# How Long Prompts Block Other Requests - Optimizing LLM Performance

DevFeed: [How Long Prompts Block Other Requests - Optimizing LLM Performance](<https://devfeed.tech/articles/how-long-prompts-block-other-requests-optimizing-llm-performance-7516.md>)

Original publisher: [Read original article](<https://huggingface.co/blog/tngtech/llm-performance-blocked-by-long-prompts>)

Author: Benjamin Merkel

Published: 2025-06-12T08:00:13Z

Content type: article

Language: en

Sources: [Hugging Face - Blog](<https://devfeed.tech/sources/hugging-face-blog.md>)

Topics: [vllm](<https://devfeed.tech/topics/vllm.md>), [Large Language Model](<https://devfeed.tech/topics/llm.md>), [Latency](<https://devfeed.tech/topics/latency.md>), [GPU](<https://devfeed.tech/topics/gpu.md>)

Tags: [article](<https://devfeed.tech/tags/article.md>), [batching](<https://devfeed.tech/tags/batching.md>), [blog](<https://devfeed.tech/tags/blog.md>), [blog-post](<https://devfeed.tech/tags/blog-post.md>), [gpu](<https://devfeed.tech/tags/gpu.md>), [hugging-face](<https://devfeed.tech/tags/hugging-face.md>), [latency](<https://devfeed.tech/tags/latency.md>), [vllm](<https://devfeed.tech/tags/vllm.md>)

## AI overview

The article explains how long prompts can block other requests in vLLM. Because prefill processes prompt tokens in parallel and can saturate GPU utilization, chunked-prefill normally processes chunks from different requests sequentially. A long prompt can therefore delay subsequent requests, increasing latency. The article describes an improved vLLM strategy that permits parallel prefills while limiting how many concurrently processed requests may contain very long prompts.

## Source excerpt

A Blog post by TNG Technology Consulting GmbH on Hugging Face