I am Angelo. A systems engineer passionate about Linux and all open-source software. Although here I'm just another member of the family.

Limit usable memory size in Linux

Sometimes for one reason or another it is necessary to limit the size of usable memory on Linux. Although not very frequent, it can be useful in complex environments. Let’s start.

Although it is not frequent to find ourselves in this situation, it is true that in complex environments where there are servers with many gigabytes or terabytes of memory, it can be useful to limit the resources they can use.

In this case, the process is much simpler than it seems.

Limit the size of usable memory on Linux

Usually, you already know how much memory you have on your system, but in case you don’t, there are many monitoring tools, but a quick and immediate way is with this command

cat /proc/meminfo | grep MemTotal

You will get an output expressed in KB. For example:

MemTotal: 7780876 kB

In this case, it is a system with only 8Gb.

The magic is done by the mem directive that you have to add to the end of the GRUB_CMDLINE_LINUX line of the /etc/default/grub file

sudo vi /etc/default/grub

It will look like this

Limit usable memory size in Linux
Limit usable memory size in Linux

Of course, on a more real server, you will find more options for this.

Save the changes and to apply them then you have to generate a new configuration file for Grub

sudo grub2-mkconfig -o /boot/grub2/grub.cfg

Finally, reboot the system

sudo reboot

This will suffice


I hope this post will be useful to you at some point, and you will be able to take advantage of it in your work.


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