Let me start by saying that I've searched high and low for a definitive fix or workaround for this to no avail. So maybe the answer is here
CPU: Intel Core 2 Duo E6700
MB: Asus P5W64WS
Gfx Card: EVGA Geforce 7950GT KO 512MB GDDR3 PCI-E x16
MEMORY: CORSAIR XMS2 2GB (2 x 1GB) SDRAM DDR2 800
OS: Gentoo (Gentoo Sources 2.6.19-r5, 2.6.18-r6)
Drivers: Nvidia 1.0.9476, 1.0.9631
1) When attempting to run the latest SVN Gentoo Xeffects Beryl Package (9999) using the Nvidia XGL setup, I noticed a consistent 15 to 30 sec 'freeze' every time I tried to minimize a window. By freeze, I mean the mouse was still responsive, but nothing else on the KDE desktop would respond to clicks. After the freeze period, any clicks I had previous made on icons or menus would be executed. I began looking at all of the system logs to see if the kernel was reporting any issues. The output of the logs (and dmesg) showed nothing, but the Xorg logs displayed this:
(II) evdev brain: Rescanning devices (2).
(II) Logitech MX1000-usb-0000:00:1d.0-1/input0: On
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x000085e4, 0x000085e4)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x0000e75c, 0x0000e75c)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x0000e780, 0x0000e780)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x0000fa30, 0x0000fa30)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x0000e4e0, 0x0000e4e0)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x00000f70, 0x00000f70)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x000011e4, 0x000011e4)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x000046f4, 0x000046f4)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x0000f568, 0x0000f568)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x00008a00, 0x00008a00)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x00003608, 0x00003608)
(WW) NVIDIA(0): WAIT (0, 7, 0x0000, 0x00004c5c, 0x00004c5c)
2) I tailed the Xorg log and noticed that these WAIT messages did, in fact, seem to correlate with these 'freeze' events.
3) I then disabled beryl; rebooted my system; started a normal KDE session and simply ran glxgears to try to narrow the issue down: was it beryl or the nividia drivers themselves that were responsible for the freeze events?. I was tailing the Xorg log and again noticed this 'freeze' effect, which correlated perfectly with the Xorg log entries I posted above. The output of glxgears was showing a very high frame rate compared to any previous versions of the nividia-drivers I'd tried (:
83904 frames in 5.0 seconds = 16780.706 FPS
84805 frames in 5.0 seconds = 16960.986 FPS
84586 frames in 5.0 seconds = 16917.156 FPS
84794 frames in 5.0 seconds = 16958.705 FPS
84848 frames in 5.0 seconds = 16969.597 FPS
84764 frames in 5.0 seconds = 16952.688 FPS
84644 frames in 5.0 seconds = 16928.739 FPS
3) I reverted the nvdia-drivers from 9476 to 9631 and still observed the same issue.
Here are some of the things I've tried to work-around/fix the problem:
1) I commented out the 'RenderAccel' entry in my xorg.conf - No effect
2) I loading the nvidia driver module with the "modprobe nvidia NVreg_RegistryDwords="PerfLevelSrc=0x2222" - No effect
Here's the device section of my my xorg.conf, btw:
Identifier "EVGA GeForce 7950GT"
Option "RandRRotation" "on"
# Option "RenderAccel" "true"
Option "DPMS" "true"
Option "UseEvents" "true"
Option "NvAGP" "0"
# Required for XGL
Option "AddARGBGLXVisuals" "true"
# Insert Clocks lines here if appropriate