https://bugs.kde.org/show_bug.cgi?id=468259
Bug ID: 468259
Summary: High CPU usage during intensive scrolling
Classification: Applications
Product: konsole
Version: 22.12.3
Platform: Other
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: general
Assignee: konsole-de...@kde.org
Reporter: yaroslav.rastri...@gmail.com
Target Milestone: ---
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
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