Hardware latency tests, used PC's

isent it a overkill to give a ryzon and nvidia GPU graphic system a RT CNC job
or am i lost in the history with the old parport fujitsu PC stock piling

I have around 30 Nvidia and AMD graphic cards, so i do not care much, and i have a Ryzen 3600 that i only use about once in a week or two for about 15 to 30 minutes. This now is the PC i use mostly when in shop, a measly celeron dual core at 2.7GHz with only 4GB of RAM and no add on card, and an 4 core i5 that i use after work, the rest is for testing anything i can come up with. The cards are mostly busy minnig ethereum. In total i have about 20 laptops and PC's at any given time. Worked as an IT Admin for UN and OSCE, had my own computer shops, 3 of them, so i would call that as professional deformation !
Now, before someone here goes on about me being rich, i am not, i am mostly broke because of all this. I have 5 welders that i use about twice in a year, 2 lathes one of the cnc collecting dust, and a lot, and i do mean a lot of other stuff. Now this i call a Hoarder !

Tommy

I currently have two Dell OptiPlex 980 SFF, i5 650, onboard grafics and LPT. I tested them using this guide: forum.linuxcnc.org/9-installing-linuxcnc...ick-and-easy-install (Excellent work by the way!). Kernel is 4.0.19-0-rt-amd64 I get latency, max jitter of just under 22'000 ns for base thread (25us) thread and just under 20'000 ns for servo thread (1ms) running for about 2 hours with 5 glxgears and watching Balz Müller doing freestyle on vimeo. No Isolcpus, No idle=poll, just bare boot parameters, but in bios all boot parameters set as recommended and pcspkr blacklisted (dunno, if this is really required, but I do not need it anyways). Hope this machine is good for software stepping and/or mesa ethernet control?
One unit is intended for my diy router, the other for a deckel fp2nc. I am looking to get 2 spare 980, one of these will drive a lathe (Schaublin 120VM, retrofitted). If anymore info desired, just let me know.

I could test the following machines:
IBM Z61p, 3 GB Ram, SSD, option: Dock with pciexpress and LPT
Lenovo T500, core2duo, 8 GB ram, option: Dock with pciexpress and LPT
Lenovo W510, i7, 16 GB ram, LPT would be a Exsys EX 1376 on ExpressCard slot
Fujitsu Esprimo 840 (I *think* it is a 840), i7 16 GB ram, guess no LPT possible
HP 8300 Tower, I7, 32 GB ram, on board lpt
Lenovo L540, i5, 16 GB Ram, LPT would be a Exsys EX 1376 on ExpressCard slot
Lenovo w541, i7, 32 GB Ram, LPT would be a Exsys EX 1376 on ExpressCard slot
Lenovo p50, i7, 32 GB ram, LPT would be a Exsys EX 1376 on ExpressCard slot
Lenovo T460p, i7, 32 GB ram, LPT would be a Exsys EX 1376 on ExpressCard slot

Any interest?

I think, wiki.linuxcnc.org/cgi-bin/wiki.pl?Latency-Test is a bit outdated and not as complete as it could be. How about a new page with more up to date info?

By the way: Tommy, how did you test? I guess with sata disc exchange?

Greez
chris

That is very good latency, and very usable for software stepping.
From that list, a guess would be:
Z61p might be good, needs disabling everything in BIOS,
Fujitsu might be good, most of Fujitsu's i have tested lately are very good, even laptops,
HP8300 is the preferred machine for Eth by PCW,
Lenovo's, there might be a surprise in that list, but X220 and t420s are not usable for machine control at all.
If you have access to those, please do some tests, use a USB and one of the ready made images, or an SSD with Linuxcnc installed.
You can install Linux and Linuxcnc on a PC, yank it out, put a USB to SATA adapter and plug it to any PC or Laptop and it will boot and work properly ! Make windows do that, not in your or my lifetime !
Usually i mention if it was booted from USB or installed on HDD or SSD as those do make some difference, mainly the latency will be lower when booted from USB stick or SSD than when installed to a HDD.
Thank you very much for the info.

One important thing to keep in mind during latency testing, resize the glxgears and youtube videos to full screen and back, as that will cause spikes always, especially the 4k videos on older PC's.
Command to use for latency testing in terminal: For base and servo thread:

BeagleBrainz wrote: 24hrs to compile a kernel ?

Are you using pen & paper, I thought 2 hours was slow.

LOL, again.
Was going through this topic and adding additional info, so this made me laugh again.
Thank you Beagle.
Plenty of added info to the original post and the subsequent ones, so if interested, please do have a go around again.
Thank you, all.