Please ask if you need more info. Thanks for your job! :o)

another stacktrace a while later:

thread apply all bt full

Thread 13 (Thread 0x7ffef7082700 (LWP 17326)):
#0  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#1  0x00007fffe5ee5ee1 in  () at /usr/lib/libpulse.so.0
#2  0x00007fffe5ed76f1 in pa_mainloop_poll () at /usr/lib/libpulse.so.0
#3  0x00007fffe5ed7d8e in pa_mainloop_iterate () at /usr/lib/libpulse.so.0
#4  0x00007fffe5ed7e40 in pa_mainloop_run () at /usr/lib/libpulse.so.0
#5  0x00007fffe5ee5e29 in  () at /usr/lib/libpulse.so.0
#6  0x00007fffe5875fe8 in  () at /usr/lib/pulseaudio/libpulsecommon-10.0.so
#7  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 12 (Thread 0x7ffef870b700 (LWP 17325)):
#0  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#1  0x00007fffec0eabf9 in  () at /usr/lib/libglib-2.0.so.0
#2  0x00007fffec0ead0c in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#3  0x00007ffff1e57e7f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007ffff1dfe21a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#5  0x00007ffff1c2040a in QThread::exec() () at /usr/lib/libQt5Core.so.5
#6  0x00007ffff4d8f645 in  () at /usr/lib/libQt5Qml.so.5
#7  0x00007ffff1c24cbd in  () at /usr/lib/libQt5Core.so.5
#8  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#9  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 10 (Thread 0x7fff0d57e700 (LWP 17300)):
#0  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#1  0x00007fffec0eabf9 in  () at /usr/lib/libglib-2.0.so.0
#2  0x00007fffec0ead0c in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#3  0x00007ffff1e57e7f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007ffff1dfe21a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#5  0x00007ffff1c2040a in QThread::exec() () at /usr/lib/libQt5Core.so.5
#6  0x00007fff0ec03427 in KCupsConnection::run() () at /usr/lib/libkcupslib.so
#7  0x00007ffff1c24cbd in  () at /usr/lib/libQt5Core.so.5
#8  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#9  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 9 (Thread 0x7fff3747f700 (LWP 17289)):
#0  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#1  0x00007fffec0eabf9 in  () at /usr/lib/libglib-2.0.so.0
---Type <return> to continue, or q <return> to quit---
#2  0x00007fffec0ead0c in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#3  0x00007ffff1e57e7f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007ffff1dfe21a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#5  0x00007ffff1c2040a in QThread::exec() () at /usr/lib/libQt5Core.so.5
#6  0x00007ffff5947836 in  () at /usr/lib/libQt5Quick.so.5
#7  0x00007ffff1c24cbd in  () at /usr/lib/libQt5Core.so.5
#8  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#9  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 8 (Thread 0x7fff3cd0f700 (LWP 17287)):
#0  0x00007ffff0df339d in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007fffc56a52fb in  () at /usr/lib/xorg/modules/dri/nouveau_dri.so
#2  0x00007fffc56a5037 in  () at /usr/lib/xorg/modules/dri/nouveau_dri.so
#3  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 7 (Thread 0x7fffc7dea700 (LWP 17285)):
#0  0x00007ffff0df339d in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007ffff7662ac4 in  () at /usr/lib/libQt5Script.so.5
#2  0x00007ffff7662b09 in  () at /usr/lib/libQt5Script.so.5
