draw_functrace.py 3.48 KB

Copyright 2008 (c) Frederic Weisbecker <fweisbec@gmail.com>
Licensed under the terms of the GNU GPL License version 2

This script parses a trace provided by the function tracer in
The resulted trace is processed into a tree to produce a more human
view of the call stack by drawing textual but hierarchical tree of
calls. Only the functions's names and the the call time are provided.

	Be sure that you have CONFIG_FUNCTION_TRACER
	# mount -t debugfs nodev /sys/kernel/debug
	# echo function > /sys/kernel/debug/tracing/current_tracer
	$ cat /sys/kernel/debug/tracing/trace_pipe > ~/raw_trace_func
	Wait some times but not too much, the script is a bit slow.
	Break the pipe (Ctrl + Z)
	$ scripts/draw_functrace.py < raw_trace_func > draw_functrace
	Then you have your drawn trace in draw_functrace

import sys, re

class CallTree:
	""" This class provides a tree representation of the functions
		call stack. If a function has no parent in the kernel (interrupt,
		syscall, kernel thread...) then it is attached to a virtual parent
		called ROOT.
	ROOT = None

	def __init__(self, func, time = None, parent = None):
		self._func = func
		self._time = time
		if parent is None:
			self._parent = CallTree.ROOT
			self._parent = parent
		self._children = []

	def calls(self, func, calltime):
		""" If a function calls another one, call this method to insert it
			into the tree at the appropriate place.
			@return: A reference to the newly created child node.
		child = CallTree(func, calltime, self)
		return child

	def getParent(self, func):
		""" Retrieve the last parent of the current node that
			has the name given by func. If this function is not
			on a parent, then create it as new child of root
			@return: A reference to the parent.
		tree = self
		while tree != CallTree.ROOT and tree._func != func:
			tree = tree._parent
		if tree == CallTree.ROOT:
			child = CallTree.ROOT.calls(func, None)
			return child
		return tree

	def __repr__(self):
		return self.__toString("", True)

	def __toString(self, branch, lastChild):
		if self._time is not None:
			s = "%s----%s (%s)\n" % (branch, self._func, self._time)
			s = "%s----%s\n" % (branch, self._func)

		i = 0
		if lastChild:
			branch = branch[:-1] + " "
		while i < len(self._children):
			if i != len(self._children) - 1:
				s += "%s" % self._children[i].__toString(branch +\
								"    |", False)
				s += "%s" % self._children[i].__toString(branch +\
								"    |", True)
			i += 1
		return s

class BrokenLineException(Exception):
	"""If the last line is not complete because of the pipe breakage,
	   we want to stop the processing and ignore this line.

class CommentLineException(Exception):
	""" If the line is a comment (as in the beginning of the trace file),
	    just ignore it.

def parseLine(line):
	line = line.strip()
	if line.startswith("#"):
		raise CommentLineException
	m = re.match("[^]]+?\\] +([0-9.]+): (\\w+) <-(\\w+)", line)
	if m is None:
		raise BrokenLineException
	return (m.group(1), m.group(2), m.group(3))

def main():
	CallTree.ROOT = CallTree("Root (Nowhere)", None, None)
	tree = CallTree.ROOT

	for line in sys.stdin:
			calltime, callee, caller = parseLine(line)
		except BrokenLineException:
		except CommentLineException:
		tree = tree.getParent(caller)
		tree = tree.calls(callee, calltime)

	print CallTree.ROOT

if __name__ == "__main__":