Re: [patch] Cleaning up amd64 kernel optimization options
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On Fri, Dec 23, 2011 at 08:04:32PM +0100, Dimitry Andric wrote:
> On 2011-12-23 18:55, Kostik Belousov wrote:
> >On Fri, Dec 23, 2011 at 06:03:42PM +0100, Dimitry Andric wrote:
> ...
> >>The only thing my patch makes sure of, is that amd64 does the same thing
> >>as all other arches, e.g.: compile with a low optimization settings for
> >>debug (-O, which is equivalent to -O1), compile with arch-specific high
> >>optimization settings for release (-O2 plus whatever is required for the
> >>arch, or lower if optimization breaks things).
> >
> >Release is built with -g for long time, this is where the symbol files
> >in /boot/kernel comes from.
>=20
> Ah, that is done via 'makeoptions DEBUG=3D-g' in the kernel configuration
> file, right? I didn't realize that was kept in for a release. But even
> in that case, amd64 is somehow different from the other arches, which
> all get compiled with -O instead.
Yes.
>=20
> If people prefer that to stay as it is, I'll change the diff so only
> -frename-registers gets removed when clang is used, as clang does not
> support this flag.
This question cannot be answered without measurement. I think that even
the 'default' benchmark of buildworld over -O and -O2 kernels can be useful
to continue the discussion.
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