Commit 627645fd authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt

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
...@@ -288,6 +288,24 @@ prev_pid == 0 ...@@ -288,6 +288,24 @@ prev_pid == 0
# cat sched_wakeup/filter # cat sched_wakeup/filter
common_pid == 0 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 6. Event triggers
================= =================
......
...@@ -204,6 +204,12 @@ of ftrace. Here is a list of some of the key files: ...@@ -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. 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_graph_function:
Set a "trigger" function where tracing should start Set a "trigger" function where tracing should start
......
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