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List Archive: gentoo-amd64
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To: gentoo-amd64@g.o
From: "Hemmann, Volker Armin" <volker.armin.hemmann@...>
Subject: Re: Old topic comes round again: -Ox optimizations.
Date: Thu, 3 Nov 2005 12:22:03 +0100
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


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Re: Old topic comes round again: -Ox optimizations.
-- Duncan
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Old topic comes round again: -Ox optimizations.
-- Duncan
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Updated Jun 17, 2009

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