Asrock Q1900B-ITX
- InMyDarkestHour
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Edit: this was interesting.
Problem went away with this: disable parport in bios, boot (linux does not find parport). Reboot, set parport to manual, ECP1.7, 0x278, all irqs => works as it should.
I like your thinking
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Installed using linuxcnc-stretch-uspace-amd64-r13.iso image.
Latency is quite good, ~4000 servo, ~13000 base (2x 8G samsung M471B1G73QH0-YK0 memory modules) with kernel command line "isolcpus=2,3 acpi_irq_nobalance noirqbalance"
Using irq affinity (all to cpu0) discussed elsewhere in forum the latency is a bit better but not significantly (only a few hundred after overnight test).
Latency stays at max ~5000 servo, ~15000 base when running overnight with 6 glxgears and youtube. Additional load with samba & file transfer does not make a difference.
But when starting linuxcnc I always get "Unexpected real time delay on task 0".
uname -a:
Linux sorvi 4.9.0-8-rt-amd64 #1 SMP PREEMPT RT Debian 4.9.110-3+deb9u6 (2018-10-08) x86_64 GNU/Linux
cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-4.9.0-8-rt-amd64 root=UUID=a07de53a-6564-44d7-b7c6-86c7ea742140 ro quiet isolcpus=2,3 acpi_irq_nobalance noirqbalance
Linuxcnc output on terminal:
Unexpected realtime delay on task 0
This Message will only display once per session.
Run the Latency Test and resolve before continuing.
Unexpected realtime delay on task 0
This Message will only display once per session.
Run the Latency Test and resolve before continuing.
Shutting down and cleaning up LinuxCNC...
task: 2050 cycles, min=0.000022, max=0.011068, avg=0.009994, 0 latency excursions (> 10x expected cycle time of 0.010000s)
Note: Using POSIX realtime
Linuxcnc 2.7.14 seems not to print anything to view with dmesg. No _print.txt or _debug.txt on home directory.
Any ideas why unexpected delay happens on startup with those latency numbers ?
Or something else that can cause unexpected delay ?
Maybe I should still stay with the old rtai version if this cannot be solved... odd because of the latency should not be an issue by looking at the numbers.
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To view the linuxcnc messages, start linuxcnc from the command line (just type "linuxcnc") and you should see the same output as RTAI versions print to dmesg.
It would be interesting to run a test where a step generator output is fed to an arduino or similar, with the time between steps logged by the arduino and process into 10 second bins and then sent back through USB for analysis.
Or simply run an actual stepper motor and see if the noise sounds very regular.
It is possible that this realtime delay message is spurious, or is a one-time thing at realtime startup.
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The problem was that I wanted a newer os version and couldn't get it to work correctly. Latency test was ok but starting linuxcnc always resulted in that unexpected delay.
I solved the situation with another board (Portwell WADE 8012) wchich works well (I have 1 with mesa pci, 2 with mesa eth).
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- tommylight
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- macsddau@linuxcnc
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the 6i25 was available form eusurplus fiew weeks ago. A little expensive with vat and shiping.
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And what BASE_PERIOD became after installing this MESA 6i25 ?On an ASRock J3355B-ITX (celeron 2 cores) , I just add a MESA 6i25 to the config to solve latency problems and to remove stepping generation form the motherboard cpu. I have keep the same pinout as the parport.
the 6i25 was available form eusurplus fiew weeks ago. A little expensive with vat and shiping.
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- tommylight
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