ftracegraph

#!/bin/bash

# ftracegraph:
#  A wrapper script for ftrace graph functionality, making it easy and quick to use.
#  Runs a given command and writes the function graphs trace into /tmp/ftracegraph.out
#
#  Usage:
#     ftracegraph <function-to-graph> <depth> <filter|noop> <cmd-to-run>"
#
#  Examples:
#     ftracegraph btrfs_file_write_iter 2 noop "fs_mark -d /btrfs -D 2 -N 1 -L 1 -S 1 -s 65536"'
#     ftracegraph btrfs_buffered_write 2 "*:mod:btrfs" "fs_mark -d /btrfs -D 2 -N 1 -L 1 -S 1 -s 65536"'

useas()
{
	echo Usage:
	echo "  ftracegraph <function-to-graph> <depth> <filter|noop> <cmd-to-run>"
	echo "Examples:"
	echo '  ftracegraph btrfs_file_write_iter 2 noop "fs_mark -d /btrfs -D 2 -N 1 -L 1 -S 1 -s 65536"'
	echo '  ftracegraph btrfs_buffered_write 2 "*:mod:btrfs" "fs_mark -d /btrfs -D 2 -N 1 -L 1 -S 1 -s 65536"'
}

trap useas EXIT

: ${1?"arg1 <function-to-trace missing"} && func=$1
: ${2?"arg2 <depth>"} && depth=$2
: ${3?"arg3 <filter>"} && filter=$3
: ${4?"arg4 <cmd-to-run missing"} && cmd=$4

trap - EXIT

dir=/sys/kernel/debug/tracing
trace-cmd reset

sysctl kernel.ftrace_enabled=1

echo function_graph > ${dir}/current_tracer
echo $depth > ${dir}/max_graph_depth
echo > ${dir}/set_ftrace_filter
if [ $filter != "noop" ]
then
	for i in ${filter}
	do
		echo $i >> ${dir}/set_ftrace_filter
	done
fi
echo 1 > ${dir}/tracing_on

echo "${func}" > ${dir}/set_graph_function

echo $cmd | bash

echo 0 > ${dir}/tracing_on

cat ${dir}/trace > /tmp/ftracegraph.out
trace-cmd reset
echo "Wrote trace to /tmp/ftracegraph.out"