We are using TI Sitara AM33 system on chip with 600 Mhz clock and 256 Mb ram. OS is OE Yocto v2.1 Krogoth, kernel 4.4.19. Video driver - DRM/KSM
We are having issues with mouse performance.
I have made a little vedio to demonstrate the effect: https://www.youtube.com/watch?v=5dRDGzhcnn0
Note how mouse pointer is moving smoothly on the blank area of the window and lags over at controls. It's as if it is going through jelly. If you have more controls on the window, mouse becomes so laggy, it's unusable. CPU load is minimal though.
There could be no error in the example app in the vedio - we created a blank QT Widget project, put the controls on the form and that's it, it is not doing anything else at all.
Has anyone seen such mouse issues?
If you're not using an X server, then you need to check what platform plugin is Qt using on your platform. Perhaps that plugin is broken or not the best choice in your situation.
Your application is also very unlikely to use GPU in any capacity other than to composite the windows (if at all), so the CPU load being low is rather telling.
It seems as if the event dispatch system on your platform was very slow the more widgets there are. This is unlikely to have much to do with the graphics side of things. In a process of elimination perhaps you could first benchmark the performance of synchronization primitives (
QBasicMutexandQMutex) and atomic integers and pointers to ensure that they are configured correctly for your platform.