Created attachment 164388 [details] Flamegraph SVG of kwin_x11 at a constant but not debilitating load SUMMARY Logged into my Plasma 6.0 Beta dev session (built two days after Beta 2) and the fans started spinning. On an 8-core Intel Core i7-8565U, ThinkPad X1 Carbon Gen 7 laptop with iGPU, ksysguard showed a constant 13%-14% of CPU usage for kwin_x11 and 4%-5% for picom. So it didn't quite incapacitate the system, and cursor overlays were fluid but window moves were at an estimated <5 FPS. I don't have a full stacktrace, but I used https://github.com/flamegraph-rs/flamegraph to capture a few seconds of constant load and generate a flamegraph SVG. Find the SVG attached. It looks like debuginfod was not used because the system-level libraries don't show function-level info. Sorry. I figure the actual perf.data output is also not useful outside of my system, but I have it sitting here for a few days until I rebuild kwin again sometime. STEPS TO REPRODUCE 1. Log into a KF6 X11 session. 2. Get lucky, notice high system load. 3. ??? 4. `perf` it! SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 5.91.90 KDE Frameworks Version: 5.248.0 Qt Version: 6.6.1 Kernel Version: 6.6.3-arch1-1 (64-bit) Graphics Platform: X11 Processors: 8 × Intel® Core™ i7-8565U CPU @ 1.80GHz Memory: 15.3 GiB of RAM Graphics Processor: Mesa Intel® UHD Graphics 620 Manufacturer: LENOVO Product Name: 20QD001VUS System Version: ThinkPad X1 Carbon 7th ADDITIONAL INFORMATION * The session I had previously logged into was a Plasma 5.27.9 session on X11. (Picked the wrong X11 SDDM entry because usually this user account is reserved for Plasma 6 only.) * Upon logout from the CPU-intensive KF6 X11 session, SDDM did not come back and the screen stayed black. Probably unrelated as it also happened after the next session. * Following a hard reboot, I logged into the same KF6/X11 Plasma session again to see if the issue is always reproducible. It is not, CPU load was nice and low now.
There's nothing in that flamechart, that indicate high CPU is at play. It's idling. >* Following a hard reboot, I logged into the same KF6/X11 Plasma session again to see if the issue is always reproducible. It is not Lets keep an eye on this, for now it's inactionable