Documentation: ftrace: clarify filters with dynamic ftrace and graph

I fell into the trap of having set up function tracer with a very
limited filter and then switched over to function_graph and was
erroneously wondering why the latter did not trace what I expected,
which was the full unabridged graph recursion.

Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index e45f0786f3f9ef29bb1da2f9c2b3c8d7430adc85..9bbd3aefadb2e9e70f37cf090906fcabb82c6216 100644 (file)
--- a/Documentation/trace/ftrace.rst
+++ b/Documentation/trace/ftrace.rst
@@ -224,6 +224,8 @@ of ftrace. Here is a list of some of the key files:
        has a side effect of enabling or disabling specific functions
        to be traced. Echoing names of functions into this file
        will limit the trace to only those functions.
+       This influences the tracers "function" and "function_graph"
+       and thus also function profiling (see "function_profile_enabled").
 
        The functions listed in "available_filter_functions" are what
        can be written into this file.
@@ -265,6 +267,8 @@ of ftrace. Here is a list of some of the key files:
        Functions listed in this file will cause the function graph
        tracer to only trace these functions and the functions that
        they call. (See the section "dynamic ftrace" for more details).
+       Note, set_ftrace_filter and set_ftrace_notrace still affects
+       what functions are being traced.
 
   set_graph_notrace:
 
@@ -277,7 +281,8 @@ of ftrace. Here is a list of some of the key files:
 
        This lists the functions that ftrace has processed and can trace.
        These are the function names that you can pass to
-       "set_ftrace_filter" or "set_ftrace_notrace".
+       "set_ftrace_filter", "set_ftrace_notrace",
+       "set_graph_function", or "set_graph_notrace".
        (See the section "dynamic ftrace" below for more details.)
 
   dyn_ftrace_total_info: