On 2/14/25 04:05, Mike Galbraith wrote:
On Fri, 2025-02-14 at 09:31 +0100, Florian Paul Schmidt wrote:
Hi again!
On 1/14/2025 11:28 AM, Mike Galbraith wrote:
[...]
This seems rather odd, one core diddling memory is the worst case. Any
arm experts out there know why that would be?
pi5, locked at 2.4GHz:
taskset -c 3 stress -m 1 --vm-bytes 1G --vm-stride 16 --vm-keep --timeout 60s;killall cyclictest
T: 0 (23157) P:99 I:1000 C: 63421 Min: 1 Act: 12 Avg: 27 Max: 1378
T: 1 (23158) P:99 I:1500 C: 42327 Min: 1 Act: 32 Avg: 29 Max: 1734
T: 2 (23159) P:99 I:2000 C: 31744 Min: 1 Act: 18 Avg: 28 Max: 1353
T: 3 (23160) P:99 I:2500 C: 25393 Min: 1 Act: 11 Avg: 6 Max: 39
I wonder if there is still a way to save the day, i.e. use the RPI5 as a
somewhat capable RT-system by
1. making sure that the RT load does not do anything nasty - this is
mostly under the users' control since they can setup their RT load to
not do this.
I think that's the answer, don't expect miracles from cute/dinky boxen.
Beating crap out of any box is only useful for finding limits, has
nothing to do with "RT capable". A box is RT capable iff a given RT
load's hard constraints can be met on that box. Both of our stress
results show only that if you need amazing memory performance, dinky
pi5 is not for you :)
-Mike
This is all well and good Mike, you are actively researching the arm
stuff which needs some TLC.
A decade+ back up the log, I undertook to run an old Sheldon lathe with
a pi3b. Using a mesa 7i90HD spi card and a trio of 7i42TA's to isolate
the 5 volts from the 3.3 logic in the 7i90HD. Worked fairly well but
stuttered a bit from running out of data. So I switched it to an rpi4b
which does the job nicely. Then I changed the steppers to 50 volt
stepper/servo's and threw out the pid's. That where its still at today.
The servo's doubled the speeds. But that pi is still running on a 64Gig
SD card. Enter the bananapi-m5 with a builtin m2 like soldered on
memory, only 4Gb but many times faster than the micro sd card. How would
that work if the bpi-m5 were to boot and run from the m2 memory it has?
Bears investigating IMO. I am booting them from micro-sd on my 3d
printers, running them quite well. Finding how to boot from the m2, is
well hidden if possible at all. Hints appreciated. Thanks Mike.
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
