Oracle 服务器开启大页内存

这是我参与8月更文挑战的第11天，活动详情查看：8月更文挑战

背景环境

Linux 系统，内存超过64G。

参考 Oracle mos 文档

HugePages on Oracle Linux 64-bit (文档 ID 361468.1)
Shell Script to Calculate Values Recommended Linux HugePages / HugeTLB Configuration (文档 ID 401749.1)

步骤

1、修改/etc/security/limits.conf

单位是KB 数值比内存大小要小

vi /etc/security/limits.conf

* soft memlock 846846361 
* hard memlock 846846361

2、使用ulimit-l命令检查memlock数值

su - oracle

$ ulimit -l 
60397977

3、使用 hugepages_settings.sh 脚本生成如下结果

需数据库运行时在oracle用户下执行（执行完后记得敲下回车）

$ ./hugepages_settings.sh 
... 
Recommended setting: vm.nr_hugepages = 1496 $

4、在/etc/sysctl.conf文件中添加内容

vi /etc/sysctl.conf

vm.nr_hugepages = 1496

5、停掉所有数据库实例，重启服务器生效大页配置

6、使用如下命令检查是否生效

# grep HugePages /proc/meminfo 
HugePages_Total: 1496 
HugePages_Free: 485 
HugePages_Rsvd: 446 
HugePages_Surp: 0 

如果HugePages_Total= HugePages_Free 说明大页配置没有生效。

附件 hugepages_settings.sh 脚本内容

 #!/bin/bash
 #
 # hugepages_settings.sh
 #
 # Linux bash script to compute values for the
 # recommended HugePages/HugeTLB configuration
 # on Oracle Linux
 #
 # Note: This script does calculation for all shared memory
 # segments available when the script is run, no matter it
 # is an Oracle RDBMS shared memory segment or not.
 #
 # This script is provided by Doc ID 401749.1 from My Oracle Support 
 # http://support.oracle.com
 
 
 # Welcome text
 echo "
 This script is provided by Doc ID 401749.1 from My Oracle Support 
 (http://support.oracle.com) where it is intended to compute values for 
 the recommended HugePages/HugeTLB configuration for the current shared 
 memory segments on Oracle Linux. Before proceeding with the execution please note following:
  * For ASM instance, it needs to configure ASMM instead of AMM.
  * The 'pga_aggregate_target' is outside the SGA and 
    you should accommodate this while calculating SGA size.
  * In case you changes the DB SGA size, 
    as the new SGA will not fit in the previous HugePages configuration, 
    it had better disable the whole HugePages, 
    start the DB with new SGA size and run the script again.
 And make sure that:
  * Oracle Database instance(s) are up and running
  * Oracle Database 11g Automatic Memory Management (AMM) is not setup 
    (See Doc ID 749851.1)
  * The shared memory segments can be listed by command:
      # ipcs -m
 
 
 
 
 Press Enter to proceed..."
 
 
 read
 
 
 # Check for the kernel version
 KERN=`uname -r | awk -F. '{ printf("%d.%d\n",$1,$2); }'`
 
 
 # Find out the HugePage size
 HPG_SZ=`grep Hugepagesize /proc/meminfo | awk '{print $2}'`
 if [ -z "$HPG_SZ" ];then
     echo "The hugepages may not be supported in the system where the script is being executed."
     exit 1
 fi
 
 
 # Initialize the counter
 NUM_PG=0
 
 
 # Cumulative number of pages required to handle the running shared memory segments
 for SEG_BYTES in `ipcs -m | cut -c44-300 | awk '{print $1}' | grep "[0-9][0-9]*"`
 do
     MIN_PG=`echo "$SEG_BYTES/($HPG_SZ*1024)" | bc -q`
     if [ $MIN_PG -gt 0 ]; then
         NUM_PG=`echo "$NUM_PG+$MIN_PG+1" | bc -q`
     fi
 done
 
 
 RES_BYTES=`echo "$NUM_PG * $HPG_SZ * 1024" | bc -q`
 
 
 # An SGA less than 100MB does not make sense
 # Bail out if that is the case
 if [ $RES_BYTES -lt 100000000 ]; then
     echo "***********"
     echo "** ERROR **"
     echo "***********"
     echo "Sorry! There are not enough total of shared memory segments allocated for 
 HugePages configuration. HugePages can only be used for shared memory segments 
 that you can list by command:
 
 
     # ipcs -m
 
 
 of a size that can match an Oracle Database SGA. Please make sure that:
  * Oracle Database instance is up and running 
  * Oracle Database 11g Automatic Memory Management (AMM) is not configured"
     exit 1
 fi
 
 
 # Finish with results
 case $KERN in
     '2.2') echo "Kernel version $KERN is not supported. Exiting." ;;
     '2.4') HUGETLB_POOL=`echo "$NUM_PG*$HPG_SZ/1024" | bc -q`;
            echo "Recommended setting: vm.hugetlb_pool = $HUGETLB_POOL" ;;
     '2.6') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;
     '3.8') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;
     '3.10') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;
     '4.1') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;
 esac
 
 
 # End

如果数据库版本是11g以后的版本，使用了HUGEPAGE之后 不能使用AMM特性（Automatic Memory Management）否则会提示如下错误 ORA-00845: MEMORY_TARGET not supported on this system