Display Subsystem Sequential Compositing for GPU Load Reduction

The patent segments the compositing task from the GPU by introducing a dedicated display subsystem with hardware layers. The GPU handles only rendering while the display subsystem handles compositing through sequential layer composition, thus separating these two functions to avoid GPU overload and maintain both compositing quality and rendering performance.

The patent introduces an intermediate frame buffer as a mediator between the GPU rendering output and the final display output. This intermediate frame allows the GPU to complete rendering independently while the display subsystem performs compositing operations separately, enabling asynchronous operation and preventing the GPU from being blocked by compositing tasks.

The patent implements periodic action by sequentially reusing the same hardware layers for compositing multiple window surfaces across different time periods. Instead of requiring simultaneous availability of multiple hardware layers, the system composites surfaces one after another using the same hardware resources, thus reducing hardware complexity while maintaining the ability to handle multiple surfaces.

The patent transitions from a spatial dimension approach (using multiple hardware layers simultaneously) to a temporal dimension approach (sequentially reusing hardware layers over time). This dimensional change allows the system to composite more surfaces than the number of physical hardware layers by utilizing time multiplexing, effectively increasing the number of composited surfaces without increasing hardware complexity.