Metal 2 on A11 — Overview

Tech Talks

Metal 2

• GPU-driven rendering
• Platform feature alignment
• Machine learning acceleration
• Advanced optimization tools

Classical GPU Architecture

TBDR GPU Architecture

A11 GPU Architecture

Accelerated Rendering Techniques

• Deferred Rendering
• Tiled Forward
• Order Independent Transparency
• Multi-Layer Alpha Blending
• Sub-Surface Scatter
• MSAA Tone-mapping
• Custom Resolves
• Surface Aggregation

Metal 2 on A11

Advancing the TBDR Architecture

• Imageblocks
• Tile Shaders
• Imageblock Sample Coverage Control
• Raster Order Groups
• Threadgroup Sharing

Imageblocks

• 2D data structure accessible from shaders
  - Single pixel access from fragment functions
  - Full access from kernel functions
• Multi-plane layout
  - Efficient bulk store pixels to textures
• Supports optional format conversion

Tile Shading

• Compute within a render pass
• Access to entire image block
• Access to threadgroup memory

Enhanced MSAA

• A11 GPU tracks unique sample data for even faster blending
• Imageblock Sample Coverage Control
  - Access sample coverage tracking data
  - Resolve at any time in your render pass
  - Implement custom resolve in a tile shader

Raster Order Groups

• Access memory from overlapping fragment functions in submission order
• Allows fragment functions to communicate
• A11 GPU addtions:
  - Support for Tile Shaders and Threadgroup Imageblock
  - Support for multiple Raster Order Groups

Threadgroup Sharing

• Flexible and efficient sharing of data between threads
  - Threadgroups can communicate with each other
  - Threads within a threadgroup can also communicate without a barrier
  - Use atomic operations or a memory fence

Additional Metal 2 Features

• More accurate f16 math
• Texture Cube Arrays
• Read / Write Texture
• Array of Samplers
• Post Depth Coverage
• Flexible Compute Dispatch
• Quad Scoped Permute Operations

Improved Compute Performance

• Up to 2x math performance on
  - Computer Vision
  - Image processing
  - Machine learning

Improved Performance and Capabilities