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tracing: Add documentation on set_ftrace_notrace_pid and set_event_notrace_pid

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Update the tracing documentation to reflect the new files in the tracing
directory.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2020-03-26 13:22:44 -04:00
parent ebed9628f5
commit 2ab2a0924b
1 changed files with 31 additions and 0 deletions
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31
Documentation/trace/ftrace.rst
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@ -263,6 +263,20 @@ of ftrace. Here is a list of some of the key files:
traced by the function tracer as well. This option will also
cause PIDs of tasks that exit to be removed from the file.
set_ftrace_notrace_pid:
Have the function tracer ignore threads whose PID are listed in
this file.
If the "function-fork" option is set, then when a task whose
PID is listed in this file forks, the child's PID will
automatically be added to this file, and the child will not be
traced by the function tracer as well. This option will also
cause PIDs of tasks that exit to be removed from the file.
If a PID is in both this file and "set_ftrace_pid", then this
file takes precedence, and the thread will not be traced.
set_event_pid:
Have the events only trace a task with a PID listed in this file.
@ -274,6 +288,19 @@ of ftrace. Here is a list of some of the key files:
cause the PIDs of tasks to be removed from this file when the task
exits.
set_event_notrace_pid:
Have the events not trace a task with a PID listed in this file.
Note, sched_switch and sched_wakeup will trace threads not listed
in this file, even if a thread's PID is in the file if the
sched_switch or sched_wakeup events also trace a thread that should
be traced.
To have the PIDs of children of tasks with their PID in this file
added on fork, enable the "event-fork" option. That option will also
cause the PIDs of tasks to be removed from this file when the task
exits.
set_graph_function:
Functions listed in this file will cause the function graph
@ -1183,6 +1210,8 @@ Here are the available options:
tasks fork. Also, when tasks with PIDs in set_event_pid exit,
their PIDs will be removed from the file.
This affects PIDs listed in set_event_notrace_pid as well.
function-trace
The latency tracers will enable function tracing
if this option is enabled (default it is). When
@ -1197,6 +1226,8 @@ Here are the available options:
set_ftrace_pid exit, their PIDs will be removed from the
file.
This affects PIDs in set_ftrace_notrace_pid as well.
display-graph
When set, the latency tracers (irqsoff, wakeup, etc) will
use function graph tracing instead of function tracing.