Re: [patch 0/4] perf_counter tools: support annotation of live kernel modules

Mike Galbraith
2009-07-03T08:01:12Z

On Fri, 2009-07-03 at 09:29 +0200, Ingo Molnar wrote:
> * Mike Galbraith <efault@gmx.de> wrote:
>
> > On Thu, 2009-07-02 at 09:17 +0200, Mike Galbraith wrote:
> >
> > > After I resurrect (well, try) live annotation in top...
> >
> > Random thought wrt live top annotation: instead of resurrecting in
> > the previous form, which could be a bit intrusive display space
> > wise, what do you think of this idea?
> >
> > Provide a kbd input snapshot trigger which builds a perf record
> > (hard?) compatible file for the symbols being displayed. Start a
> > background task to annotate the lot, stuffing annotate output into
> > an output file.
> >
> > Better ideas highly welcome.
>
> Hm, is there really a performance problem?

Sort of..

> We need to calculate and cache the objdump annotation output once,
> but after that it should be pretty fast as we just display updated
> counts with the same lines over and over again. No repeated objdump
> runs are needed.

But active files follow symbols, which change on the fly.

Besides, as mentioned previously, while displayed annotation was very
cool, it took a lot of display space. For me, top with the ability to
emit bic-disposable mini-reports would be my primary perf tools usage.
I'd only use big brothers when I needed their power/detail.

-Mike