Latency mesage SOLVED !

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13 Oct 2019 20:35 - 13 Oct 2019 20:36 #147827 by BigJohnT
Replied by BigJohnT on topic Latency mesage
macsddau

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JT
Last edit: 13 Oct 2019 20:36 by BigJohnT.

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23 Oct 2019 15:24 #148602 by macsddau@linuxcnc
Replied by macsddau@linuxcnc on topic Latency mesage
Today I run latency test for a from 8 o'clock to 16 o'clock, watching milling videos on YouTube :silly:, reading LinuxCNC documention...
I finally obtain 69358ns max jitter.

I download StepTimingCalculator.ods file and get this result :


In INI file setup this values :
BASE_PERIOD = 70860
*_VELOCITY = 44.10

In HAL file setup this values according to Calculator file :
setp stepgen.x.steplen 1
setp stepgen.x.stepspace 1
setp stepgen.x.dirhold 2
setp stepgen.x.dirsetup 2


I get the same latency message when I run LinuxCNC.

What's wrong ?
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23 Oct 2019 15:56 #148605 by pl7i92
Replied by pl7i92 on topic Latency mesage
ok
your base period shoudt be
BASE_PERIOD = 100000
your settings in HAL per STEPGEN /AXIS
setp stepgen.0.steplen 1
setp stepgen.0.stepspace 0
setp stepgen.0.dirhold 45000
setp stepgen.0.dirsetup 45000

if you loadup your ini and hal file we can edit it

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23 Oct 2019 16:26 #148609 by macsddau@linuxcnc
Replied by macsddau@linuxcnc on topic Latency mesage

ok
your base period shoudt be
BASE_PERIOD = 100000
your settings in HAL per STEPGEN /AXIS
setp stepgen.0.steplen 1
setp stepgen.0.stepspace 0
setp stepgen.0.dirhold 45000
setp stepgen.0.dirsetup 45000

if you loadup your ini and hal file we can edit it


I don't understand why I have to use these values. I make test, compute values with the provided tool and you give me something very different.

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24 Oct 2019 18:05 #148725 by DomCa
Replied by DomCa on topic Latency mesage
Are you using rtpreemt or rtai?
With rtai you should get waayyy better latency values.

With some tuning I got all machines I tested at least under 20.000, some below 10.000 latency.

Regards
Domca
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25 Oct 2019 05:31 #148774 by macsddau@linuxcnc
Replied by macsddau@linuxcnc on topic Latency mesage

Are you using rtpreemt or rtai?

$uname -a
Linux CNC 4.9.0-11-rt-amd64 #1 SMP PREEMPT RT Debian 4.9.189-3+deb9u1 (2019-09-20) x86_64 GNU/Linux
It is installation with LinuxCNC 2.7.14 live.

With rtai you should get waayyy better latency values.

If it is a good solution, I'm very interested but I'm not familiar with Linux. I can't do any things if I don't get a very good step by step installation guide.

With some tuning I got all machines I tested at least under 20.000, some below 10.000 latency.

Have you got ASRock J3355B mini-ITX mother board running LinuxCNC ? How did you setup the BIOS ?

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30 Oct 2019 00:57 - 30 Oct 2019 00:58 #149087 by taloot
Replied by taloot on topic Latency mesage
i have same problem,, but when i do some latency test im getting about 2.0us
which is consider very good,,,, and im getting this massege ,, mybe becouse the warning designed for rtai and we are using preemptive one...

mybe its appear in all preemptive system

im using debian 64 and linuxcnc 2.8 from master
Last edit: 30 Oct 2019 00:58 by taloot.

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21 Aug 2020 17:02 #178941 by macsddau@linuxcnc
Replied by macsddau@linuxcnc on topic Latency mesage
Hi.
Since a couple of day I have make some changes in the BIOS and in GRUB.
The BIOS :
I revert all changes and then turn off every things that can disturb CPU (power save...).
The GRUB :
it is set like this
GRUB_CMDLINE_LINUX_DEFAULT="quiet isolcpus=1 idle=poll acpi_irq_nobalance noirqbalance"

Then I have run LatencyTest and LatencyHistogram with 1 YouTube video, 10 GLXGears, CATIA over Play on linux and I get this results :



This results are now pretty good for stepping.
I put the worst result in a temporary StepConf aud Copy the result into my Router Conf.

In the next days I will run LinuxCNC and see what happen with Latency Message.
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21 Aug 2020 22:21 #178961 by Himarc3D
Replied by Himarc3D on topic Latency mesage
Hi, where you found the calculator?

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22 Aug 2020 06:31 #178978 by macsddau@linuxcnc
Replied by macsddau@linuxcnc on topic Latency mesage

Hi, where you found the calculator?

Here in the documentation :
linuxcnc.org/docs/2.7/html/motion/tweaki...rs.html#_no_guessing
And the direct download link
wiki.linuxcnc.org/uploads/StepTimingCalculator.ods
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