Efficient Quantization Strategies for Latent Diffusion Models
Yuewei Yang Xiaoliang Dai Jialiang Wang Peizhao Zhang Hongbo Zhang
Latent Diffusion Models (LDMs) capture the dynamic evolution of latent
variables over time, blending patterns and multimodality in a generative
system. Despite the proficiency of LDM in various applications, such as
text-to-image generation, facilitated by robust text encoders and a variational
autoencoder, the critical need to deploy large generative models on edge
devices compels a search for more compact yet effective alternatives. Post
Training Quantization (PTQ), a method to compress the operational size of deep
learning models, encounters challenges when applied to LDM due to temporal and
structural complexities. This study proposes a quantization strategy that
efficiently quantize LDMs, leveraging Signal-to-Quantization-Noise Ratio (SQNR)
as a pivotal metric for evaluation. By treating the quantization discrepancy as
relative noise and identifying sensitive part(s) of a model, we propose an
efficient quantization approach encompassing both global and local strategies.
The global quantization process mitigates relative quantization noise by
initiating higher-precision quantization on sensitive blocks, while local
treatments address specific challenges in quantization-sensitive and
time-sensitive modules. The outcomes of our experiments reveal that the
implementation of both global and local treatments yields a highly efficient
and effective Post Training Quantization (PTQ) of LDMs.