Successfully configured with stepconf: but +Y-axis "stutters" running G-code
18 Apr 2022 13:00 #240559
by Nebur
Replied by Nebur on topic Successfully configured with stepconf: but +Y-axis "stutters" running G-code
Assuming we are still talking the same machine configuration (didn't read everything - just skimmed through the posts) - the 8GB should be plenty! I have machines running LinuxCNC happily with 2GB.
@Clung - my 2cents if you care :
Tackle the issue at hand and stop doing unrelated overly complicated stuff - just keep it really simple stupid and cut to the chase.
I would suggest:
Then, and only then - if the machine behaves and you are happy with the latency:
@Clung - my 2cents if you care :
Tackle the issue at hand and stop doing unrelated overly complicated stuff - just keep it really simple stupid and cut to the chase.
- Did you test the kernel config I suggested for preempt-rt? What was the result? Did the interrupt isolation work? Did you check by watching /proc/interrupts?
- Why 64-bit RTAI that is considered for "the more adventurous"? Why not the bulletproof 32-bit RTAI?
- Why 3 hdds? Why multiboot?
- Why running from USB?
I would suggest:
- Just disconnect everything but one hard disc that you are prepared to wipe completely
- Install the original 2.7 32bit RTAI iso (www.linuxcnc.org/iso/linuxcnc-2.7.14-wheezy.iso) on that disc (wiping it of anything that was on there! no multiboot)
- Test the latency
- Use the histogram program, ignore the other tests - the graph allows you (or us) to 'read' what's happening
- Don't waste time running the test for any length of time if the results are bad - it has no value
- Adjust the kernel params as required to improve things if required
- If you don't feel 'grub fluent' install 'grub customizer' to simplifiy playing with the kernel params
Then, and only then - if the machine behaves and you are happy with the latency:
- Update 2.7 to 2.8.x as per the instructions and setup the machine configuration
- Do whatever multi-disk / multi-boot fiddling you deem necessary
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18 Apr 2022 13:57 #240561
by Nebur
Replied by Nebur on topic Successfully configured with stepconf: but +Y-axis "stutters" running G-code
Sorry for the ambiguity - that list of questions I wrote was mostly suggestive and the "cut to the chase" and "keep it simple stupid" was meant in regards to the approach of solving the issue and not to the answering of those questions - that would be really rude
Anyway - good look!
Anyway - good look!
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18 Apr 2022 16:19 #240570
by tommylight
Replied by tommylight on topic Successfully configured with stepconf: but +Y-axis "stutters" running G-code
I am sure the 780 can be used, even with 2GB of ram, using the Wheezy ISO.
Alas, some might have memory or hdd or their corresponding controllers failing, power supply with dried capacitors, overheating processor, etc, and all those will mess up the latency, badly.
In my case all of those are easy to deal with as i owned 3 computer shops and i still do high end PC builds so i have plenty of spare parts to test with, also have access to all the local shops for anything i might need testing, i just do not have time for everything i would like to do.
Because of the above i have to refrain from just advising to get a new PC, hell it took me 4 months to get my new PC buying parts one at a time since i have everything invested in machine parts.
Despite all that, i still use some old and some very old Pc and laptops, i like using parallel port as it is very reliable.
So yes, do keep testing, Nebur makes some very good points, and no matter what the results, you have learned something, even if that sometimes means learning what does not work. Done that a lot!
How much memory is on the PC?
There are always more than one way of skinning a cat, or a PC, so if you really want to go all in, get the Debian testing non free ISO, install, change repositories to "unstable", do a full upgrade, install LinuxCNC and see how it behaves. This despite being the "beyond cutting edge" has proven good for some old PC and a laptop that was never ever usable with anything.
Alas, some might have memory or hdd or their corresponding controllers failing, power supply with dried capacitors, overheating processor, etc, and all those will mess up the latency, badly.
In my case all of those are easy to deal with as i owned 3 computer shops and i still do high end PC builds so i have plenty of spare parts to test with, also have access to all the local shops for anything i might need testing, i just do not have time for everything i would like to do.
Because of the above i have to refrain from just advising to get a new PC, hell it took me 4 months to get my new PC buying parts one at a time since i have everything invested in machine parts.
Despite all that, i still use some old and some very old Pc and laptops, i like using parallel port as it is very reliable.
So yes, do keep testing, Nebur makes some very good points, and no matter what the results, you have learned something, even if that sometimes means learning what does not work. Done that a lot!
How much memory is on the PC?
There are always more than one way of skinning a cat, or a PC, so if you really want to go all in, get the Debian testing non free ISO, install, change repositories to "unstable", do a full upgrade, install LinuxCNC and see how it behaves. This despite being the "beyond cutting edge" has proven good for some old PC and a laptop that was never ever usable with anything.
