From: D DOT J DOT Eleveld AT anest DOT azg DOT nl
Newsgroups: comp.os.msdos.djgpp
Subject: Re: How safe is the -march=pentium flag?
Date: Mon, 10 Aug 1998 19:19:58 GMT
Organization: Deja News - The Leader in Internet Discussion
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In article <Pine DOT SUN DOT 3 DOT 91 DOT 980810164925 DOT 4349A-100000 AT is>,
  Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> wrote:
>
> On Mon, 10 Aug 1998 D DOT J DOT Eleveld AT anest DOT azg DOT nl wrote:
>
> > I've just been playing with the -march flags and found a huge speed increase
> > when I used -march=pentuim.
>
> How huge is ``huge''?  Can you give some numbers?

Ok, I was playing with optimizing the inner loops of the AllegPeg Mpeg player
library for Allegro.  I do my profiling stuff with some pentium-specific code
that counts clock cycles.  With -march=pentium I get 27.7M clock cycles per
frame with my Pentiun 133 with painfully slow (banked) video card.  Exactly
the same flags and code (just changed the compiler options in Rhide, and
rebuilt) gets me 32.6M clock cycles per frame. There are quite a few small
loops there so memory alignment will probably be crucial.

Is this expected, or maybe semi-normal?

Thanks,

Doug Eleveld

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