hugepages_settings.sh-Shell Script to Calculate Values Recommended Linux HugePages-HugeTLB Configuration_DocID401749.1

Oracle Linux-Shell Script to Calculate Values Recommended Linux HugePages-HugeTLB Configuration_DocID401749.1
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---- hugepages_settings.sh
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!/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 the overall 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" ;;
'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" ;;
'4.18') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;
'5.4') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;
*) echo "Kernel version $KERN is not supported by this script (yet). Exiting." ;;
esac

End