Getting 50 GB/s Back Out of the ANE

Eileen Yoon identifies an RTL performance bug in the Apple M3 Neural Engine where DRAM throughput collapses from 45–60 GB/s to 17–19 GB/s whenever total weight size is an exact multiple of 1 MiB. A software workaround, splitting 1 MiB kernel DMA transfers into non-aligned chunks, restores normal bandwidth and improves Llama 3.2 1B token throughput from 10 to 24 tokens per second.

Research · Apple Silicon · Neural Engine · Performance · Hardware