#3  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#4  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 6 (Thread 0x7fffd1b0b700 (LWP 17284)):
#0  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#1  0x00007fffec0eabf9 in  () at /usr/lib/libglib-2.0.so.0
#2  0x00007fffec0ead0c in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#3  0x00007ffff1e57e7f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007ffff1dfe21a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#5  0x00007ffff1c2040a in QThread::exec() () at /usr/lib/libQt5Core.so.5
#6  0x00007ffff1c24cbd in  () at /usr/lib/libQt5Core.so.5
#7  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 5 (Thread 0x7fffd3bb3700 (LWP 17283)):
#0  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#1  0x00007fffec0eabf9 in  () at /usr/lib/libglib-2.0.so.0
#2  0x00007fffec0ead0c in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#3  0x00007ffff1e57e7f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
---Type <return> to continue, or q <return> to quit---
#4  0x00007ffff1dfe21a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#5  0x00007ffff1c2040a in QThread::exec() () at /usr/lib/libQt5Core.so.5
#6  0x00007ffff4d8f645 in  () at /usr/lib/libQt5Qml.so.5
#7  0x00007ffff1c24cbd in  () at /usr/lib/libQt5Core.so.5
#8  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#9  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 4 (Thread 0x7fffda319700 (LWP 17282)):
#0  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#1  0x00007fffec0eabf9 in  () at /usr/lib/libglib-2.0.so.0
#2  0x00007fffec0ead0c in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#3  0x00007ffff1e57e7f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007ffff1dfe21a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#5  0x00007ffff1c2040a in QThread::exec() () at /usr/lib/libQt5Core.so.5
#6  0x00007ffff4d8f645 in  () at /usr/lib/libQt5Qml.so.5
#7  0x00007ffff1c24cbd in  () at /usr/lib/libQt5Core.so.5
#8  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#9  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 3 (Thread 0x7fffdbd63700 (LWP 17281)):
#0  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#1  0x00007fffec0eabf9 in  () at /usr/lib/libglib-2.0.so.0
#2  0x00007fffec0ead0c in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#3  0x00007ffff1e57e7f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007ffff1dfe21a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#5  0x00007ffff1c2040a in QThread::exec() () at /usr/lib/libQt5Core.so.5
#6  0x00007ffff227ed45 in  () at /usr/lib/libQt5DBus.so.5
#7  0x00007ffff1c24cbd in  () at /usr/lib/libQt5Core.so.5
#8  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#9  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 2 (Thread 0x7fffe1e6c700 (LWP 17280)):
#0  0x00007ffff1d93800 in  () at /usr/lib/libQt5Core.so.5
#1  0x00007ffff147f6f0 in <signal handler called> () at /usr/lib/libc.so.6
#2  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#3  0x00007ffff65708e0 in  () at /usr/lib/libxcb.so.1
#4  0x00007ffff6572679 in xcb_wait_for_event () at /usr/lib/libxcb.so.1
#5  0x00007fffe43ddd49 in  () at /usr/lib/libQt5XcbQpa.so.5
#6  0x00007ffff1c24cbd in  () at /usr/lib/libQt5Core.so.5
---Type <return> to continue, or q <return> to quit---
#7  0x00007ffff0ded297 in start_thread () at /usr/lib/libpthread.so.0
#8  0x00007ffff153925f in clone () at /usr/lib/libc.so.6

