What Dataflow Architectures Involve
In a weight-stationary dataflow, weights stay fixed in each processing element while activations stream through, minimizing weight-related memory traffic. In an output-stationary dataflow, partial sums stay fixed in place while weights and activations stream through, reducing the energy cost of accumulating results. Row-stationary and other hybrid approaches try to balance reuse across weights, activations, and partial sums simultaneously, rather than optimizing for just one.
Why It Matters
The best dataflow choice depends heavily on the specific characteristics of the target neural network layers – their filter sizes, channel counts, and reuse opportunities. An accelerator optimized for one dataflow pattern may perform poorly on network architectures that don't match its assumptions, making this an important early architectural decision tied closely to the intended workload.