kwin_wayland has 100% cpu usage when the screen is locked. It happens only (but 100% of the reproducible) by locking the session. Starting kscreenlocker_greet (with and without --testing) leaves kwin_wayland idle. Running in a QEMU VM with virtio gpu (no hw acceleration). Backtrace: #0 0x00007f02afb234dc in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0 #1 0x00007f02a17b8b23 in ?? () from /usr/lib64/dri/virtio_gpu_dri.so #2 0x00007f02a17c3dfd in ?? () from /usr/lib64/dri/virtio_gpu_dri.so #3 0x00007f02a17c4913 in ?? () from /usr/lib64/dri/virtio_gpu_dri.so #4 0x00007f02a1184481 in ?? () from /usr/lib64/dri/virtio_gpu_dri.so #5 0x00007f02adc27294 in KWin::GLVertexBuffer::endOfFrame() () from /usr/lib64/libkwinglutils.so.11 #6 0x00007f02a31d62d0 in KWin::SceneOpenGL::paint(QRegion, QList<KWin::Toplevel*>) () from /usr/lib64/qt5/plugins/org.kde.kwin.scenes/KWinSceneOpenGL.so #7 0x00007f02b03acb2a in KWin::Compositor::performCompositing() () from /usr/lib64/libkwin.so.5 #8 0x00007f02a3a06e35 in drmHandleEvent () from /usr/lib64/libdrm.so.2 #9 0x00007f02a3a21de9 in ?? () from /usr/lib64/qt5/plugins/org.kde.kwin.waylandbackends/KWinWaylandDrmBackend.so #10 0x00007f02af1f41a0 in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib64/libQt5Core.so.5
100% usage but you can still move the mouse about and stuff? or completely locked? If it is still usable I fear your backtrace is misleading. Output from perf would be better.
(In reply to David Edmundson from comment #1) > 100% usage but you can still move the mouse about and stuff? or completely > locked? I can unlock normally. > If it is still usable I fear your backtrace is misleading. Output from perf > would be better. The perf output is equally misleading, mostly llvmpipe. I assume it gets an infinite stream of DRM events and redraws at the highest possible frame rate or something like that... It does not happen with kscreenlocker_greet (with or without --testing) and kwin_wayland --lockscreen in windowed mode.
What about other fullscreen windows?
(In reply to Martin Flöser from comment #3) > What about other fullscreen windows? I tried konsole in fullscreen mode with wl-shell, CPU usage remained normal. Maybe there's a better application I could try? Manually running kscreenlocker_greet doesn't trigger the issue though.
That could indicate that the problem might be the windows not rendered when the screen is locked.
Given it's reported by Fabian I'm confident he would have poked us directly if this was still an issue.