Hardware acceleration for Window systems

Graphics pipelines are quickly evolving to support multitasking workstations. The driving force behind this evolution is the window system, which must provide high performance graphics within multiple windows, while maintaining interactivity. The virtual graphics system presented by 7 provides a clean solution to the problem of context switching graphics hardware between processes, but does not solve all the problems associated with sharing graphics pipelines.The primary difficulty in context switching a graphics accelerator is the pipeline latency encountered during a pipeline flush. This latency removes the responsiveness and interactivity of the graphics system. As primitives become more complex and pipelines become longer, pipeline latency grows. Hardware solutions are described which further accelerate the window system by eliminating the need for pipeline flushing and resynchronization. An overview of the entire system is presented, highlighting the hardware mechanisms which contribute to window acceleration.