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Desktop freeze when using V-Sync


Description Dmitriy 2019-01-06 15:05:11 CET
Desktop freeze when using V-Sync, when I leave the computer for N time. This problem I have once, a long time ago, and reappeared when switching to the 4.20 kernel.

OS: Arch,  drivers: amdgpu + mesa

xfwm4 --version

	This is xfwm4 version 4.12.5 (revision d730ebb6) for Xfce 4.12
	Released under the terms of the GNU General Public License.
	Compiled against GTK+-2.24.32, using GTK+-2.24.32.

	Build configuration and supported features:
	- Startup notification support:                 Yes
	- XSync support:                                Yes
	- Render support:                               Yes
	- Xrandr support:                               Yes
	- Embedded compositor:                          Yes
Comment 1 Olivier Fourdan editbugs 2019-01-07 09:17:32 CET
Unfortunately, the so called "v-sync" in the xfwm4 compositor up to and including version 4.12 was a (bad) joke and has never actually worked.

Newer (4.13+) versions implements a much better mechanism using either Xpresent or GLX to prevent tearing.

So long story short, you can disable the old v-sync it's useless and won't work anyway, not something I'm going to fix in older version since it's dead code nowadays.
Comment 2 Dmitriy 2019-01-07 13:57:21 CET
Worked for me, but hangs the system. But I understand you, I will wait for a stable release.
Comment 3 Dmitriy 2019-01-08 21:53:44 CET
I put myself a devel branch, but I did not find where to enable v-sync.
Comment 4 Olivier Fourdan editbugs 2019-01-09 08:50:45 CET
That's normal, there is no point in having a user setting to "unbreak" the code...

Basically, if you have Present available, it will use that, failing that, if you built with GLX, it will use GL and failing that, then no V-Sync is available.

What's enabled at build time can be seen either in the configure logs or by invoking "xfwm4 --version".

Last, if you *really* want to change the defaults for v-sync, there's an xfconf key for that:

 Default: xfconf-query -c xfwm4 -p /general/vblank_mode -s "auto"
 XPresent: xfconf-query -c xfwm4 -p /general/vblank_mode -s "present"
 GLX: xfconf-query -c xfwm4 -p /general/vblank_mode -s "glx"

Note that the key will have no effect if a given v-sync method wasn't enabled at build time, of course.
Comment 5 Dmitriy 2019-01-09 10:17:10 CET
Thank you, judging by the video it works.

Bug #15026

Reported by:
Reported on: 2019-01-06
Last modified on: 2020-05-28


Olivier Fourdan
CC List:
1 user




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