NUMA disable

Issue

• How to disable NUMA in Red Hat Enterprise Linux system?

Resolution

• Adding the "numa=off" to kernel command line in boot loader configuration and rebooting the system will disable NUMA awareness.

Examples:

• RHEL6 or earlier (/boot/grub/grub.conf)
• Raw

      title Red Hat Enterprise Linux AS (2.6.9-55.EL)
              root (hd0,0)
              kernel /vmlinuz-2.6.9-55.EL ro root=/dev/VolGroup00/LogVol00 rhgb quiet numa=off
              initrd /initrd-2.6.9-55.EL.img
  

• RHEL7 or later (/etc/default/grub)Please note, grub config has to be rebuilt for changes to take effect:
• Raw

  # grub2-mkconfig -o /etc/grub2.cfg
  

• Raw

      GRUB_CMDLINE_LINUX="rd.lvm.lv=rhel_vm-210/root rd.lvm.lv=rhel_vm-210/swap vconsole.font=latarcyrheb-sun16 crashkernel=auto  vconsole.keymap=us rhgb quiet numa=off"
  

• To modify grub from RHEL8 and later refer: How do I permanently modify the kernel command line in RHEL 8 or 9?

Root Cause

• NUMA cannot be disabled, but kernel can handle all memory as a single NUMA node. /usr/share/doc/kernel-doc-4.18.0/Documentation/x86/x86_64/boot-options.txt describes the option as follows.
• Raw

    numa=off      Only set up a single NUMA node spanning all memory.