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title Managing Linux Kernels & Sched-ext framework with the CachyOS Kernel Manager
description The CachyOS Kernel Manager is a powerful tool for managing kernels, allowing users to easily install or build custom kernels with ease.
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import ImageComponent from '~/components/image-component.astro';

Installing a Kernel from a Repository

:::warning[Important: Reboot After System Update]

Before using Kernel Manager to switch or install kernels, make sure to reboot your system if you recently performed a system update.

Why?

  • Running kernel might be different from the installed one after update
  • Switching kernels without rebooting can cause mkinitramfs failures
  • System might become unbootable

Recommended workflow:

  1. System update
  2. Reboot when prompted
  3. Then use Kernel Manager to switch/install kernels

Tip: Enable system snapshots (like Snapper) for quick recovery if something goes wrong.

:::

The CachyOS Kernel Manager makes it simple to install and manage kernels from any Arch Linux repository.

To install a kernel. Launch the CachyOS Kernel Manager application and choose the desired kernel by ticking the box [] from the list of all the available options, then just press Execute to start the kernel installation.

To uninstall a kernel, simply uncheck the box [] next to the installed kernel you wish to remove and press Execute again.


:::note The Execute button becomes unavailable when you choose an already installed kernel. :::

Configuring and Building a custom CachyOS Kernel


:::note The CachyOS Kernel Manager is specifically designed to build custom kernels for CachyOS variants and does not support building or configuring a standard Arch Linux kernel or any other variant. :::

To get started. Open the Kernel Manager and click on the Configure button to start adjusting various settings, such as the desired scheduler, tick rate and more. Once you have made your desired changes, click on Build kernel to begin building your custom CachyOS kernel.

Built kernel packages and cache are stored in ~/.cache/cachyos-km/

Available configuration options:

  • Custom package name: With this option, you can name your kernel whatever you want. For example: linux-custom-cachy
  • Scheduler (BORE, RC, RT, RT+BORE, EEVDF and BMQ)
  • Enable CachyOS config
  • Tweak Configuration via nconfig, menuconfig, xconfig, or gconfig
  • Enable/Disable NUMA
  • Enable/Disable Modprobed-db
  • KBUILD CFLAGS (-O3 or -O2)
  • Performance governor as default
  • Enable BBR3
  • Tick rate selection (100Hz, 250Hz, 300Hz, 500Hz, 600Hz, 750Hz, 1000Hz)
  • Tickless mode (idle, periodic, full)
  • Preemption (Full, Voluntary or Server)
  • Transparent Hugepages (Always or Madvise)
  • Enable/Disable DAMON
  • Enable/Disable Automatic CPU arch detection
  • Apply kernel optimization for specific CPU architectures
  • Enable LTO (Full, Thin, No)
  • Build ZFS Module
  • Build NVIDIA Closed Module
  • Build NVIDIA Open Module
  • Include vmlinux with debug information/symbols
  • Load/Save Kernel Manager config preset: (Only presets from the manager itself)
  • Kernel Patches Management (Remote and Local support)

Once the kernel has been successfully built, you will be prompted for your sudo password to install the kernel.

Sched-ext Framework Management

:::caution[Requires a functional polkit agent in order to work properly.] Check the following Arch Wiki page for reference. :::

The Kernel Manager provides a graphical user interface (GUI) for managing and controlling sched-ext schedulers. Access the GUI by clicking on the sched-ext scheduler config button in the main window.


This GUI allows you to:

  • Switch between different sched-ext (scx) schedulers.
  • Enable or disable the scheduler service.
  • Check the currently running scheduler.
  • Set scheduler flags and profiles.

In order to achieve this, the Kernel Manager uses the scx_loader with a configuration stored in /etc/scx_loader.toml.

For more information about the scx_loader configuration file, check this documentation.

  • How does the scx_loader work?
    • Once you have selected the scheduler and profile, the scx_loader will then start the scheduler with the profile that has been selected and save this configuration to the /etc/scx_loader.toml file in order to achieve persistence across reboots. An example of what the file will look like choosing scx_bpfland with the Gaming profile: 
      default_sched = "scx_bpfland"
default_mode = "Gaming"

[scheds.scx_bpfland]
auto_mode = []
gaming_mode = ["-m", "performance"]
lowlatency_mode = ["-k", "-s", "5000", "-l", "5000"]
powersave_mode = ["-m", "powersave"]

Scheduler Profiles

  • What are the "profiles" for?
    • They are presets for the scheduler that modify flags based on proven combinations to enhance effectiveness for specific use cases, such as "Gaming."

Check all the details about the profiles in the scheduler guide.