LGL SCX Scheduler Manager

A Qt6 GUI application for managing sched-ext BPF schedulers via scxctl.

USE AT OWN RISK

Features

• Status tab – live view of the running scheduler, mode, and service state; auto-refreshes every 5 seconds with change-detection (no log noise when idle)
• Control tab – start, stop, or switch schedulers with a chosen mode/profile and optional custom flags
• Log tab – timestamped output of all scxctl commands
• Reference tab – descriptions of every scheduler and what workloads each is best suited to
• Flags tab – filterable reference of per-scheduler custom flags with accepted values and descriptions
• System tray – colour-coded indicator (green = running, red = stopped) with quick start/stop actions
• Polkit (pkexec) used for privilege elevation; scxctl list and scxctl get run without root

Prerequisites

scx-tools (provides scxctl and scx_loader)

sudo dnf copr enable bieszczaders/kernel-cachyos-addons
sudo dnf install scx-tools scx-scheds

Recommended — COPR

sudo dnf copr enable linuxgamerlife/lgl-scxctl-manager
sudo dnf install lgl-scxctl-manager

RPM from Releases

Download the .rpm for your Fedora version from GitHub Releases and double-click to install via Discover.

• lgl-scxctl-manager-1.0.1-1.fc43.x86_64.rpm — Fedora 43
• lgl-scxctl-manager-1.0.1-1.fc44.x86_64.rpm — Fedora 44

After installing from Discover, close it and launch the app from your application menu rather than from the Discover install screen.

Build dependencies

sudo dnf install cmake gcc-c++ qt6-qtbase-devel

Building

git clone https://github.com/linuxgamerlife/lgl-scxctl-manager
cd lgl-scxctl-manager
cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(nproc)

Running

./build/lgl-scxctl-manager

A polkit agent must be running (e.g. polkit-gnome-authentication-agent-1 or lxqt-policykit-agent).

Installing system-wide

sudo cmake --install build

Installs the binary to /usr/local/bin and the .desktop file so it appears in your application launcher.

Note: RPM installs place the binary in /usr/bin. The RPM can be uninstalled via your package manager.

Uninstalling

sudo rm /usr/local/bin/lgl-scxctl-manager
sudo rm /usr/share/applications/lgl-scxctl-manager.desktop

Usage

Status Tab

Shows the currently running scheduler, mode, and service state. The Stop Scheduler button is only enabled when a scheduler is actually running. Status auto-refreshes every 5 seconds.

Control Tab

1. Select a scheduler from the dropdown (populated live via scxctl list)
2. Choose a mode: Auto, Gaming, Lowlatency, or Powersave
3. Optionally enter custom flags (see the Flags tab for reference)
4. Click Start (when no scheduler is running) or Switch (to change the active one)
5. Check "Enable scx_loader service on boot" to persist the service across reboots

Reference Tab

A table of all supported schedulers with descriptions of what each is best for, what workloads to avoid, and technical notes.

Flags Tab

A filterable table of per-scheduler custom flags. Use the dropdown to narrow by scheduler. Flags from this table can be pasted directly into the Custom flags field on the Control tab.

Tray Icon

• Green dot = scheduler running
• Red dot = no scheduler active
• Closing the window minimises to tray — the app keeps running
• Double-click to show/hide the window
• Right-click for quick start/stop and Quit to exit fully

Tray support on some desktop environments / window managers (e.g. Niri, Noctalia): a StatusNotifierItem host may be required.

sudo dnf install gnome-shell-extension-appindicator

Tested on Niri Noctalia. Other environments may differ.

Available Schedulers

The scheduler list is populated dynamically from scxctl list. On a typical install this includes:

Scheduler	Best for
scx_bpfland	General desktop, interactive apps — recommended default
scx_beerland	Like bpfland but lower overhead
scx_cake	CachyOS experimental — desktop/gaming
scx_cosmos	General desktop and server, locality-first
scx_flash	Batch jobs, compilation, encoding
scx_lavd	Gaming, audio, low-latency workloads
scx_layered	Power users wanting per-app scheduling policies
scx_nest	Lightly-loaded desktops, turbo-boost workloads
scx_p2dq	Mixed desktop/server, fair load balancing
scx_pandemonium	CachyOS experimental — dynamic task learning
scx_rusty	Multi-core desktops and servers, NUMA systems
scx_rustland	Experimentation and userspace scheduler research
scx_simple	Testing and benchmarking only
scx_tickless	Cloud, virtualisation, HPC, server batch workloads

See the in-app Reference tab for full descriptions and the Flags tab for tuning options.

Notes

• scxctl start, scxctl stop, and scxctl switch require root; the app uses pkexec for elevation
• scxctl list and scxctl get run without root
• Do not run scx.service and scx_loader.service simultaneously
• Disable ananicy-cpp if you experience scheduler watchdog timeouts
• If the scheduler list shows a built-in fallback, ensure scx_loader.service is running: systemctl start scx_loader