@nathanrs: New post! A drawback of diffusion LLMs is that bidirectional attention causes keys and values to drift across steps, br…

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Summary

A new post highlights a drawback of diffusion LLMs: bidirectional attention causes keys and values to drift across steps, breaking KV caching. However, generation quality is robust to slight KV drift, and research has focused on maximizing stale KV reuse without quality degradation.

New post! A drawback of diffusion LLMs is that bidirectional attention causes keys and values to drift across steps, breaking KV caching. But generation quality is robust to slight KV drift, and much work has gone into maximizing stale KV reuse without causing quality drops (1/3) https://t.co/C7AAzjkUJ8
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Cached at: 06/29/26, 02:22 AM

New post! A drawback of diffusion LLMs is that bidirectional attention causes keys and values to drift across steps, breaking KV caching. But generation quality is robust to slight KV drift, and much work has gone into maximizing stale KV reuse without causing quality drops (1/3)

Most common ways to add noise to text are masking (replace clean tokens with [MASK] tokens) and uniform noise (swap with random tokens instead). Both have many different properties and it was unclear whether caching strategies for the former would work on the latter (2/3)

It turns out it does, for two reasons that are noise process agnostic: decoding prefers left-to-right (confidence is highest next to already-resolved tokens) and state transitions’ impact on KV drift is local. Thus, masking caching strategies seem to generalize to others (3/3)

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