Linux Drop Caches - Shell-Bash

As a programmer, you may have encountered situations where your Linux system is running slowly due to a lack of free memory. One way to resolve this issue is to clear the unused memory caches using the Linux 'drop_caches' command.

What are Linux Memory Caches?

Linux uses memory caching to store frequently accessed data temporarily in RAM, thereby accelerating the system's performance. Some common types of memory caches include:

• Page cache: Contains file system data and metadata from disk.
• Inode cache: Stores information about files and directories.
• Dentries cache: Stores information about directory entries.

How to Clear Memory Caches in Linux?

To clear the memory caches in Linux using the 'drop_caches' command, you need to be a superuser or have root access. The following commands can be used:

# To clear both page cache and dentries/inode cache:
$ echo 1 | sudo tee /proc/sys/vm/drop_caches

# To clear only the page cache:
$ echo 2 | sudo tee /proc/sys/vm/drop_caches

# To clear only the dentries/inode cache:
$ echo 3 | sudo tee /proc/sys/vm/drop_caches

Once executed, the 'drop_caches' command will release the memory occupied by these caches, freeing up valuable space.

When to Use the 'drop_caches' Command?

It is important to note that the 'drop_caches' command should not be used blindly. Clearing the memory caches can cause a performance drop if the freed memory was recently used by processes or applications. It is usually a good idea to use this command when the system is experiencing a slowdown or after closing intensive memory-consuming processes or applications.

Also, regular use of this command is not advisable as it may cause performance degradation over time, as the system will need to reload previously cached data into memory.

Conclusion

Linux memory caching is a powerful system feature that enhances the overall performance of your system. However, if your system is running low on memory resources or experiencing slow-downs, the 'drop_caches' command can be used to clear the memory caches and improve system performance.