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18 Apr 2022 21:49 #240594
by andypugh
I am very close to deleting the entire forum and giving up!
Sorry, you will have to work out for yourselves whoe said what, and what was code. I have donemy best and it was not good enough.
But there was meant to be a screenshot.
Replied by andypugh on topic Successfully configured with stepconf: but +Y-axis "stutters" running G-code
Aaaargeh!!!! This editor is absolutely unusable. I have spent 20 minutes trying to get this reply formatted right, in both the source view and the normal view. It simply isn't possible, and every time you change view it moves all the tags to the end.I installed LinuxCNC from the Debian 10 .iso onto a 16GB USB thumbdrive and successfully booted into it and then patched it with the RTAI kernel following "Section 7.2" steps in LinuxCNC install.
The very next step was to try to do a calibration run, following Andy's instruction:
% sudo /usr/realtime-4.19.195-rtai-amd64/calibration/run
For reference, on a VM I get this (but obviously the numbers are terrible, it's a VM)
[/code]andypugh@buster:~/linuxcnc-dev/src$ sudo /usr/realtime-4.19.195-rtai-amd64/calibration/run password for andypugh: .runinfo is /usr/realtime-4.19.195-rtai-amd64/calibration/.runinfo No RTAI modules loaded. Running insmod on /usr/realtime-4.19.195-rtai-amd64/calibration/.runinfo... Cleaning up... RTAI successfully unloaded. Removing /tmp/runinfo... Done. andypugh@buster:~/linuxcnc-dev/src$ uname -a Linux buster 4.19.195-rtai-amd64 #5 SMP PREEMPT Sun Jul 11 19:13:27 BST 2021 x86_64 GNU/Linux andypugh@buster:~/linuxcnc-dev/src$ sudo /usr/realtime-4.19.195-rtai-amd64/testsuite/ display latency run andypugh@buster:~/linuxcnc-dev/src$ sudo /usr/realtime-4.19.195-rtai-amd64/testsuite/run .runinfo is /usr/realtime-4.19.195-rtai-amd64/testsuite/.runinfo No RTAI modules loaded. Running insmod on /usr/realtime-4.19.195-rtai-amd64/testsuite/.runinfo... RTAI testsuite and calibration tool (all data in nanoseconds) # period = 100000 (ns) # average time = 1 (s) RTH| lat min| ovl min| lat avg| lat max| ovl max| overruns RTD| -24427| -24427| 19500| 157239| 157239| 3 RTD| -24429| -24429| 19882| 170663| 170663| 4 RTD| -24472| -24472| 19432| 169168| 170663| 10 RTD| -24537| -24537| 18725| 152273| 170663| 14 RTD| -24427| -24537| 18696| 645448| 645448| 21 RTD| -24429| -24537| 19149| 185268| 645448| 27 RTD| -24419| -24537| 19021| 134501| 645448| 30 RTD| -24423| -24537| 19161| 154606| 645448| 31 RTD| -24432| -24537| 18565| 133818| 645448| 35 ^CRTD| -24432| -24537| 18565| 133818| 645448| 35 >>> S = 98.696, EXECTIME = 0.14951 Cleaning up... RTAI successfully unloaded. Removing /tmp/runinfo... Done. But on a real machine I get an error (Which I have seen before, Google gets you back here, but I don't recall the fix) [code]andypugh@rm-one:~$ sudo /usr/realtime-4.19.195-rtai-amd64/calibration/run [sudo] password for andypugh: .runinfo is /usr/realtime-4.19.195-rtai-amd64/calibration/.runinfo No RTAI modules loaded. Running insmod on /usr/realtime-4.19.195-rtai-amd64/calibration/.runinfo... Cleaning up... RTAI successfully unloaded. Removing /tmp/runinfo... Done. andypugh@rm-one:~$ sudo /usr/realtime-4.19.195-rtai-amd64/testsuite/run .runinfo is /usr/realtime-4.19.195-rtai-amd64/testsuite/.runinfo No RTAI modules loaded. Running insmod on /usr/realtime-4.19.195-rtai-amd64/testsuite/.runinfo... CANNOT FIND MAILBOX Cleaning up... RTAI successfully unloaded. Removing /tmp/runinfo... Done. The odd thing is that the second machine, if I run the normal linuxcnc "latency_test" gives me this, which is astonishingly good:
I am very close to deleting the entire forum and giving up!
Sorry, you will have to work out for yourselves whoe said what, and what was code. I have donemy best and it was not good enough.
But there was meant to be a screenshot.
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19 Apr 2022 00:00 #240611
by tommylight
Replied by tommylight on topic Successfully configured with stepconf: but +Y-axis "stutters" running G-code
That looks good so far, so it is about time you fire up the machine and make something move!
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