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Mail Archives: djgpp/1997/06/10/23:51:24

Message-ID: <c=US%a=_%p=Hassler_Communic%l=DAISY-970611034900Z-155@daisy.hcst.com>
From: Bryan Murphy <bryan DOT murphy AT hcst DOT com>
To: "'djgpp AT delorie DOT com'" <djgpp AT delorie DOT com>
Subject: Weird Results Tesitng Allegro's Performance
Date: Tue, 10 Jun 1997 23:49:00 -0400
MIME-Version: 1.0

I threw together a quick test tonight to figure out exactly
what kind of performance I could expect to get out of allegro
for my computer.  What I have is:

Cyrix 686 P150+ Chip
16meg 70ns Ram (not EDO)
82430HX Chipset

and most Importantly: Creative Labs 3D Blaster

Now, not expecting to be wowed at all by my 3D Blaster (which
I have full intentions on replacing soon, it sucks), I created
a test program to figure out the max number of blits I could
make each second.  I was shocked by the results.  Not at all
what I expected.  Here are the results under Windows 95:

Tested: 640,480 for 20 seconds

VGA Frames          = 53.9      - Expected slow, but not this slow
Vesa 1.0 Frames     = 133.6     - Believable
Vesa Banked Frames  = 155.4     - A little faster, expected this
Linear Frame Buffer = 114.1     - Whoa, did not expect this

Why is the linear frame buffer SLOWER than the banked?  Weird,
so I tried it a few more times (only one shown):

Tested: 640,480 for 20 seconds

VGA Frames          = 53.85
Vesa 1.0 Frames     = 143.25
Vesa Banked Frames  = 154.8
Linear Frame Buffer = 114.5

Yeah, it's definately slower. Very strange.  Anybody know what
can account for this?  I suppose it's just crappy design on the
part of Creative Labs.  I do also have the most recent bios on
the card.

Ok, none of this really has anything to do with DJGPP and Allegro.
So why am I posting this here?  Well, with the Vesa 2.0 Banked
Emulation mode, the bitmap was only blitting to the upper 20% of
the screen, and the rest remained blank.  Shawn, if you want me
to help you track down another bug, I can give it a shot.  I
suspect, however, once again that it's just crappy design on the
part of Creative Labs.  I'll try it with UniVBE when I get a chance
and report back if that fixes the problem.

- Raw text -


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