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Is there way to unlock min cpu frequency for Ubuntu 19.10 64-bit for raspberry pi?

First, this linux does't have /boot/config.txt similar to raspbian or ubuntu 18.04 from berryboot

Next, the following code has no effect

root# echo 100000 > /sys/devices/system/cpu/cpufreq/policy0/cpuinfo_min_freq

As a developer I need to test a heavy multithreaded code on a range of online cores with different CPU freq

I need to find a way to downclock CPU freq from 600 MHz down to 100 MHz (similar to raspbian)

P.S. I'm using official image from https://ubuntu.com/download/raspberry-pi

P.P.S. Also I need to switch off online cores using /sys/devices/system/cpu/cpu{1,2,3}/online files. But it does not work and kernel does not support it:

root@ubuntu /sys/devices/system/cpu/cpu3 $ echo 0 > online
-bash: echo: write error: Operation not supported
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  • But it does not work and kernel does not support it - so, you know that's not possible Commented Feb 26, 2020 at 11:02
  • I don't think the the cpu clock of the RPI4 can be changed. Where did you get that information?
    – PMF
    Commented Feb 26, 2020 at 12:43
  • @PMF, take a look at official config.txt for raspbian: raspberrypi.org/documentation/configuration/config-txt/… arm_freq_min=100 Commented Mar 1, 2020 at 21:11
  • “ As a developer I need to test a heavy multithreaded code on a range of online cores with different CPU freq” - this might buy you false security. Race condition bugs are notoriously hard to provoke on purpose. Commented Jul 5, 2023 at 6:32

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the raspberry's config.txt in ubuntu is located at /boot/firmware/config.txt, you can use it to specify range min max in the hardware, and then use cpufrequtils in ubuntu to actually set the cpu freq

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