TUNED AND THP + READAHEAD

###########
## RHEL6 ##
###########

## Current readahead setting:

sudo blockdev --getra /dev/sda
1024

## Duplicate virtual-guest profile to edit:

sudo cp -r /etc/tune-profiles/virtual-guest /etc/tune-profiles/virtual-guest-mongodb

vi /etc/tune-profiles/virtual-guest-mongodb/ktune.sh

## Existing:

start() {
    	set_cpu_governor performance
        set_transparent_hugepages always
        multiply_disk_readahead 4

        return 0
}

## Necessary THP changes + readahead change:

start() {
    	set_cpu_governor performance
    	set_transparent_hugepages never
    	echo 'never' | tee /sys/kernel/mm/transparent_hugepage/defrag > /dev/null
    	echo 'no' | tee /sys/kernel/mm/transparent_hugepage/khugepaged/defrag > /dev/null
    	multiply_disk_readahead 0

    	return 0
}

## Enable new profile:

sudo tuned-adm profile virtual-guest-mongodb

sudo blockdev --getra /dev/sda
0

## Switch back to verify:

sudo tuned-adm profile virtual-guest

sudo blockdev --getra /dev/sda
1024



############
## RHEL 7 ##
############

## Current readahead setting:

sudo blockdev --getra /dev/sda
8192

## Create new profile and configure:

sudo mkdir /etc/tuned/virtual-guest-mongodb

vi /etc/tuned/virtual-guest-mongodb/tuned.conf

## Add this content:


[main]
summary=MongoDB tuned virtual-guest profile
description=MongoDB tuned profile that adjusts THP and readahead settings
include=virtual-guest

[vm]
transparent_hugepages=never

[disk]
readahead=0

[script]
script=disable_defrag.sh


# Create disable_defrag.shj script to handle the other two THP settings that need to be disabled:

vi /etc/tuned/virtual-guest-mongodb/disable_defrag.sh

## Add this content:


#!/bin/sh

. /usr/lib/tuned/functions

start() {
    echo 'never' | tee /sys/kernel/mm/transparent_hugepage/defrag > /dev/null
    echo 0 | tee /sys/kernel/mm/transparent_hugepage/khugepaged/defrag > /dev/null
    return 0
}

stop() {
    return 0
}

process $@


## Make this script executable:

sudo chmod 755 /etc/tuned/virtual-guest-mongodb/disable_defrag.sh

## Enable new profile:

sudo tuned-adm profile virtual-guest-mongodb

sudo blockdev --getra /dev/sda
0

## Switch back to verify:

sudo tuned-adm profile virtual-guest

sudo blockdev --getra /dev/sda
8192