Re: [PATCH] ftrace: Add a C-state tracer to help power optimization

From: Ingo Molnar
Date: Sat Oct 04 2008 - 04:32:58 EST



* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

>
> On Fri, 3 Oct 2008, Arjan van de Ven wrote:
>
> > On Fri, 3 Oct 2008 20:32:51 -0400 (EDT)
> > Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> >
> > >
> > > Hi Arjan,
> > >
> > > Very nice! I just have a few comments below.
> >
> > since this is my first tracer.... I would suggest having a "golden
> > example" one that people can copy (it seems I copied a less than
> > perfect one ;-)... maybe a trace_example.c ?
>
> Yeah, that would make sense to have. People are starting to come
> up with so many different tracers, I'm not sure what a golden
> example would look like :-/

i think starting with kernel/trace/trace_nop.c is the simplest: copy
that into a new plugin and make it show up in make oldconfig and make it
build. Then add ftrace_printk() lines initially - only specialize the
trace entries to that plugin later on.

Ingo
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