A distributed snooping algorithm for pixel merging

Previous pixel-merging algorithms have required special-purpose networks, and use more network bandwidth than is necessary. We developed an algorithm that merges pixels on shared-memory bus multiprocessors, using an existing bus. Analysis and simulations suggest that it uses less bus bandwidth than other algorithms. We based our algorithm on the snooping cache-coherency protocols on which a number of shared-memory multiprocessors have been based. In these architectures, each processor keeps its cache consistent with other processors' memories by listening (snooping) on a shared bus over which memory updates are written. Snooping maintains consistent globally shared memory. This algorithm assists graphics rendering by letting processors compare pixel values and delete those pixels that do not contribute to the final image. This reduces network bandwidth requirements and eliminates the need for a special-purpose network.<>