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ik_llama.cpp/github-data/pull_requests/127-Q4_0_R4 on CUDA.md
2025-07-22 18:18:40 +02:00

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🔀 #127 - Q4_0_R4 on CUDA

Author ikawrakow
State Open
Created 2024-12-08
Updated 2025-01-09

Description

With the massive improvements in prompt processing speed on the CPU achieved via interleaving 4 tensor rows (see #118, #119, #120, #121, #122, #123, #124), I was curious to see if one can get a good implementation for the X_R4 quants on CUDA. This PR is a POC that implements CUDA dequantization and matrix x vector multiplication for Q4_0_R4. It achieves the same TG speed as Q4_0. It was disappointing to not get a speedup via row interleaving, but at least there is no performance regression. To make it a full PR I should also implement quantized matrix x matrix multiplication for Q4_0_R4 (here it is done via dequantize to f16 and cuBLAS, so it is slower than Q4_0 MMQ).