dietpi-distro_comparison

#!/bin/bash
# This script runs a few commands to check resource usage and performance stats.
# It aims to make the comparison of different OS/distro images against each other easy and transparent.
# It aims to replace the very outdated DietPi spreadsheet and comparisons, done in the past:
# - https://docs.google.com/spreadsheets/d/1mDHGZC-H6tU6_O8kuLTG8d4A8Nt7lV1Q7MXTR_6qw30/edit#gid=0
# - https://dietpi.com/phpbb/viewtopic.php?t=262

### IMPORTANT ###
# Execution instructions to assure fair, comparable and reproducible results on all tests:
# - Keep image, boot and system configs untouched, when possible, e.g. DHCP and CPU frequencies.
# - Only when there are significant differences, like one image necessarily requires a static IP to be set, do the same on DietPi via dietpi.txt, to make it better comparable.
# - Use the same console to run the script on both systems, e.g. local console, SSH or serial console.
# - Source the script, instead of executing it, to avoid additional processes and RAM usage for the script execution itself:
#     curl -sSfLO https://raw.githubusercontent.com/MichaIng/hacks/main/dietpi-distro_comparison
#     . ./dietpi-distro_comparison

# Wait for boot/login tasks to finish
while pgrep -f 'postboot' > /dev/null
do
	echo 'Waiting for DietPi-Postboot to finish'
	sleep 1
done
while pgrep -f 'dietpi-update' > /dev/null
do
	echo 'Waiting for DietPi-Update to finish'
	sleep 1
done
while pgrep -f 'apt-get' > /dev/null
do
	echo 'Waiting for APT calls to finish'
	sleep 1
done

# First of all, we bring the OS onto current package state and disable possibly generated swap files to make the comparison fair.
if [[ ! -f '/dietpi-distro_comparison.flag' ]]
then
	echo -e '\nUpgrading all APT packages and removing all swap files...
NB: A flag file will be created to skip this on next script execution.\n'

	# Disabling Bluetooth which leads to hanging boot on RPi's without onboard Bluetooth
	systemctl is-failed hciuart &> /dev/null && systemctl disable --now hciuart

	apt-get -y update
	apt-get -y dist-upgrade
	apt-get -y autopurge

	[[ -f '/boot/dietpi/func/dietpi-set_swapfile' ]] && /boot/dietpi/func/dietpi-set_swapfile 0
	if command -v dphys-swapfile > /dev/null
	then
		dphys-swapfile swapoff
		dphys-swapfile uninstall
	fi
	while read -r file
	do
		swapoff "$file"
		[[ -f $file ]] && rm -v "$file"

	done < <(swapon --show NAME --noheadings | mawk '{print $1}')
	sed -i '/[[:blank:]]swap[[:blank:]]/d' /etc/fstab

	> /dietpi-distro_comparison.flag
	read -rp 'The system will now reboot, press any key to continue...'
	reboot
	exit 0
fi

# Disk usage
total=0
for i in / /boot /boot/efi /boot/firmware
do
	size=$(findmnt -Ufnrbo USED -M "$i")
	(( $size )) || continue
	echo "$i filesystem disk usage: \"findmnt -Ufnrbo USED -M $i\""
	echo "$size bytes"
	((total+=size))
done
echo "Total disk usage:"
echo "$((total/1024**2)) MiB"

echo

# Memory usage
# shellcheck disable=SC2016
echo 'Total memory usage: "free -th | mawk '\''/^Total:/{print $3}'\''"'
free -th | mawk '/^Total:/{print $3}'

echo

# Pre-installed packages
echo 'Number of pre-installed DEB packages: "dpkg --get-selections | wc -l"'
dpkg --get-selections | wc -l

echo

# Processes
# shellcheck disable=SC2016
echo 'Number of running processes: "echo $(( $(pstree -Ta | wc -l) - 3 ))" (minus echo, pstree and wc)'
echo $(( $(pstree -Ta | wc -l) - 3 ))

echo

# Boot duration
# shellcheck disable=SC2016
echo 'Boot duration: "systemd-analyze | mawk '\''{print $(NF-1)" "$NF;exit}'\''"'
systemd-analyze | mawk '{print $(NF-1)" "$NF;exit}'

echo

# Check for /tmp mount
tmp_mount=$(findmnt -Ufnro FSTYPE -M /tmp)
if [[ ! $tmp_mount ]]
then
	echo '/tmp is no dedicated mount, which is bad since volatile files lead to rootfs disk I/O.'
	
elif [[ $tmp_mount == 'tmpfs' ]]
then
	echo '/tmp is a tmpfs, which is good to reduce disk I/O.'
	
elif [[ $tmp_mount == 'ramfs' ]]
then
	echo '/tmp is a ramfs, which is good to reduce disk I/O, but better switch to successor tmpfs.'
	
elif [[ $(findmnt -Ufnro SOURCE -M /tmp) == *'zram'* ]]
then
	echo '/tmp is a zram mount, which is good to reduce disk I/O with minimal additional memory usage, but at the cost of additional CPU utilisation for (de)compression.'
else
	echo '/tmp is a dedicated mount, which is good to reduce disk I/O on rootfs, but it is no (known) RAM disk.'
fi

echo

# Check for /var/log mount
log_mount=$(findmnt -Ufnro FSTYPE -M /var/log)
if [[ ! $log_mount ]]
then
	echo '/var/log is no dedicated mount, which is bad for disk I/O, but logs are preserved on system crash.'
	
elif [[ $log_mount == 'tmpfs' ]]
then
	echo '/var/log is a tmpfs, which is good to reduce disk I/O, but logs are lost on system crash.'
	
elif [[ $log_mount == 'ramfs' ]]
then
	echo '/var/log is a ramfs, which is good to reduce disk I/O, but logs are lost on system crash. Also better switch to successor tmpfs.'
	
elif [[ $(findmnt -Ufnro SOURCE -M /var/log) == *'zram'* ]]
then
	echo '/var/log is a zram mount, which is good to reduce disk I/O with minimal additional memory usage, but at the cost of additional CPU utilisation for (de)compression. Logs are however lost on system crash.'
else
	echo '/var/log is a dedicated mount, which is good to reduce disk I/O on rootfs. Since it is no (known) RAM disk, logs create disk I/O on another drive, but survive system crashes.'
fi

echo

# SSH
if ss -tln | grep -q ':22'
then
	echo 'This image comes with an SSH server pre-installed.'
	[[ $SSH_TTY ]] && echo 'The script was executed from within an SSH session, which increases the process count above by one, compared to a local console session.
Assure to run the script via SSH as well on other systems you want to compare.'
else
	echo 'This image has no SSH server pre-installed.'
fi

echo