Gentoo Archives: gentoo-amd64

From: "Hemmann
To: gentoo-amd64@l.g.o
Subject: Re: [gentoo-amd64] Old topic comes round again: -Ox optimizations.
Date: Thu, 03 Nov 2005 11:24:36
In Reply to: [gentoo-amd64] Old topic comes round again: -Ox optimizations. by Duncan <>
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 ;) -- gentoo-amd64@g.o mailing list


Subject Author
[gentoo-amd64] Re: Old topic comes round again: -Ox optimizations. Duncan <1i5t5.duncan@×××.net>