Question on Performance Comparison using Different Cache Bit Precision

[soumendukrg]

Testing the impact of KV cache quantization on the performance of llama2 model demonstrates decrease in tokens/sec as the cache bits is reduced. However, the reduction in cache memory is observed.

Command:
python generate.py --cache_strategy full --prompt "What is a cold compress?" --checkpoint_path ./checkpoints/meta-llama/Llama-2-7b-chat-hf/model.pth --device cuda:0 --cache_bits 4/8/16

Bits: 4

• Decode tokens per sec: 13.57
• Cache Memory used: 0.07 GB

Bits: 8

• Decode tokens per sec: 17.56
• Memory used: 0.13 GB

Bits: 16

• Decode tokens per sec: 26.09
• Memory used: 0.26 GB

Is this reduction in performance expected? Is this caused due to extra quantize-dequantize operations?