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authorSteffen Maier <maier@linux.ibm.com>2018-04-13 18:39:15 +0300
committerJonathan Corbet <corbet@lwn.net>2018-04-16 23:04:26 +0300
commit32fb7ef69a9f1e3c8ec18a174fbc474b90ee645e (patch)
tree91ed18270e5a3ca9d6609fbf814b13e4f06573b9 /Documentation/trace
parent1ba2211c525a205caed76adc6a328b423556f6e5 (diff)
downloadlinux-32fb7ef69a9f1e3c8ec18a174fbc474b90ee645e.tar.xz
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>
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/ftrace.rst7
1 files changed, 6 insertions, 1 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index e45f0786f3f9..9bbd3aefadb2 100644
--- 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: