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cpu-frequency
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URL:
https://unix.stackexchange.com/q/463517
Title:
Get all available frequency steps
ID:
/2018/08/19/Get-all-available-frequency-steps
Created:
August 19, 2018
Edited: August 19, 2018
Upload:
September 15, 2024
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I’ve searched around and as comments say there doesn’t appear to be a table of frequencies maintained anymore.
Assuming the frequencies are scaled linearly you can approximate them by looking at the directories.
To assist in typing create this alias:
alias cpuinfo="paste <(ls *) <(cat *) | column -s $'\t' -t"
First discover the number of frequency steps
$ cd /sys/devices/system/cpu/intel_pstate
$ cpuinfo
max_perf_pct 100
min_perf_pct 22
no_turbo 0
num_pstates 28
status active
turbo_pct 33
We have 28 frequency steps determined by num_pstates.
Now look at min and max frequency MHz which can change based on Turbo Boost enabled/disabled state:
cd /sys/devices/system/cpu/cpu0/cpufreq
$ cpuinfo
affected_cpus 0
cpuinfo_max_freq 3500000
cpuinfo_min_freq 800000
cpuinfo_transition_latency 4294967295
energy_performance_available_preferences default performance balance_performance balance_power power
energy_performance_preference balance_performance
related_cpus 0
scaling_available_governors performance powersave
scaling_cur_freq 837225
scaling_driver intel_pstate
scaling_governor powersave
scaling_max_freq 3500000
scaling_min_freq 800000
scaling_setspeed <unsupported>
I may write a script later to display frequencies automatically but to do it by hand this way:
- Step Rate=(
max-min)/steps. eg (3500-800)/28=96.428 - Repeat 28 times: Rate=Last Rate+Step Rate. eg
800.00,896.42,992.856,1089.284,1185.712,1282.14…
Script to list frequencies
You can copy and paste this function into your terminal:
ApproximateFrequencies () {
NumSteps=$(cat /sys/devices/system/cpu/intel_pstate/num_pstates)
MinFreq=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq)
MaxFreq=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq)
LastFreq=$MinFreq
StepRate=$((( $MaxFreq - $MinFreq ) / $NumSteps))
for ((n=0;n<=$NumSteps;n++)); do
echo $LastFreq
LastFreq=$(( $LastFreq + $StepRate))
done
}
Then run the function using ApproximateFrequencies:
800000
896428
992856
. . .
3403556
3499984
Better still pipe through column command if you have it installed:
$ ApproximateFrequencies | column
800000 1089284 1378568 1667852 1957136 2246420 2535704 2824988 3114272 3403556
896428 1185712 1474996 1764280 2053564 2342848 2632132 2921416 3210700 3499984
992856 1282140 1571424 1860708 2149992 2439276 2728560 3017844 3307128