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tracing: Add documentation for trace commands mod, traceon/traceoff

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The mod command went in as commit
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The traceon/traceoff commands went in as commit
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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>
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Chase Douglas 2010-04-23 14:02:39 -04:00 committed by Steven Rostedt
parent a838b2e634
commit 07271aa42d
1 changed files with 44 additions and 0 deletions
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44
Documentation/trace/ftrace.txt
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@ -155,6 +155,9 @@ of ftrace. Here is a list of some of the key files:
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 @@ this special filter via:
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
----------