[Bug 364359] Re: xserver 1.6.0 - High %CPU/Power Usage with Intel GM965

[Richard Guo]

** Description changed:

  Binary package hint: xserver-xorg-video-intel
  
  This issue is a regression from Hardy. I did a clean install of Kubuntu
  Jaunty RC, using ext4 for partitions. Then I disabled composite effects
  via xorg.conf and KDE4 settings. The first thing I noticed was that the
  laptop (Lenovo T61 with Intel GM965 card) was *noticeably* warmer than
  before, to the point where I can't use it on my lap anymore.
  
  I did some measurements using powertop and top to find the guilty
  process.
  
  Top showed the process Xorg taking up 20% of CPU just to redraw the top
  output. Nothing was open except the konsole window where the testing was
  done. This is in comparison with 1-2% CPU usage on idle for Hardy.
  
  Powertop showed fewer causes for wakeup than before (~100 vs ~180 with
  KDE3 on Hardy), but the CPU spent more time in higher P-states (14% vs
  1%). This is consistent with the Xorg process usage that top showed.
  Absolute power consumption under battery operation. In hardy (sorry, I
  don't have the output of powertop on hardy), the power use was 12 W with
  wireless on, idle, and the dimmest screen brightness. In Jaunty, I'm
  seeing consumption in excess of 15W under the same conditions.
  
  The line "58.5% ( 98.2)       <interrupt> : i915 at pci:0000:00:02.0" made
  me think that something was wrong with the latest Intel video drivers.
  
  I have also attached my xorg.conf file, which has very little deviance
  from defaults (most notably EXA acceleration). The output of lspci -vv
  is also included.
  
  In short, I suspect that this problem is due to Intel 2D causing Xorg to
  do a lot of redraws. Text in particular seems to be slow to process
  (slow konqueror scrolling).
  
  With some research, I also found that framebuffer compression is
  disabled in the 2.6.3 driver due to a bug. That may have caused an
  additional spike in power draw.
+ 
+ At the time of posting, all packages were the latest in the
+ repositories. The kernel version is 2.6.28-11-generic.

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xserver 1.6.0 - High %CPU/Power Usage with Intel GM965
https://bugs.launchpad.net/bugs/364359
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