The Red Hat’s documentation that you did link to is about RHEL 6. The RHEL 6 had legacy GRUB.
AlmaLinux 8 is clone of RHEL 8. AlmaLinux has GRUB2. Hence the instructions to configure it do not match.
GRUB2 has its configuration in either
/boot/grub2/grub.cfg (if system uses legacy BIOS mode) or
/boot/efi/EFI/almalinux/grub.cfg (if EFI us in use). Only one of them should exists.
/etc/grub2-efi.cfg are symbolic links to those files.
First thing is thus to figure out which do you have. Run as root:
ls -l /etc/grub2*
Next thing is to look at the configuration. Run:
My system has:
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_CMDLINE_LINUX="resume=UUID=47..98 nouveau.modeset=0 rd.driver.blacklist=nouveau plymouth.ignore-udev"
If I did want the acpi=off, then I would edit the GRUB_CMDLINE_LINUX to be:
GRUB_CMDLINE_LINUX="resume=UUID=47..98 acpi=off nouveau.modeset=0 rd.driver.blacklist=nouveau plymouth.ignore-udev"
However, before you do any edits, I’d recommend that you reboot and in the interactive GRUB menu, during boot, edit the kernel command-line parameters; add the
acpi=off, boot system, and check your logs whether the parameter has desired effect. The changes you do interactively are not persistent.
When you are sure that you want acpi=off on every boot, then edit the
/etc/default/grub and then run
grub2-mkconfig -o the_grub.cfg_in_your_system
The command creates content of grub.cfg and writes it to file that the -o specifies. Without -o filename the
grub2-mkconfigwrites to stdout.
Have you set in EFI that CPU can use all cores? It tends to be the default, but for some reason server BIOS/EFI usually has option to limit number of cores.