Messages in this thread | | | Date | Mon, 17 Jun 2019 20:16:27 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] ftrace: add simple oneshot function tracer |
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On Wed, 12 Jun 2019 23:29:35 +0200 Thomas Preisner <linux@tpreisner.de> wrote:
Hi Thomas,
BTW, what email client do you use, because your replies seem to confuse my email client (claws-mail) and it doesn't thread them at all. Although they do look fine on mutt (when I view my LKML folder). Looks like it doesn't create a "References:" header.
> On Tue, 11 Jun 2019 17:52:37 -0400 > Steven Rostedt <rostedt@goodmis.org> wrote: > > > What do you mean? The function profile has its own file to enable it: > > > > echo 1 > /sys/kernel/tracing/function_profile_enabled > > > > And disable it: > > > > echo 0 > /sys/kernel/tracing/function_profile_enabled > > > > -- Steve > > Yes, I am aware of the function profiler providing a file operation for > enabling and disabling itself. However, my oneshot profiler as of [PATCH > v2] is a separate tracer/profiler without this file operation. > > As this oneshot profiler is intended to be used for coverage/usage > reports I want it to be able to record functions as soon as possible > during bootup. Therefore, I just permanently activated the oneshot > profiler since as of now there is no means to activate it or the > function profiler via kernel commandline just like the normal tracers. > > Still, if you want to I can add the file operation for > enabling/disabling this new profiler together with a new kernel > commandline argument for this profiler? > > Or what would be your prefered way? >
Hmm, I guess I still need to think about exactly what this is for. Perhaps we could add a "oneshot" option to the function tracer, and when set it will only trace a function once? Is there a strong reason to add a new event type "oneshot_entry"? It may be useful to record the parent of the function that triggered the first instance as well.
I'm still trying to get a grip around exactly what use cases this would be good for. Especially when adding new functionality like this.
-- Steve
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