翻译mos文章禁用透明大页

Disable Transparent HugePages on SLES11, RHEL6, OL6and UEK2 Kernels

禁用透明大页 文档 ID 1557478.1

应用范围

Oracle Database - Enterprise Edition

Linux x86

Linux x86-64

原因

Because Transparent HugePages are known to cause unexpected node rebootsand performance problems with RAC, Oracle strongly advises to disable the useof Transparent HugePages. In addition, Transparent Hugepages may cause problemseven
in a single-instance database environment with unexpected performanceproblems or delays. As such, Oracle recommends disabling Transparent HugePageson all Database servers running Oracle.

就是说，透明大页会导致oracle节点重启和其他问题，对rac和单机都有效

透明大页的默认设置

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

[always] never

or

cat /sys/kernel/mm/transparent_hugepage/enabled

[always] madvise never

# grepAnonHugePages /proc/meminfo

AnonHugepages: xxxx kB

修改方法：

1.vi /etc/grub.conf 添加粗体

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

2.vi /etc/rc.local 添加下面的代码

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

the two methods need the syste reboot，and then you can use the following line to identify

# grep AnonHugePages /proc/meminfo

AnonHugePages: 0 kB

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

always madvise [never]