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Tags: 16.04   cpufreq   intel-cpu  
Link: πŸ” See Original Answer on Ask Ubuntu πŸ”—

URL: https://askubuntu.com/q/1139270
Title: Processor caps at 800Mhz
ID: /2019/04/29/Processor-caps-at-800Mhz
Created: April 29, 2019
Upload: November 24, 2022    Layout:  post
TOC: false    Navigation:  false    Copy to clipboard:  false


The following commands are used in the .gif below:

time sudo updatedb # See 8 CPUs run at 3.5 GHz. Then set 800 MHz Below
echo 800000 | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq
time sudo updatedb # See 8 CPUs run at 800 Mhz. Then set 3.5 GHz Below
echo 3500000 | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq
time sudo updatedb # Time is 3.5 seconds instead of 13.8 seconds

cpu 800 MHz demo.gif

To make a long visual short first find out maximum CPU speed before it is throttled:

rick@alien:~$ cd /sys/devices/system/cpu/cpu0/cpufreq/
───────────────────────────────────────────────────────────────────────────────────────────
rick@alien:/sys/devices/system/cpu/cpu0/cpufreq$ grep -r .
energy_performance_available_preferences:default performance balance_performance balance_power power 
scaling_min_freq:800000
scaling_available_governors:performance powersave
scaling_governor:performance
cpuinfo_max_freq:3500000
related_cpus:0
scaling_cur_freq:3218768
scaling_setspeed:<unsupported>
affected_cpus:0
scaling_max_freq:3500000
cpuinfo_transition_latency:0
energy_performance_preference:performance
scaling_driver:intel_pstate
cpuinfo_min_freq:800000

Notice the line: cpuinfo_max_freq:3500000 above. 3,500.000 MHz is my processors max speed. So to restore maximum speed I use:

echo 3500000 | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq

Most people do it one by one and some say it’s not possible to do them all at once but I’ve never had a problem doing all 8 CPUs at once. If you want to do one at a time you can use:

echo 3500000 | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
echo 3500000 | sudo tee /sys/devices/system/cpu/cpu1/cpufreq/scaling_max_freq
         ( etc., etc., etc. )
echo 3500000 | sudo tee /sys/devices/system/cpu/cpu7/cpufreq/scaling_max_freq

This will restore your CPUs to maximum speed but we still need to find out what package is setting your CPUs to 800 MHz.

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