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ALERT: Disable Transparent HugePages on SLES11, RHEL6, OEL6 and UEK2 Kernels

随着去ioe的潮流越来越汹涌，随着内存越来越便宜，使用Liunx大内存跑核心业务的系统越来越多。因为大内存，多会话，使得配置HugePages也成了必然的选择，在以前的文章中介绍过怎么去配置HugePages以及因为没有配置Hugepage导致的故障.但是随着Linux 6(RedHat 6, OEL 6, SLES 11 and UEK2 kernels等)的广泛应用,他们所在HugePages方面所具有的新特性(Transparent HugePages)很多人可能还没有注意到,Oracle强烈建议无论是rac还是单实例都关闭该特性.

检查是否启用Transparent HugePages方法

To check if the Transparent HugePages are enabled in your server execute the following:

Default/Enabled setting is [always]:

# cat /sys/kernel/mm/transparent_hugepage/enabled

[always] never

Disabled setting is [never]:

# cat /sys/kernel/mm/transparent_hugepage/enabled

always [never]

If "enabled" is NOT set to "[never]", the Transparent HugePages are being used.

You can also issue:

# grep AnonHugePages /proc/meminfo

If the output contains a line like "AnonHugepages: xxxx kB", with a value > 0kB the kernel is using Transparent HugePages.

禁用Transparent HugePages方法

Add the following to the kernel boot line in /etc/grub.conf (this is the preferred method) and reboot the server:

transparent_hugepage=never

Once modified the line will read similar to the following example:

title Oracle Linux Server (2.6.32-300.25.1.el6uek.x86_64)

root (hd0,0)

kernel /vmlinuz-2.6.32-300.25.1.el6uek.x86_64 ro root=LABEL=/ transparent_hugepage=never

initrd /initramfs-2.6.32-300.25.1.el6uek.x86_64.img

OR

Add the following lines in /etc/rc.local and reboot the server:

if test -f /sys/kernel/mm/transparent_hugepage/enabled; then

echo never > /sys/kernel/mm/transparent_hugepage/enabled

fi

if test -f /sys/kernel/mm/transparent_hugepage/defrag; then

echo never > /sys/kernel/mm/transparent_hugepage/defrag

fi

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最权威、专业的Oracle案例资源汇总之案例:Oracle linux redhat检查Transparent HugePages状态并关闭