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System DesignMedium· Parallelism· Infrastructure· Inference

Why does aspect ratio matter beyond model quality?

Width (dmodel) determines the feasibility of tensor parallelism because weight matrices are partitioned along the hidden dimension. Depth (nlayers) determines the number of pipeline stages and the granularity of those stages. These architectural choices interact directly with the networking topology of the training cluster, often becoming the primary bottleneck for cost and performance before model quality differences are even observed.

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