The patent's inventor is Minkin, Alexander L. (
This patent was filed on
From the background information supplied by the inventors, news correspondents obtained the following quote: "The present invention relates generally to graphics processors and more particularly to fast context switching that reduces the loss of in-progress processing work.
"Computer applications or programs running on a computing platform typically generate images for display on a monitor. The images may be a program output, for example a scene from a video game, they may provide an input to a program, or they may be some combination of these, such a document created using a word processing application.
"These images appear in a window on the monitor. The window may be larger, smaller, or the same size as the display monitor. Commonly, users have several windows open simultaneously, some or all of which may be at least partially visible at any given time. Each of these windows may also be referred to as a context.
"Each application or program can include drivers, modules, and other software routines. Also, they may utilize other software that may be available on the computing platform. A graphics processor uses these tools to generate individual pixels of an image that appears on the monitor. When multiple windows or contexts are open, the graphics processor may work on generating pixels for a first window or context, then it may switch to generating pixels for a second window or context. This is referred to as a context switch.
"It is desirable to be able to switch from one context to another quickly. When a graphics processing circuit is instructed or otherwise determines that a context switch should occur, delay in performing the switch reduces graphics system performance. In particular, 3-D images may be degraded. However, switching from one context to another too quickly can waste processing power by deleting or otherwise not using processing work that is in progress.
"Thus, it is desirable to be able to perform a context switch quickly while not wasting a significant amount of in-progress work."
Supplementing the background information on this patent, VerticalNews reporters also obtained the inventor's summary information for this patent: "Accordingly, embodiments of the present invention provide circuits, methods, and apparatus that perform a context switch quickly while not wasting a significant amount of in-progress work.
"An exemplary embodiment of the present invention provides a cutoff point or stage in a texture pipeline. After receipt of a context switch instruction, texture requests and state updates that have progressed beyond the cutoff point are processed before the context switch is completed, while those above the cutoff point are not processed, but instead are stored in a memory. After the texture requests and state updates below the cutoff point are processed, global states in the texture pipeline can also be stored in the memory. This memory may be a frame buffer in a system or graphics memory, or it may be another memory. A second context may then be restored by loading its last global states into the texture pipeline, then reading its texture requests and state updates from the memory and providing them to the texture pipeline.
"In particular, one specific embodiment of the present invention uses a first-in-first-out memory (FIFO), referred to here as a replay FIFO, or other local memory to store recent texture requests and state updates, that is, those requests and updates that have yet to reach the cutoff point in the texture pipeline. Another local memory stores a copy of the global states used the texture pipeline. When a context switch instruction is received, texture requests and state updates that have progressed beyond the cutoff point continue to be processed, while the contents of the FIFO are not processed, but stored in a second memory, such as a system or graphics memory. Once the texture requests and state updates below the cutoff point have been processed, the latest global states can be written from the local memory to the second memory. A second context can then be restored by reading the second context's global states, texture requests, and state updates. The global states should be restored the texture pipeline before processing begins in the texture pipeline. The global states can be loaded into the texture pipeline directly, or they may be rewritten to the global state memory, a second global state memory, or other appropriate circuit, before being loaded into the texture pipeline. The texture requests and state updates can then be provided to the texture pipeline. The texture requests and state updates can also be loaded into the texture pipeline directly, or they may be rewritten to the replay FIFO, a second FIFO, or other appropriate circuit. Processing of the second context can then continue.
"The location of the cutoff point can be determined during design or dynamically during device operation. For example, the cutoff point may be a stage in the texture pipeline where it is known that once a texture request has reached that stage, it cannot result in a page fault. Alternately, other criteria may be used in determining the cutoff point. Various embodiments of the present invention may incorporate any of these or the other features described herein.
"A better understanding of the nature and advantages of the present invention may be gained with reference to the following detailed description and the accompanying drawings."
For the URL and additional information on this patent, see: Minkin, Alexander L.. Texture Pipeline Context Switch. U.S. Patent Number 8817035, filed
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