François Fleuret on why matrix multiplication keeps GPUs perfectly busy

francoisfleuret · x · 2026-10-13

Former Meta researcher François Fleuret explains why matrix multiplication is ideal for AI compute: memory I/O is slow and float ops are fast, but matmul transfers only O(N²) values while performing O(N³) operations — so at some N, both memory bandwidth and floating point units are perfectly saturated. It's the core reason GPUs train models so efficiently.

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