Ubuntu内核启用cgroup CPU实时运行时遇阻，求CONFIG_RT_GROUP_SCHED配置方法

Hey there, I’ve run into this exact issue before—let’s walk through how to enable the missing CONFIG_RT_GROUP_SCHED kernel option so your Docker real-time setup works properly.

What You Need to Know #

The CONFIG_RT_GROUP_SCHED option enables group scheduling for real-time processes (SCHED_FIFO/SCHED_RR), which is a hard requirement for Docker’s --cpu-rt-runtime flag to function. Since your RT kernel didn’t have this enabled by default, we’ll recompile the kernel with this option turned on.

Step 1: Prepare Kernel Source & Configuration #

First, get your existing kernel setup ready:

• Ensure you have the 5.2.9-rt3 kernel source and RT patch applied (you likely already did this when building your initial RT kernel).
• Copy your current kernel config to the source directory (replace ~/linux-5.2.9 with your actual kernel source path):

  cp /boot/config-$(uname -r) ~/linux-5.2.9/.config
  

• Install dependencies for the kernel configuration interface:

  sudo apt update && sudo apt install ncurses-dev build-essential libssl-dev bison flex
  

Step 2: Enable CONFIG_RT_GROUP_SCHED via Menuconfig #

Launch the interactive kernel configuration menu:

cd ~/linux-5.2.9
make menuconfig

Navigate through the menu hierarchy to find the option:

General setup → Control Group support → Group scheduling for SCHED_FIFO/SCHED_RR

Use arrow keys to select this option, then press Y to compile it directly into the kernel (building it as a module with M isn’t recommended here—cgroup support needs this feature available at boot time).

Press ESC twice to exit, and save the configuration when prompted.

Step 3: Recompile & Install the Updated Kernel #

Recompile the kernel (use -j$(nproc) to leverage all your CPU cores for faster builds):

make -j$(nproc)

Install the new kernel modules and kernel itself:

sudo make modules_install
sudo make install

Update GRUB to recognize the modified kernel:

sudo update-grub

Reboot your system to load the updated RT kernel.

Step 4: Verify the Fix #

After rebooting, run the Docker kernel compatibility script again—you should now see:

- CONFIG_RT_GROUP_SCHED: enabled

Try your original Docker run command once more, and it should execute without the "kernel does not support cgroup cpu real-time runtime" error.

Bonus: Use Ubuntu’s Deb-Pkg for Easier Management #

If you prefer building a deb package (simpler to install/reinstall later), replace the compile/install steps with:

make deb-pkg -j$(nproc)

This generates .deb files in the parent directory. Install them with:

sudo dpkg -i ../linux-image-5.2.9-rt3_*.deb ../linux-headers-5.2.9-rt3_*.deb

Then update GRUB and reboot as before.

内容的提问来源于stack exchange，提问作者Baptiste BUSCH