Unexpected RTAI Delay Kernel 3.8

I have been getting a common warning message "RTAPI: ERROR: Unexpected realtime delay on task ...". The message occurs only at the beginning and not every time. Latency test shows the jitter around 5000 and my base period is set to 25000. I been using kernel 3.8.13, RTAI-4.0-test1, linuxcnc 2.6.0~pre on debian wheezy. It runs on intel atom d525 with isolated cpu. It worked without problem on kernel 2.6 and rtai 3.8. The main reasons for the latest configuration are video drivers for current intel motherboards. Probably the GUI is triggering this delay. Does someone have experiences with newest kernels?

Hi

As Andy says the error is only shown once anyway, often the startup triggers an error with a sudden rush of openGL calls with Axis initiating, but is never repeated.
This can be video driver or card/chip related.

If you want to reassure yourself regards latency, use the /usr/realtime/testsuite/user/latency/run program, you will soon see where the spike is and whether it is truely a one off, or something to be concerned about.

I have had problems with 3.8.13 and the new RTAI that I have not been able to nail down and which did not occur with 3.8.0 and earlier RTAI.
They all revolve around building LCNC and rtai_math, specifically unknown symbols which should be functions provided by libposemath and libm.a

I would be interested to see your kernel and rtai configs and exact RTAI version you used, to see if I can nail down where the problem has been and why yours works.

regards

rtai 4.0-test1

kernel 3.8.13



I also think it is related with opengl have to look closer which routine causes this delay because when I run glxgears still have nice latency. Even the opengl window in linuxcnc need some time to show. Old system based on squeeze worked great and without the delay. It's either the kernel part of the graphics driver or new libraries coming from debian wheezy. I also can't shutdown the computer in most cases. It is necessary to command "halrun -U" before that or you get a nice kernel panic for instance...

I would like to upload the .config files you want I've tried it tree times without success.

I would like to upload the .config files you want I've tried it tree times without success.

Thanks, easiest way is to zip them and attach the zip.

Otherwise rename them to a .txt extension and they will attach

regards

I also think it is related with opengl have to look closer which routine causes this delay because when I run glxgears still have nice latency. Even the opengl window in linuxcnc need some time to show

I have found in the past that glxgears is a good indicator of total incompatibility, but does not put enough load on to simulate Axis.
You can run glxgears and still have problems when Axis opens.
They probably do not make all the same calls and not as many of them

regards

Thanks,

However I seem to have 3 copies of the RTAI config under different names in my copy

Yes, sorry it was just a test if it's going to work I didn't expect you are so fast. Anyway the kernel is compiled for intel Atom D525 with an integrated graphics card i915 driver. It was meant to run only linuxcnc nothing else. Therefore everything what seems useless to me it's disabled.