Re: [patch 00/2] improve .text size on gcc 4.0 and newer compilers

Ingo Molnar
2005-12-31T14:46:06Z

* Adrian Bunk <bunk@stusta.de> wrote:

> On Fri, Dec 30, 2005 at 08:49:16AM +0100, Ingo Molnar wrote:
> >
> > * Tim Schmielau <tim@physik3.uni-rostock.de> wrote:
> >
> > > What about the previous suggestion to remove inline from *all* static
> > > inline functions in .c files?
> >
> > i think this is a way too static approach. Why go from one extreme to
> > the other, when my 3 simple patches (which arguably create a more
> > flexible scenario) gives us savings of 7.7%?
>
> This point only discusses the inline change, which were (without
> unit-at-a-time) in your measurements 2.9%.
>
> Your patch might be simple, but it also might have side effects in
> cases where we _really_ want the code forced to be inlined. How simple
> is it to prove that your uninline patch doesn't cause a subtle
> breakage somewhere?

it's quite simple: run the latency tracer with stack-trace debugging
enabled, and it will measure the worst-case stack footprint that is
triggered on that system. Obviously any compiler version change or
option change can cause problems, there's nothing new about it - and
it's not realistic to wait one year for changes like that. If you have
to wait that long, you are testing it the wrong way.

Ingo