#!/bin/bash
# dom0busy - randomly busies all dom0 vcpus
# keeps cpu busy for a fraction of a second, then sleeps for the same; repeat
# run in domain0 as root, can be monitored in top
TMPFILE=`mktemp /tmp/dom0busy.XXX` || exit 1
(
cat <<'EOF'
#!/bin/bash
while true; do
	RANDOM=$$$(date +%S)
	r1=$RANDOM
	r2=$RANDOM
	let loops="($r1*$r2)%10000"
	start=`date +%s.%N`
	while [ $loops -gt 0 ]; do
		let loops="$loops-1"
	done
	fin=`date +%s.%N`
	elapsed=`echo "scale=3; $fin - $start" | bc -iq`
	#echo sleeping for $elapsed sec
	/bin/sleep $elapsed
done &
EOF
) > $TMPFILE
chmod +x $TMPFILE
ncpus=`xm list | grep Domain-0 | sed 's/  */ /g' | cut -f4 -d" "`
echo Busying $ncpus cpus
let ncpus="$ncpus-1"
while [ $ncpus -ge 0 ]; do
	echo busying cpu $ncpus
	taskset -c $ncpus $TMPFILE
	let ncpus="$ncpus-1"
done
/bin/rm -rf $TMPFILE