ANDROID: trace: add non-hierarchical function_graph option
Add the 'funcgraph-flat' option to the function_graph tracer to use the default
trace printing format rather than the hierarchical formatting normally used.
Change-Id: If2900bfb86e6f8f51379f56da4f6fabafa630909
Signed-off-by: Jamie Gennis <jgennis@google.com>
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 185c39f..e20aacb 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -2102,6 +2102,35 @@
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.