| Summary: | High CPU usage during intensive scrolling | ||
|---|---|---|---|
| Product: | [Applications] konsole | Reporter: | Yaroslav <yaroslav.rastrigin> |
| Component: | general | Assignee: | Konsole Developer <konsole-devel> |
| Status: | REPORTED --- | ||
| Severity: | major | ||
| Priority: | NOR | ||
| Version: | 22.12.3 | ||
| Target Milestone: | --- | ||
| Platform: | Other | ||
| OS: | Linux | ||
| Latest Commit: | Version Fixed In: | ||
I can repro the same issue with qterminal , but with smaller performance hit (CPU usage hovers in 20% to 50%, which is still too much compared with VTE-based terminals). Highest CPU consumer is the same (alphargbblend_argb32 ) |
SUMMARY *** scrolling a lot of text incurs large performance overhead. konsole is consuming up to 65% of a single core if I'm doing, f.e. , `tail` -f of a quickly updating log file *** STEPS TO REPRODUCE 1. induce scrolling . easiest way is to run 'while [ 1 ] ; do echo 'testtesttesttesttest' ; done 2. open `top` or run another performance monitor OBSERVED RESULT high cpu usage, over 50% of a single core EXPECTED RESULT negligible cpu usage, as with other terminal emulation software SOFTWARE/OS VERSIONS Linux/KDE Plasma: KDE Plasma Version: kde-frameworks/plasma-5.104.0:5/5.104 KDE Frameworks Version: 5.104 Qt Version: 5.15.8 ADDITIONAL INFORMATION I have tested this with both Gentoo packages built from source by myself , and precompiled Arch linux packages. During investigation I've compiled konsole and QtGui with debugging symbols, and ran `perf record` + `perf report` dwhile reproducing the issue. The culprit seems to be incorrect or excessive usage of alphargbblend_argb32 37.13% 0.00% konsole libQt5Gui.so.5.15.8 [.] QtSharedPointer::ExternalRefCountWithCustomDeleter<QColorTrcLut, QtSharedPointer::NormalDeleter>::deleter | ---QtSharedPointer::ExternalRefCountWithCustomDeleter<QColorTrcLut, QtSharedPointer::NormalDeleter>::deleter 0x5645ea71a9c0 | |--31.87%--alphargbblend_argb32 | --5.26%--qt_alphargbblit_argb32