If you notice in Oracle Linux 5.6, Oracle starts to disable NUMA at boot time as shown in the following grub.conf file:

[root@rac561 ~]# cat /etc/grub.conf
# grub.conf generated by anaconda
# Note that you do not have to rerun grub after making changes to this file
# NOTICE:  You do not have a /boot partition.  This means that
#          all kernel and initrd paths are relative to /, eg.
#          root (hd0,0)
#          kernel /boot/vmlinuz-version ro root=/dev/sda1
#          initrd /boot/initrd-version.img
title Oracle Linux Server (2.6.32-100.26.2.el5uek)
        root (hd0,0)
        kernel /boot/vmlinuz-2.6.32-100.26.2.el5 ro root=/dev/sda1 rhgb quiet numa=off
        initrd /boot/initrd-2.6.32-100.26.2.el5.img

Looking at /proc/cmdline, you will notice that the numa=off argument was passed at boot:

[root@rac561 ~]# cat /proc/cmdline
ro root=/dev/sda1 rhgb quiet numa=off

Posted by Charles Kim, Oracle ACE Director