Thread 1 (Thread 0x7ffff7e9ad80 (LWP 17279)):
#0  0x00007ffff152f2bd in poll () at /usr/lib/libc.so.6
#1  0x00007fffec0eabf9 in  () at /usr/lib/libglib-2.0.so.0
#2  0x00007fffec0ead0c in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#3  0x00007ffff1e57e7f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007ffff1dfe21a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#5  0x00007ffff1e06a74 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#6  0x000000000041cc32 in  ()
#7  0x00007ffff146c43a in __libc_start_main () at /usr/lib/libc.so.6
#8  0x000000000041cfaa in _start ()

dmidge, do you have any FolderView widgets on your desktop?

(In reply to Boian Berberov from comment #3)
> dmidge, do you have any FolderView widgets on your desktop?

Hi Boian,

Yes, I do. I have two folders. Are they the culprits?

(In reply to dmidge from comment #4)
> Yes, I do. I have two folders. Are they the culprits?

In my case they are.  I removed all FolderViews and rebooted (just restarting X didn't do it.)  Adding FolderViews back triggers high CPU usage, although not 100% in my case, but I am on openSUSE.  Try it; see if we have the same issue.

First stack trace is it rendering something, which is to be expected. 
The second is it just idling.

*** This bug has been marked as a duplicate of bug 378010 ***

Well, it may or may not be related to what Boian said, but I have a lot of identical messages:
file:///usr/share/plasma/plasmoids/org.kde.desktopcontainment/contents/ui/FolderItemDelegate.qml:282:17: QML Text: Binding loop detected for property "width"
Maybe it is one of the cause of the loop?

Not really related.a binding loop won't be infinitely looping.

Well, I don't think it is related to the folder view. In the meantime, I can't resize the folder view anymore.... :'(

I reopen this ticket with a bigger stacktrace.

Created attachment 106496 [details]
Several stacktraces of plasmashell

Btw, when I say the plasmashell takes 100%cpu, it is always above that. I guess one thread is taking 100%, the others take the normal amount, like around 10% fluctuating over time...

Trace shows it's processing an X event, which doesn't tell us much  - we're meant to be doing that.

There does seem an issue nvidia we've seen of Qt getting the framerate wrong and just constantly rendering instantly, 

If you're willing to build your own Qt from scratch and apply patches we can go somewhere with this.   Otherwise, not really.

*** This bug has been marked as a duplicate of bug 373368 ***

Ok, I understand.
However, I am willing to give a try. But I got to tell you: I've never done that before, and I may need some step by step instruction. I guess I should install qt5-base?

Hi again,

I am re-opening this ticket because I have some new information to provide.
I used to have a widget that displayed every second or so, the use of the CPU, the RAM&swap and the network. Thus, I guess it made a lot of refresh.

Removing that on the tray bar, I still have my CPU usage growing to 100% with plasmashell, but it is growing slowly. I can work with my computer for more than one hour without killing plasmashell just because I removed this widget. Before that, I needed to kill plasmashell under 5 minutes. So I guess there is something going on with the widget that refreshes a lot the display of the tray bar and the increasing CPU usage of plasmashell.
(Because now, the CPU usage of plasmashell grows linearly over time, until I kill it and restart it. It was probably the case before but I didn't have time to notice it.)

Funny thing is: it used not to happen to me with the plasmashell and nouveau version that were 1 year old.
Now, my plasma-workspace version is 5.10.5-4 and xf86-video-nouveau is 1.0.15-2.

Please ask me if you need further information. :o)

Cheers!

I am experiencing high CPU usage after plasma has been up for a bit. This occurs in a vm and on Intel Atom modesetting set up. I do not experience this issue on my desktop where opengl is available. I tried explicitly setting xrender though I know this is now merely a suggestion and did not observe any changes. I'll try rebooting as soon as I can as see if that helps any. My target needs to have a long uptime so rebooting every so often is not an option.

Qt Version: 5.9.2
Frameworks Version: 5.39.0
Operating System: Linux 4.13.7-gentoo x86_64
Distribution (Platform): Gentoo Packages

After update Fedora 26 to 27, plasmashell use above 80% CPU. I delete all FolderView widgets. High CPU become periodic. In this video, you can see that the normal loading can be resize panel and restart plasmashell. After a reboot, a high CPU load can return and is normalized by resizing the panel and restarting plasmashell:
https://youtu.be/B1xib6bHUOg

If the panel is not resize, a multiple restart of the plasmashell does not result in a high CPU load:
https://youtu.be/Af6FctBcZcg

When the ffmpeg does not work, CPU utilization is more than 80%:
https://photos.app.goo.gl/3rY6yRDwiMz5nNy32
PlasmaShell version 5.10.5

(In reply to Oleg from comment #16)
> PlasmaShell version 5.10.5

In plasmashell 5.11.3 this problem present.

>I am re-opening this ticket because I have some new information to provide.

Thanks, I did read it.

I can't do much else with this, we have N similar reports of "slow CPU " whcih is a very vague symptom. This "see also" section of the linked reports tracks specific technical areas.

*** This bug has been marked as a duplicate of bug 378010 ***