MCDMA Enables Direct RDMA Between NVIDIA Spark and Apple Silicon

StephanSturges · x · 2026-08-19

MCDMA (Metal CUDA Direct Memory Access) enables a direct RDMA path between NVIDIA Spark GPUs and Apple Silicon Macs via USB-C, allowing direct access between CUDA memory and Metal unified memory. The author's setup uses dual Sparks for prompt processing, connected concurrently to a Mac Studio for decoding via two independent USB-C links. Benchmarks show 939 MB/s on a single link, 1.80 GB/s Mac to dual Sparks, and 1.25 GB/s reverse, providing an efficient data transfer solution for heterogeneous computing architectures.

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