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

[Steven Rostedt]

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

> Hi,
> 
> 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:
> 
>  https://lkml.kernel.org/r/159894698993.1478826.2813843560314595660.stgit@devnote2
> 
> 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
> document([6/8]).
> 
> 
> 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
> time.
> 
> 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.

-- Steve