Why Is Swap Usage So High on Linux

What Causes This?

High swap usage on Linux usually means the system is moving memory pages from RAM to disk because physical memory is under pressure. This can happen when too many apps are open, a browser is using several gigabytes of RAM, background services are leaking memory, or the system’s swappiness setting is too aggressive. In some cases, swap stays in use even after RAM pressure drops, which can make the system feel slower than expected.

Common Symptoms

• Apps take longer to open or switch between
• The system feels sluggish even when CPU usage looks normal
• Disk activity stays high while memory usage is near the limit
• Browser tabs or large apps freeze briefly or stutter
• System monitors show swap usage growing over time

How to Fix It Manually

1. Check current memory and swap usage.

   • Open a terminal.
   • Run:

     free -h

   • Look at the Mem and Swap rows. If RAM is nearly full and swap is heavily used, memory pressure is likely the cause.

2. Find the processes using the most memory.

   • In the terminal, run:

     top

     or:

     htop

   • Sort by memory usage if needed.
   • Look for browsers, virtual machines, Electron apps, databases, or any process with unusually high RAM use.
   • Close apps you do not need, or restart a process that appears stuck or leaking memory.

3. Check for background apps and startup services.

   • On Ubuntu or similar desktops, open Startup Applications from the app menu.
   • Disable apps you do not need launching automatically.
   • To review running services, use:

     systemctl --type=service --state=running

   • If you find a nonessential service consuming memory, stop or disable it carefully.

4. Reduce Linux swappiness if it is set too high.

   • Check the current value:

     cat /proc/sys/vm/swappiness

   • A common default is 60. On desktop systems, many users prefer 10 to 20.
   • Temporarily set it to 10:

     sudo sysctl vm.swappiness=10

   • To make it permanent, add this line to /etc/sysctl.conf:

     vm.swappiness=10

5. Clear swap usage by turning swap off and back on.

   • Only do this if you have enough free RAM to hold active data.
   • Run:

     sudo swapoff -a
     sudo swapon -a

   • Check the result again with:

     free -h

   • If the system becomes unstable during swapoff, reboot and close more apps first.

6. Look for memory leaks and update problem apps.

   • If one app keeps growing in RAM usage over time, update it through your package manager or software center.
   • Install system updates as well:

     sudo apt update && sudo apt upgrade

   • If the issue started recently, a buggy extension, driver, or app update may be responsible.

7. Add more RAM or increase swap if the workload is legitimate.

   • If you regularly run heavy workloads like VMs, large code builds, or many browser tabs, your system may simply need more memory.
   • As a short-term workaround, increasing swap can prevent crashes, but it will not be as fast as real RAM.

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