Intel's Mesa Drivers Enable "TBMIR" Tile-Based Rendering
This tile-based immediate mode rendering (TBIMR) functionality works with Intel Gen12.5 graphics and newer. This Mesa code has been successfully tested on DG2/Alchemist Arc Graphics as well as upcoming Meteor Lake integrated graphics.
The merge request explains of TBIMR:
"This series introduces the basic driver infrastructure required to take advantage of the tile-based immediate mode rendering (TBIMR) functionality of current Intel platforms (DG2 or MTL are currently supported). Current platforms have a tile sequencer hardware sitting between primitive setup and rasterization, which is able to buffer triangles (and some state setup commands like push constants) in batches as they're processed by the geometry stages. A tile walk can be triggered by various conditions (typically transparently by the hardware when the batch fills up or there is a pipeline stall due to a data dependency), which replays the batch repeatedly dispatching the buffered geometry to the rasterizer one tile at a time."
Where it gets exciting is the performance benefits for memory bandwidth bound workloads:
"... which can reduce bandwidth usage by 10% to 30%, which can improve performance in memory bandwidth-bound workloads that are able to buffer enough primitives for the rasterization reordering to be effective. The Aztec Ruins benchmark (either VK or GL) is particularly effective illustrating this: At 4K with high settings it improves by about ~13% with TBIMR enabled on Arc A750 (improvement is over 16% on MTL), but the improvement drops to about 0% at 1080p, since the benchmark becomes mostly CPU-bound at lower resolution, so reducing bandwidth consumption isn't guaranteed to improve performance."
This TBIMR tile-based rendering for Gen12.5+ graphics is now in Mesa 24.0-devel for Intel Iris Gallium3D and ANV Vulkan drivers ahead of the stable debut in Q1.
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