#!/bin/ash
# 
# Script to set the CPU governor to ondemand on all cores
#

# source global config
. /opt/openslx/config || \
	{ echo "ERROR: Could not source /opt/openslx/config."; exit 1; }

# set the governor to the one given in SLX_GOVERNOR
TARGET_GOVERNOR=""
if [ -n "$SLX_GOVERNOR" ]; then
	TARGET_GOVERNOR="$SLX_GOVERNOR"
else
	# use 'ondemand' per default
	TARGET_GOVERNOR="ondemand"
fi
echo "Trying to set CPU governor to $TARGET_GOVERNOR"
# global information needed
# CORES is the range of cores present, on bwpc4 it has the value '0-3'
# thus the split: MINCORE=0 MAXCORE=3
CORES="$(cat /sys/devices/system/cpu/present)"
MINCORE="$(echo $CORES | awk -F "-" '{print $1}')"
MAXCORE="$(echo $CORES | awk -F "-" '{print $2}')"

# Helper function 'test_for_gov'
# Usage:
#	test_for_gov <governor>
# Example:
#	test_for_gov "ondemand"
# Return 0 if it is supported by all cpus, 1 otherwise
test_for_gov() {
	# if no argument is given, print error and exit (yes exit the whole script!)
	[ $# -ne 1 ] && echo "Usage: test_for_gov <governor>. No arguments given!" && exit 1
	local GOVERNOR="$1"

	# check for each cpu just to be safe
	# ash-style loop ....
	local i=$MINCORE
	while [ $i -le $MAXCORE ]; do
		# check if the given governor is supported
		grep -q "${GOVERNOR}" /sys/devices/system/cpu/cpu${i}/cpufreq/scaling_available_governors 2>/dev/null || return 1;
		# increment
		true $(( i++ ))
	done
	return 0;
}
# now actually test the cpus for the 'ondemand' cpu governor
if test_for_gov "${TARGET_GOVERNOR}"; then
	# ok, so now set the governor to 'ondemand' for all cores
	i=$MINCORE
	while [ $i -le $MAXCORE ]; do
		if ! echo "${TARGET_GOVERNOR}" > /sys/devices/system/cpu/cpu${i}/cpufreq/scaling_governor; then
			echo "ERROR: Could not set the cpu governor to '${TARGET_GOVERNOR}'!"
			exit 1
		fi
		true $(( i++ ))
	done
else
	echo "ERROR: '${TARGET_GOVERNOR}' is not supported by this machine!"
	exit 0
fi