The Tensor Core Starvation Trap

Senior ML Engineer interview at OpenAI, and the interviewer asks:

“Your junior engineer wrote a mathematically flawless backprop loop traversing the network’s influence diagram node-by-node using explicit loops, but training takes weeks. Why must we refactor this sequential graph-traversal into Jacobian matrices for production?”

Don’t say: “Python loops are inherently slow because of the Global Interpreter Lock (GIL), so we need to rewrite the graph traversal in C++ or parallelize the node updates using multi-threading.”