kwin performance gets worse and worse with every release

Duncan 1i5t5.duncan at
Wed Jun 29 23:43:39 BST 2011

Nikos Chantziaras posted on Wed, 29 Jun 2011 16:15:54 +0300 as excerpted:

> On 06/29/2011 03:45 PM, phanisvara das wrote:
>> On Wed, 29 Jun 2011 17:14:33 +0530, Nikos Chantziaras<realnc at> 
>> wrote:
>>> I just installed KDE RC1.  The trend of kwin becoming slower and
>>> slower continues with this release.  I remember KDE 4.3 (or maybe 4.2)
>>> where kwin was fast and nice.  After every release, it would become
>>> slower. It reached a negative peak with 4.6.  Now with 4.7 RC1, kwin
>>> has become even more slow.  It's extremely annoying to use.
>>> What is happening to kwin?  It's becoming the definition of "sluggish
>>> GUI".  Out of every window manager I have tried, kwin is now the
>>> slowest of them all.
>> hm, perhaps other factors, like distribution, version of kernel and/or
>> Xorg have something to do with that, as well as compiz and video
>> card/driver.
> Nothing else changed.  The only thing was the KDE update.
> I'm using a Radeon HD4870, kernel, xf86-video-radeon/xorg/mesa
> latest versions, KMS.  Gentoo Linux AMD64.

That's very interesting.  Because my experience running Gentoo ~amd64 
with a Radeon hd4650 (rv730 chip, AGP bridged as my workstation is 2003 
vintage, pre-PCIE), native/freedomware xorg/kernel/mesa drivers, etc, has 
been quite good.  And I /believe/ the hd4870 (rv770 chip according to the 
radeon manpage shipped with xf86-video-ati) is supposed to be a higher 
grade chip within the same GPU class. <shrug>

When I first switched to kde4, back with 4.2.4, I was using an old Radeon 
9250 (rv280 chip).  kde4 performance was /bad/, because at the desktop 
resolutions I was running, that chip couldn't do OpenGL, so it was 
limited to xrender/composite.  But I bought the hd4650 upgrade almost 
entirely for kde4 and I've not been disappointed in the least, tho at 
first I had to run "live-git" versions of various components to get OpenGL 
support for it, as nothing released supported OpenGL for it at the time.  
But that hasn't been the case for quite some time, now (tho I did run 
live-git xf86-video-ati in ordered to run a newer xorg-server early in 
the xorg-server-1.10 series, but that wasn't a hardware issue, only 
because I wanted to run the newer xorg-server and there wasn't a released 
xf86-video-ati driver for it yet).

So either there's some quirk in the specific hardware you have, or it's 
down to the software versions of something or other.

FWIW, I do NOT have a dri.conf as you mention helped for you, later in 
the thread, so that's not it, and what few non-default xorg.conf.d device 
section option tweaks I have don't seem to seriously affect kwin speed at 

I *DO* tend to run as leading edge releases of xorg/kernel etc as I can 
possibly get ahold of, indeed, as mentioned, occasionally running live-
git, tho that's not routine except for the kernel, as I DO regularly run 
Linux mainline git kernels, testing and reporting bugs upstream as 

FWIW current installed versions are: xorg-server-1.10.2, xf86-video-
ati-6.14.2, mesa-7.10.3, libdrm-2.4.26.  As mentioned I run git kernels, 
and am currently running 3.0-rc5 (I happened to git-pull right at the rc-5 
tag, apparently).  kde 4.6.4, of course.

I'm running kms, classic-non-gallium (gallium freezes here, I suspect due 
to an agp incompatibility they've not caught).

But obviously I've upgraded both kde and the kernel/xorg/mesa set in 
parallel with kde, and since I switched to the hd4650 (and to kms at very 
nearly the same time), I've had no performance complaints about kwin at 
all.  In fact, I deliberately set the effect speed at "slow" on the 
general tab of desktop effects, so they'd actually last long enough to 
enjoy a bit! =:^)

The dri.conf setting you mention further downthread suggests that your 
problem may be vertical-blanking-sync related.  I don't know, as I've 
experimented with that checkbox on the advanced tab of kde's desktop 
effects settings, but as you mention, it doesn't appear to make a 
difference by itself.  I have the following three settings in the file 
containing the device section in my xorg.conf.d, but again, they don't 
/appear/ to make that much difference.

        Option          "ColorTiling"           "On"
        Option          "SwapbuffersWait"       "Off"
        Option          "EXAVSync"              "Off"

FWIW, glxgears always times at ~60fps, the refresh rate on my monitors, 
so as you before the dri.conf setting you mentioned, I do seem to be vert-
refresh-locked, but that does NOT appear to seriously affect kwin 

The one setting that I HAVE noticed makes a BIT of difference, but only 
in which effects work, NOT in overall performance, at least noticeably, 
is AIGLX.  The setting in question (the desktop effects checkbox doesn't 
seem to matter) is an environmental variable.  I have it in my .bashrc (I 
login at the CLI, then use startx to start kde, so .bashrc set variables 


With that commented (thus direct), kwin's blur and invert effects work, 
but the snow effect doesn't.  With that uncommented (thus indirect), it's 
the inverse, snow works, but invert and blur don't.

Meanwhile, thanks for the dri.conf hint.  Hopefully that's what I need to 
get unlocked from the 60 Hz refresh and see what this thing can REALLY 
do.  I have some experimenting to do, now. =:^)

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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