https://bugs.freedesktop.org/show_bug.cgi?id=106175
--- Comment #53 from bmilreu@gmail.com --- (In reply to rropid from comment #45)
(In reply to bmilreu from comment #43)
If devs want an easy test case, use these links for reproducing it in chromium:
https://www.vsynctester.com/ https://www.testufo.com/photo https://www.slither.io
move the cursor around, move/resize some windows. you will notice it
the vsync/cursor stutters and frame-skips are pretty noticeable with dc=1 on all three links
KWin, compton, TearFree, mutter, xfwm4 all have the same problems.
I just tried dc=1 and I only seem to have a problem if I use TearFree. Things are totally fine without TearFree.
To be clear about what I'm doing here right now:
I made sure DC is enabled:
$ systool -vm amdgpu | grep dc dc = "1" $ dmesg | grep -i display [ 1.014297] [drm] Display Core initialized with v3.1.59!
I removed TearFree from my X config:
$ cat /etc/X11/xorg.conf.d/20-amdgpu.conf Section "OutputClass" Identifier "my amdgpu settings" MatchDriver "amdgpu" Option "DRI" "3" EndSection
And I started Compton like this to make sure it's a clean config:
$ compton --config /dev/null --backend glx --vsync opengl
With this setup, I don't seem to have any stutter. I visited the websites you mention in a Chromium window, then opened another window and tried moving things around and resizing. It behaves fine, same as what I know from normally using dc=0.
Kernel is 4.19.2, Mesa 18.2.4, Xorg 1.20.3, the GPU is a RX480, monitor is 60 Hz.
After I had typed this, I have now added TearFree to the X config and restarted X:
$ cat /etc/X11/xorg.conf.d/20-amdgpu.conf Section "OutputClass" Identifier "my amdgpu settings" MatchDriver "amdgpu" Option "TearFree" "true" Option "DRI" "3" EndSection
Now, with TearFree enabled, things are super terrible. Trying to move a window around has extreme stutter, it seems to drop frames. If I restart Compton with "GALLIUM_HUD=fps" and then try moving a window around in circles, I can see it stays below 40 fps instead of hitting the 60 fps that it should be running at.
"compton --vsync opengl" is a case less/not affected by this in my setup, try --vsync opengl-swc, --vsync opengl-oml or --vsync opengl-mswc
Also try other compositors. Kwin, mutter, xfwm4