10-50% CPU used by xorg?

[Ben E. Hard]

Am Dienstag, 19. Februar 2008 schrieb Daniel Kasak:
> On Tue, 2008-02-19 at 14:47 +0100, Ben E. Hard wrote:
> > 113       0.6208  libexa.so                libexa.so
>
> EXA on Intel 830 systems is bound to be fantastically slow at the
> moment, particularly without a composite manager. We're waiting for LOTS
> of experimental stuff to land: the batchbuffer branch of the Intel
> driver, TTM, DRI2, etc, etc. Last word was that this wasn't happening
> any time soon, so in the meantime, force X to use XAA:
>
> Option      "AccelMethod" "xaa"
Now I have something around 9% with two monitors connected and kmail and a 
konsole-window open. Writing the email doesn't change very much any more, 
stays at around 13 %.
>
> > Ok, I don't know if I use it the same way as you, but your comment
> > made me think, that the behaviour might be quite normal.
>
> No it's not. With XAA you should get quite snappy performance with
> minimal CPU load. My usage is hardly 'normal'. I'm running
> Enlightenment-0.17 with ecomorph ( a compiz derivative ), and I have the
> performance-killing XAANoOffscreenPixmaps option set. With all this
> running, yeah I get X using about 50% of my CPU ( a 2.6Ghz Pentium
> 4 ) ... and this is with everything 'sitting still' so to speak. If I
> don't run a compositing manager, and I use XAA but *not*
> XAANoOffscreenPixmaps, then X rarely gets above 10%.
>
> > I can see for example, that
> > the fact that I'm writing these lines brings X from around 10 % up to
> > 20-30%.
>
> That's EXA.
>
> > Also if I open a konqueror window and move it around
> > fast, X goes up to 80%.
>
> Ahhhh ... the 'window-wanking' test. If you must do this as part of
> everyday use, then run a compositing manager. If you don't want any
> compiz special effects, then the best performance is with XAA,
> XAANoOffscreenPixmaps set, and xcompmgr.
I don't do window-wanking as part of my everyday work, but for testing the 
load of Xorg it seemed to be quite good.  With XAA, it would move xorg only 
up to 50 %, not any more 80% and it seems to be smoother. 

Option "XAANoOffscreenPixmaps" "true" added some 10% to CPU-load, so I removed 
it after testing it. And I don't need a compositing manager, so I think I get 
the best performance for a normal kde 3.5.8 with XAA and not 
XAANoOffscreenPixmaps.

PS: I found bug #13389 relating to that problem, confirming what Daniel has 
said.

Ben
>
> --
> Daniel Kasak
> IT Developer
> NUS Consulting Group
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