Oracle recommends that you disable Transparent HugePages before you start installation.
Transparent HugePages memory differs from standard HugePages memory because the kernel
khugepaged thread allocates memory dynamically during runtime. Standard HugePages memory is pre-allocated at startup, and does not change during runtime.
Note:Although Transparent HugePages is disabled on UEK2 and later UEK kernels, Transparent HugePages may be enabled by default on your Linux system.
Transparent HugePages memory is enabled by default with SUSE 12, Red Hat Enterprise Linux 7, and Oracle Linux 7 with earlier releases of Oracle Linux with the Unbreakable Enterprise Kernel 2 (UEK2) kernels.
Transparent HugePages can cause memory allocation delays during runtime. To avoid performance issues, Oracle recommends that you disable Transparent HugePages on all Oracle Database servers. Oracle recommends that you instead use standard HugePages for enhanced performance.
To check if Transparent HugePages is enabled, run one of the following commands as the
Red Hat Enterprise Linux kernels:
# cat /sys/kernel/mm/redhat_transparent_hugepage/enabled
# cat /sys/kernel/mm/transparent_hugepage/enabled
The following is a sample output that shows Transparent HugePages are being used as the [always] flag is enabled.
If Transparent HugePages is removed from the kernel, then neither
/sys/kernel/mm/redhat_transparent_hugepage files exist.
To disable Transparent HugePages:
For Oracle Linux 7 and Red Hat Enterprise Linux 7, add or modify the transparent_hugepage=never parameter in the
RUB_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="crashkernel=auto rhgb quiet numa=off transparent_hugepage=never" GRUB_DISABLE_RECOVERY="true"
Note:The file name may vary for your operating systems. Check your operating system documentation for the exact file name and the steps to disable Transparent HugePages.
grub2–mkconfigcommand to regenerate the
# grub2-mkconfig -o /boot/grub2/grub.cfg
Restart the system to make the changes permanent.