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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2016-04-19 17:24:38 +0300
committerSteven Rostedt <rostedt@goodmis.org>2016-04-19 17:28:29 +0300
commit540b589e6349779c0eeb8de82450b62a4569ffd9 (patch)
tree9731fc40bf9c8ab60b9bfa77173bef7f52c251f6 /Documentation/trace
parentc37775d57830a36382a9774bb84eca4ce3d019cc (diff)
downloadlinux-540b589e6349779c0eeb8de82450b62a4569ffd9.tar.xz
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>
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/ftrace.txt34
1 files changed, 24 insertions, 10 deletions
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index f52f297cb406..fdf18485db2b 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -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.