{"id":45744,"date":"2024-03-05T14:53:00","date_gmt":"2024-03-05T14:53:00","guid":{"rendered":"https:\/\/ubuntuhandbook.org\/?p=45744"},"modified":"2024-05-05T13:32:56","modified_gmt":"2024-05-05T13:32:56","slug":"disable-cpu-cores-ubuntu","status":"publish","type":"post","link":"https:\/\/ubuntuhandbook.org\/index.php\/2024\/03\/disable-cpu-cores-ubuntu\/","title":{"rendered":"How to Disable CPU Cores to Save Power in Ubuntu 24.04 | 22.04"},"content":{"rendered":"

\"\"<\/a><\/p>\n

This tutorial shows how to disable certain CPU cores in Ubuntu to save power and prevent your machine from overheating.<\/p>\n

There are a few tools to manage CPU frequency and save power in Linux today. They include power-profile-daemon<\/code> (Gnome built-in power mode settings), TLP<\/a> laptop battery life saving tool, auto-cpufreq, and more.<\/p>\n

Besides limiting CPU frequency, turn off few CPU cores is another choice to cool down your PC or laptop. And, Motherboard BIOS settings page usually have a corresponding option. For choice, here’s how to do the job in Ubuntu Linux.<\/p>\n

<\/p>\n

Option 1: Single command to disable CPU core<\/h3>\n

Ubuntu and most other Linux has a \/sys\/devices\/system\/cpu\/<\/code> directory handles the CPU configurations.<\/p>\n

1. First, press Ctrl+Alt+T<\/code> on keyboard to open terminal. Then, run command to list the directory content:<\/p>\n

ls \/sys\/devices\/system\/cpu\/<\/pre>\n
In terminal output, you’ll see cpu0<\/code>, cpu1<\/code>, cpu2<\/code>, cpu3<\/code> etc sub-folders\u00a0for your CPU cores. In my case, I have 8 cores (4c\/8t). They are cpu0 ~ cpu7.<\/i><\/p>\n
\"\"<\/a><\/p>\n
2. Each sub-folder contains a ‘online<\/code>‘ config file. To disable a CPU core, just set its online<\/code> file content to 0.<\/p>\n
For example, disable cpu7 by running command:<\/p>\n
sudo sh -c \"echo 0 > \/sys\/devices\/system\/cpu\/cpu7\/online\"<\/pre>\n
By re-running last command and changing number 7<\/code>, you may continue to disable more CPU cores one by one.
\n\"\"<\/a><\/p>\n
Or, use single command to disable multiple cores:<\/p>\n
for file in $(ls \/sys\/devices\/system\/cpu\/cpu[578]*\/online); do sudo sh -c \"echo 0 > $file\"; done<\/pre>\n
The command above will disable CPU ids with number 5, 7, 8 (cpu5<\/code>, cpu7<\/code>, and cpu8<\/code> if exist).<\/i><\/p>\n
3. After making changes, verify<\/b> by either going to system ‘About’ page, or running the command below in terminal:<\/p>\n
lscpu | grep 'CPU(s)'<\/pre>\n
\"\"<\/a><\/p>\n
Option 2: Use Kernel Parameter to set how many CPU Cores to enable on startup<\/h3>\n
The changes you made in “Option 1” will be overridden on system reboot. If you want to make it work on every boot, then there’s a maxcpus<\/code> kernel parameter can do the job.<\/p>\n
1. First, press Ctrl+Alt+T<\/code> on keyboard to open terminal. When it opens, run command to edit the grub boot-loader config file:<\/p>\n
sudo gedit \/etc\/default\/grub<\/pre>\n
For Ubuntu 24.04<\/strong>, replace gedit<\/code> with gnome-text-editor<\/code>. For non-default GNOME desktop, replace gedit<\/code> with your favorite text editor, or use nano<\/code> that works in most desktops.<\/i><\/p>\n
2. When file opens, add the maxcpus=4<\/code> (change number 4 as you want.<\/i>) parameter as value to GRUB_CMDLINE_LINUX_DEFAULT<\/b>. Then, save file. For nano command line text editor, press Ctrl+S<\/b> to save, then Ctrl+X<\/b> to exit.<\/p>\n
\"\"<\/a><\/p>\n
3. Finally, apply the change by updating grub configuration (this command varies in different Linux Distros):<\/p>\n
sudo update-grub<\/pre>\n
For those who have “Grub Customizer” installed, you can also open the app and navigate to “General Settings” tab to add the kernel parameter and finally click save.<\/p>\n
\"\"<\/a><\/p>\n
In addition, the kernel parameter usually load the first 4 (or other number depends your setting) CPU cores. If you want to re-enable the left CPU cores, for example cpu7<\/code>, run command:<\/p>\n
sudo sh -c \"echo 1 > \/sys\/devices\/system\/cpu\/cpu7\/online\"<\/pre>\n
Instead of running the command above one by one with different core number, you may alternatively run single command below to re-enable all CPU cores:<\/p>\n
for file in $(ls \/sys\/devices\/system\/cpu\/cpu[0-9]*\/online); do sudo sh -c \"echo 1 > $file\"; done<\/pre>\n
Use graphical tool to disable CPU cores<\/h3>\n
For GNOME, the default desktop environment in Ubuntu and Fedora Workstation, there’s a lightweight power management extension that can do the job.<\/p>\n
It’s cpufreq which however supports GNOME up to version 44 so far (Ubuntu 23.04\/Fedora 38 and earlier). Ubuntu 24.04 is supported at the moment of writing.<\/strong><\/p>\n
\"\"<\/a><\/p>\n
Ubuntu user can first search for and install “Extension Manager<\/b>” from Ubuntu Software (App Center), then use the tool to search & install the cpufreq extension. While, Fedora and other Linux with GNOME can visit the extension web page<\/a> then use ON\/OFF toggle to install (need to install browser extension<\/i>).<\/p>\n
\"\"<\/a><\/p>\n
For non-Gnome users, there’s previously cpupower-gui<\/a> tool for Ubuntu 20.04. Sadly, it lacks development for recent Ubuntu versions support.<\/p>\n
If you know any other graphical tool to do the job, feel free to leave comment below.<\/p>","protected":false},"excerpt":{"rendered":"
This tutorial shows how to disable certain CPU cores in Ubuntu to save power and prevent your machine from overheating. There are a few tools to manage CPU frequency and save power in Linux today. They include power-profile-daemon (Gnome built-in power mode settings), TLP laptop battery life saving tool, auto-cpufreq, and more. Besides limiting CPU […]<\/p>\n","protected":false},"author":1,"featured_media":44610,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[1515],"class_list":["post-45744","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-howtos","tag-power-saving"],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/posts\/45744","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/comments?post=45744"}],"version-history":[{"count":0,"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/posts\/45744\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/media\/44610"}],"wp:attachment":[{"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/media?parent=45744"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/categories?post=45744"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ubuntuhandbook.org\/index.php\/wp-json\/wp\/v2\/tags?post=45744"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}