What is an attention sink, and how does StreamingLLM use it for endless generation?
Evict the oldest tokens to cap the KV cache and the model falls apart. Retain only the first few tokens and it keeps generating forever. What matters is grasping why those opening tokens behave as an attention sink.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
Evict the oldest tokens to cap the KV cache and the model falls apart. Retain only the first few tokens and it keeps generating forever. What matters is grasping why those opening tokens behave as an attention sink.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
