mongodb 运行时禁用 Transparent Huge Pages详解大数据

Transparent Huge Pages 简称 THP，本来是linux为提高系统性能而做的努力，结果反而成了性能的隐患。mongodb的官方文档明确说明要禁止 linux 的 THP。

检查

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

均应该输出如下
always madvise [never]

临时设置

生产环境发现这个问题后，需要先临时设置，然后再永久设置

#echo 'never' > /sys/kernel/mm/transparent_hugepage/enabled 
#echo 'never' > /sys/kernel/mm/transparent_hugepage/defrag

永久设置

第一种方法

# vi /etc/rc.local 
echo 'never' > /sys/kernel/mm/transparent_hugepage/enabled 
echo 'never' > /sys/kernel/mm/transparent_hugepage/defrag

第二种方法

# vi /etc/init.d/disable-transparent-hugepages: 
 
#!/bin/bash 
### BEGIN INIT INFO 
# Provides:          disable-transparent-hugepages 
# Required-Start:    $local_fs 
# Required-Stop: 
# X-Start-Before:    mongod mongodb-mms-automation-agent 
# Default-Start:     2 3 4 5 
# Default-Stop:      0 1 6 
# Short-Description: Disable Linux transparent huge pages 
# Description:       Disable Linux transparent huge pages, to improve 
#                    database performance. 
### END INIT INFO 
 
case $1 in 
  start) 
    if [ -d /sys/kernel/mm/transparent_hugepage ]; then 
      thp_path=/sys/kernel/mm/transparent_hugepage 
    elif [ -d /sys/kernel/mm/redhat_transparent_hugepage ]; then 
      thp_path=/sys/kernel/mm/redhat_transparent_hugepage 
    else 
      return 0 
    fi 
 
    echo 'never' > ${thp_path}/enabled 
    echo 'never' > ${thp_path}/defrag 
 
    re='^[0-1]+$' 
    if [[ $(cat ${thp_path}/khugepaged/defrag) =~ $re ]] 
    then 
      # RHEL 7 
      echo 0  > ${thp_path}/khugepaged/defrag 
    else 
      # RHEL 6 
      echo 'no' > ${thp_path}/khugepaged/defrag 
    fi 
 
    unset re 
    unset thp_path 
    ;; 
esac

chmod 755 /etc/init.d/disable-transparent-hugepages 
chkconfig --add disable-transparent-hugepages

参考:
IT虾米网
IT虾米网