Re: [patch for 2.6.26 0/7] Architecture Independent Markers

Frank Ch. Eigler
2008-03-28T15:33:54Z

Hi -

On Fri, Mar 28, 2008 at 03:41:16PM +0100, Ingo Molnar wrote:
> > > [...] furthermore, and because it's Friday again, let me remind
> > > folks that SystemTap has an even more significant bloat problem: the
> > > fact that it needs a huge download: [...the dwarf debugging
> > > information...]
> >
> > It's a problem, and there are a few improvements under way or being
> > contemplated: [...]
>
> it's been the primary usability problem ever since SystemTap has been
> incepted 3 years ago. [...]

This complaint is particularly rich, seeing how you constantly try to
shoot down patches that would reduce systemtap's need for this, such
as markers. And no, dyn-ftrace is not a complete substitute. See how
many of the markers in mathieu's lttng suite occur at places *other*
than function entry points. See how many require parameters other
than what may already sit in registers.

We in systemtap land have always had to make do with whatever was in
the kernel. There was very little other than kprobes 3 years ago. Of
newer facilities such as markers, ftrace, perfmon2 (I hope), and a
bunch of other little tracer thingies, all those that provide a usable
callback style interface can be exposed to systemtap. The more the
merrier, and the less we'd have to resort to the lowest-level
kprobes/dwarf stuff. Please help rather than obstruct.

- FChE