Is Your Server Memory Full? A Quick Linux Command to Free Up Memory!

If your server’s memory usage is too high, causing slow performance or crashes, you can try the following Linux command to quickly free up cached memory:

# This parameter can be used to instruct the kernel to actively free memory caches, but it will not affect running programs.
sync; echo 3 > /proc/sys/vm/drop_caches

Command Explanation

  • <span>sync</span>: Writes data from memory to disk to ensure that data is not lost due to cache release.
  • <span>echo 3 > /proc/sys/vm/drop_caches</span>:
    • <span>0</span> (default) does not free any caches, completely managed by the kernel.
    • <span>1</span> frees page cache
    • <span>2</span> frees directory entry cache and inode cache
    • <span>3</span> frees all of the above caches

Precautions

  1. Do not use frequently: This can affect system performance. The Linux caching mechanism is designed to speed up access, and manual clearing may be counterproductive.
  2. Only use when necessary: For example, when memory resources are very tight.
  3. Not a solution for memory leaks: If an application continuously grows in memory usage, this command is ineffective, and code or service investigation is needed.

You can use the following command to compare memory changes before and after

free -h

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