Why LLM serving wastes GPU memory

Added: 2026-05-16

[00:00:00]Every time I use a sensor prompt, the model needs GPU memory. And as the model generates text, it also stores something called the KV cache.

[00:00:11]Think of the KV cache as the model's short-term memory while answering.

[00:00:17]The longer the conversation, the more memory it needs.

[00:00:22]The more users you have, the messier the memory becomes. Traditional serving GPU systems often waste GPU memory. They reserve the big memory blocks up front.

[00:00:33]Some blocks are half used. Some are waiting. Some are stuck behind slow requests. That means your expensive GPU is not fully busy. And in AI infrastructure, idle GPU is basically money burning in silence.

[00:00:49]vLLM was created to solve this exact problem.