Cornell/IBM: looped transformers can share KV-cache across recursions, cutting memory 76-79% losslessly

WeijiaShi2 · x · 2026-10-24

Yoav Artzi's team presents 'The Surprising Effectiveness of Shared Memory in Looped Transformers' (BeNice): looped LMs add compute without more parameters, but each recursion writes its own KV-cache so memory still grows. Pretraining the model to write the cache only on the first recursion and share it (with a short window) turns out lossless — and even improves quality. At 150M-1B params, their LPT and hybrid variant set a new quality-memory frontier: with five recursions the hybrid cuts relative validation perplexity by 1.12-1.82 on FineWeb-Edu vs a same-size standard transformer while using 76-79% less context memory. Shared and local memory develop different representations; later recursions attend mostly to shared memory, which also acts as a gradient highway.

Related event: Cornell/IBM Method Lets Looped Transformers Share KV Cache, Cutting Memory by ~78%(2 posts)→

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