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Xorg is constantly using about 80% cpu power, on a single core. And I have no idea how to get it normalised

I'm running Linux Mint 10 on an HP Envy 17 laptop with an AMD/ATI card.

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What window manager are you using, Metacity? Also, do you have openjdk or Sun Java? –  Blomkvist May 5 '11 at 18:04
    
I'm using compiz and Sun Java –  skerit May 5 '11 at 18:13
    
You might try bumping down to metacity to see if anything changes. It's been a while since I've used Mint but I believe it still defaults to it if you select 'none' under desktop effects. –  Blomkvist May 5 '11 at 18:32
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1 Answer

The Problem

I've asked around. This is a persistent problem for everybody using the FGLRX graphics driver.

From my testing with similar computer specifications, I have recreated this Xorg issue many times.

When I recreate it,

  • the Xorg process uses up almost an entire core (It's single-threaded, so it cannot use more than one core.)
  • Xorg may consume over 1 GiB of RAM
  • the desktop environment may be obnoxiously unresponsive (confirmed with both KDE and GNOME)
  • a large portion of this excessive RAM usage may be swapped out to a SWAP partition
  • swapoff -a does not improve performance because the memory swapped out does not appear to be used

The FGLRX graphics driver is the worst graphics driver ever, in my opinion. Not only does it produce issues with Xorg from the kernel level, it also makes your laptop less portable in that display configuration changes are no good unless you restart your computer.

I nailed down two major causes for this stress on Xorg:

  • Skype
  • Java

There's also another thing that causes graphics issues, but I didn't confirm its connection to the Xorg problems:

  • Flash

Skype

Whenever Skype 2.2 Beta was running, frame rate for everything in the desktop environment would drop, sometimes even the mouse cursor would freeze. The effects compound over time, so the longer Skype is left running, the more the desktop becomes unbearable. Skype 4.0 ameliorates the issues, but it still occurs.

I don't know how to investigate why, but you may notice that Skype doesn't look "native" to other applications in your operating system, so its unusual ways of rendering may contribute to the high CPU usage.

Skype is also sometimes resistant to commands like killall skype when it crashes. In these cases, do killall -9 skype instead.

Java

Lots of Java programs cause Xorg to flare up, but so far, I've only confirmed the ones that render graphical user interfaces. This includes, RuneScape, and... oh, Minecraft! Minecraft is the biggest culprit, as this Super User question shows.

When Minecraft (or some other graphics-heavy Java program) freezes, like Skype, it also becomes resistant to killing.

Again, this might be because Java renders graphics differently.

 

The Solution

Though I don't know what FGLRX does so arrantly wrong, it must be leaving behind elements that aren't cleaned up.

The most conservative solution is to reboot your computer.

To eliminate the problems that FGLRX causes, uninstall FGLRX. But I wouldn't recommend this. On an HP Envy 17, your display may be unstable, and some seemingly harmless actions like listing WiFi networks would cause the screen resolution to change suddenly.

Unfortunately, your graphics card is integrated, so you can't exchange it, at least not easily.

Linux is the only major operating system (of Windows, Mac, and Linux) that does not support ATI graphics cards well. Switching to Microsoft Windows eliminates the graphics problem, but who would do that? ;)

Next time you buy a computer, do not buy one with an ATI graphics card.

These are unfortunately the only things you can do. I've been searching for a solution for a year now, and nothing good has turned up...

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I have similar problems, but I have a nvidia card. Sorry :-) –  dmatej Feb 20 at 12:25
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