Re: ftrace behaviour (was: [PATCH] ftrace: introducetracing_reset_online_cpus() helper)

From: Ingo Molnar
Date: Fri Dec 19 2008 - 17:57:39 EST



* Pekka Paalanen <pq@xxxxxx> wrote:

> > I'm actually against the idea of reseting a trace everytime we enable it.
> > That is:
> >
> > echo 1 > /debug/tracing/tracing_enabled
> >
> > This should not reset the tracer. I actually do tracing where I disable
> > and enable it around areas I am interested in. I want all tracing, not
> > just the last one.
>
> But doesn't this go against the fact, that you need to write 0 there to
> be able to change the ring buffer size?

hm, that ftrace behavior is silly. Steve, i think i mentioned this a long
time ago and i thought it got fixed? Changing the ring buffer size is a
slow op, it should include an implicit reset and should be plug-and-play
with no dependencies of having to stop the trace or something.

Ingo
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