Can we run Q4 on llama cpp with some compact optimization config without offloading into CPU (which makes it slow) in 16 GB VRAM?

#14
by Mapraw - opened

~/Desktop/llama.cpp/build/bin/llama-server -m /home/mapraw/Desktop/llama.cpp/models/Qwen3.6-27B-Q4_0.gguf --ctx-size 0 --cache-type-k q4_0 --cache-type-v q4_0 --jinja --n-gpu-layers 999 --flash-attn on --no-mmap

I tried this and doesn't work. Or should I go back to use 35B A3B ?

Thanks !

Mapraw changed discussion title from Can we run Q4 on llama cpp with some compact optimization config without offloading into CPU (which makes it slow) ? to Can we run Q4 on llama cpp with some compact optimization config without offloading into CPU (which makes it slow) in 16 GB VRAM?

Why are you using Q4_0 is your system that old or something and wouldn't --ctx-size 0 just crash? You can offload the KV Cache to CPU which slow but still faster than leaving it on the GPU and I would suggest using IQ4_XS.

Also, Q4_0 is a outdated quantization scheme, the degradation is really severe. You should definitely use UD-Q3_K_XL instead, which is better than Q4_0 in every aspect.
You don't have enough the VRAM to fit in any Q4 quant with reasonable context length.

I recommend reducing context size to something like --ctx-size 8192. The long context degradation on Q4 KV cache is bad anyway, so you wouldn't want the full context length.

Also, Q4_0 is a outdated quantization scheme, the degradation is really severe. You should definitely use UD-Q3_K_XL instead, which is better than Q4_0 in every aspect.
You don't have enough the VRAM to fit in any Q4 quant with reasonable context length.

I recommend reducing context size to something like --ctx-size 8192. The long context degradation on Q4 KV cache is bad anyway, so you wouldn't want the full context length.

8000 is far too small of a context this thing likes to output
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