Halved refresh rate on topmost GPU monitors in dual-GPU desktop setup
Affected version
- Fedora Silverblue 38
- Mutter 44.2
- Both Xorg and Wayland
Bug summary
When running displays in a certain configuration, those on the topmost GPU will behave as if the refresh rate has been halved.
There are no such issues when all the displays are on one GPU or the other.
Steps to reproduce
- Have two dedicated GPUs
- Connect both to your motherboard
- Two (or more) displays, with at least one on each GPU
- Run any software, or move the cursor around, and watch as the monitor(s) on the topmost GPU feels laggy and software behaves as if the refresh rate is halved
What happened
Mutter (both in Xorg and Wayland) had the displays on the topmost GPU behave as if their refresh rate was halved.
What did you expect to happen
Mutter (on Wayland) would treat the topmost GPU displays as it usually would.
Relevant logs, screenshots, screencasts etc.
Full system information:
- Fedora Linux 38.20230713.0 (Silverblue)
- GNOME 44.2
- AMD Ryzen 5 1600
- MSI B450 Tomahawk (NOT MAX)
GPUs:
- Top-most: AMD Radeon RX 5500XT (8GB)
- Bottom-most: AMD Radeon RX 560 (4GB)
KDE Plasma (5.27, Xorg) has no such issues, however it runs all the software on the topmost GPU at the highest refresh rate out of all monitors. This is expected. It will not boot into Wayland, however, only gives a black screen.
Edited by Dallas Strouse