On 12/27/23 13:38, Steffen Möller via Emc-developers wrote:
Gesendet: Mittwoch, 27. Dezember 2023 um 17:13 Uhr
Von: "andy pugh" <bodge...@gmail.com>
An: "EMC developers" <emc-developers@lists.sourceforge.net>
Cc: "Steffen Möller" <steffen_moel...@gmx.de>
Betreff: Re: [Emc-developers] RPi5 + Raspbian + LinuxCNC latency tests - first
impressions
On Wed, 27 Dec 2023 at 15:20, Steffen Möller via Emc-developers
<emc-developers@lists.sourceforge.net> wrote:
My RPi5 arrived over Xmas and I just fired it up, was offered to install
LinuxCNC directly from what we offer in Debian, and then ran latency tests.
Graphics (as in video but also the extra art from your X interface when
ALT-tabbing through your applications) have the most effect on the latency. I/O
from the SD does not seem to affect it too much.
The numbers you show are _awful_ though?
It doesn't look like the LinuxCNC installation has installed the
correct kernel. (I seem to recall that I had to do a fair bit of
fiddling to make it happen, it's a Pi thing)
Rebooted with
Linux version 6.1.0-rpi7-rpi-2712 (debian-ker...@lists.debian.org) (gcc-12
(Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40) #1 SMP
PREEMPT Debian 1:6.1.63-1+rpt1 (2023-11-24)
but do not see any relevant change.
That's the wrong kernel: "PREEMPT" is not enough, you need "PREEMPT_RT"
in the uname string.
This is usually the difficult part of getting systems with out-of-tree
vendor-specific kernels to work well with LinuxCNC.
--
Sebastian Kuzminsky
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