Merge tag 'trace-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...

[linux-2.6-microblaze.git] / Documentation / trace / ftrace.rst

diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index fdf5fb5..e45f078 100644 (file)
--- a/Documentation/trace/ftrace.rst
+++ b/Documentation/trace/ftrace.rst
@@ -543,6 +543,30 @@ of ftrace. Here is a list of some of the key files:
 
        See events.txt for more information.
 
+  timestamp_mode:
+
+       Certain tracers may change the timestamp mode used when
+       logging trace events into the event buffer.  Events with
+       different modes can coexist within a buffer but the mode in
+       effect when an event is logged determines which timestamp mode
+       is used for that event.  The default timestamp mode is
+       'delta'.
+
+       Usual timestamp modes for tracing:
+
+         # cat timestamp_mode
+         [delta] absolute
+
+         The timestamp mode with the square brackets around it is the
+         one in effect.
+
+         delta: Default timestamp mode - timestamp is a delta against
+                a per-buffer timestamp.
+
+         absolute: The timestamp is a full timestamp, not a delta
+                 against some other value.  As such it takes up more
+                 space and is less efficient.
+
   hwlat_detector:
 
        Directory for the Hardware Latency Detector.