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diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index bfe8c29b1f1d..29064c3bfcd1 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -2013,6 +2013,35 @@ will produce:
1) 1.449 us | }
+You can disable the hierarchical function call formatting and instead print a
+flat list of function entry and return events. This uses the format described
+in the Output Formatting section and respects all the trace options that
+control that formatting. Hierarchical formatting is the default.
+
+ hierachical: echo nofuncgraph-flat > trace_options
+ flat: echo funcgraph-flat > trace_options
+
+ ie:
+
+ # tracer: function_graph
+ #
+ # entries-in-buffer/entries-written: 68355/68355 #P:2
+ #
+ # _-----=> irqs-off
+ # / _----=> need-resched
+ # | / _---=> hardirq/softirq
+ # || / _--=> preempt-depth
+ # ||| / delay
+ # TASK-PID CPU# |||| TIMESTAMP FUNCTION
+ # | | | |||| | |
+ sh-1806 [001] d... 198.843443: graph_ent: func=_raw_spin_lock
+ sh-1806 [001] d... 198.843445: graph_ent: func=__raw_spin_lock
+ sh-1806 [001] d..1 198.843447: graph_ret: func=__raw_spin_lock
+ sh-1806 [001] d..1 198.843449: graph_ret: func=_raw_spin_lock
+ sh-1806 [001] d..1 198.843451: graph_ent: func=_raw_spin_unlock_irqrestore
+ sh-1806 [001] d... 198.843453: graph_ret: func=_raw_spin_unlock_irqrestore
+
+
You might find other useful features for this tracer in the
following "dynamic ftrace" section such as tracing only specific
functions or tasks.