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| author | Steffen Maier <maier@linux.ibm.com> | 2018-04-13 17:39:15 +0200 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2018-04-16 22:04:26 +0200 |
| commit | 32fb7ef69a9f1e3c8ec18a174fbc474b90ee645e (patch) | |
| tree | 91ed18270e5a3ca9d6609fbf814b13e4f06573b9 /Documentation/trace | |
| parent | Documentation/process: updates to the PGP guide (diff) | |
| download | linux-32fb7ef69a9f1e3c8ec18a174fbc474b90ee645e.tar.xz linux-32fb7ef69a9f1e3c8ec18a174fbc474b90ee645e.zip | |
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.rst | 7 |
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: |