Metal Kernel Writing Guide

This skill guides you through implementing Metal kernels for PyTorch operators on Apple Silicon.

Important: The goal of this skill is to use native Metal capabilities via the c10/metal/ infrastructure, NOT MPSGraph. Native Metal kernels provide better control, performance, and maintainability.

Overview

There are two workflows covered by this skill:

1. Adding new MPS support - Implementing a new operator from scratch
2. Migrating from MPSGraph - Converting existing MPSGraph-based operators to native Metal

Both workflows involve:

1. Update dispatch in aten/src/ATen/native/native_functions.yaml
2. Write Metal kernel in aten/src/ATen/native/mps/kernels/
3. Implement host-side stub in aten/src/ATen/native/mps/operations/

Step 1: Update native_functions.yaml