Slow 2D with radeon KMS

Damien Mir mailings.xorg at
Fri Feb 12 05:58:01 PST 2010

Now with :
- xserver 1.7.4
- 2.6.33rc7 with KMS
- libdrm, mesa, xf86-video-ati from git
2D and 3D are back OK on an R700 (HD4650 mobility (M98))

However I see 2 performance issues :
- glxgears tops at 1450fps (compared to ~2500fps without KMS)
- GL vsync is broken, ie visual tearing especially at playing large videos
(XV or OGL) with Kwin compositing enabled

Any thoughts on this ?

> On Sat, 30 Jan 2010 15:35:44 +0100 (CET)
> "Damien Mir" <mailings.xorg at> wrote:
>> Hi,
>> I just tried KMS with "radeon" driver, and 2D seems notably slow.
>> Widgets takes time to draw, scrolling in Dolphin or Firefox lags, as
>> if some 2D acceleration was not working alright.
> I use radeon KMS on an R600 (HD 3870) and all works really well. 2D as
> well as 3D (glxgear, tuxracer, nexuiz). Kernel is 2.6.32 and
> drm, mesa, xf86-video-ati are latest git HEAD. Maybe you need a newer
> version of the ati driver.
> harry
> _______________________________________________
> xorg mailing list
> xorg at

More information about the xorg mailing list