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Date:      Tue, 8 Nov 2005 11:31:56 +0300
From:      "Andrew P." <infofarmer@gmail.com>
To:        Chuck Swiger <cswiger@mac.com>
Cc:        freebsd-stable@freebsd.org, Craig Boston <craig@feniz.gank.org>
Subject:   Re: 5.x, 6.x and CPUTYPE
Message-ID:  <cb5206420511080031k40510a70g10f6c8b32f497a0e@mail.gmail.com>
In-Reply-To: <4370225D.2070201@mac.com>
References:  <20051107151050.GA1212@nowhere> <200511080205.jA825Dbl046080@app.auscert.org.au> <20051108032328.GA3544@nowhere> <4370225D.2070201@mac.com>

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On 11/8/05, Chuck Swiger <cswiger@mac.com> wrote:
> Craig Boston wrote:
> > On Tue, Nov 08, 2005 at 12:05:13PM +1000, Joel Hatton wrote:
> >> Thanks, Craig. I'm glad to hear that I'm not alone in pursuing this me=
thod.
> >> Do you know of any particular disadvantages of continuing with this
> >> less-than-optimised model - I guess I mean, is this something that is
> >> likely to break or become uneconomical at some point?
> >
> > It won't break; after all the release binaries are targeted for 386 (or
> > maybe 486 now) in order to be able to run on anything.  You might need
> > to update make.conf with the "pentiumpro" name just in case they ever
> > drop the i686 alias, but that's about it.
>

Remeber that MacOSX/i386 requires the latest SSE feature
set? Well, some day, although in a much more justified way,
that might happen to FreeBSD. I don't think it'll happen earlier
than 5-10 years from now, but it will. It doesn't mean you'll
have to put something in your configs - just that the default
target will include optimizations for some instructions.

I still don't understand many of this gcc scheduling stuff, but
-mfpmath=3Dsse should give a noticable boost to all code,
not matter when it was written. Also, things like OpenSSH
and mplayer were manually optimized to benefit from MMX,
MMX2, 3DNow, 3DNowEx, SSE, SSE2... (that's what
mplayer says about my athlon64 cpu, it was compiled
without runtime cpu detection).

So that's a matter of taste. It's not in vain to have a dozen
scheduling configurations for a medium site, but it could
live without that. Personally, I think, if there's a way to
automate everything nicely, then one should do it. Package
building is another issue, but I think FreeBSD will gain a
good world-wide distributed compilation network, where
you can get a binary with some specific options and
optimizations, - in the months to come. Let's hope for that.



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