The Mamba in the Llama: Distilling and Accelerating Hybrid Models
Authors: name: Junxiong Wang; name: Daniele Paliotta; name: Avner May; name: Alexander M. Rush; name: Tri Dao
Published: 2024-08-27 17:56:11

Abstract: Linear RNN architectures, like Mamba, can be competitive with Transformer
models in language modeling while having advantageous deployment
characteristics. Given the focus on training large-scale Transformer models, we
consider the challenge of converting these pretrained models for deployment. We
demonstrate that it is feasible to distill large Transformers into linear RNNs
by reusing the linear projection weights from attention layers with academic
GPU resources. The resulting hybrid model, which incorporates a quarter of the
attention layers, achieves performance comparable to the original Transformer
in chat benchmarks and outperforms open-source hybrid Mamba models trained from
scratch with trillions of tokens in both chat benchmarks and general
benchmarks. Moreover, we introduce a hardware-aware speculative decoding
algorithm that accelerates the inference speed of Mamba and hybrid models.
Overall we show how, with limited computation resources, we can remove many of
the original attention layers and generate from the resulting model more
efficiently. Our top-performing model, distilled from Llama3-8B-Instruct,
achieves a 29.61 length-controlled win rate on AlpacaEval 2 against GPT-4 and
7.35 on MT-Bench, surpassing the best instruction-tuned linear RNN model.