Desktop effects with intel 945

[Duncan]

David posted on Mon, 25 Oct 2010 02:01:54 +0200 as excerpted:

> Good morning,
> 
> I am using Kubuntu 10.10 (maverick) and this happens both with the
> official
> KDE 4.5.1 in ubuntu's repos, and with KDE 4.5.2 in ubuntu's ppa. Every
> time
> I log into KDE, the desktop effects start suspended, I can re-enable
> them
> with Alt + Shift + F12, but then the graphics slow down significantly.
> The
> worst is with Firefox: when switching to another tab, the redraw takes
> almost two seconds, and (worse), when jumping in a page (by searching
> with
> Ctrl+F, or by scrolling with "Page Down"), the redrawing is often crappy
> (some bits of the old draw overlay on the new draw).
> 
> Do you know whether this is a kernel, or xorg's intel driver, or KDE, or
> kubuntu, issue? Do you know any way of not having KDE with desktop
> effects
> run bloated and faulty (specially with firefox, but the slowness happens
> with all windows in general)?
> 
> My card is "Intel Corporation Mobile 945GM/GMS, 943/940GML Express
> Integrated Graphics Controller (rev 03)", and the composition of Windows
> 7
> runs quickly and flawlessly.
> 
> Thank you very much in advance,
> 
> David
> PS: For convenience, can you please Cc any replies to me?
> Good morning,<br><br>I am using Kubuntu 10.10 (maverick) and this
> happens both with the official KDE 4.5.1 in ubuntu's repos, and with
> KDE 4.5.2 in ubuntu's ppa. Every time I log into KDE, the desktop
> effects start suspended, I can re-enable them with Alt + Shift + F12,
> but then the graphics slow down significantly. The worst is with

[posted/mailed as requested]

[PS: For convenience, can you refrain from posting the HTML version next 
time?  You may or may not see how it jumbles together, there, and I almost 
missed your PS as a result.  Plain text works best on the lists.]


You've been hit with the fallout from a rather controversial bug.  You can 
google it if you want and get the response straight from the KWIN folks, 
but I don't have the time to look it up ATM as I'm headed for work.

Basically, what happened is this.  With kde 4.5, some OpenGL accelerated 
effects were taken advantage of, IF AND ONLY IF the driver claims to 
support them.  KWin asks your graphics driver which OpenGL features it 
supports, and makes use of the features the driver claims it does support.

Unfortunately, certain versions of the native xorg Intel drivers 
(especially, the native xorg Radeon drivers have similar but not as bad 
issues) make claims about features they really don't support, at least in 
hardware.  Some of these are implemented in software, some, buggily, in 
hardware.

So KWin is simply taking the driver at its word when it says it supports a 
feature, and using it.  Unfortunately, this slows things down dramatically 
when it's all software/CPU implemented, as is the case sometimes.

But the driver folks claim that many games test for functionality they 
don't actually use, at least not much, so making those claims allows 
certain games to run with better effects at reasonably high speeds, since 
they're not actually using what they test for much anyway.  Failing to 
make those claims would mean not supporting those games, or at least, not 
supporting certain effects on those games that actually work fine, in 
practice.

So you see it's not quite all KDE/KWin's fault, not all xorg/driver folks, 
and not all the game people.  But the user is caught in between.

Now that the controversy arose, the kwin and driver folks are talking a 
bit, and things should get a bit better.  Actually, they already are in 
some cases, IF you're running the newest xorg/kernel/drivers, just as 
you're running the latest KDE 4.5.1/4.5.2.  But the distributions freeze 
and start testing the xorg/kernel/drivers combo earlier in the cycle than 
KDE, apparently, so while they may ship with the newest KDE, the kernel/
xorg/drivers combo isn't always synced well with it, and that's what 
happened here.

By the 1H2011 edition, hopefully, the rest of the platform shipped by the 
distributions will be caught up, and things will be better.

Meanwhile, experiment with toggling individual effects on and off.  You 
can likely find a combo that's faster, without turning off everything, 
because not every effect uses the same OpenGL features.  Also, try 
changing the effect speed, from normal, to shorter/faster, or to 
"instant".  That helped dramatically on my old Radeon 9200 series card 
(with an older kde4 tho) before I upgraded.

And kwin actually does some checks before enabling things too, in addition 
to the claims.  That's why it's disabling effects at bootup, because it 
sees that not all is as it should be, so rather than leave someone with an 
unusuable desktop, it disables effects to start off with.  FWIW, I'm 
seeing similar disabled to start here on my Radeon hd4650 (the upgrade), 
but with effects like explosion off, things work fine on the Radeon, at 
least with the latest drivers/kernel/mesa/xorg/etc.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

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