I'm running into terrible performance with KWin when it's running in OpenGL mode. I usually have Second Life running in the background and do other things such as web browsing, talking on IRC and listening to music, however there's some really bad problem with both SL and KWin are running.

My system before I go any further:

CPU: AMD X4 Phenom II 965 @ 3.4GHz (Cool 'n Quiet disabled)
RAM: 8GiB DDR3 @ 1333MHz
GPU: NVIDIA GTX 560 Ti 1GiB (set to maximum performance)
OS: Kubuntu 12.04
KDE: 4.8.3
NVIDIA driver: 295.40
Monitor resolution: 1920x1080

When the SL client/viewer becomes inactive, it yields so other programs can use the CPU and GPU. However, even when the GPU is hardly under load in this case, moving windows around with KWin in OpenGL mode causes a lot of stuttering, and Xorg's CPU usage jumps to 20-30% (that's of one core), not to mention the inactive frame rate of SL begins to drop. All animations also begin to suffer in the process, even though there's plenty of GPU cycles and VRAM available. This makes the desktop experience rather horrible.

I've tried with absolutely no plugins running, and it makes no difference at all. I've tried using XRender, which runs animations incredibly slow, but window moving has no problem - however I can't use XRender because of a showstopper bug that causes Xorg to lag to death and lock up when the video memory is exhausted. Compositing off, window movements always stay smooth, and SL's performance infact goes up in the process. But I don't want to keep it off, as it means I can't use features such as present windows, which helps managing windows greatly.

If the SL client starts to stress the GPU and it's active, the client also starts to lag terribly. Shutting off compositing again results in a drastic performance boost, for example, 40 FPS to 58 FPS in the SL client (I've tested this and got these results).

I've tried Xorg options such as use events, backing store, enabled vertical sync in OpenGL, triple buffering, and they don't help at all.

Why is KWin hindering performance so badly?

EDIT: I'd like to also point out that if I suspend effects on KWin using the shortcut with SL running, compositing turns off perfectly. However when turning them back on, there's a very high chance that KWin will lock up, and I'll have to kill Xorg to get my desktop working again.

was this a non-issue until a recent gpu driver upgrade ? there were performance issues with the drivers you use and Nvidia updated that series to fix the regression http://www.phoronix.com/scan.php?page=n ... px=MTA5NjQ

google01103 wrote:was this a non-issue until a recent gpu driver upgrade ? there were performance issues with the drivers you use and Nvidia updated that series to fix the regression http://www.phoronix.com/scan.php?page=n ... px=MTA5NjQ

This has been an issue for quite some time. That regression is related to the security vulnerability and the GeForce 6 and 7 series, not the 500.

EDIT: I'd like to also point something else out that's really bad when SL and KWin are both running. If I suspend effects on KWin using the shortcut, it turns off perfectly. However when turning them back on, there's a very high chance that KWin will lock up, and I'll have to kill Xorg to get my desktop working again.

Koli wrote:I've tried using XRender, which runs animations incredibly slow

There's sth. really wrong - the nvidia blob is /really/ good at xrender. I'd rather say SL yielding causes this.
Attempt to
__GL_YIELD=NOTHING <secondlife_command>

luebking wrote:There's sth. really wrong - the nvidia blob is /really/ good at xrender. I'd rather say SL yielding causes this.
Attempt to
__GL_YIELD=NOTHING <secondlife_command>

Well, something is wrong then because XRender shows rather slow animations even when SL /isn't/ running, such as the slide animations for Plasma.

Another thing I have now noticed is that even when SL isn't running, I can't switch back to OpenGL mode from XRender. I get a black screen and KWin switches back to XRender (because it failed to initialise).

I can tell something is really broken here. =/

Well well, I've fixed the lag being caused when SL was inactive. It's NVIDIA's fault - PowerMizer was reducing the GPU clock to 405MHz (performance level 1), which then caused KWin to stutter and Xorg's CPU usage to go up. Forcing it to 'prefer maximum performance' fixed it right away, and I've added something into my Xorg.conf so it /stays/ that way. Now my entire desktop stays smooth while SL is inactive.

The problem where KWin causes demanding scenes in SL to lag more than when compositing is off is still an issue though, but I'm starting to assume that's not fixable.