Rockpi4/hardware/cpu
ROCK Pi 4 > Hardware > CPU
RK3399 has 6 CPU core, 2 big core A72, 4 little core A53. In Linux, CPU0 to CPU3 are little core, CPU5&6 are big cores.
check cpu[0-3] supported frequency
# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies 408000 600000 816000 1008000 1200000 1416000
check cpu[4-5] supported frequency
# cat /sys/devices/system/cpu/cpu5/cpufreq/scaling_available_frequencies 408000 600000 816000 1008000 1200000 1416000 1608000 1800000
check cpu[0-3] current frequency
# cat /sys/devices/system/cpu/cpu[0123]/cpufreq/cpuinfo_cur_freq 1416000 1416000 1416000 1416000
set cpu[4-5] max frequency
# echo 1008000 > /sys/devices/system/cpu/cpu4/cpufreq/scaling_max_freq # echo 1008000 > /sys/devices/system/cpu/cpu5/cpufreq/scaling_max_freq
turn off the big cores
# echo 0 > /sys/devices/system/cpu/cpu4/online # echo 0 > /sys/devices/system/cpu/cpu5/online