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@@ -155,6 +155,9 @@ of ftrace. Here is a list of some of the key files:
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to be traced. Echoing names of functions into this file
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will limit the trace to only those functions.
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+ This interface also allows for commands to be used. See the
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+ "Filter commands" section for more details.
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+
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set_ftrace_notrace:
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This has an effect opposite to that of
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@@ -1824,6 +1827,47 @@ this special filter via:
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echo > set_graph_function
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+Filter commands
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+---------------
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+
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+A few commands are supported by the set_ftrace_filter interface.
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+Trace commands have the following format:
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+
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+<function>:<command>:<parameter>
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+
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+The following commands are supported:
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+
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+- mod
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+ This command enables function filtering per module. The
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+ parameter defines the module. For example, if only the write*
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+ functions in the ext3 module are desired, run:
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+
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+ echo 'write*:mod:ext3' > set_ftrace_filter
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+
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+ This command interacts with the filter in the same way as
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+ filtering based on function names. Thus, adding more functions
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+ in a different module is accomplished by appending (>>) to the
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+ filter file. Remove specific module functions by prepending
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+ '!':
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+
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+ echo '!writeback*:mod:ext3' >> set_ftrace_filter
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+
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+- traceon/traceoff
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+ These commands turn tracing on and off when the specified
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+ functions are hit. The parameter determines how many times the
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+ tracing system is turned on and off. If unspecified, there is
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+ no limit. For example, to disable tracing when a schedule bug
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+ is hit the first 5 times, run:
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+
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+ echo '__schedule_bug:traceoff:5' > set_ftrace_filter
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+
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+ These commands are cumulative whether or not they are appended
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+ to set_ftrace_filter. To remove a command, prepend it by '!'
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+ and drop the parameter:
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+
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+ echo '!__schedule_bug:traceoff' > set_ftrace_filter
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+
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+
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trace_pipe
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----------
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