compositing enabled with Radeon mobility X300

Michel Dänzer michel at
Mon Aug 8 07:58:45 UTC 2016

On 06.08.2016 08:37, Jethro Tull wrote:
> From: Thomas Lübking [thomas.luebking at]
>> On Fri, Aug 05, 2016 at 09:24:01AM -0400, Alex Deucher wrote:
>>> How many displays are you using?  What resolution(s)?
> I mostly use only one monitor which is the LCD screen of the laptop I'm using
> which is has a resolution of 1280 x 800. Sometimes I connect an external LCD
> monitor set as extended desktop which resolution is 1440x900. But the problem
> with slow acceleration when compositing is enabled is on, either with or without
> the external monitor. On the other side, the refreshing of some windows I
> described were making the screens more or less scrambled after some time of
> work happens ONLY when the second monitor is on. I forgot to mention this last
> point in my original email.

Can you provide a screenshot showing the window refresh problem?

>> Finally, check the performance on low-resolution (XGA). The device is
>> short on RAM and compositing quite memory intense (notably in case of GL
>> compositing)
> Other resolutions than native give an ugly thing on LCD screens. My computer
> has 2 GB RAM, the video card is either 64 or 128 MB, and from what I can see in
> htop there is always plenty of free RAM available most of the time. I could
> nevertheless try low resolution just to see if compositing works better but I'm
> not sure that would mean I was short of RAM if the acceleration problem is
> partly or totally solved.

The potential issue is the VRAM on the card, which seems to be only
64MB, not the system RAM. You could try if

	Option "EXAPixmaps" "off"

in /etc/X11/xorg.conf helps. You could also try if current
xf86-video-ati Git master works better; there was recently a change
which reduced compositing overhead, but I'm afraid it's unlikely to make
a big difference with EXA.

Earthling Michel Dänzer               |     
Libre software enthusiast             |             Mesa and X developer

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