SoloQ Cuts Diffusion Model Memory Use
- •USC researchers introduce SoloQ, calibration-free quantization for diffusion language models
- •Tests on four models show retained accuracy under 4-bit quantization and gains over calibration-based baselines
- •NVFP4 cuts peak memory by up to 2.61X and speeds inference by up to 2.24X
Researchers at the University of Southern California introduced SoloQ, a calibration-free quantization framework for diffusion language models, in a paper published on October 5 and submitted to Hugging Face on October 12. Diffusion language models generate tokens through bidirectional diffusion, but repeated full-sequence denoising requires compute-intensive forward passes; block-diffusion models also use memory-intensive KV caches. Existing post-training quantization methods rely on calibration data, even though activation distributions change across masking states and denoising steps.
SoloQ maps weights and activations into a normalized rotated basis with a predictable marginal distribution, allowing quantization without calibration data. It combines structured K-RPBH rotation with a lightweight rescaling correction. The resulting post-rotation distributions support distribution-matched codebooks and hardware-native NVFP4. For block-diffusion models, SoloQ also applies commit-time KV-cache quantization to compress persistent states without perturbing the block being actively denoised.
The researchers tested SoloQ on full-sequence models LLaDA and Dream, and block-diffusion models Fast-dLLM v2 and Nemotron-Labs-Diffusion. Under 4-bit quantization, it retained accuracy and outperformed calibration-based baselines on knowledge- and reasoning-intensive benchmarks. With NVFP4, SoloQ reduced peak memory by up to 2.61X and accelerated end-to-end inference by up to 2.24X. The paper lists Donghyun Lee, Arkapravo Ghosh, Varun Manjunath, Bumjoon Kyle Rhee, Hyunho Kook, Shiting Xiao, Youngeun Kim and Priyadarshini Panda as authors.