Under Linux, how to set up the OOM killer to kill the process that takes the most memory?
May 7, 12:03am

To set up the OOM killer to kill the process that takes the most memory, you can adjust the oom_score_adj value for each process. The oom_score_adj value ranges from -1000 to 1000, where a lower value makes a process less likely to be killed by the OOM killer.

Here are the steps to adjust the oom_score_adj value:

  1. Identify the Process ID (PID) of the process you want to protect or make more likely to be killed. You can use commands like ps aux or top to find the PID.

  2. Adjust the oom_score_adj value for the process. For example, to make a process less likely to be killed, you can set its oom_score_adj value to -1000:

    bash
    echo -1000 | sudo tee /proc/[PID]/oom_score_adj

    Replace [PID] with the actual Process ID of the process you want to adjust.

  3. To make a process more likely to be killed, you can set its oom_score_adj value to a higher number, such as 1000:

    bash
    echo 1000 | sudo tee /proc/[PID]/oom_score_adj

  4. If you want to ensure that a critical process is never killed by the OOM killer, you can set its oom_score_adj value to -1000. This will make the OOM killer prioritize other processes for termination.

  5. Monitor the oom_score and oom_score_adj values of your processes to ensure they are set correctly. You can view these values in the /proc/[PID]/ directory.

By adjusting the oom_score_adj value, you can influence the OOM killer's decision-making process and protect critical processes from being terminated.

May 7, 12:04am
I cannot use oom_score_adj because I don't know which process takes the most memory. The kernel should know dynamically.
May 7, 12:06am

To configure the Linux OOM killer to automatically target the process consuming the most memory, you can use the earlyoom daemon. Earlyoom is a user-space daemon that aims to trigger the OOM killer earlier and more predictably, helping to avoid system hangs and unresponsiveness due to memory exhaustion.

Here’s how you can set it up:

  1. Install earlyoom:
    You can install earlyoom from your distribution’s package manager. For example, on Debian-based systems, you can use:

    bash
    sudo apt-get install earlyoom

  2. Configure earlyoom:
    The default configuration should work for most users, but you can customize it by editing the configuration file, usually located at /etc/default/earlyoom. You can adjust parameters like the memory threshold at which earlyoom should trigger the OOM killer.

  3. Enable and Start earlyoom:
    Enable the earlyoom service to start on boot and start it immediately:

    bash
    sudo systemctl enable earlyoom
sudo systemctl start earlyoom

Earlyoom will monitor the system’s memory usage and trigger the OOM killer when the available memory falls below a certain threshold. It is designed to kill the process with the highest memory consumption, which aligns with your requirement to target the process using the most memory.

By using earlyoom, you can ensure that the OOM killer is invoked earlier and more predictably, helping to maintain system stability and responsiveness.

May 7, 12:06am

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