dri + ATI: dramatic performance slowdown

Oliver Lehmann lehmann at ans-netz.de
Mon Apr 27 05:18:36 UTC 2009

Hi Robert,

Robert Noland wrote:

> It still might be useful... Option "BusType" "PCI"

With "radeon" driver:

When xorg is started, my 2nd monitor keeps being black. The 1st one is
working. It looks like the hardware acceleration is not being used as
moving windows on the remaining monitor is really slow again. xrandr
lists the 2nd monitor. Switching to console and back does work - but the
2nd monitor remains black (no signal).
On Xorg Startup I get:

info: [drm] Setting GART location based on new memory map
error: [drm:pid728:r600_do_init_cp] *ERROR* Need gart offset from

in Xorg.log:
(II) RADEON(0): AGP card detected
(**) RADEON(0): Forced into PCI mode

pro: switching works
contra: no hardwareaccel., no dualhead

With "radeonhd" driver:

BusType seems to have no impact. The same behaviour like without.
Switching to console and back makes Xorg hang.

in Xorg.log
(II) RADEONHD(0): AGP Card Detected

Nothing about PCI mode.

pro: dualhead, hardwareaccel,
contra: no switching

Without the "busstype" Option, the radeon driver seems to be a bit more
performant for me because switching between my virtual desktops makes the
system hang for about 1-2 sec. with the radeonhd driver sometimes...

I've uploaded both Xorg.log files here:


 Oliver Lehmann

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