Re: [9fans] hardware acceleration

[nigel@9fs.org]

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In support of this, it would seem that the access the vga chip
affords to memory through the bus is inversely proportional
to the speed at which it can bitblt itself.

In other words, the more the chip does for you, the less the
designers feel the need to put in decent bus access.

What really ought to limit it is the priority access the playout
has. So, it you want to speed up your vga i/o, perhaps turning
down the refresh rate is the answer. Somehow I doubt it.


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From: "Russ Cox" <rsc@plan9.bell-labs.com>
To: 9fans@cse.psu.edu
Subject: [9fans] hardware acceleration
Date: Tue, 13 Feb 2001 19:45:01 -0500
Message-ID: <20010214004507.48578199D5@mail.cse.psu.edu>

To address that, in 8bpp it's really not too much
of an issue, but for higher modes the system is mostly
unusable without scrolling and filling.  It's not
a question of the efficiency of the code (i.e., having
a JIT wouldn't help).  The problem is the readback speed
on the VGA card, which nails you when you're doing
software scrolling.  I can read from my 5400rpm disk
faster than I can read from my VGA memory.

Russ