Performance change from X in Fedora Core 4 to Fedora Core 5

Allen Akin akin at
Sat Jul 15 15:42:33 PDT 2006

On Sat, Jul 15, 2006 at 04:42:03PM +0900, Carsten Haitzler wrote:
| On Fri, 14 Jul 2006 23:32:41 -0700 Allen Akin <akin at> babbled:
| > The static allocation problem is fixable.  Overcommitting video ram is a
| > bigger problem, and compositing systems are naturally more likely to
| > suffer from it because they require unbounded amounts of memory.
| indeed they will be much more video ram hungry. it'd actually be nice to be
| able to query the location of a pixmap (or video vs agp vs system ram
| resources) and so possibly do smart things - like just free up excess pixmaps
| when resources get low.

Agreed, although to me, the most interesting question is what part of
the software stack has responsibility for doing the smart stuff.  As we
build things today, neither drivers, server, toolkits, nor apps have
enough information about the state of the whole system to know what to
do.  I think we will eventually want a component on the server side with
a global view (for lack of a better term, a scene graph; though it
wouldn't look exactly like scene graphs used by games or simulators).

| > That's true in today's Open Source desktop environments.  It wasn't true
| > in the old Iris GL days, for example, so it might not always be true in
| > the future.  Or in Vista and recent versions of OS X.
| sure - but how many "3d" apps will you have at once - windows with 3d views?
| not TOO many. i know where you are coming from - but i don't see things going
| to heavily 3d in the X world... any time soon... if ever.

Part of coming from the OpenGL world is that I don't believe there's
much real difference between 2D and 3D (and video, for that matter).  We
have a lot of historical reasons for having separate APIs, different
concepts of drawing surfaces, different models for color, etc., but
pretty much all of graphics boils down to transformations and
sampling[1], so in the end life will be better if we acknowledge that
and design more unified systems.

| a scene graph for the whole display - imho is the job of something like
| croquet and is out of the scope of what we were discussing :)

Maybe.  The fundamental questions (like resource management) come up
time after time, and I think one of the reasons is that the puzzle is
missing a piece.  We can work around the hole for a long time, but
eventually we'll want to go looking for that piece. :-)


[1] It's probably worth throwing in "perceptual psychology" here, too,
but so far there are only a few good examples (glyph hinting,
incremental display, color correction, etc.) that have made it into
mass-market systems.

More information about the xorg mailing list