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January 16, 2010 / P. Filippaios

Interesting discovery: Xrender acceleration in KDE 4.4 with Nvidia is very good actually

Today, I found my self wondering what the Xrender acceleration option in KDE systemsettings can be used for.

The last time I had used Xrender as compositor was almost one and a half year ago, when I used fglrx and an ATi card. Xrender was CPU accelerated, so that means slow composition, and thus, it should be used as a fallback if you really want a composited desktop.

Well, today there was a surprise. Xrender compositing with Nvidia, seemed even FASTER than OpenGL. Yes ! I guess that’s happening with the current beta Nvidia driver (195.52) since I read the nvnews forum (I can’t find the thread right now) that there was a huge 2D and Xrender performance gain in the latest driver update on KDE4. The performance is even higher regarding the awful resizing of the windows (it is happening using every Linux driver out there, so I guess it’s an Xorg problem) which is almost eliminated with Xrender composition.

You can try it: System Settings > Desktop > Advanced (tab) > Composting Type "Xrender" and press Apply.

(Some OpenGL 3D effects are disabled of course)

Nice … 😀

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  1. Chris / Feb 12 2010 10:43 pm

    Yes, just found this one out myself! I’ve been annoyed by the stuttering resizing of windows since 4.0. It has improved somewhat, but it’s still there and it just looks ugly. xrender works better for resizing, but then, i can’t turn on my favorite wobbly windows effect anymore. 😦
    Silly how one gets used to all that eye candy.
    Any suggestions on how to improve OpenGL / Xorg performance when resizing windows?
    using nvidia 190.53.

    • flamelab / Feb 14 2010 8:14 am

      Actually, I don’t know if there is a fix right now :-/

      • Chris / Feb 28 2010 10:50 pm

        When using Ubuntu with Gnome, i found that it defaults to resizing without displaying content in resizing windows. That only occured to me after a few days, so i thought: let’s do that in my Arch Linux KDE 4.4. After a bit of searching, I configured it the way I wanted:
        System Settings – Window Behavor – Window Behavior, tab “moving”. Then uncheck “display content in resizing windows”.
        Then: System Settings – Desktop – tab “all effects”, under Window Management check: “resize window”.
        Dunno if that is any good for you, but for me it’s 2nd best. 🙂

  2. Alejandro Nova / Apr 13 2010 2:36 am

    I have excellent results by disabling “Shadow” in Common Settings, followed by installing a plugin called BeShadowed. The main argument for BeShadowed is: it’s like 10 times faster than KWin’s shadow, and it doesn’t interfere with fullscreen videos. So, the CPU usage and speed has dramatically improved here, I kept my OpenGL composition system, and, what’s best, I can watch DVDs fullscreen with ~20% CPU usage (Turion X2 1.8 GHz, 40% CPU usage of my processor running at 800 MHz)

  3. nortexoid / Jul 11 2010 12:24 am

    On my Intel system, OpenGL compositing is much faster than XRender in some scenarios but I notice that XRender has considerably lower cpu usage, which for my laptop is important for battery life. I’ve since stopped using OpenGL because of this, but I’ve also had to drop some compositing effects I’d ordinarily use like present windows which runs too slow using XRender.

    I also notice that general 2D peformance is faster with XRender, e.g. with scrolling articles in Chrome or Firefox. Xorg, KWin and plasma-desktop all use a lot less cpu with XRender.


  1. 2010 in review « Linuxology

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