Tail-PASS: Resource-Based Cache Management for Tiled Graphics Rendering Hardware

摘要

Modern graphics rendering is a very expensive process and can account for 60% of the battery consumption on current games. Much of the cost comes from the high memory bandwidth of rendering complex graphics. To render a frame, multiple smaller rendering passes called scenes are executed, with each one tiled for parallel execution. The data for each scene comes from hundreds of software resources (textures). We observe that each frame can consume up to 1000s of MB of data, but that over 75% of the graphics memory accesses are to the top-10 resources, and that bypassing the remaining infrequently accessed (tail) resources reduces cache pollution. Bypassing the tail can save up to 35% of the main memory traffic over resource-oblivious replacement policies and cache management techniques. In this paper, we propose Tail-PASS, a cache management technique that detects the most accessed resources at runtime, learns if it is worth bypassing the least accessed ones, and then dynamically enables/disables bypassing to reduce cache pollution on a per-scene basis. Overall, we see an average reduction in bandwidth-per-frame of 22% (up to 46%) by bypassing all but the top-10 resources and an 11% (up to 44%) reduction if only the top-2 resources are cached.