Testers Needed for New RTAI Packages

Ok, did some extensive testing today. i3 quadcore 3GHz, lateny < 3uS ... this is 1/10th of the best value that RT-PREEMPT could do!

Adding 20xglgears gives this result: - Still 1/5th of RT-Preempt.

Only caveat: display resolution is 1024x786 ... and I don't know why it won't go higher.

RTAI is only for x86.

Bari wrote: RTAI is only for x86.

Who says that?

It's for what ever kernel architecture you can build it for.

It's currently only working for x86 to answer twoflowers question.

Wow how did you miss this point?

Hi!

I just installed the kernel and 2.8pre linuxcnc packages on a fresh debian (amd64).
The PC is an old athlon dual core with an old 512MB Radeon card.

Without any tweeking I am getting below 10.000ns latency (copying, watching youtube and running some glxgears). For quick testing I used latency-test and as second test set the base_thread of the "axis_mm" to 10.000 and I am not getting any realtime error in linuxcnc. 5.000 is not possible on this PC.


I also tried the knwon "tricks":
isolcpus=1 acpi_irq_nobalance noirqbalance processor.max_cstate=1 intel_idle.max_cstate=0 radeon.modeset=0

However: Latency became totaly uncontrolable up to 100s of thousands.

Is the new RTAI different in this aspect?

Best regards
DomCa

twoflowers: Can you tell me how to get the histograms you are showing?

Thanks!
DomCa

That is a very good latency, like extremely good, so why are tweaking anything ?
If you have the base period set at 10.000 and no errors pop up, you can be very happy.
For the histogram, open terminal and type:
latency-histogram
If you intend to use Mesa boards, type:
latency-histogram --nobase

I know. The tuning is just out of curiosity... I can currently run my CNC at full recommended speed of 6m/min with 3200 microsteps with the official rtai linuxcnc download (and heavy tuning).

I never managed to come even near this values with the preemt version.

Will the rtai5.x and newer debian versions than currently available be an official version in the future?

With this version I had the low latencies almost instantly.

DomCa wrote:
Will the rtai5.x and newer debian versions than currently available be an official version in the future?

That is entirely up to the dev that builds the next LCNC ISO's.

This is also why we post the RTAI source and build instructions here: github.com/NTULINUX/RTAI so that you can build a working version of RTAI yourself.

@RPi & RTAI: Ok, I had an old RPi 2 some years back with a RTAI kernel (3.something). Latency was good, ~ 1/10 of the latest RT-PREEMPT kernel, so I was wonndering if anybody did get taht working on newer kernels, too.l Anyway, I have now a stock of 9 perfectly working PCs with i3, so no need to go the RPi road any more. In hindsight, I would not go the RPi road any more.