Set CPU governor to performance in 18.04

I'm trying to set the CPU governor to performance in 18.04, the problem is that it never survives reboots.

I've tried following these steps in an answer to this question How to set "Performance" instead of "Powersave" as default? but when I reboot the computer the CPU governor switches back to powersaver.

I've also tried creating a file called /etc/rc.local with the line:

cpupower frequency-set --governor performance

That also doesn't survive reboots.

How can I do this?

sudo apt-get install cpufrequtils
echo 'GOVERNOR="performance"' | sudo tee /etc/default/cpufrequtils
sudo systemctl disable ondemand

Short Answer

In /etc/rc.local put in these commands:

sleep 120
cpupower frequency-set --governor performance

1 minute after boot automatic switch to Powersave

For whatever reasons my Skylake Intel CPU always starts up in Performance mode and then switches to Powersave mode at the 1 minute mark automatically.

If you set the mode to Performance on startup it will be overridden around the 1 minute Up Time mark to Powersave mode.

In the GIF below, the 3000+ MHz CPU speed at start up appears near the top. The up time appears near the bottom. When up time hits about 1 minute you see CPU MHz drop off. :

CPU goes powersave 1 minute 2.gif

Program to monitor exact second Powersave invoked

Create this script in /usr/local/bin/watch-gov.sh:

#! /bin/bash

# NAME: watch-gov.sh
# PATH: /usr/local/bin
# DESC: Set governnor to performance and watch for change
#       Ask Ubuntu question: https://askubuntu.com/questions/1021748/set-cpu-governor-to-performance-in-18-04/1084727#1084727
# CALL: called from `/etc/rc.local`
# DATE: Created Oct 18, 2018.

echo performance | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
last_gov=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor)
Uptime=$(uptime)
echo "watch-gov.sh: Set to performance at $Uptime " > /tmp/watch-gov.log

for ((i=0; i<300; i++)) ; do
    curr_gov=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor)
    if [ $last_gov != $curr_gov ] ; then
        last_gov=$curr_gov
        Uptime=$(uptime)
        echo "watch-gov.sh: Current governor: $last_gov Uptime: $Uptime" >> \
            /tmp/watch-gov.log
    fi
    sleep 1
done

Call the script in /etc/rc.local before the exit 0 command (explained in detail below).

One minute after logging in look at the output:

$ cat /tmp/watch-gov.log
watch-gov.sh: Set to performance at  17:50:09 up 0 min,  0 users,  load average: 0.00, 0.00, 0.00 
watch-gov.sh: Current governor: powersave Uptime:  17:51:09 up 1 min,  1 user,  load average: 1.89, 0.62, 0.22

Confirmation from this answer states this 1 minute force to powersave governor is controlled by /etc/init.d/ondemand.

Sleep 120 seconds before setting Performance Mode

The simplest way to stay in Performance mode is to edit /etc/rc.local and insert these lines before the last line containing exit 0:

sleep 120 # Give CPU startup routines time to settle.
echo performance | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

Save the file and reboot.

If you insert the new lines after exit 0 it will never be executed.

To setup /etc/rc.local in 18.04 see: How to Enable /etc/rc.local with Systemd

Caveats

Your machine will probably run 10 to 15 degrees C hotter.

You may need to remove other programs that change CPU frequency if they override your Performance settings in /etc/rc.local