Version: (using KDE 4.3.3) Compiler: gcc (Gentoo 4.4.2 p1.0) 4.4.2 OS: Linux Installed from: Gentoo Packages Whenever the slideshow desktop wallpaper changes the wallpaper, the entire system comes to grinding halt for a second or two. It is as though decoding and/or scaling the new wallpaper are being done in a very high-priority thread, and everything else has to wait. Even keyboard input queues up and is only processed by the foreground application after the wallpaper changes. If it matters, I am using a single 2560x1600 monitor on an NVIDIA GeForce 8600 GT (PCI-E 16x, 256 MB) with the 190.42 NVIDIA proprietary driver. My wallpapers are typically 1920x1200 or 2560x1600 JPEGs that are 0.5 to 2 MB in size, so decoding and potentially scaling them is not a trivial computational task. I have compositing enabled in X and in KWin. An interesting note is that a completely independent X.org X11 server instance (a separate X process running on a different virtual terminal, with only MPlayer as a client, no KDE at all, not even KWin) suffers from the same periodic, momentary hang caused by the wallpaper changing in the first X instance. This leads me to believe it's not a problem in the X server, since the second, independent X process is also affected by the wallpaper changing. Could the wallpaper change be done in a lower-priority thread so as not to disrupt system responsiveness? It doesn't really matter if it takes several seconds to render the new wallpaper if I don't notice it happening. At present, I definitely notice it because everything stops responding briefly.
I experience the same bug under KDE SC 4.4.1. It is very annoying, especially when video slows down/stutters every time the wallpaper transitions. Xorg 1.7.5.901, xf86-video-radeon (git), mesa/libdrm/etc.. (git), Kernel 2.6.33 (KMS enabled).
This bug has been fixed on other platforms but not on Linux. We are using a different thread for the wallpaper renderer but according to Qt documentation it's not possible to have threads with different priorities on Linux platform. http://doc.trolltech.com/4.6/qthread.html#setPriority Please, report this bug to kernel developers.
(In reply to comment #2) > it's not possible to have threads with different priorities on Linux platform. That's an outright lie. See the pthread_setschedprio man page.