Jamba: Hybrid Transformer-Mamba Language Models
AI21-Labs · AI21 Labs · Tel Aviv University · Bar-Ilan University · Hebrew University in Jerusalem · Hebrew University of Jerusalem · AI 21 labs · Reichman University · Technion, Technion · Google DeepMind · AI21 · Tel Aviv University, Technion · University of California, San Diego · ai21 · Open University of Israel · University of Oxford · Weizmann Institute, Technion · Hebrew University of Jerusalem, Technion · Weizmann Institute of Science · AI21labs · AI21 labs · AI21Labs · School of Computer Science, Tel Aviv University · Technion - Israel Institute of Technology, Technion · IDC · Ai21 · Applied materials · Technion
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摘要
We present Jamba, a novel hybrid Transformer-Mamba mixture-of-experts (MoE) architecture. Jamba interleaves blocks of Transformer and Mamba layers, enjoying the benefits of both model families. MoE is added in some of these layers to increase model capacity while keeping active parameter usage manageable. This flexible architecture allows resource- and objective-specific configurations. We implement two configurations: Jamba-1.5-Large, with 94B active parameters, and Jamba-1.5-mini, with 12B active parameters. Built at large scale, Jamba models provide high throughput and small memory footprint compared to vanilla Transformers, especially at long-context tasks, with an effective context length of 256K tokens, the largest amongst open-weight models. At the same time, they are also competitive on standard language modeling and chatbot benchmarks. We study various architectural decisions, such as how to combine Transformer and Mamba layers, and how to mix experts, and show that some of them are crucial in large scale modeling. To support cost-effective inference, we introduce ExpertsInt8, a novel quantization technique that allows fitting Jamba-1.5-Large on a machine with 8 80GB GPUs when processing 256K-token contexts without loss of quality. We also describe several interesting properties of this architecture that the training and evaluation of Jamba have revealed. The model weights are publicly available.