配置 HugePages for Oracle on Linux (x86-64)

1 查看当前hugepages配置情况

$ grep Huge /proc/meminfo

HugePages_Total: 0

HugePages_Free: 0

HugePages_Rsvd: 0

HugePages_Surp: 0

Hugepagesize: 2048 kB

2 计算需要设置hugepags大小(依赖sag 的大小)

以下是oracle 官方提供的脚本

创建一个文件hugepages_setting.sh

#!/bin/bash
#
# hugepages_settings.sh
#
# Linux bash script to compute values for the
# recommended HugePages/HugeTLB configuration
#
# 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. 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" ;;
esac

# End

文件授权

chmod u+x hugepages_setting.sh

执行脚本

$ ./hugepages_settings.sh

Recommended setting: vm.nr_hugepages = 191

手动计算公式

例：一台物理机内存为256G，此时的

nr_hugepages = （256+2）*1024/2 = 132096

3 设置

vi /etc/sysctl.conf

增加vm.nr_hugepages = 191 保存

执行 sysctl -p

4 编辑 /etc/security/limits.conf

增加一下内容:

memlock应稍小于物理内存，未开启大页情况下为3145728（单位KB），开启大页后至少应为物理内存的90%

配置 HugePages for Oracle on Linux (x86-64)

oracle soft memlock 3145728 #unlimited

oracle hard memlock 3145728 #unlimited

5 重启服务器和数据库

6 查询是否生效

$ grep Huge /proc/meminfo

HugePages_Total: 192

HugePages_Free: 52

HugePages_Rsvd: 49

HugePages_Surp: 0

Hugepagesize: 2048 kB

配置完成

注意:

oracle 11g 下需要关闭AMM

memory_max_target big integer 0

memory_target big integer 0

配置 HugePages for Oracle on Linux (x86-64)

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