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Date: Sat, 24 Jun 2006 00:21:53 -0500
From: "Nikolas Britton" <nikolas.britton@gmail.com>
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Subject: Re: migrating to 64-bit
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On 6/23/06, Michael P. Soulier <msoulier@digitaltorque.ca> wrote:
> On 21/06/06 Nikolas Britton said:
>
> > The consensus seems to be that FreeBSD/amd64 is a tad slower then
> > FreeBSD/i386 because it has to deal with 32 extra bits. The primary
> > reason to use FreeBSD/amd64 seems to be if you need greater then 4GB
> > of RAM.
> >
> > This should give you the speed boost your looking for:
> > CPUTYPE?=pentium2
> > CFLAGS+= -mtune=nocona
> > COPTFLAGS+= -mtune=nocona
> >
> > Put that in /etc/make.conf and recompile ports/kern/world.
>
> Cool, thanks.
>
> Mike
>

Yea it looks weird but I've benchmarked it:

-march=pentium2 + -mtune=pentium3
-march=pentium2 + -mtune=pentium4
-march=pentium2 + -mtune=prescott
-march=pentium2 + -mtune=nocona

All are equal to or better then -march={your_real_cpu} alone, which is
weird because -march=cputype implies -mtune=cputype. My gcc settings
also produce safer (less buggy) code at compile time and safely
optimizes code that would otherwise ignore the CPUTYPE option in
make.conf... YMMV.


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