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XRender compositing faster than OpenGL?

User avatar the_mouse
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Hey guys, I'm using Kubuntu 10.04 32bit with KDE 4.4.2 and running desktop effects with OpenGL mode is for some reason too slow.

My graphics card is NVIDIA GeForce 9500GT and my CPU is Athlon 3000+ @2GHz. I have 1GB RAM installed on my system.

Up until recently I thought that my single-core CPU (with on-board graphics card) is the problem, so I bought a newer graphics card only to find out that KWin's performance is still quite slow.

My NVIDIA driver version is 195.36.24.

Here's a part of my xorg.conf:

Code: Select all
Section "Device"
   Identifier   "Default Device"
   Driver   "nvidia"
   Option   "NoLogo"   "True"
        Option         "RenderAccel" "true"
Option        "AllowGLXWithComposite" "true"
EndSection

Section "Extensions"
  Option "Composite" "Enable"
EndSection


Today I decided to give a try the XRender mode in KWin's settings and there's definetly some improvement in terms of speed! Desktop effects seem to run faster on XRender, but doesn't that mean that there's something wrong with my KWin/OpenGL/xorg.conf/NVIDIA configuration? Isn't XRender supposed to be much slower than OpenGL?

Anyway, I would really want to utilize my graphics card to do the desktop effects processing, so I think OpenGL would be a better option. So, do you guys have any idea on how to increase my KWin OpenGL performance?

ps.: other OpenGL applications seem to work pretty well (tux racer for example)

Last edited by the_mouse on Sat Sep 18, 2010 9:37 am, edited 1 time in total.
droetker
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Can definitely confirm this on Kubuntu 10.04 amd64 with nvidia graphics.
OpenGL is sluggish, XRender is fast, but is not able to draw some plugins (Cover switch is disabled then e.g.)
Shining Arcanine
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droetker wrote:Can definitely confirm this on Kubuntu 10.04 amd64 with nvidia graphics.
OpenGL is sluggish, XRender is fast, but is not able to draw some plugins (Cover switch is disabled then e.g.)


I can confirm this on Gentoo Linux ~amd64 with the Nvidia 256.44 drivers. I have a Nvidia GTS 250 graphics card and OpenGL is sluggish while XRender is relatively faster. If I play an online game called Runescape with compositing on, everything lags. If I have XRender configured, the lag is not as bad.
mgraesslin
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XRender does not require TextureFromPixmap and is therefore faster for initial mapping of windows in the case of NVIDIA. This includes e.g. resizing, (un)minimizing and opening of new windows. With other drivers it's faster. Furthermore OpenGL is faster for everything else and looks much better.
OlivierToupin
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Anyway to make it faster on Nvidia hardware?

Also can you more precise what's wrong with TextureFromPixmap on Nvidia hardware?

--

Arch Linux x64
Asus G1s
Intel Core 2 Duo T7500
Nvidia GeForce 8600M GT, 256 MB
mgraesslin
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OlivierToupin wrote:Anyway to make it faster on Nvidia hardware?

There are some things for initial pixmap creation strategy. But I have no idea how. Just google for it, preferable in bugs.kde.org ;-)

OlivierToupin wrote:Also can you more precise what's wrong with TextureFromPixmap on Nvidia hardware?

As said: the initial pixmap binding is slow. So whenever a new TFP process is required that is slow. That includes everything where a window appears or is changed in its size.
OlivierToupin
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I changed to "OpenGL mode: Shared Memory" in the Desktop Effects applet. I much faster now.

I don't know if there is any disadvantage of using it over pixmaps.

I have an 8600M GT.
mgraesslin
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OlivierToupin wrote:I don't know if there is any disadvantage of using it over pixmaps.

Well the code is let's call it untested. It's there but hardly used and it can happen that it makes KWin rather unstable or results in rendering artefacts. In general the prefered mode is TFP and the other modes are only there for the case that TFP is not supported. So in fact we could drop the code.

 
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