https://bugs.kde.org/show_bug.cgi?id=430565
Bug ID: 430565
Summary: PopupMenu renderer and plasmashell lockup bug
Product: frameworks-plasma
Version: unspecified
Platform: Gentoo Packages
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: libplasma
Assignee: notm...@gmail.com
Reporter: lanthrus...@gmail.com
CC: plasma-b...@kde.org
Target Milestone: ---
SUMMARY
KDE Plasma 5.20.4
POPUP application launcher and other dialogs suffer from massive plasmashell
renderer lockup issues mitigated by hardware OpenGL support and powerful CPUs.
When a users clicks on Launch button it would first render the frame then on
some computers after 5 or more seconds it the menu would appear. Then when you
go to the next level the situation repeats. The second time you go through the
same menu route it's faster. The same happens with some other plasma dialogs.
More info:
Linux 1025c 4.14.209-gentoo-x86_64 #1 SMP PREEMPT Thu Dec 10 19:00:20 MSK 2020
x86_64 Intel(R) Atom(TM) CPU N2800 @ 1.86GHz GenuineIntel GNU/Linux
STEPS TO REPRODUCE
1. Find a laptop with GMA3600.
2. Turn of GMA3600 in the kerne v4.14.*l
3. Use xorg-server-1.20.8-r1 with sddm launcher and modsetting driver
4. Install KDE Plasma 5.20.4
OBSERVED RESULT
Multiple lockup issues in plasmashell
EXPECTED RESULT
Linux/KDE Plasma: 4.14.209-gentoo-x86_64 Plasma 5.20.4
(available in About System)
Qt Version: 5.15.2
ADDITIONAL INFORMATION
That is certainly a bug. I experimented quite a lot with that box. It happens
like in the summary with all of a sudden plasmashell taking all 100% of a CPU
thread and it goes on and on and during all this time plasma gets unresponsive.
Turning off Compositon or changing turning off or on effect doesn't help. The
performance is all the same. It happens with some KDE apps too. Never happens
with the other apps like VLC with QT5 or LXQT apps. GMA3600 in kernel support
is quite fast. And ASUS 1025C 64bit platform with 4Gb of memory is very
responsive. For example I'm having now 10 load average on 4 threads compiling
chromium and firefox and other apps in different terminals and it responding
amazingly well for that CPU. LXQT all so works staying amazingly responsive.
But with plasma there is a lockpu bug. Plasma it very fast drawing windows with
all the decorations and transparencies but opening a popup or initiating a some
settings dialogs are causing plasmashell lockup for a period of 4 to 40
seconds. It looks like you click on a menu with only 1 item and you have to
wait for 20 seconds. I have no other QT5 application that behaves the same on
this box but KDE apps and plasma itself.
At the same time FPS is not suffering it always as high as 25 and everything
look smooth except these lockups. The logs have nothing special to tell.
I've done nearly a lot of testing in the past week over this issue and nothing
seems to help. The hardware platform and other apps performance and responses -
outstanding but KDE plasma suffers.
I'm ready to nail down this problem and provide all possible assistance to find
out the cause of that. You many not notice the lags because of the the powerful
CPU and hardware opengl support which GMA3600 lacks.
The difference between Plasma opening a popup menu with a single item and LXQT
doing the same or other QT5 apps like VLC is nearly 100 times. That is
amazingly high difference not accountable by slow processor. During all that
difficult times it's always plasmashell taking 100% of the thread for 5-20
seconds or more and then the menu appears.
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