Created attachment 177126 [details] redacted-journal-log.txt SUMMARY I'm not sure what happened. But suddenly the mouse / touchpad 's move speed is far slower than normal. The keyboard's input speed is slow too. However the audio output is at normal speed. The CPU/Memory usage is normal in the System Monitor. I tried to unplug and plug the receiver of the mouse. it doesn't help I tried `kwin_wayland --replace` and it doesn't help. I tried `systemctl restart sddm` and then re-login . it doesn't help. Only reboot solves the problem. This is the second time i encountered this issue. OBSERVED RESULT Random laggy EXPECTED RESULT No random laggy SOFTWARE/OS VERSIONS Linux/KDE Plasma: Fedora 40 KDE Plasma Version: 6.2.3 KDE Frameworks Version: 6.8.0 Qt Version: 6.7.2 ADDITIONAL INFORMATION The log around the time when laggy happens , shows ``` Jan 05 21:21:53 MACHINE_NAME kwin_wayland[1932]: kwin_libinput: Libinput: event14 - PNP0C50:00 0911:5288 Touchpad: kernel bug: Touch jump detected and discarded. See https://wayland.freedesktop.org/libinput/doc/1.26.2/touchpad-jumping-cursors.html for details Jan 05 21:23:52 MACHINE_NAME kwin_wayland[1932]: kwin_libinput: Libinput: client bug: timer event14 keyboard: scheduled expiry is in the past (-70ms), your system is too slow Jan 05 21:24:07 MACHINE_NAME kwin_wayland_wrapper[2032]: Key repeat discarded, Wayland compositor doesn't seem to be processing events fast enough! ``` I guess this might be related to libinput.
You're right, it is a Libinput issue. Generally when this happens, it's because Libinput enabled pointer hysteresis because it detected that the hardware wasn't providing great enough precision, which can also sometimes happen if the system is under load. IMO this is a terrible mis-feature and 100% of the time when it's triggered for me across four laptops, it's made the situation worse than it would have been without it. You can open a bug report about this at https://gitlab.freedesktop.org/libinput/libinput/-/issues
Update: I opened a ticket on https://gitlab.freedesktop.org/libinput/libinput/-/issues/1074 when i encounter the problem the third time. and they said it is "not our bug" . > so the delay here is caused by the compositor, presumably because it's busy rendering things. I don't know what to do know. :(