On Thursday 03 November 2005 09:47, Duncan wrote:
> So... certainly for kernel and probably for glibc stuff (tho I believe
> Gentoo kills -Os on glibc compiles unless you hack out that portion of the
> ebuild, in your own overlay or whatever), -Os is likely to be the best
> choice. For most of userland, -Os may be best, but to a smaller degree,
> and performance should be similar with -O2, trading size for medium speed
> optimizations in what amounts to a wash. The exceptions would likely be
> media encoders and the like, where the working set is large and in a data
> streaming environment, and -O3 may make sense. In the general case,
> however, -O3 likely does NOT make sense, because it's almost always so
> expensive in size that the gains in speed over -O2 are far outweighed.
AFAIR and so on.
Os is 'forbidden' for glibc, because there were some gcc bugs, that
miscompiled glibc with Os.
But with gentoo 1.2/1.4, I went for some time with Os in CFLAGS - and my
system was not faster than with O2. But it was a little faster with Os or O2
than O3 ;)
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