#!/bin/bash
#
# SPDX-License-Identifier: LGPL-2.1-only

CURDIR=$(dirname $0)/
TESTDIR=$CURDIR/..
source $TESTDIR/utils/tap.sh

plan_tests 1

: ${ITERS:=10}
: ${NR_EVENTS:=7000000}
: ${NR_CPUS:=1}

: ${TIME:="./$CURDIR/ptime"}

: ${PROG_NOTRACING:="./$CURDIR/bench1 $NR_CPUS $NR_EVENTS"}
: ${PROG_TRACING:="./$CURDIR/bench2 $NR_CPUS $NR_EVENTS"}

function signal_cleanup ()
{
	killall lttng-sessiond
}

trap signal_cleanup SIGTERM SIGINT

CMD_NOTRACING="$TIME '$PROG_NOTRACING >/dev/null 2>&1'"
CMD_TRACING="$TIME '$PROG_TRACING >/dev/null 2>&1'"

for i in $(seq $ITERS); do
	time_notrace[i]=$(sh -c "$CMD_NOTRACING")
done


lttng-sessiond -d --no-kernel
lttng -q create --snapshot
lttng -q enable-event -u -a
lttng -q start

for i in $(seq $ITERS); do
	time_trace[i]=$(sh -c "$CMD_TRACING")
done

lttng -q stop
lttng -q destroy
killall lttng-sessiond

pass "Trace benchmark"

avg_delta=0
for i in $(seq $ITERS); do
	delta[$i]=$(echo "( ((${time_trace[$i]}) - (${time_notrace[$i]})) / $NR_EVENTS)" | bc -l)
	avg_delta=$(echo "(${avg_delta} + ${delta[$i]})" | bc -l)
done
avg_delta=$(echo "(${avg_delta} / $ITERS)" | bc -l)

std_dev=0
for i in $(seq $ITERS); do
	dev[$i]=$(echo "(( (${delta[$i]}) - (${avg_delta}) ) ^ 2)" | bc -l)
	std_dev=$(echo "( (${std_dev}) + (${dev[i]}) )" | bc -l)
done
std_dev=$(echo "( (${std_dev}) / $ITERS )" | bc -l)
std_dev=$(echo "(sqrt(${std_dev}))" | bc -l)

NS_PER_EVENT=$(echo "($avg_delta * 1000000000)" | bc -l)
# Remove fractions
NS_PER_EVENT=${NS_PER_EVENT%%.*}

STD_DEV_NS_PER_EVENT=$(echo "($std_dev * 1000000000)" | bc -l)
STD_DEV_NS_PER_EVENT=${STD_DEV_NS_PER_EVENT%%.*}

diag "Average tracing overhead per event is ${NS_PER_EVENT}ns, std.dev.: ${STD_DEV_NS_PER_EVENT}ns"