Re: [PATCH v3 0/8] tracing/boot: Add new options for tracing specific period

From: Shuah Khan
Date: Thu Sep 10 2020 - 21:34:28 EST

On 9/10/20 7:27 PM, Masami Hiramatsu wrote:
On Thu, 10 Sep 2020 19:34:33 -0400
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

On Thu, 10 Sep 2020 17:54:54 +0900
Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:


Here is the 3rd version of the series to improve the boot-time tracing to
support kretprobe and tracing_on option. Previous version is here:

This version adds uprobe %return suffix support ([5/8]) and the testcases
([8/8]), and update kprobe %suffix support([4/8]) and the uprobe event

The combination of tracing_on and kretprobe allows us to trace events
while a specific function call period. For example, the below bootconfig
will make a function callgraph in the pci_proc_init() function at boot

ftrace {
tracing_on = 0 # off at start
tracer = function_graph
event.kprobes {
start_event {
probes = "pci_proc_init"
actions = "traceon"
end_event {
probes = "pci_proc_init%return"
actions = "traceoff"

Here is the example output;


Hi Masami,

This looks really great! I just got back from a 10 day holiday, and I'm
drowning in "catch-up". I plan on looking at all this relatively soon
(in a week or two?). I just don't want you to think I'm ignoring this.

Hi Steve,

Thanks, I hope you enjoyed the holiday!
BTW, this series includes some document update and testcases.
Since we can not decouple these updates, I think it is better you to
pull the series.

Hi Steve and Masami,

selftests patch 8/8 in this series looks good to me. My ack for
it to go through Steve's ftrace tree

Acked-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>

-- Shuah