Flickering in graphics-heavy applications
1i5t5.duncan at cox.net
Wed Mar 31 14:23:37 BST 2010
Dotan Cohen posted on Wed, 31 Mar 2010 14:46:40 +0300 as excerpted:
> In KDE 4.4 with Composting enabled I get flickering in graphics-heavy
> applications such as Stellarium and Google Earth. I have an ATI video
> card and use the FOSS drivers as provided by my distro (Kubuntu). Is
> this a Kwin bug, or Stellarium/Google Earth bug? Video plays fine.
Which ATI card?
The Radeon r600/r700 series cards (most of the hdXXXX) are only now
getting proper OpenGL support in the stack, requiring pre-release mesa and
xf86-video-ati drivers, and strongly preferring a 2.6.33 kernel, so you'd
need to be running kubuntu 10.4-betas in ordered to get proper support
there and even they'd be pre-release upstream drivers. Evergreen (r800,
hd5xxx) will take a bit longer, at least another six months beyond that,
probably a year, as it just got 2D support merged, 3D/OpenGL isn't working
at all. It's very possible they'll go straight Gallium drivers for it.
The older r300-r500 drivers (generally the xXXXX series cards, with a few
exceptions at either end) are somewhat better, but of course, the hardware
is generally weaker, too. That'd probably depend on the resolution you're
running stuff. The ancient r100/r200 drivers have been well supported for
years, but the hardware is just not upto modern graphics demands, and
OpenGL breaks with resolutions above 2048 either direction.
And if you mean XRender instead of OpenGL based compositing, it works, but
is generally slower than OpenGL, so yeah, you're going to have artifacts.
Basically at this stage, you're best toggling off compositing when you're
doing heavy graphics. I /think/ it's supposed to turn it off when you run
a full-screen app on top of the stack anyway, but I never see it as I run
dual monitors and basically don't full-screen to both, only one, which
apparently doesn't turn off the compositing automatically, so if I want it
off I have to toggle it off.
The good news is that for r600/r700 series, what's currently upstream
(both kernel and x/mesa drivers) works quite well, so when it hits stable
release and the distribs pick it up for the fall release, things should
finally look quite good for semi-modern Radeon card users, tho not
Duncan - List replies preferred. No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master." Richard Stallman
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