 **Description:** In KDE Plasma Wayland, kwin\_wayland's rendering for the desktop is limited to a maximum of 60FPS in single monitor mode. This limitation can cause framedrops, especially when the GPU is under load from other applications. **Test Video:** [https://youtu.be/xVU9KCHwsgA](https://youtu.be/xVU9KCHwsgA) **Unexpected Behavior:** Connecting an external monitor, even a 60Hz monitor, can unexpectedly cause kwin\_wayland to render at 120FPS. However, this behavior is not consistent and should not be considered a solution. **Impact on User Experience:** The 60FPS rendering limit in single monitor mode can lead to: * Framedrops * Choppy animations * Laggy scrolling * Reduced responsiveness **Test Environment:** * **Operating Systems:** * Debian (kernel 6.8.6) with Plasma 5 (5.27.5) * Arch Linux (kernel 6.8.8) with Plasma 6 (6.0.5) * **GPU:** * Intel i7-8650U (HD620 graphics) * **Displays:** * **Laptop Display:** * Model: Surface Book 2 15" * Resolution: 3240x2160 * Refresh Rate: 59.995 Hz * **External Monitor:** * Connection: USB-C adapter and VGA cable * Model Number: VS11234 * Resolution: 1400x1050 * Refresh Rate: 59.978 Hz * H.frequency: 65KHz * V.Frequency: 60Hz * Pixel clock: 122MHz **Test Scenarios:** 1. **Idle Desktop (Debian):** * Observe kwin\_wayland rendering behavior and frame rate. 2. **Playing YouTube Video in Playing YouTube Video in Picture-in-Picture mode (Arch Linux):** * Observe kwin\_wayland rendering behavior and frame rate. 3. **Playing osu! Game (Arch Linux):** * Observe kwin\_wayland rendering behavior, frame rate, and any performance issues. **Tools Used:** * Plasma FPS monitor * Intel\_gpu\_top (for monitoring GPU usage) **Test Procedure:** 1. Connect the external monitor to the laptop. 2. Observe the frame rate, GPU usage, and any visual anomalies. 3. Disconnect the external monitor. 4. Observe the frame rate, GPU usage, and any performance changes. 5. Reconnect the external monitor. 6. Observe the frame rate, GPU usage, and any visual changes. **Observations:** * When the external monitor is connected, kwin\_wayland renders at 120FPS. * Disconnecting the external monitor reverts kwin\_wayland to 60FPS rendering, causing framedrops in all applications. * Reconnecting the external monitor resumes 120FPS rendering. **Tried Solution** 1. Restart 2. [Force to render 120FPS by modifying \~/.config/kwinrc](https://www.reddit.com/r/kde/comments/ix3j51/applications_not_running_at_120hz_even_after/) **Conclusion:** The current behavior of kwin\_wayland limiting the frame rate to 60FPS in single monitor mode, while unexpectedly switching to 120FPS with an external monitor. **Proposed Solution:** * Allow kwin\_wayland to render at a higher frame rate in single monitor mode, even if the display is only 60Hz. This would provide users with a smoother visual experience and more control over their desktop performance. **Further Explanation:** The unexpected 120FPS rendering with an external monitor suggests kwin\_wayland is capable of exceeding the 60FPS limit. A user-selectable option to raise the frame rate cap would be beneficial.
You have a 60Hz screen, so KWin renders 60 frames a second. With two 60Hz screens, it renders in total 120 times a second. This is completely expected, and the fps effect is just a bit misleading there. > Allow kwin\_wayland to render at a higher frame rate in single monitor mode, even if the display is only 60Hz. This would provide users with a smoother visual experience and more control over their desktop performance. Rendering twice the frames and throwing away half of them doesn't really help, it just hurts performance and increases power usage. If you experience stutter or frame drops though, that is a bug we can look at. Before reporting it however, please wait for the 6.1 release and test the performance of that, because it contains a lot of performance fixes, specifically for Intel integrated GPUs.
(In reply to Zamundaaa from comment #1) > You have a 60Hz screen, so KWin renders 60 frames a second. With two 60Hz > screens, it renders in total 120 times a second. This is completely > expected, and the fps effect is just a bit misleading there. > > > Allow kwin\_wayland to render at a higher frame rate in single monitor mode, even if the display is only 60Hz. This would provide users with a smoother visual experience and more control over their desktop performance. > Rendering twice the frames and throwing away half of them doesn't really > help, it just hurts performance and increases power usage. > > If you experience stutter or frame drops though, that is a bug we can look > at. Before reporting it however, please wait for the 6.1 release and test > the performance of that, because it contains a lot of performance fixes, > specifically for Intel integrated GPUs. I understand that it's completely normal to render at 60fps, that's why I was hesitated to report this issue. But I didn't expect this issue affects applications as well, like it had shown in the testing video, I thought it was the desktop plasmashell only.. Osu! was set to unlimited framerates, but osu! and other applications are also affected by this kwin render limitation. Even if I set it to fullscreen, the issue persisted. I only discovered this issue when I unplugged the 2nd display, I've been using dual screen since the beginning. I would love to see how plasma 6.1 works, since this issue is affecting stable plasma 5.27 as well.
(In reply to Curie from comment #2) > (In reply to Zamundaaa from comment #1) > > You have a 60Hz screen, so KWin renders 60 frames a second. With two 60Hz > > screens, it renders in total 120 times a second. This is completely > > expected, and the fps effect is just a bit misleading there. > > > > > Allow kwin\_wayland to render at a higher frame rate in single monitor mode, even if the display is only 60Hz. This would provide users with a smoother visual experience and more control over their desktop performance. > > Rendering twice the frames and throwing away half of them doesn't really > > help, it just hurts performance and increases power usage. > > > > If you experience stutter or frame drops though, that is a bug we can look > > at. Before reporting it however, please wait for the 6.1 release and test > > the performance of that, because it contains a lot of performance fixes, > > specifically for Intel integrated GPUs. > > I understand that it's completely normal to render at 60fps, that's why I > was hesitated to report this issue. > > But I didn't expect this issue affects applications as well, like it had > shown in the testing video, I thought it was the desktop plasmashell only.. > > Osu! was set to unlimited framerates, but osu! and other applications are > also affected by this kwin render limitation. > Even if I set it to fullscreen, the issue persisted. > > I only discovered this issue when I unplugged the 2nd display, I've been > using dual screen since the beginning. > > > I would love to see how plasma 6.1 works, since this issue is affecting > stable plasma 5.27 as well. I also think use more power to render at higher framerates is reasonable. As you can see in the testing video, osu! cannot stable at 60fps when it was locked to 60fps. When the 120fps limitation releases, it immediately increase fps up to 110fps, so the gpu is capable to do 60fps stable, something is off.
(In reply to Curie from comment #3) > As you can see in the testing video, osu! cannot stable at 60fps when it was > locked to 60fps. > When the 120fps limitation releases, it immediately increase fps up to > 110fps, so the gpu is capable to do 60fps stable, something is off. That sounds like you just have vsync enabled in osu! and with that the GPU isn't running as fast as it should be. You can make osu! run at a faster refresh rate by just disabling vsync in the game