System Monitor constantly redraws until the History page is viewed the first time. Afterwards, redrawing is only done when necessary (e.g., when updating the graphs) regardless of the shown page. To see the redraws, enable the “Show Paint” KWin desktop effect. The constant redrawing is noticeable as flickering. When a page is loaded the first time, a spinning cog is animated to indicate the loading process. Consequently, this causes a flickering “Show Paint” effect. However, the flickering does not stop until the History page is loaded/shown the first time. Until then, it feels as if the cog continues spinning invisibly in the background. On a system with low graphics power and 4k monitor, the load caused by the excessive redraws can actually be noticeable in other applications, which feel less responsive then. With a maximized System Monitor window in the background, hover effects in, e.g., Firefox lag behind mouse movements. The lagging stops when the History page is viewed the first time or the System Monitor window is minimized or closed. Potentially related bugs: Bug 434877: System Monitor has high idle CPU usage Bug 488440: System Monitor has unusually high GPU usage SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 6.2.3 KDE Frameworks Version: 6.8.0 Qt Version: 6.8.0 Kernel Version: 6.12.1-arch1-1 (64-bit) Graphics Platform: Wayland Processors: 8 × Intel® Core™ i5-8250U CPU @ 1.60GHz Memory: 15,4 GiB of RAM Graphics Processor: Mesa Intel® UHD Graphics 620 Manufacturer: LENOVO Product Name: 20L50000GE System Version: ThinkPad T480
For what it's worth, I can reproduce the constant redraws on my system, but viewing the History page doesn't stop them, so it might be a different circumstance? Operating System: Fedora Linux 41 KDE Plasma Version: 6.2.4 KDE Frameworks Version: 6.8.0 Qt Version: 6.8.0 Kernel Version: 6.11.10-300.fc41.x86_64 (64-bit) Graphics Platform: Wayland Processors: 16 × AMD Ryzen 7 7800X3D 8-Core Processor Memory: 30.4 GiB of RAM Graphics Processor: NVIDIA GeForce RTX 4070 SUPER/PCIe/SSE2
Oh wow, I can reproduce this. After opening the history page once and then going to the Processes page, System Monitor drops to about 6% CPU usage, down from 21% normally. So this is definitely at least part of the puzzle.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-systemmonitor/-/merge_requests/326
A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-systemmonitor/-/merge_requests/327
Git commit f2b2739b10ac0ea0575e84c21463a3231df56eab by Arjen Hiemstra. Committed on 19/12/2024 at 18:57. Pushed by ahiemstra into branch 'Plasma/6.2'. page: Hide new pages by default We load pages on request but also in the background if a page requests it. The background loaded pages would be considered visible, resulting in anything relying on said visibility to continue running, such as animations of BusyIndicator. This consequently results in continuous redraws. (cherry picked from commit 92d98f0e8a78335f10d0100f8ab46f621bfd3991) Co-authored-by: Arjen Hiemstra <ahiemstra@heimr.nl> M +4 -0 src/page/EditablePage.qml https://invent.kde.org/plasma/plasma-systemmonitor/-/commit/f2b2739b10ac0ea0575e84c21463a3231df56eab
Git commit 92d98f0e8a78335f10d0100f8ab46f621bfd3991 by Arjen Hiemstra. Committed on 19/12/2024 at 18:52. Pushed by ahiemstra into branch 'master'. page: Hide new pages by default We load pages on request but also in the background if a page requests it. The background loaded pages would be considered visible, resulting in anything relying on said visibility to continue running, such as animations of BusyIndicator. This consequently results in continuous redraws. M +4 -0 src/page/EditablePage.qml https://invent.kde.org/plasma/plasma-systemmonitor/-/commit/92d98f0e8a78335f10d0100f8ab46f621bfd3991