Programming Tutorials

  You provisioned an A100 instance or spun up a Serverless endpoint on Azure AI. You deployed   Llama-3.1-8B-Instruct   (or 70B), advertised with a massive 128k context window. You pass in a 15k token RAG context, and the model either crashes, returns gibberish, or completely ignores the latter half of your prompt. Logs show the model effectively truncated your input at 4,096 or 8,192 tokens. This is the most common issue currently facing engineers migrating to Llama 3.1. It is not a model defect; it is a configuration misalignment between the model’s  RoPE scaling parameters  and the  inference engine’s memory allocation strategy . This post covers the root cause of this truncation and provides production-ready fixes for vLLM and Azure AI environments. The Root Cause: RoPE Scaling vs. Default Configs To understand the fix, you must understand the failure mechanism. Llama 3.1 does not natively "see" 128k tokens in the same way earlier models saw 2k tokens. ...