Testers Needed for New RTAI Packages

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11 Oct 2019 12:43 - 11 Oct 2019 12:49 #147699 by twoflowers
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.
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Last edit: 11 Oct 2019 12:49 by twoflowers. Reason: kommafehler

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11 Oct 2019 14:55 #147706 by Bari
RTAI is only for x86.

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11 Oct 2019 16:13 #147713 by Todd Zuercher

Bari wrote: RTAI is only for x86.


Who says that?

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

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11 Oct 2019 16:24 #147714 by Bari
It's currently only working for x86 to answer twoflowers question.

Wow how did you miss this point?

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17 Oct 2019 12:55 - 17 Oct 2019 13:39 #148114 by DomCa
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
Last edit: 17 Oct 2019 13:39 by DomCa.

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17 Oct 2019 12:56 - 17 Oct 2019 12:56 #148116 by DomCa
twoflowers: Can you tell me how to get the histograms you are showing?

Thanks!
DomCa
Last edit: 17 Oct 2019 12:56 by DomCa.

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17 Oct 2019 13:42 #148117 by tommylight
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

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17 Oct 2019 16:36 - 17 Oct 2019 17:35 #148126 by DomCa
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.
Last edit: 17 Oct 2019 17:35 by DomCa.

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17 Oct 2019 17:39 #148133 by Bari

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.

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