Chiosa
Machine Learning

DualQuant quantizes language models without calibration data

2 min ·

In plain words

DualQuant is a post-training method for making language models smaller and faster by storing both their weights and internal activations with fewer bits. It uses the model’s existing weight matrix to choose how to rescale activation channels, so it does not need sample text for calibration.

The method was tested on Qwen and Llama models in several 4-bit formats. It usually matched or beat a calibration-based method, and on one Llama test its perplexity was 6.83 versus 7.32 for SmoothQuant.

The research

Low-bit inference is useful only when both model weights and activations can be compressed, but activation outliers make that difficult.

It remains unclear whether a method can choose effective activation rescaling from the model itself, avoiding representative calibration data while preserving quality across modern low-bit formats.

DualQuant derives activation rescaling from weights and jointly optimizes format-aware row and column scales, avoiding calibration data for low-bit inference.

The researchers optimized row and column scales directly against weight-reconstruction error, with projections onto the values allowed by each 4-bit format.

They compared the resulting joint weight-and-activation representations with SmoothQuant, which uses activation samples for rescaling, and with calibration-free baselines across Qwen and Llama models.

The evidence supports the central answer: in the reported tests, calibration-free scaling can remain competitive.

For Llama-3.1-8B in NVFP4, WikiText-2 perplexity was 6.83 for DualQuant versus 7.32 for SmoothQuant, while two other calibration-free methods diverged; a fixed-weight control also showed that the column scale itself reduced activation quantization noise.

The evidence supports calibration-free joint quantization in the tested Qwen and Llama models, formats, tasks, and one packed deployment. The convergence guarantee is conditional on non-degenerate quantization and finite stabilization, and the extended SINQ+ comparisons are best-effort baselines.

Analysis

Deep