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Commit 627645fd authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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tracing: Add some documentation about set_event_pid 



Update Documentation to include some comments about how to use
set_event_pid.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 54ed1444

Documentation/trace/events.txt

+18 −0
Original line number Diff line number Diff line
@@ -288,6 +288,24 @@ prev_pid == 0 
# cat sched_wakeup/filter

common_pid == 0



5.4 PID filtering

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



The set_event_pid file in the same directory as the top events directory

exists, will filter all events from tracing any task that does not have the

PID listed in the set_event_pid file.



# cd /sys/kernel/debug/tracing

# echo $$ > set_event_pid

# echo 1 > events/enabled



Will only trace events for the current task.



To add more PIDs without losing the PIDs already included, use '>>'.



# echo 123 244 1 >> set_event_pid





6. Event triggers

=================

Documentation/trace/ftrace.txt

+6 −0
Original line number Diff line number Diff line
@@ -204,6 +204,12 @@ of ftrace. Here is a list of some of the key files: 


	Have the function tracer only trace a single thread.



  set_event_pid:



	Have the events only trace a task with a PID listed in this file.

	Note, sched_switch and sched_wake_up will also trace events

	listed in this file.



  set_graph_function:



	Set a "trigger" function where tracing should start