SUMMARY Mouse movement stutter/freezes during heavy disk IO (eg: during application upgrades from the software center). STEPS TO REPRODUCE 1. Use KDE Neon 24.04 (Wayland) 2. Perform an application upgrade using the software center 3. attempt to move mouse and observe it freeze for brief moments multiple times during the upgrade OBSERVED RESULT Mouse stutters EXPECTED RESULT Mouse does not stutter SOFTWARE/OS VERSIONS Linux/KDE Plasma: KDE Neon 6.2 KDE Plasma Version: 6.2.2 KDE Frameworks Version: 6.7.0 Qt Version: 6.8.0 ADDITIONAL INFORMATION I believe this to be a regression as I do not remember experiencing this issue on Plasma 6.1 and earlier versions.
Are you by any chance forcing the use of the software cursor? What does `env | grep KWIN_FORCE_SW_CURSOR` in a terminal window say?
(In reply to Nate Graham from comment #1) > Are you by any chance forcing the use of the software cursor? What does `env > | grep KWIN_FORCE_SW_CURSOR` in a terminal window say? I am not forcing the use of the software cursor. There is no such variable set in the environment (the output of the command is nothing).
To provide a little more context. It actually seems like the entire output to the screen freezes, not just the mouse. For example, if some window is animating or if a video is playing, it will stutter/freeze at the same time as the mouse. This isn't with a slow HDD either, I am using an NVMe SSD.
I think this is still present in Plasma 6.4.2. It seems like disabling swap makes it a lot less likely, but it can still happen. I've seen the following pattern on a friend's computer: - it seems to happen more frequently during interactions such as right clicking - when it happens, CPU "kernel" time spikes to 100% on one CPU cores Everything suggests that this is I/O related. Ideally, compositing or "updating the screen" should be completely decoupled from any I/O. Last time I talked to the KWin people they told me that this is not currently the case and it wouldn't be an easy task.