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

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 Note, sched_switch and sched_wake_up will also trace events
listed in this file. 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_graph_function:
Set a "trigger" function where tracing should start Set a "trigger" function where tracing should start
@ -725,16 +730,14 @@ noraw
nohex nohex
nobin nobin
noblock noblock
nostacktrace
trace_printk trace_printk
noftrace_preempt
nobranch nobranch
annotate annotate
nouserstacktrace nouserstacktrace
nosym-userobj nosym-userobj
noprintk-msg-only noprintk-msg-only
context-info context-info
latency-format nolatency-format
sleep-time sleep-time
graph-time graph-time
record-cmd record-cmd
@ -742,7 +745,10 @@ overwrite
nodisable_on_free nodisable_on_free
irq-info irq-info
markers markers
noevent-fork
function-trace function-trace
nodisplay-graph
nostacktrace
To disable one of the options, echo in the option prepended with To disable one of the options, echo in the option prepended with
"no". "no".
@ -796,11 +802,6 @@ Here are the available options:
block - When set, reading trace_pipe will not block when polled. 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. trace_printk - Can disable trace_printk() from writing into the buffer.
branch - Enable branch tracing with the tracer. 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 When disabled, the trace_marker will error with EINVAL
on write. 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 function-trace - The latency tracers will enable function tracing
if this option is enabled (default it is). When 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 functions. This keeps the overhead of the tracer down
when performing latency tests. when performing latency tests.
Note: Some tracers have their own options. They only appear display-graph - When set, the latency tracers (irqsoff, wakeup, etc) will
when the tracer is active. 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.