The code below is representative of what an actual large-model training script looks like: PyTorch's FSDP wrapper handles the parameter/gradient/optimizer sharding, activation checkpointing trades recomputation for memory, and mixed precision runs matmuls in bf16 while keeping master weights in fp32.
Layer 3 · Code
Training at Scale
A real FSDP training loop with activation checkpointing and mixed precision, plus a minimal from-scratch simulation of gradient all-reduce.
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