On Mon, 7 Mar 2022, John Dammeyer wrote:
Date: Mon, 7 Mar 2022 00:00:41 -0800
From: John Dammeyer <jo...@autoartisans.com>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "'Enhanced Machine Controller (EMC)'" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] Pi4 with LinuxCNC and MESA 7i92H
Thanks Gene,
Didn't even think to look there. Was logged in remotely in the pi user folder
and don't have access to the /boot. (Just haven't given permission). Went to
the system and found it in /boot just as you said.
console=serial0,115200 console=tty1 root=PARTUUID=f1b66b19-02 rootfstype=ext4
elevator=deadline fsck.repair=yes isolcpus=3 idle=poll rootwait quiet splash
plymouth.ignore-serial-consoles
This site talks about
https://www.linuxtopia.org/online_books/linux_kernel/kernel_configuration/re46.html
isolcpus=1,2,3
makes no difference. The latency error still shows up.
Here's some info on the ForceTurbo
https://forum.linuxcnc.org/27-driver-boards/42413-rpi4-7i96-improving-ping-times
But this implies the stock RPi4 will _not_ run LCNC without heatsin+fan plus
boosting above stock.
John
Force Turbo or the equivalent is needed for almost any real time operation,
regardless of CPU type. Dynamic changing of CPU speeds almost always involves
very long delays (sometimes many ms) so all such schemes must be disabled
(SpeedStep, C1 states > 1, cool and quiet etc etc)
I have a RPI4 thats been running LinuxCNC for a couple of years without a fan
and without latency errors (but with a small stick-in heat sink) Without a heat
sink, the RPI4's CPU speed will always be throttled when it gets too hot.
Peter Wallace
Mesa Electronivs
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