Re: [PATCH 0/11] LTTng-core (basic tracing infrastructure) 0.5.108

Roman Zippel
2006-09-15T21:28:25Z

Hi,

On Fri, 15 Sep 2006, Ingo Molnar wrote:

> > Nobody is taking dynamic tracing away!
> > You make it sound that tracing is only possible via dynamic traces.
> > If I want to use static tracepoints, why shouldn't I?
>
> because:
>
> - static tracepoints, once added, are very hard to remove - up until
> eternity. (On the other hand, markers for dynamic tracers are easily
> removed, either via making the dynamic tracer smarter, or by
> detaching the marker via the patch(1) method. In any case, if a
> marker goes away then hell does not break loose in dynamic tracing
> land - but it does in static tracing land.

This is simply not true, at the source level you can remove a static
tracepoint as easily as a dynamic tracepoint, the effect of the missing
trace information is the same either way.

> - the markers needed for dynamic tracing are different from the LTT
> static tracepoints.

What makes the requirements so different? I would actually think it
depends on the user independent of the tracing is done.

> - a marker for dynamic tracing has lower performance impact than a
> static tracepoint, on systems that are not being traced. (but which
> have the tracing infrastructure enabled otherwise)

Anyone using static tracing intents to use, which makes this point moot.

> - having static tracepoints dillutes the incentive for architectures to
> implement proper kprobes support.

Considering the level of work needed to support efficient dynamic tracing
it only withholds archs from tracing support for no good reason.

> > > > there are separate project teams is because managers in key
> > > > positions made the decision that they'd rather break from existing
> > > > projects which had had little success mainlining and instead use
> > > > their corporate bodyweight to pressure/seduce kernel developers
> > > > working for them into pushing their new great which-aboslutely-
> > > > has-nothing-to-do-with-this-ltt-crap-(no,no, we actually agree
> > > > with you kernel developers that this is crap, this is why we're
> > > > developing this new amazing thing). That's the truth plain and
> > > > simple.
> > >
> > > Stop whining!
> >
> > So we're back to personal attacks now. :-(
>
> hm, so you dont consider the above paragraph a whine. How would you
> characterize it then? A measured, balanced, on-topic technical comment?
> I'm truly curious.

It's sarcastic, but considering the disrespect towards Karim, I don't
blame him. At some point the "whining" argument was funny, but lately it's
only used to descredit people.

bye, Roman