lkml.org 
[lkml]   [2020]   [Sep]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 6/6] Documentation: tracing: boot: Add an example of tracing function-calls
Date
Add an example of tracing function calls on a specific function.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
Documentation/trace/boottime-trace.rst | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/Documentation/trace/boottime-trace.rst b/Documentation/trace/boottime-trace.rst
index 1341b449acaa..c216f5695ae2 100644
--- a/Documentation/trace/boottime-trace.rst
+++ b/Documentation/trace/boottime-trace.rst
@@ -168,6 +168,26 @@ is for tracing functions starting with "user\_", and others tracing
The instance node also accepts event nodes so that each instance
can customize its event tracing.

+With the trigger action and kprobes, you can trace function-graph while
+a function is called. For example, this will trace all function calls in
+the pci_proc_init()::
+
+ ftrace {
+ tracing_on = 0
+ tracer = function_graph
+ event.kprobes {
+ start_event {
+ probes = "pci_proc_init"
+ actions = "traceon"
+ }
+ end_event {
+ probes = "pci_proc_init%return"
+ actions = "traceoff"
+ }
+ }
+ }
+
+
This boot-time tracing also supports ftrace kernel parameters via boot
config.
For example, following kernel parameters::
\
 
 \ /
  Last update: 2020-09-01 09:58    [W:0.195 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site