#!/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"

Thisscript is provided by Doc ID 401749.1 from My Oracle Support

(http://support.oracle.com)where it is intended to compute values for

therecommended HugePages/HugeTLB configuration for the current shared

memorysegments on Oracle Linux. Before proceeding with the execution pleasenote following:

*For ASM instance, it needs to configure ASMM instead of AMM.

*The pga_aggregate_target is outside the SGA and

youshould accommodate this while calculating the overall size.

*In case you changes the DB SGA size,

asthe new SGA will not fit in the previous HugePages configuration,

ithad better disable the whole HugePages,

startthe DB with new SGA size and run the script again.

Andmake sure that:

*Oracle Database instance(s) are up and running

*Oracle Database 11g Automatic Memory Management (AMM) is not setup

(SeeDoc ID 749851.1)

*The shared memory segments can be listed by command:

#ipcs -m

PressEnter to proceed..."

read

#Check for the kernel version

KERN=`uname-r | awk -F. { printf("%d.%d ",$1,$2); }`

#Find out the HugePage size

HPG_SZ=`grepHugepagesize /proc/meminfo | awk {print $2}`

if[ -z "$HPG_SZ" ];then

echo"The hugepages may not be supported in the system where thescript is being executed."

exit1

fi

#Initialize the counter

NUM_PG=0

#Cumulative number of pages required to handle the running sharedmemory segments

forSEG_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 segmentsallocated for

HugePagesconfiguration. HugePages can only be used for shared memory segments

thatyou can list by command:

#ipcs -m

ofa 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 notconfigured"

exit1

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" ;;

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" ;;

4.14)echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;

*)echo "Kernel version $KERN is not supported by this script(yet). Exiting." ;;

esac

#End