Hi abha,
To get optimal performance when running a GLES application in X11 you need one of the following:
- The application is configured to run in full-screen and is a top-level window (i.e., there will be a large performance impact if another window is rendered on top)
- The window manager is a GLES-compatible compositing window manager
Understandably it is not always possible/desirable to run applications in full-screen mode so the practical option is to use a compositing window manager. To my knowledge only Compiz (certain branches), KWin (4.x), Mutter (the GNOME 3's default window manager which is used by GNOME shell) and Ubuntu's Unity (which uses a modified version of Compiz) support compositing in GLES mode.
The main reason for the performance impact is because the armsoc driver doesn't make use of hardware blitter (which might not be present in an SoC) to transfer rendered frames from GPU to X11 windows. As a result all frames rendered using the GPU will have to be converted and copied to X11 windows using CPU. Using a GLES compositing window manager avoids this issue where the X11 window content is stored and rendered as a texture. In a non-composited environment the Mali driver takes a shortcut and renders directly to the display frame buffer -bypassing most of X11's processing- if it detects a full-screen, top-level GLES window.
Best regards,
Tu