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Wild Penguin

Member

Registered: 2015-03-19

Posts: 347

Plasmashell uses a lot of CPU (since recent-ish)

Hi!

After some upgrade, maybe for a month or so, I've noticed abnormally high CPU usage in plasmashell.

When being idle, it just consumes 1-2 full CPU cores. It doesn't affect my workflow that much since I have many many cores, but sure does consume electricity and generate heat (and it's summertime).

This is one of those things I've been hoping will be fixed by some upgrade later.

In "htop" I can see `plasmashell --no-respawn` -processes, currently three of them, consuming ~60% of CPU cycles each. The desktop never gets to (near) 0% CPU usage as it used to. Sometimes there are 1-2 processes each consuming 100%. It can just *sometimes* get to near 0% for a (literal) minute, until it starts hiking again.

Moreover, more often than not plasmashell crashes when I log in. There will be the crash handler which I promptly close. I'm not sure it's related, I think I've seen this abnormal usage even when the crash handler is not there on startup.

Obvious thing to do is to log in with a fresh user account, however does not work around the issue I would need to redo all my settings (and find out how to reset Plasma 6 configuration in my real home directoty, which is scattered all around the home directory, last time I checked).

Is this a common issue? Other KDE Plasma users with similar experiences?

Cheers!

seth

Member

Registered: 2012-09-03

Posts: 60,801

Re: Plasmashell uses a lot of CPU (since recent-ish)

Did you move from plasma/x11 to plasma/wayland w/ the 6.0 udpate? Also an issue w/ plasma/x11?

There will be the crash handler which I promptly close.

Ok, but the backtrace might be useful here.

I can see `plasmashell --no-respawn` -processes, currently three of them

Processes or threads?

Obvious thing to do is to log in with a fresh user account, however does not work around the issue

For clarification: you tried a fresh user account and it resulted in the exact same condition?

Wild guess: nvidia, kms not enabled and you're software rendering on the simpledrm device?

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Wild Penguin

Member

Registered: 2015-03-19

Posts: 347

Re: Plasmashell uses a lot of CPU (since recent-ish)

Hi Seth,

Thanks for the reply!

This is on X11. It's plasmashell processess (different PIDs).

I think I've noticed the cuplrit: it's system monitor widgets take a lot of CPU. If I change the workspace to one where there are none, the CPU usage goes down (the processes disappear). I don't think they used this much CPU before, and although one  could argue they are unnecesary eye candy, they are just taking in some numerical values and
rendering a picture!

Yesterday I noticed I can not open these widget's settings anymore; it opens but it is an empty window.

I'll do some tests and report back to make sure what is going on.

Cheers!

p.s. I don't use Wayland since it still has multitude of bugs which Plasma on X.Org does not have, which severely affect my workflow. Some input related bugs have been fixed, some are still there (keyboard layout and shortcut handling does not work properly), and session restoring does not work properly.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 23,895

Re: Plasmashell uses a lot of CPU (since recent-ish)

The sensors widget code was heavily rewritten at some point in the later plasma 5 releases, there is/was some auto-converter for existing widgets, but it'd be generally a good idea to remove and recreate them so that they cleanly use the newer code (... and in any case, they have routinely been the cause of issues like these, you might want to keep them off regardless...)

Wild Penguin

Member

Registered: 2015-03-19

Posts: 347

Re: Plasmashell uses a lot of CPU (since recent-ish)

Hmm,

Thanks V1del, I will remove them for now.

I've also noticed that even if I *do* have them on the desktop, sometimes the CPU usage goes down (and they function as they always did). So I'm not sure what is going on.

But it should be easy to test if the issue goes away by removing them.

Stay tuned!