Re: [PATCH 0/4] workqueue_tracepoint: Add worklet tracepoints for worklet lifecycle tracing

["Frank Ch. Eigler" <fche@redhat.com>]

Hi, Andrew -

On Tue, Apr 28, 2009 at 11:48:27AM -0700, Andrew Morton wrote:
> [...]
> > To be fair, if you ask for someone to specify and quantify the
> > "benefits" side of this, shouldn't someone specify and quantify the
> > "cost" side of this too?
> [...]
> >  That way we would have something to compare.
> 
> Well, there are two aspects to this.  There's the immediate up-front
> cost - a little added complexity, more code, etc.

Yes, a little.


> But there's also the where-the-hell-is-this-all-going question.  Are we
> going to end up with hundreds or thousands of tracepoints sprinkled all
> over core kernel?  If so, what use are they?  What userspace tools will
> be used to pull them into something useful?  Who will be developing
> those tools and are they involved in the development of the
> tracepoints?  

(Well, that's back to the "benefits" side, isn't it?)


> Will this proliferation of static tracepoints actively kill off the
> development and maturation of dynamic tracepoints?  If so, is that
> good?

I hope not, but I believe the consensus has been that both dynamic and
static instrumentation are necessary & useful.


> From where I sit it looks like a mad scramble to sprinkle fairly
> random tracepoints all over the place under the assumption that
> this-may-be-useful-to-someone-one-day.  But of course, that means
> that they many never be useful to anyone ever. [...]

You may not be giving enough credit to the subsystem developers.  If
they opine that those tracepoints may accomplish (or have already
accomplished) something forseeably useful, at a reasonably "little"
cost, should it not require a large burden of proof to overcome their
judgement?


- FChE