[root@localhost tools]#  bash -xv hptweaks.sh
#!/bin/bash
#############################################################
# tweaks for centminmod.com LEMP stacks on CentOS 6/7
# centos transparent huge pages calculations for allocation
# of nr.hugepages and max locked memory system limits
# https://www.kernel.org/doc/Documentation/vm/hugetlbpage.txt
#############################################################

CENTOSVER=$(awk '{ print $3 }' /etc/redhat-release)
++ awk '{ print $3 }' /etc/redhat-release
+ CENTOSVER=6.7

if [ "$CENTOSVER" == 'release' ]; then
    CENTOSVER=$(awk '{ print $4 }' /etc/redhat-release | cut -d . -f1,2)
    if [[ "$(cat /etc/redhat-release | awk '{ print $4 }' | cut -d . -f1)" = '7' ]]; then
        CENTOS_SEVEN='7'
    fi
fi
+ '[' 6.7 == release ']'

if [[ "$(cat /etc/redhat-release | awk '{ print $3 }' | cut -d . -f1)" = '6' ]]; then
    CENTOS_SIX='6'
fi
++ cat /etc/redhat-release
++ awk '{ print $3 }'
++ cut -d . -f1
+ [[ 6 = \6 ]]
+ CENTOS_SIX=6

    # check if redis installed as redis server requires huge pages disabled
    if [[ ! "$(rpm -ql redis | grep not)" ]]; then
        if [[ -f /sys/kernel/mm/redhat_transparent_hugepage/enabled ]]; then
            echo never > /sys/kernel/mm/transparent_hugepage/enabled
        fi
    fi
++ rpm -ql redis
++ grep not
+ [[ ! -n '' ]]
+ [[ -f /sys/kernel/mm/redhat_transparent_hugepage/enabled ]]
+ echo never

if [[ -f /sys/kernel/mm/redhat_transparent_hugepage/enabled ]]; then
    HP_CHECK=$(cat /sys/kernel/mm/redhat_transparent_hugepage/enabled | grep -o '\[.*\]')
    if [[ "$CENTOS_SIX" = '6' && "$HP_CHECK" = '[always]' ]]; then
        FREEMEM=$(cat /proc/meminfo | grep MemFree | awk '{print $2}')
        NRHUGEPAGES_COUNT=$(($FREEMEM/8/2048/16*16))
        MAXLOCKEDMEM_COUNT=$(($FREEMEM/8/2048/16*16*4))
        MAXLOCKEDMEM_SIZE=$((MAXLOCKEDMEM_COUNT*1024))
    elif [[ "$CENTOS_SEVEN" = '7' && "$HP_CHECK" = '[always]' ]]; then
        FREEMEM=$(cat /proc/meminfo | grep MemAvailable | awk '{print $2}')
        NRHUGEPAGES_COUNT=$(($FREEMEM/8/2048/16*16))
        MAXLOCKEDMEM_COUNT=$(($FREEMEM/8/2048/16*16*4))
        MAXLOCKEDMEM_SIZE=$((MAXLOCKEDMEM_COUNT*1024))
    fi

    if [[ "$HP_CHECK" = '[always]' ]]; then
        echo
        echo "set vm.nr.hugepages in /etc/sysctl.conf"
        if [[ -z "$(grep '^vm.nr_hugepages' /etc/sysctl.conf)" ]]; then
            echo "vm.nr_hugepages=$NRHUGEPAGES_COUNT" >> /etc/sysctl.conf
            sysctl -p
        else
            sed -i "s|vm.nr_hugepages=.*|vm.nr_hugepages=$NRHUGEPAGES_COUNT|" /etc/sysctl.conf
            sysctl -p
        fi
        echo
        echo "set system max locked memory limit"
        echo
        echo "/etc/security/limits.conf"
        echo "* soft memlock $MAXLOCKEDMEM_SIZE"
        echo "* hard memlock $MAXLOCKEDMEM_SIZE"
        if [[ -z "$(grep '^memlock' /etc/security/limits.conf)" ]]; then
            echo "* soft memlock $MAXLOCKEDMEM_SIZE" >> /etc/security/limits.conf
            echo "* hard memlock $MAXLOCKEDMEM_SIZE" >> /etc/security/limits.conf
            echo
        else
            sed -i "s|memlock .*|memlock $MAXLOCKEDMEM_SIZE|g" /etc/security/limits.conf
        fi
        cat /etc/security/limits.conf
        echo
    fi
elif [[ "$HP_CHECK" = '[never]' ]]; then
    echo
    echo "transparent huge pages not enabled"
    echo "no tweaks needed"
    echo
else
    echo
    echo "transparent huge pages not supported"
    echo "no tweaks needed"
    echo
fi
+ [[ -f /sys/kernel/mm/redhat_transparent_hugepage/enabled ]]
++ cat /sys/kernel/mm/redhat_transparent_hugepage/enabled
++ grep -o '\[.*\]'
+ HP_CHECK='[never]'
+ [[ 6 = \6 ]]
+ [[ [never] = \[\a\l\w\a\y\s\] ]]
+ [[ '' = \7 ]]
+ [[ [never] = \[\a\l\w\a\y\s\] ]]