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Asked: 2024-09-27T07:59:31+05:30 In:

How can I adjust the OOM (Out of Memory) score for a specific process in Ubuntu to influence the kernel’s behavior when managing memory?

I’m trying to figure out how to adjust the OOM (Out of Memory) score for a specific process in Ubuntu, and I’m hoping some of you might have insights on that. I’ve been playing around with some applications that can be really memory-intensive, and it seems like they’re causing my system to choke whenever it runs low on memory. You know how frustrating that can be!

So, here’s the situation: I have a few processes that I want to prioritize over others. For instance, I have a critical application that I can’t afford to have terminated when things get tight. On the flip side, I’ve got these background tasks—maybe some scripts or less important services—that I wouldn’t mind seeing getting killed off first. It feels like the OOM killer is just picking willy-nilly, and I want to take some control over that.

I understand that the OOM score can be adjusted using the `oom_score_adj` value. But honestly, I’m a bit lost on how to actually do that without breaking something in the process. Anyone got a step-by-step guide, or is there a command I should be using? I’ve heard something about using the `/proc` filesystem to tweak these OOM scores, but the specifics are a bit foggy for me.

Also, is this something I can do on-the-fly, or do I need to set it up every time my application starts? Ideally, I want to ensure that my critical process has a much lower OOM score so that it stays alive longer during memory pressure situations. Any tips on best practices for setting this up, or traps I should be aware of?

I’m really hoping there are some Linux wizards out there who can shed some light on this. It’s got to be easier than I’m making it out to be, right? Looking forward to your insights!

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    2 Answers


    1. To adjust the Out of Memory (OOM) score for a specific process in Ubuntu, you’ll primarily use the `oom_score_adj` value, which allows you to modify the OOM score for a given process through the `/proc` filesystem. First, identify the PID (Process ID) of the application you want to adjust. You can find this using the `ps` command. Once you have the PID, you can set the desired OOM score adjustment by echoing a value into the `/proc/[PID]/oom_score_adj` file. A lower value (ranging from -1000 to 1000) gives the process a higher priority, making it less likely to be terminated by the OOM killer. For example, to prioritize a critical application with PID 1234, you would execute: echo -1000 > /proc/1234/oom_score_adj. Conversely, for background tasks that you want to deprioritize, you could set a higher score, such as 1000.

      This adjustment can be performed on-the-fly, meaning you don’t have to set it up every time the application starts. However, if you want these settings to persist across reboots, you can modify the service or the script that starts your application to include the OOM adjustment as part of its startup routine. For example, if you’re using a service manager like systemd, you can include `OOMScoreAdjust=-1000` in the service configuration file for your critical applications. Keep in mind that improper adjustments can lead to unintended system behaviors, so be cautious when adjusting scores, especially for essential system processes. Always test your changes in a safe environment to ensure stability before deploying them in production.




    2. Adjusting OOM Score in Ubuntu

      Adjusting OOM Score in Ubuntu

      To adjust the OOM (Out of Memory) score for specific processes in Ubuntu, you’re on the right track thinking about the oom_score_adj value! This is definitely a cool way to help your critical apps stay alive when things get tight.

      Step-by-Step Guide:

      1. Find the Process ID (PID):
        You need the PID of the process you want to adjust. You can find it using commands like ps aux or pgrep your_application_name.
      2. Check Current OOM Score:
        You can see the current OOM score by running:

                    cat /proc/PID/oom_score
      3. Adjust the OOM Score:
        To adjust the OOM score, use the following command:

                    echo  > /proc/PID/oom_score_adj

        Replace <new_value> with an integer from -1000 to 1000. A lower score means the process is less likely to be killed first. For your critical app, you might want a value closer to -1000.

      4. Verify Changes:
        Check the new score by running:

                    cat /proc/PID/oom_score_adj

      On-the-Fly Changes:

      Yes! You can do this on-the-fly for running processes. But keep in mind, if you restart your application, you’ll need to set it again, as these settings don’t persist after a reboot.

      Best Practices:

      • Always be careful with the oom_score_adj values. A value of -1000 means the process is very protected, which may lead to other processes getting killed off first.
      • If possible, script this adjustment when your application starts for convenience!
      • Check the system logs if your app is getting killed unexpectedly. It’ll help you know if you need to adjust the OOM settings further.

      Things to Watch Out For:

      • Make sure you have the right permissions! You might need to use sudo to make these changes depending on the process.
      • A really low OOM score for many processes can lead to your system becoming unstable, so try to use this sparingly!

      Hopefully, this helps in getting your priority processes sorted out! Good luck!


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