Irregular FPS with Path of Exile, Wayland and dynamic-max-render-time
Affected version
OS: Ubuntu 23.04
Mutter: 44.0 and main as of today
Wayland
Bug summary
I'm having a strange issue with the game Path of Exile (free). With Ubuntu Gnome Wayland session, vsync on in the game, I get very irregular frame rates, it jumps around 40 fps. If I switch to Plasma Wayland the game is very smooth at 60 fps.
I'm running the game from Steam with Proton. I've tried Proton 7.0 and Proton 8.0 so far, no difference. The game uses Vulkan so I guess it's being allowed to set up all the swap and presentation stuff pretty much itself... ?
MUTTER_DEBUG_DISABLE_TRIPLE_BUFFERING=1 doesn't help Mutter so it's not related to triple buffering, which makes sense since it's a full screen game anyway.
Mesa: 23.2.0 and 23.1-rc Kernel: 6.2.0-1003-lowlatency GPU: Radeon 6800 XT Monitor resolution: 4K CPU: Ryzen 9 5900X
Steps to reproduce
Start Path of Exile on Steam. Set the Vulkan backend and Vsync on.
What happened
We discussed if there was anything Ubuntu specific here, and concluded that it was not: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2016990
It turns out that setting CLUTTER_PAINT=disable-dynamic-max-render-time works around the problem.
I also tried compiling mutter from main now, still same problem.