RTAPI error and realtime delay at EMC launch

I have a Xeon 5560 and I was having similiar issues, but disabling legacy USB support in the BIOS gave me perfectly smooth and quiet CNC drive, at speeds beyond the specs.
Have you tried to disable "legacy USB support"?
Also, you can try disabling hyperthreading.
I would definitely not do web browsing on the same machine while running a CNC mill...
You really need a dedicated machine.
Mine is also not connected to the network, for security.
You don't want to get some crazy Java script slowing down your machine while doing a cut, or someone hack into it and destroy your CNC machine.
Dangerous machinery hooked up to an internet-connected computer is asking for trouble, IMHO.
Just ask the Iranians!

The only safe computer is one that is physically disconnected...

gnagy wrote: I have a Xeon 5560 and I was having similiar issues, but disabling legacy USB support in the BIOS gave me perfectly smooth and quiet CNC drive, at speeds beyond the specs.
Have you tried to disable "legacy USB support"?
Also, you can try disabling hyperthreading.
I would definitely not do web browsing on the same machine while running a CNC mill...
You really need a dedicated machine.
Mine is also not connected to the network, for security.
You don't want to get some crazy Java script slowing down your machine while doing a cut, or someone hack into it and destroy your CNC machine.
Dangerous machinery hooked up to an internet-connected computer is asking for trouble, IMHO.
Just ask the Iranians!

The only safe computer is one that is physically disconnected...

Thanks for your answer!

Legacy USB is disabled, no effect. I can't toggle hyperthreading from the BIOS.. And actually I think this model Xeon does not even have HT?

I have had this computer (with core2duo) and CNC mill for several years now. I always surf the web and play Spotify music, or design circuit boards etc. Never had any problems.

If I don't open firefox and don't run any extra programs, latency test can run for hours and only shows under 20000 max jitter on both fields. So on a dedicated system it probably would work. But on dedidated system I wouldn't need the Xeon in the first place.

The problems is somehow related to graphics, I think. I can run very cpu-intensive programs from the shell, and jitter stays low. But just switch tabs in Firefox and boom, 1000000ns jitter.. I am running on integrated graphics which I know is a "no-no", but it did work just fine on the old CPU.

Huh,

I just tried with Radeon HD5450 graphics card which I borrowed from some other machine.

Now I have played youtube videos at 1080p, run some Windows crap with Wine, compiled linux kernel, etc.

1ms max jitter 5423ns
25us max jitter 8056ns

Woohoo!

So the internal graphics adapter was the real culprit, but somehow it needed the Xeon cpu before it got this bad? Or perhaps it still is somehow some BIOS setting, I did have to reset the BIOS settings when upgrading the CPU so some setting might not be as it was.. Hmmph.

Yeah, I noticed major slowdown for any CPU-intensive app (ray-tracing in EQUINOX-3D) when using integrated GPUs.
The biggest downside of those GPUs is that they don't have dedicated RAM, so they use the main RAM.
What a waste to do the frame-buffer scan-out, texture access etc. at 60Hz / 1080p or whatnot on the main bus, shared with the CPU!
This can really slow down memory access for the CPU.
Different CPUs have different caches and memory access patterns, different instruction ordering and so on, so real-time apps, like stepper motor step generation can easily slow down with a faster CPU.
Superscalar / out-of order instruction execution can speed up apps overall, but instruction timing will become pretty much unpredictable. Translation: more jitter.
Some CNC machine vendors swear on staying with museum-piece in-order pentiums because of this...

I am running an Atom D525MW MB with 4GB RAM, 60GB SSD, and onboard graphics. Max jitter base thread is always below 30000, but I still get the RTAPI unexpected error on a consistent basis with no apps running other than LinuxCNC/AXIS. Previous owner of this PC didn't have the problem, but I do not know what his settings were. Any suggestions as to what would get rid of this error?
Change base_period setting?
Get a dedicated graphics card?

Or is it a crap shoot?

Thanks,
Dave

Just change the base period to something bigger and test it for a while. Raise the value gradually in increments of 10.000 till you can run the machine without getting the error.