1 files changed, 45 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf-diff.txt b/tools/perf/Documentation/perf-diff.txt
index a79c84ae61aa..036d65bded51 100644
--- a/tools/perf/Documentation/perf-diff.txt
+++ b/tools/perf/Documentation/perf-diff.txt
@@ -118,6 +118,51 @@ OPTIONS
 	sum of shown entries will be always 100%.  "absolute" means it retains
 	the original value before and after the filter is applied.
 
+--time::
+	Analyze samples within given time window. It supports time
+	percent with multiple time ranges. Time string is 'a%/n,b%/m,...'
+	or 'a%-b%,c%-%d,...'.
+
+	For example:
+
+	Select the second 10% time slice to diff:
+
+	  perf diff --time 10%/2
+
+	Select from 0% to 10% time slice to diff:
+
+	  perf diff --time 0%-10%
+
+	Select the first and the second 10% time slices to diff:
+
+	  perf diff --time 10%/1,10%/2
+
+	Select from 0% to 10% and 30% to 40% slices to diff:
+
+	  perf diff --time 0%-10%,30%-40%
+
+	It also supports analyzing samples within a given time window
+	<start>,<stop>. Times have the format seconds.microseconds. If 'start'
+	is not given (i.e., time string is ',x.y') then analysis starts at
+	the beginning of the file. If stop time is not given (i.e, time
+	string is 'x.y,') then analysis goes to the end of the file. Time string is
+	'a1.b1,c1.d1:a2.b2,c2.d2'. Use ':' to separate timestamps for different
+	perf.data files.
+
+	For example, we get the timestamp information from 'perf script'.
+
+	  perf script -i perf.data.old
+	    mgen 13940 [000]  3946.361400: ...
+
+	  perf script -i perf.data
+	    mgen 13940 [000]  3971.150589 ...
+
+	  perf diff --time 3946.361400,:3971.150589,
+
+	It analyzes the perf.data.old from the timestamp 3946.361400 to
+	the end of perf.data.old and analyzes the perf.data from the
+	timestamp 3971.150589 to the end of perf.data.
+
 COMPARISON
 ----------
 The comparison is governed by the baseline file. The baseline perf.data