Date: Sat, 24 Jun 2006 00:21:53 -0500 From: "Nikolas Britton" <nikolas.britton@gmail.com> To: freebsd-questions@freebsd.org Subject: Re: migrating to 64-bit Message-ID: <ef10de9a0606232221i77605b4fla7682c953d8fc7cd@mail.gmail.com> In-Reply-To: <20060624014452.GT11625@tigger.digitaltorque.ca> References: <20060620233551.GG11625@tigger.digitaltorque.ca> <Pine.SOL.4.53.0606201958420.14129@brak> <20060621011340.GI11625@tigger.digitaltorque.ca> <ef10de9a0606210342y67ff7c61le018aa6ffdd48313@mail.gmail.com> <20060621173253.GD7596@tigger.digitaltorque.ca> <ef10de9a0606211152o3be3e502y91264ed01ed39fe@mail.gmail.com> <20060624014452.GT11625@tigger.digitaltorque.ca>
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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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