scripts/show_delta

#!/usr/bin/python
# SPDX-License-Identifier: GPL-2.0-only
#
# show_deltas: Read list of printk messages instrumented with
# time data, and format with time deltas.
#
# Also, you can show the times relative to a fixed point.
#
# Copyright 2003 Sony Corporation
#

import sys
import string

def usage():
print ("""usage: show_delta [<options>] <filename>

This program parses the output from a set of printk message lines which
have time data prefixed because the CONFIG_PRINTK_TIME option is set, or
the kernel command line option "time" is specified. When run with no
options, the time information is converted to show the time delta between
each printk line and the next. When run with the '-b' option, all times
are relative to a single (base) point in time.

Options:
 -h Show this usage help.
 -b <base>	Specify a base for time references.
<base> can be a number or a string.
If it is a string, the first message line
which matches (at the beginning of the
line) is used as the time reference.

ex: $ dmesg >timefile
 $ show_delta -b NET4 timefile

will show times relative to the line in the kernel output
starting with "NET4".
""")
sys.exit(1)

# returns a tuple containing the seconds and text for each message line
# seconds is returned as a float
# raise an exception if no timing data was found
def get_time(line):
if line[0]!="[":
raise ValueError

# split on closing bracket
(time_str, rest) = string.split(line[1:],']',1)
time = string.atof(time_str)

#print "time=", time
return (time, rest)


# average line looks like:
# [ 0.084282] VFS: Mounted root (romfs filesystem) readonly
# time data is expressed in seconds.useconds,
# convert_line adds a delta for each line
last_time = 0.0
def convert_line(line, base_time):
global last_time

try:
(time, rest) = get_time(line)
except:
# if any problem parsing time, don't convert anything
return line

if base_time:
# show time from base
delta = time - base_time
else:
# just show time from last line
delta = time - last_time
last_time = time

return ("[%5.6f < %5.6f >]" % (time, delta)) + rest

def main():
base_str = ""
filein = ""
for arg in sys.argv[1:]:
if arg=="-b":
base_str = sys.argv[sys.argv.index("-b")+1]
elif arg=="-h":
usage()
else:
filein = arg

if not filein:
usage()

try:
lines = open(filein,"r").readlines()
except:
print ("Problem opening file: %s" % filein)
sys.exit(1)

if base_str:
print ('base= "%s"' % base_str)
# assume a numeric base. If that fails, try searching
# for a matching line.
try:
base_time = float(base_str)
except:
# search for line matching <base> string
found = 0
for line in lines:
try:
(time, rest) = get_time(line)
except:
continue
if string.find(rest, base_str)==1:
base_time = time
found = 1
# stop at first match
break
if not found:
print ('Couldn\'t find line matching base pattern "%s"' % base_str)
sys.exit(1)
else:
base_time = 0.0

for line in lines:
print (convert_line(line, base_time),)

main()