Slow rendering with DRI3, intel and rotate monitor in webki2gtk
Submitted by Jan Burgmeier
Assigned to Xorg Project Team
Link to original bug (#107665)
Description
Created attachment 141251 XOrg log
Hi,
I'am experincing very slow rendering in webki2gtk on webpages using accelerated rendering. For example while using LIBGL_DEBUG=verbose mini-browser I can see that for https://www.webkitgtk.org/ no GL is loaded and it is fast and for https://www.google.com GL is loaded and typing text in the textfield is very slow. The slow rendering only occurs if one monitor in a two monitor setup is rotated. As soon as the rotation is unset the slowdown is gone, no restart of mini-browser needed. If mini-browser is started with LIBGL_DRI3_DISABLE=true the slowdown is also gone.
The intel DDX driver or modesetting on radeon does not have this problem.
I found bug #85064 but in the webkit2gtk version I use this should already be fixed.
Environment: Kernel: 4.14.39 Mesa: 18.1.6 and git master XOrg: 1.20.1 Webkit2gtk: 2.20.2 Screen: Dual monitor one rotated
Attachment 141251, "XOrg log":
Xorg.0.log
Version: git