L-1017e.A3 i.MX 8M Plus BSP Manual
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userspace
allows the user or userspace program running as root to set a specific frequency (e.g. to 1600000).
Type:
In order to ask for the current governor, type:
target$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
You will normally get:
ondemand
Switching over to another governor (e.g.
userspace
) is done with:
target$ echo userspace > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
Now you can set the speed
target$ echo
1600000
> /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
For more detailed information about the governors, refer to the
Linux
kernel documentation in
linux/
Documentation/cpu-freq/governors.txt.
CPU Core Management
The i.MX 8M plus SoC can have multiple processor cores on the die. The i.MX 8M Plus, for example, has 4 ARM Cores
which can be turned on and off individually at runtime.
To see all available cores in the system, execute:
target$ ls /sys/devices/system/cpu -
1
This will show, for example:
cpu0 cpu1 cpu2 cpu3 cpufreq
[...]
Here the system has four processor cores. By default, all available cores in the system are enabled to get maximum
performance.
To switch off a single-core, execute:
target$ echo
0
> /sys/devices/system/cpu/cpu3/online
As confirmation, you will see:
