Date: Tue, 14 Mar 2000 13:33:47 +0100 (CET) From: Oliver Fromme <olli@dorifer.heim3.tu-clausthal.de> To: freebsd-multimedia@FreeBSD.ORG, vallo@matti.ee Subject: Re: gogo + 3dnow Message-ID: <200003141233.NAA70280@dorifer.heim3.tu-clausthal.de> In-Reply-To: <8ala1u$1cmj$1@atlantis.rz.tu-clausthal.de>
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Vallo Kallaste <vallo@matti.ee> wrote in list.freebsd-multimedia:
> As I understand the PIII SSE instructions have no use at the moment.
> What are the reasons FreeBSD doesn't support SSE? Is it hard work to do
> or mostly missing developer time?
What do you mean by saying "FreeBSD doesn't support" it?
FreeBSD doesn't "support" 3DNow either, but that doesn't
prevent anyone from writing programs that run under FreeBSD
and use 3DNow instructions. In fact, I already did that.
If you mean that FreeBSD's compiler (gcc) should automatically
create SSE (or MMX, or 3DNow) instructions from standard code,
well, that's a different issue. And it's very non-trivial to
_automatically_ identify code sections that could be improved
using SSE (or ...) instructions. In particular, you cannot
use FPU instructions at the same time, and switching between
those instruction sets involves a certain delay penalty.
Therefore I think it is _much_ more useful to improve critical
code sections _manually_ by replacing them with SSE (...) code
if appropriate. This can result in _dramatic_ performance
improvements (+100% and more). This is not just theory -- I
experimented a lot with 3DNow in the past months.
BTW: I also have some patches to nasm to support the new
instructions (enhanced K7 3DNow / SSE) and submitted them to
the nasm author in Autumn last year. He replied that he
already had patches himself and would release them along with
a new version. I haven't heard anything since then, but I
haven't actively looked for it.
Regards
Oliver
--
Oliver Fromme, Leibnizstr. 18/61, 38678 Clausthal, Germany
(Info: finger userinfo:olli@dorifer.heim3.tu-clausthal.de)
"In jedem Stück Kohle wartet ein Diamant auf seine Geburt"
(Terry Pratchett)
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