Fedora-10 nightmare update2

Todd Denniston Todd.Denniston at ssa.crane.navy.mil
Mon Apr 20 23:01:59 UTC 2009


Arne Chr. Jorgensen wrote, On 04/17/2009 03:02 PM:
> hi,
> 
> I did describe noise/glitches on the screen.  
> 
> 
> I will try to describe it a little bit:  
> ---------------------------------------
> 
> It is like an old CRT with a weak
> high voltage supply - the screen may shrink or expand. And there are noise
> streaks across the screen.
> 
> As this is a laptop with LCD, it has to do with updating of the screen. Loading is typical if you open a folder on the screen, and it will update/paint to the screen. In such cases the shrinking/expansion may be
> 20-40 mm for a brief half second or so. Sometimes leaving a horizontal band
> for in the middle.  
> 
>                               
> The reason:
> -----------
> 
> The "new" cpu scaling can not keep up. I have it set to "on-demand".
>  800MHz - worst, as described above.
> 1600MHz - very improved, the shrinking/expanding is only 5-10 mm 
> 1800MHz - the effect seem gone.
> 2000MHz - have not seen any noise/glitches.
> 
> 
> Discussion:
> -----------
> 
> Watching the System Monitor, the graphs are smooth, the loading on CPU1 and
> CPU2 seem nice compared to earlier kernels with abrupt switching from one
> to the other. 
> 
<SNIP>
> 
> To remove noise on the screen, perhaps a sharper controller term could be
> used, at the cost of the more smooth behaviour it has now. Perhaps the
> refresh of the screen could be held off/protected during scheduling. I don't know. 
> 
> Knowing some reasons for this and if need be, just enable a higher prosessor speed, works for me.
> 
> //ARNE

Question:
if you do
taskset -p 0x00000002 \
  `ps aux |grep /usr/bin/Xorg| \
   grep -v grep |awk '{print $2}'`

{painful way to get the X pid to feed to taskset, which suggests to the kernel 
keep the X process on the second processor.}

and then run your tests, does the problem seem less troublesome at the lower 
speeds?


-- 
Todd Denniston
Crane Division, Naval Surface Warfare Center (NSWC Crane)
Harnessing the Power of Technology for the Warfighter




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