On 8/22/06, Timothy Miller <[EMAIL PROTECTED]> wrote:
On 8/21/06, Jon Smirl <[EMAIL PROTECTED]> wrote:
> You might want to poll your consumers and see if they are going to buy
> a PCI board. I only use PCI versions of cards for test and
> development. They are visibly too slow for normal use.
Unless you accelerate enough stuff so that it's not visibly slow.
Cards are only visibly slow under Linux because the drivers are half
done. Some don't accelerate a lot more than bitblt and solid fill (it
would seem), so text, lines, patterned fills, and numerous other
things are slow and you can tell. Even image loads are perceptibly
faster when you use DMA (more efficient use of the bus).
My 2000-era TROZ design is something you would never know was on a PCI
bus. That's partly because my DDX accelerates everything. Tiles,
stipples, text (with a number of special cases for more performance),
solid fills, bitblts, lines, complex shapes (via accelerated spans,
solid, stippled, and tiled), and a number of other things you would
never consider accelerating because they're useful for ATC and give
your system a more responsive feel. I even accelerate zeropolyarcs!
You would be surprised how much more responsive your system feels when
the default X11 root window tile is accelerated.
TROZ even has a mechanism to apply a planemask and a ROP to host
writes to the framebuffer, so rather than a read-modify-write cycle,
it's just a write, making something like a putimage with XOR several
times faster than it would otherwise be.
The higher layers in X only make significant use of fill and bitblt.
That is why line drawing was dropped from EXA. Most of the functions
in an XAA driver are hardly ever used. Text is drawn with bitblt. What
is used heavily now with render is alpha channel bitblt with per plane
drawing (LCD text).
Text is generated in system RAM and then bitblted into place. Straight
lines can be drawn with the fill hardware. The apps have stopped
using line drawing since they want to alpha blend (antialias) the
edges.
--
Jon Smirl
[EMAIL PROTECTED]
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