[PATCH 2/2] scripts: show_delta: add --delta-only option

[Erik Stromdahl <erik.stromdahl@gmail.com>]

The --delta-only option makes show_delta print delta time stamps
only (and not the combination of absolute and delta time stamps
which is the default).

Rationale: Easier to diff kernel logs (with graphical diff tool)
when debugging timing issues. Having absolute time stamps
when diffing the output from two different test runs could
potentially (and likely) make the diff tool detect a lot of irrelevant
differences.

Signed-off-by: Erik Stromdahl <erik.stromdahl@gmail.com>
---
 scripts/show_delta | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/scripts/show_delta b/scripts/show_delta
index b85cf0f..13b1f62 100755
--- a/scripts/show_delta
+++ b/scripts/show_delta
@@ -34,6 +34,7 @@ Options:
 		delta timestamps.
 		All delta timestamps will be rounded to the
 		nearest 'round_us' microsecond
+  --delta-only	Add only delta time stamps to the output.
 
 ex: $ dmesg >timefile
     $ show_delta -b NET4 timefile
@@ -73,7 +74,7 @@ def round_delta_ts(delta, rounding_time_us):
 # 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, rounding_time_us):
+def convert_line(line, base_time, rounding_time_us, delta_only):
 	global last_time
 
 	try:
@@ -93,17 +94,23 @@ def convert_line(line, base_time, rounding_time_us):
 	if rounding_time_us:
 		delta = round_delta_ts(delta, rounding_time_us)
 
-	return ("[%5.6f < %5.6f >]" % (time, delta)) + rest
+	if delta_only:
+		return ("[%5.6f]" % delta) + rest
+	else:
+		return ("[%5.6f < %5.6f >]" % (time, delta)) + rest
 
 def main():
 	base_str = ""
 	rounding_str = ""
+	delta_only = False
 	filein = ""
 	for arg in sys.argv[1:]:
 		if arg=="-b":
 			base_str = sys.argv[sys.argv.index("-b")+1]
 		elif arg=="-r":
 			rounding_str = sys.argv[sys.argv.index("-r")+1]
+		elif arg=="--delta-only":
+			delta_only = True
 		elif arg=="-h":
 			usage()
 		else:
@@ -153,6 +160,6 @@ def main():
 		rounding_time_us = 0
 
 	for line in lines:
-		print (convert_line(line, base_time, rounding_time_us),)
+		print (convert_line(line, base_time, rounding_time_us, delta_only),)
 
 main()
-- 
2.7.4