#!/bin/ash
# Copyright (c) 2013 - OpenSLX GmbH
#
# This program is free software distributed under the GPL version 2.
# See http://openslx.org/COPYING
#
# If you have any feedback please consult http://openslx.org/feedback and
# send your feedback to feedback@openslx.org
#
# General information about OpenSLX can be found under http://openslx.org
#
# Local hard disk autodetection script for OpenSLX linux stateless clients,
# detecting swap and special partitions

#############################################################################


# Add zram swap
# Some older ubuntu kernels had a problem here, see https://bugs.launchpad.net/ubuntu/+source/linux-lts-raring/+bug/1217189
# So make sure you're up to date

make_swap () {
	[ $# -ne 2 ] && echo "make_swap: Wrong parameter count $#" && exit 1
	local USE="$1"
	local DEV="$2"
	echo "$USE" > "/sys/block/zram${DEV}/disksize"
	mkswap "/dev/zram${DEV}"
	swapon "/dev/zram${DEV}" -p 1000 # high priority (in case we have hdd swap 0x82, prefer zram)
}

CPUS=$(grep -c -E "^processor.*[0-9]+$" "/proc/cpuinfo")
if [ -z "$CPUS" ]; then
	echo "ERROR: Could not determine CPU core count"
	exit 1
fi

[ "$CPUS" -gt "16" ] && CPUS=16 # zram can only handle up to 32 devices, the system can apparently even just handle 29 swap partitions, so use a reasonable upper limit
if ! modprobe zram "num_devices=$CPUS"; then
	echo "ERROR: Could not load zram module"
	exit 1
fi

TOTAL=$(grep ^MemTotal /proc/meminfo | awk '{print $2}')
USE=$(( $TOTAL / ( 2 * $CPUS ) ))
echo "Have $CPUS cores, $TOTAL kb mem, use $USE kb zram swap per core"
USE=$(( $USE * 1024 ))
DEV=0
while [ "$DEV" -lt "$CPUS" ]; do
	make_swap "$USE" "$DEV" &
	LAST=$!
	DEV=$(( $DEV + 1 ))
done

# Wait, so we don't trigger swap.target too early
while kill -0 "$LAST"; do
	usleep 100000
done

exit 0