seuchato wrote:

Joco wrote:

When you run the attached script when trying to do a latency test what cpu frequency vales are you seeing?


 
Joco,
I hope you will not mind me, adding this to my scripts for latency testing?
Have to figure out on where and how it is usefull and what to protocol.
Greez
Chris

Go for it.

I have T620 plus, which script is recommend to get lower latency ?
or not ?

Ruddy
Basically, there is no script to finetune yout t620 plus. This is hard manual work with reboots and reruns of latency tests. You can use my script ( see here ). It is somewhat outdated, but it also gives some hints on improving latency. A new version will soon be available.
The current version of the script has a flaw regarding temperature measurements for AMD based CPUs, which applies the the T6x0 Thinclients unfortunately.
So, my best guess ist to wade through the very long threads here and also here . I am planning on creating a summary kind of thread with all measures taken and evaluating them for their effectiveness, as soon as my limited time allows.
Greez
chris

Just pulled mine out to have a play again. (add to swap mother boards between the T610 & T610 Plus as one of them decided to no longer boot and I wanted to use the T610 Plus)
Used the latest linuxcnc bookworm ISO, only used isolcpus=1 on the kernel command line, got rid of the cstate, irqbalance stuff and got stable latency of about 62us with just a servo thread. So this machine maybe a candidate for a Mesa connected machine. When the new PCBs arrive I'll try it via the EPP interface.

Just using isolcpus=1 with no other options kind of surprised me. Havent looked into the kernel config to see if there are any options specific to the AMD cpu used.

Cornholio
"stable latency of about 62us": seems good for servo and maybe usable for base. How did you get these results?
"When the new PCBs arrive I'll try it via the EPP interface." What PCB's are these? Interested, since I have some T620 liyng around that I's like tu use for a custom 3d printer using maybe a unoccupied BOB.
Greez
chris

Like I said just installed the Bookworm release downloaded from the linuxcnc homepage. And all I added to the command line was isolcpus=1.
Regarding the PCBs, I’ve been playing around with a Spartan 6 dev board and the Mesa hostmot2 firmware. So the PCBs just add some level shifting and connectors to the game.
I’ve also had success with a RV901t led receiver board running a modified version of the 7i90 smart serial remote firmware.
Unfortunately no Ethernet, just EPP or SPI interface. Ethernet would require a rewrite of the Ethernet section of the Mesa soft core firmware. It was a headache enough for the Smart Serial bit.
I know one of the forum members has used the Litex project to get Ethernet going, but I just wanted to stay with the Mesa sources and just make simple changes along the way.

Had a bit of an issue with the latest 2.9.2 iso.

Latency was huge compared to my last install.

My fix was to before starting the installer was to edit the kernel cmdline (press e to edit) and add after 'quiet' noefi this cause the efi stuff not to be loaded, and grub will install in "legacy" mode. During the install you will asked if you want to force EFI, say no. This will give an install that is "legacy" boot, which the T610 picks up automagically.
With a UEFI install even with isolcpus=1 latency was around 152. With a "legacy" install no isolcpus latency was around 62. This was with no base thread as it's not required.
Giving it a dry run with mesa running running on Spartan 6 dev board via EPP connected via BoB to my little desktop router thingy from Banggood I can say it performed absolutely fine.

 

cornholio
Got some T620 and T630 trailing around. Will give them I try omitting efi. Guess, I would have never come up with THIS idea So thanks a ton
greez
chris