Very slow graphics operations + errors while redrawing

Michal Rybárik michal at
Sun Apr 12 11:22:35 PDT 2015

Hello everybody,

I have installed Centos 6.6 on embedded PC with 1 GHz i686 CPU, 1 GB RAM 
and Radeon R200 dualhead card. I am using opensource radeon driver 
7.3.99. I am facing the problems, that some very trivial graphics 
operations are extemely slow, and I cannot find where is the problem. 
Problem applies to both KDE and GNOME. On the exacly the same machine, I 
was using OpenSUSE 11.3 some time ago (with older radeon drivers, older 
Xorg, older kernel, etc), and ooffice and also rdesktop were woking very 
nice and very fast, there wasn't any performance issue with these 
graphics operations, and I also haven't notice any redraw issues.

Now If I start openoffice (libreoffice) calc, select few cells, and 
press Ctrl-C (copy), dashed border is drawn around selected area, and 
dashes are moving around. Xorg process starts to eat 100% CPU and load 
is coming higher and higher, and machine starts to be unresponsive. If I 
deselect cells and moving dashed border disappears, load come back to 
normal. If I select less cells and dashed border is smaller, machine 
load is smaller too.

If I start rdesktop connection to Windows machine on local gigabit 
network, and I log in, I can see that Windows desktop and running 
applications are drawn on my local screen element by element, and it 
tooks ~20 seconds to draw whole remote screen. Working on remote 
computer is almost unpossible, even on local gigabit network. Rdesktop 
process takes 0.3% CPU meantime, and Xorg process takes around 10-20% 
CPU. With newer xfreerdp app it is exacly the same.

When I run glxgears, it works nicely, also when maximized. With vsync I 
have 60 fps (same as LCD frequency), without vsync I have around 290 fps 
(which is OK I think, because this is quite slow machine with PCI VGA 
card). No problem at all with glxgears, which is IMHO more complex to 
display, than simple dashed border in OOcalc.

I also noticed that in Firefox (and also some other apps) when I scroll 
text, some portions of the scrolled area are not redrawn correctly. Some 
lines or parts of lines are not displayed at all, or they are displayed 
twice (= part of the window is redrawn, while other part remains unchanged).

How can I find what's wrong with this, and how to repair it?

Many thanks

Michal Rybarik

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