25 - Memory Usage

1. Check current memory usage

   • free -m

2. Access Linux boot menu

   • sudo systemctl reboot --boot-loader-menu=60

3. Press e on the Linux boot menu.

4. Find the line start with linux then move the cursor to the end of line

5. Press Space then add/edit this line

   • mem=1G

6. Press Ctrl+X to save and reboot

7. Check current memory usage

   • When you look at the total memory column now, you will notice it has drastically shrunk to roughly 954MB ~ 1024 MB (1G), proving your boot intervention worked.

   • free -m

8. Access full details of memory usage

   • less /proc/meminfo

9. Press q to exit

10. The mem=1G will not persist in next reboot

11. [Not in video] Alternate verification method

1. • You should explicitly see mem=1G at the end of the printed command line string.

   • cat /proc/cmdline

student@localhost:~$ cat /proc/cmdline

BOOT_IMAGE=(hd0,gpt2)/vmlinuz-6.12.0-211.26.1.el10_2.x86_64 root=/dev/mapper/rhel-root ro crashkernel=2G-64G:256M,64G-:512M resume=UUID=7f7fdf85-ea53-4a69-8a9f-4b62d9cc96a2 rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet mem=1G