X using 95% CPU (intel, latest git)

Paul Hartman paul.hartman+gentoo at gmail.com
Thu Aug 13 15:16:07 PDT 2009

On Thu, Aug 13, 2009 at 5:01 PM, Andy Neitzke<neitzke at post.harvard.edu> wrote:
> Hi,
> I have a Thinkpad X60t, on which I am running the current git master for
> everything related to Xorg, kernel 2.6.31-rc5-00513-ga3620f7, and KDE 4.3
> (with desktop effects turned on).  lspci shows my video as
> 00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS,
> 943/940GML Express Integrated Graphics Controller (rev 03)
> My problem is that frequently, even when the system should be idle, KDE's CPU
> monitor applet shows that one of the two processors is fully loaded.  When
> this happens, "top" blames the X process, showing it using around 95% CPU.
> The problem doesn't happen at the beginning of an X session, but only once I
> have been running for a while.  Once it happens, though, it persists even if I
> close all open applications, kill the window manager and the Plasma desktop,
> and/or stop the compositing manager.  Quitting and restarting the X server
> does fix it.  I haven't found any way to trigger this problem reliably -- I
> have the impression that suspend/resume brings it on faster, but I am not
> totally sure.  I have had this problem for at least a month, perhaps longer.
> My question is:  how can I diagnose this problem more precisely?  (Is it
> a symptom of an Xorg bug, or could it that some part of KDE is issuing an
> enormous number of requests to the X server for some reason?)

I experienced the same thing with KDE 4.3 and effects turned on, with
the most recent stable releases of kernel/xorg and the nvidia
proprietary drivers. In my case, it would use nearly all CPU for about
a minute, and then it would go back to normal. So maybe you can try
waiting it out and see if it comes back. I do not use suspend/resume
at all (don't even have it built into the kernel) so in my case it
probably had nothing to do with that.

(I ended up just disabling the KDE desktop effects entirely.)

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