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tracing: Update the documentation to describe "event-fork" option

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Add documentation to the ftrace.txt file in Documentation to describe the
event-fork option. Also add the missing "display-graph" option now that it
shows up in the trace_options file (from a previous commit).

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2016-04-19 10:24:38 -04:00 committed by Steven Rostedt
parent c37775d578
commit 540b589e63
1 changed files with 24 additions and 10 deletions
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34
Documentation/trace/ftrace.txt
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@ -210,6 +210,11 @@ of ftrace. Here is a list of some of the key files:
Note, sched_switch and sched_wake_up will also trace events
listed in this file.
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:
Set a "trigger" function where tracing should start
@ -725,16 +730,14 @@ noraw
nohex
nobin
noblock
nostacktrace
trace_printk
noftrace_preempt
nobranch
annotate
nouserstacktrace
nosym-userobj
noprintk-msg-only
context-info
latency-format
nolatency-format
sleep-time
graph-time
record-cmd
@ -742,7 +745,10 @@ overwrite
nodisable_on_free
irq-info
markers
noevent-fork
function-trace
nodisplay-graph
nostacktrace
To disable one of the options, echo in the option prepended with
"no".
@ -796,11 +802,6 @@ Here are the available options:
block - When set, reading trace_pipe will not block when polled.
stacktrace - This is one of the options that changes the trace
itself. When a trace is recorded, so is the stack
of functions. This allows for back traces of
trace sites.
trace_printk - Can disable trace_printk() from writing into the buffer.
branch - Enable branch tracing with the tracer.
@ -897,6 +898,10 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
When disabled, the trace_marker will error with EINVAL
on write.
event-fork - When set, tasks with PIDs listed in set_event_pid will have
the PIDs of their children added to set_event_pid when those
tasks fork. Also, when tasks with PIDs in set_event_pid exit,
their PIDs will be removed from the file.
function-trace - The latency tracers will enable function tracing
if this option is enabled (default it is). When
@ -904,8 +909,17 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
functions. This keeps the overhead of the tracer down
when performing latency tests.
Note: Some tracers have their own options. They only appear
when the tracer is active.
display-graph - When set, the latency tracers (irqsoff, wakeup, etc) will
use function graph tracing instead of function tracing.
stacktrace - This is one of the options that changes the trace
itself. When a trace is recorded, so is the stack
of functions. This allows for back traces of
trace sites.
Note: Some tracers have their own options. They only appear in this
file when the tracer is active. They always appear in the
options directory.