Turboquant?

#141
by ghostwithahat - opened

Just out of curiosity: Why isn't anyone here using Qwen 3.8 27B with Turboquant? Has that gone out of style? It seems to work very well for me, but maybe I'm missing something important.

As far as I know, turbo quantization is missing from the llama.cpp file. Could you please tell me where I can start using it?

Are you using it with vLLM ? Which settings? Have you compared performance/accuracy vs FP8 ?

I am using buun's fork (https://github.com/spiritbuun/buun-llama-cpp).
It's the only way I can run the model with a context size of 256 K on my 3090, so i can't compare accurancy.
Working with a context size less than 256 K does not make sense to me for agentic coding.

The main reason is that it didn't actually perform as well as google claimed. Also the main innovation was the rotation matrices which was actually added to llama.cpp. It is enabled by default on all KV quants except f16 but they don't have a new name. You can read this article which compares the kv quants in more detail.

Two findings:

  • Qwen 3.8 seems to be much more stable with KV-cache-quantization than Qwen 3.6! Even with q4_0 the model works okay at big contexts.
  • With long contexts turboquant 4 still feels remarkable better than q4_0

In the website of the article mentioned above, there are a couple of other articles also showcasing kvarn kv cache and its efficiency. I use beellama with kvarn4 kv cache and am able to run UD-Q5_K_XL with 400k context (32 GB VRAM). I get great results so far, did not feel any degredation.

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