LINUX HUGEPAGES在大記憶體資料庫中的應用

[root@rehl6 ~]# more /etc/redhat-release

Red Hat Enterprise Linux Server release 6.2 (Santiago)

[root@rehl6 ~]# uname -a

Linux rehl6 2.6.32-220.el6.x86_64 #1 SMP Wed Nov 9 08:03:13 EST 2011 x86_64 x86_64 x86_64 GNU/Linux

[root@rehl6 ~]# grep Huge /proc/meminfo

AnonHugePages:   1142784 kB

HugePages_Total:       0

HugePages_Free:        0

HugePages_Rsvd:        0

HugePages_Surp:        0

Hugepagesize:       2048 kB

ALTER SYSTEM RESET memory_target SCOPE=SPFILE;

ALTER SYSTEM RESET memory_max_target SCOPE=SPFILE;

ALTER SYSTEM SET sga_target=g SCOPE=SPFILE;

ALTER SYSTEM SET pga_aggregate_target=g SCOPE=SPFILE;

SHUTDOWN IMMEDIATE;

STARTUP;

#!/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

#

# Welcome text

echo "

This script is provided by Doc ID 401749.1 from My Oracle Support

() 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

    '2.4') 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" ;;

     *) echo "Unrecognized kernel version $KERN. Exiting." ;;

esac

# End