Hardware latency tests, used PC's

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.

seuchato wrote:

You happen to know how to send a keystroke to an app in bash? Cause that's what I would love to do from time after time in my bash script.

Nope. Sorry.

There is one issue to be aware of when testing for latency on 64 bit machines with "uspace" flavour of Linuxcnc:
-Wen running latency histogram, it will set the processor at max speed and will not allow them to go down as long as the test is running,
-When running LinuxCNC on the same machine the processors will throttle up and down depending on load,
That leads to the following:
-While running LinuxCNC there is still the possibility of latency excursions despite getting good latency numbers on latency histogram,
-Setting the CPU governor to max performance should avoid this issue
-On low quality laptops setting the processor to max performance will cause them to overheat, and all laptops will run at high processor temperature making the possibility of thermal throttling very high, hence risk of latency excursions,
-LinuxCNC runs nicely on very few laptops without setting the processor to max performance and the temperatures remaining at a reasonable levels,
-This is not a big issue for PC's as most of them can handle higher temperatures easily,
-Some laptops have BIOS settings to set the processor at the lowest frequency and disable speedstep during work, this can work nicely for LinuxCNC despite low frequency.
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-Running latency tests for an hour should be enough to get a reasonable result to grant real life tests,
-Real life tests should be run for at least a day with Mesa board active, stepgens are good for this as the tests can be done without any hardware attached, i test them for two days, so 48 hours of running gcode without dropping the connection or latency errors.
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Latency errors for software stepping using base period/base thread can be easily avoided by setting the base thread to a higher value within reason, on some machines that do not require high frequency stepping i can set the base thread to 300000 and have a working machine despite bad latency,
Similarly, setting the servo thread to 2000000 can make some PC's/laptops usable, although i never use this as the risk of errors is to high.