Disable THP on RHEL7

Goal

Disable Transparent HugePages persistently, as Oracle recommends for database servers.

Applies to

Red Hat Enterprise Linux 7 hosts running Oracle Database

You'll need

Root access and a server reboot

Result

/sys/kernel/mm/transparent_hugepage/enabled reports [never]

Transparent HugePages (THP) memory is different from standard HugePages memory because the kernel thread allocates memory dynamically during runtime. Standard HugePages memory is pre-allocated at startup, and does not change during runtime. This dynamic memory allocation of THP can cause memory allocation delays during runtime. To avoid performance issues, Oracle recommends that you disable THP on all Oracle Database servers. Oracle recommends that you instead use standard HugePages for enhanced performance.

1. Check Current THP Status

If Transparent Huge Pages is set to [always], it means that it's enabled. Run the following command to confirm:

bash

cat /sys/kernel/mm/transparent_hugepage/enabled

2. Disable THP

Disable transparent huge pages persistently across reboots by appending the GRUB_CMDLINE_LINUX (kernel boot command line) within the /etc/default/grub with “transparent_hugepage=never”. Refer to the example below:

bash

GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="rd.lvm.lv=myvg/swap rd.lvm.lv=myvg/usr vconsole.font=latarcyrheb-sun16 rd.lvm.lv=myvg/root crashkernel=auto vconsole.keymap=us rhgb quiet transparent_hugepage=never"
GRUB_DISABLE_RECOVERY="true"

3. Source Grub Changes

For the grub changes to take effect, run the following command:

bash

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

4. Reboot Host And Confirm

Reboot the server. After reboot, verify that THP is now disabled ([never]) via the following command:

bash

cat /sys/kernel/mm/transparent_hugepage/enabled