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::