tracing: Add documentation for trace commands mod, traceon/traceoff
The mod command went in as commit
64e7c440618998fd69eee6ab490b042d12248021
The traceon/traceoff commands went in as commit
23b4ff3aa479c9e3bb23cb6b2d0a97878399784a
Signed-off-by: Chase Douglas <chase.douglas@canonical.com>
LKML-Reference: <1272045759-32018-1-git-send-email-chase.douglas@canonical.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 5201181..557c1ed 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -155,6 +155,9 @@
to be traced. Echoing names of functions into this file
will limit the trace to only those functions.
+ This interface also allows for commands to be used. See the
+ "Filter commands" section for more details.
+
set_ftrace_notrace:
This has an effect opposite to that of
@@ -1824,6 +1827,47 @@
echo > set_graph_function
+Filter commands
+---------------
+
+A few commands are supported by the set_ftrace_filter interface.
+Trace commands have the following format:
+
+<function>:<command>:<parameter>
+
+The following commands are supported:
+
+- mod
+ This command enables function filtering per module. The
+ parameter defines the module. For example, if only the write*
+ functions in the ext3 module are desired, run:
+
+ echo 'write*:mod:ext3' > set_ftrace_filter
+
+ This command interacts with the filter in the same way as
+ filtering based on function names. Thus, adding more functions
+ in a different module is accomplished by appending (>>) to the
+ filter file. Remove specific module functions by prepending
+ '!':
+
+ echo '!writeback*:mod:ext3' >> set_ftrace_filter
+
+- traceon/traceoff
+ These commands turn tracing on and off when the specified
+ functions are hit. The parameter determines how many times the
+ tracing system is turned on and off. If unspecified, there is
+ no limit. For example, to disable tracing when a schedule bug
+ is hit the first 5 times, run:
+
+ echo '__schedule_bug:traceoff:5' > set_ftrace_filter
+
+ These commands are cumulative whether or not they are appended
+ to set_ftrace_filter. To remove a command, prepend it by '!'
+ and drop the parameter:
+
+ echo '!__schedule_bug:traceoff' > set_ftrace_filter
+
+
trace_pipe
----------
