#!/bin/sh

# Manage VM subsystem in the linux kernel in order to optimize disk I/O when on battery.

VM_WRITEBACK_TIME_POWERSAVE=${VM_WRITEBACK_TIME_POWERSAVE:-true}

help() {
cat <<EOF
--------
$0: VM writeback time parameters.

This hook has 1 tuneable parameter. 
VM_WRITEBACK_TIME_POWERSAVE = controls whether we will try to save power on battery.
Defaults to true.

EOF
}

vm_writeback_time_powersave() {
    [ "$VM_WRITEBACK_TIME_POWERSAVE" = "true" ] || exit $NA
    printf "Setting VM writeback time to %d..." "$1"
    echo $1 > "/proc/sys/vm/dirty_writeback_centisecs" && echo Done. || echo Failed.
}

case $1 in
    true) vm_writeback_time_powersave 1500 ;;
    false) vm_writeback_time_powersave 500 ;;
    help) help;;
    *) exit $NA
esac

exit 0