KDE 4 drawing performance on nvidia :: Blog

KDE 4 drawing performance on nvidia

(posted at 2008-09-22 13:30:27 UTC)

I've got a fairly high spec machine at home:

Q9300
2 8800GT graphics cards
8GB RAM

Having got most of the way through packaging KDE 4.1.1 for Slamd64, I gave it a try - with one monitor on each of my non-SLIed graphics cards using the (beta) nVidia binary driver and Xinerama.

It was terrible; though the following helped a little:

In xorg.conf:

Option "AllowGLXWithComposite" "true"
Option "AddARGBGLXVisuals" "true"
Option "RenderAccel" "true"
Option "UseEvents" "false"
Option "TripleBuffer" "1"
Option "DamageEvents" "1"
Option "BackingStore" "1"
Option "PixmapCacheSize" "70000"
Option "OnDemandVBlankInterrupts" "true"
Option "AllowSHMPixmaps" "0"
Option "DisableGLXRootClipping"

On each X session:
nvidia-settings -a InitialPixmapPlacement=2 -a GlyphCache=1

This was still unusable.

Now to see if people read more than half my blog post before commenting :) After plugging both monitors into the same graphics card and disabling the other (no twinview on SLI...) it absolutely flies - subjectively, it 'feels' faster than KDE 3, even with all the fancy effects on (including wobbly windows - except for resizing with wobbly windows on isn't so great). As it turns out, the X stuff above does do a difference in this setup.

I'm really impressed by it's performance and the other improvements that have gone in since I've last been able to build and run KDE4, and I hope that the poor performance of nVidia's drivers without lots of tweaks doesn't give too many people an incorrect impression.

Comments

resizing

Posted at 2008-09-22 14:24:51 UTC by "Dass"

try turning off the view of the content of window during resize. yeah, it is win95 like, ok, but it's the only way to have a fast resizing now :-)

Performance

Posted at 2008-09-22 15:25:29 UTC by "Alex"

I have a Debian installation and an Ubuntu installation on my machine, with KDE 4.1 on Ubuntu and KDE from SVN trunk (compiled with debugging info) on Debian. The Ubuntu machine is using the 177.70 driver, and the Debian machine is using 177.76, and the Ubuntu KDE 4.1 installation is really a lot faster. There are too many variables involved for me to find the cause in my limited spare time, but it seems odd that it would be so different. I think KDE trunk was faster on the Ubuntu machine when I used it there, but I've never done a side-by-side comparison of the same commit on both. I guess 2D acceleration is just a really tough problem, both for application developers and driver developers.

Increase PixmapCacheSize

Posted at 2008-09-22 15:35:45 UTC by "Elvis Stansvik"

I think you might want to try a much higher pixmap cache size. It is measured in pixels, so e.g. a value of 70000 won't fit any big pixmaps. A value of e.g. 1000000 would use about 5 MB of your graphics RAM. I'm using 2000000.

Dont need some options

Posted at 2008-09-22 18:29:40 UTC by "Half-Left"

Fred, you dont need some of the options there because they are enabled by default. Option "AllowGLXWithComposite" "true" Option "RenderAccel" "true"

KDE 4 drawing performance on nvidia :: Blog