Commit d3439f9d authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

tracing: Document trace_marker triggers 



Add documentation and an example on how to use trace_marker triggers.

Reviewed-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Reviewed-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 3be4c1e5

Documentation/trace/events.rst

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@@ -338,10 +338,14 @@ used for conditionally invoking triggers. 


The syntax for event triggers is roughly based on the syntax for

set_ftrace_filter 'ftrace filter commands' (see the 'Filter commands'

section of Documentation/trace/ftrace.txt), but there are major

section of Documentation/trace/ftrace.rst), but there are major

differences and the implementation isn't currently tied to it in any

way, so beware about making generalizations between the two.



Note: Writing into trace_marker (See Documentation/trace/ftrace.rst)

     can also enable triggers that are written into

     /sys/kernel/tracing/events/ftrace/print/trigger



6.1 Expression syntax

---------------------

Documentation/trace/ftrace.rst

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@@ -507,6 +507,11 @@ of ftrace. Here is a list of some of the key files: 


		trace_fd = open("trace_marker", WR_ONLY);



	Note: Writing into the trace_marker file can also initiate triggers

	      that are written into /sys/kernel/tracing/events/ftrace/print/trigger

	      See "Event triggers" in Documentation/trace/events.rst and an

              example in Documentation/trace/histogram.rst (Section 3.)



  trace_marker_raw:



	This is similar to trace_marker above, but is meant for for binary data

Documentation/trace/histogram.txt

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