Re: Debug formats on Linux

[jfm2 at club-internet dot fr]

> On Sat, Oct 28, 2000 at 02:13:45AM +0200, jfm2@club-internet.fr wrote:
> 
> > I benchmarked -fomit-frame-pointer with gcc 2.95 and speed bonus was
> > well under 10%, and I think under 5%.  I found this funny since I
> > would expect an additional register woukld have a big impact on
> > register-starved x86s.  But unless omit-frame-pointer gives a far
> > bigger impact I would not want to go through yet another massive
> > change on Linux.  I have had enough with libc4 -> libc5 -> glibc plus
> > the uncompatible C++ libraries from
> >  gcc-2.7 -> egcs -> gcc-2.9[56]->gcc-3
> 
> fomit-frame-pointer gives better results to me, almost always around 
> 10%, notably with programs that are hard to speed up otherwise. That 
> is for x86 and m68k, 2.7.2.3, 2.8.[01], 2.95.*.
> 

What were the other parms?  My method was: start from "-O2)
-mcpu=pentiumpro" (later I redid it with "-O2 -march=pentiumpro" and
then successively apply every parm and look for the one giving the
bigger increase (inline-functions) and take the new flag set
(equivalent to -03 -mcpu=i686) as a new starting point.  The fact I
was optimizing for the P6 core instead of plain 386 and the fact I was
at O3 optimization level can have an influence.  I have noticed some
strange synergies during my tests: some parms have little or no effect
if some other parm is not present, in other occasions a parm who used
to have a positive effect has anegative effect if some other is
active.

This could explain the differences between our results.

-- 
			Jean Francois Martinez

Project Independence: Linux for the Masses
http://www.independence.seul.org