Bug 343773 - kwin_x11 does not paint windows, uses 100% CPU in OpenGL mode, under NVidia Legacy driver 304, GeForce 7025 / nForce 630a
Summary: kwin_x11 does not paint windows, uses 100% CPU in OpenGL mode, under NVidia L...
Status: RESOLVED DUPLICATE of bug 343551
Alias: None
Product: kwin
Classification: Plasma
Component: compositing (show other bugs)
Version: 5.2.0.1
Platform: Slackware Linux
: NOR major
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2015-02-04 13:57 UTC by sombragris
Modified: 2015-05-09 01:37 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In:


Attachments

Note You need to log in before you can comment on or make changes to this bug.
Description sombragris 2015-02-04 13:57:15 UTC
Hi,

I use a motherboard whose video chip identifies in lspci as GeForce 7025 / nForce 630a. I have to use the latest nVidia 304.125 legacy driver, because the nouveau driver is not an option (random hard lockups/freezes).

If the rendering engine in KWin is one of the OpenGL variants (2.1, 3.0), Plasma starts but doesn't complete the startup sequence. Looking at htop shows that a process identified as kwin_x11 consumes 100% of CPU.

Killing kwin_x11 gives a desktop without window manager. I can open applications, but all of them without window decorations and uniformly placed at the top left corner of screen.

Changing the rendering engine to XRender works around the problem and gives me an usable desktop.

Thank you, 

Eduardo

Reproducible: Always

Steps to Reproduce:
1. Select any kind of OpenGL rendering for KWin.
2.
3.

Actual Results:  
Kwin does not show at startup, uses 100% of CPU.

Expected Results:  
Kwin should start and work properly.
Comment 1 Thomas Lübking 2015-02-04 14:30:26 UTC
please try
 KWIN_EXPLICIT_SYNC=0 kwin_x11 --replace &
to confirm the duplicate.

*** This bug has been marked as a duplicate of bug 343551 ***
Comment 2 sombragris 2015-02-04 17:31:45 UTC
Trying KWIN_EXPLICIT_SYNC=0 kwin_x11 --replace & and got the following results:

a) With XRender: No change.
b) With OpenGL 3.1: limited desktop effects, some rendering artifacts (metallic grey on transparent surfaces, etc), but otherwise it works.
c) With OpenGL 2.0: Works, all desktop effects function, rather slow but OK.

b) and c) were observed with GLX as rendering interface.

Thank you for the suggestion. How can I enable this so kwin would start this way every time by default?
Comment 3 Thomas Lübking 2015-02-04 18:04:31 UTC
adding a file ~/.config/plasma-workspace/env/kwin.sh with the content

#!/bin/sh
export KWIN_EXPLICIT_SYNC=0

should do.

Don't forget to make is executable
    chmod +x ~/.config/plasma-workspace/env/kwin.sh

NOTICE:
that I don't know whether this path will change in future (the startkde script has some unspecific comment about this)

Nvidia does not support egl on X11 atm (and I doubt the legacy driver ever will)
Speed could be driven by misdetected triple buffering support, bug #343184
Comment 4 sombragris 2015-02-05 11:24:51 UTC
Thank you Thomas!
Comment 5 adlo 2015-05-09 01:37:55 UTC
This bug still seems to exist in Plasma 5.3 on Arch Linux.