When I first log in, I experience tearing, even though I have vsync enabled. If I change the vsync type option, apply it, and then disable and re-enable desktop effects, the tearing goes away. Maybe there is some code that is run when changing the vsync type that should also be run when kwin initially starts up, but isn't for some reason. Reproducible: Always Steps to Reproduce: 1. Log in. 2. Observe tearing. 3. Change System Settings -> Desktop Effects -> Advanced -> OpenGL Options -> Tearing Prevention (VSync) option. 4. Disable desktop effects. 5. Re-enable desktop effects. 6. Observe that tearing is gone. Actual Results: There is tearing. Expected Results: As I have vsync enabled, there should not be tearing. GeForce GTX 670 NVIDIA proprietary driver version 331.49
Please post the output of: grep -i triple /var/log/Xorg.0.log and cat /proc/`pidof kwin`/environ See bug #322060 There seems a redetection error about the availability of triple buffering, so you might end up with vsync *invalidly* being enabled.
The grep command yields no output. kwin's environ: XDG_VTNR=7 SSH_AGENT_PID=436 XDG_SESSION_ID=1 DM_CONTROL=/var/run/xdmctl GPG_AGENT_INFO=/tmp/gpg-079kbg/S.gpg-agent:439:1 SHELL=/bin/zsh XDM_MANAGED=method=classic,auto GS_LIB=/home/qmega/.fonts GTK_MODULES=canberra-gtk-module KDE_FULL_SESSION=true USER=qmega XCURSOR_SIZE=0 SSH_AUTH_SOCK=/tmp/ssh-3wxAMquR42L5/agent.435 PAGER=less MOZ_PLUGIN_PATH=/usr/lib/mozilla/plugins PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/vendor_perl:/usr/bin/core_perl MAIL=/var/spool/mail/qmega DESKTOP_SESSION=kde-plasma HG=/usr/bin/hg PWD=/home/qmega JAVA_HOME=/usr/lib/jvm/java-7-openjdk EDITOR=emacs --maximized KDE_SESSION_UID=1000 LANG=en_US.UTF-8 SSH_ASKPASS=/usr/bin/ksshaskpass HOME=/home/qmega XDG_SEAT=seat0 SHLVL=1 KDE_SESSION_VERSION=4 XCURSOR_THEME=Adwaita LESS=iMR LOGNAME=qmega VISUAL=emacs --maximized XDG_DATA_DIRS=/usr/share:/usr/share:/usr/local/share DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-ms0gIsGmBO,guid=2cca3f010c73980fe9dbcf945314bba5 LESSHISTFILE=/dev/null WINDOWPATH=7 DISPLAY=:0 XDG_RUNTIME_DIR=/run/user/1000 QT_PLUGIN_PATH=/home/qmega/.kde4/lib/kde4/plugins/:/usr/lib/kde4/plugins/ XDG_CURRENT_DESKTOP=KDE _=/usr/bin/kwrapper4 SESSION_MANAGER=local/albatross:@/tmp/.ICE-unix/496,unix/albatross:/tmp/.ICE-unix/496 LANGUAGE=
see dupe. activating vsync is actually a bug (improper redetection after reconfigure) do you get "higher" cpu load with working vsync (and no triple buffering nor usleep yielding)? *** This bug has been marked as a duplicate of bug 322060 ***
kwin uses very little cpu power when vsync is working, but I haven't checked it when broken to compare; I'll do that when I get a chance.
No perceptible difference in cpu load between before and after. Using usleep yielding (through a script in ~/.kde4/env) does workaround the problem for me, and doesn't seem to cause any more cpu load, at least as far as I can tell; haven't tested extensively. I'm going to keep that for now, so I'll report if I notice any problems. By the way, issue still exists on kwin 4.11.7 and nvidia driver 334.21. (Sorry for posting in the dup bug, if that's not what you wanted me to do. I'm just replying here because you asked here. I'll post in the main bug in the future if anything changes.)
If at all, yielding usleep is supposed to lower the CPU load (for double buffering) It's ok to post to the bug, it's yours ;-)