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Bug#697727: xserver-xorg-video-radeon: [radeon] Scrolling in xterm slow with KMS



On Thu, 10 Jan 2013 10:34:07 +0100, Michel Dänzer <daenzer@debian.org> wrote:

On Don, 2013-01-10 at 10:14 +0100, Tilo Schwarz wrote:
On Thu, 10 Jan 2013 09:16:37 +0100, Michel Dänzer <daenzer@debian.org>
wrote:

> On Mit, 2013-01-09 at 20:01 +0100, Tilo Schwarz wrote:
>>
>> Indeed, using
>>
>> % grep ColorTiling /etc/X11/xorg.conf
>>          Option          "ColorTiling"   "off"
>>
>> the scrolling is twice as fast as without this option (from 12sec down
>> to
>> 6sec). That is still almost three times slower than without KMS, but
>> already much more usable!
>
> The better solution would be to configure your terminals to use
> fontconfig/Xft for text rendering.

Do you have a link to "the correct debian way" to enable fontconfig/Xft
for text rendering? (Me being no X11 expert ...)

It's app/toolkit specific. E.g. with xterm you can enable it with -fa
and related options.


Is it a fontcontig and Xft, or is it a either fontcontig or Xft?

It's mainly about Xft. Most users of that also use fontconfig for
selecting the fonts to use, but that's not required.

Most apps/toolkits have used the modern text rendering infrastructure by
default for a long time, but a lot of terminal emulators are still
holding out for some reason.

Thanks a lot for your help! It lead me to a nice workaround (even if the original question KMS=0 vs. KMS=1 is not really solved by this).

The only thing I did (after reading about Xft and fontconfig) was to install rxvt-unicode, which has xft support.

Running "time seq 100000" with various terminal/font combinations gives:

xterm -fn 9x15:
real    0m50.001s
user    0m0.180s
sys     0m0.428s

xterm -fa 9x15:
real    0m7.785s
user    0m0.116s
sys     0m0.180s

rxvt:
real    0m11.707s
user    0m0.140s
sys     0m0.252s

urxvt:
real	0m0.994s
user	0m0.176s
sys	0m0.308s

So for some reason urxvt seems to use a font path, which is as fast as the speed having lenny installed. The Xresources for this test were:

% cat .Xresources
xterm*background: black
xterm*charClass: 33:48,37:48,45-47:48,38:48
xterm*font: 9x15
xterm*foreground: white
xterm*saveLines: 1024
xterm*scrollBar: false
xterm*visualBell: true
xterm*visualBellDelay: 100

rxvt*background: black
rxvt*charClass: 33:48,37:48,45-47:48,38:48
rxvt*font: 9x15
rxvt*foreground: white
rxvt*saveLines: 1024
rxvt*scrollBar: false
rxvt*visualBell: true
rxvt*visualBellDelay: 100

urxvt*background: black
urxvt*charClass: 33:48,37:48,45-47:48,38:48
urxvt*font: 9x15
urxvt*foreground: white
urxvt*saveLines: 1024
urxvt*scrollBar: false
urxvt*visualBell: true
urxvt*visualBellDelay: 100

Thanks again!

	Tilo


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