Maybe add vLLM FP8 KVCache calibration scales?

#3
by ibaldonl - opened

As the title says, this seems simple to add and should be beneficial for VRAM constrained setups.

IST Austria Distributed Algorithms and Systems Lab org

Thanks for the suggestion! In the meantime, could you try vLLM’s existing FP8 KV-cache quantization support and let us know if you observe any major degradation compared with the default KV cache?

We’re currently receiving a large number of requests for additional models and variants, so we unfortunately can’t say when we’ll be able to look into adding calibrated FP8 KV-cache scales for this checkpoint. Any results you can share would be very helpful.

@anm2211

May I ask whether you plan to release a 2-bit model with a vLLM implementation in the future? I've found ways to scale to NVFP4 KV cache, and I'd like to try fitting it onto a 12GB GPU with partly offload, KV cache calibration and reduced batch tokens.

I can't do evaluations since the GPU is shared and I have only about 2hs of maintenance window per day unfortunately :-(

IST Austria Distributed Algorithms and Systems Lab org

@ELVISIO
We actually tried 2-bit quantization but the results were below our quality standards so we decided not to release it. If you're interested in using llama.cpp, we've released smaller GGUF checkpoints that can fit on a 12 GB GPU. We definitely recommend giving those a try.

@ibaldonl
I ran some tests and didn't observe any noticeable performance degradation, so I can recommend using the FP8 KV cache. If you run into any issues with FP8 KV cache quantization, please let us know here and we'll be happy to take a look.

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