High CPU usage in Wayland Arch Linux.

mokh

Hello everyone, I have a small issue that I need help with. When I set a fixed size for my Qt5 Python app, I notice higher CPU usage than usual, between 10% and 12%. However, if I don't fix the window size, the CPU usage is normal.

I tracked down the problem to the Qt platform on Wayland. If I switch to using xcb by setting the environment variable QT_QPA_PLATFORM=xcb, I don't face this issue.

Here's a minimal example that causes the problem:

import sys
from PyQt5.QtWidgets import QApplication, QWidget

if __name__ == "__main__":
    app = QApplication(sys.argv)

    window = QWidget()
    window.setWindowTitle("High CPU usage in Wayland on Arch Linux")
    
    # Set the fixed size of the window
    window.setFixedSize(800, 600)  # Width: 800, Height: 600

    window.show()

    sys.exit(app.exec_())

If anyone has encountered this issue or knows a potential workaround, I would greatly appreciate your help.

Thank you!

SGaist

Hi and welcome to devnet,

Do you experience the same issue with PySide6 ?

Which desktop environment are you using ?
Which version of Wayland ?

mokh

Hey and thank you,

Yes i tried the same program with PySide6 and had the same issue and it gets fixed when I change the Qt platform from Wayland to XCB.

For the desktop environment I am on Hyperland and I am using the 1.22.0-1 version of Wayland.

Hope that helps.