micro batching

A token still has to pass through every layer in order, so splitting the layers across nodes cannot make one token faster. The answer shows what pipelining buys instead, prices the bubble, and finds the all-reduce latency at which it beats cross-node tensor parallelism.

Inside one batch there is nothing to overlap: every layer waits for its all-to-all. Split the batch in two and one half computes while the other communicates. The answer models the gain, finds the batch size where splitting makes things slower, and checks it against a shipped default.