Is the Transparent Huge Pages (THP) feature enabled on RHEL 6 (x86) 32-bit architecture?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 6 (x86) 32-bit
  • Transparent Huge Pages (THP)
  • redhat_transparent_hugepage

Issue

  • Is Transparent Huge Pages (THP) feature enabled on Red Hat Enterprise Linux 6 (x86) 32-bit architecture ?
  • Why Red Hat Enterprise Linux 6 (x86) 32-bit server does not have "redhat_transparent_hugepage" directory inside /sys/kernel/mm/?
    Eg:
# cat /sys/kernel/mm/redhat_transparent_hugepage/{defrag,enabled}
cat: /sys/kernel/mm/redhat_transparent_hugepage/defrag: No such file or directory
cat: /sys/kernel/mm/redhat_transparent_hugepage/enabled: No such file or directory

Resolution

  • The Transparent Huge Pages (THP) feature is not present on the 32-bit (x86) version of Red Hat Enterprise Linux 6. Install the 64-bit (x86_64) version to enable this feature.

Root Cause

  • The kernel configuration item "CONFIG_TRANSPARENT_HUGEPAGE" is not present in Red Hat Enterprise Linux 6 (x86).

    # grep -i huge /boot/config-2.6.32-358.el6.i686 
    CONFIG_HUGETLBFS=y
    CONFIG_HUGETLB_PAGE=y
    
  • The kernel configuration item "CONFIG_TRANSPARENT_HUGEPAGE" is enabled on Red Hat Enterprise Linux 6 (x86_64).

    # grep -i huge /boot/config-2.6.32-279.9.1.el6.x86_64 
    CONFIG_TRANSPARENT_HUGEPAGE=y
    CONFIG_HUGETLBFS=y
    CONFIG_HUGETLB_PAGE=y
    

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